Patent Application
20250237392
This invention relates generally to the field of heating ventilation and air conditioning and, more specifically, to new and useful systems and methods for solar thermal micro combined heating and power.
The following description of embodiments of the invention is not intended to limit the invention to these embodiments but rather to enable a person skilled in the art to make and use this invention. Variations, configurations, implementations, example implementations, and examples described herein are optional and are not exclusive to the variations, configurations, implementations, example implementations, and examples they describe. The invention described herein can include all permutations of these variations, configurations, implementations, example implementations, and examples.
Generally, the term “can,” as utilized herein, indicates an action or attribute of the system, which may or may not be executed by or be applicable to the system depending on the implementation or embodiment of the system.
Generally, the term “include,” as utilized herein, can mean “comprise,” “consist of,” or “consist essentially of” and is not restricted to any one of the above interpretations throughout.
Generally, the term “a set of,” as utilized herein, refers to one or more of the subject objects. Additionally, the terms “first,” “second,” “third,” etc., as utilized herein, do not imply an order but simply identify multiple instances of a step or component unless an order or series is otherwise implied.
Unless otherwise specified, the terms “at a first time,” “at a second time,” etc., as utilized herein, refer to operationally discrete time periods during which control actions are executed. Actions described as occurring “at a first time,” “at a second time,” etc., need not occur at exactly the same time but can occur within the same operationally discrete time period (e.g., with 1/60th of a second for a controller operating at 60 Hz).
Generally, each implementation described herein can be modified by one of skill in the art to adhere to present HVAC standards for zone control, drift constants, and other industry-standard practices.
Generally, the term “thermal energy storage unit” or “TES unit” may refer to either a stratified or non-stratified thermal energy storage unit.
Generally, the compound adjectives “array-to-storage,” “storage-to-array” “storage-to-generator,” “generator-to-storage,” “storage-to-air,” “air-to-storage,” “storage-to-water,” “water-to-storage,” “storage-to-cooler,” “cooler-to-storage,” “cooler-to-sink,” “sink-to-cooler” can indicate direct or indirect transmission of thermal energy. For example, the storage-to-air heat transfer device can imply that thermal energy is transferred directly to interior air of the structure or indirectly transferred via a hydronic system.
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In one variant of the system 100, the heat sink subsystem 104 further includes: a low temperature fluid reservoir 107; a heat sink refrigeration unit 108; and an exterior air cooling circuit 109.
In another variant, the stratified thermal energy storage unit 110 includes: an output valve array 170 configured to output a high-temperature fluid at a target output temperature; and an input valve array 190 configured to input the high-temperature fluid to the stratified energy storage unit at a target stratum in the set of input strata.
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In one variant, the method S500 also includes, in response to a target low temperature reservoir temperature exceeding an external air temperature, operating the exterior air cooling circuit 109 to lower a low temperature reservoir temperature of the low temperature fluid reservoir in Step S540.
In another variant, the method S500 includes, in response to a low temperature reservoir temperature exceeding a threshold heat sink temperature, operating the heat sink refrigeration unit 108 to reduce the temperature of the low temperature reservoir below the threshold heat sink temperature in Step S550.
A solar thermal combined heating, cooling, and power system 100 (hereinafter “the system 100”) for structures (e.g., residential and commercial structures with HVAC needs) includes: a solar thermal array 102 (e.g., a parabolic trough array) to collect solar energy, a thermal energy storage unit 110 (hereinafter “TES”) to store excess thermal energy for later use, a heat sink subsystem 104 to store heat sink capacity for air-cooling operations, and a generator unit 120 such as Stirling engine or organic Rankine cycle engine (hereinafter “ORC engine”) to convert thermal energy to electrical energy. Additionally, the system 100 includes a set of heat transfer devices (e.g., a set of variable speed pumps and heat exchangers) to transfer thermal energy between the aforementioned components of the system 100 and to provide air heating, cooling, and/or hot water to the structure. In particular, the system 100 provides an off-grid or grid-tied heating and power alternative to photovoltaic and battery systems, which are characterized by significant environmental impacts based on their material construction. The system 100 leverages efficiencies in thermal energy transfer from the solar thermal array 102 to the TES unit 110, and from the TES unit 110 to the interior air of the structure and the potable hot water supply of the structure. Additionally, the system 100 can include a thermomechanical cooling unit 130 (e.g., a Stirling chiller) to utilize thermal energy from the TES unit 110 to cool the interior air of the structure. Thus, the system 100 provides sufficient power heating, and/or cooling to off-grid or grid-tied structures while incurring lower upfront environmental costs than a comparable photovoltaic and battery system.
The system controls heat flow between components of the system 100 via a control unit 160 configured to operate (increase or decrease the rate of heat transfer via control signals) various heat exchangers and heat transfer devices of the system 100. The control unit 160 executes multiple control methods based on the current state of the system 100 (e.g., temperatures, heat transfer capacities, state-of-charge of the TES unit 110). More specifically, the control unit 160 can simultaneously execute a generator control method, an air-heating control method, a water-heating control method, and/or an air-cooling control method to satisfy heating and power demands for the structure. Additionally, the control unit 160 can execute a load reduction or compensation protocol to prioritize the distribution of electrical and thermal power throughout the system 100. For example, the control unit 160 can execute a load reduction protocol that prioritizes air heating over water heating, plug loads over both air heating and water heating, and generator operational loads over all other loads of the structure. Alternatively, the control unit 160 can execute a custom load reduction protocol specified by the user or an HVAC installer. Thus, the control unit 160 ensures operation of the system 100 in alignment with generalized human comfort priorities.
