Overheat controlled thermal storage

Abstract

The invention relates to overheat controlled thermal storage. A vapor compression system includes a compressor, a condenser, an expansion device, and an evaporator fluidly connected to form a closed fluid circuit having a working fluid circulating therethrough. The thermal storage device includes a storage material, and the thermal storage device is thermally coupled to the closed fluid circuit downstream of the expansion device with respect to the flow of the working fluid. The vapor compression system is controllable such that the heat storage device is operable to both store and release heat when the working fluid circulates through the closed fluid circuit in a given direction.

Description

Technical Field

[0001] Exemplary embodiments of this disclosure relate to the field of condensers, and more particularly, to a vapor compression system having various means for removing heat from a refrigerant therein. Background Technology

[0002] Conventional vapor compression systems have condensers sized based on the maximum load at the highest ambient temperature. However, maximum load and maximum ambient temperature do not always exist. Sizing the heat exchanger system for the maximum heat load under continuous operating cycles with the maximum expected ambient air conditions results in oversized, overweight, and overpowered condensing units for those parts of the operating cycle that are not approaching the system's limits. Furthermore, because electricity costs increase during peak periods, such as when ambient temperatures are highest, it is desirable to shift the vapor compression cycle's operational dependence on electricity to off-peak times, such as during the early morning, midday, and evening hours. Summary of the Invention

[0003] According to an embodiment, a vapor compression system includes a compressor, a condenser, an expander, and an evaporator, which are fluidly connected to form a closed fluid loop having a working fluid circulating through it. A heat storage device includes a storage material, and the flow of the heat storage device relative to the working fluid is thermally coupled to the closed fluid loop downstream of the expander. The vapor compression system is controllable such that the heat storage device can be operated to both store and release heat when the working fluid circulates through the closed fluid loop in a given direction.

[0004] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the vapor compression system includes a counterflow valve that allows the working fluid to move through a closed fluid loop in a first direction associated with a cooling mode and in a second direction opposite to a heating mode.

[0005] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the heat storage device may be operated to both store and release heat when the vapor compression system is in cooling mode.

[0006] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the controller is operatively coupled to the compressor and the expander, and the controller is operable to control the overheating of the working fluid at the compressor inlet.

[0007] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the controller may be operable to adjust the position of the expander to control the overheating of the working fluid at the compressor inlet.

[0008] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the storage material is a phase change material.

[0009] According to an embodiment, a vapor compression system includes a compressor, a condenser, an expander, and an evaporator, which are fluidly connected to form a closed fluid loop having a working fluid circulating through it. A heat storage device includes a storage material, and the flow of the heat storage device relative to the working fluid is thermally coupled to the closed fluid loop downstream of the compressor and upstream of the expander. The vapor compression system is controllable such that the heat storage device can be operated to both store and release heat when the working fluid circulates through the closed fluid loop in a given direction.

[0010] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the vapor compression system includes a counterflow valve that allows the working fluid to move through a closed fluid loop in a first direction associated with a cooling mode and in a second direction opposite to a heating mode.

[0011] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the heat storage device may be operated to both store and release heat when the vapor compression system is in cooling mode.

[0012] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the controller is operatively coupled to the compressor and the expander, and the controller is operable to control the overheating of the working fluid at the compressor inlet.

[0013] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the controller may be operable to adjust the position of the expander to control the overheating of the working fluid at the compressor inlet.

[0014] According to an embodiment, a method of operating a vapor compression system includes: circulating a working fluid through a closed fluid loop, the closed fluid loop including a compressor, a condenser, an expander, and an evaporator; and releasing energy from a heat storage device thermally coupled to the closed fluid loop by controlling the superheating of the working fluid at the compressor.

[0015] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, controlling the overheating of the working fluid includes controlling the position of the expansion device.

[0016] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, discharging the thermal storage device further includes reducing the overheating of the working fluid.

[0017] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the overheating of the working fluid is reduced by increasing the flow of the working fluid at the expansion device.

[0018] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the thermal storage device thermally coupled to a closed fluid loop is energized by controlling the overheating of the working fluid at the compressor.

[0019] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the working fluid circulates in the same direction through a closed fluid loop during both charging and discharging of the thermal storage device.

[0020] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, energizing the thermal storage device includes transferring thermal energy from the working fluid to the storage material of the thermal storage device.

[0021] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, energizing the thermal storage device includes reducing the overheating of the working fluid.

