Patent Application
20170356695
Heating, ventilation, and air conditioning (HVAC) systems are used extensively in both buildings and vehicles to control climate. Most common HVAC systems utilize compression and expansion of a cycled refrigerant using a compressor and pump. However, this convenience can be extremely energy consumptive in both buildings and vehicles. Other HVAC systems include evaporative coolers, heat pumps, and the like. However, each system has limitations in terms of performance and/or cost. Hence, there is a need for improved HVAC systems that can adequately control climate while reducing the energy consumption required to operate the system.
A climate control system can include a thermal battery and a heat exchange module. The thermal battery can include at least one heating bed and at least one cooling bed that are fluidly connected to one another. The heating bed includes a compacted metal salt and the cooling bed includes a volatile polar compound, which form a reversible thermochemical reaction system when fluidly connected. The battery can also include a flow control mechanism adapted to selectively allow fluid to flow between the heating bed and the cooling bed. The heat exchange module can be thermally associated with at least one heating bed and at least one cooling bed and can be adapted to condition an inlet air.
A method of controlling climate within an enclosure including contemporaneously generating a heating effect and a cooling effect from a reversible thermochemical reaction and selectively directing thermal flows from the reversible thermochemical reaction to increase or decrease a temperature within the enclosure. The reversible thermochemical reaction can have an endothermic reaction and a complimentary exothermic reaction that are thermally remote from one another, yet fluidly connected via a selectively controllable flow control.
There has thus been outlined, rather broadly, the more important features of the invention so that the detailed description thereof that follows may be better understood, and so that the present contribution to the art may be better appreciated. Other features of the present invention will become clearer from the following detailed description of the invention, taken with the accompanying drawings and claims, or may be learned by the practice of the invention.
These drawings are provided to illustrate various aspects of the invention and are not intended to be limiting of the scope in terms of dimensions, materials, configurations, arrangements or proportions unless otherwise limited by the claims.
While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the present invention. Thus, the following more detailed description of the embodiments of the present invention is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the present invention, to set forth the best mode of operation of the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the present invention is to be defined solely by the appended claims.
Definitions
In describing and claiming the present invention, the following terminology will be used.
The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a particle” includes reference to one or more of such materials and reference to “subjecting” refers to one or more such steps.
As used herein with respect to an identified property or circumstance, “substantially” refers to a degree of deviation that is sufficiently small so as to not measurably detract from the identified property or circumstance. The exact degree of deviation allowable may in some cases depend on the specific context.
As used herein, “adjacent” refers to the proximity of two structures or elements. Particularly, elements that are identified as being “adjacent” may be either abutting or connected. Such elements may also be near or close to each other without necessarily contacting each other. The exact degree of proximity may in some cases depend on the specific context.
As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary.
Concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of about 1 to about 4.5 should be interpreted to include not only the explicitly recited limits of 1 to about 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than about 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described.
Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. Means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; and b) a corresponding function is expressly recited. The structure, material or acts that support the means-plus function are expressly recited in the description herein. Accordingly, the scope of the invention should be determined solely by the appended claims and their legal equivalents, rather than by the descriptions and examples given herein.
Heating, ventilation, and air conditioning (HVAC) systems are important in controlling the ambient temperature of both buildings and vehicles. However, operation of HVAC systems in both buildings and vehicles can be highly energy-consumptive. This can be especially evident in electric vehicles and long-haul tractor-trailers.
Current electric vehicles use resistive heating and an electrically driven air conditioning compressor to provide cabin heating and cooling, respectively. The energy consumption to operate this type of HVAC system in electric vehicles can, in many cases, reduce the driving range up to 40%.