In order to execute multiple HVAC functions utilizing a single thermal source, the system 100 includes a stratified TES unit 110 characterized by an overspecified capacity and vertical form factor, resulting in temperature stratification within the high-temperature fluid (hereinafter “HTF”). The system also includes an electromechanical output-mixing valve array (hereinafter “output valve array 170”), which is controllable by the control unit 160 to generate an HTF output at the full range of temperatures within the stratified TES unit 110. Thus, the system 100 can control the output valve array 170 to output HTF fluid at a temperature specific to each function of the system 100. For example, the system 100 can output HTF at a maximum available temperature for use by the generator unit 120 and thermomechanical cooling unit 130 to increase the thermal gradient across these devices and, therefore, the efficiency of these devices. In another example, the system 100 can output HTF at lower temperatures to heat water for the potable hot water supply to ensure safe operation of an HTF-water heat exchanger and prevent the reduction in efficiency caused by nucleate boiling at the surface of the HTF-water heat exchanger.
Additionally, the system 100 includes an electromechanical input valve array 190, which is controllable to direct return HTF to an input stratum within the stratified TES unit 110 characterized by a similar temperature to the temperature of the return HTF, thereby preventing convection within the stratified TES unit 110. Thus, the system 100 can utilize the stratified TES unit 110, the output valve array 170, and the input valve array 190 to provide HTF fluid at multiple operational temperatures simultaneously while maintaining stratification within the TES unit 110. By utilizing a centralized TES unit 110, the cost of the system 100 is dramatically reduced, and thermal resources can be more efficiently distributed to various functions of the system 100.
Generally, the system 100 includes a solar thermal array 102 configured to collect and concentrate solar energy to heat an array of high-temperature fluid (hereinafter “array HTF”). More specifically, the system 100 can include solar thermal array 102 types such as parabolic troughs, fresnel reflectors, flat plates, and/or any other solar thermal array 102 design based on the site specifics such as available space, topography, global location, and local weather conditions. Additionally, the solar thermal array 102 can include heliostats to track the position of the sun to increase solar energy uptake during low-angle conditions. The system includes a solar thermal array 102 with a collection area sufficient to satisfy heating and power requirements for the structure. A solar thermal array 102 sized for a residential structure can heat the array HTF to in excess of 400° C., which is high enough to drive thermomechanical processes of both the generator unit 120 and the thermomechanical cooling unit 130. Thus, the specific design and capacity of the solar thermal array 102 are set in advance of the operation of the system 100. However, the system 100 can operate flexibly in the absence of sufficient solar thermal power, as is further described below.
In one implementation, the solar thermal array 102 utilizes the same HTF as the TES unit 110 to enable direct HTF circulation between the solar thermal array 102 and the TES unit 110 without the use of an array-to-storage heat exchange unit. In this implementation, the system 100 directs hot HTF to an input stratum corresponding to the current input temperature of the hot HTF within the stratified TES unit 110 and returns cold HTF from the bottom or coldest stratum of the stratified TES unit 110 to the solar thermal array 102 for heating.
In another implementation, the solar thermal array 102 utilizes a different array HTF than the TES HTF. In this implementation, the system 100 can include an array-to-storage heat exchange unit to transfer thermal energy from the array HTF to the TES HTF. The system then directs the heated TES HTF to the input stratum corresponding to the current temperature of the TES HTF and returns cold TES HTF from the coldest stratum of the stratified TES unit 110.
Generally, the system 100 includes a thermal energy storage unit 110 or stratified TES unit 110 to which the system 100 transfers thermal energy for storage and later distribution. More specifically, the system 100 can include a stratified TES unit 110 such as a sensible heat storage TES unit 110, molten salt TES unit 110, pebble bed TES unit 110, latent heat TES unit 110, and/or any other form of TES unit 110 or thermal battery technology. Additionally, the system 100 includes a set of HTF circuits configured to distribute thermal energy to various subsystems including the generator unit 120, the air conditioning subsystem or the air-heating subsystem 300 and the air-cooling subsystem 500, and/or the water-heating subsystem 400. The HTF included within the TES unit 110 may be chosen based on the particular application of the system 100 and is characterized by chemical and physical stability up to 300-400° C. The HTF can include high-temperature oils (e.g., biphenyl-diphenyl oxide-based oils, silicon-based oils, mineral-based oils) or molten salts that remain liquid within a similar temperature range.
