Swimming Pool or Spa Heat Pump With Refrigerant Charge Compensator and Method of Operating Same

Abstract

A swimming pool or spa heat pump operable in cooling and heating modes, along with a method of operating same is disclosed. The heat pump includes a compressor, first and second heat exchangers, refrigerant charge compensator, and at least one means for lowering the pressure of refrigerant provided to the first and second heat exchangers. The first heat exchanger is configured to transfer thermal energy to and/or extract thermal energy from a first fluid, and the second heat exchanger is configured to transfer thermal energy to and/or extract thermal energy from pool or spa water. The refrigerant charge compensator is configured to reduce an amount of active refrigerant charge in circulation in the heat pump when the heat pump is operated in the cooling mode and increase the amount of active refrigerant charge in circulation when the heat pump is operated in the heating mode.

Claims

1. A swimming pool or spa heat pump capable of operating in a cooling mode of operation and a heating mode of operation, comprising: a compressor; a first heat exchanger configured to transfer thermal energy to and/or extract thermal energy from a first fluid; a second heat exchanger configured to transfer thermal energy to and/or extract thermal energy from a second fluid, the second fluid being pool or spa water; at least one means for lowering the pressure of refrigerant being provided to the first heat exchanger when the heat pump is operated in the heating mode of operation and lowering the pressure of refrigerant being provided to the second heat exchanger when the heat pump is operated in the cooling mode of operation; and a refrigerant charge compensator configured to reduce an amount of active refrigerant charge in circulation in the heat pump when the heat pump is operated in the cooling mode of operation and increase the amount of active refrigerant charge in circulation in the heat pump when the heat pump is operated in the heating mode of operation.

2. The swimming pool or spa heat pump of claim 1, comprising: a reversing valve fluidly coupled with the compressor, the first heat exchanger, and the second heat exchanger, the reversing valve configured to receive pressurized refrigerant from the compressor, direct the pressurized refrigerant to the first heat exchanger when the heat pump is in the cooling mode of operation, and direct the pressurized refrigerant to the second heat exchanger when the heat pump is in the heating mode of operation, wherein the refrigerant charge compensator is positioned between the second heat exchanger and the reversing valve.

3. The swimming pool or spa heat pump of claim 1, wherein the refrigerant charge compensator is configured to (1) cause refrigerant to be removed from circulation when the heat pump is operated in the cooling mode of operation and store the removed refrigerant, and (2) cause refrigerant stored by the refrigerant charge compensator to reenter circulation when the heat pump is operated in the heating mode of operation.

4. The swimming pool or spa heat pump of claim 1, wherein the first heat exchanger is a microchannel coil heat exchanger.

5. The swimming pool or spa heat pump of claim 1, wherein said at least one means includes an expansion valve assembly.

6. The swimming pool or spa heat pump of claim 1, wherein the first heat exchanger has a lower heat transfer flux than the second heat exchanger.

7. The swimming pool or spa heat pump of claim 1, wherein the refrigerant charge compensator is configured to (1) cause refrigerant to be removed from circulation when low-temperature refrigerant flows through the refrigerant charge compensator, and (2) cause refrigerant to renter circulation when high-temperature refrigerant flows through the refrigerant charge compensator.

8. The swimming pool or spa heat pump of claim 1, wherein the refrigerant charge compensator includes a chamber in fluidic communication with a liquid refrigerant line of the heat pump.

9. The swimming pool or spa heat pump of claim 8, wherein the liquid refrigerant line extends between the first heat exchanger and the at least one means for lowering the pressure of refrigerant.

10. The swimming pool or spa heat pump of claim 1, comprising an accumulator configured to receive low-pressure, low-temperature refrigerant.

11. A method of operating a heat pump capable of operating in a cooling mode of operation and a heating mode of operation, comprising: increasing the pressure of refrigerant with a compressor to generate high-pressure, high-temperature refrigerant; causing the high-pressure, high-temperature refrigerant to flow through a first heat exchanger and transfer thermal energy to a first fluid; reducing the pressure and the temperature of the high-pressure, high-temperature refrigerant to generate low-pressure, low-temperature refrigerant; causing the low-pressure, low-temperature refrigerant to flow through a second heat exchanger and extract thermal energy from a second fluid, the second fluid being pool or spa water; causing the low-pressure, low-temperature refrigerant to flow through a refrigerant charge compensator after flowing through the second heat exchanger, the refrigerant charge compensator positioned between the second heat exchanger and a reversing valve; reducing an amount of active refrigerant charge in circulation in the heat pump with the refrigerant charge compensator; and returning the low-pressure, low-temperature refrigerant to the compressor.

