This disclosure relates generally to hydrogen aircraft fuel storage and, more particularly, to integrated cryogenic hydrogen tank systems and methods for operating the same.
In recent years, hydrogen aircraft have been developed that include multiple onboard cryogenic tanks to store liquid hydrogen fuel. As opposed to some land-based hydrogen vehicles that typical include one onboard cryogenic tank, hydrogen aircraft include multiple tanks to store more fuel while efficiently occupying space in the fuselage and to provide redundancies in the event of tank failure (e.g., pressure build-up, temperature increases above cryogenic limits, etc.).
In general, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. The figures are not to scale. Instead, the thickness of the layers or regions may be enlarged in the drawings. Although the figures show layers and regions with clean lines and boundaries, some or all of these lines and/or boundaries may be idealized. In reality, the boundaries and/or lines may be unobservable, blended, and/or irregular.
As used herein, unless otherwise stated, the term “above” describes the relationship of two parts relative to Earth. A first part is above a second part, if the second part has at least one part between Earth and the first part. Likewise, as used herein, a first part is “below” a second part when the first part is closer to the Earth than the second part. As noted above, a first part can be above or below a second part with one or more of: other parts therebetween, without other parts therebetween, with the first and second parts touching, or without the first and second parts being in direct contact with one another.
As used herein, stating that any part (e.g., a layer, film, area, region, or plate) is in any way on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, indicates that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween.
As used herein, connection references (e.g., attached, coupled, connected, and joined) may include intermediate members between the elements referenced by the connection reference and/or relative movement between those elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and/or in fixed relation to each other. As used herein, stating that any part is in “contact” with another part is defined to mean that there is no intermediate part between the two parts.
Unless specifically stated otherwise, descriptors such as “first,” “second,” “third,” etc., are used herein without imputing or otherwise indicating any meaning of priority, physical order, arrangement in a list, and/or ordering in any way, but are merely used as labels and/or arbitrary names to distinguish elements for ease of understanding the disclosed examples. In some examples, the descriptor “first” may be used to refer to an element in the detailed description, while the same element may be referred to in a claim with a different descriptor such as “second” or “third.” In such instances, it should be understood that such descriptors are used merely for identifying those elements distinctly that might, for example, otherwise share a same name.
“Including” and “comprising” (and all forms and tenses thereof) are used herein to be open ended terms. Thus, whenever a claim employs any form of “include” or “comprise” (e.g., comprises, includes, comprising, including, having, etc.) as a preamble or within a claim recitation of any kind, it is to be understood that additional elements, terms, etc., may be present without falling outside the scope of the corresponding claim or recitation. As used herein, when the phrase “at least” is used as the transition term in, for example, a preamble of a claim, it is open-ended in the same manner as the term “comprising” and “including” are open ended. The term “and/or” when used, for example, in a form such as A, B, and/or C refers to any combination or subset of A, B, C such as (1) A alone, (2) B alone, (3) C alone, (4) A with B, (5) A with C, (6) B with C, or (7) A with B and with C. As used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing structures, components, items, objects and/or things, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. As used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A and B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B. Similarly, as used herein in the context of describing the performance or execution of processes, instructions, actions, activities and/or steps, the phrase “at least one of A or B” is intended to refer to implementations including any of (1) at least one A, (2) at least one B, or (3) at least one A and at least one B.
As used herein, singular references (e.g., “a”, “an”, “first”, “second”, etc.) do not exclude a plurality. The term “a” or “an” object, as used herein, refers to one or more of that object. The terms “a” (or “an”), “one or more”, and “at least one” are used interchangeably herein. Furthermore, although individually listed, a plurality of means, elements or method actions may be implemented by, e.g., the same entity or object. Additionally, although individual features may be included in different examples or claims, these may possibly be combined, and the inclusion in different examples or claims does not imply that a combination of features is not feasible and/or advantageous.
As used herein, “approximately” and “about” modify their subjects/values to recognize the potential presence of variations that occur in real world applications. For example, “approximately” and “about” may modify dimensions that may not be exact due to manufacturing tolerances and/or other real world imperfections as will be understood by persons of ordinary skill in the art. For example, “approximately” and “about” may indicate such dimensions may be within a tolerance range of +/−10% unless otherwise specified in the below description.
As used herein, the phrase “in communication,” including variations thereof, encompasses direct communication and/or indirect communication through one or more intermediary components, and does not require direct physical (e.g., wired) communication and/or constant communication, but rather additionally includes selective communication at periodic intervals, scheduled intervals, aperiodic intervals, and/or one-time events.
As used herein, “processor circuitry” is defined to include (i) one or more special purpose electrical circuits structured to perform specific operation(s) and including one or more semiconductor-based logic devices (e.g., electrical hardware implemented by one or more transistors), and/or (ii) one or more general purpose semiconductor-based electrical circuits programmable with instructions to perform specific operations and including one or more semiconductor-based logic devices (e.g., electrical hardware implemented by one or more transistors). Examples of processor circuitry include programmable microprocessors, Field Programmable Gate Arrays (FPGAs) that may instantiate instructions, Central Processor Units (CPUs), Graphics Processor Units (GPUs), Digital Signal Processors (DSPs), XPUs, or microcontrollers and integrated circuits such as Application Specific Integrated Circuits (ASICs). For example, an XPU may be implemented by a heterogeneous computing system including multiple types of processor circuitry (e.g., one or more FPGAs, one or more CPUs, one or more GPUs, one or more DSPs, etc., and/or a combination thereof) and application programming interface(s) (API(s)) that may assign computing task(s) to whichever one(s) of the multiple types of processor circuitry is/are best suited to execute the computing task(s).
In some examples used herein, “upstream” and “downstream” refer to the location along a fluid flow path relative to the direction of fluid flow. For example, with respect to a fluid flow, “upstream” refers to a location from which the fluid flows, and “downstream” refers to a location toward which the fluid flows. For example, when a system includes a tank and a pump, and when fluid flows from the tank to the pump, then the tank is said to be upstream of the pump, and the pump is said to be downstream of the tank.
Examples and teachings disclosed herein are summarized for purposes of reading the description below. Example integrated cryogenic hydrogen tank systems (“integrated tank systems”) are disclosed herein. Multiple cryogenic tanks are connected together to enable example integrated tank systems disclosed herein to operate as a single vessel on a hydrogen aircraft. A number of (e.g., two, three, six, etc.) example cryogenic hydrogen tanks described below can be fluidly coupled in parallel and/or in series via vacuum jacketed flowlines to freely and/or controllably transmit liquid hydrogen (LH2) and hydrogen vapor (gaseous hydrogen (GH2)) across the example integrate tank systems. Thus, example integrated tank systems disclosed herein can include example LH2 refueling systems to refuel the number of cryogenic tanks substantially simultaneously via a refueling flowline connected to one of the cryogenic tanks. Furthermore, example integrated tank systems disclosed herein can include example phase separating LH2 pump systems to extract LH2 from the number of cryogenic tanks substantially simultaneously via an extraction flowline connected to one of the cryogenic tanks. In some examples, extraction flowlines of example integrated tank systems disclosed herein transmit LH2 and/or GH2 to hydrogen fuel cell power systems to electronically power various onboard systems. Example integrated cryogenic hydrogen tank systems disclosed herein can further include monitoring systems to detect the health and safety of cryogenic hydrogen tanks, flowlines, fuel supply systems, and/or fuel consumption systems associated with disclosed examples. In some examples, integrated tank systems disclosed herein include example fuel systems for detecting and diluting hydrogen leaks that may occur. The example fuel systems include compartments to contain various components of example integrated tank systems. As such, the example fuel systems can detect hydrogen leaks from the example integrated tank systems and dilute the leaks in the compartments.
Hydrogen aircraft use hydrogen fuel (diatomic hydrogen) to eliminate carbon dioxide emissions relative to commercial aircraft that combust hydrocarbon fuels (e.g., Jet-A) for propulsion. However, hydrogen fuel poses a number of challenges as compared with combustible hydrocarbon liquid fuel. For example, in its gaseous form, hydrogen fuel has a much lower power density than Jet-A fuel. Even when hydrogen fuel is stored in the liquid phase, the liquid hydrogen (LH2) fuel requires approximately four times the volume of Jet-A fuel to operate the aircraft over a given range. Moreover, hydrogen fuel has a relatively low boiling point and must be stored at cryogenic temperatures to be maintained in the liquid phase. A storage tank holding liquid hydrogen cryogenically requires more space overall and has an increased weight as compared with a storage tank holding a comparable volume of Jet-A fuel.
To extend a given flight range, hydrogen aircraft can be designed with multiple cryogenic tanks rather than a larger single cryogenic tank to store more LH2 fuel. Increasing the size and capacity of a single onboard cryogenic tank in the aircraft can restrict storage space, passenger space, weight distribution, etc. The larger cryogenic tank can also include more robust designs including stronger materials, thicker wall dimensions, and/or internal support structures. These cumulative weight increases for a single cryogenic tank can far exceed increased weight costs associated with including multiple (e.g., six) onboard cryogenic tanks to supplement aircraft range. However, there can be some challenges when multiple cryogenic hydrogen tanks are included onboard an aircraft to operate as distinct/separate tanks. For example, multiple disparate onboard LH2 tanks may have inconsistent fuel levels during flight, separate refueling lines, separate refueling processes, separate fuel extraction systems, separate monitoring systems, separate pressure safety systems, etc.
For example, when refueling multiple individual cryogenic tanks, each tank may have a separate refueling port, and a refueling line may need to be connected/disconnected to/from each port when refueling each respective tank. Furthermore, after disconnecting from a first tank and before connecting to a second tank, the refueling line is purged to remove any excess LH2 or GH2 that can warm new incoming LH2 fuel from an LH2 fuel supply tank. Similarly, separate cryogenic tanks may have individual extraction lines to transmit LH2 or GH2 fuel to hydrogen engines, fuel management systems, and/or hydrogen fuel cells. Coordinating fuel extraction from separate tanks at disparate times can result in multiple flowlines/valves and/or complex control systems to extract fuel in a manner that would not reduce fuel contents in any one tank more so than another tank, which can cause a weight imbalance on the aircraft.
Furthermore, cryogenic tanks onboard hydrogen aircraft must follow safety standards (e.g., Federal Aviation Administration (FAA), International Organization for Standardization (ISO), etc.) regarding pressure safeguards. For example, an onboard cryogenic tank can be connected to a pressure safety system, which includes a pressure safety valve and a burst disc. The pressure safety valve is included to vent GH2 when vapor pressures rise above a maximum operating pressure (e.g., a safety threshold). The burst disc is included to rupture and quickly expel GH2 in case flow through the pressure safety valve is not fast enough to adequately account for the rising vapor pressures. When using separate, discrete, and/or unconnected cryogenic tanks, individual pressure safety systems can be included and coupled to each tank. Having a separate pressure safety system for each tank can invoke excessive costs, increased weight, decreased space, and design complexities.
In examples disclosed herein, integrated cryogenic hydrogen tank systems are utilized on an example hydrogen aircraft to provide increased LH2 fuel capacity while operating as a single tank system. The example integrated cryogenic hydrogen tank systems include at least two tanks (e.g., two, four, six cryogenic LH2 tanks, etc.) connected via LH2 flowlines and hydrogen vapor flowlines. These example flowlines can communicate (e.g., transfer, transmit, share, etc.) LH2 and GH2 between tanks in the integrated tank system. Thus, when LH2 fuel is being refueled to the first tank, the fuel can propagate to the second tank as well as third, fourth, fifth, sixth tanks, etc. Similarly, when LH2 (or GH2) is extracted from one of the integrated cryogenic hydrogen tanks, the level(s) of LH2 and/or GH2 can remain consistent among the tanks in the integrated system.
In example integrated cryogenic hydrogen tank systems disclosed herein, valves are included in the communication flowlines to isolate one or more tanks from the system. For example, when a first group of tanks (e.g., a first group of three tanks) is isolated from a second group of tanks (e.g., a second group of three tanks), then LH2 fuel can be extracted from the first group and not the second group, or vice versa. When the example first group is low on fuel, LH2 can be trimmed from the second group to redistribute and balance out the integrated tank system. Furthermore, if a first tank in the first group were to fail, uncontrollably leak, depressurize during flight, etc., the first tank can be isolated from the other tanks in the first group of tanks as well as from the second group of tanks. As used herein, “trim,” “trimmed,” “trimming,” or other instances of the term refer to refueling of a first tank by supplying LH2 from one or more other tanks in the example integrated system.
In examples disclosed herein, the first group of tanks in the integrated tank system can be connected to a first pressure safety system and the second group of tanks can be connected to a second pressure safety system. Thus, if one or more of the tanks in the first group were to fail, uncontrollably leak, depressurize during flight, etc., the first group of tanks can be isolated from the second group of tanks and the first pressure safety system can relieve the rising pressures. Accordingly, the second group of tanks can be used for the remainder of the flight, and the second pressure safety system can safeguard the vapor pressures therein. In other words, the example integrated cryogenic hydrogen tank systems disclosed herein can provide redundancies to aircraft fuel storage systems and fuel management system(s).
During storage of the LH2 in the onboard LH2 tank, the hydrogen molecules undergo exothermic reactions causing temperatures to steadily increase. This temperature increase can cause the LH2 to boil, hence the term “boil-off,” which is used herein to describe the warming and evaporation process of contained LH2. In other words, despite an insulation quality of the onboard LH2 tank, the temperature of the LH2 can rise, and the LH2 can boil-off. Hydrogen vapor bubbles formed from boil-off can enter extraction flowlines with LH2 fuel and flow downstream to an LH2 pump.
When an example LH2 tank is refueled, the LH2 forms a first portion of the internal volume of the LH2 tank (e.g., 90%), and hydrogen vapor forms a second portion of the internal volume of the LH2 tank (e.g., 10%). As used herein, the “vapor pressure” refers to pressure acting on the interior walls of a tank (e.g., an onboard LH2 tank) and the surface of a liquid (e.g., LH2) within the tank. As used herein, “saturated pressure” refers to the vapor pressure when the LH2 and the hydrogen vapor are in equilibrium. That is, when the evaporation rate of the LH2 is equal to the condensation rate of the hydrogen vapor, the LH2 and the hydrogen vapor are in equilibrium and the vapor pressure is substantially similar to a saturated pressure at the given temperature. The saturated pressure is dependent on the temperature within the tank. Thus, when the temperature of the LH2 remains substantially constant, and when the LH2 settles after a given period (e.g., one hour, two hours, 12 hours, etc.), the LH2 and the hydrogen vapor are considered to be in equilibrium, and the vapor pressure is substantially similar to the saturated pressure.
The saturated pressure can be determined based on the temperature within the tank. Thus, when the onboard LH2 tank is isolated and is left to settle (e.g., without refueling or extracting hydrogen) for a given time (e.g., two hours, three hours, 12 hours, etc.) without heat addition, the temperature can remain substantially similar over time, the evaporation and condensation rates can equalize, and the vapor pressure can become substantially similar (e.g., equal) to the saturated pressure. Alternatively, when heat is added to the tank (e.g., via a thermosiphon loop, a heater, etc.), the evaporation rate of the LH2 increases and causes the vapor pressure to increase above the saturated pressure. In other words, when the temperature of the LH2 increases from a first temperature to a second temperature, the saturated pressure and the evaporation rate increase accordingly. However, the vapor pressure associated with the increased evaporation rate is greater than the saturated pressure associated with the second temperature. During operation, when the vapor pressure becomes substantially similar to the saturated pressure, there is not enough net positive pressure to drive the LH2 into extraction flowlines and cavitation can occur in the LH2. Thus, during operation, the vapor pressure is kept sufficiently higher than the saturated pressure. For example, the vapor pressure is maintained at levels that satisfy a safety threshold and an operational threshold of example integrated tank systems disclosed herein.
The first aircraft 100 illustrated in
The first aircraft 100 also includes a propulsion system that produces a propulsive thrust required to propel the first aircraft 100 in flight, during taxiing operations, and the like. The propulsion system for the first aircraft 100 shown in
The wings 120 are attached to the fuselage 110 at example attachment points 124. As the first aircraft 100 is propelled through the air, the wings 120 generate lift and the resultant lift acts on the first aircraft 100 at a wing center of lift (described below), sometimes also referred to as a center of pressure.
The engines 140 shown in
Example integrated cryogenic hydrogen tank systems disclosed herein are described as including first tank 160, second tank 170, and/or other cryogenic hydrogen tanks to provide LH2 fuel to be combusted in the hydrogen turbine engines 140. However, in some examples, integrated cryogenic hydrogen tank systems disclosed herein can be used to supply LH2 and/or GH2 to other power systems, such as hydrogen fuel cells, power generators, and/or other electrical generators that rely on hydrogen fuel to function.
Example integrated cryogenic hydrogen tank systems disclosed herein are configured to hold the hydrogen fuel at least partially within the liquid phase and are configured to provide hydrogen fuel to the fuel delivery assembly 150 substantially completely in the liquid phase. However, due to refueling processes, in-flight sloshing, boil-off, etc., the LH2 can include vapor bubbles which can flow into LH2 extraction flowlines. Such vapor bubbles can cause cavitation damage to LH2 pumps driving flow from example integrated tank systems. Thus, example phase separating LH2 pump systems are included in example integrated tank system disclosed herein. Such phase separating LH2 pump systems are described in greater detail below.
As used herein, the term “substantially completely” is used to describe a liquid phase of the hydrogen fuel and refers to a unit mass (e.g., one kilogram (kg), one pound (lb.), etc.) of LH2 that includes near 100% hydrogen in the liquid phase, such as at least 99%, such as at least 97.5%, such as at least 95%, such as at least 92.5%, such as at least 90%, such as at least 85%, or such as at least 75% of LH2 per unit mass. For example, one unit mass of LH2 substantially completely in the liquid phase can include 95% liquid hydrogen and 5% hydrogen vapor bubbles.
To store the hydrogen fuel substantially completely in the liquid phase, the hydrogen fuel is stored in example integrated tank systems at cryogenic temperatures. For example, the first and second tanks 160, 170 can store hydrogen fuel at a temperature of −253 degrees Celsius (° C.) (20 Kelvin (K)) and a saturated pressure of 15 pounds per square inch (psi) to maintain the hydrogen fuel substantially completely in the liquid phase. In some examples, example integrated tank systems can store hydrogen fuel at temperatures from −259° C. (14 K) to −243° C. (30 K) and saturated pressures from 0 psi to 122 psi, and in some other examples, at temperatures from −253° C. (20 K) to −243° C. (30 K) and saturated pressures from 15 psi to 122 psi. As noted above, storing hydrogen fuel in the liquid phase within a volume sufficient to power the first aircraft 100 over a range of a typical continental flight, international flight, overseas flight, etc., can require larger cryogenic hydrogen tank(s) (e.g., first tank 160, second tank 170, etc.). However, in examples disclosed herein, integrated cryogenic hydrogen tank systems can include two or more tanks (e.g., with equal or lesser volume) to increase the range of the example first aircraft 100.
The first tank 160 and the second tank 170 are positioned within the fuselage 110 such that the moment arms MFT, MAT are balanced when fuel levels therein are substantially similar. When the first and second tanks 160, 170 are separated and not included in example integrated tank systems disclosed herein, the fuel delivery assemblies 150 are to extract LH2 from the first and second tanks 160, 170 substantially simultaneously so as not to significantly unbalance the aircraft 100. Such synchronization can lead to complex control systems of the fuel delivery assemblies 150. Furthermore, when separated, the first and second tanks 160, 170 cannot trim and/or redistribute fuel if fuel extraction becomes unsynchronized. Thus, the first and second tanks 160, 170 can be included in example integrated tank systems disclosed herein to refuel and/or extract LH2 to/from the first and second tanks 160, 170 substantially simultaneously without complex and/or multiple control systems for the fuel delivery assemblies 150.
The second aircraft 300 illustrated in
In some examples, the second aircraft 300 includes a fuel delivery system to provide LH2 fuel from example integrated tank systems to the first and second groups of engines 308a, 308b. The first and second groups of engines 308a, 308b can combust the fuel to generate a propulsive thrust and propel the second aircraft 300 in flight, during taxiing operations, and the like. In the example of
Similar to the example first aircraft 100 of
Example integrated cryogenic hydrogen tank systems disclosed herein can store LH2 fuel in a first group of cryogenic hydrogen tanks 324 (“first group of tanks 324”) and a second group of cryogenic hydrogen tanks 326 (“second group of tanks 326”). The first group of tanks 324 includes a first tank 324a, a second tank 324b, and a third tank 324c. The second group of tanks 326 includes a fourth tank 326a, a fifth tank 326b, and a sixth tank 326c. In some examples, the tanks 324a-324c, 326a-326c are substantially similar to the first and second tanks 160, 170 described in connection with
In the illustrated example of
In some examples, the first and second groups of tanks 324, 326 are located in the fuselage 312 such that, relative to the forward and aft directions, the first, third, fourth, and sixth centers of gravity 328a, 328c, 330a, 330c are substantially equidistant from the wing center of lift 321. Similarly, relative to the port and starboard directions, the first, third, fourth, and sixth centers of gravity 328a, 328c, 330a, 330c are substantially equidistant from the centerline 310. An example forward tank moment arm, MFT, extends from the wing center of lift 321 to the centers of gravity of the two forward tanks, and an example aft tank moment arm, MAT, extends from the wing center of lift 321 to the centers of gravity of the two aft tanks. When the first and second groups of tanks 324, 326 are of substantially similar sizes/geometries, are filled/trimmed to substantially similar LH2 capacities, and are included in example integrated tank systems, the moments generated by the front and aft centers of gravity, the MFT, and the MAT are substantially equal. As shown in
The second aircraft 300 illustrated in
Some disadvantages and/or challenges arise in hydrogen aircraft (e.g., the first and/or second hydrogen aircraft 100 (
Another example disadvantage and/or challenge includes a fuel extraction system and/or process associated with the multiple individual tanks. For example, each of the multiple individual tanks include separate outlet valves connected to separate extraction flowlines and/or separate fuel delivery systems leading to a same destination (e.g., main fuel lines, engines, hydrogen fuel cells, etc.). Including extraction flowlines, valves, LH2 pumps, etc. for each individual tank incurs excessive weight and/or financial costs for the first and/or second aircraft 100 (
Another example disadvantage and/or challenge associated with multiple individual/separate tanks onboard hydrogen aircraft (e.g., the first and/or second hydrogen aircraft 100 (
Example integrated cryogenic hydrogen tank systems and methods for operating the same are disclosed herein. Example integrated tank systems enable hydrogen aircraft (e.g., the first and/or second aircraft 100 (
The example tank 400 illustrated in
The example tank 400 includes an inner vessel 406, an outer vessel 408, and an insulation layer 410 between the inner and outer vessels 406, 408. The combined use of the inner and outer vessels 406, 408 and the insulation layer 410 enables the tank 400 to maintain internal cryogenic temperatures and to keep hydrogen in the liquid phase without significant and/or excessive warming, boil-off, and/or saturated pressure increases. In some examples, the insulation layer 410 is multi-layer insulation (MLI), which includes multiple (e.g., 5, 10, 30, etc.) layers of thin sheets (e.g., polyimide and/or polyester) and is typically used in vacuum environments (e.g., in space) due to the proficiency of MLI to reduce heat transfer due to radiation. Thus, the insulation layer 410, otherwise referred to as a vacuum layer, is depressurized to near-zero pressures (e.g., 1.322*10−11 Pascal (Pa)) to maintain the substantially cryogenic temperature of the LH2 fuel.
Additionally, as used herein, the term “vacuum jacketed flowline” refers to a flowline with an MLI medium between an inner flowline and an outer flowline, wherein the MLI medium is depressurized to a near-zero pressure. Example vacuum jacketed flowlines referred to herein can be rigid and/or flexible flowlines and can be connected to tanks, valves, ports, and/or other flowlines via a bayonet connection. An example bayonet connection includes a male bayonet and female port that are precisely manufactured with a low tolerance (e.g., 0.001, 0.005 inches, etc.) to provide a slip fit. Bayonet connections can also include O-ring(s) and clamp(s) to inhibit leakage and insulative materials to inhibit heat loss at the connection.
The example tank 400 illustrated in
The example tank 400 illustrated in
In the illustrated example, the LH2 extraction flowline 422 is fluidly coupled to the lower portion 402 of the internal chamber 101. In some examples, the LH2 extraction flowline 422 is also fluidly coupled to a cryogenic LH2 pump to transmit LH2 to example power generators, such as a fuel cell power system, a gas turbine engine, and/or the like. In some examples, the tank 400, the LH2 extraction flowline 422, and the cryogenic LH2 pump are implemented in an example phase separating LH2 pumping system as described in connection with
The example second GH2 extraction flowline 426 is included in the tank 400 to discharge hydrogen vapor (GH2) to a power supply system. For example, the second GH2 extraction flowline 426 can lead to a pump and/or compressor that direct(s) GH2 to a hydrogen fuel cell power system where energy released from chemical bonding between hydrogen vapor and oxygen (e.g., extracted from the air) is captured and converted to electrical energy. Example hydrogen fuel cell power systems that can be powered via example integrated tank systems disclosed herein are described in detail below with reference to
The example third GH2 extraction flowline 428 is included in the tank 400 to release GH2 via the pressure relief valve 430 when the vapor pressure does not satisfy (e.g., exceeds) a safety threshold. In some examples, the safety threshold is a vapor pressure value, such as 150 psi, 175 psi, 200 psi, etc. In some examples, the safety threshold corresponds to some amount of pressure (e.g., 10 psi, 20 psi, 25 psi, etc.) below a catastrophic limit of the tank 400 and/or example integrated tank systems disclosed herein. In some examples, the catastrophic limit corresponds to a saturated pressure (e.g., 200 psi, 225 psi, 250 psi, etc.) or a range of saturated pressures (e.g., between 175 psi and 225 psi, etc.) at which significant damage can occur to the tank 400 and/or example integrated tank systems disclosed herein. Thus, in some examples, the safety threshold corresponds to a vapor pressure or a range of vapor pressures (e.g., between 160 psi and 180 psi) below the catastrophic limit.