[0022] In addition to one or more of the features described above, or as an alternative to any of the foregoing embodiments, the overheating of the working fluid is reduced by adjusting the position of the expansion device to reduce the flow of the working fluid at the expansion device. Attached Figure Description

[0023] The following description should not be considered as limiting in any way. Referring to the accompanying drawings, similar elements are similarly numbered: Figure 1 This is a schematic diagram of a vapor compression system in cooling mode according to an embodiment; Figure 2 According to another embodiment in heating mode Figure 1 A schematic diagram of a vapor compression system; Figure 3This is a schematic diagram of another vapor compression system in cooling mode according to another embodiment; and Figure 4 This is a schematic diagram of another vapor compression system in cooling mode according to another embodiment. Detailed Implementation

[0024] A detailed description of one or more embodiments of the disclosed apparatus and methods is presented herein by way of illustration rather than limitation, with reference to the accompanying drawings.

[0025] Now for reference Figure 1 An example of a vapor compression system 20 with a closed fluid loop is provided, in which a working fluid R (such as, for example, a refrigerant) circulates. As shown, the vapor compression system 20 includes one or more compressors 22, a first heat exchanger 24, an expansion device 26, and a second heat exchanger 28. In operation, the compressor 22 receives working fluid vapor from the second heat exchanger 28 and compresses it to a high temperature and high pressure. The relatively hot working fluid vapor R is then conveyed to the first heat exchanger 24, where the working fluid vapor R is cooled and condensed to a liquid state via a heat exchange relationship with a cooling medium C1 (such as, for example, air or water). Therefore, the first heat exchanger 24 is a heat exhaust heat exchanger or a condenser.

[0026] Cooled liquid working fluid R flows from the first heat exchanger 24 to an expansion device 26 (such as, for example, an expansion valve), where the working fluid R is expanded to a lower pressure, at which the temperature decreases, and the working fluid R may exist in a two-phase liquid / vapor state. The working fluid R is then supplied from the expansion device 26 to a second heat exchanger 28. Because heat is transferred from the secondary medium C2 (such as, for example, air) to the refrigerant R within the second heat exchanger 28, causing any refrigerant R in the liquid phase to vaporize, the second heat exchanger 28 functions as an endothermic heat exchanger or evaporator. The low-pressure vapor working fluid R returns from the second heat exchanger 28 to the compressor 22, making the cycle repeatable. In an embodiment, as shown, the system 20 may additionally include an accumulator or separator 32 positioned directly upstream of the inlet of the compressor 22. In such an embodiment, any liquid working fluid may be collected within the separator 32, such that only the vaporized working fluid R is supplied to the compressor 22.

[0027] In one embodiment, the vapor compression system 20 may be a heat pump. In such an embodiment, the vapor compression system 20 includes a backflow valve 30 operable to control the direction of flow of the working fluid R within the system 20. For example, when the backflow valve 30 is in a first position, as... Figure 1As shown, the vapor compression system 20 can be considered to be in "cooling" mode, and the working fluid R can flow in the manner described above. When the backflow valve 30 is in the second position, as... Figure 2 As shown, the vapor compression system 20 can be considered to be in a "heating" mode. In the heating mode, the working fluid R can flow in the reverse direction, such as from the compressor 22 to the second heat exchanger 28, to the expander 26, and to the first heat exchanger 24, before returning to the compressor 22 to repeat the cycle. Although only a single expander 26 is illustrated and described herein, it should be understood that embodiments in which the vapor compression system 20 includes both a first and a second expander are also within the scope of this disclosure. In such embodiments, the first expander may be associated with a cooling mode and the flow of the working fluid in a first direction, and the second expander may be associated with operation in a heating mode and the flow of the working fluid in a second direction.

[0028] In each of the illustrated non-limiting embodiments, the vapor compression system 20 is thermally coupled to a heat storage device 40 containing stored material. In another illustrated non-limiting embodiment, the vapor compression system 20 is indirectly thermally coupled to the heat storage device 40 via a heat exchanger 42. The heat storage device 40 and the heat exchanger 42 are fluidly coupled to form a closed loop through which a heat transfer fluid circulates. The closed loop may include a pump 44 operable to drive the movement of the heat transfer fluid between the heat exchanger 42 and the heat storage device 40. When the vapor compression is indirectly thermally coupled to the heat storage device 40, the refrigerant R of the vapor compression system 20 is arranged to have a heat transfer relationship with the heat transfer fluid at the heat exchanger 42. However, in other embodiments, the working fluid R may be directly thermally coupled to the heat storage device 40. For example, all or at least a portion of the working fluid R within the vapor compression system 20 may be configured to flow through one or more channels formed in the heat storage device 40.