In the stratified TES variant, the system 100 includes a stratified TES unit 110 characterized by a greater vertical dimension relative to its volume. Additionally, the stratified TES unit 110 can be characterized by a greater thermal capacity than the power and heating needs of the structure would suggest from an energy storage perspective, in order to provide a larger temperature range for various heat transfer functions of the system 100. In this variant, the stratified TES unit 110 includes an output valve array 170 and an input valve array 190 to enable HTF output across the full range of temperatures available across the strata of the stratified TES unit 110 and to prevent convection within the stratified TES unit 110 upon returning cold HTF to the stratified TES unit 110. The stratified TES unit 110 defines a set of output strata 112, each of which includes an output stratum temperature sensor and a stratum outlet, thereby enabling the selective mixing of HTF of various temperatures by the output valve array 170. Additionally, the stratified TES unit 110 defines a set of input strata 114, each of which includes an input stratum temperature sensor and a stratum inlet, thereby enabling the selective input of cold HTF fluid to an input stratum that reduces convection within the stratified TES unit 110.
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In one implementation, the generator unit 120 includes a generator cooling circuit 126 configured to circulate low-temperature fluid (hereinafter “LTF”) from the cold side of the generator unit 120 to an exterior heat exchanger 128 to release heat from the generator unit 120 into the environment. The exterior heat exchanger is sized such that the LTF is returned to a sufficiently cold temperature (e.g., less than 50° C.) upon exchange with the exterior environment of the structure. The closed loop cooling circuit can include a LTF such as water with an environmentally friendly antifreeze (such as propylene glycol or glycerin), as is described with respect to the heat sink subsystem 104. In one example, the exterior heat exchanger can include electromechanically actuated valves configured to increase or decrease the effective surface area of the exterior heat exchanger, thereby enabling the system 100 to adjust the rate of heat exchange with the exterior environment based on the temperature of the exterior environment. Thus, the closed-loop cooling circuit can ensure the maintenance of an efficient temperature gradient across the generator unit 120 in a variety of weather conditions.
In another implementation, the generator unit 120 includes a generator cooling circuit configured to circulate water from the hot water reservoir through the cold side of the generator unit 120, such that the waste heat from the generator can be efficiently utilized by the system 100 to facilitate hot water heating while also providing a sufficient temperature gradient for the generator unit 120 to maintain its function. In this implementation, the system 100 includes: a generator-to-water circuit configured to circulate water between the hot water reservoir and the generator unit 120; and a generator-to-water heat exchanger configured to transfer thermal energy from the cold side of the generator unit 120 to the hot water in the generator-to-water circuit.
Generally, the system 100 includes a heat sink subsystem 104 configured to provide and maintain a heat sink for the thermomechanical cooling unit 130 resulting in a temperature gradient across the thermomechanical cooling unit 130, thereby enabling the thermomechanical cooling unit 130 to effectively cool the interior air of the structure. More specifically, the LTF reservoir can define an insulated internal volume housing an LTF, which can be circulated to other components of the system 100 via the heat transfer devices described below. The the system 100 can utilize an LTF including but not limited to water with environmentally friendly anti-freeze, such as propylene glycol or glycerin (or any other anti-freeze) or any other fluid with a freezing point below the expected operating temperatures of the heat sink subsystem 104 (e.g., −20 Celsius).
The heat sink subsystem 104 can include a heat sink refrigeration unit 108 or heat pump configured to cool the LTF reservoir in response to the LTF temperature exceeding a threshold temperature (e.g., 10° C.). In one implementation, the heat sink refrigeration unit 108 includes a solid state refrigeration unit (e.g., a thermoelectric cooler, a magnetocaloric cooler). Thus, the system 100 can cool the temperature of the LTF reservoir to increase the capacity of the provided heat sink in preparation for periods of air-cooling operation. The high capacity of the LTF reservoir enables the system 100 to include a relative low power heat sink refrigeration unit 108
The heat sink subsystem 104 can also include an exterior air cooling circuit 109 configured to circulate LTF to exchange heat with the exterior when the exterior air temperature is below the current temperature of the LTF.
The heat sink subsystem 104 can include an LTF reservoir characterized by a high volume (e.g., 1000 gallons for a 2000 squarefoot house), to enable a higher thermal mass and, therefore, a more stable temperature during operation of the system 100.
Generally, the system 100 includes an air conditioning subsystem 106 configured to heat or cool the structure, depending on the set temperature of the interior air of the structure and the current temperature of the interior air of the structure. In a heating-only variant, the air conditioning subsystem includes only the air-heating subsystem 300, further described below. In a separate heating and cooling variant, the air conditioning subsystem includes both an air-heating subsystem 300 and an air-cooling subsystem 500, further described below. In a combined heating and cooling variant, the air conditioning subsystem includes a combined heating and cooling subsystem, further described below. Thus, the system 100 can effectively maintain the temperature of the structure utilizing thermal and electrical power derived from the solar thermal array 102.
The system includes an air-heating subsystem 300 configured to receive heat from the TES unit 110 and distribute this heat into the interior air of the structure. More specifically, the system 100 can support either hydronic or forced air heating subsystems, each of which is described in further detail below.
In one implementation, the system 100 can include a hydronic heating system that utilizes a hydronic fluid (e.g., water) to receive heat from the TES HTF via a liquid-liquid heat exchanger before circulating the heated hydronic fluid around the structure. More specifically, in this implementation, the system 100 can include a storage-to-air heat exchanger configured to transfer thermal energy from the HTF to a hydronic fluid; a storage-to-air HTF pump configured to circulate the HTF between the stratified TES unit 110 and the storage-to-air heat exchanger; and a hydronic heating circuit configured to circulate a hydronic fluid between the storage-to-air heat exchanger and the structure to heat an interior air volume of the structure. Thus, in this implementation, the system 100 utilizes a high-efficiency air-heating subsystem 300. However, due to HTF fluid temperatures generally exceeding the boiling temperature of the hydronic fluid, the system 100 can include additional pressure release systems to mitigate the chance of a steam explosion within the liquid-liquid heat exchanger.