The pressure relief valve 430 can be of a spring-loaded and/or diaphragm configuration that is designed to automatically open in response to the saturated pressure not satisfying the safety threshold and/or exceeding a maximum allowable working pressure (MAWP) of the tank 400. In other words, when the temperature of the LH2 increases, the evaporation rate and the vapor pressure also increases, and, thus, the quantity of GH2 in the upper portion 404 increases due to boil-off. In some examples, the tank 400 includes pressure sensor(s) in the upper portion 404 to measure and/or determine the vapor pressure of the internal chamber 401. When the vapor pressure exceeds the safety threshold (e.g., the MAWP), the pressure relief valve 430 opens/actuates and releases a portion of the GH2 from the upper portion 404. In some examples, as described below, the tank 400 and/or a group of tanks is/are connected to a pressure safety system that also releases GH2 when the vapor pressure does not satisfy the safety threshold. In such examples, the pressure relief valve 430 is included in the tank 400 and/or the group of tanks to open and release GH2 when the vapor pressure does not satisfy another safety threshold (e.g., a second safety threshold) that is less than the safety threshold (e.g., the MAWP) as described above. Thus, in such examples, the pressure relief valve 430 can be included in example integrated tank systems disclosed herein as a safety redundancy. In some examples, the third GH2 extraction flowline 428 leads to another tank for receiving and storing the discharged hydrogen vapor. Additionally or alternatively, the second GH2 flowline 426 and/or the third GH2 extraction flowline 428 can lead to frangible panels on the first aircraft 100 and/or the second aircraft 300 to discharge hydrogen vapor to surrounding atmosphere. Such frangible panels (or quick release panels) are described in greater detail below with reference to
Although not always shown, in some examples, integrated cryogenic hydrogen tank systems illustrated in
The example first and second tanks 400a, 400b are connected by an example LH2 transfer flowline 502 and an example GH2 transfer flowline 504. The example LH2 and GH2 transfer flowlines 502, 504 are vacuum jacketed flowlines as mentioned previously and as indicated in
The example first integrated system 500 illustrated in
The first integrated system 500 includes the GH2 transfer flowline 504 to allow GH2 to freely flow between the first and second tanks 400a, 400b. For example, when LH2 in the lower portion 402 of the first tank 400a generates hydrogen vapor due to boil-off, the hydrogen vapor can enter the upper portion 404 of the second tank 400b, and vice versa. Since quantities of LH2 and GH2 can be consistent between the first and second tanks 400a, 400b, the vapor pressure, saturated pressure, and temperature can likewise be consistent across the first integrated system 500. That is, when thermodynamic properties (e.g., saturated pressure, temperature, etc.) of the first tank 400a change, the corresponding thermodynamic properties of the second tank 400b adjust substantially simultaneously and by a same or similar amount.
The example pressure safety system 602 releases hydrogen vapor from the second integrated system 600 to outside atmosphere when the vapor pressure does not satisfy (e.g., exceeds) the safety threshold. In some examples, the second integrated system 600 (or another integrated system disclosed herein) includes the pressure relief valve 430 of
When the vapor pressure in the first and/or second tank 400a, 400b do(es) not satisfy (e.g., exceed(s)) the safety threshold, the pressure safety system 602 can take effect. In some examples, the first and second pressure safety valves 606a, 606b are designed to fully open automatically (e.g., via a deadweight, collapsible gate, etc.) in response to pressure(s) at or above the safety threshold. In some examples, unlike the pressure relief valve 430, the first and second pressure safety valves 606a, 606b open in an irreversible manner such that the first and second pressure safety valves 606a, 606b cannot close when upstream pressure reduces and/or satisfies the safety threshold.
The example pressure safety system 602 illustrated in
As mentioned previously, the example pressure safety system 602 includes the example first and second pressure safety valves 606a, 606b to automatically actuate to a fully open state to release hydrogen vapor when the vapor pressure does not satisfy the safety threshold. The first and second pressure safety valves 606a, 606b differ from the example pressure relief valve 430 (
In some examples, the first and/or second pressure safety valves 606a, 606b do not open quickly enough and/or a mechanism of the valve(s) may fail to operate as intended. The example pressure safety system 602 includes the example first and second burst discs 608a, 608b as safeguards against such example cases. The example first and second burst discs 608a, 608b include a one-time-use membrane made of one or more layers of metal and/or other materials. The example membrane is designed to rupture at a given pressure differential and can rupture near instantaneously (e.g., within one millisecond) when the vapor pressure no longer satisfies the safety threshold. In some examples, the first and second burst discs 608a, 608b are designed to another safety threshold (e.g., a third safety threshold) which is a value (e.g., 1 psi, 3 psi, 5 psi, etc.) greater than the safety threshold (or the example second safety threshold mentioned previously) to provide the first and/or second pressure safety valves 606a, 606b with some time to open prior to the burst discs rupturing.
As mentioned previously, in some examples, the second GH2 extraction flowline 426, the third GH2 extraction flowline 428, and the pressure relief valve 430 as described with regard to
The example third integrated system 700 illustrated in
The example thermosiphon loop 702 includes the heat exchanger 706 to convert the LH2 to hydrogen vapor by introducing heat to the LH2. The example heat exchanger 706 uses a fluid heat source (e.g., water, oil, supercritical carbon dioxide, etc.) that can transfer heat to the LH2 and cause the LH2 to boil-off at a designated rate. The heat exchanger 706 can control the temperature and pressure of the output hydrogen vapor based on the temperature of the fluid heat source, the amount of LH2 exposed to the heat source in the heat exchanger 706, the amount of LH2 that the automatic valve 708 discharges, the flowrate of the LH2 in the heat exchanger 706, etc. The example heat exchanger 706 can output hydrogen vapor at a pressure that is greater than a current vapor pressure within the third integrated system 700 such that GH2 flows back into the upper portion 404 of the third integrated system 700 until the vapor pressure satisfies (e.g., is greater than or equal to) the operational threshold. As illustrated in
The example third integrated system 700 includes the heating system 704 to complement the thermosiphon loop 702 and accelerate the increase of the saturated pressure. The heating system 704 is also included as a redundancy in case the thermosiphon loop 702 or one or more components therein fail(s) to function as intended. For example, the thermosiphon loop 702 may not produce hydrogen vapor at a high enough vapor pressure to drive the GH2 back into the third integrated system 700. In another example, the automatic valve 708 may fail to open causing the thermosiphon loop 702 to produce any hydrogen vapor. Thus, the example heating system 704 can supplement or replace the thermosiphon loop 702. The example heating system 704 includes the example heater 710 to increase the temperature of the LH2 and cause the rate of boil-off (evaporation rate) to increase. As the rate of boil-off increases, more hydrogen vapor is created, which accordingly increases the vapor pressure within the third integrated system 700. In some examples, one or more other heaters 710 are included in the second and/or third tanks 400b, 400c. The example heating system 704 includes the battery cell 712 to provide electrical power to the heater 710 for operation.
The example fourth integrated system 800 illustrated in
In an example use case of the fourth integrated system 800, all isolation valves 802 are initially open to synchronize conditions across the fourth integrated system 800, and the vapor pressure in the third tank 400c rapidly rises to a level that no longer satisfies the safety threshold. Even though conditions (e.g., temperature and pressure) in the second and first tanks 400b, 400a eventually increase, the conditions in the third tank 400c increase to the safety threshold first, indicating that the third tank 400c is the origin of the high-pressure event. Therefore, the controlling device 804 causes the isolation valves 802 between the second tank 400b and the third tank 400c to close. The pressure safety system 602 can release the pressure in the third tank 400c such that significant damage(s) do(es) not occur. Thus, the third tank 400c is depressurized, the isolation valves 802 between the second and third tanks 400b, 400c are closed, and GH2 from the first and second tanks 400a, 400b can flow into the third tank 400c via the GH2 extraction flowlines 424. Therefore, the vapor pressure can still be consistent across the fourth integrated system 800. Furthermore, LH2 extraction flowlines 422 are included in each of the first, second, and third tanks 400a, 400b, 400c to allow LH2 fuel to still be extracted from the fourth integrated system 800 when one or more of the isolation valves 802 are closed.
The example fourth integrated system 800 illustrated in
The controlling device 804 includes the example pressure controller circuitry 806 to detect vapor pressure(s) within the fourth integrated system 800, determine whether the vapor pressure(s) satisfy the operational threshold, and/or to cause the thermosiphon loop 702 and/or the heating system 704 to increase the vapor pressure in the fourth integrated system 800 when the vapor pressure(s) do not satisfy the operational threshold. In some examples, the pressure controller circuitry 806 is instantiated by processor circuitry executing pressure controller instructions and/or configured to perform operations such as those represented by the flowchart of
In yet some other examples, the operational threshold corresponds to a difference between the vapor pressure and the saturated pressure, such as 1 psi, 5 psi, 10 psi, 25 psi, etc. In such examples, the fourth integrated system 800 can include one or more temperature sensors in the tanks 400a-c, and the pressure controller circuitry 806 can determine the saturated pressure based on the measured temperature of the LH2 in the fourth integrated system 800. In such examples, the pressure controller circuitry 806 can determine whether the difference between the vapor pressure and the saturated pressure satisfies the operational threshold and, when the difference does not satisfy the operational threshold, cause the thermosiphon loop 702 and/or the heating system 704 to increase the vapor pressure until the operational threshold is satisfied.
The example pressure controller circuitry 806 can determine whether the vapor pressure satisfies the operational threshold. For example, the operational threshold of the fourth integrated system 800 can be a vapor pressure of 50 psi. In such an example, the pressure controller circuitry 806 determines that the vapor pressure is 45 psi based on pressure measurements via one or more pressure sensor(s). Since the current vapor pressure does not satisfy the operational threshold, the pressure controller circuitry 806 causes the automatic valve 708 of the thermosiphon loop 702 to open and/or causes the heater 710 of the heating system 704 to activate, in turn, causing the vapor pressure to increase until the operational threshold is satisfied.
The controlling device 804 includes the example isolation controller circuitry 808 to detect vapor pressure(s) within the fourth integrated system 800, determine whether the vapor pressure(s) satisfy the safety threshold, cause one or more isolation valves 802 to open such that LH2 and/or GH2 is evenly extracted from the fourth integrated system 800, and/or cause one or more isolation valves 802 to close when the vapor pressure(s) do not satisfy the safety threshold. In some examples, the isolation controller circuitry 808 is instantiated by processor circuitry executing isolation controller instructions and/or configured to perform operations such as those represented by the flowchart of
The example isolation controller circuitry 808 can determine whether the vapor pressure satisfies the safety threshold. For example, the safety threshold for the fourth integrated system 800 can be a vapor pressure of 160 psi. In such an example, the isolation controller circuitry 808 determines that the vapor pressure is 162 psi based on pressure measurements via one or more pressure sensor(s). Since the current vapor pressure does not satisfy the safety threshold, the isolation controller circuitry 808 causes the isolation valves 802 between the second tank 400b and the third tank 400c to close. In some examples, the isolation controller circuitry 808 can also detect whether the first burst disc 608a and/or the second burst disc 608b has/have ruptured. In response to detecting that one of the first or second burst discs 608a, 608a has ruptured, the isolation controller circuitry 808 can switch the direction of the switch valve 604 to an intact valve/burst disc side.
The controlling device 804 includes the example storage device(s) 810 to store machine readable instructions and measurement and/or position data obtained from the example pressure sensors and/or valves mentioned above. The example storage device(s) 810 can be volatile memory device(s), non-volatile memory device(s), and/or mass storage device(s). The example controlling device 804 includes the example interface circuitry 812 to communicate with example pressure sensors, temperature sensors, valves, etc. described above. In some examples, the interface circuitry 812 facilitates communication between programmable circuitry (e.g., processor circuitry such as the pressure controller circuitry 806, the isolation controller circuitry 808, etc.) and the storage device(s) 810. In some examples, the interface circuitry 812 enables the controlling device 804 to receive command inputs from an external source. The interface circuitry 812 is able to receive and/or transmit commands via wired and/or wireless connections.
The fifth integrated system of
As illustrated in
In some examples, the third set of isolation valves 802c between the first and second groups of tanks 902, 904 can be initially closed and remain closed during flight until the controlling device 804 (e.g., the isolation controller circuitry 808) detects or generates a command to open the third set of isolation valves 802c. In some examples, the LH2 is extracted from the first group of tanks 902 (e.g., via one or more LH2 extraction flowlines 422) prior to extracting LH2 from the second group of tanks 904. In some examples, an operator (e.g., a pilot, co-pilot, engineer, etc.) of an example aircraft can cause the third set of isolation valves 802c to open such that LH2 is trimmed from the second group of tanks 904 to the first group of tanks 902 until the quantity of LH2 in the tanks is consistent across the fifth integrated system 900.
Additionally or alternatively, the fifth integrated system 900 includes the first and second groups of tanks 902, 904 to provide added redundancy to the fifth integrated system 900 in response to tank failure(s). In some examples, when the third set of isolation valves 802c are open, the example isolation controller circuitry 808 can cause the third set of isolation valves 802c to close in response to the vapor pressure not satisfying the safety threshold. Thus, for example, when one or more of the tanks of the second group of tanks 904 fails and/or is significantly damaged, the first group of tanks 902 can operate as intended without losing a significant amount of LH2, becoming depressurized, and/or warming to a substantially high temperature.
The example fifth integrated system 900 includes the example cryogenic pumps 906 to trim LH2 from one tank to another tank and/or from one group of tanks to another group of tanks. For example, when LH2 is extracted from the first group of tanks 902, and the operator trims the LH2 fuel from the second group of tanks 904 to the first group of tanks 902, the operator can also activate one or more of the cryogenic pumps 906 in the second group of tanks 904 to accelerate the trimming process. In some examples, one cryogenic pump 906 is included in respective ones of the first group of tanks 902 and the second group of tanks 904.
It should be appreciated that components and/or elements of the example integrated cryogenic hydrogen tank systems 500-900 can be altered, rearranged, and/or modified in a configuration not illustrated in
A flowchart representative of example machine readable instructions, which may be executed to configure processor circuitry to implement the controlling device 804 of
The machine readable instructions described herein may be stored in one or more of a compressed format, an encrypted format, a fragmented format, a compiled format, an executable format, a packaged format, etc. Machine readable instructions as described herein may be stored as data or a data structure (e.g., as portions of instructions, code, representations of code, etc.) that may be utilized to create, manufacture, and/or produce machine executable instructions. For example, the machine readable instructions may be fragmented and stored on one or more storage devices and/or computing devices (e.g., servers) located at the same or different locations of a network or collection of networks (e.g., in the cloud, in edge devices, etc.). The machine readable instructions may require one or more of installation, modification, adaptation, updating, combining, supplementing, configuring, decryption, decompression, unpacking, distribution, reassignment, compilation, etc., in order to make them directly readable, interpretable, and/or executable by a computing device and/or another machine. For example, the machine readable instructions may be stored in multiple parts, which are individually compressed, encrypted, and/or stored on separate computing devices, wherein the parts when decrypted, decompressed, and/or combined form a set of machine executable instructions that implement one or more operations that may together form a program such as that described herein.
In another example, the machine readable instructions may be stored in a state in which they may be read by processor circuitry, but require addition of a library (e.g., a dynamic link library (DLL)), a software development kit (SDK), an application programming interface (API), etc., in order to execute the machine readable instructions on a particular computing device or other device. In another example, the machine readable instructions may need to be configured (e.g., settings stored, data input, network addresses recorded, etc.) before the machine readable instructions and/or the corresponding program(s) can be executed in whole or in part. Thus, machine readable media, as used herein, may include machine readable instructions and/or program(s) regardless of the particular format or state of the machine readable instructions and/or program(s) when stored or otherwise at rest or in transit.
The machine readable instructions described herein can be represented by any past, present, or future instruction language, scripting language, programming language, etc. For example, the machine readable instructions may be represented using any of the following languages: C, C++, Java, C#, Perl, Python, JavaScript, HyperText Markup Language (HTML), Structured Query Language (SQL), Swift, etc.
As mentioned above, the example operations of
At block 1104, the example controlling device 804 detects the vapor pressure(s) in one or more of the example integrated cryogenic hydrogen tank system(s) 500-900. For example, the pressure controller circuitry 806 and the isolation controller circuitry 808 obtain pressure measurements from pressure sensor(s) in each of the tanks (e.g., one or more of tanks 400a-f) of the integrated cryogenic hydrogen tank system(s) 500-900. In some other examples, the pressure and isolation controller circuitry 806, 808 obtain pressure measurements of the first and second groups of tanks 902, 904. In general, the controlling device 804 can determine which of the isolation valves 802 are closed and can obtain vapor pressure measurements from each of the isolated portions of the one or more integrated tanks systems 500-900.
Blocks 1106 and 1110 can occur concurrently, substantially simultaneously, synchronously, and/or asynchronously in the example operations 1100. At block 1106, the controlling device 804 determines whether the vapor pressure(s) in the integrated cryogenic hydrogen tank system(s) 500-900 satisfy the safety threshold. For example, the isolation controller circuitry 808 can determine whether the vapor pressure(s) in the first, second, third, fourth, fifth, and/or sixth tanks 400a-f is/are less than the safety threshold. The example isolation controller circuitry 808 repeats block 1106 until such determinations are made for portions (e.g., the first, second, third, fourth, fifth, and/or sixth tanks 400a-f, the first group of tanks 902, the second group of tanks 904, etc.) of the integrated cryogenic hydrogen tank system(s) 500-900. When the isolation controller circuitry 808 determines that the vapor pressure(s) do(es) satisfy the second safety threshold, then the example operations 1100 proceed to block 1114.
When the isolation controller circuitry 808 determines that the vapor pressure(s) do not satisfy the second safety threshold (e.g., the vapor pressure is greater than or equal to the safety threshold), the example operations 1100 proceed to block 1108. At block 1108, the controlling device 804 closes the isolation valves 802 connected to the at-risk tank(s) and/or group(s) of tanks. For example, when the vapor pressure of the first tank 400a in
At block 1110, the controlling device 804 determines whether the vapor pressure(s) in the integrated cryogenic hydrogen tank system(s) 500-900 satisfy the operational threshold. For example, the pressure controller circuitry 806 can determine whether the vapor pressure(s) in the first, second, third, fourth, fifth, and/or sixth tanks 400a-f is/are greater than or equal to the operational threshold. The example pressure controller circuitry 806 repeats block 1110 until such determinations are made for portions (e.g., the first, second, third, fourth, fifth, and/or sixth tanks 400a-f, the first group of tanks 902, the second group of tanks 904, etc.) of the integrated cryogenic hydrogen tank system(s) 500-900. When the pressure controller circuitry 806 determines that the vapor pressures do satisfy the operational threshold, then the example operations 1100 proceed to block 1114.
When the pressure controller circuitry 806 determines that the vapor pressure(s) do not satisfy the operational threshold (e.g., the saturated pressure is less than the operational threshold), the example operations 1100 proceed to block 1112. At block 1112, the controlling device 804 causes the automatic valve 708 of the thermosiphon loop 702 to open and/or causes the heater 710 of the heating system 704 to activate. For example, when vapor pressure in the first tank 400a of
At block 1114, the controlling device 804 determines whether an input to stop extracting the LH2 and/or GH2 has been detected, obtained, received, commanded, etc. When the controlling device 804 determines that an example system (e.g., example LH2 pumping systems described below) is to continue extracting LH2 and/or GH2 fuel from the example integrated cryogenic hydrogen tank system(s) 500-900, then the example operations 1100 return to block 1104. When the controlling device 804 determines that the example system is to stop extracting LH2 and/or GH2 fuel from the example integrated cryogenic hydrogen tank system(s) 500-900, then the example operations 1100 end. Additionally or alternatively, when extraction of the LH2 and/or GH2 is to cease, the isolation controller circuitry 808 can cause one or more of the isolation valves 802 to close.
The processor platform 1200 of the illustrated example includes processor circuitry 1212. The processor circuitry 1212 of the illustrated example is hardware. For example, the processor circuitry 1212 can be implemented by one or more integrated circuits, logic circuits, FPGAs, microprocessors, CPUs, GPUs, DSPs, and/or microcontrollers from any desired family or manufacturer. The processor circuitry 1212 may be implemented by one or more semiconductor based (e.g., silicon based) devices. In this example, the processor circuitry 1212 implements the pressure controller circuitry 806 and the isolation controller circuitry 808.
The processor circuitry 1212 of the illustrated example includes a local memory 1213 (e.g., a cache, registers, etc.). The processor circuitry 1212 of the illustrated example is in communication with a main memory including a volatile memory 1214 and a non-volatile memory 1216 by a bus 1218. The volatile memory 1214 may be implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS® Dynamic Random Access Memory (RDRAM®), and/or any other type of RAM device. The non-volatile memory 1216 may be implemented by flash memory and/or any other desired type of memory device. Access to the main memory 1214, 1216 of the illustrated example is controlled by a memory controller 1217.
The processor platform 1200 of the illustrated example also includes interface circuitry 1220. The interface circuitry 1220 may be implemented by hardware in accordance with any type of interface standard, such as an Ethernet interface, a universal serial bus (USB) interface, a Bluetooth® interface, a near field communication (NFC) interface, a Peripheral Component Interconnect (PCI) interface, and/or a Peripheral Component Interconnect Express (PCIe) interface.
In the illustrated example, one or more input devices 1222 are connected to the interface circuitry 1220. The input device(s) 1222 permit(s) a user to enter data and/or commands into the processor circuitry 1212. The input device(s) 1222 can be implemented by, for example, a keyboard, a button, a mouse, a touchscreen, a trackpad, a trackball, an isopoint device, and/or a voice recognition system.
One or more output devices 1224 are also connected to the interface circuitry 1220 of the illustrated example. The output device(s) 1224 can be implemented, for example, by display devices (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display (LCD), a cathode ray tube (CRT) display, an in-place switching (IPS) display, a touchscreen, etc.), a printer, and/or speaker. The interface circuitry 1220 of the illustrated example, thus, typically includes a graphics driver card, a graphics driver chip, and/or graphics processor circuitry such as a GPU.
The interface circuitry 1220 of the illustrated example also includes a communication device such as a transmitter, a receiver, a transceiver, a modem, a residential gateway, a wireless access point, and/or a network interface to facilitate exchange of data with external machines (e.g., computing devices of any kind) by a network 1226. The communication can be by, for example, an Ethernet connection, a digital subscriber line (DSL) connection, a telephone line connection, a coaxial cable system, a satellite system, a line-of-site wireless system, a cellular telephone system, an optical connection, etc.
The processor platform 1200 of the illustrated example also includes one or more mass storage devices 1228 to store software and/or data. Examples of such mass storage devices 1228 include magnetic storage devices, optical storage devices, floppy disk drives, HDDs, CDs, Blu-ray disk drives, redundant array of independent disks (RAID) systems, solid state storage devices such as flash memory devices and/or SSDs, and DVD drives.
The machine readable instructions 1232, which may be implemented by the machine readable instructions of
From the foregoing, it will be appreciated that example systems, methods, apparatus, and articles of manufacture have been disclosed to integrate multiple cryogenic hydrogen tanks onboard an aircraft and enable the integrated tank system to operate as a single vessel. Disclosed systems, methods, apparatus, and articles of manufacture improve: (i) the efficiency of a hydrogen-powered aircraft via pressure and temperature control of LH2 fuel onboard the aircraft, (ii) the stability and control of a hydrogen-powered aircraft via even storage distribution of LH2 onboard the aircraft, (iii) the range of the aircraft via increased available LH2 storage onboard the aircraft, (iv) the refueling/extraction processes of the multi-tank hydrogen aircraft via interconnections of the multiple cryogenic hydrogen tanks, and so forth. As such, disclosed systems, methods, apparatus, and articles of manufacture can accordingly be directed to one or more improvement(s) in the operation of a machine such as a hydrogen powered aircraft or another hydrogen-powered vehicle.
Example integrated cryogenic hydrogen tank systems described above can be further improved based on types and/or configurations of tanks used therein. Decreasing the size of the tanks used in the integrated systems can provide more space for cargo bays, passenger seating, artillery storage, etc. Decreasing the weight of the tanks used in the integrated systems can extend the range, the empty weight, the power-to-weight ratio, etc. of the aircraft. Described below are example cryogenic tanks/tank systems for liquid hydrogen that can be used in example integrated tank systems described above.
The cryogenic tanks/tank systems can store liquid hydrogen (diatomic hydrogen) onboard an aircraft for use as a fuel to power the aircraft or components thereof. In some examples, the fuel tank discussed below is a lightweight tank made from dual wall composite cylinders. Despite a vacuum layer of insulation, an amount of heat can transfer to the LH2 from surrounding ambient air, resulting in boil-off. The LH2 fuel is preferably extracted from the fuel tank without GH2 bubbles caused by boil-off. As LH2 is extracted from the fuel tank, the volume of LH2 therein decreases and the volume of GH2 therein increases, which increases the possibility of entrainment of hydrogen vapor bubbles in the extracted LH2. Examples of hydrogen fuel tanks discussed below are configured to reduce or to eliminate the presence of such hydrogen vapor (GH2) entrained in the LH2 provided to the fuel system of the aircraft. Example fuel tanks discussed below account for disturbances (e.g., sloshing, swirling, etc.) of the LH2 due to movements of the aircraft during flight (e.g., pitches, rolls, rotations, etc.).
Referring now to
The tank 1300 stores hydrogen fuel at substantially low (cryogenic) temperatures to keep the LH2 substantially completely in the liquid phase. For example, the tank 1300 can store LH2 at about −253° C. (20 K) or less at atmospheric pressure, or at other temperatures and corresponding saturated pressures shown in the chart 1000 of
The tank 1300 can function as a cryostat to store and maintain the hydrogen fuel in the liquid phase. The tank 1300 is a dual wall tank and includes an inner vessel 1310 (inner cryogenic liquid tank) and an outer vessel 1320 (vacuum vessel).
As shown in
The outer vessel wall 1322 also is a multi-layer wall, having an inner layer 1324 and an outer layer 1326. Based on similar considerations as discussed above for the inner vessel wall 1312, the inner layer 1324 of the outer vessel wall 1322 can be constructed of metal, such as aluminum or steel, and the outer layer 1326 of the outer vessel wall 1322 can be constructed of a composite material, such as carbon fiber. Each of the inner layer 1324 and the outer layer 1326 can include similar thicknesses as discussed above.
As noted above, the inner vessel 1310 is positioned within the outer vessel 1320 with the gap 1330 formed between the inner vessel 1310 and the outer vessel 1320 and, more specifically, between the inner vessel wall 1312 and the outer vessel wall 1322. To provide thermal isolation for the inner vessel 1310, the gap 1330 has a vacuum pressure, such as from zero to one millitorr. In some examples, the gap 1330 includes void space. Additionally or alternatively, the gap 1330 includes multi-layer insulation (MLI) in the gap 1330. Suitable MLIs included in the gap 1330, such as aluminized Mylar®, are known to persons having ordinary skill in the art.