In long-haul tractor trailers and other vehicles with internal combustion engines, cabin heating is provided from excess engine heat, consuming no extra energy from the engine. However, cabin cooling is provided by an air conditioning compressor powered by the engine, consuming only a small portion of the energy from the engine. However, the engine must be running to operate such an HVAC system, requiring continuous combustion of fuel. On long trips, these long-haul drivers occasionally need to pull off the road to rest. However, as described previously, the drivers must leave the engine running to operate the HVAC system and achieve a comfortable climate. This can be very costly to the driver and the environment. Hence, there is a need for improved heating and cooling systems that are efficient but less energy consumptive.
Thermal batteries can be used in HVAC systems as an alternative to conventional HVAC systems that are powered electrically or by the combustion of fuels. These batteries can store energy from a variety of sources and release the energy on demand in a controlled manner as thermal energy.
Additionally, thermal batteries are generally very portable and could be used in a variety of settings including electric vehicles, long-haul tractor-trailers, camping trailers, tents, buildings, rooms, and other suitable areas. The portability of thermal batteries can be advantageous when conditions are such that no HVAC system is necessary, and, therefore, the thermal battery can be stored remotely until it is needed.
Thermal batteries can be used in stand-alone HVAC systems or in a supplemental HVAC system. For example, a thermal battery can be used in an electric vehicle as the sole HVAC system so that the electric battery can be preserved to extend the driving range of the vehicle. In another example, a thermal battery can be used to precondition the cabin of the electric vehicle to an appropriate temperature prior to operating the electrically powered HVAC system of the vehicle, thus reducing the energy consumption from the electric battery. In another example, a thermal battery can be used to replace either the heating or cooling function of a traditional HVAC system. In another example, a thermal battery can be used in addition to a traditional HVAC system to provide supplementary heating and/or cooling.
Accordingly, a climate control system is described herein that includes a thermal battery and a heat exchange module.
When the flow control mechanism 130, such as a conduit valve, is opened to allow fluid flow between the heating bed 110 and the cooling bed 120, a heating effect and a cooling effect are contemporaneously produced, respectively. This occurs as a result of the contemporaneous exothermic adsorption/absorption of a volatile polar compound from the cooling bed 120 onto/into the compacted metal salt within the heating bed 110, and the corresponding endothermic evaporation of the volatile polar compound within the cooling bed 120.
When a cooling effect is desirable, cooled inlet air conditioned by the cooling bed 120 can be directed toward a desired enclosure and the heated inlet air conditioned by the heating bed 110 can be vented to an area outside the desired temperature-controlled enclosure. Conversely, when a heating effect is desirable, heated inlet air conditioned by the heating bed 110 can be directed toward the desired enclosure and the cooled inlet air conditioned by the cooling bed 120 can be vented to an area outside the desired enclosure. The climate control system can be adapted to provide a heating or cooling effect to any number of enclosures, including a passenger compartment, such as an automobile cabin, a cargo container, a room, a building, a camping trailer, a tent, or any other suitable enclosure. When the thermal battery 100 of the climate control system needs to be recharged, the heating bed can be heated to drive the volatile polar compound away from the compacted metal salt and back toward the cooling bed. The flow control mechanism can then be closed to store the battery for later use or left open for immediate use.
More specifically, the embodiment illustrated in FIG. lA shows a thermal battery 100 in cooling mode. In this particular embodiment, the flow control mechanism 130 can be in an open position to allow fluid to flow between the heating bed 110 and the cooling bed 120. More specifically, a volatile polar compound from the cooling bed can flow to the heating bed to produce a simultaneous heating and cooling effect in the thermal battery. The fluid flow can be facilitated by a connecting conduit 140 or other suitable configuration which allows fluid flow from the cooling bed to the heating bed. The air, such as an outside air, that is cooled by the cooling bed can be directed toward an automobile cabin or other desired area. The air that is heated by the heating bed can be directed away from the automobile cabin or other desired area, such as to an exterior location.