In another implementation, the system 100 can include a forced air heating system utilizing a liquid-gas heat exchanger to transfer thermal energy directly from the TES HTF to the interior air of the structure. Thus, in this implementation, the air-heating subsystem 300 is characterized by reduced mechanical complexity but lower efficiency due to the low efficiency of the liquid-gas heat exchanger and a forced air-heating system.
Generally, the system 100 includes a thermomechanical cooling unit 130 and air-cooling subsystem 500 configured to utilize thermal energy from the TES unit 110 to extract thermal energy from the interior air of the structure. More specifically, the thermomechanical cooling unit 130 utilizes a thermomechanical cycle (e.g., the Stirling cycle) to extract thermal energy from a working fluid of the air-cooling subsystem 500. The system can include a chilled beam air-cooling subsystem 500 (active or passive) or a forced air air-cooling subsystem 500. In either implementation, the system 100 utilizes the LTF from the LTF reservoir for the cold side of the thermomechanical cooling unit 130 (e.g., the isochoric cooling phase of the Stirling cycle) and utilizes the HTF from the TES unit 110 for the hot side of the thermomechanical cooling unit 130 (e.g., the isochoric heating phase of the Stirling cycle). In implementations of the thermomechanical cooling unit 130 including a Stirling cooler, the Stirling cooler imparts a cooling effect to the water or air of the air-cooling subsystem 500 during the isothermal expansion phase of the Stirling cycle. The air-cooling subsystem 500 then circulates the cooled fluid, either water (in the chilled beam implementation) or air (in the forced air implementation).
In a combined heating and cooling variant, the system 100 can include a combined heating and cooling subsystem configured to either heat or cool the interior air of the structure via the storage-to-air heat exchanger or via the thermomechanical cooling unit 130 respectively. The combined heating and cooling subsystem can include a shared storage-to-air HTF circuit 143 configured to transfer heat to a storage-to-air heat exchanger or a hot side of the thermomechanical cooling unit 130, depending on whether the system 100 is performing air-heating or air-cooling functions. Thus, because the system 100 can utilize a single HTF circuit to provide thermal power for both air-heating and air-cooling functions, it thereby reduces the mechanical complexity of the system 100.
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Generally, the system 100 includes multiple heat transfer devices that transfer thermal energy from the solar thermal array 102 to the TES unit 110, from the TES unit 110 to other components of the system 100, and from the LTF reservoir to other components of the system 100 based on signals received from the control unit 160 or based on an independent control unit 160 particular to a heat transfer device. More specifically, the system 100 can include an array-to-storage heat transfer device 150, a storage-to-generator heat transfer device 152, a storage-to-air heat transfer device 140, a storage-to-water heat transfer device 142, a storage-to-cooler heat transfer device, and a cooler-to-sink heat transfer device 156 each of which is described in further detail below.
In various implementations, the system 100 can include heat transfer devices. Each heat transfer device can include multiple components including: a set of fluid circuits (e.g., HTF circuits, LTF circuits, water circuits, air circuits) configured to transfer a working fluid through a set of heat exchange interfaces (hereinafter “heat exchangers”). Each fluid circuit may include a set of variable speed or single speed pumps configured to control the flow rate of the working fluid through the fluid circuit. Additionally or alternatively, a heat transfer device can include a heat pump or both a heat pump and a heat exchanger. The system can include heat transfer devices with components and circulating fluids selected based on the particular application (e.g., on the expected operating temperatures of the destination and source) and/or other operational constraints, such as the distance between the destination and source components of each heat transfer device. Additionally, the system 100 can include heat transfer devices housing transfer fluids selected based on the above-described operational conditions. For example, a heat transfer device can circuit fluid including HTF such as high-temperature oils (e.g., biphenyl-diphenyl oxide-based oils, silicon-based oils, mineral-based oils), LTF such as ethylene or propylene glycol and water mixtures, refrigerants, mineral or synthetic oils, and/or methanol- or ethanol-water mixtures. Furthermore, the system 100 can include heat transfer devices configured for binary or variable-speed operation. For example, a binary heat transfer device is operable in an “on” state and an “off”′ state, while for a variable-speed heat transfer device, the system 100 can modulate the heat transfer rate of the heat transfer device via control signals from the control unit 160.
Generally, the system 100 includes an array-to-storage heat transfer device 150 configured to transfer heat from the solar thermal array 102 to the TES unit 110. More specifically, the array-to-storage heat transfer device 150 is configured to transfer heat between the array HTF and the storage HTF. Thus, the array-to-storage heat transfer device 150 is the means by which thermal energy is delivered to the system 100 via the solar thermal array 102.
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Generally, the system 100 includes a storage-to-generator heat transfer device 152 configured to transfer heat between the TES unit 110 and the generator unit 120. More specifically, the storage-to-generator heat transfer device 152 transfers heat between the TES HTF and the generator source. Thus, the system 100, via the operation of the storage-to-generator heat transfer device 152, can utilize stored thermal energy to deliver thermal power to the generator, thereby providing electrical power to the system 100 itself and to the structure.