As shown in
The tank 1300 is refueled via at least one liquid hydrogen fill line 1363, 1365. In some examples, the tank 1300 includes a lower liquid hydrogen fill line 1363 and an upper liquid hydrogen fill line 1365. The lower liquid hydrogen fill line 1363 and the upper liquid hydrogen fill line 1365 can extend from the chamber 1350 to a coupling located on the exterior of an aircraft, such as on the exterior of the fuselage 110, the fuselage 312, etc. In some examples, a valve is incorporated into the coupling or positioned between the coupling and the chamber 1350. Example sub-cooling LH2 refuelers described below with reference to
A fuel extraction line 1367 is included to fluidly couple the chamber 1350 to example LH2 pump(s) (e.g., example phase separating LH2 pump systems described below with reference to
As shown in
In some examples, the angle α of the fuel extraction line 1367 is at least the maximum pitch of the aircraft 100, such as at least twenty degrees. In some other examples, the angle α is set to be at least five degrees greater than the maximum pitch of the aircraft 100, such as at least twenty-five degrees. For example, the fuel extraction line 1367 angles downward at an angle α of twenty-five degrees relative to the longitudinal axis 1306 and the centerline 106. In such an example, the centerline 106 of the aircraft 100 is substantially parallel to the horizontal plane 10. At the beginning of a mission (flight), the aircraft 100 is on the ground and at idle, as illustrated in
In some examples, the fuel extraction line 1367 is located on the forward end of the tank 1300 and extends in the forward direction of the aircraft 100. To the extent that the liquid hydrogen flows away from the fuel extraction line 1367 when the pitch of the aircraft 100 is upward, such as during takeoff and climb, the volume of liquid hydrogen in the tank 1300 is near full and the upward pitch of the aircraft 100 does not prevent the supply of fuel to the fuel extraction line 1367. As the flight progresses, the volume of the liquid hydrogen fuel in the tank 1300 decreases and may be near empty at the end of the flight. As the aircraft 100 descends, the liquid hydrogen fuel remaining in the tank 1300 flows toward the forward end of the tank 1300. With the fuel extraction line 1367 located on the forward end of the tank 1300 and extending in the forward direction of the aircraft 100, the liquid hydrogen fuel flows toward the fuel extraction line 1367 and continues to supply the fuel extraction line 1367. When the tank 1300 is included in example integrated tank systems described above, LH2 can be trimmed to the tank 1300 from another tank when the LH2 levels are below the horizontal plane 10 of
The example cryogenic tank(s) 1300 described above with reference to
Example integrated cryogenic hydrogen tank systems described above include multiple interconnected tanks that can be refueled substantially simultaneously, similar to a single vessel. Sub-cooling refuelers described below can control temperatures and pressures of the flowing LH2 fuel during refueling processes of hydrogen aircraft. The integrated tank systems can store LH2 more efficiently when refueled with sub-coolers because the LH2 can be introduced to the integrated tank system at desired cryogenic conditions to increase the density of the LH2, and thus, the storage capacity of the integrated tank system.
The operations of some refueling systems for onboard cryogenic fuel tanks refuel cryogenic fuels at temperatures similar to the temperatures at which the cryogenic fuels are stored prior to refueling. In some examples, a cryogenic fuel is stored in a supply tank at a temperature corresponding to a saturated pressure that is above atmospheric pressure. In such examples, the cryogenic fuel is stored at saturated pressures above atmospheric pressure in the onboard cryogenic fuel tanks. In some examples, a supply tank is driven to a take-off and/or a launch site to refuel the onboard tank with cryogenic fuel (e.g., liquid hydrogen (LH2)). In such examples, the LH2 is stored in an insulated supply tank but the temperature of the LH2 is still unregulated, in which case the mass of the onboard LH2 is neither controllable nor functionally optimized.
In examples described below, a sub-cooler in refueling system for a hydrogen aircraft reduces the temperature and increases the density of LH2 during refueling such that smaller onboard cryogenic fuel tank(s) (e.g., tanks 400, tanks 1300, etc.) can be used to store the same mass of LH2, and the mass of LH2 supplied to the onboard cryogenic fuel tank(s) can be precisely controlled. For example, when LH2 is provided by a supply tank at 25 Kelvin (K), the density of the LH2 fuel is about 64 kg/m3 onboard an example hydrogen aircraft. The example sub-cooler described below can reduce the temperature of the LH2 to 20 K while refueling, thus increasing the density of LH2 to about 71 kg/m3 and reducing the onboard tank volume by about 10%.
The example illustration of
The flow control valve 1904 operates at working temperatures lower than 233 K and can be used for transmitting low temperature cryogenic fluid (e.g., liquefied natural gas, liquid oxygen, liquid hydrogen, etc.). In some examples, the flow control valve 1904 regulates the flow of the cryogenic fluid such that a known mass of fuel can be provided to an integrated tank system 1912. The example flow control valve 1904 is constructed to thermally insulate the cryogenic fuel during transmission so that the fluid does not heat up, vaporize, and leak out as a gas. In some examples, the flow control valve 1904 is connected to the supply tank 1902 by one or more VJ flowlines 1910. The integrated tank system 1912 of
The example cryogenic refueling system 1900 can further include a manually operated or electronically actuated cryogenic valve 1908. In some examples, the cryogenic valve is a shut-off valve to quickly terminate flow to the integrated tank system 1912 such that the integrated tank system 1912 does not overfill. The example cryogenic valve 1908 is constructed to thermally insulate the cryogenic fuel during transmission so that the fluid does not heat up, vaporize, and leak out as a gas. In some examples, the cryogenic valve 1908 is connected to the integrated tank system 1912 by one or more VJ flowlines 1910.
In some examples, the VJ flowlines 1910 illustrated in
The example cryogenic refueling system 1900 illustrated in
As shown in
The example sub-cooler 2004 illustrated in
The example sub-cooler 2004 illustrated in
The example sub-cooler 2004 illustrated in
The example sub-cooler 2004 illustrated in
The example sub-cooler 2004 illustrated in
The example position loop controller 2036 determines an actual first valve actuator position based on the commanded first valve actuator position. The example position loop controller 2036 generates a primary first valve effective area and an auxiliary first valve effective area based on the actual first valve actuator position. In some examples, the primary first valve effective area is at the inlet of the primary flowline 2028. In some examples, the auxiliary first valve effective area is at the inlet of the auxiliary flowline 2030. By increasing the primary first valve effective area in conjunction with decreasing the auxiliary first valve effective area, the temperature of the cryogenic fuel in the primary flowline 2028 (measured by the temperature sensor 2012) increases. By decreasing the primary first valve effective area in conjunction with increasing the auxiliary first valve effective area, the temperature of the cryogenic fuel in the primary flowline 2028 (measured by the temperature sensor 2012) decreases.
The example cryogenic heat exchanger 2010 of the sub-cooler 2004 illustrated in
The example sub-cooling cryogenic refueling system 2000 illustrated in
The example sub-cooling cryogenic refueling system 2000 illustrated in
The example vaporizer 2022 illustrated in
The example supply tank 2002 of
The example pressure building coil 2016 of
The example transfer pump 2018 of
At block 2102, the supply tank 2002 increases vapor pressure within the supply tank 2002 and/or increases the vapor pressure within the system 2000. The supply tank 2002 has a pressure building coil 2016 as illustrated in
At block 2104, the cryogenic valve 1908 is opened either manually or electronically by the sub-cooler controller 2032 or another controller integrated into the system 2000. Opening the cryogenic valve 1908 begins the refueling of the integrated tank system 2014, allowing the cryogenic fuel to pass through the sub-cooler 2004 into the integrated tank system 2014.
At block 2106, the cryogenic fuel is sub-cooled by the sub-cooler 2004. For example, the cryogenic fuel from the supply tank 2002 flows to a first valve 2006 that splits the flow into a primary flowline 2028 and an auxiliary flowline 2030. The auxiliary flowline 2030 directs the cryogenic fuel to a second valve 2008 that lowers the saturated pressure and temperature of the cryogenic fuel. Both the primary flowline 2028 and the auxiliary flowline 2030 flow to a cryogenic heat exchanger 2010, where heat is transferred from the primary flowline 2028 to the auxiliary flowline 2030. The sub-cooled cryogenic fuel in the primary flowline 2028 is then directed to a temperature sensor 2012 and ultimately to an integrated tank system 2014.
At block 2108, the temperature of the cryogenic fuel is measured by the temperature sensor 2012 and stored at multiple intervals over the duration of the refueling operation. The measured temperatures can be stored in the sub-cooler controller memory 2040 and/or in some other memory located in the system 2000.
At block 2110, the density of the cryogenic fuel is determined and stored at the same intervals over the duration of the refueling operation based on example thermodynamic properties as illustrated in
At block 2112, the volumetric flowrate is measured by the flowmeter 1906 and stored at the same intervals over the duration of the refueling operation. The measured flowrates can be stored in the sub-cooler controller memory 2040 and/or in another memory located in the system 2000.
At block 2114, the sub-cooler controller 2032 and/or another computing device located in the system 2000 can determine the total mass of cryogenic fuel stored in the integrated tank system 2014 based on the temperatures, densities, and flowrates measured and/or determined over the duration of the refueling operation. For example, the sub-cooler 2004 can refuel LH2 to the integrated tank system 2014 at 20 K, which corresponds to an LH2 density of 71 kg/m3. In such an example, the integrated tank system 2014 can have a maximum volume capacity for LH2 of 18 m3. If the flowmeter measures the volumetric flowrate to be 0.01 m3/s, while the example LH2 is 20 K, then the time it takes to refuel the integrated tank system 2014 is 30 minutes and the total mass of refueled LH2 is 1278 kg.
At block 2116, the sub-cooler controller 2032 or another controlling device located in the system 2000 can determine if the total mass of cryogenic fuel stored in the integrated tank system 2014 is at the target total mass (e.g., 1278 kg). If the total mass of the cryogenic fuel in the integrated tank system 2014 is not at the target capacity, then the sub-cooling cryogenic refueling operation continues as control reverts to block 2106.
At block 2118, if the total mass of the cryogenic fuel in the integrated tank system 2014 is at the target capacity, then the sub-cooler controller 2032 or another controlling device located in the system 2000 can send an electronic signal to the cryogenic valve 1908 to shut off the flow and end the refueling operation. Alternatively, if the total mass of the cryogenic fuel in the integrated tank system 2014 is at the target capacity, then the cryogenic valve can be shut off manually.
At block 2202, the first valve 2006 of the sub-cooler 2004 separates the flow of cryogenic fuel from the supply tank 2002 into a primary flowline 2028 and an auxiliary flowline 2030. For example, the controller can actuate the first valve 2006 such that the primary first valve effective area is 90% of the maximum area of the inlet to the primary flowline 2028 and the auxiliary first valve effective area is 10% of the maximum area of the inlet to the auxiliary flowline 2030. Therefore, 90% of the cryogenic fuel from the supply tank 2002 flows into the primary flowline 2028 and 10% of the cryogenic fuel from the supply tank 2002 flows into the auxiliary flowline 2030.
At block 2204, the second valve 2008 of the sub-cooler 2004 reduces the saturated pressure of the cryogenic fuel in the auxiliary flowline 2030, thereby reducing the temperature of the cryogenic fuel in the auxiliary flowline 2030. For example, the second valve 2008 can expand LH2 in the auxiliary flowline 2030 such that the LH2 temperature drops from 24 K to 16 K and the LH2 saturated pressure drops from 40 psi to 14 psi.
At block 2206, the sub-cooler 2004 directs the primary flowline 2028 and the auxiliary flowline 2030 to the cryogenic heat exchanger 2010. At block 2208, the cryogenic heat exchanger 2010 processes the cryogenic fuel from the primary flowline 2028 and the auxiliary flowline 2030 to transfer heat from the primary flowline 2028 to the auxiliary flowline 2030, which sub-cools the cryogenic fuel flowing through the primary flowline 2028. For example, the cryogenic fuel temperature entering the cryogenic heat exchanger 2010 via the primary flowline 2028 can be 24 K and the cryogenic fuel temperature entering the cryogenic heat exchanger 2010 via the auxiliary flowline 2030 can be 16 K. In such an example, the cryogenic fuel temperature exiting the cryogenic heat exchanger 2010 via the primary flowline 2028 can be 20 K, depending on how much cryogenic fuel was diverted to the auxiliary flowline 2030 by the first valve 2006.
At block 2210, the sub-cooler 2004 directs the primary flowline 2028 to the temperature sensor 2012 and then, to the integrated tank system 2014. The sub-cooler 2004 also directs the auxiliary flowline to the vaporizer 2022.
Similar to the example operations of
At block 2302, the temperature loop controller 2034 determines a commanded first valve actuator position based on the temperature of the cryogenic fuel in the supply tank 2002 and the target temperature of the cryogenic fuel to be stored in the integrated tank system 2014. For example, the cryogenic fuel temperature stored in the supply tank 2002 can be 24 K and the target cryogenic fuel temperature to be stored in the integrated tank system 2014 can be 20 K. The example temperature loop controller 2034 can determine that to achieve the target temperature, the first valve actuator position shall be actuated to a position in which the primary first valve effective area is 80% of the maximum area of the inlet to the primary flowline 2028 and the auxiliary first valve effective area is 20% of the maximum area of the inlet to the auxiliary flowline 2030.
At block 2304, the position loop controller 2036 determines an actual first valve actuator position based on the commanded first valve actuator position. The commanded first valve actuator position is the position to which the spool(s) inside the first valve 2006 are to be actuated by a servomotor to achieve a desired primary and auxiliary first valve effective areas. The position loop controller 2036 obtains the actual first valve actuator position from a servomotor sensor in the first valve 2006. The position loop controller 2036 determines the error/difference between the actual first valve actuator position from the servomotor sensor and the commanded first valve actuator position from the temperature loop controller 2034. The position loop controller 2036 uses a feedback loop to control the servomotor in the first valve 2006 and reduce the error between the actual and commanded first valve actuator positions to near zero.
At block 2306, the position loop controller 2036 generates a primary first valve effective area and an auxiliary first valve effective area based on the actual first valve actuator position. The primary first valve effective area and the auxiliary first valve effective area affect the volumetric flowrates in the primary flowline 2028 and the auxiliary flowline 2030, respectively.
At block 2308, the temperature loop controller 2034 determines an error between the measured temperature from the temperature sensor 2012 and the target temperature.
At block 2310, the temperature loop controller 2034 determines if the error is within an acceptable range and/or sufficiently near zero.
At block 2312, if the temperature loop controller 2034 determines that the error is not within the acceptable range, then the temperature loop controller 2034 determines an adjusted commanded first valve actuator position based on the error and the preceding commanded first valve actuator position.
At block 2314, if the temperature loop controller 2034 determines that the error is within the acceptable range, then the position loop controller 2036 maintains the current actual first valve actuator position.
The example sub-cooling refueling systems 2000 described above with reference to
Example integrated cryogenic hydrogen tank system(s) 500-900 described above can be further improved based on types and/or configurations of LH2 pumps used to extract LH2 fuel therefrom. Example phase separating LH2 pump systems are described below that enable separation of GH2 from LH2 fuel extracted from the integrated tank system(s) 500-900. Example phase separating LH2 pump systems can return the separated GH2 back to the integrated tank system(s) 500-900 to increase the vapor pressure therein. Thus, example phase separating LH2 pump systems can reduce the use of or remove the need for vapor pressure regulation systems (e.g., the thermosiphon loop(s) 702, the heating system(s) 704, etc.) in the integrated tank system(s) 500-900. Furthermore, example phase separating LH2 pump systems described below can prevent and/or inhibit reduction of LH2 mass flowrates from the integrated tank systems 500-900 by reducing and/or elimination cavitation in an LH2 pump. Furthermore, hydrogen vapor separated from the LH2 fuel can be diverted to other hydrogen power systems (e.g., hydrogen fuel cells, engines, etc.) onboard the aircraft to reduce the use of or remove the need for GH2 flowlines, valves, compressors, and/or pumps connected to and/or leading from the integrated tank system(s). Thus, example phase separating LH2 pump systems described below can be included in the integrated tank system(s) 500-900 to improve the weight costs, performance, and/or efficiency of the integrated tank system(s) 500-900 disclosed herein.
Cryogenic pumping systems (e.g., liquid hydrogen (LH2) pumping systems, liquid nitrogen (LN2) pumping systems, etc.) are included in vehicles (e.g., aircraft, cars, trucks, ships, etc.), such as hydrogen powered vehicles, to transfer cryogenic fuel to component(s) (e.g., high-pressure receiver tanks) and/or other system(s) (e.g., hydrogen fuel cells, fuel management system(s), hydrogen engines, etc.). Such cryogenic pumping systems are described with reference to LH2 pumping systems, but it should be appreciated that such cryogenic pumping systems can apply to other types of cryogenic liquid such as LN2, liquid helium, etc. Such LH2 pumping systems include an onboard LH2 tank, a first flowline to transmit LH2 from the LH2 tank to the LH2 pump, and a second flowline to transmit hydrogen vapor from the LH2 pump back to the onboard LH2 tank. The LH2 pump includes a suction adapter, a motor, a belt-driven crank drive, and a cold end compression chamber (e.g., cylinder) with a reciprocating piston. The suction adapter enables the LH2 to flow into the compression chamber when the piston moves from a top-dead center (TDC) position to a bottom-dead center (BDC) position. The motor and the crank drive move the piston back to the TDC position to compress the LH2. The compressed LH2 (e.g., cryo-compressed hydrogen) is fed through a pump discharge flowline that leads to the component(s) and/or other system(s) of the hydrogen powered vehicle. The suction adapter can also remove some hydrogen vapor present in the first flowline and send the vapor back to the LH2 tank via the second flowline. However, in many cases, the suction adapter alone is not able to remove a sufficient quantity of hydrogen vapor from the LH2.
Hydrogen vapor bubbles, or “cavities”, can form in the onboard LH2 tank for many reasons. For example, during a refueling process of the onboard LH2 tank or any cryogenic hydrogen tank, turbulence, currents, or high flowrates can cause hydrogen vapor bubbles form in the LH2. Standard cryogenic practices stipulate that the cryogenic tank should rest for a duration (e.g., 24 hours) after the tank is refueled to allow the LH2 to settle and the vapor bubbles to dissipate. However, for hydrogen powered aircraft, there is a limited time (e.g., 30 minutes) that the aircraft is permitted to idle at an airport gate. When the hydrogen powered aircraft is refueled with LH2, there will inevitably be hydrogen vapor bubbles present within the onboard LH2 tank prior to takeoff.
In another example, during flight, the hydrogen powered aircraft can ascend or descend at non-zero angles (e.g., +/−10 degrees) relative to cruising angle (e.g., zero degrees). Additionally, the hydrogen powered aircraft can experience turbulent conditions that can cause unexpected and unstable movement of the aircraft. As the aircraft ascends, descends, and/or experiences turbulence, the LH2 fuel can migrate (e.g., slosh) in the onboard LH2 tank and new hydrogen vapor bubbles can form.
In yet another example, during storage of the LH2 in the onboard LH2 tank, the hydrogen molecules undergo exothermic reactions causing temperatures to steadily increase. This temperature increase can cause the LH2 to boil and cause a decrease in stored LH2 mass due to evaporation (boil-off). In other words, despite an insulation quality of the onboard LH2 tank, the temperature of the LH2 can rise, and the LH2 can boil-off. Hydrogen vapor bubbles formed from boil-off can enter the first flowline with the LH2 and flow downstream to the LH2 pump.
As used herein, the “suction head” refers the to the difference between the vapor pressure and the actual (static) pressure of the LH2. During the pumping process of the LH2, a net positive suction head (NPSH) is achieved when the vapor pressure is greater than the static pressure of the LH2. Furthermore, to maintain the NPSH, the vapor pressure is regulated to a value greater than the saturated pressure at the given temperature of the LH2. In some cases, the quantity of hydrogen vapor can be increased in the LH2 tank (e.g., via a thermosiphon loop, a submerged heater, a vapor return line from the suction adaptor of the LH2 pump, etc.) to increase the vapor pressure above the saturated pressure and maintain the NPSH. The NPSH is utilized during the pumping process to cause the LH2 to flow from the upstream end (e.g., the onboard LH2 tank) to the downstream end (e.g., the LH2 pump and the discharge line). In other words, a sufficiently high NPSH (e.g., 10 pounds per square inch (psi)) is created in the system to cause the LH2 to flow into the LH2 pump and allow the LH2 pump to operate properly. When the static pressure falls below the vapor pressure (e.g., when the NPSH is formed), cavitation can occur, and hydrogen vapor bubbles can form in the LH2. As used herein, “cavitation” refers to the formation of bubbles (e.g., “cavities”) in a liquid (e.g., LH2) due to movement (e.g., surface vibrations, sloshing, pouring, flowing, etc.,), boil-off, and/or the NPSH.
Since cavitation can occur in the onboard LH2 tank, the first flowline transfers both LH2 and hydrogen vapor-filled cavities from the onboard LH2 tank to the suction adapter. The suction adapter of the LH2 pump includes a conical metal grid filter that can rupture some of the bubbles and release hydrogen vapor into the second flowline to be returned to the onboard LH2 tank. However, due to the mass flow of the LH2 and the size of the filter, the suction adapter cannot eliminate all of the cavities, and some bubbles can enter into the cold end compression chamber along with the LH2.
When hydrogen vapor-filled cavities are present in the compression chamber, the piston compresses the bubbles, which causes the bubbles to collapse and generate shock waves that can damage the compression chamber, the piston, the suction adapter, the pump discharge flowline, etc. The damage caused by the collapse of the vapor cavities is referred to herein as “cavitation damage.” The shock waves formed are generally strong near the point of collapse and weaken as they propagate outward. The bubbles near the walls of the compression chamber, the piston, and/or the suction adapter can cause the most catastrophic cavitation damage. Cavitation damage can cause high stresses, pitting, and/or erosion of wetted parts and can significantly damage the LH2 pump to the point where parts included therein may be replaced sooner than anticipated. Since components of LH2 pumps are associated with high costs (e.g., tens of thousands of United States dollars), frequent repair and replacement of damaged parts or systems is inefficient, expensive, and desirable to avoid. Furthermore, cavitation can cause a significant reduction in mass flowrate of LH2 through the LH2 pump. In some cases, cavitation can be detected by a sudden increase in a discharge temperature of the compressed mixture, a sudden drop in mass flow rate, a sudden drop in pump motor oscillations, and/or a sudden decrease in vibrations of the LH2 pump.
In examples described below, phase separating LH2 pump systems can be used to remove hydrogen vapor cavities from LH2 before the LH2 reaches the suction adapter of the LH2 pump. Example phase separation systems described below include a phase separator integrated directly into the first and second flowlines mentioned above. The example phase separator is a vacuum jacketed apparatus with a sintered metal portion through which the LH2 flows. The sintered metal portion can be a porous structure constructed from additive manufacturing; wherein multiple layers of metal alloy(s) are fused together. Such metal alloy(s) are compatible with LH2 at cryogenic temperatures (e.g., metal alloys tested at 297 Kelvin (K)). As such, the sintered metal portion of the phase separator is capable of withstanding cryogenic temperatures without becoming embrittled. When LH2 flows through the phase separator, the porous channels cause the LH2 and the hydrogen vapor to separate while also reducing the temperature and saturated pressure of the LH2. As the saturated temperature decreases, the density of the LH2 increases, and the density of the hydrogen vapor decreases. Due to a phenomenon referred to herein as “buoyancy-driven flow,” density reduction of the hydrogen vapor causes the GH2 to rise out of the phase separator, into the second flowline (the hydrogen vapor return flowline), and back into the onboard LH2 tank. The density increase of the LH2 causes the LH2 to continue flowing through the sintered metal portion, into the first flowline (the LH2 flowline), and, eventually, into the LH2 pump.
Downstream of the phase separator, the first flowline includes LH2 and a substantially small amount of hydrogen vapor bubbles. In examples described below, a “substantially small” amount of hydrogen vapor bubbles corresponds to a range of quantities from zero bubbles to a quantity of bubbles (e.g., 2%, 5%, 10%, etc. of vapor per unit volume of LH2) that the suction adapter is capable of removing (e.g., via the metal grid filter) and transmitting back to the LH2 tank. In examples described below, phase separation systems for removing hydrogen gas bubbles from LH2 prior to the LH2 entering the LH2 pump results in less cavitation damage to the LH2 pump and a longer lifespan of the LH2 pump and/or components included therein, relative to current LH2 pump systems.
Example phase separating LH2 pump systems described below improve the ability to separate hydrogen vapor from the LH2/GH2 mixture extracted from the onboard LH2 tank. Thus, more hydrogen vapor can be separated from the LH2 extraction flowline and returned to the onboard LH2 tank via the vapor return flowline to increase the vapor pressure in the onboard LH2 tank. Therefore, example phase separating LH2 pump systems described below improve the ability/efficiency of LH2 pumps to extract LH2 from the onboard LH2 tanks because of the increased vapor pressure (in the onboard LH2 tanks) which maintains an increased NPSH in the system. Furthermore, increasing the vapor pressure in the onboard LH2 tank also increases the boiling point (e.g., temperature at which boil-off occurs) of the LH2. Thus, example phase separating LH2 pump systems described below reduce the amount of boil-off in the onboard LH2 tank, which reduces mass loss of LH2 fuel due to evaporation and reduces cavitation in the LH2. In some examples, the vapor return flowline can completely or partially divert the hydrogen vapor to other systems (e.g., hydrogen fuel cells, hydrogen engine fuel injectors, etc.) onboard the vehicle either at the given vapor pressure or after increasing the vapor pressure (e.g., via a compressor). For example, vapor return flowlines can direct at least a portion of the separated hydrogen vapor to a compressor, which can pressurize the vapor prior to combustion in gas turbine engine(s) (e.g., hydrogen powered engine(s)). In another example, the vapor return flowlines can direct at least a portion of the separated hydrogen vapor to a hydrogen fuel cell to convert chemical energy to electrical energy and power other onboard systems (e.g., auxiliary power, cabin air conditioning, etc.). Thus, example phase separating LH2 pump systems described below increase the amount of hydrogen fuel (e.g., GH2) available to other systems onboard the vehicle (e.g., aircraft).
For the figures described below, identical numerals indicate the same elements throughout the figures. The example illustration of
The example system 2500 illustrated in
The example onboard LH2 tank 2502 is not exclusively full of LH2, but rather includes two different states of hydrogen (e.g., LH2 and GH2) with an associated saturated pressure. The saturated pressure in the onboard LH2 tank 2502 is dependent on the temperature of the LH2 and GH2. Thus, when internal temperatures gradually increase, the saturated pressure of the onboard LH2 tank 2502 proportionally increases. Similarly, as boil-off occurs and/or when hydrogen vapor returns to the onboard LH2 tank 2502 via the GH2 flowline 2508, the vapor pressure in the onboard LH2 tank 2502 increases. In some examples, the onboard LH2 tank 2502 includes one or more pressure sensors to monitor the vapor pressure and transmit vapor pressure values to an example control system described in further detail below. In some examples, the vapor pressure is allowed to reach a value that satisfies a safety threshold while also providing a NPSH to the system 2500. As illustrated in
The example system 2500 illustrated in
In some examples, the LH2 flowline 2506, the GH2 flowline 2508, the discharge flowline 2516, and/or other flowlines are vacuum jacketed (VJ) flowlines that are rigid, flexible, or a combination thereof. The example VJ flowlines (e.g., the first, second, and/or discharge flowlines 2506, 2508, and/or 2516) are designed with an inner line, an outer line, and an intermediary layer. The example intermediary layer can include multiple alternating layers of a heat barrier and a non-conductive spacer to form gap between the inner line and the outer line. The example intermediary layer can be depressurized using a vacuum pump to create a static vacuum shield. The example vacuum shield can safeguard the cryogenic fuel from heat transfer caused by radiation, conduction, and/or convection. Thus, the LH2 flowline 2506, the second flowline 108, the discharge flowline 2516, and/or the other flowlines transport LH2 and/or GH2 throughout the example system 2500 and/or other systems described below while maintaining cryogenic temperatures and, in some examples, preventing or inhibiting boil-off. In some examples, the LH2 flowline 2506, the second flowline 2508, the discharge flowline 2516 include VJ valves, vapor vents, vapor vent heaters, VJ manifolds, etc., to further control the temperatures of the LH2 fuel.