The embodiment illustrated in
The embodiment illustrated in
The desorption of the polar volatile compound from the compacted metal salt can be stepwise. In one example, where the polar volatile compound is ammonia and the compacted metal salt is MgCl2, the desorption can occur as follows:
MgCl2(NH3)6=MgCl2(NH3)2 +4NH3 (main step)
MgCl2(NH3)2=MgCl2(NH3)+NH3 (minor step 1)
MgCl2(NH3)=MgCl2+NH3 (minor step 2)
In one aspect, when the heating bed is heated, the pressure within the heating bed can increase to a level that exceeds the pressure in the cooling bed, thus facilitating the movement of the polar volatile compound back to the cooling bed. Here, the flow control mechanism 130 remains open to allow fluid to flow between the two beds. The condensation of the heated polar volatile compound in the cooling bed can be facilitated by directing heated air away from the cooling bed to an external environment or other suitable location. The climate control system can include a recharging module or mechanism that is controllable by electronic controls on the system or via a remote device (not shown).
The embodiment illustrated in
As previously described, each cooling bed or cell of the thermal battery can include a volatile polar compound. A suitable volatile polar compound generally can be a compound that endothermically evaporates at standard temperature and pressure, thus providing a cooling effect. A variety of suitable volatile polar compounds can be used. Non-limiting examples of suitable volatile polar compounds can include ammonia, water, methanol, ethanol, 1-propanol, 2-propanol, acetone, acetonitrile, and combinations thereof. In one aspect, ammonia can be the volatile polar compound.
In one alternative aspect, each heating bed or cell of the thermal battery can include a compacted metal salt pellet or disc. A variety of compacted metal salts can be used in the current technology. In one aspect, the compacted metal salt is a metal chloride such as MgCl2, MnCl2, CaCl2, NiCl2, and combinations thereof. In another aspect, the compacted metal salt can be an ammonia complex or mixture thereof, such as MgCl2(NH3)6, MnCl2(NH3)6, CaCl2(NH3)8, NiCl2(NH3)6, and combinations thereof. The previously mentioned metal salts are only examples of metal chloride salts that can be used with the current technology and are not intended to be exhaustive. There are many other metal chloride salts that can be used separately or in combinations, including in combination with the previously mentioned metal chloride salts. Such metal chloride salts can include SrCl2, ZnCl2, CoCl2, FeCl2, and other metal chlorides and mixtures thereof. Metal salts other than metal chlorides can also be used, such as metal bromide salts, metal iodide salts, metal perchlorate salts, metal nitrate salts, metal sulfate salts, metal phosphate salts, and other suitable metal salts and mixtures thereof that are capable of exothermically adsorbing or absorbing the corresponding polar volatile compound. The heating bed produces a heating effect via an exothermic adsorption or absorption of the volatile polar compound onto or into the compacted metal salt. Table 1 includes some examples of relevant temperatures and pressures that can be considered when selecting an appropriate compacted metal salt.
The compacted pellets or discs of the metal salt can be prepared using a suitable pellet press, such as an electric hydraulic pellet press, or other suitable method to compact the metal salts. In one aspect, the compacted pellet or disc from the metal salt can be prepared after the metal salt has already formed a complex with the volatile polar compound, such as with MgCl2(NH3)6, MnCl2(NH3)6, CaCl2(NH3)8, and NiCl2(NH3)6. Additionally, the compacted metal salt can include other additives such as expandable graphite. For example, a metal salt, or ammonia-complexed metal salt, can be mixed with from 10 wt % to 30 wt % expandable graphite and hydraulically or otherwise pressed into a compacted pellet or disc to be included in the heating bed. In one aspect, the metal salt or ammonia-complexed metal salt can be mixed with from 15 wt % to 25 wt % expandable graphite. In one aspect, the metal salt or ammonia-complexed metal salt can be mixed with from 18 wt % to 22 wt % expandable graphite, or about 20 wt %.