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Generally, the system 100 includes a storage-to-air heat transfer device 140 configured to transfer heat from the TES unit 110 to the interior air of the structure. More specifically, the storage-to-air heat transfer device 140 can transfer heat from the TES HTF to a ventilation- or hydronic-based air-heating subsystem 300 as described above, which can then deliver heat to the interior air of the structure. Alternatively, the storage-to-air heat transfer device 140 can transfer heat to both the air-heating subsystem 300 and the air-cooling subsystem 500 via a combined storage-to-air heat transfer device 140. Thus, the system 100, via operation of the storage-to-air heat transfer device 140, can transfer stored thermal energy to heat and/or cool the interior air of the structure.
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Additionally or alternatively, the system 100 can include a single storage-to-water heat transfer device 142 to heat the potable hot water supply for the structure or two storage-to-water heat transfer device 142s, including a storage-to-hot-water heat transfer device and a storage-to-cold-water heat transfer device. Thus, the system 100 can effectively prevent freezing temperatures from occurring within the cold-water supply for the structure in colder climates.
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Generally, the system 100 relies in part on temperature measurements of various working fluids at various positions within the system 100 to adjust fluid flow rates within various fluid circuits. More specifically, the system 100 can include a combination of temperature measurement devices such as digital thermometers, thermocouples, thermistors, infrared thermometers, and/or any other type of temperature measurement device. The system includes a temperature measurement device at the source and/or destination of each heat transfer device. Additionally, the system 100 can include temperature measurement devices at critical points within the solar thermal array 102, the TES unit 110, and the generator unit 120 to regulate potential overheating events. Thus, via a set of temperature measurement devices, the system 100 can monitor the status of various elements of the system 100 such that the system 100 can be efficiently controlled to deliver thermal power appropriately to the generator unit 120 and elements of the structure.
In one implementation, the TES unit 110 includes a set of temperature measurement devices to determine the current state-of-charge of the TES unit 110 and the temperature for each stratum for a stratified TES unit 110. More specifically, the TES unit 110 can include an output temperature measurement device for each output stratum in the set of output strata of the stratified TES unit 110 and an input temperature measurement device for each input stratum in the set of input strata. Thus, the system 100 can utilize the set of output temperature measurement devices and the set of input temperature measurement devices within the TES unit 110 to operate the output valve array 170 and the input valve array 190 respectively.
Generally, the system 100 can include one or more thermal relief circuits to prevent various components of the system 100 from overheating during prolonged high solar intensity. More specifically, the system 100 can include an array thermal relief circuit that circulates the array HTF through a non-insulating environment to dissipate heat to the environment. Thus, the system 100 can operate the thermal relief circuit when thermal loads of the system 100 are satisfied by the solar thermal array 102, and the TES unit 110 is fully charged.
Generally, the system 100 includes a control unit 160 configured to operate the heat transfer devices to distribute thermal power throughout the system 100 by executing the methods S100, S200, S300, S400, and S500. In one implementation, the control unit 160 is an electrically powered computational device or set of computational devices (e.g., a central controller communicating with a set of microcontrollers) configured to receive and transmit digital and/or analog signals to various actuators within the system 100, such as motors, actuators, switches, etc., thereby modulating the flow of various working fluids within the heat transfer devices of the system 100. Additionally or alternatively, the control unit 160 can include digital or analog PID controllers and/or passive devices to regulate the flow of thermal energy through the system 100. Thus, the control unit 160 enables the intended operation of the system 100.
The control unit 160 simultaneously executes multiple control functions for the system 100, such as heating the interior air of the structure (air-heating operation), heating one or more water reservoirs of the structure (water-heating operation), and delivering an operative thermal load to the generator source to provide electrical power to the system 100 (generator operation), throttling various functions of the system 100 in cases of insufficient thermal power from both TES storage and the solar thermal array 102 (load reduction protocol), and/or drawing from or discharging electrical energy from the grid (in grid-tied variants). Each of these functions is described in further detail below.
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The control unit 160 can calculate a current electrical load for the generator unit 120 based on a sum of a current generator operative load, a current plug load for the structure, a current air-heating load for the storage-to-air heat transfer device 140, and a current water-heating load for the storage-to-water heat transfer device 142 in Step S110. More specifically, the control unit 160 can calculate the current air-heating or air-cooling load for the storage-to-air or storage-to-cooler heat transfer device based on a current air temperature and a current air set temperature for the structure; and calculate the current water-heating load for the storage-to-water heat transfer device 142 based on a current hot water temperature and a current hot water set temperature. The control unit 160 can execute a control loop algorithm including but not limited to PID control algorithms, look-up tables, etc., to calculate the thermal load for the air-heating or air-cooling and water-heating operations and correspondingly the electrical loads demanded by the storage-to-air or storage-to-cooler and storage-to-water heat transfer device 142 to deliver the calculated thermal loads to the air and water of the structure. The control methods corresponding to other functions of the system 100 (S300, S400, and S500) are further described below.