The example system 2500 illustrated in
The example system 2500 illustrated in
The outer shell 2608 and the inner shell 2610 can be fabricated from stainless steel sheet metal pressed and/or stamped into cylindrical shapes as illustrated in
Although the phase separator 2600 can separate some GH2 present in an LH2/GH2 mixture, some limitations are imposed by the current design. For example, the separation material 2604 is constructed of steel wool that includes multiple small channels through which the LH2 can travel, thus reducing the saturation pressure of the LH2 and reducing the density of the hydrogen vapor to some degree. However, the separation material 2604 is loosely packed in the phase separator 2600 such that the structure/design/topology/consistency of the channels is random and not optimized. Furthermore, the insulation material 2612 occupies the volume between the outer and inner shells 2608, 2610 to reduce heat transfer but cannot provide the same heat transfer protection as a vacuum-insulating layer. If examples of insulation materials 2612 given above were introduced to a vacuum pressure environment, the insulation materials 2612 would likely damage and/or collapse due to insufficient internal structuring thereby lose some insulative properties. Furthermore, the outer and inner shells 2608, 2610 are made of sheet metal and lack any intermediate structures (e.g., trusses, suspensions, beams, rods, etc.) or additional materials (e.g., composites) that may enable the outer and inner shells 2608, 2610 to withstand pressure differentials between a possible vacuum insulation layer and the internal pressure or a vacuum insulation layer and the atmosphere. Since no vacuum layer is present, the phase separator 2600 cannot be integrated into vacuum jacketed flowlines of an LH2 pumping system without introducing significant heat transfer to the system. Lastly, based on the configuration, the phase separator 2600 vents the separated GH2 into atmosphere instead of capturing the vapor with a vapor return flowline. Thus, the phase separator 2600 wastes separated hydrogen vapor rather than utilizing the hydrogen vapor to increase the vapor pressure in an LH2 supply tank (e.g., onboard LH2 tank), maintain the NPSH in the pump system, fuel other onboard systems (e.g., hydrogen fuel cells, hydrogen powered engines, etc.).
The example system 2700 illustrated in
The example system 2700 illustrated in
In some examples, the filtration structure 2714 is composed of one or more metals with a sufficient tolerance against hydrogen embrittlement. Hydrogen embrittlement is a process that decreases the fracture toughness or ductility of a metal due to the presence of atomic and/or gaseous hydrogen. To test the tolerance of metal against hydrogen embrittlement, metal degradation due to hydrogen environmental embrittlement (HEE) is measured. The HEE occurs when controlled stresses are applied to the metal while being exposed to a gaseous hydrogen environment at cryogenic temperatures (e.g., 297 K) and high pressures (e.g., 100 psi). A standardized HEE index is determined for the metal based on the level of degradation experienced as a result of the HEE testing. Metallic material(s) (e.g., pure metal, metal alloy, etc.) chosen for the filtration structure 2714 are chosen based on the HEE index and embrittlement testing at room temperature. In other words, the materials of the filtration structure 2714 do not show embrittlement at cryogenic temperatures or at room temperatures. Some example metals with a sufficient HEE index for use in the filtration structure 2714 include but are not limited to austenitic steel alloys (e.g., A286, 216, 316, 22-13-5 (Nitronic 50), etc.), aluminum-based alloys (e.g., 1100-T0, 2011, 2024, 5086, 6061-T6, 6063, 7039, 7075-T73, etc.), copper alloys (e.g., copper, aluminum bronze, GRCop-84 (Cu-3Ag-0.5Zr), NARloy-Z, 70-30 brass, etc.), and/or pure titanium.
Due to the porous material that composes the filtration structure 2714, the flowrate of the two-phase (LH2 and GH2) mixture reduces and branches into multiple flow pathways in the filtration structure 2714. The flowrate reduction and flow splitting results in a decrease of temperature and saturated pressure in the two-phase mixture. When the temperature and saturated pressure of the two-phase mixture decreases, the density of the LH2 phase decreases and the density of the GH2 phase increases (shown in
The example system 2800 illustrated in
The example system 2800 illustrated in
The example system 2800 illustrated in
The example system 2800 illustrated in
The example controlling device 2814 illustrated in
The threshold may be a predetermined value written into the pressure loop instructions. In some examples, there are multiple thresholds for the different possible pressure differentials to be determined. For example, there can be a first threshold (e.g., 0.1 MPa) for a first pressure differential (e.g., between the first and second pressures), a second threshold (e.g., 0.3 MPa) for a second pressure differential (e.g., between the first and third pressures), and a third threshold (e.g., 0.2 MPa) for a third pressure differential (e.g., between the second and third pressures).
The example controlling device 2814 illustrated in
In some examples, the pressure loop circuitry 2818 is configured to operate as a closed-loop controller based on the example pressure loop instructions. That is, the example pressure loop circuitry 2818 can continually monitor pressure measurements, calculate pressure differentials, and determine whether newly calculated differentials satisfy the threshold(s). In some examples, the pressure loop circuitry 2818 continually signals the position loop circuitry 2820 to open/close the first and/or second regulator valve(s) 2808, 2810 until the pressure differential(s) satisfy the threshold(s). For example, the pressure loop circuitry 2818 can detect that the first pressure is 1.0 MPa and the second pressure is 0.9 MPa. Given that the threshold is 0.2 MPa, the example pressure loop circuitry 2818 can send a signal the position loop circuitry 2820 to open the first regulator valve 2808 until the second pressure sensor 2804 measures a target output pressure of 1.2 MPa (assuming the first pressure remains unchanged).
The example controlling device 2814 illustrated in
The example phase separator 2712 illustrated in
The example phase separator 2712 illustrated in
The example phase separator 2712 illustrated in
The example phase separator 2712 includes the first, second, and third ports 2908-2912 to integrate the phase separator 2712 into the first and second flowlines 2506, 2508. As mentioned previously, the first and second flowlines 2506, 2508 are vacuum jacketed flowlines that can connect to other cryogenic devices (e.g., valves, tanks, other flowlines, etc.) via bayonet connections to provide seamless connection points with sufficient insulation where heat losses likely occur. A bayonet connection includes a male bayonet that fits inside of and is fixed to a female port. In some examples the male bayonets and female ports are machined to a tight tolerance (e.g., 0.001, 0.005 inches, etc.) to provide a slip fit and reduce and/or eliminate intermediary space that may not be depressurized to vacuum conditions. In some examples, the male bayonets and female ports include flanges (e.g., first flanges 2914 and second flanges 2918) with seals (e.g., O-rings, high vacuum gaskets, etc.) that are bolted together to form an air-tight coupling between the first and second flowlines 2506, 2508 and the cryogenic device (e.g., the phase separator 2712).
As illustrated in
As shown in
The example phase separator assembly 2900 illustrated in
The phase separator 2712 integrated into the first and second phase separating LH2 pump systems 2700, 2800 as described above with reference to
A flowchart representative of example machine readable instructions, which may be executed to configure processor circuitry to implement the controlling device 2814 of
The machine readable instructions described herein may be stored in one or more of a compressed format, an encrypted format, a fragmented format, a compiled format, an executable format, a packaged format, etc. Machine readable instructions as described herein may be stored as data or a data structure (e.g., as portions of instructions, code, representations of code, etc.) that may be utilized to create, manufacture, and/or produce machine executable instructions. For example, the machine readable instructions may be fragmented and stored on one or more storage devices and/or computing devices (e.g., servers) located at the same or different locations of a network or collection of networks (e.g., in the cloud, in edge devices, etc.). The machine readable instructions may require one or more of installation, modification, adaptation, updating, combining, supplementing, configuring, decryption, decompression, unpacking, distribution, reassignment, compilation, etc., in order to make them directly readable, interpretable, and/or executable by a computing device and/or another machine. For example, the machine readable instructions may be stored in multiple parts, which are individually compressed, encrypted, and/or stored on separate computing devices, wherein the parts when decrypted, decompressed, and/or combined form a set of machine executable instructions that implement one or more operations that may together form a program such as that described herein.
In another example, the machine readable instructions may be stored in a state in which they may be read by processor circuitry, but require addition of a library (e.g., a dynamic link library (DLL)), a software development kit (SDK), an application programming interface (API), etc., in order to execute the machine readable instructions on a particular computing device or other device. In another example, the machine readable instructions may need to be configured (e.g., settings stored, data input, network addresses recorded, etc.) before the machine readable instructions and/or the corresponding program(s) can be executed in whole or in part. Thus, machine readable media, as used herein, may include machine readable instructions and/or program(s) regardless of the particular format or state of the machine readable instructions and/or program(s) when stored or otherwise at rest or in transit.
The machine readable instructions described herein can be represented by any past, present, or future instruction language, scripting language, programming language, etc. For example, the machine readable instructions may be represented using any of the following languages: C, C++, Java, C#, Perl, Python, JavaScript, HyperText Markup Language (HTML), Structured Query Language (SQL), Swift, etc.
As mentioned above, the example operations of
At block 3304, the controlling device 2814 determines whether the difference between the first and second pressure measurements satisfies a threshold (e.g., a first threshold). For example, the pressure loop circuitry 2818 determines whether a first pressure differential satisfies the threshold (e.g., the first threshold). When the pressure loop circuitry 2818 determines that the first pressure differential does not satisfy (e.g., is less than) the threshold, then the pressure loop circuitry 2818 determines a target output pressure of the first regulator valve 2808 that does satisfy the threshold and transmit the second pressure measurement and the target output pressure to the position loop circuitry 2820. The operations 3300 then proceed to block 3306, where the controlling device 2814 increases the pressure output of the first regulator valve 2808. For example, the position loop circuitry 2820 determines a target position based on the current pressure and the target pressure and commands the first regulator valve 2808 to open to the target position. The example operations 3300 then return to block 3304.
When the pressure loop circuitry 2818 determines that the first pressure differential does satisfy (e.g., is greater than or equal to) the threshold (e.g., the first threshold), then the example operations 3300 proceed to block 3308, where the controlling device 2814 determines whether the difference between the first and third pressure measurements satisfies the threshold (e.g., a second threshold). For example, the pressure loop circuitry 2818 determines whether a second pressure differential satisfies the threshold (e.g., the second threshold). When the pressure loop circuitry 2818 determines that the second pressure differential does not satisfy (e.g., is less than) the threshold, then the pressure loop circuitry 2818 determines a target output pressure of the second regulator valve 2810 that does satisfy the threshold and transmit the third pressure measurement and the target output pressure to the position loop circuitry 2820. The operations 3300 then proceed to block 3310, where the controlling device 2814 increases the pressure output of the second regulator valve 2810. For example, the position loop circuitry 2820 determines a target position based on the third pressure measurement and the target pressure and commands the second regulator valve 2810 to open to the target position. The example operations 3300 then return to block 3308.
When the pressure loop circuitry 2818 determines that the second pressure differential does satisfy (e.g., is greater than or equal to) the threshold (e.g., the second threshold), then the example operations 3300 proceed to block 3312, where the controlling device 2814 determines whether the difference between the second and third pressure measurements satisfies the threshold (e.g., a third threshold). For example, the pressure loop circuitry 2818 determines whether a third pressure differential satisfies the threshold (e.g., the third threshold). When the pressure loop circuitry 2818 determines that the third pressure differential does not satisfy (e.g., is less than) the threshold, then the pressure loop circuitry 2818 determines a target output pressure of the second regulator valve 2810 that does satisfy the threshold and transmit the third pressure measurement and the target output pressure to the position loop circuitry 2820. The operations 3300 then proceed to block 3314, where the controlling device 2814 increases the pressure output of the second regulator valve 2810. For example, the position loop circuitry 2820 determines a target position based on the third pressure measurement and the target pressure and commands the second regulator valve 2810 to open to the target position. The example operations 3300 then return to block 3312.
When the pressure loop circuitry 2818 determines that the third pressure differential does satisfy (e.g., is greater than or equal to) the threshold (e.g., the third threshold), then the example operations 3300 proceed to block 3316, where the controlling device 2814 determines whether the second phase separating LH2 pump system 2800 is to continue pumping. For example, the position loop circuitry 2820 determines whether a signal to cease operation of the system 2800 has been input to the controlling device 2814. The example input may be from a user of the system 2800, a sensor in the onboard LH2 tank 2502 indicating the LH2 fuel level is substantially low, an automatic shut-off signal due to a failure in the LH2 pump 2504, etc. When the example position loop circuitry 2820 determines that the system 2800 is to continue pumping LH2, then the operations 3300 return to block 3302. When the example position loop circuitry 2820 determines that the system 2800 is not to continue pump LH2, then the operations 3300 end.
From the foregoing, it will be appreciated that example systems, methods, apparatus, and articles of manufacture have been described above that separate the hydrogen vapor phase from cryogenic liquid hydrogen fuel prior to entering an LH2 pump. Example phase separating LH2 pumping systems described above improve the efficiency and lifespan of an LH2 pump by integrating a phase separator into LH2 and GH2 vacuum jacketed flowlines leading into and out of the LH2 pump. The phase separator removes hydrogen vapor bubbles (e.g., cavities) present in LH2 extracted from onboard LH2 tanks such that cavitation damage does not occur in the LH2 pump, which allows the LH2 pump to provide a consistent flow of compressed LH2 to power systems (e.g., hydrogen powered turbine engines, etc.) and increases the functional longevity of the LH2 pump (e.g., the time between repairs, maintenance, etc.). Furthermore, example phase separating LH2 pumping systems described above improve the weight, performance, and efficiency of integrated tank system(s) 500-900 disclosed herein by increasing the amount of hydrogen vapor returned to the integrated tank system(s) 500-900, which increases the vapor pressure therein. Since vapor pressures are increased by the example phase separating LH2 pumping systems described above, the integrated tank system(s) 500-900 can rely less on a mechanical device and/or system (e.g., thermosiphon loop(s) 702, heating system(s) 704, etc.) to increase the vapor pressure, which can conserve energy and weight. Furthermore, increased vapor pressure in the LH2 tank reduces the amount of boil-off in the integrated tank system(s) 500-900 (due to the relationship between vapor pressure and boiling point), which reduces LH2 fuel loss due to evaporation. Example phase separating LH2 pumping systems described above can also increase the amount of hydrogen fuel (e.g., GH2) that is distributed to other onboard systems (e.g., power systems) from the GH2 return flowline(s) and/or the phase separator, which can reduce the weight, cost, and/or complexity of the integrated tank system(s) 500-900 by removing one or more of the GH2 extraction flowline(s) 424, 426, and/or 428 from the integrated tank system(s) 500-900 disclosed herein.
The integrated cryogenic hydrogen tank systems 500-900 described above can include GH2 extraction flowlines 424, 426, 428, to transmit hydrogen fuel (e.g., GH2) to example fuel cell power systems onboard vehicles, such as the first aircraft 100, the second aircraft 300, etc. However, in some examples, hydrogen vapor (GH2) transferred from the upper portion(s) 404 of the integrated tank system(s) 500-900 does not include sufficient densities to adequately energize example fuel cell power systems described below. Thus, in some examples, LH2 extraction flowlines 422 and/or other LH2 flowline(s) integrated into lower portion(s) 402 of the integrated system(s) 500-900 transmit LH2 to fuel cell power system(s) to provide adequate densities of hydrogen fuel.
In certain examples, a fuel cell power system for a vehicle having a propulsor is provided. The propulsor is configured to generate thrust for the vehicle and further creates a flow of compressed air ac. The fuel cell power system generally includes a fuel delivery system for providing a flow of hydrogen fuel and a fuel cell stack (e.g., including proton exchange membrane fuel cells or polymer electrolyte membrane fuel cells) configured to be located remotely from the propulsor and in airflow communication with the propulsor for receiving the flow of compressed air ac from the propulsor. The fuel cell stack further is in fluid communication with the fuel delivery system for receiving the flow of hydrogen fuel from one or more of the integrated tank systems 500-900 via the fuel delivery system.
As will be appreciated, such a configuration can allow for a significant reduction in weight and complexity for the fuel cell stack by eliminating a need for a dedicated airflow compressor and instead utilizing the flow of compressed air ac generated by the propulsor.
Additionally, in certain examples, it will be appreciated that the fuel cell power system can be configured to utilize hydrogen fuel starting at a liquid state. For example, the aircraft including the fuel cell power system can be configured to store the hydrogen fuel in the liquid state, such as within integrated cryogenic hydrogen tank systems 500-900. Such can allow for the hydrogen fuel to be stored in a more power dense manner. However, the fuel cell stack can be configured to utilize the hydrogen fuel in a gaseous state. Accordingly, in some examples, the fuel cell power system further includes a heat exchanger configured to thermally connect the flow of compressed air ac from the propulsor with the flow of hydrogen fuel, which can provide a sufficient amount of heat energy to the flow of compressed air ac to convert the flow of hydrogen fuel from the liquid phase to the gaseous phase.
In such a manner, the fuel cell power system can be configured to utilize heat within the flow of compressed air ac (from the propulsor) to provide the desired phase change of the hydrogen fuel without requiring dedicated heaters.
Referring now to
The aircraft 3510 further includes a fuel cell power system 3520 in connection with one or more of the integrated tank system(s) 500-900. In the aircraft 3510 shown in
The aircraft 3510 further includes a propulsion system 3524 that produces a propulsive thrust sufficient to propel the aircraft 3510 in flight, during taxiing operations, etc. Although the propulsion system 3524 is shown attached to the wing 3514 in
The propulsion system 3524 includes an engine, and more specifically includes a pair of engines. More specifically, still, each of the engines in the pair of engines is configured as a gas turbine engine 3526 mounted to one of the respective wings 3514 of the aircraft 3510 in an under-wing configuration through a respective pylon 3528. Each gas turbine engine 3526 can selectively generate a propulsive thrust for the aircraft 3510, and therefore is generally referred to as one or more propulsors 3515. The amount of propulsive thrust is controlled at least in part based on a volume of fuel provided to the gas turbine engines 3526 via a fuel delivery system (not shown). In some examples, the fuel is a hydrogen fuel stored substantially in a liquid phase in the integrated tank system(s) 500-900 as described above with reference to
As will be appreciated, the fuel cell power system 3520 further includes a fuel cell stack 3530. The fuel cell stack 3530 is located remotely from the propulsors 3515 (e.g., the gas turbine engines 3526 in
Referring now to
In the illustrated example of
The example turbomachine 3604 includes an outer casing 3606 that is substantially tubular and that defines an annular inlet 3608. The outer casing 3606 encases, in serial flow relationship, a compressor section 3609 including a booster or low-pressure (LP) compressor 3610 and a high-pressure (HP) compressor 3612; a combustion section 3614; a turbine section 3619 including a high-pressure (HP) turbine 3616 and a low-pressure (LP) turbine 3618; and an exhaust section 3620. The compressor section 3609, combustion section 3614, and turbine section 3619 together define at least in part a core air flow path 3621 extending from the annular inlet 3608 to the exhaust section 3620. The turbofan engine further includes one or more drive shafts. More specifically, the turbofan engine includes a high-pressure (HP) shaft or spool 3622 drivingly connecting the high-pressure turbine 3616 to the high-pressure compressor 3612, and a low-pressure (LP) shaft 3624 or spool drivingly connecting the low-pressure turbine 3618 to the low-pressure compressor 3610.
In some examples, the fan section 3602 includes a fan 3626 having a plurality of fan blades 3628 coupled to a disk 3630 in a spaced apart manner. The fan blades 3628 and disk 3630 are together rotatable about the longitudinal axis 3601 by the LP shaft 3624. The disk 3630 is covered by a rotatable front hub 3632 aerodynamically contoured to promote an airflow through the plurality of fan blades 3628. Further, an annular fan casing or outer nacelle 3634 is provided, circumferentially surrounding the fan 3626 and/or at least a portion of the turbomachine 3604. The nacelle 3634 is supported relative to the turbomachine 3604 by a plurality of circumferentially spaced outlet guide vanes 3636. A downstream section 3638 of the nacelle 3634 extends over an outer portion of the turbomachine 3604 so as to define a bypass airflow passage 3640 therebetween.
Referring still to
Moreover, as is depicted schematically, the turbofan 3600 further includes various systems to aid in the operation of the turbofan 3600 and/or an aircraft including the turbofan 3600. For example, the example turbofan 3600 can include an electric motor (not shown), which can provide electrical power to the turbofan 3600 and/or various other electronic components of the turbofan 3600 and/or an aircraft 3510 including the turbofan 3600.
Further, although not depicted, the turbofan 3600 can include one or more heat exchangers within, e.g., the turbine section 3619 or exhaust section 3620 for extracting waste heat from an airflow therethrough, such that the waste heat can be utilized to add heat to various heat sinks as waste heat during operation. Further, additionally and/or alternatively, the one or more heat exchangers can be configured to help heat hydrogen fuel H2, as explained more in depth below.
Although examples fuel cell power systems are described below as applicable to the turbofan 3600 depicted in
Referring now to
The electric propulsor assembly 3700 includes an electric motor 3706, a propulsor 3705, and a fan 3704. The electric propulsor assembly 3700 defines an axial direction A extending along a centerline axis 3702 that extends therethrough for reference, as well as a radial direction R. In the example illustration of
The fan 3704 includes a plurality of fan blades 3708 and a fan shaft 3710. The plurality of fan blades 3708 are attached to/rotatable with the fan shaft 3710 and spaced generally along a circumferential direction of the electric propulsor assembly 3700 (not shown). In some examples, the plurality of fan blades 3708 are attached in a fixed manner to the fan shaft 3710, or alternatively, the plurality of fan blades 3708 are rotatable relative to the fan shaft 3710, such as in the example depicted. For example, the plurality of fan blades 3708 each define a respective pitch axis P2, and for the embodiment depicted are attached to the fan shaft 3710 such that a pitch of each of the plurality of fan blades 3708 can be changed, e.g., in unison, by a pitch change mechanism 3711. Changing the pitch of the plurality of fan blades 3708 can increase an efficiency of the electric propulsor assembly 3700 and/or can allow the electric propulsor assembly 3700 to achieve a desired thrust profile. In such examples, the fan 3704 can be referred to as a variable pitch fan.
Moreover, the electric propulsor assembly 3700 includes a fan casing or outer nacelle 3712, attached to a core 3714 of the electric propulsor assembly 3700 through one or more struts or outlet guide vanes 3716. The outer nacelle 3712 substantially completely surrounds the fan 3704, and particularly the plurality of fan blades 3708. Accordingly, the electric propulsor assembly 3700 can be referred to as a ducted electric fan.
Referring still particularly to
The fan shaft 3710 is supported by one or more bearings 3718, such as one or more roller bearings, ball bearings, and/or another type of bearing. Additionally, the electric motor 3706 can be an in-runner electric motor (e.g., including a rotor positioned radially inward of a stator), or alternatively can be an outrunner electric motor (i.e., including a stator positioned radially inward of a rotor), or alternatively, still, can be an axial flux electric motor (e.g., with the rotor neither outside the stator nor inside the stator, but rather offset from it along the axis of the electric motor).
The electric propulsor assembly 3700 can also be connected to an electric energy storage unit (not shown) and/or an electric machine (also not shown). In some examples, the electric propulsor assembly 3700 is electrically connectable through one or more electric lines 3760 of a power bus 3758. For example, the power bus 3758 can include various switches or other power electronics movable to selectively connect the various components of the hybrid-electric propulsion system 3750 via electronic connections.
It some examples, the electric propulsor assembly 3700 is integrated into an aircraft, e.g., aircraft 3510 of
Referring now to
As illustrated in
Additionally, the fuel cell power system 3800 is arranged in airflow communication with the propulsor 3820 for receiving the flow of compressed air ac and is also in fluid communication with the fuel delivery system 3812 for receiving the flow of hydrogen fuel. The airflow communication between the fuel cell power system 3800 and the propulsor 3820 can include one or more airflow ducts 3813 (see 3813a-3813h). The one or more airflow ducts 3813 can meet at one or more junctures 3811 (see 3811a-3811f) and can also have one or more valves 3815 (see 3815a-3815b) to control the airflow. The fluid communication with the fuel delivery system 3812 can include one or more inlet/outlet lines.
Generally, the fuel delivery system 3812 is configured to provide a flow of hydrogen fuel to the fuel cell stack 3840 and a compressed airflow delivery system 3818 of the fuel cell power system 3800 is configured to provide a flow of compressed air ac from the propulsor 3820 to the fuel cell stack 3840. The fuel cell stack 3840 is located remotely from the propulsor 3820 as described above and is in airflow communication with the propulsor 3820 through the compressed airflow delivery system 3818 for receiving the flow of compressed air ac from the propulsor 3820. The fuel cell stack 3840 is further in fluid communication with the fuel tank 3810 through the fuel delivery system 3812 for receiving the flow of hydrogen fuel from the fuel delivery system 3812. Additionally or alternatively, the fuel cell stack 3840 can receive hydrogen fuel from the integrated cryogenic hydrogen tank system(s) 500-900 described above. The fuel tank 3810 can be configured to hold the hydrogen fuel at least partially within the liquid phase and can further be configured to provide hydrogen fuel to the fuel cell power system 3800 substantially completely in the liquid phase, such as completely in the liquid phase. For example, the fuel tank 3810 can define a fixed volume, such that as the fuel tank 3810 provides hydrogen fuel to the fuel cell power system 3800 substantially completely in the liquid phase, a volume of the liquid hydrogen fuel in the fuel tank 3810 decreases, and the volume is made up by, e.g., gaseous hydrogen.
Additionally, the fuel cell stack 3840 can be a proton exchange membrane cell stack. As used herein, the term “proton exchange membrane cell stack” refers to a grouping of multiple fuel cells that are connected in series to achieve a useful voltage, and where each fuel cell has multiple layers. In some examples, the outermost layers are flow plates; followed by two sealing layers that are an anode or a cathode and through which hydrogen and oxygen particles flow through; with two gas diffusion layers on either side of a proton conducting electrolyte (e.g., a proton exchange membrane) in the middle of the fuel cell. Generally, the proton exchange membrane fuel stack operates at an optimal temperature of 40-90° C.; however, the fuel cell stack 3840 and/or the proton exchange membrane fuel stack itself can be altered to operate at additional temperatures.