Additionally, the compacted metal salt can have a relatively low porosity. Desirable ranges of porosity can typically be from 0% to 40% , 0% to 30% , or from 0% to 20%. In a further aspect, the porosity of the compacted metal salt can be 10% or less, 8% or less, 5% or less, 3% or less, or 1% or less. In some cases, compacted metal salts with lower porosities can absorb ammonia, or other volatile polar compounds, more quickly than those with higher porosities. This is contrary to the previous understanding that the permeation of the metal salt structure was the rate-limiting step of absorption and that a higher porosity was preferable.
The compacted metal salt pellets can be packed in the heating bed at a packing density between 60 and 99%. In one aspect, the packing density can be between 70 and 99%. In one aspect the packing density can be between 80 and 99%. In one aspect, the packing density can be between 90 and 99%. In one aspect, the packing density can be between 92 and 98%. In one aspect, the compacted metal salt can be packed in the heating bed at a packing density of about 95%.
Alternatively, the metal salt can be dissolved in a solvent such as water, injected into the heating bed, dried, and then exposed to the polar gas for subsequent absorption. This can be particularly useful if open cell metal foams are used for enhancing the heated bed effective thermal conductivity.
Because the heat transfer of the compacted metal salt pellets or discs can be the rate limiting step for the overall process of absorption and desorption of the polar volatile compound, it can be desirable to construct a heating bed that can enable excellent heat transfer between the pellets and a heat transfer source, both for recharging and thermal effects.
As previously mentioned, the heating bed(s) and cooling bed(s) can be made from a variety of suitable materials. For example, the cooling bed can be made of stainless steel, aluminum, or other suitable material to hold the polar volatile compound. The heating bed can be made of stainless steel, nickel-plated aluminum, or other suitable material. In one aspect, the cooling bed can be enclosed or enclosable, thus forming a cooling enclosure as part of a closed, reversible system. Additionally, the heating bed can also be enclosed or enclosable, thus forming a heating enclosure as a part of a closed, reversible system.
The heating bed(s) and cooling bed(s) can be connected by at least one connecting conduit and the flow control mechanism can include at least one conduit valve within the connect conduit. The conduit valve can be selectively adjustable to control fluid flow rates between the heating bed and the cooling bed. Adjustment of the flow rates can control how long the thermal battery will last and the degree of cooling and heating effects achieved by the thermal battery. The connecting conduit can form a closed system with the at least one heating bed and the at least one cooling bed. The connecting conduit or conduit system can be made of suitable gas-tight tubing and associated connections and fittings. Appropriate tubing and fittings can be made of stainless steel, brass, copper, aluminum, nickel-plated aluminum, nickel-plated copper, or other suitable tubing. The conduit valve can comprise a suitable pneumatic valve, such as a solenoid valve. The valve can be adapted to have only substantially open and substantially closed positions, or it can be adapted to have a plurality of positions to allow a plurality of fluid flow rates between the cooling bed and the heating bed.
One embodiment of the climate control system is illustrated by
More specifically, the climate control system 300 can include a heat exchange module, generally denoted as 350, which is thermally associated with the heating bed(s) 310 and the cooling bed(s) 320 of the thermal battery, and can be adapted to condition an inlet air. The heat exchange module 350 can be adapted to circulate at least one heat transfer fluid between at least one of the heating bed 310 and the cooling bed 320. The heating bed and the cooling bed can be fluidly connected to one another by a variety of suitable structures. In one aspect, the heating bed and the cooling bed can be fluidly connected via at least one connecting conduit 340. The connecting conduit can include a suitable flow control mechanism, such as solenoid valve 330. A heating wire or other heat exchanger 360 can be thermally associated with the heating bed 310 for recharging of the thermal battery. In one embodiment, the heat exchange module includes a single loop that circulates a heat transfer fluid between a heat exchanger and both the heating bed and the cooling bed (not shown). In one aspect, the heat transfer fluid can be selectively directed to interact with either the heating bed or the cooling bed, or, alternatively, directed to interact with the heating and cooling beds at different times, to provide a heating effect or a cooling effect (not shown). In another embodiment, the heat exchange module includes separate loops that circulate a first heat transfer fluid between a first heat exchanger 358 and the heating bed 310 and a second heat transfer fluid between a second heat exchanger 359 and the cooling bed 320. The heat exchangers can also include at least one pump, such as 355a and 355b. The pumps can be energy efficient or low energy pumps. In one example, the pumps can require less than 0.24 kW for a thermal battery with a cooling/heating capacity of 2.5 kWh. Thus the energy penalty of using indirect heat transfer via the heat exchange module can be small.