In implementations of the system 100 including a thermomechanical cooling unit 130, the control unit 160 can: calculate the thermal load for both the hot side and the cold side of the thermomechanical cooling unit 130 based on the current temperature of the interior air of the structure and the current set temperature; and calculate the air-cooling load by summing the electrical load from the storage-to-cooler heat transfer device and from the cooler-to-sink heat transfer device corresponding to thermal load for the thermomechanical cooling unit 130. More specifically, the control unit 160 can in addition to the above described Steps of the method S100: calculate a current air-cooling load of the thermomechanical cooling unit 130, the storage-to-cooler heat transfer device, and the cooler-to-sink heat transfer device 156; set the current air-heating load to zero; and operate the storage-to-cooler heat transfer device, the cooler-to-sink heat transfer device 156, and the thermomechanical cooling unit 130 in accordance with the current air-cooling load.
In particular, control unit 160 can also track the current electrical loads of the system 100 and structure including the generator operative load, the air-heating electrical load, the air-cooling electrical load, the water-heating electrical load, and/or the plug load for the structure utilizing electrical meters or other standard electrical metering equipment configured to measure current drawn by an operative electrical circuit, an air-heating electrical circuit, an air-cooling electrical circuit, a water-heating electrical circuit, and/or a structural electrical circuit respectively.
Generally, the operative electrical circuit is configured to electrically power the control unit 160, the generator unit 120, the TES unit 110, the solar thermal array 102, the storage-to-generator heat transfer device 152, the array-to-storage heat transfer device 150, the set of array-to-storage input valves 200 of the input valve array 190, the set of generator-to-storage input valves 192 of the input valve array 190, the set of storage-to-generator output valves 174 of the output valve array 170 and/or any other operatively critical components of the system 100. Thus, by maintaining power to the operative electrical circuit, the system 100 ensures control signals and power to the system 100 are isolated from the other electrical circuits and can therefore be preserved during execution of any load reduction protocol.
Generally, the air-heating electrical circuit is configured to supply electrical power from the generator to the storage-to-air heat transfer device 140, the set of storage-to-air output valves 175 of the output valve array 170, the set of air-to-storage input valves 193 of the input valve array 190 and/or any component of the air-heating subsystem 300. The air-cooling electrical circuit is configured to supply electrical power to the storage-to-cooler heat transfer device the cooler-to-sink heat transfer device 156, electrically powered components of the thermomechanical cooler, storage-to-cooler output valves 177 of the output valve array 170, cooler-to-storage input valves 195 of the input valve array 190, the heat sink refrigeration unit 108, or the exterior air cooling circuit 109 and/or any other component of the air-cooling subsystem 500. In implementations in which the air-heating subsystem 300 and air-cooling subsystem 500s are combined within the air-conditioning subsystem, the system 100 can include an air conditioning electrical circuit configured to supply power to the aforementioned components of the air-heating subsystem 300, the aforementioned components of the air-cooling subsystem 500, and/or any additional components of the air conditioning subsystem. Thus, via an electrical meter electrically coupled to the air-heating electrical circuit, the air-cooling electrical circuit, and/or the air conditioning electrical circuit, the control unit 160 can monitor the current air-heating load or the current air-cooling load depending on whether the system 100 is in an air-heating or air-cooling operational mode.
Generally, the water-heating electrical circuit is configured to supply electrical power to the storage-to-water heat transfer device 142, the set of storage-to-water output valves 176s of the output valve array, the set of water-to-storage input valves 194 of the input valve array 190, and/or any other component of the water-heating subsystem 400. Thus, via an electrical meter electrically coupled to the water-heating electrical circuit, the control unit 160 can monitor the current water-heating electrical load.
Generally, the structural electrical circuit is configured to supply electrical power for electrical devices of the structure (e.g., lighting, appliances, devices electrically coupled via wall outlets). In one implementation, the system 100 includes multiple structural electrical circuits (e.g., a kitchen circuit, a living room circuit), thereby enabling the control unit 160 to progressively throttle the plug loads to reduce the thermal load for the generator unit.
, Thus, the control unit 160 can calculate the total electrical load by summing the electrical load measured by the metering devices of for each electrical circuit in a set of electrical circuits including: the operative electrical circuit, the air-heating electrical circuit, the air-cooling electrical circuit, the water-heating electrical circuit, and/or the structural electrical circuit.
Upon calculating the total electrical load on the generator unit 120, the control unit 160 can calculate a current thermal load for the generator unit 120 based on the current electrical load in Step S120. More specifically, the control unit 160 can utilize a calibrated lookup table or physical model to calculate the thermal load that will satisfy the total electrical load calculated in Step S110. Additionally or alternatively, the control unit 160 can execute a PID control algorithm or any other control algorithm to supply thermal power based on the current electrical load. In one implementation, the control unit 160 can utilize predictive machine learning algorithms to anticipate periods of higher electrical load on the generator unit 120 and proactively increase the thermal load transmitted to the generator.
The control unit 160 can then calculate a current storage-to-generator heat transfer rate sufficient to supply the current thermal load to the generator in Step S130. More specifically, the control unit 160 can utilize a calibrated lookup table or physical model to identify a rate of heat transfer from the TES unit 110 that supplies the current thermal load to the generator while accounting for thermal energy lost during transfer. The control unit 160 can further transform this heat transfer rate to a pump flow setting of a storage-to-generator variable speed pump within the storage-to-generator heat transfer device 152.