The fuel tank 3810 and fuel cell power system 3800 can include a variety of supporting structure to facilitate storing and/or transporting the hydrogen fuel in such a manner. For example, the fuel delivery system 3812 is provided for transporting the hydrogen fuel from the fuel tank 3810 to one or more other components of the fuel cell power system 3800. Although not depicted in
Additionally, the fuel cell power system 3800 includes a heat exchanger 3830 in communication with the fuel delivery system 3812 and the compressed airflow delivery system 3818 for transferring heat from the flow of compressed air ac to the flow of hydrogen fuel. In such a manner, the flow of compressed air ac can heat the hydrogen fuel from the liquid phase to a gaseous phase, to a supercritical phase, or both. In some examples, the heat exchanger 3830 can be a first heat exchanger, and the fuel cell power system 3800 can further include a second heat exchanger configured to output the hydrogen coolant into first heat exchanger. The fuel cell power system 3800 can be modified to include a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger, etc.
As shown in
Also as shown, the fuel cell power system 3800 further includes a first valve 3815a in fluid communication with the fuel delivery system 3812 at a location upstream of the heat exchanger 3830 for metering a flow of the hydrogen fuel through the fuel delivery system 3812 to the heat exchanger 3830 and subsequently to the fuel cell stack 3840. The first valve 3815a controls the amount of hydrogen entering the heat exchanger 3830 from the engine 3804 and/or from the fuel tank 3810. Similarly, a second valve 3815b is positioned at a location upstream of the battery heat exchanger 3860 for controlling the flow of the hydrogen fuel into the battery heat exchanger 3860.
Turning now to a fuel power process of the fuel cell power system 3800 specifically, the fuel delivery system 3812 includes one or more airflow ducts 3813 to facilitate the flow as described herein. In some examples, such as the example of
In the illustrated example, a flow f of hydrogen fuel from the fuel tank 3810 is split at a first juncture 3811a into a first flow f1 through a first duct 3813a and a second flow f2 through a second duct 3813b, as shown in
The second flow f2 is provided through a second valve 3815b to the battery heat exchanger 3860. In some examples, the fuel cell power system 3800 includes a power output assembly 3865 configured to receive electrical power from the fuel cell stack 3840. In some examples, the power output assembly 3865 can include a battery (not shown) or other similar structure for storing at least a portion of the electrical power generated prior to transferring some or all of such electrical power for useful work. The battery heat exchanger 3860 is in thermal communication with the power output assembly 3865 and can reduce a temperature of the power output assembly 3865. Reduced temperatures can help the power output assembly 3865 operate in a desired and/or more efficient manner and can assist with heating the flow of hydrogen fuel from the liquid state to the gaseous state.
The second flow f2 of hydrogen fuel from the battery heat exchanger 3860 is provided through a fourth duct 3813d, where the second flow f2 splits into another two flows, e.g., a primary flow f3 and a secondary flow f4, at a third juncture 3811c. The primary flow f3 is provided to the heat exchanger 3830 and flows through a fifth duct 3813e. The secondary flow f4 is provided through a sixth duct 3813f to the fuel cell stack 3840 to cool the fuel cell stack 3840, through a stack inlet 3842 and out a stack outlet 4144, before rejoining the primary flow f3 at a fourth juncture 3811d.
Referring still to
In some examples, the fuel cell power system 3800 further includes a startup heater 3880. As depicted, the startup heater 3880 is positioned downstream of the heat exchanger 3830 and upstream of the fuel cell stack 3840 for heating the flow f of hydrogen fuel provided to the fuel cell stack 3840 through an eighth duct 3813h. In particular, when the engine 3804 and/or aircraft 3510 is not yet being operated, e.g., when the engine 3804 and/or aircraft 3510 is in startup and/or pre-operation mode, the startup heater 3880 can be used to warm the hydrogen fuel before the hydrogen fuel is provided to the fuel cell stack 3840. Even in embodiments where the vehicle is not in startup and/or pre-operation mode, the startup heater 3880 can be used to heat the hydrogen fuel to a desired temperature before the hydrogen fuel is provided to the fuel cell stack 3840.
Additionally, the fuel cell power system 3800 includes a recirculation system 3814 directly downstream of the fuel cell stack 3840, where the recirculation system 3814 includes a separator 3772 and a recirculation pump 3770. The recirculation system 3814 can further include an exhaust water system 3816. The separator 3772 separates exhaust water (denoted as H2O) from the hydrogen fuel and ejects it through an exhaust section 3922 as part of the exhaust water system 3816 (see also exhaust section 3922 of
In particular, the hydrogen fuel, as it travels through the fuel cell power system 3800, cools the heat exchanger 3830, along with some other heat exchangers, e.g., the engine heat exchangers 3808 in the engine 3804, in one or more fuel cooled oil coolers of the aircraft 3510, and/or at multiple locations within each fuel cell of the fuel cell stack 3840. The hydrogen fuel can additionally cool at least part of the battery heat exchanger 3860, the humidifier 3870, and/or another component of a vehicle (such as aircraft 3510 of
Using the hydrogen fuel from the fuel tank 3810 to cool the fuel cell power system 3800 and/or the aircraft 3510 increases efficiency in the fuel cell power system 3800 and the aircraft 3510 itself. Additionally, the fuel cell power system 3800 can remove the need for an air compressor and/or a coolant pump. Finding a dual purpose for the hydrogen fuel (e.g., to fuel and to cool the vehicle) also eliminates or reduces the need for an outside coolant. The hydrogen fuel can further lower noise and vibrations of the fuel cell power system 3800.
Hydrogen fuel defines a relatively low boiling point, such that when the hydrogen fuel is provided through the fuel delivery system 3812 and/or the cooling system in the liquid phase, hydrogen fuel can freeze a gas within the fuel delivery system 3812. Accordingly, the heat exchanger 3830 is provided to receive a flow of the hydrogen fuel in the liquid phase and heat the hydrogen fuel from the liquid phase to a gaseous phase or to a supercritical phase, such that the heated hydrogen fuel does not freeze the gas within the fuel power process.
Referring still to
Generally, the compressed airflow process is provided through the compressed airflow delivery system 3818. The compressed airflow delivery system 3818 enters into the fuel cell power system 3800 from the engine 3804 of the propulsor 3820. In some examples, e.g., where the propulsor 3820 includes a turbomachine (e.g., the turbomachine 3604 of
Humidifiers provide heat and humidity to the incoming oxidant or hydrogen fuel stream of fuel cells and can improve an overall system performance and reliability. Without humidification, the fuel cell membrane of the fuel cell stack 3840 can dry out, which can reduce a proton transport in the fuel cell stack 3840 and can decrease an oxygen reduction reaction at a cathode of a fuel cell within the fuel cell stack 3840.
Referring now to
The schematic drawing shows that air α enters into the compressor section 3909 and flows out of an exhaust section 3922, which can be similar to the exhaust section 3620 of
Referring still to
Referring now to
Referring particularly to
Referring now to
Referring now to
However, for the example of
Referring still to
The second flow f72 provides the hydrogen fuel through a second duct 4213b to a first valve 4215a and into the hydrogen/coolant heat exchanger 4206, before rejoining the first flow f71 at the second juncture 4211b. The rejoined flow, e.g., a flow f71, including the first flow f71 and the second flow f72 then provides the hydrogen fuel through a third duct 4213c to a second valve 4215b and into the heat exchanger 4230, where the heated hydrogen fuel is subsequently provided to the fuel cell stack 4240 for electric power generation, as described above.
After exiting the fuel cell stack 4240 through a stack outlet 4244, the flow f7 flows through the humidifier 4270. The humidifier 4270 humidifies the coolant and circulates it to the coolant pump 4219 through a fourth duct 4213d as part of a coolant cooling system 4222. From the coolant pump 4219, the coolant is then provided to the hydrogen/coolant heat exchanger 4206, before flowing through a third juncture 4211c, where the flow of the coolant is split into a first coolant flow f73 and a second coolant flow f74. The first coolant flow f73 provides the coolant through a fifth duct 4213e to the heat exchanger 4230 and rejoins the second coolant flow f74 before flowing through the humidifier 4270. The second coolant flow f74 provides the coolant through a sixth duct 4213f to a startup heater 4280, and then to both the battery heat exchanger 4260 and the fuel cell stack 4240 in a first stream f75 and a second stream f76, respectively. The first stream f75 and the second stream f76 of the second coolant flow f74 then rejoin upstream of the fourth juncture 4211d, before rejoining the first coolant flow f73 at the fourth juncture 4211d and entering the humidifier 4270.
Additionally, the fuel cell power system 4200 includes a recirculation system 4214 directly downstream of the fuel cell stack 4240, where the recirculation system 4214 includes a separator 4272 and a recirculation pump 4274. The recirculation system 4214 can further include an exhaust water system 4216. The separator 4272 separates exhaust water (denoted as H2O) from the hydrogen fuel and ejects it through an exhaust section 4224 as part of the exhaust water system 4216.
Referring now to
However, for the embodiment of
A coolant cooling system 4322 provides the coolant from the coolant pump 4320 to the startup heater 4380. The startup heater 4380, along with the hydrogen fuel provided from a first valve 4315a through the second duct 4313b is flowed into the hydrogen/coolant heat exchanger 4306. The coolant then reaches a third juncture 4311c, where it splits into two flows: a first coolant flow f83 and a second coolant flow f84. The first coolant flow f83 provides the coolant to a heat exchanger 4330 through a third duct 4313c before rejoining the second coolant flow f84. The second coolant flow f84 provides coolant through a fourth duct 4313d to a battery heat exchanger 4360 and through a fifth duct 4313e to a fuel cell stack 4340 (e.g., in a stack inlet 4342 of the fuel cell stack 4340 and out a stack outlet 4344 of the fuel cell stack 4340). The coolant from the battery heat exchanger 4360 and to the fuel cell stack 4340 is rejoined into the second coolant flow f84, before rejoining the first coolant flow f83 at the fourth juncture 4311d. From the fourth juncture 4311d, the coolant is provided to a humidifier 4370, from which the coolant is then recirculated to the coolant pump 4320 as part of the coolant cooling system 4322.
Also for the embodiment of
The second fuel delivery system 4312b provides gaseous hydrogen through a second valve 4315b to meet the hydrogen fuel from the first fuel delivery system 4312a at the second juncture 4311b. At least a portion of the hydrogen fuel is provided from the second juncture 4311b to the coolant pump 4320 via the coolant cooling system 4322. The remaining portion of the hydrogen fuel is provided from the second juncture 4311b to a third valve 4315c located upstream of the heat exchanger 4330. The hydrogen fuel then generally follows the same path as described with reference to fuel delivery system 3812 of
Referring now to
The fuel cell power system 4400 includes a power converter 4464 and at least one electric machine 4466. Similar to the fuel cell power system 3800 of
The second flow f2 of hydrogen fuel is provided through a second duct 4413b and a second valve 4415b to a battery heat exchanger 4460. The battery heat exchanger 4460 is in thermal communication with a power output assembly 4465 for reducing a temperature of the power output assembly 4465. The battery heat exchanger 4460 is further in fluid communication with the power converter 4464, which in turn is in electrical communication with the at least one electric machine 4466. The power converter 4464 and the at least one electric machine 4466, or both, are in thermal communication with the fuel delivery system for transferring heat with the flow of hydrogen fuel through the fuel delivery system. The second flow f2 passes through a fourth duct 4415d to the power converter 4464, and is then passed to a third juncture 4411c, where it splits into a primary flow f3 and a secondary flow f4. In such a manner, the hydrogen fuel can cool the power converter 4464 (and although not depicted schematically in
Accordingly, for the example of
Referring now to
Generally, the fuel cell power system 4500 has a fuel delivery system similar to the fuel delivery system 4412 described above with respect to a fuel delivery system 4412 of
In still other examples, e.g., the example of
The rest of the fuel cell power system 4600 operates in a similar manner to the fuel cell power systems described in other figures; as such, the same or similar reference numbers may refer to the same or similar parts in earlier figures.
Referring now to
Although the method 4700 is described herein with respect to a hydrogen aircraft and with a fuel cell stack, e.g., a proton exchange membrane fuel cell stack, the method 4700 can additionally and/or alternatively operate with another fuel cell power system for another type of vehicle and/or engine.
At block 4710, the method 4700 includes, operating the propulsor, such as the propulsor 3820 of
At block 4720, the method 4700 includes providing the flow of compressed air αc to the fuel cell power system. As described above, the flow of compressed air αc can be created by a compressor section (e.g., a low-pressure compressor), a bypass airflow passage, or both.
At block 4730, the method 4700 further includes, providing a flow of hydrogen fuel from a fuel delivery system to one or more engine heat exchangers positioned within the engine. The hydrogen fuel is provided from the fuel tank to the engine, where it is heated by the one or more engine heat exchangers of the engine. The hydrogen fuel within the fuel tank is at least partially in a liquid phase, and the fuel cell power system is configured to provide hydrogen fuel from the integrated cryogenic hydrogen tank systems described above substantially completely in the liquid phase. Moreover, for the example method 4700 depicted, it will be appreciated that providing the flow of hydrogen fuel from the integrated tank systems via the fuel delivery system can include metering the flow of hydrogen fuel with a flow metering unit, such as a valve.
Further, as mentioned previously, the flow of hydrogen fuel includes a first flow of hydrogen fuel and a second flow of hydrogen fuel. The method 4700 can additionally include providing the first flow of hydrogen fuel from a first tank in the integrated tank system and providing the second flow of hydrogen fuel from a second tank in the integrated tank system, via the fuel delivery system, directly to a fuel cell stack of the fuel cell power system.
At block 4740, the method 4700 includes providing the flow of hydrogen fuel from the one or more engine heat exchangers to a heat exchanger located upstream of the fuel cell stack. More specifically, as described above in reference to
At block 4750, the method 4700 includes exchanging heat between the flow of compressed air and the flow of hydrogen fuel with the heat exchanger located upstream of the fuel cell stack. As the compressed air typically leaves the low-pressure compressor, the bypass airflow passage, or both, extremely hot, the heat exchanger exchanges heat between the hot compressed air and the cold liquid hydrogen fuel. The cooled compressed air is then humidified into humidified compressed air by the humidifier before flowing into the fuel cell stack.
The fuel cell power system operated in accordance with the example method 4700 described above can allow for utilization of a hydrogen fuel as a fuel source for the engine, and more particularly can utilize storage of the hydrogen fuel in a liquid phase, while providing hydrogen fuel in a gaseous phase to the engine for combustion.
In some examples, e.g., as mentioned with respect to the fuel cell power system 3800 in
In some other examples, when the aircraft is in startup and/or pre-operation mode, the method 4700 can include using a startup heater to warm the hydrogen fuel before the hydrogen fuel is flowed to the fuel cell stack. In some examples, the startup heater can further heat at least a portion of the engine and/or the compressed air αc. Further, the startup heater can be a forced air heater, where the startup heater provides compressed air to the fuel cell stack. As discussed above, the startup heater is used when the aircraft is not yet operating.
In some other examples, e.g., where the fuel cell system is the fuel cell system 4300 described with reference to
Furthermore, in examples where the fuel cell system further includes a power converter and at least one electric machine, e.g., as shown in
In some examples, the fuel cell system includes a pump motor operably coupled to a liquid hydrogen fuel pump and a power converter, as described in
In some other examples, the fuel cell power system includes a power converter and a liquid hydrogen fuel pump fluidly coupled to a fuel tank and operably coupled to a pump motor. This fuel cell power system is shown in
It should be appreciated that the fuel tanks (e.g., the fuel tanks 3648, 3810, 4210, 4310, 4410, 4510, 4610, etc.) described above may be implemented as one or more of the integrated tank systems 500-900 of
As described above, example fuel cell power systems can be used to power turbine engines on aircraft, such as aircraft 3510 of
Example integrated cryogenic hydrogen tank systems described above can experience uncontrolled leakages due to improperly attached bayonet connections, faulty valve components, damaged electronic connections, etc. Since more tanks, flowlines, valves, etc. are utilized in the example integrated tank system(s) 500-900 compared to single-tank hydrogen aircraft, there can be a greater likelihood of hydrogen fuel leakages. Example monitoring systems can be included in the integrated tank system(s) 500-900 to detect such leakages and ensure that the integrated tank system(s) 500-900 operate properly without losing excessive fuel due to one or more leaks.
As mentioned previously, liquid hydrogen can be supplied from the integrated tank system(s) 500-900 to an engine of hydrogen aircraft. In addition to using liquid hydrogen, fuel distribution systems can deliver gaseous hydrogen at required pressure(s) and/or flow rate(s) from the integrated tank system(s) 500-900 to a combustor to meet the transient performance requirements needed to assure that the engine meets both transient and cruise condition requirements. However, the fuel flow rate for an aircraft varies significantly during the flight mission. For example, the highest fuel flow rate is required during takeoff, which is approximately four times the fuel flow rate at cruise altitude.
Methods and apparatus described below incorporate liquid hydrogen (LH2), cryo-compressed hydrogen (CCH2), and/or gaseous hydrogen (GH2) into fuel distribution systems (e.g., a LH2 fuel distribution system, a GH2 fuel distribution system, a CCH2 fuel distribution system, etc.) of a gas turbine engine. Examples described below include a system that continuously monitors the health of the integrated tank system(s) 500-900 and the fuel distribution system(s) of a gas turbine engine associated with an aircraft. In some examples described below, pressure, temperature, and/or liquid level sensors determine the mass flow rate of the hydrogen in and/or out of the from the integrated tank system(s) 500-900 as a function of time and a flowmeter determines the outflow of hydrogen into the combustor of the gas turbine engine. In some examples described below, the system can also determine the outflow of hydrogen vented via a vent valve. Examples described below compare the flow of hydrogen from the from the integrated tank system(s) 500-900 and the outflowing hydrogen to determine a mass loss rate from the fuel distribution system. Examples described below can also be utilized to analyze the health of a fuel distribution system including other hydrogen fuel sources, such as the integrated cryogenic hydrogen tank system(s) 500-900 described above, one or more cryo-compressed hydrogen tank(s), etc.
In some examples described below, the average mass loss rate over a period of time can be compared to a plurality of thresholds. In some examples described below, when the mass loss rate is greater than zero over the period, the health monitoring system can conclude a leak is present in the fuel distribution system. In some such examples described below, the health monitoring system can identify the portion of the system including the leak and isolate the section to prevent additional hydrogen leaking. In some examples described below, when the mass loss rate is negative over the period (e.g., indicating a gain of mass, etc.), the health monitoring system can conclude that the sensors of the system need to be recalibrated. In some examples described below, when the mass loss rate is zero, the health monitoring system can conclude there are no health issues with the engines. In some examples described below, the system can be used to calibrate the flowmeter of the combustor.
Although the aircraft 4800 shown in
In
The examples of fuel tanks and/or integrated tank systems described below can also be applicable to other applications where hydrogen is used as a fuel in the aircraft 4800. The embodiments described below also can be applicable to engine(s) other than gas turbine engines.
While the gas turbine engine 4806 is an example of a power generator for powering the aircraft 4800 using hydrogen as a fuel, hydrogen may also be used as a fuel for other power generators. For example, a power generator can be a fuel cell (e.g., hydrogen fuel cell power systems described above with reference to
The first fuel distribution system 4900 of
The flows from the GH2 tank bank 4905 and the LH2 tank 4906 are tracked by one or more sensor(s), which sense various operability parameters of the first fuel distribution system 4900 of
The GH2 tank bank 4905 stores a first portion of hydrogen fuel in a gaseous phase and the LH2 tank 4906 stores a second portion of hydrogen fuel in a liquid phase. The GH2 tank bank 4905 can be configured to store the first portion of hydrogen fuel at an increased pressure to reduce a necessary size of the GH2 tank bank 4905 within an aircraft. For example, the GH2 tank bank 4905 can be configured to store the first portion of hydrogen fuel at a pressure from about 100 bar up to about 1,000 bar. The GH2 tank bank 4905 can be configured to store the first portion of the hydrogen fuel at a temperature within about 50° C. of an ambient temperature, or between about −50° C. and about 100° C. In some examples, the GH2 tank bank 4905 can be configured as a plurality of GH2 tank bank 4905 to reduce an overall size and weight that would otherwise be needed to contain the desired volume of the first portion of hydrogen fuel in the gaseous phase at the desired pressures. Gaseous hydrogen delivery can also include an example three-way boil-off valve 4913 defining an example first input 4916, an example second input 4918, and an example output 4920.
In the example of
The example first fuel distribution system 4900 includes a gaseous hydrogen delivery assembly (GHDA) flow regulator 4926. The GHDA flow regulator 4926 can be configured as an actively controlled variable throughput valve configured to provide a variable throughput ranging from 0% (e.g., a completely closed off position) to 100% (e.g., a completely open position), as well as a number of intermediate throughput values therebetween. In
In the example of
In the example of
To prevent an internal pressure within the LH2 tank 4906 from exceeding a pressure threshold, the first fuel distribution system 4900 of
The LH2 tank 4906 can be connected to an example vacuum jacketed (VJ) flowline(s) 4956, which is in connection with the pump 4946. In some examples, the VJ flowline(s) 4956 can include a flow control valve. The pump 4946 is configured to provide a flow of hydrogen fuel in the liquid phase from the LH2 tank 4906 through the liquid hydrogen delivery assembly 4902. Operation of the pump 4946 can be modulated (e.g., increased, decreased, etc.) to effectuate a change in a volume of the hydrogen fuel through the liquid hydrogen delivery assembly 4902 and to an example regulator assembly 4957 and the engine 4909. The pump 4946 can be any suitable pump configured to provide a flow of liquid hydrogen fuel. In some examples, the pump 4946 is a cryogenic pump. In some examples, the pump 4946 is the primary pump for the liquid hydrogen delivery assembly 4902 (e.g., provides a majority of a motive force available for providing a flow of liquid hydrogen through the liquid hydrogen delivery assembly 4902, etc.). In some examples, at least about 75% of the motive force available for providing a flow of liquid hydrogen through the liquid hydrogen delivery assembly 4902 can be provided by the pump 4946. The pump 4946 can generally define a maximum pump capacity and a minimum pump capacity (each in kilograms per second). A ratio of the maximum pump capacity to the minimum pump capacity can be referred to as a turndown ratio of the pump 4946. In some examples, the pump 4946 can define a turndown ratio of at least 1:1 and up to about 6:1. In the example of
The heat exchanger 4948 is located downstream of the pump 4946 and a flow control valve (not illustrated) and is configured to convert a portion of the hydrogen fuel through the liquid hydrogen delivery assembly 4902 from the liquid phase to a gaseous phase. In the illustrated example of
In the example of
The flowmeter 4964 of the regulator assembly 4957 can sense data indicative of a mass flow rate of hydrogen fuel through the regulator assembly 4957. For example, the flowmeter 4964 can sense data indicative of one or more of a temperature of the gaseous hydrogen fuel flowing therethrough and a pressure of the gaseous hydrogen fuel flowing therethrough. In some examples, data from the flowmeter 4964 can be utilized to control the regulator 4966 to ensure a desired amount of fuel is provided to the combustor 4910 of the engine 4909. The regulator 4966 can be configured as an actively controlled variable throughput valve configured to provide a variable throughput ranging from 0% (e.g., a completely closed off position) to 100% (e.g., a completely open position), as well as a number of intermediate throughput values therebetween. In some examples, the regulator 4966 is in connection with the combustor 4910 of the engine 4909 via a flow control valve (not illustrated). In the illustrated example of
The CCH2 tank 5002 stores hydrogen at cryogenic temperatures (between 40 and 100 K) and relatively high pressures. The CCH2 tank 5002 includes an insulated outer shell that permits hydrogen to be held cryogenic temperatures, which increases the volume of hydrogen that can be stored in the tank 5002. Additionally, the CCH2 tank 5002 holds hydrogen at a comparatively higher pressure than the LH2 tank 4906 of
In the example of
In the illustrated example of
In the example of
The three-way automatic valve 5014 can be an active valve, such that an amount of gaseous hydrogen fuel provided to the first output 5018, as compared to the amount of gaseous hydrogen fuel provided from the second output 5020, from the input 5016, can be actively controlled. In some examples, the three-way automatic valve 5014 can be a passive valve. In the example of
The sensor interface circuitry 5102 receives sensor data from the sensors of the fuel distribution system. For example, the sensor interface circuitry 5102 can receive sensor data from the sensors 4912, 4914, 4928, 4960, 4967, 4968, 4980 of the first fuel distribution system 4900 of
The mass flow determiner circuitry 5104 determines the mass flow of hydrogen through the fuel distribution system via the accessed sensor data. For example, the mass flow determiner circuitry 5104 can determine the mass flow from the GH2 tank bank 4905 using data from the first sensor 4912 to determine the density of the H2 in tank as a function of temperature and pressure:
ρ1(t)=f(P1(t),T1(t)) (1)
m
1(t)=ρ1(t)VTANKBANK (2)
wherein ρ1 is the density of the gaseous hydrogen of the GH2 tank bank 4905, t is time, P1 is the pressure for the hydrogen as measured by the first sensor 4912, T1 is the temperature of the hydrogen of the GH2 tank bank 4905 as measured by the first sensor 4912, m1(t) is the mass of the GH2 tank bank 4905 as a function of time (e.g., the mass flow from the GH2 tank bank 4905 into the first fuel distribution system 4900, etc.), and VTANKBANK is the total volume of the GH2 tank bank 4905. Accordingly, using temperature and pressure sensor data from the first sensor 4912 and the equations (1) and (2), the mass flow determiner circuitry 5104 can determine the mass flow from the GH2 tank bank 4905. In some examples, the density of the tank bank can be the average density of the hydrogen across the different tanks of the GH2 tank bank 4905. In such examples, the density can be determined using sensors associated with the total outflow of the GH2 tank bank 4905. Additionally or alternatively, the density and mass flow from the GH2 tank bank 4905 can be determined on a per tank basis, using flow sensors associated with each tank.
The mass flow determiner circuitry 5104 can determine the mass flow from the LH2 tank 4906 of
ρ2L(t)=f(T2(t)) (3)
ρ2V(t)=f(T2(t)) (4)
m
2(t)=(5)2L(t)VLH2TANKL2(t)+ρ2V(t)VLH2TANK(1−L2(t)) (5)
wherein ρ2L is the density of the liquid hydrogen of the LH2 tank 4906, ρ2V is the density of the vaporous hydrogen of the LH2 tank 4906, T2 is the temperature of the hydrogen of the LH2 tank 4906 as measured by the second sensor 4914, m2(t) is the mass of the LH2 tank 4906 as a function of time (e.g., the mass flow from the LH2 tank 4906 into the first fuel distribution system 4900, etc.), VLH2TANK is the volume of the LH2 tank 4906, and L2 (t) is the liquid level of the LH2 tank 4906. Accordingly, using temperature and liquid level sensor data from the second sensor 4914 and the equations (3), (4) and (5), the mass flow determiner circuitry 5104 can determine the mass flow from the LH2 tank 4906. In some examples, the T2 can be assumed to be the saturation temperature of hydrogen.