[0029] The thermal storage device 40 may be filled with a phase change material P, which is capable of transitioning between a first phase and a second phase. The phase change material P may be capable of transitioning between a solid and a liquid state. In embodiments, the phase change material P is a low-temperature melting material, such as having a transition temperature between solid and liquid of less than about 11°C. For example, the phase change material P may be a low-temperature melting inorganic hydrate, which transitions between a solution of the hydrate in a liquid at a high temperature and a crystalline hydrate in a liquid at a low temperature. However, other suitable phase change materials P (such as, for example, organic paraffins, organic esters (e.g., dimethyl adipate), or ice) are also within the scope of this disclosure.

[0030] The heat storage device 40 can be used to remove heat from or release heat into the working fluid R within the vapor compression system 20. In an embodiment, the same flow of the working fluid R can be used to both charge (provide heat energy to the heat storage device 40) and release (remove heat energy from the heat storage device 40). This charging and releasing can be performed by controlling the superheating of the working fluid R before it enters the compressor 22. In the illustrated non-limiting embodiment, the location for controlling the superheating of the working fluid R is arranged directly upstream of the compressor 22 and is indicated by the numeral 60. In this embodiment, the compressor 22 is a variable-speed compressor.

[0031] exist Figure 1 In the illustrated non-limiting embodiment, the thermal interface or connection between the vapor compression system 20 and the heat storage device 40 is located between the expansion device 26 and the second heat exchanger 28 relative to the flow of the working fluid R. Figure 2 In a non-limiting embodiment, the thermal coupling between the closed fluid loop of the working fluid R and the heat storage device 40 is located upstream of the expansion device 26 and downstream of a corresponding heat exchanger that can operate as a condenser. In embodiments that include a first expansion device and a second expansion device, the heat storage device 40 may be thermally coupled to the closed fluid loop at a location between the first expansion device and the second expansion device.

[0032] However, embodiments in which the heat storage device 40 is arranged at another location surrounding the vapor compression system 20 are also envisioned herein. For example, in Figure 3 In a non-limiting embodiment of the vapor compression system 20 illustrated, in cooling mode, the thermal interface or connection between the vapor compression system 20 and the heat storage device 40 is located between the outlet of the compressor 22 and upstream of a corresponding heat exchanger that can operate as a condenser, relative to the flow direction of the working fluid R. Figure 4 In another embodiment illustrated herein, in cooling mode, the heat storage device is thermally coupled to the vapor compression system 20 at a location between the first heat exchanger 24 and the expansion device 26 relative to the direction of flow of the working fluid R.

[0033] Such as about Figure 1 and Figure 2As described in the illustrated embodiment, the heat storage device 40 can be directly thermally coupled to the vapor compression system 20, or alternatively, indirectly thermally coupled to the vapor compression system 20. As shown, the heat storage device 40 is fluidly connected to the heat exchanger 42 and the pump 44, and the flow of the working fluid R is configured to pass through the heat exchanger 42. The heat storage device 40 may be filled with a phase change material P, which can transform between a first phase and a second phase (such as between a solid and a liquid). In the embodiment where, in cooling mode, the flow of the heat storage device 40 relative to the working fluid R is downstream of the compressor 22 and upstream of the expansion device 26 (…),… Figure 3 and Figure 4 In this context, the phase change material P is a high-temperature molten material, such as when the heat storage device 40 is upstream of the condenser 24, the phase change material P has a transition temperature between solid and liquid between about 75°C and 100°C, or when the heat storage device 40 is downstream of the condenser 24, the phase change material P has a transition temperature between solid and liquid between about 30°C and 50°C.

[0034] The superheat of the working fluid R of the vapor compression system 20, identified by the numeral 60 in the figure, can be controlled to selectively store heat (i.e., charge) or discharge heat (i.e., release) from the heat storage device 40. The expansion device 26 of the vapor compression system 20 can be adjusted as needed (e.g., via controller 50) to achieve the desired superheat of the working fluid R at the compressor 22. For example, the expansion device 26 can be adjusted to reduce the flow of the working fluid R through it, thereby increasing the superheat. Increasing the superheat temperature of the working fluid R at position 60 lowers the temperature of the working fluid R directly downstream of the expansion device 26. Alternatively or additionally, the expansion device 26 can be adjusted to increase the flow of the working fluid R through it, thereby reducing the superheat within the system 20. As a result, the temperature of the working fluid R directly downstream of the expansion device 26, directly upstream of the expansion device 26, or directly upstream of the first heat exchanger 24 can be controlled based on the desired superheat of the vapor compression system 20. Lowering the superheat temperature of the working fluid R increases the temperature of the working fluid R directly downstream of the expansion device 26.