The first and second heat transfer fluids can be the same or they can be two separate fluids. A variety of suitable heat transfer fluids can be used. In one aspect, the heat transfer fluid can include a water/ethylene glycol mixture, such as about 60% by volume of ethylene glycol in water. In one aspect, the heat transfer fluid can include a mixture of diphenylethane and alkylated aromatics, such as DOWTHERM Q from Dow Chemical Company. In one aspect, the heat transfer fluid can include a pentafluoropropane, such as R245, and/or a tetrafluoroethane, such as R134a, which can be used for either hot or cold side conditioning. For example, the liquid heat transfer fluid can be pumped to an air-heated evaporator for air conditioning or to an external air-heated evaporator for heating applications. Similarly, a terphenyl heat transfer fluid, such as THERMINOL 66, can be used to transfer heat to and from the heating bed to condition an inlet air. In another example, this fluid can transfer heat from a truck exhaust stream to recharge the thermal battery or to a third heat exchanger that heats and vaporizes R245 or R134a.
The heat exchange module 350 can also include a conditioned air manifold 352 adapted to direct conditioned air into an enclosure. Suitable enclosures can include a passenger compartment, such as an automobile cabin, and/or a cargo container, a room, a building, a camping trailer, a tent, or any other suitable enclosure. The conditioned air can be directed into an enclosure via at least one of convection and forced air by a blower, such as fans 357a and 357b. The conditioned air manifold 352 can also include at least one duct 354 in thermal communication with a heat transfer fluid. The duct 354 can be adapted to selectively adjust the conditioned inlet air to achieve a desired thermal effect within the enclosure. The duct can be adjusted with a valve, such as butterfly valve 351, or any other suitable mechanism to selectively propagate appropriately conditioned air to achieve a desired thermal effect. In one aspect, the duct 354 and valve can be adjusted to conduct inlet air conditioned by the heating bed 310 toward the enclosure. In one aspect, the duct and valve can be adjusted to conduct inlet air conditioned by the cooling bed 320 toward the enclosure. The duct and valve can be selectively adjusted to provide thermal flows from only the heating bed, only the cooling bed, or combinations of both to obtain the desired thermal effect. Additionally, the conditioned air manifold can include inlet/outlet connectors that connect to a ducting system already associated with the enclosure. In one aspect, the conditioned air manifold can have inlet/outlet connectors that allow the climate control system to be a plug-play system. Undesired thermal flows can optionally be directed to an area away from the target enclosure or enclosures. Additionally, at least one fan or other blower, such as fans 357a and 357b, can be associated with the duct 354 to adjust the rate at which the desired thermal effect is conducted through the duct toward the enclosure or desired area of the enclosure. Optionally, a fan can be used to adjust the rate at which undesired thermal flows are vented outside the enclosure. The conditioned air manifold can also include an outlet vent 356 adapted to direct the conditioned air into the enclosure.