The mass flow determiner circuitry 5104 can determine the mass flow from the CCH2 tank 5002 of
wherein ρ1(t) is the density of the hydrogen in the CCH2 tank 5002 as a function of time, P1(t) is the pressure of the hydrogen in the CCH2 tank 5002 as a function of time as provided by the first sensor 5010, T1(t) is the temperature of the hydrogen in the CCH2 tank 5002 as a function of time as provided by the first sensor 5010, m1(t) is the mass of the hydrogen in the CCH2 tank 5002 as a function of time, V is the volume of the CCH2 tank 5002, t1 is a first time, t2 is a second time, m1(t1) is the mass of hydrogen in the CCH2 tank 5002 at the first time, m2(t2) is the mass of hydrogen in the CCH2 tank 5002 at the second time, and {dot over (m)}(t12) is the average mass flow rate of hydrogen out of the CCH2 tank 5002 between the first time and the second time. In other examples, the mass flow determiner circuitry 5104 can determine the mass flow rate out of the CCH2 as a function of time by any other suitable means (e.g., a flowmeter, etc.).
In some examples, the mass loss determiner circuitry 5106 can determine the flow of hydrogen into the combustor 4910 (e.g., in the first fuel distribution system 4900 of
wherein t1 is a first time when a vent valve 4974 is opened, t2 is a second time when a vent valve 4974 is closed, mvent is mass of hydrogen vented through the vent valve 4974, {dot over (m)} is exhaust rate of hydrogen as a function of time, kD is a discharge coefficient of the nozzle associated with the vent valve 4974 (e.g., ˜0.595, etc.), A is the area of the orifice of the vent valve 4974, ρ3 is the density of hydrogen in the second GH2 buffer tank 4962 (e.g., can be determined based on the pressure and temperature of the hydrogen in the second GH2 buffer tank 4962, etc.), P3 is the pressure in the second GH2 buffer tank 4962, Pamb is the ambient pressure, and k is 1.41, the specific heat capacity ratio of H2. In some examples, the mass flow exhausted via the vent valve 5031 of
The mass loss determiner circuitry 5106 determines the mass loss from the fuel distribution systems 4900, 5000. For example, the mass loss determiner circuitry 5106 can compare the mass inflows (e.g., from the LH2 tank 4906, from the GH2 tank bank 4905, etc.) and mass outflows (e.g., into the combustor 4910, vented from the second GH2 buffer tank 4962, etc.). For example, the mass loss determiner circuitry 5106 can determine the mass balance of the first fuel distribution system 4900 of
∫t
ML(t2)=m2(t1)−m2(t2)+m1(t2)+m5(t1)−m5(t2)+m7(t1)−m7(t2)−mvent(t2)+mvent(t1)−∫t
wherein {dot over (m)}flow is the mass flow rate out of the first fuel distribution system 4900 (as measured by the flowmeter 4964 and/or sixth sensor 4968), m1(t1) is the mass of hydrogen associated with the GH2 tank bank 4905 at the first time, m1(t2) is the mass of hydrogen associated with the GH2 tank bank 4905 at the second time, m2(t1) is the mass of hydrogen associated with the LH2 tank 4906 at the first time, m2(t2) is the mass of hydrogen associated with the LH2 tank 4906 at the second time, m5(t1) is the mass of hydrogen associated with the first GH2 buffer tank 4954 at the first time, m5(t2) is the mass of hydrogen associated with the first GH2 buffer tank 4954 at the second time, m7(t1) is the mass of hydrogen associated with the second GH2 buffer tank 4962 at the first time, m7(t2) is the mass of hydrogen associated with the second GH2 buffer tank 4962 at the second time, mvent(t2) is the mass of hydrogen vented through the vent valve 4974 at the second time, mvent(t1) is mass of hydrogen vented through the vent valve 4974 at the first time, and ML(t2) is the cumulative mass loss between the first time and the second time.
The mass loss determiner circuitry 5106 can determine the mass balance of the second fuel distribution system 5000 of
∫t
ML(t2)=m1(t1)−m1(t2)+m4(t1)−m4(t2)−mvent(t2)+mvent(t1)−∫t
wherein {dot over (m)}flow is the mass flow rate out of the second fuel distribution system 5000 (as measured by the flowmeter 4964 and/or the fifth sensor 5030), m1(t1) is the mass of the hydrogen in the CCH2 tank 5002 at the first time, m1(t2) is the mass of the hydrogen in the CCH2 tank 5002 at the second time, m4(t1) is the mass of hydrogen associated with the fifth sensor 5030 at the first time, mvent(t2) is the mass of hydrogen vented through the vent valve 4974 at the second time, mvent(t1) is mass of hydrogen vented through the vent valve 4974 at the first time, ML(t2) is the cumulative mass loss of the second fuel distribution system 5000 between the first time and the second time, and m4(t2) is the mass of hydrogen associated with the fifth sensor 5030 at the second time. As such, the mass loss determiner circuitry 5106 can determine the mass loss rate associated with the first fuel distribution system 4900 of
The threshold comparator circuitry 5108 compares the determined mass loss rate to one or more thresholds. For example, the threshold comparator circuitry 5108 can determine if the determined mass loss rate satisfies (e.g., exceeds, etc.) a first threshold (e.g., a warning threshold, etc.). Additionally or alternatively, the threshold comparator circuitry 5108 can determine if the determined mass loss rate satisfies (e.g., is less than, etc.) a second threshold (e.g., a recalibration threshold, etc.). In some examples, the first threshold and the second threshold can be the same (e.g., zero, etc.). In such examples, when the mass loss rate is greater than the single threshold, the threshold comparator circuitry 5108 can trigger actions (e.g., issuing a warning, isolating the leak, etc.) associated with satisfying the first threshold and when the mass loss rate is less than the single threshold, the threshold comparator circuitry 5108 can trigger actions associated with satisfying the second threshold (e.g., generating a notification to recalibrate the sensors, etc.).
The fuel distribution system interface circuitry 5110 interfaces with the first fuel distribution system 4900 and/or the second fuel distribution system 5000. For example, if the threshold comparator circuitry 5108 determines the mass loss rate satisfies the first threshold, the fuel distribution system interface circuitry 5110 can, via the sensor data, determine where in the fuel distribution system (e.g., the first fuel distribution system 4900 and/or the second fuel distribution system 5000, etc.). In some examples, the fuel distribution system interface circuitry 5110 can present to a user of the fuel distribution system (e.g., an operator of the aircraft 4800, etc.) an indication of where the detected leak is. Additionally or alternatively, the fuel distribution system interface circuitry 5110 can isolate the detected leak by closing a valve, closing a regulator, routing hydrogen through an alternative part of the fuel distribution system, etc.
The notification generator circuitry 5112 generates an example notification for a user (e.g., a pilot, a technician, an operator, etc.) of the fuel distribution system (e.g., the first fuel distribution system 4900, the second fuel distribution system 5000, etc.). For example, the notification generator circuitry 5112 can generate an audio notification (e.g., an alarm, an audio alert, a verbal alert, etc.), a visual notification (e.g., a dash indicator, a graphic, a text warning, etc.), a tactical notification, and/or any other suitable type of notification. For example, if the threshold comparator circuitry 5108 determines that the mass loss rate satisfies the first threshold, the notification generator circuitry 5112 can alert a user of the fuel distribution system that a leak is occurring. For example, when the threshold comparator circuitry 5108 determines that the mass loss rate satisfies the second threshold, the notification generator circuitry 5112 alerts a user of the sensors of the fuel distribution system may need to be recalibrated.
The data storage 5114 can be used to store any information associated the sensor interface circuitry 5102, the mass flow determiner circuitry 5104, the mass loss determiner circuitry 5106, the threshold comparator circuitry 5108, the fuel distribution system interface circuitry 5110, and/or the notification generator circuitry 5112. The example data storage 5114 of the illustrated example of
While an example manner of implementing the fuel distribution controller circuitry 4808 of
The x-axis 5202 measures the independent variable time, which begins at T1, and ends at T2. In some examples, an elapsed time between T1 and T2 is a period over which an average mass loss and/or cumulative mass loss is determined. The x-axis can be measured in any suitable unit (e.g., seconds, minutes, etc.). The y-axis 5204 measures the cumulative mass loss, which ranges from MLmin and MLmax which are selected to ensure the first relationship curve 5206 is visible in the first diagram 5200.
The first relationship curve 5206 represents an instantaneous mass loss at a particular time determined via a mass balancing analysis conducted by the mass loss determiner circuitry 5106 of
The second relationship curve 5212 represents the instantaneous mass loss at a particular period of time determined via a mass balancing analysis conducted by the mass loss determiner circuitry 5106 of
Similar to the example operations of
At block 5304, the mass flow determiner circuitry 5104 determines hydrogen mass flow associated with outlet of the hydrogen fuel tanks. For example, when the first fuel distribution system 4900 is being analyzed, the mass flow determiner circuitry 5104 can determine the mass flow from the GH2 fuel tanks using Equations (1) and (2) and/or the mass flow rate from the LH2 tank 4906 using the equations (3), (4), and (5). In some examples, when the second fuel distribution system 5000 is being analyzed, the mass flow determiner circuitry 5104 can determine the mass flow from the CCH2 tank using equations (6)-(8). In other examples, the mass flow rate determiner can determine the mass flow rate from the hydrogen sources from any suitable means.
At block 5306, the mass flow determiner circuitry 5104 determines the hydrogen mass flow associated with the inlet of the combustor (e.g., the combustor 4910 of
At block 5308, the mass flow determiner circuitry 5104 determines whether the valve vent is open. For example, the mass flow determiner circuitry 5104 can determine whether the valve vent is open based on a user input. In some examples, the mass flow determiner circuitry 5104 can determine whether the valve vent is open based on sensor data received from the sensor interface circuitry 5102 and/or any other suitable method. When the mass flow determiner circuitry 5104 determines the valve vent is open, the operations 5300 advance to block 5310. When the mass flow determiner circuitry 5104 determines the valve vent is not open, the operations 5300 advance to block 5312.
At block 5310, the mass flow determiner circuitry 5104 determines the hydrogen mass flow through the vent valve. For example, the mass flow determiner circuitry 5104 can determine the mass vented from the second GH2 buffer tank 4962 using the properties of the vent valve 4974, the pressure of the second GH2 buffer tank 4962, and the duration of the valve remains open. In some examples, the mass flow determiner circuitry 5104 can determine the mass flow through the vent using equation (9). In other examples, the mass flow determiner circuitry 5104 can determine the hydrogen mass flow by any other suitable method.
At block 5312, the mass loss determiner circuitry 5106 determines the average mass loss of hydrogen over a period of time. For example, the mass loss determiner circuitry 5106 can compare the mass inflows (e.g., from the LH2 tank 4906, from the GH2 tank bank 4905, from the CCH2 tank 5002, etc.) and mass outflows (e.g., into the combustor 4910, vented from the second GH2 buffer tank 4962, etc.). For example, the mass loss determiner circuitry 5106 can determine the average mass loss of hydrogen of the first fuel distribution system 4900 using equations (10) and (11) and the second fuel distribution system 5000 using equations (12) and (13). In other examples, the mass loss determiner circuitry 5106 can determine the average mass loss by any other suitable means.
At block 5314, the threshold comparator circuitry 5108 determines whether the average mass loss satisfies a first threshold. For example, the threshold comparator circuitry 5108 can determine whether the average mass loss exceeds the first threshold (e.g., a recalibration threshold, etc.). When the threshold comparator circuitry 5108 determines the mass loss satisfies the first threshold, the operations 5300 advance to block 5318. When the threshold comparator circuitry 5108 determines the mass loss does not satisfy the first threshold, the operations 5300 advance to block 5320.
At block 5316, the notification generator circuitry 5112 issues a notification to recalibrate sensors (e.g., the sensors 4912, 4914, 4928, 4960, 4967, 4968 of
At block 5318, the threshold comparator circuitry 5108 determines whether the average mass loss satisfies a second threshold. For example, the threshold comparator circuitry 5108 can compare the determined mass loss to a second threshold (e.g., a leak notification threshold, etc.) When the threshold comparator circuitry 5108 determines the mass loss satisfies the second threshold, the operations 5300 advance to block 5320. When the threshold comparator circuitry 5108 determines the mass loss does not satisfy the first threshold, the operations 5300 ends.
At block 5320, the notification generator circuitry 5112 issues a notification that a hydrogen leak is present in the fuel distribution system. For example, the notification generator circuitry 5112 can generate an audio notification (e.g., an alarm, an audio alert, a verbal alert, etc.), a visual notification (e.g., a dash indicator, a graphic, a text warning, etc.), a tactical notification, and/or any other suitable type of notification.
At block 5322, the fuel distribution system interface circuitry 5110 identifies portions of the fuel distribution system including the leak. For example, when the threshold comparator circuitry 5108 determines the mass loss rate satisfies the first threshold, the fuel distribution system interface circuitry 5110 can, via the sensor data, determine where in the fuel distribution system (e.g., the first fuel distribution system 4900 and/or the second fuel distribution system 5000, etc.) the leak has occurred. For example, the location of the leak can be inferred by controlling the valve 4940 of
At block 5324, the fuel distribution system interface circuitry 5110 isolates the portion of the fuel distribution system including the leak. For example, the fuel distribution system interface circuitry 5110 can isolate the detected leak by closing a valve, closing a regulator, disabling the combustor 4910, routing hydrogen through an alternative part of the fuel distribution system, etc. In some examples, if a leak is detected in a portion of the fuel distribution system 4900 that has an alternative path (e.g., back-up path, a redundant path, etc.) available, the fuel distribution system interface circuitry 5110 can close the portion with the leak (e.g., via a valve, etc.) and the hydrogen fuel can be rout through the alternative. In some examples, if a leak is detected in one of the hydrogen delivery assemblies 4902, 4904, the fuel distribution system interface circuitry 5110 can disable said delivery system (e.g., by closing a corresponding one of the inputs 4942, 4944, etc.) until the first fuel distribution system 4900 can be serviced/repaired. The operations 5300 end.
Example methods and apparatus described above enable the integrated tank systems(s) 500-900 disclosed herein to be safely implemented in fuel distribution systems (e.g., a LH2 fuel distribution system, a GH2 fuel distribution system, a CCH2 fuel distribution system, etc.) of a gas turbine engine. Examples described above include a system that continuously monitors the health of the integrated cryogenic hydrogen tank system(s) 500-900 and the fuel distribution system(s) of a gas turbine engine associated with an aircraft. Examples described above compare the flow of hydrogen from the from the integrated tank system(s) 500-900 against the flow of hydrogen entering a combustor of the engine to determine whether fuel loss exists in the integrated tank system(s) 500-900 and/or a fuel distribution system.
Example systems, apparatus, and methods described below enable the integrated tank systems(s) 500-900 of
The fuel system 5500 of
The fuel system 5500 further includes one or more gaseous hydrogen (GH2) fuel tanks 5508 configured to store a second portion of hydrogen fuel in a gaseous phase. The GH2 fuel tanks 5508 store the second portion of hydrogen fuel at an increased pressure (relative to the LH2 fuel tanks 5506), which reduces a size or quantity of the one or more GH2 fuel tanks 5508 within the aircraft. For example, the GH2 fuel tanks 5508 store the second portion of hydrogen fuel at a pressure of at least about 100 bar, such as at least about 200 bar, such as at least about 400 bar, such as at least about 600 bar, such as at least about 700 bar, and up to about 1,000 bar. In some examples, the GH2 fuel tanks 5508 store the second portion of the hydrogen fuel at a temperature within about 50° C. of an ambient temperature, or between about −50° C. and about 100° C. Although multiple GH2 fuel tanks 5508 are illustrated in
In some examples, a substantial portion of the total hydrogen fuel storage capacity of the fuel system 5500 is provided by the LH2 fuel tanks 5506. In some examples, the LH2 fuel is provided by one or more of the integrated tank systems 500-900 of
The fuel system 5500 further includes a fuel delivery assembly 5510 to transmit hydrogen fuel to the engine 5502. The fuel delivery assembly 5510 includes a LH2 delivery assembly 5512 fluidly coupled to the LH2 fuel tanks 5506, a GH2 delivery assembly 5514 fluidly coupled to the GH2 fuel tank 5508, and a regulator assembly 5516 fluidly coupled to both the LH2 delivery assembly 5512 and the GH2 delivery assembly 5514 for providing hydrogen fuel to the engine 5502.
The LH2 delivery assembly 5512 includes a pump 5518 and a heat exchanger 5520 located downstream of the pump 5518. The pump 5518 cryogenically pressurizes the LH2 fuel such that the first portion of hydrogen fuel flows from the LH2 fuel tanks 5506 through the LH2 delivery assembly 212. Operation of the pump 5518 can compress the first portion of hydrogen fuel in the LH2 delivery assembly 5512 before the hydrogen fuel flows into the regulator assembly 5516 and engine 5502. In some examples, the pump 5518 cryogenically compresses the LH2 fuel into a supercritical state, otherwise referred to as cryo-compressed hydrogen (CCH2). In some examples, the pump 5518 can be another type of cryogenic pump configured to provide a flow of LH2 fuel. In some examples, the pump 5518 is implemented as the LH2 pump 2504 included in the first and/or second phase separating LH2 pumping systems 2700, 2800 described above in connection with
In the illustrated example of
In some examples, given the difficulty of pumping LH2 at relatively low temperatures to maintain its liquid phase, the pump 5518 is not capable of operating across a wide range of capacities. For example, the pump 5518 may have a maximum pump capacity and a minimum pump capacity (each in kilograms per second). A ratio of the maximum pump capacity to the minimum pump capacity is referred to herein as a “turndown ratio” of the pump 5518. In some examples, the pump 5518 has a turndown ratio of at least 1:1 and up to about 6:1. For example, the pump 5518 has a turndown ratio of at least about 2:1, such as at least about 3:1, and up to about 5:1. The effect of such a configuration on the fuel system 5500 will be described in greater detail below.
The heat exchanger 5520 is included in the fuel system 5500 to convert the LH2 in the LH2 delivery assembly 5512 from the liquid phase to a gaseous phase. In some examples, the heat exchanger 5520 is coupled to the engine 5502 such that heat transfers from an accessory system of the engine 5502 to the LH2. The heat exchanger 5520 enables an amount of heat to transfer to the LH2 that is sufficient enough to convert the LH2 to the gaseous phase.
As mentioned previously, LH2 tanks (e.g., the fuel tanks 5506, the integrated tank system(s) 500-900, etc.) contain LH2 substantially completely in the liquid phase. However, a portion of the volume of the fuel tanks 5506 contains hydrogen vapor due to boil-off the LH2. Thus, the fuel system 5500 includes a boil-off assembly 5540 to prevent a vapor pressure within the fuel tanks 5506 from exceeding a pressure threshold. The example boil-off assembly 5540 allows the hydrogen vapor to purge from the LH2 fuel tanks 5506. More specifically, the boil-off fuel assembly 5540 allows excess GH2 in the LH2 fuel tanks 5506 to be used as GH2 fuel for the engine 5502.
The boil-off fuel assembly 5540 includes a boil-off compressor 5542 and a boil-off tank 5544. The boil-off compressor 5542 is fluidly coupled to the LH2 fuel tanks 5506, and the boil-off tank 5544 is fluidly coupled to the boil-off compressor 5542. The boil-off tank 5544 is further coupled to the GH2 delivery assembly 5514. During operation, the boil-off fuel assembly 5540 receives GH2 from the LH2 fuel tanks 5506, the boil-off compressor 5542 compresses the GH2, and the boil-off tank 5544 provides pressurized GH2 fuel to other systems and/or assemblies (e.g., the GH2 delivery assembly 5514).
In some examples, the boil-off tank 5544 stores the GH2 fuel at a lower pressure than that of the GH2 fuel tank 5508. For example, the boil-off tank 5544 holds GH2 fuel at a pressure of between about 100 bar and about 400 bar, such as between 130 bar and about 300 bar. In some examples, a volume of the boil-off tank 5544 is smaller than a volume of the GH2 fuel tanks 5508 due to the smaller pressures. The boil-off compressor 5542 may substantially completely pressurize the GH2 fuel in the boil-off tank 5544. Thus, the boil-off compressor 5542 can increase or maintain the pressure of the GH2 fuel in the boil-off tank 5544 based on a back vapor pressure in the LH2 fuel tanks 5506. Furthermore, the size of the boil-off compressor 5542 can be relatively smaller than the pump 5518 due to the smaller output pressure requirements.
The GH2 delivery assembly 5514 of
In the illustrated example of
In the illustrated example, the regulator assembly 5516 is fluidly coupled to both the LH2 delivery assembly 5512 and the GH2 delivery assembly 5514 for providing GH2 fuel to the engine 5502, and more specifically, to the combustor 5504 of the engine 5502.
In the illustrated example of
In the illustrated example, the regulator assembly 5516 further includes a regulator assembly flow regulator 5570 (“RA flow regulator 5570”). The RA flow regulator 5570 may be configured as an actively controlled variable throughput valve configured to provide a variable throughput ranging from 0% (e.g., a completely closed off position) to 100% (e.g., a completely open position), as well as a number of intermediate throughput values therebetween. More specifically, the RA flow regulator 5570 includes a valve portion 5574 and an actuator 5576. The actuator 5576 is mechanically coupled to the valve portion 5574 to provide the variable throughput therethrough.
Furthermore, the fuel system 5500 includes a buffer tank 5578 to receive GH2 fuel upstream of the RA flow regulator 5570. The buffer tank 5578 can collect GH2 and reduce a pressure input to the RA flow regulator 5570 such that excessive damage or wear does not occur. In some examples, the buffer tank 5578 includes a pressure sensor to measure the pressure in the buffer tank 5578 and/or a flowmeter to measure the flowrate exiting the buffer tank 5578. The buffer tank 5578 may also include a regulator valve to automatically adjust the output flowrate based on the measured pressures and/or flowrates and target pressures and/or flowrates.
Referring now to
Typically, the engine 5502 includes accessory systems to improve certain operating mechanisms. In the illustrated example, the engine 5502 includes a lubrication system 5632 to provide, maintain, and recycle a lubricant used to reduce wear between rotating components in contact and/or in close proximity to each other. The lubrication system 5632 includes a recirculation assembly 5634 to receive a lubricant (e.g., oil, etc.) from a relatively hot section of the engine 5502 (e.g., the HP turbine 5626, the HP compressor 5624, etc.), cool the lubricant, and provide the lubricant back to the engine 5502 at a lower temperature. In some examples, the recirculation assembly 5634 recycles the lubricant back to the same section of the engine 5502, such as the HP turbine 5626, the HP compressor 5624, etc. In some examples, the recirculation assembly 5634 provides the lubricant to a different section of the engine 5502, such as the LP turbine 5628, the LP compressor 5622, etc. It should be appreciated, that that the lubrication system 5632 is an example accessory system illustrated in
In the illustrated example of
However, it should be appreciated, that the fuel system 5500 may selectively use the second heat exchanger 5635B based on operating conditions of the engine 5502. In other words, during certain stages of operation, the additional heat may be needed to sufficiently vaporize the LH2 fuel. For example, during high thrust operations, the LH2 fuel flows at high rates, which inhibits a heat transfer rate in the first heat exchanger 5635A. Additionally, during startup operations, the lubrication oil is relatively cool, which requires a larger amount of heat transfer than is possible with the first heat exchanger 5635A alone. In some examples, the second heat exchanger 5635B is coupled to the exhaust section 5630 of the engine 5502 to transfer waste heat from exhaust gases to the LH2 fuel in the LH2 delivery assembly 5512 and downstream of the first heat exchanger 5635A.
The fuel system 5500 of the illustrated example of
In some examples, the heat exchanger 5520 and a portion of the LH2 delivery assembly 5512 are positioned within an outer casing of the engine 5502. In some examples, the heat exchanger 5520 and the LH2 delivery assembly 5512 are positioned outside of the casing and proximate to the engine 5502. As such, the heat exchanger 5520 of the LH2 delivery assembly 5512 may be located remotely from the engine 5502 (e.g., on the wing of the aircraft), and an intermediate thermal transport bus may transport heat from the engine 5502 to the heat exchanger 5520 via a heat transfer fluid.
The fuel system 5500 of
The fuel system 5500 of
In the illustrated example of
In some examples, the fuel system 5500 includes a phase separating LH2 pumping system (e.g., the first phase separating LH2 pumping system 2700 of
The hydrogen fuel system 5500 of
The fuel system 5500 of
The fuel system 5500 of
The fuel system 5500 of
As illustrated in
The ventilation device 5810 also includes one or more louvers 5820 to selectively allow or restrict flow through the opening 5814. The louvers 5820 are positioned within the opening 5814 and rotatably coupled to the wall 5812. Thus, the louvers 5820 can be moved between a fully closed position and fully opened position. In some examples, the louvers 5820 are in either the fully closed position or the fully opened position. In other examples, the louvers 5820 are adjustable to various positions between the fully closed position and the fully opened position. Although, two louvers 5820 are illustrated in
The quick release panel 5910 of
As shown in the illustrated example, the first, second, and third compartments 6004-6008 are positioned at various locations within a fuselage 6012 of the aircraft 6002. The quick release panels 6010 are coupled to each one of the first, second, and third compartments 6004-6008. In some examples, the quick release panels 6010 are disposed on the fuselage 6012 and connected to the first, second, and third compartments 6004-6008. In other examples, the quick release panels 6010 are located within the fuselage 6012. In some examples, the quick release panels 6010 are disposed on the first, second, and third compartments 6004-6008. In some examples, one or more of the first, second, and/or third compartments 6004-6008 and the associated quick release panels 6010 are located on and/or within a wing 6014 of the aircraft 6002. In some examples, a different number of compartments (e.g., one, three, five, etc.) are included in the fuselage 6012. In some examples, the first, second, and/or third compartment(s) 6004-6008 are implemented as the fourth compartment 5716 of
As illustrated in
In some examples, the quick release panel 6208 is a first quick release panel and the pivot joint 6226 is a first pivot joint. In such examples, the engine 6202 includes a plurality of quick release panels that are coupled to a plurality of pivot joints and are distributed circumferentially about the core 6206. The plurality of quick release panels may actuate substantially simultaneously to release hydrogen from multiple areas of the core 6206 and/or the combustor 6212. Alternatively, the second casing portion 6224 may be encase the combustor 6212 and include the quick release panel 6208. In some examples, the quick release panel 6208 has another functionality as described herein, such as a frangible portion that is punctured or opened.