[0035] Continue to refer to Figure 1 and Figure 2To "charge" the thermal storage device 40, the vapor compression system 20 can operate with a relatively low first superheat. This first superheat can be selected such that the temperature of the working fluid R, directly downstream of the expansion device 26 configured to expand the working fluid R, exceeds the temperature of the stored material. In embodiments where the stored material is a phase change material, the temperature of the working fluid R exceeds the phase change temperature of the phase change material during the energization (melting) of the thermal storage device 40. The vapor compression system 20 can maintain operating parameters such that some or all of the phase change material within the thermal storage device 40 has transitioned from a first state to a second state in response to absorbing heat energy from the working fluid R. The controller 50 may include or be operatively coupled to a sensor operable to detect when the phase change material has reached its maximum thermal storage capacity. In other embodiments, the controller 50 may simply maintain operating conditions for a fixed period of time associated with energizing the thermal storage device 40.

[0036] To discharge heat from the heat storage device 40, the vapor compression system 20 can operate with a relatively increased second superheat. As previously mentioned, this increased superheat can be achieved by reducing the flow of the working fluid R at the corresponding expansion device 26. The second superheat temperature is higher than the first superheat temperature. This second superheat temperature can be selected such that the temperature of the working fluid R directly downstream of the expansion device 26 is lower than the phase change temperature of the phase change material during the energy release of the heat storage device 40. Therefore, when the working fluid R output from the expansion device 26 is arranged in thermal communication with the phase change material, heat is transferred from the phase change material to the working fluid R.

[0037] The vapor compression system 20 can maintain operating parameters until some or all of the phase change material within the heat storage device 40 has transitioned from the second state to the first state in response to the release of heat energy to the working fluid R. As previously mentioned, the controller 50 can sense when the phase change material has reached its minimum heat storage capacity and can adjust the operation of the vapor compression system in response to such determination. Alternatively, the controller 50 can maintain operating conditions for a fixed period of time associated with the complete release of heat energy from the heat storage device 40.

[0038] Similarly, refer to Figure 4The operation of the vapor compression system 20 with a relatively low first superheat causes the temperature upstream of the expansion device 26 to exceed the temperature of the stored material. Therefore, when operating with the first superheat, the heat storage device 40 located between the first heat exchanger 24 and the expansion device 26 can be energized. As the superheat of the vapor compression system increases, the temperature of the working fluid R downstream of the first heat exchanger 24 will decrease, for example, to a temperature lower than the phase change temperature of the phase change material in the heat storage device 40. Therefore, when the working fluid R output from the first heat exchanger 24 is arranged in thermal communication with the phase change material, heat is transferred from the phase change material to the working fluid R.

[0039] refer to Figure 3 When operating in cooling mode, the vapor compression system 20 operates with a relatively low first superheat, resulting in temperatures downstream of compressor 22 and upstream of the first heat exchanger 24 that are lower than the phase change temperature of the phase change material in the heat storage device 40. Therefore, when the working fluid R output from compressor 22 is arranged in thermal communication with the phase change material, heat is transferred from the phase change material to the working fluid R. As the superheat of the vapor compression system increases, the temperature of the working fluid R downstream of the first heat exchanger 24 will increase, for example, to a temperature greater than the phase change temperature of the phase change material in the heat storage device 40. Therefore, in embodiments where the heat storage device 40 is thermally coupled to the vapor compression circuit at a location between compressor 22 and the first heat exchanger 24 in cooling mode, increased superheat can be used to energize the heat storage device 40.

[0040] In one embodiment, the controller 50 can control the overheating of the vapor compression system 20 to reduce the energy required by the compressor 22. Specifically, the controller 50 can control the energy release of the heat storage device 40 to reduce the energy required by the compressor 22.

[0041] The vapor compression system 20 described herein incorporates a heat storage device in a simplified manner. Unlike existing systems that rely on complex valve and piping arrangements to guide the evaporation of refrigerant to solidify the phase change material and the condensation of refrigerant to melt the phase change material, the same flow of refrigerant can be operated to melt and solidify both the phase change material without complex piping and valves.