As illustrated in the embodiment of
Power production can be provided through the incorporation of an organic Rankine cycle between the heating bed 410 and the cooling bed 420 via a secondary turbine loop. Conduits 442 and 443 a serve as heat exchangers to either evaporate a secondary turbine loop working fluid, or condense the working fluid, respectively. A liquid pump 450 is placed along the conduit between the cooling bed and the heating bed to circulate the working fluid through the secondary turbine loop. The secondary working fluid can be a high-pressure refrigerant which is vaporized in the heating bed 410. The high pressure vapor then enters the turbine 470 to propel the rotor assembly of the turbine 470 to produce electrical power which can be stored in a battery 472 or used to augment power to the vehicle wheels or other electrical systems. In one optional aspect, a turbine can be associated with connecting conduit 440, or another connecting conduit, so that the volatile polar compound can propel the rotary assembly of the turbine during recharging. A combination of both systems can be used. For example, the system can be used as a heating-cooling system, a power production system, or a hybrid system where both HVAC and power is produced.
Optionally, the third heat exchanger 462 can be used for both recharging and accelerating the endothermic evaporation of the volatile polar compound. In another example, a turbine can be operatively associated with at least one of the first and second heat exchangers in order to produce electrical power. For example, the third heat exchanger 462 can be thermally associated with the second heat exchanger (not shown). The second heat exchanger can be thermally associated with the cooling bed and can include a refrigerant. The second heat exchanger can also be exposed to the ambient air to condense the refrigerant. The third heat exchanger can add heat to the second heat exchanger and vaporize the refrigerant. The refrigerant can be directed toward a turbine that is operatively connected to the second heat exchanger. As the refrigerant travels towards a condenser, it can propel the rotary assembly of the turbine and produce electrical power. Optionally, a heat exchanger 464 can be used to introduce heat into heating bed 410. Suitable heat can be recovered from a heat source such as, but not limited to, engine heat, brakes, exhaust, and the like. Such heat recovery can be used to supplement power production by adding energy to the organic Rankine cycle described herein. The electrical power can be used to charge a storage battery 472, a set of batteries, power electric motors to propel a vehicle, and/or provide auxiliary short-term power to devices in a vehicle cabin. Thus, this electrical power can be used immediately or stored. Accordingly, a storage battery can be operatively connected to the turbine to store produced electricity.
As illustrated in the embodiment of
The controller module 580 can be operably connected to at least one of the flow control mechanism, such as an electrically actuated valve 530, and the conditioned air manifold (not shown). In one aspect, the controller module can include controls to enable power input for recharging, control recharging temperature, control an opening/closing/adjusting of the flow control mechanism, and the like. Additionally, the controller module 580 is adapted to communicate with the communication module 582 to control one or both of the reaction of the thermochemical reaction system and the flows of the conditioned air. Communication between the controller module 580 and the communication module 582 can be wireless or it can be facilitated by physical connection of wires, cables, or other suitable connection.
Remote control of the system can be advantageous for a variety of operations, such as preconditioning the target enclosure or enclosures with a desired thermal effect. For example, an electric vehicle that has been sitting in the sun can be preconditioned with a cooling effect by sending a wireless signal from a remote device to the thermal battery system to begin cooling the cabin of the electric vehicle. Not only does this precondition the cabin with a comfortable climate, but it will reduce the energy consumption of the electric battery to cool the cabin with the electrically powered HVAC of the vehicle.
In another embodiment, the climate control system can be a modular system. The modular system can have at least one pair of inlet and outlet connectors adapted to operably connect to a heat transfer system in a vehicle, room, or the like. In one aspect, the system can have two pairs of inlet and outlet connections, one pair for the heating bed and one pair for the cooling bed. The system can be easily connected and disconnected to the heat transfer system with any suitable connections such as quick-connect fittings, cam-lock fittings, and the like.