As shown in
The system 6300 includes a computing system 6302 communicatively coupled to one or more components of the aircraft 100, the engine 5502, and/or the hydrogen fuel system 5500 to allow the components therein to be electronically or automatically controlled. In the illustrated example, the computing system 6302 is communicatively coupled to the hydrogen sensors 5736 via communicative link(s) 6304. As such, the computing system 6302 obtains data from the hydrogen sensors 5736 indicating the level of hydrogen present within the compartments 5710-5718. In some examples, the hydrogen sensors 5736 measure the concentration of hydrogen molecules present within a portion of the air in the compartment (e.g., the first compartment 5710). In some examples, the computing system 6302 determines the level of hydrogen present in the compartment based on a concentration measurement obtained from the hydrogen sensors 5736. In some examples, the computing system 6302 determines a rate of change of the level of hydrogen present within the compartment (e.g., the first compartment 5710) based on concentration measurements obtained over time from the hydrogen sensors 5736.
Furthermore, the computing system 6302 is communicatively coupled to the control valves 5722-5728, the ventilation devices 5730, the vent valves 5732, and the quick release panel actuators 5920 via the communicative link(s) 6304. Thus, the computing system 6302 is configured to control operation of the control valves 5722-5728, the ventilation devices 5730, the vent valves 5732, and the quick release panel actuators 5920 based on measurement data from the hydrogen sensors 5736 to reduce the hydrogen concentration within the compartment(s) 5710-5718. In some examples, the computing system 6302 is communicatively coupled to another component of the aircraft 100, the turbofan engine 5502, and/or the hydrogen fuel system 5500.
The computing system 6302 includes one or more processor(s) 6306 and associated memory device(s) 6308 configured to perform a variety of computer-implemented functions. The processor(s) 6306 may be implemented as an example processor platform. For example, the processor(s) 6306 can be the same as, integrated with, and/or connected to the processor platforms 1200, 2400, 3400, and/or 5400 illustrated in
The various functions of the computing system 6302 may be performed by a single processor-based device or may be distributed across any number of processor-based devices, in which instance such devices may be considered to form part of the computing system 6302. For instance, the functions of the computing system 6302 may be distributed across multiple application-specific controllers or computing devices, such as a hydrogen fuel system controller, an engine controller, such as a FADEC, and/or other subsystem controllers.
Referring now to
For purposes of clarity, the control logic 6400 is described below in connection with the first compartment 5710 of the fuel system 5500. It should be appreciated that the control logic 6400 can simultaneously be implemented with another compartment of the fuel system 5500, such as the second, third, fourth, and/or fifth compartments 5712-5718. Thus, the control logic 6400 can be executed to detect hydrogen leaks and simultaneously initiate the appropriate control actions in all of the compartments of the fuel system 5500 to dilute the hydrogen leaks.
At block 6402, the computing system 6302 receives hydrogen concentration data from the hydrogen sensors 5736 indicating the level of hydrogen present within compartment(s) of a vehicle. Specifically, the computing system 6302 obtains hydrogen level data from the hydrogen sensors 5736 via the communicative link(s) 6304 indicating the level of hydrogen present within the first compartments 5710.
At block 6404, the computing system 6302 analyzes or otherwise processes the hydrogen sensor data to determine the level of hydrogen present within the first compartment 5710. For example, the processor(s) 6306 can calculate the parts per million of hydrogen compounds and/or atoms in the air based on the hydrogen sensor data, the volume of the first compartment 5710, and/or a rate of increase of hydrogen levels.
At block 6406, the computing system 6302 determines whether the level of hydrogen present within the compartment satisfies a first threshold value (e.g., a hydrogen concentration threshold, etc.). For example, the computing system 6302 compares the level of hydrogen present within the first compartment 5710 determines whether the level is greater than the first threshold value. When computing system 6302 determines that the hydrogen levels do exceed the first threshold value, the control logic 6400 proceeds to block 6418. When the computing system 6302 determines that the hydrogen levels do not exceed the first threshold value, the control logic 6400 proceeds to block 6408.
At block 6408, the computing system 6302 determines the rate of change of the level of hydrogen present within the compartment based on the received hydrogen sensor data. For example, the computing system 6302 analyzes or otherwise processes hydrogen sensor data obtained over time to determine the rate of change of the hydrogen levels within the first compartment 5710.
At block 6410, the computing system 6302 compares the determined rate of change of the level of hydrogen present within the compartment to a second threshold value (e.g., a rate of change threshold, etc.). For example, the computing system 6302 compares the rate of change of hydrogen levels within the first compartment 5710 to the second threshold value. When the computing system 6302 determines that the rate of change of hydrogen levels within the first compartment 5710 does exceeds the second threshold value, the control logic 6400 proceeds to block 6412. Conversely, when the computing system 6302 determines that the rate of change of hydrogen levels within the first compartment 5710 does not exceed the second threshold value, the control logic 6400 returns to block 6402.
At block 6412, the computing system 6302 determines whether the ventilation for the compartment is at the maximum ventilation value. For example, the computing system 6302 analyzes the operation of the ventilation device 5730 associated with the first compartment 5710 to determine whether the ventilation device 5730 is operating at a maximum level (e.g., the fan 5822 is operating at a maximum speed). When the computing system 6302 determines that the ventilation device 5730 of the first compartment 5710 is not operating at the maximum level, the control logic 6400 proceeds to block 6414. Conversely, when the computing system 6302 determines that the ventilation device 5730 of the first compartment 5710 is operating at the maximum level, the control logic 6400 proceeds to block 6416.
At block 6414, the computing system 6302 increases the ventilation provided to the compartment. For example, the computing system 6302 is causes the louvers 5820 of the ventilation device 5810 of
At block 6416, the computing system 6302 activates the quick release panel associated with the compartment. For example, the computing system 6302 sends a control signal to the quick release panel actuator 5920 such that the quick release panel 5734 associated with the first compartment 5710 opens. Causing the quick release panel 5734 to open rapidly provides a large quantity of air to the first compartment 5710 and/or discharges leaked hydrogen from the first compartment 5710.
At block 6418, the computing system 6302 determines whether the ventilation for the compartment is at the maximum ventilation value. For example, the computing system 6302 can perform the same or substantially the same operations as those associated with block 6412. When the computing system 6302 determines that the first compartment 5710 is not venting hydrogen sufficiently, the control logic 6400 proceeds to block 6420. Conversely, when the computing system 6302 determines that the first compartment 5710 is venting hydrogen sufficiently, the control logic 6400 proceeds to 6422.
At block 6420, the computing system 6302 increases the ventilation provided to the compartment. For example, the computing system 6302 can perform the same or substantially the same operations as those associated with block 6414. Following completion of block 6420, the control logic 6400 returns to block 6402.
At block 6422, the computing system 6302 determines the rate of change of the hydrogen levels within the compartment based on the received hydrogen sensor data. For example, the computing system 6302 can perform the same or substantially the same operations as those associated with block 6408.
At block 6424, the computing system 6302 determines whether the rate of change of the hydrogen levels within the compartment satisfy the second threshold value. For example, the computing system 6302 can perform the same or substantially the same operations as those associated with block 6410. When the rate of change of hydrogen levels within the first compartment 5710 does exceed the second threshold, the control logic 6400 proceeds to block 6430 of
At block 6426, the computing system 6302 determines whether the compartment is isolated. For example, the computing system 6302 determines whether the first control valve 5722 of the first compartment 5710 is in the closed position. When the computing system 6302 determines that the first compartment 5710 is isolated, the control logic 6400 proceeds to block 6430 of
At block 6428, the computing system 6302 isolates the compartment. For example, the computing system 6302 causes the first control valve 5722 to close and prevent the flow of hydrogen from the first LH2 fuel tank 5506A and the first compartment 5710. The computing system 6302 can also close the ventilation device 5730 to further isolate the first compartment 5710. In some examples, the computing system 6302 causes the second control valve 5724 to open and allow the flow of hydrogen from the second LH2 fuel tank 5506B, which maintains operation of the engine 5502 after the first compartment 5710 is isolated. Following completion of block 6428, the control logic 6400 returns to block 6402.
As shown in
At block 6432, the computing system 6302 opens the vent valve associated with the compartment. For example, the computing system 6302 sends a control signal to the vent valve 5732 associated with the first compartment 5710 that causes the vent valve 5732 to open. Such opening of the vent valve 5732 reduces the pressure in the first compartment 5710, which reduces the magnitude of the leak therein. Following completion of block 6432, the control logic 6400 returns to block 6402.
At block 6434, the computing system activates the quick release panel associated with the compartment. For example, the computing system 6302 performs operations that are the same and/or similar to those associate with block 6416 of
At block 6602, the method 6600 includes receiving, with a computing system, hydrogen sensor data indicative of a level of hydrogen present within the compartment. For example, as described above, the computing system 6302 may receive hydrogen sensor data from the hydrogen sensors 5736. The received data is, in turn, indicative of the level of hydrogen present within the compartments 5710-5718 in which components of the hydrogen fuel system 5500 are present.
At block 6604, the method 6600 includes determining, with the computing system, at least one of the level of hydrogen present within the compartment or a rate of change of the level of hydrogen present within the compartment based on the data generated by the hydrogen sensor. For example, as described above, the computing system 6302 determines the level of hydrogen present within the compartments 5710-5718 and/or the rate of change of the level of hydrogen present within the compartments 5710-5718 based on the received hydrogen sensor data.
At block 6606, the method 6600 includes comparing, with the computing system, the determined at least one of the level of hydrogen present within the compartment or the rate of change of the level of hydrogen present within the compartment to an associated threshold value. For example, as described above, the computing system 6302 compares the determined level of hydrogen present within the compartments 5710-5718 and/or the rate of change of the level of hydrogen present within the compartments 5710-5718 to an associated threshold value(s).
At block 6608, the method 6600 includes initiating, with the computing system, a control action associated with reducing the level of hydrogen present within the compartment when the determined at least one of the level of hydrogen present within the compartment or the rate of change of the level of hydrogen present within the compartment exceeds the associated threshold value. For example, as described above, when the determined the level of hydrogen present within the compartments 5710-5718 and/or the rate of change of the level of hydrogen present within the compartments 5710-5718 exceeds the associated threshold value(s), the computing system 6302 initiates one or more control actions associated with reducing the level of hydrogen present within the compartments 5710-5718. From the foregoing, it should be appreciated that example integrated cryogenic hydrogen tank systems (“integrated tank systems”) are disclosed herein that enable multiple cryogenic tanks to operate as a single vessel on a hydrogen aircraft. Example integrated tank systems disclosed herein can include example LH2 refueling systems to refuel the LH2 tanks of the example integrated tank systems substantially simultaneously via one refueling line. Furthermore, example integrated tank systems disclosed herein can include example phase separating LH2 pump systems to extract LH2 from the LH2 tanks of the example integrated tank systems substantially simultaneously via one extraction line. In some examples, the example integrated tank systems disclosed herein can include extraction lines to transmit LH2 and/or GH2 to hydrogen fuel cell power systems for electronically powering various onboard systems. Example integrated cryogenic hydrogen tank systems disclosed herein can further include monitoring systems to detect the health and safety of cryogenic hydrogen tanks, flowlines, fuel supply systems, and/or fuel consumption systems associated with disclosed examples. In some examples, the example integrated tank systems disclosed herein can include example fuel systems for detecting and diluting hydrogen leaks that may occur from the example integrated tank systems. As such, it should be appreciated that other example systems, apparatus, and methods are disclosed herein that improve the functionality and efficiency of the example integrated cryogenic hydrogen tank systems disclosed herein.
Example methods, apparatus, systems, and articles of manufacture to integrate multiple cryogenic hydrogen tanks into a single vessel are disclosed herein. Further aspects of the disclosure are provided by the subject matter of the following clauses:
A system to integrate multiple cryogenic tanks on an aircraft, the system comprising a first cryogenic tank coupled to a second cryogenic tank via a liquid hydrogen (LH2) transfer flowline and a gaseous hydrogen (GH2) transfer flowline, the LH2 transfer flowline and the GH2 transfer flowline to maintain a fuel level and a vapor pressure across the system, the fuel level corresponding to a cryogenic liquid, an inlet port connected to one of the first cryogenic tank or the second cryogenic tank, an LH2 extraction flowline connected to at least one of the first or second cryogenic tanks to supply the cryogenic liquid to a fuel management system, and a pressure safety system coupled to at least one of the first or second cryogenic tanks via a GH2 extraction flowline.
The system of any preceding clause, wherein the LH2 transfer flowline, the GH2 transfer flowline, and the LH2 extraction flowline are vacuum jacketed flowlines.
The system of any preceding clause, wherein the pressure safety system includes a pressure safety valve and a burst disc, the pressure safety valve to release the vapor pressure in the first and second cryogenic tanks when the vapor pressure satisfies a safety threshold, the burst disc to rupture when the pressure safety valve malfunctions.
The system of any preceding clause, further including a thermosiphon loop integrated into one of the first or second cryogenic tanks to regulate the vapor pressure of the system.
The system of any preceding clause, further including a heating system in one of the first or second cryogenic tanks to regulate the vapor pressure of the system.
The system of any preceding clause, wherein the cryogenic liquid is liquid hydrogen, further including a first isolation valve in the LH2 transfer flowline to enable or inhibit flow of the liquid hydrogen between the first and second cryogenic hydrogen tanks, and a second isolation valve in the GH2 transfer flowline to enable or inhibit flow of hydrogen vapor between the first and second cryogenic hydrogen tanks.
The system of any preceding clause, wherein the first cryogenic tank is included in a first group of cryogenic tanks, and the second cryogenic tank is included in a second group of cryogenic tanks, further including a first set of LH2 transfer flowlines and GH2 transfer flowlines to couple the first group of cryogenic tanks in series, a second set of LH2 transfer flowlines and GH2 transfer flowlines to couple the second group of cryogenic tanks in series, a third set of LH2 transfer flowlines and GH2 transfer flowlines to couple the first and second groups of cryogenic tanks in parallel, and a plurality of isolation valves in the first set, the second set, and the third set of LH2 transfer flowlines and GH2 transfer flowlines to enable or inhibit flow between the first and second groups of tanks.
The system of any preceding clause, wherein the pressure safety system is a first pressure safety system coupled to the first group of cryogenic tanks via a plurality of first GH2 extraction flowlines, further including a second pressure safety system coupled to the second group of cryogenic tanks via a plurality of second GH2 extraction flowlines.
The system of any preceding clause, wherein the first group of cryogenic tanks includes two or more cryogenic tanks, and the second group of cryogenic tanks includes two or more cryogenic tanks.
The system of any preceding clause, further including a first pump in the first group of cryogenic tanks and a second pump in the second group of cryogenic tanks, the first and second pumps to trim liquid hydrogen between one or more cryogenic tanks of the system.
The system of any preceding clause, wherein the LH2 extraction flowline is a first LH2 extraction flowline connected to the first cryogenic tank, further including a second LH2 extraction flowline connected to the second cryogenic tank.
The system of any preceding clause, wherein the fuel management system supplies liquid hydrogen from at least one of the first cryogenic tank or the second cryogenic tank to a fuel cell power system.
The system any preceding clause, wherein the fuel cell power system converts liquid hydrogen to gaseous hydrogen, the fuel cell power system to utilize the gaseous hydrogen to generate power.
The system of any preceding clause, wherein the fuel cell power system supplies electrical power to a propulsor of a gas turbine engine.
The system of any preceding clause, wherein the fuel management system includes a liquid hydrogen pump and a phase separator to remove hydrogen vapor from liquid hydrogen extracted from the system.
An apparatus for integrating multiple cryogenic tanks on an aircraft, the apparatus comprising a first cryogenic tank coupled to a second cryogenic tank via a liquid hydrogen (LH2) transfer flowline and a gaseous hydrogen (GH2) transfer flowline, wherein the LH2 transfer flowline includes a first isolation valve, and the GH2 transfer flowline includes a second isolation valve, a pressure safety system coupled to at least one of the first or second cryogenic tanks via a GH2 extraction flowline, and a controlling device including processor circuitry to execute machine-readable instructions to at least monitor a first vapor pressure in the first cryogenic tank and a second vapor pressure in the second cryogenic tank, determine whether the first or second vapor pressure satisfies a threshold, and in response to determining that the first or second vapor pressure does not satisfy the threshold, close the first and second isolation valves.
The apparatus of any preceding clause, wherein the pressure safety system includes a pressure safety valve and a burst disc, the pressure safety valve to release the vapor pressure in the first and second cryogenic tanks when the vapor pressure satisfies the threshold, the burst disc to rupture when the pressure safety valve malfunctions.
The apparatus of any preceding clause, further including at least one of a thermosiphon loop integrated into one of the first or second cryogenic tanks to regulate the first and second vapor pressures, or a heating system in one of the first or second cryogenic tanks to regulate the first and second vapor pressures.
The apparatus of any preceding clause, wherein the threshold is a first threshold, and the controlling device is further configured to determine whether the first or second vapor pressure satisfies a second threshold, and in response to determining that the first or second vapor pressure does not satisfy the second threshold, activate at least one of the thermosiphon loop or the heating system.
The apparatus of any preceding clause, wherein the first cryogenic tank is included in a first group of cryogenic tanks, and the second cryogenic tank is included in a second group of cryogenic tanks, further including a first set of LH2 transfer flowlines and GH2 transfer flowlines to couple the first group of cryogenic tanks in series, a second set of LH2 transfer flowlines and GH2 transfer flowlines to couple the second group of cryogenic tanks in series, a third set of LH2 transfer flowlines and GH2 transfer flowlines to couple the first and second groups of cryogenic tanks in parallel, and a plurality of isolation valves in the first set, the second set, and the third set of LH2 transfer flowlines and GH2 transfer flowlines to enable or inhibit flow between the first and second groups of tanks.
The apparatus of any preceding clause, wherein the pressure safety system is a first pressure safety system coupled to the first group of cryogenic tanks via a plurality of first GH2 extraction lines, further including a second pressure safety system coupled to the second group of cryogenic tanks via a plurality of second GH2 extraction lines.
The apparatus of any preceding clause, wherein the controlling device is further configured to close the plurality of isolation valves in the third set of LH2 transfer flowlines and GH2 transfer flowlines in response to determining that the first or second vapor pressure does not satisfy the threshold.
A method comprising opening a first isolation valve coupled to a liquid hydrogen (LH2) transfer flowline and a second isolation valve coupled to a gaseous hydrogen (GH2) transfer flowline, the LH2 and GH2 transfer flowlines interconnected between a first tank and a second tank, detecting a first vapor pressure of the first tank and a second vapor pressure of the second tank, determining whether the first and second vapor pressures satisfy a threshold, and closing the first and second isolation valves when the first vapor pressure or the second vapor pressure does not satisfy the threshold.
The method of any preceding clause, wherein the threshold is a first threshold, further including determining whether the first or second vapor pressures satisfies a second threshold, and at least one of opening an automatic valve of a thermosiphon loop when the first or second vapor pressures does not satisfy the second threshold, the thermosiphon loop to increase a vapor pressure in the first and second tanks, or activating a heating system in the first or second tanks when the first or second vapor pressures does not satisfy the second threshold, the heating system to increase a vapor pressure in the first and second tanks.
The method of any preceding clause, wherein the first tank is included in a first group of tanks connected in series, the second tank is included in a second group of tanks connected in series, the first and second groups of tanks connected in parallel.
The method of any preceding clause, wherein the first and second isolation valves are included in a first set of isolation valves interposed between tanks of the first group of tanks, further including a second set of isolation valves interposed between tanks of the second group of tanks, and a third set of isolation valves interposed between the first and second groups of tanks.
The method of any preceding clause, wherein the first vapor pressure corresponds to the first group of tanks, the second vapor pressure corresponds to the second group of tanks, and the closing of the first and second isolation valves further includes closing the first set of isolation valves and the third set of isolation valves when the first vapor pressure does not satisfy the threshold, and closing the second set of isolation valves and the third set of isolation valves when the second vapor pressure does not satisfy the threshold.
An aircraft comprising a fuselage having a centerline extending axially between a nose and a tail, a gas turbine engine configured to provide power to the aircraft, an integrated cryogenic hydrogen tank system to store liquid hydrogen (LH2) fuel, the integrated cryogenic hydrogen tank system including at least two tanks fluidly coupled together via a LH2 transfer flowline and a gaseous hydrogen (GH2) transfer flowline, each tank of the integrated cryogenic hydrogen tank system having (i) an internal chamber for holding the LH2 fuel and (ii) a LH2 extraction flowline fluidly coupled to the internal chamber, the LH2 extraction flowline extending from a first tank of the integrated cryogenic hydrogen tank system in a first direction, the first direction oriented toward the nose and at a downward angle relative to the centerline of the fuselage, and a fuel delivery assembly fluidly coupled to the LH2 extraction flowline and fluidly connecting the integrated cryogenic hydrogen tank system to the gas turbine engine, the fuel delivery assembly having a LH2 pump system to provide the LH2 fuel from the integrated cryogenic hydrogen tank system to the gas turbine engine.
The aircraft of any preceding clause, wherein each tank of the integrated cryogenic hydrogen tank system includes at least one baffle in the internal chamber.
The aircraft of any preceding clause, wherein the downward angle is greater than twenty degrees.
The aircraft of any preceding clause, wherein the LH2 extraction flowline is a vacuum jacketed flowline.
The aircraft of any preceding clause, wherein the LH2 pumping system is a phase separating LH2 pumping system including a phase separator having a filtration structure and a vapor accumulator, a hydrogen vapor return flowline fluidly coupled to the vapor accumulator and the internal chamber of the first tank, and a LH2 pump fluidly coupled to the phase separator via a LH2 flowline and fluidly coupled to the hydrogen vapor return flowline.
The aircraft of any preceding clause, wherein the LH2 extraction flowline is fluidly coupled to the internal chamber of the first tank and filtration structure of the phase separator, wherein hydrogen vapor return flowline includes a first portion and a second portion, wherein the vapor accumulator is fluidly coupled to the internal chamber of the first tank via the first portion, and wherein the LH2 pump is fluidly coupled to the first portion via the second portion.
The aircraft of any preceding clause, wherein the first tank is fluidly coupled to a second tank of the integrated cryogenic hydrogen tank system, and wherein the fuselage includes a maximum internal diameter, the first and second tanks are cylindrical having an outer diameter, and a ratio of the outer diameter to the maximum internal diameter is between eight-tenths and nine-tenths.
The aircraft of any preceding clause, further including a pair of wings connected to the fuselage and configured to generate a wing center of lift, the first tank having a first center of gravity positioned forward of the wing center of lift, the second tank having a second center of gravity aligned with the wing center of lift, wherein the integrated cryogenic hydrogen tank system defines a third center of gravity positioned aft of the wing center of lift, and wherein a position of the third center of gravity is based on a combination of the first center of gravity and the second center of gravity.
The aircraft of any preceding clause, wherein the first tank is positioned forward of the wing center of lift, and the second tank is positioned aft of the wing center of lift.
The aircraft of any preceding clause, wherein the first tank is fluidly coupled to a first group of tanks, and wherein the integrated cryogenic hydrogen tank system includes a second group of tanks.
The aircraft of any preceding clause, wherein the first group of tanks includes the first tank, a second tank, and a third tank fluidly coupled together in series via a first set of LH2 transfer flowlines and a first set of GH2 transfer flowlines, and wherein the second group of tanks includes a fourth tank, a fifth tank, and a sixth tank fluidly coupled together in series via a second set of LH2 transfer flowlines and a second set of GH2 transfer flowlines.
The aircraft of any preceding clause, wherein the first group of tanks and the second group of tanks are fluidly coupled together in parallel via a third set of LH2 flowlines and a third set of GH2 flowlines.
The aircraft of any preceding clause, further including a pair of wings connected to the fuselage and configured to generate a wing center of lift, wherein the integrated cryogenic hydrogen tank system defines a center of gravity aligned with the wing center of lift, the center of gravity based on a combination of a first center of gravity corresponding to the first tank, a second center of gravity corresponding to the second tank, a third center of gravity corresponding to the third tank, a fourth center of gravity corresponding to the fourth tank, a fifth center of gravity corresponding to the fifth tank, and a sixth center of gravity corresponding to the sixth tank.
The aircraft of any preceding clause, wherein the second center of gravity, the fifth center of gravity, and the wing center of lift are aligned along a reference line oriented transverse to the centerline.
The aircraft of any preceding clause, wherein the internal chamber of the first tank includes a lower portion and an upper portion, the LH2 extraction flowline fluidly coupled to the lower portion of the internal chamber.
The aircraft of any preceding clause, wherein the integrated cryogenic hydrogen tank system includes a GH2 extraction flowline fluidly coupled to the upper portion of the internal chamber.
The aircraft of any preceding clause, wherein each tank of the integrated cryogenic hydrogen tank system includes an outer vessel and an inner vessel within the outer vessel, the internal chamber located within the inner vessel.
The aircraft of any preceding clause, wherein each tank of the integrated cryogenic hydrogen tank system includes suspensions extending between the inner vessel and the outer vessel, the inner vessel and the outer vessel including female threads, wherein the suspensions are hollow tubes having male threads configured to engage with the female threads of the inner vessel and the outer vessel.
The aircraft of any preceding clause, wherein the outer vessel has an outer vessel wall, wherein the inner vessel has an inner vessel wall, wherein the outer vessel wall has a first inner layer and a first outer layer, and wherein the inner vessel wall has a second inner layer and a second outer layer.
The aircraft of any preceding clause, wherein the female threads of the outer vessel are positioned in the first inner layer, and wherein the female threads of the inner vessel are positioned in the second outer layer.
The aircraft of any preceding clause, wherein the first and second inner layers are constructed of metal, and wherein the first and second outer layers are constructed of a composite material.
The aircraft of any preceding clause, wherein each tank of the integrated cryogenic hydrogen tank system includes a gap between the outer vessel and the inner vessel, the gap having a vacuum pressure to provide thermal isolation for the inner vessel.
The aircraft of any preceding clause, wherein each tank of the integrated cryogenic hydrogen tank system includes multi-layer insulation in the gap.
A sub-cooler for refueling an integrated cryogenic hydrogen tank system, the sub-cooler comprising a first valve to separate a liquid hydrogen (LH2) fuel into a primary flowline and an auxiliary flowline, wherein the LH2 fuel in the primary flowline has a first temperature, and wherein the LH2 fuel in the auxiliary flowline has a second temperature, the primary flowline fluidly coupled to a tank of the integrated cryogenic hydrogen tank system to provide sub-cooled LH2 fuel to the integrated cryogenic hydrogen tank system, a second valve to reduce the second temperature of the LH2 fuel in the auxiliary flowline by reducing a saturated pressure in the auxiliary flowline, a cryogenic heat exchanger to reduce the first temperature of the LH2 fuel in the primary flowline by transferring heat from the primary flowline to the auxiliary flowline, a temperature sensor to measure a measured temperature of the LH2 fuel in the primary flowline downstream of the cryogenic heat exchanger, and a sub-cooler controller including a temperature loop controller and a position loop controller configured to regulate the first temperature.