[0042] The term “about” is intended to include the degree of error associated with measurements based on a specific quantity of equipment available at the time of filing this application.

[0043] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that, when used in this specification, the terms “comprising” and / or “including” specify the presence of the stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof.

[0044] While this disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may replace its elements without departing from the scope of this disclosure. Furthermore, many modifications may be made to adapt particular situations or materials to the teachings of this disclosure without departing from the essential scope of this disclosure. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed as the best mode contemplated for carrying out this disclosure, but that this disclosure will include all embodiments falling within the scope of the claims.

Claims

1. A vapor compression system, comprising: A compressor, a condenser, an expander, and an evaporator are fluidly connected to form a closed fluid loop, the closed fluid loop having a working fluid circulating through the closed fluid loop; A thermal storage device comprising a storage material, wherein the flow of the thermal storage device relative to the working fluid is thermally coupled to the closed fluid loop downstream of the expansion device; and The vapor compression system is controllable such that the heat storage device is operable to both store and release heat when the working fluid circulates through the closed fluid loop in a given direction.

2. The vapor compression system of claim 1, further comprising a counterflow valve, such that the working fluid can move through the closed fluid loop in a first direction associated with a cooling mode and in a second direction opposite to a heating mode.

3. The vapor compression system according to claim 2, wherein, When the vapor compression system is in the cooling mode, the heat storage device is operable to both store and release heat.

4. The vapor compression system according to any one of the preceding claims, further comprising a controller operatively coupled to the compressor and the expander, wherein, The controller is operable to control the overheating of the working fluid at the inlet of the compressor.

5. The vapor compression system according to claim 4, wherein, The controller is operable to adjust the position of the expansion device to control the superheating of the working fluid at the inlet of the compressor.

6. The vapor compression system according to any one of the preceding claims, wherein, The storage material is a phase change material.

7. A vapor compression system, comprising: A compressor, a condenser, an expander, and an evaporator are fluidly connected to form a closed fluid loop, the closed fluid loop having a working fluid circulating through the closed fluid loop; A thermal storage device comprising a storage material, wherein the thermal storage device is thermally coupled to the closed fluid loop downstream of the compressor and upstream of the expansion device relative to the flow of the working fluid; and The vapor compression system is controllable such that the heat storage device is operable to both store and release heat when the working fluid circulates through the closed fluid loop in a given direction.

8. The vapor compression system of claim 7, further comprising a counterflow valve, such that the working fluid can move through the closed fluid loop in a first direction associated with a cooling mode and in a second direction opposite to a heating mode.

9. The vapor compression system according to claim 8, wherein, When the vapor compression system is in the cooling mode, the heat storage device is operable to both store and release heat.

10. The vapor compression system according to any one of the preceding claims, further comprising a controller operatively coupled to the compressor and the expander, wherein, The controller is operable to control the overheating of the working fluid at the inlet of the compressor.

11. The vapor compression system according to claim 10, wherein, The controller is operable to adjust the position of the expansion device to control the superheating of the working fluid at the inlet of the compressor.

12. A method of operating a vapor compression system, comprising: The working fluid is circulated through a closed fluid loop, which includes a compressor, a condenser, an expander, and an evaporator; as well as The heat storage device, which is thermally coupled to the closed fluid circuit, is released by controlling the overheating of the working fluid at the compressor.

13. The method according to claim 12, wherein, Controlling the overheating of the working fluid includes controlling the position of the expansion device.

14. The method according to any one of claims 12-13, wherein, Discharging the heat storage device further includes reducing the overheating of the working fluid.

15. The method according to claim 14, wherein, The overheating of the working fluid is reduced by increasing the flow of the working fluid at the expansion device.

16. The method according to any one of claims 12-15, further comprising energizing the thermal storage device thermally coupled to the closed fluid circuit by controlling the overheating of the working fluid at the compressor.

17. The method according to claim 16, wherein, During both charging and discharging of the thermal storage device, the working fluid circulates through the closed fluid loop in the same direction.

18. The method according to claim 16 or claim 17, wherein, Charging the thermal storage device includes transferring thermal energy from the working fluid to the storage material of the thermal storage device.

19. The method according to any one of claims 16-18, wherein, Charging the thermal storage device further includes reducing the overheating of the working fluid.

20. The method according to claim 19, wherein, The overheating of the working fluid is reduced by adjusting the position of the expansion device to reduce the flow of the working fluid at the expansion device.

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