The modular system can have various numbers of heating and cooling beds. In one aspect, the modular system can be adapted to accommodate and fluidly connect with additional plug-and-play heating and cooling beds or thermal batteries. This can allow a user to achieve greater or more prolonged thermal effects from the climate control system, as desirable. In one aspect, the controller module of the climate control system can control and synchronize additional heating and cooling beds or thermal batteries that are connected to the system. For example, each heating bed, cooling bed, or thermal battery can be synchronized to operate and recharge at intervals that will allow continuous production of thermal effects with minimal to no down time. In one aspect, the controller module can instruct at least one group of heating and cooling beds to produce desired thermal effects while at least one group of heating and cooling beds are recharging. In one aspect, each of the assigned groups of heating and cooling beds or thermal batteries can be in various stages of recharging/discharging, each of which is controlled by the controller module. In one aspect, more than one heating bed can be fluidly connected to a single cooling bed. In one aspect, a single heating bed can be fluidly connected to more than one cooling bed. This can allow the modular system to accommodate different sizes and numbers of heating beds and cooling beds.
Additionally, each of the modular systems can be operably connected to or networked with additional modular systems. In one aspect, all of the connected modular systems can be controlled by a single, designated modular system. In another aspect, each modular system can be connected to a common main controller module.
In another embodiment, a method is disclosed for controlling climate in an enclosure. The method can include contemporaneously generating a heating effect and a cooling effect from a reversible thermochemical reaction and selectively directing thermal flows from the reversible thermochemical reaction to increase or decrease a temperature within the enclosure. The reversible thermochemical reaction can have an endothermic reaction and a complimentary exothermic reaction that are thermally remote from one another, yet fluidly connected via a selectively controllable flow control.
The endothermic reaction generates the cooling effect and the exothermic reaction generates the heating effect. The endothermic reaction can include evaporation of a polar volatile compound, such as ammonia, water, methanol, and other suitable alcohols, amines, and volatile polar compounds and combinations thereof. The exothermic reaction can include adsorption or absorption of the evaporated polar volatile compound onto or into a metal salt. The metal salt can be compacted into pellets or discs and the pellets or discs can be tightly packed together. In one aspect, the metal salt can be a metal chloride such as MgCl2, MnCl2, CaCl2, and NiCl2, or an ammonia complex or mixture thereof, such as MgCl2(NH3)6, MnCl2(NH3)6, CaCl2(NH3)8 and NiCl2(NH3)6. The previously mentioned metal salts are only examples of metal chloride salts that can be used with the current technology and are not intended to be exhaustive. There are many other metal chloride salts that can be used separately or in combinations, including combinations with the previously mentioned metal chloride salts. Such metal chloride salts can include SrCl2, ZnCl2, CoCl2, FeCl2, SnCl2, and other metal chlorides and mixtures thereof. Metal salts other than metal chlorides can also be used, such as metal bromide salts, metal iodide salts, metal perchlorate salts, metal nitrate salts, metal sulfate salts, metal phosphate salts, and other suitable metal salts and mixtures thereof that are capable of exothermically adsorbing or absorbing at least one volatile polar compound.
The selectively controllable flow control adjusts the degree of fluid interaction between the reactants of the reversible thermochemical reaction. The greater the interaction, the greater the heating and cooling effects will be, but the reaction will proceed to completion at a much greater rate, thus decreasing the effective time period for controlling climate within the enclosure. The lower the interaction between the reactants, the lower the heating and cooling effects will be, but the reaction will proceed to completion at a much slower rate, thus prolonging the effective time period for controlling climate within the enclosure. Once the reaction goes to completion or reaches a point where recharging is desirable, the thermochemical reaction can be reversed by adding heat back to the products of the exothermic reaction. In one aspect, the products of the thermochemical reaction can be heated to about 80 to about 250 degrees Celsius for a period of about 60 to about 80 minutes to reverse the thermochemical reaction, thus allowing multiple iterations of the disclosed method of controlling climate within an enclosure.