The control unit 160 can also calculate a current target output temperature for the high-temperature fluid based on a set of generator operative parameters in Step S140. The set of generator operative parameters can include but are not limited to: generator process fluid temperatures (e.g., an inlet temperature of hot side fluid, an inlet temperature of cold side fluid, a target inlet temperature of hot side fluid, a target inlet temperature of cold side fluid), heat transfer coefficients between the hot side and the storage-to-generator heat transfer device 152, heat transfer coefficients between the cold side and exterior cooling circuit, thermal properties of the generator process fluid (e.g., specific heat capacity, density over a range of operational temperatures, viscosity), evaporation and condensation temperatures if applicable, external operating conditions such as ambient temperature and environment heat gains or losses, and/or cooling duty. For example the control unit 160 can calculate a current target output temperature based on a most efficient temperature for the storage-to-generator heat transfer device 152 that maintains a sufficient gradient across the hot and cold sides of the generator unit 120.
Upon calculating a current target output temperature, the control unit 160 can actuate the output valve array 170 to output the high-temperature fluid at the current target output temperature in Step S150. More specifically, the control unit 160 can: select a hotter output stratum and a colder stratum from the set of output strata exhibiting hotter and colder temperatures than the current target output temperature respectively; and actuate a hotter output valve corresponding to the hotter output stratum and a colder output valve corresponding to the colder output stratum to effect the current target output temperature in the storage-to-generator HTF circuit.
In one implementation, the control unit 160 can operate the output valve array 170 to deliver the thermal load to the generator source within a range of target operating temperatures for the generator source. The control unit 160 can utilize a lookup table or a physical model of the system 100 to estimate thermal losses incurred during transmission of the thermal load via the storage-to-generator heat transfer device 152 to select a target output temperature for the output HTF. The control unit 160 can then operate the output valve array 170 to achieve the target output temperature by selecting a first output stratum characterized by a first temperature greater than the target output temperature, selecting a second output stratum characterized by a temperature less than the target output temperature, and mixing HTF from the first output stratum and the second output stratum according to a target ratio to generate an output HTF at the target temperature.
In addition to modulating the transfer of thermal power to the generator, the control unit 160 can transmit and receive control signals to the generator unit 120 to modulate power output, initiate a startup sequence, or initiate a shutdown sequence.
The control unit 160 can operate the storage-to-generator heat transfer device 152 according to the current storage-to-generator heat transfer rate in Step S160. More specifically, the control unit 160 can adjust the flow rate of the storage-to-generator heat transfer device 152 (e.g., by adjusting the setting of a variable speed pump within the storage-to-generator heat transfer device 152 such that the current thermal load is provided to the generator based on the target output temperature).
Upon providing the current thermal load to the generator, the control unit 160 can operate the air-heating subsystem 300 in accordance with the current air-heating load in step S170. More specifically, the control unit 160 can distribute electrical power from the generator unit 120 to the storage-to-air heat transfer device 140. Additionally, the control unit 160 can operate water-heating subsystem 400 in accordance with the current water-heating load in Step S180. Similarly, the control unit 160 can distribute electrical power from the generator unit 120 to the storage-to-water heat transfer device 142. In some implementations, the control unit 160 can also operate the air-cooling subsystem 500 in accordance with the current air-cooling load. More specifically, the control unit 160 can operate the cooler-to-sink heat transfer device 156, and/or the heat sink refrigeration unit 108 in accordance with the air-cooling load.
In instances in which, the control unit 160 is configured to operate multiple components within a subsystem in accordance with an electrical load, the control unit 160 can distribute/coordinate power distribution between the components of the subsystem.
In one variant, shown in
In one example, the control unit 160 executes a load reduction protocol that prioritizes the electrical load attributable to the operation of the generator, over the plug load of the structure, over the electrical load attributable to the air-heating or air-cooling operation of the system 100, over the electrical load attributable to the water-heating operation of the system 100. Thus, the control unit 160 can selectively reduce the electrical load demanded of the generator unit 120 by modulating or shutting down water-heating operations then air-heating or air-cooling operations of the system 100 until the combined electrical load of the system 100 and structure can be met by the generator unit 120.
In yet another implementation, the control unit 160 can also operate circuit breakers within the electrical panel of the structure to modulate plug loads of the structure if the air-heating operation and water-heating operation have already been shut down and the electrical load remains too high to be met by the generator unit 120 given the available thermal power from the TES unit 110.
In another implementation, the control unit 160 can begin to throttle operational loads based on expected solar intensity to the solar thermal array 102 and/or a state-of-charge of the TES unit 110. Thus, the control unit 160 can manage instant electrical loads and longer-term energy consumption of the system 100 and structure.
In yet another implementation, the control unit 160 can receive a user-configured or user-defined load reduction protocol that specifies an order of priority between various functions of the system 100 along with temperature limits for each function. For example, a user-defined load reduction protocol can include a minimum temperature for the interior air of the structure, a maximum temperature for the interior air of the structure, and a minimum hot water temperature. Additionally, this example protocol could specify that air heating and cooling be prioritized above water heating. Therefore, in a low-state-of-charge or heat transfer capacity scenario, the control unit 160 would first throttle the water heating before turning off the water heating operation, then the control unit 160 would reduce electrical power to the air-heating or air-cooling operation, whichever is currently active until the minimum or maximum temperature is reached. At that point, the control unit 160 can throttle plug loads and to maintain the minimum or maximum temperature within the structure.