The sub-cooler of any preceding clause, wherein the first valve is a proportional valve.
The sub-cooler of any preceding clause, wherein the second valve is an expansion valve.
The sub-cooler of any preceding clause, wherein the primary flowline and the auxiliary flowline are vacuum jacketed flowlines.
The sub-cooler of any preceding clause, wherein the primary flowline includes a flowmeter downstream of the cryogenic heat exchanger to measure a volumetric flowrate of the LH2 fuel.
The sub-cooler of any preceding clause, wherein the primary flowline includes a cryogenic valve downstream of the cryogenic heat exchanger to regulate flow of the LH2 fuel to an onboard cryogenic fuel tank.
The sub-cooler of any preceding clause, wherein the cryogenic heat exchanger includes a second flowline to direct the auxiliary flowline to a vaporizer, the vaporizer to convert the LH2 fuel into a gas.
The sub-cooler of any preceding clause, wherein the vaporizer includes a flowline to direct the gas to a compressor, the compressor to pressurize the gas in a storage tank.
At least one non-transitory computer-readable medium comprising instructions that, when executed, cause a sub-cooler controller to at least separate a cryogenic fuel into a primary flowline and an auxiliary flowline by actuating a first valve, wherein the cryogenic fuel in the primary flowline has a first temperature, and wherein the cryogenic fuel in the auxiliary flowline has a second temperature, the primary flowline fluidly coupled to a tank of an integrated cryogenic hydrogen tank system to provide sub-cooled LH2 fuel to the integrated cryogenic hydrogen tank system, reduce the second temperature of the cryogenic fuel in the auxiliary flowline by reducing a saturated pressure in the auxiliary flowline using a second valve, reduce the first temperature of the cryogenic fuel in the primary flowline by transferring heat from the primary flowline to the auxiliary flowline using a cryogenic heat exchanger, measure a measured temperature of the cryogenic fuel in the primary flowline downstream of the cryogenic heat exchanger with a temperature sensor, and control a sub-cooler using a temperature loop controller and a position loop controller configured to regulate the first temperature of the sub-cooler.
The at least one non-transitory computer-readable medium of any preceding clause, wherein the instructions are to cause the sub-cooler controller to separate the cryogenic fuel into the primary flowline and the auxiliary flowline by actuating a proportional valve.
The at least one non-transitory computer-readable medium of any preceding clause, wherein the instructions are to cause the sub-cooler controller to measure a volumetric flowrate of the cryogenic fuel with a flowmeter at the primary flowline downstream of the cryogenic heat exchanger.
The at least one non-transitory computer-readable medium of any preceding clause, wherein the instructions are to cause the sub-cooler controller to regulate flow of the cryogenic fuel to an onboard cryogenic fuel tank using a cryogenic valve at the primary flowline downstream of the cryogenic heat exchanger.
The at least one non-transitory computer-readable medium of any preceding clause, wherein the instructions are to cause the sub-cooler controller to adjust a pressure setting of a vaporizer at the auxiliary flowline downstream of the cryogenic heat exchanger, the vaporizer to convert the cryogenic fuel into a gas.
The at least one non-transitory computer-readable medium of any preceding clause wherein the instructions are to cause the sub-cooler controller to adjust a compression ratio of a compressor at the auxiliary flowline downstream of the vaporizer, the compressor to pressurize the gas in a storage tank.
A method to refuel an integrated cryogenic hydrogen tank system of an aircraft, the method comprising controlling a sub-cooler of a cryogenic refueling system including determining, using a first controller, a commanded first valve actuator position based on at least a source temperature and a target temperature, determining, using the first controller, an error between a measured temperature from a temperature sensor and the target temperature, determining, using the first controller, the commanded first valve actuator position based on the error and a preceding commanded first valve actuator position, determining, using a second controller, an actual first valve actuator position based on the commanded first valve actuator position, and generating, using the second controller, a primary first valve effective area and an auxiliary first valve effective area based on the actual first valve actuator position.
The method of any preceding clause, including generating a pressure differential across the cryogenic refueling system, wherein a first pressure upstream of the sub-cooler is greater than a second pressure within the integrated cryogenic hydrogen tank system.
The method of any preceding clause, including regulating flow, via a cryogenic valve, of a cryogenic fuel in a primary flowline to the integrated cryogenic hydrogen tank system.
The method of any preceding clause, further including measuring one or more volumetric flowrates, via a flowmeter, of the cryogenic fuel in the primary flowline downstream of a cryogenic heat exchanger, measuring the measured temperature, via the temperature sensor, of the cryogenic fuel in the primary flowline downstream of the cryogenic heat exchanger, determining a volume of the cryogenic fuel supplied to the integrated cryogenic hydrogen tank system based on the one or more volumetric flowrates and one or more time periods of the one or more volumetric flowrates, determining a density of the cryogenic fuel based on at least the measured temperature of the cryogenic fuel and thermodynamic properties of the cryogenic fuel, and determining a mass of the cryogenic fuel supplied to the integrated cryogenic hydrogen tank system based on at least the volume of the cryogenic fuel supplied to the integrated cryogenic hydrogen tank system and the density of the cryogenic fuel.
The method of any preceding clause, including directing, via a cryogenic heat exchanger, an auxiliary flowline to a storage tank.
The method of any preceding clause, further including directing, via the cryogenic heat exchanger, the auxiliary flowline to a vaporizer, vaporizing, via the vaporizer, a cryogenic fuel into a gas, and pressurizing, via a compressor, the gas in the storage tank.
A phase separating liquid hydrogen (LH2) pump system comprising an integrated cryogenic hydrogen tank system for storing LH2 fuel, the integrated cryogenic hydrogen tank system including at least two tanks coupled together, wherein a first tank of the integrated cryogenic hydrogen tank system includes a LH2 extraction flowline, a LH2 pump including a suction adapter, the suction adapter connected to the first tank via the LH2 extraction flowline and a gaseous hydrogen (GH2) return flowline, and a phase separator coupled to the first tank via a first portion of the LH2 extraction flowline, the phase separator coupled to the LH2 pump via a second portion of the LH2 extraction flowline, the phase separator positioned downstream of the first tank and upstream of the LH2 pump, the phase separator including a filtration structure and a vapor accumulator, the filtration structure coupled to the first portion and the second portion to separate hydrogen vapor from the LH2 fuel, the vapor accumulator coupled to the GH2 return flowline to direct the hydrogen vapor to the integrated cryogenic hydrogen tank system.
The cryogenic pump system of any preceding clause, wherein the filtration structure is a porous metallic structure that is constructed of multiple layers of powdered metal fused together.
The cryogenic pump system of any preceding clause, wherein filtration structure includes at least one of titanium, an aluminum-based alloy, or an austenitic steel alloy.
The cryogenic pump system of any preceding clause, wherein the LH2 extraction flowline and the GH2 return flowline are vacuum jacketed flowlines.
The cryogenic pump system of any preceding clause, wherein the LH2 extraction flowline and the GH2 return flowline are coupled to the phase separator via bayonet connections.
The cryogenic pump system of any preceding clause, wherein the phase separator includes a vacuum insulation layer positioned between an inner vessel and an outer vessel.
The cryogenic pump system of any preceding clause, wherein the GH2 return flowline includes a first portion coupled to the first tank, a second portion coupled to the phase separator and the first portion, and a third portion coupled to the suction adapter and the first portion.
The cryogenic pump system of any preceding clause, further including a GH2 tank coupled to the second portion via a first regulator valve and coupled to the third portion via a second regulator valve, and a first pressure sensor in the integrated cryogenic hydrogen tank system, a second pressure sensor in the second portion, and a third pressure sensor in the third portion.
The cryogenic pump system of any preceding clause, further including a controlling device to obtain a first pressure measurement from the first pressure sensor, a second pressure measurement from the second pressure sensor, and a third pressure measurement from the third pressure sensor, determine whether a first pressure differential between the first and second pressure measurements satisfies a threshold, determine whether a second pressure differential between the first and third pressure measurements satisfies the threshold, determine whether a third pressure differential between the second and third pressure measurements satisfies the threshold, and in response to determining that the first, second, or third pressure differential does not satisfy the threshold, adjust one or more pressure outputs of the first or second regulator valves.
An apparatus for separating gaseous hydrogen (GH2) from liquid hydrogen (LH2) upstream of an LH2 pump, the apparatus comprising a phase separator integrated into an LH2 extraction flowline and a GH2 return flowline, the phase separator including a filtration structure and a vapor accumulator, the GH2 return flowline including a first GH2 portion upstream from an integrated cryogenic hydrogen tank system, a second GH2 portion downstream of the vapor accumulator, and a third GH2 portion downstream of the LH2 pump, the integrated cryogenic hydrogen tank system including a first pressure sensor, the second GH2 portion including a second pressure sensor, and the third GH2 portion including a third pressure sensor, a GH2 storage tank connected to the second GH2 portion via a first regulator valve and the third GH2 portion via a second regulator valve, and a controlling device configured to determine pressure differentials between pressure measurements of at least two of the first, second, and third pressure sensors, determine whether the pressure differentials satisfy a threshold, and when at least one of the pressure differentials does not satisfy the threshold, increase a pressure output of at least one of the first or second regulator valves.
The apparatus of any preceding clause, wherein the filtration structure is a porous metallic structure that is constructed of multiple layers of powdered metal fused together.
The apparatus of any preceding clause, wherein filtration structure includes at least one of titanium, an aluminum-based alloy, or an austenitic steel alloy.
The apparatus of any preceding clause, wherein the LH2 extraction flowline and the GH2 return flowline are vacuum jacketed flowlines.
The apparatus of any preceding clause, wherein the phase separator includes an inner vessel, an outer vessel, and a vacuum insulation layer positioned between the inner vessel and the outer vessel.
The apparatus of any preceding clause, wherein the vacuum insulation layer of the phase separator is open to a vacuum insulation layer of the LH2 extraction flowline and a vacuum insulation layer of the GH2 return flowline.
The apparatus of any preceding clause, wherein the LH2 pump includes a suction adapter, a pump cold end, a motor, and a discharge flowline to output compressed LH2 from the pump cold end.
A method comprising detecting first, second, and third pressure measurements, the first pressure measurement corresponding to a first vapor pressure in an integrated cryogenic hydrogen tank system, the second pressure measurement corresponding to a second vapor pressure in a first portion of a gaseous hydrogen (GH2) return flowline, the third pressure measurement corresponding to a third vapor pressure in a second portion of the GH2 return flowline, and adjusting at least one of a pressure output of a first regulator valve or a pressure output of a second regulator valve to drive GH2 from a phase separator to the integrated cryogenic hydrogen tank system.
The method of any preceding clause, further including calculating a first pressure differential between the first and second pressure measurements, calculating a second pressure differential between the first and third pressure measurements, and calculating a third pressure differential between the second and third pressure measurements.
The method of any preceding clause, further including determining whether the first, second, or third pressure differentials satisfy a threshold.
The method of any preceding clause, wherein adjusting the pressure output of the first regulator valve and the pressure output of the second regulator valve includes increasing the pressure output of the first regulator valve in response to the first pressure differential not satisfying the threshold, and increasing the pressure output of the second regulator valve in response to the second or third pressure differentials not satisfying the threshold.
A fuel cell power system for a vehicle having a propulsor, the propulsor configured to generate thrust for the vehicle and a flow of compressed air, the fuel cell power system comprising a fuel delivery system for providing a flow of hydrogen fuel, the fuel delivery system comprising an integrated cryogenic hydrogen tank system for storing hydrogen fuel, and a fuel cell stack configured to be located remotely from the propulsor and in airflow communication with the propulsor for receiving the flow of compressed air from the propulsor, the fuel cell stack further in fluid communication with the fuel delivery system for receiving the flow of hydrogen fuel from the fuel delivery system.
The fuel cell power system of any preceding clause, further including a battery heat exchanger in thermal communication with the fuel cell stack and in thermal communication with the fuel delivery system.
The fuel cell power system of any preceding clause, further including a humidifier in airflow communication with the fuel cell stack.
The fuel cell power system of any preceding clause, further including a heat exchanger in airflow communication with the propulsor, wherein the heat exchanger is located upstream of the fuel cell stack and is in thermal communication with the fuel delivery system.
The fuel cell power system of any preceding clause, wherein the propulsor is an electric propulsor.
The fuel cell power system of any preceding clause, wherein the electric propulsor includes a low-pressure compressor providing at least a portion of the flow of compressed air and an electric motor.
The fuel cell power system of any preceding clause, wherein the propulsor is a part of a turbomachine comprising an engine, wherein a downstream section of a nacelle extends over an outer portion of the engine so as to define a bypass airflow passage therebetween, the bypass airflow passage providing at least a portion of the flow of compressed air.
The fuel cell power system of any preceding clause, wherein air from the bypass airflow passage comprises all of the flow of compressed air in the flow of compressed air.
The fuel cell power system of any preceding clause, further including a coolant pump, and a hydrogen/coolant heat exchanger.
The fuel cell power system of any preceding clause, further including a startup hydrogen tank, the startup hydrogen tank comprising a high-pressure tank configured for storing gaseous hydrogen fuel.
The fuel cell power system of any preceding clause, further including a power converter, and at least one electric machine, wherein the power converter, the at least one electric machine, or both are in thermal communication with the fuel delivery system.
The fuel cell power system of any preceding clause, further including a pump motor, a liquid hydrogen fuel pump fluidly coupled to a tank of the integrated cryogenic hydrogen tank system and operably coupled to the pump motor, and a power converter in electrical communication with the pump motor.
A vehicle comprising a propulsor operable to provide thrust for the vehicle and to generate a flow of compressed air, and a fuel cell power system including a fuel delivery system comprising an integrated cryogenic hydrogen tank system for storing hydrogen fuel, and a fuel cell stack located remotely from the propulsor and in airflow communication with the propulsor to receive the flow of compressed air from the propulsor, the fuel cell stack further in fluid communication with the integrated cryogenic hydrogen tank system to receive a flow of hydrogen fuel.
A method of powering an aircraft, the aircraft including a propulsor having an engine of the aircraft and a fuel cell power system comprising a fuel cell stack, the method comprising operating the propulsor to create a flow of compressed air, providing the flow of compressed air to the fuel cell power system, providing a flow of hydrogen fuel from a fuel delivery system to one or more engine heat exchangers positioned within the engine, providing the flow of hydrogen fuel from the one or more engine heat exchangers to a heat exchanger located upstream of the fuel cell stack, and exchanging heat between the flow of compressed air and the flow of hydrogen fuel with the heat exchanger.
The method of any preceding clause, wherein the flow of compressed air is created in a bypass airflow passage, a low-pressure compressor, or both.
The method of any preceding clause, wherein the flow of hydrogen fuel is a first flow of hydrogen fuel, further including providing a second flow of hydrogen fuel from the fuel delivery system directly to a fuel cell stack of the fuel cell power system.
The method of any preceding clause, further including using a startup heater to heat the hydrogen fuel before the hydrogen fuel is provided to the fuel cell stack.
The method of any preceding clause, wherein fuel cell power system includes a humidifier, further including humidifying the compressed air before recirculating the compressed air to the fuel cell stack.
The method of any preceding clause, wherein the fuel cell power system includes a separator and a recirculation pump, further including separating exhaust water from the flow of hydrogen fuel, and ejecting the exhaust water through an exhaust section of the aircraft.
The method of any preceding clause, wherein the fuel cell power system includes a power converter and a phase separating liquid hydrogen pump system, the phase separating liquid hydrogen pump system including a phase separator fluidly coupled between a liquid hydrogen pump and an integrated cryogenic hydrogen tank system, further including providing a second flow of hydrogen fuel from the integrated cryogenic hydrogen tank system to the liquid hydrogen pump, converting the flow of hydrogen fuel to electric power via the power converter, and providing at least a portion of the electric power to a motor of the liquid hydrogen pump.
A fuel distribution system including an integrated cryogenic hydrogen tank system including at least two tanks fluidly coupled together, a first sensor associated with the integrated cryogenic hydrogen tank system, a second sensor associated with a combustor, and a controller to determine a first rate of change in a first amount of hydrogen in the integrated cryogenic hydrogen tank system based on a first input from the first sensor, determine a flow rate of hydrogen into the combustor based on a second input from the second sensor, determine an average mass loss rate based on the first rate of change and the flow rate, and in response to determining the average mass loss rate satisfies a first threshold, determine a leak is present in the fuel distribution system.
The fuel distribution system of any preceding clause, wherein the controller is further to determine a second rate of change in a second amount of hydrogen in a second tank, and the controller further determines the average mass loss rate based on the second rate of change.
The fuel distribution system of any preceding clause, wherein the integrated cryogenic hydrogen tank system includes at least liquid hydrogen tanks fluidly coupled together, and wherein the second tank is a gaseous hydrogen fuel tank.
The fuel distribution system of any preceding clause, wherein the controller is further to in response to determining the average mass loss rate satisfies a second threshold, determine at least one of the first sensor or the second sensor requires recalibration, and issue a notification to recalibrate the first sensor or the second sensor.
The fuel distribution system of any preceding clause, wherein the controller is, in response to determining the average mass loss rate satisfies the first threshold, further to identify a location of the leak in the fuel distribution system, and isolate the location in the fuel distribution system.
The fuel distribution system of any preceding clause, wherein the first threshold is zero.
A non-transitory computer readable medium comprising instructions, which, when executed, cause a processor to determine a first rate of change in a first amount of hydrogen in an integrated cryogenic hydrogen tank system based on a first input from a first sensor associated with the integrated cryogenic hydrogen tank system, determine a flow rate of hydrogen into a combustor of a gas turbine engine based on a second input from a second sensor associated with the combustor, the combustor coupled to the integrated cryogenic hydrogen tank system via a fuel distribution system, determine an average mass loss rate based on the first rate of change and the flow rate, and in response to determining the average mass loss rate satisfies a first threshold, determine a leak is present in the fuel distribution system.
The non-transitory computer readable medium of any preceding clause, wherein the instructions when executed, cause the processor to determine a second rate of change in a second amount of hydrogen in a second tank, and further determine the average mass loss rate based on the second rate of change.
The non-transitory computer readable medium of any preceding clause, wherein the integrated cryogenic hydrogen tank system includes at least two liquid hydrogen tanks fluidly coupled together, and wherein the second tank is a gaseous hydrogen fuel tank.
The non-transitory computer readable medium of any preceding clause, wherein the instructions when executed, cause the processor to in response to determining the average mass loss rate satisfies a second threshold, determine at least one of the first sensor or the second sensor requires recalibration, and issue a notification to recalibrate the first sensor or the second sensor.
The non-transitory computer readable medium of any preceding clause, wherein the instructions when executed, cause the processor to in response to determining the average mass loss rate satisfies the first threshold identify a location of the leak in the fuel distribution system, and isolate the location in the fuel distribution system.
The non-transitory computer readable medium of any preceding clause, wherein the first threshold is zero.
A method comprising determining a first rate of change in a first amount of hydrogen in an integrated cryogenic hydrogen tank system based on a first input from a first sensor associated with the integrated cryogenic hydrogen tank system, determining a flow rate of hydrogen into a combustor of a gas turbine engine based on a second input from a second sensor associated with the combustor, the combustor coupled to the integrated cryogenic hydrogen tank system via a fuel distribution system, determining an average mass loss rate based on the first rate of change and the flow rate, and determining a leak is present in the fuel distribution system when the average mass loss rate satisfies a first threshold.
The method of any preceding clause, further including determining a second rate of change in a second amount of hydrogen in a second tank, and further determining the average mass loss rate based on the second rate of change.
The method of any preceding clause, wherein the integrated cryogenic hydrogen tank system includes at least two liquid hydrogen fuel tanks fluidly coupled together, and wherein the second tank is a gaseous hydrogen fuel tank.
The method of any preceding clause, further including determining at least one of the first sensor or the second sensor requires recalibration when the average mass loss rate satisfies a second threshold, and issuing a notification to recalibrate the first sensor or the second sensor.
The method of any preceding clause, further including, in response to determining the average mass loss rate satisfies the first threshold identifying a location of the leak in the fuel distribution system, and isolating the location in the fuel distribution system.
The method of any preceding clause, wherein the first threshold is zero.
A system comprising a plurality of compartments positioned within a vehicle, the plurality of compartments configured to isolate internal gases from external gases, the plurality of compartments including a first compartment, an integrated cryogenic hydrogen tank system including a first liquid hydrogen (LH2) tank fluidly coupled to a plurality of LH2 tanks, the first LH2 tank positioned within the first compartment, and a computing system configured to determine a level of hydrogen present within the first compartment based on a concentration measurement obtained from a hydrogen sensor associated with the first compartment, compare the level of hydrogen to a first threshold value, and cause the level of hydrogen to reduce when the level of hydrogen exceeds the first threshold value.
The system of any preceding clause, wherein the computing system is configured to determine a rate of change of the level of hydrogen present within the first compartment based on concentration measurements obtained over time from the hydrogen sensor, compare the rate of change of the level of hydrogen to a second threshold value, and cause the level of hydrogen to reduce when the rate of change of the level of hydrogen exceeds the second threshold value.
The system of any preceding clause, further including a ventilation device associated with the first compartment, the ventilation device including louvers, wherein the computing system is to cause the louvers to open when (i) the level of hydrogen exceeds the first threshold value or (ii) the rate of change of the level of hydrogen exceeds the second threshold value.
The system of any preceding clause, wherein the ventilation device includes a fan configured to draw air into the first compartment, and wherein the computing system is to activate the fan when the louvers are open.
The system of any preceding clause, further including a quick release panel associated with the first compartment, the quick release panel including a frangible portion defining a portion of a wall of the first compartment.
The system of any preceding clause, wherein the quick release panel includes an actuator operatively coupled to a stake, the computing system to cause the actuator to drive the stake through the frangible portion when (i) the level of hydrogen exceeds the first threshold value or (ii) the rate of change of the level of hydrogen exceeds the second threshold value.
The system of any preceding clause, wherein the frangible portion is configured to open when a pressure within the first compartment exceeds a pressure threshold.
The system of any preceding clause, further including a ventilation valve associated with the first compartment.
The system of any preceding clause, wherein the computing system is to cause the ventilation valve to open when (i) the level of hydrogen exceeds the first threshold value or (ii) the rate of change of the level of hydrogen exceeds the second threshold value.
The system of any preceding clause, wherein the first LH2 tank is fluidly coupled to a phase separating LH2 pumping system, the phase separating LH2 pumping system including a phase separator, a LH2 pump, an LH2 extraction flowline, and a gaseous hydrogen (GH2) return flowline.
The system of any preceding clause, wherein the plurality of compartments includes a second compartment, and wherein phase separating LH2 pumping system is positioned within the second compartment.
The system of any preceding clause, wherein the LH2 extraction flowline includes a first LH2 portion and a second LH2 portion, the first LH2 portion coupled to the first LH2 tank and the phase separator, the second LH2 portion coupled to the phase separator and the LH2 pump.
The system of any preceding clause, wherein the GH2 return flowline includes a first GH2 portion, a second GH2 portion, and a third GH2 portion, the first GH2 portion coupled to the first LH2 tank, the second GH2 portion coupled to the first GH2 portion and the phase separator, the third GH2 portion coupled to the first GH2 portion and the LH2 pump.
The system of any preceding clause, wherein the plurality of compartments includes a second compartment, and wherein the LH2 pump, the second LH2 portion, and the third GH2 portion are positioned within the second compartment.
The system of any preceding clause, wherein the plurality of compartments includes a second compartment, and wherein the phase separator, the first LH2 portion, the second LH2 portion, and the second GH2 portion are included in the second compartment.
The system of example 1, wherein the integrated cryogenic hydrogen tank system includes the first LH2 tank and a second LH2 tank, the first LH2 tank positioned within the first compartment, the second LH2 tank positioned within a second compartment.
The system of any preceding clause, wherein the integrated cryogenic hydrogen tank system includes a first group of tanks and a second group of tanks.
The system of any preceding clause, wherein the plurality of compartments includes a second compartment, wherein the first group of tanks is positioned within the first compartment, and wherein the second group of tanks is positioned within the second compartment.
The system of any preceding clause, wherein the first group of tanks includes the first LH2 tank, a second LH2 tank, and a third LH2 tank, and wherein the second group of tanks includes a fourth LH2 tank, a fifth LH2 tank, and a sixth LH2 tank.
The system of any preceding clause, wherein the plurality of compartments includes the first compartment, a second compartment, a third compartment, a fourth compartment, a fifth compartment, and a sixth compartment.
The system of any preceding clause, wherein the first LH2 tank is positioned within the first compartment, the second LH2 tank is positioned within the second compartment, the third LH2 tank is positioned within the third compartment, the fourth LH2 tank is positioned within the fourth compartment, the fifth LH2 tank is positioned within the fifth compartment, and the sixth LH2 tank is positioned within the sixth compartment.
A method for detecting hydrogen leaks within a vehicle, the vehicle including a component in which hydrogen is stored or through which hydrogen flows, the component being positioned within a compartment of the vehicle, the method comprising receiving, with a computing system, hydrogen sensor data indicative of a level of hydrogen present within the compartment, determining, with the computing system, at least one of the level of hydrogen present within the compartment or a rate of change of the level of hydrogen present within the compartment based on the received hydrogen sensor data, comparing, with the computing system, the determined at least one of the level of hydrogen present within the compartment or the rate of change of the level of hydrogen present within the compartment to an associated threshold value, and initiating, with the computing system, a control action associated with reducing the level of hydrogen present within the compartment when the determined at least one of the level of hydrogen present within the compartment or the rate of change of the level of hydrogen present within the compartment exceeds the associated threshold value.
The method of any preceding clause, further comprising determining, with the computing system, the level of hydrogen present within the compartment based on the data generated by the hydrogen sensor, comparing, with the computing system, the determined level of hydrogen present within the compartment to the associated threshold value, and initiating, with the computing system, a control action associated with reducing the level of hydrogen present within the compartment when the determined level of hydrogen present within the compartment exceeds the associated threshold value.
The method of any preceding clause, further comprising determining, with the computing system, the rate of change of the level of hydrogen present within the compartment based on the data generated by the hydrogen sensor, comparing, with the computing system, the determined rate of change of the level of hydrogen present within the compartment to the associated threshold value, and initiating, with the computing system, a control action associated with reducing the level of hydrogen present within the compartment when the determined rate of change of the level of hydrogen present within the compartment exceeds the associated threshold value.
The following claims are hereby incorporated into this Detailed Description by this reference. Although certain example systems, methods, apparatus, and articles of manufacture have been disclosed herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all systems, methods, apparatus, and articles of manufacture fairly falling within the scope of the claims of this patent.
This invention was made with Government support under contract number 80NSSC19M0125 awarded by the National Aeronautics and Space Administration. The Government has certain rights in this invention.