Thermal flows can be directed from the reversible thermochemical reaction in a variety of ways. Heat generated from the exothermic reaction can be collected via a heat transfer fluid and the heated heat transfer fluid can be used to condition air to provide a heating effect within the enclosure. The heating effect provided via the heat transfer fluid can be achieved by convection or by forced air. Similarly, thermal flows from the endothermic reaction can also be directed using a heat transfer fluid. Heat can be transferred from the heat transfer fluid to drive the endothermic reaction and the cooled heat transfer fluid can be used to cool conditioned air and provide a cooling effect in the enclosure. Similarly, the cooling effect provided via the heat transfer fluid can be achieved by convection or by forced air.
A single heating bed including a compacted metal chloride salt (MgCl2) was connected to a single cooling bed including ammonia via a connecting conduit. A flow control mechanism was included along the connecting conduit to control the fluid flow of the ammonia between the cooling bed and the heating bed. This particular thermal battery had an energy capacity of 70 Wh/170 Wh for cooling and heating, respectively. This disparate ratio is due to the evaporation enthalpy of ammonia (23.53 kJ/mol-NH3) being smaller than that of ammonia adsorption on MgCl2, forming MgCl2(NH3)6 (55.7 kJ/mol-NH3).
The battery was prepared by allowing the MgCl2 to fully react with ammonia to obtain ammonia salt powder MgCl2(NH3)6. The ammonia salt powder was then mixed with 20 wt % of expandable graphite and pressed into dense discs. The discs were loaded into a finned stainless steel tube. This stainless steel tube was connected to another finned stainless steel tube via a connecting conduit fitted with a flow control valve. The valve was opened and the system was recharged by heating the heating bed to between 200 and 250° C. for less than 80 minutes to release the ammonia from the heating bed and drive it to the cooling bed to condense. The valve was then closed to store the battery for testing.
The data collected and illustrated in
It is also noted that when air was blown across both the heating and cooling beds, the discharging process was much faster and could be completed in only 15 minutes. Under these circumstances a thermal battery system with an energy capacity of 2.5 kWh/6 kWh can provide a cooling and heating power of 10 kWh/24 kWh, respectively.
The importance of low porosity levels in the compacted metal salt pellets or discs is illustrated by
One example system can have the parameters outlined in Table 2 below. Specifically, the example system can include a heating bed packed at a 95% packing density with compacted MgCl2(NH3)6 pellets, each pellet having a density of 1.25 kg/L, and the total combined pellet mass being about 25.6 g. The thermal battery can be charged using a resistance heating wire to dissociate the ammonia from the metal salt and drive it toward the cooling bed. Upon charging the thermal battery, about 6.6 kg of ammonia can be transferred to the cooling bed, leaving about 19.0 kg of metal salt in the heating bed. The total heating bed volume in this system can be about 16 L with a metal salt volume of about 15.2 L. The total volume of the system can be about 27 L. Such a system can provide at least about 2.5 kWh of cooling energy and 2.5 kWh heating energy.
This thermal battery can be compared to alternative thermal batteries prepared with other compacted metal salts, as outlined in Table 3 below.
As can be seen from Table 3, there are a variety of compacted metal salts that can be used to prepare a suitable heating bed. However, it is noted that the examples listed in Table 3 are non-limiting examples and that there are other compacted metal salts that can also be used, as discussed previously.
The foregoing detailed description describes the invention with reference to specific exemplary embodiments. However, it will be appreciated that various modifications and changes can be made without departing from the scope of the present invention as set forth in the appended claims. The detailed description and accompanying drawings are to be regarded as merely illustrative, rather than as restrictive, and all such modifications or changes, if any, are intended to fall within the scope of the present invention as described and set forth herein.
This application is related to U.S. Provisional Application No. 62/066,753, filed Oct. 21, 2014, and U.S. Provisional Application No. 62/119,595, filed Feb. 23, 2015, which are each incorporated herein by reference.
This invention was made with government support under Grant No. DE-AR0000173 awarded by U.S. Department of Energy. The government has certain rights in the invention.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US15/56733 | 10/21/2015 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62066753 | Oct 2014 | US | |
| 62119595 | Feb 2015 | US |