In another variant, shown in
Additionally, in instances of high solar incidence (i.e., greater than a threshold solar incidence or greater than a threshold expected solar incidence) and high state-of-charge of the TES unit 110 (i.e., greater than a threshold state-of-charge), the control unit 160 can increase the output of the generator unit 120 (e.g., by increasing the thermal load applied to the generator source) and discharge surplus electrical power produced by the generator unit 120 to the grid. More specifically, the control unit 160 can, in response to a current thermal energy storage state-of-charge exceeding a threshold state-of-charge: operating the storage-to-generator heat transfer device 152 at the current storage-to-generator heat transfer capacity in Step S296; and discharging excess electrical energy produced by the generator unit 120 to the grid in Step S298.
As shown in
Generally, heat exchange parameters can include the thermal conductivity and other properties of heat exchanging fluids (e.g., HTF, LTF, water, air), heat transfer coefficients (e.g., convective, conductive, radiative, combined), surface area, flow configuration and exchanger geometries, or any other parameter that may affect heat transfer through a heat transfer device.
As shown in
Additionally, the air-cooling method S500 also includes Steps for maintaining the thermal capacity of the heat sink subsystem 104 to absorb heat from the cold side of the thermomechanical cooling unit 130. More specifically, the air cooling method S500 includes, in response to a threshold temperature of the low temperature fluid reservoir exceeding a current temperature of the LTF reservoir: operating the heat sink refrigeration unit 108 to lower the temperature of the low temperature fluid reservoir below the threshold temperature of the low temperature fluid reservoir in Step S540. The control unit 160 can set the threshold temperature based on the specific heat capacity and mass of the LTF within the LTF reservoir and the expected cooling requirements over a subsequent time period. For example, the control unit 160 can utilize local predictive weather data to “charge” the LTF reservoir to a lower temperature (e.g., 0° C.). Thus, by utilizing a high capacity LTF reservoir (e.g., 0.5 gallons per square foot) the system 100 can include a much smaller and more efficient heat sink refrigeration unit 108.
In one implementation, the control unit 160 can operate the heat sink refrigeration unit 108 to lower the temperature of the LTF reservoir while heating the structure via the air-heating method S300 in preparation for future cooling loads. In this implementation, the control unit 160 can measure non-zero air-heating and air-cooling loads simultaneously and can operate the generator to satisfy these loads.
Generally, the set of thermomechanical cooling unit parameters can include but are not limited to: cooler process fluid temperatures (e.g., an inlet temperature of hot side fluid, an inlet temperature of cold side fluid, a target inlet temperature of hot side fluid, a target inlet temperature of cold side fluid), heat transfer coefficients between the hot side and the storage-to-cooler heat transfer device, heat transfer coefficients between the cold side and the cooler-to-sink heat transfer device 156, thermal properties of the cooler process fluid (e.g., specific heat capacity, density over a range of operational temperatures, viscosity), evaporation and condensation temperatures if applicable, external operating conditions such as ambient temperature and environment heat gains or losses, and/or cooling duty.
In one implementation, the control unit 160 selects a target output temperature for each HTF circuit as an efficiency maximizing safe temperature for the HTF circuit. More specifically, the control unit 160 can calculate this target output temperature based on physical model or data-based models of each heat transfer device.
Generally, the control unit 160 can execute any control algorithm to execute air-heating and air-cooling operations including but not limited to: on-off control, PID control, physical modelling/predictive control, adaptive control algorithms, demand-control ventilation, supervisory control and data acquisition, and/or machine-leaning or AI-based control algorithms.
Generally, the control unit 160 can heat one or more water reservoirs (e.g., a hot and a cold water reservoir) of the structure via the array-to-water heat transfer device and/or the storage-to-water heat transfer device 142. More specifically, the control unit 160 can: access a current hot water set temperature for the structure, a current temperature of potable hot water supply for the structure, and a set of storage-to-water heat exchange parameters in Step S410; calculate a target storage-to-water heat transfer rate based on the current hot water set temperature for the structure, the current temperature of the potable hot water supply for the structure, and the set of storage-to-water heat exchange parameters in Step S420; and operate the output valve array 170 to output a high-temperature fluid at a target storage-to-water temperature effecting the target storage-to-water heat transfer rate between the high-temperature fluid and the potable hot water supply in Step S430. In particular, as described above with respect to the air-heating and cooling operations, the control unit 160 can execute any control algorithm to execute water-heating operations including but not limited to: on-off control, PID control, physical modelling/predictive control, adaptive control algorithms, demand-control ventilation, supervisory control and data acquisition, and/or machine-leaning or AI-based control algorithms.
This application claims the benefit of U.S. Provisional Application No. 63/624,210, filed on 23 Jan. 2024, which is incorporated in its entirety by this reference.
| Number | Date | Country | |
|---|---|---|---|
| 63624210 | Jan 2024 | US |