12. The method of claim 11, comprising the steps of: increasing the pressure of the low-pressure, low-temperature refrigerant returned to the compressor to generate high-pressure, high-temperature refrigerant; causing the high-pressure, high-temperature refrigerant to flow through the refrigerant charge compensator; increasing the amount of active refrigerant charge in circulation in the heat pump with the refrigerant charge compensator; causing the high-pressure, high-temperature refrigerant to flow through the second heat exchanger and transfer thermal energy to the second fluid; reducing the pressure and the temperature of the high-temperature refrigerant to generate low-pressure, low-temperature refrigerant; causing the low-pressure, low-temperature refrigerant to flow through the first heat exchanger; and returning the low-pressure, low-temperature refrigerant to the compressor.

13. The method of claim 12, comprising: causing, with the refrigerant charge compensator, refrigerant to be removed from circulation when the heat pump is operated in a cooling mode of operation and storing the removed refrigerant; and causing refrigerant stored by the refrigerant charge compensator to reenter circulation when the heat pump is operated in a heating mode of operation.

14. The method of claim 11, wherein the first heat exchanger is a microchannel coil heat exchanger.

15. The method of claim 11, wherein the refrigerant charge compensator includes a chamber in fluidic communication with a liquid refrigerant line of the heat pump.

16. The method of claim 15, wherein the liquid refrigerant line extends between the first heat exchanger and at least one means for lowering the pressure of refrigerant.

17. The method of claim 11, wherein the first heat exchanger has a lower heat transfer flux than the second heat exchanger.

18. The method of claim 11, comprising: causing refrigerant to be removed from circulation when low-temperature refrigerant flows through the refrigerant charge compensator; and causing refrigerant to reenter circulation when the high-temperature refrigerant flows through the refrigerant charge compensator.

19. A swimming pool or spa heat pump capable of operating in a cooling mode of operation and a heating mode of operation, comprising: a housing; a compressor; a first heat exchanger configured to transfer thermal energy to and extract thermal energy from ambient air, the first heat exchanger being a microchannel heat exchanger; a fan configured to blow ambient air across the first heat exchanger; a second heat exchanger configured to transfer thermal energy to and extract thermal energy from pool or spa water; a reversing valve fluidly coupled with the compressor, the first heat exchanger, and the second heat exchanger, the reversing valve being configured to receive pressurized refrigerant from the compressor, direct the pressurized refrigerant to the first heat exchanger when the heat pump is in the cooling mode of operation, and direct the pressurized refrigerant to the second heat exchanger when the heat pump is in the heating mode of operation; at least one means for lowering the pressure of refrigerant being provided to the first heat exchanger when the heat pump is operated in the heating mode of operation and lowering the pressure of refrigerant being provided to the second heat exchanger when the heat pump is operated in the cooling mode of operation; and a refrigerant charge compensator having a chamber in fluidic communication with a refrigerant line at a position between the first heat exchanger and the second heat exchanger, the refrigerant charge compensator being configured to (1) cause refrigerant to be removed from circulation and stored in the chamber to reduce an amount of active refrigerant charge in circulation in the heat pump when the heat pump is operated in the cooling mode of operation and (2) cause refrigerant stored in the chamber to reenter circulation to increase the amount of active refrigerant charge in circulation in the heat pump when the heat pump is operated in the heating mode of operation, wherein the first heat exchanger has a lower heat transfer flux than the second heat exchanger.

20. The swimming pool or spa heat pump of claim 19 in combination with a swimming pool filtration pump for circulating the pool or spa water through the second heat exchanger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing features of the invention will be apparent from the following Detailed Description, taken in connection with the accompanying drawings, in which:

[0014] FIG. 1 is a schematic diagram of an HVAC or refrigeration heat pump system of the prior art in a heating mode of operation;

[0015] FIG. 2 is a schematic diagram of the HVAC or refrigeration heat pump system of FIG. 1 in a cooling mode of operation;

[0016] FIG. 3 is a schematic diagram of a swimming pool or spa heat pump system of the prior art in a heating mode of operation;

[0017] FIG. 4 is a schematic diagram of the swimming pool or spa heat pump system of FIG. 3 in a cooling mode of operation;

[0018] FIG. 5 is a schematic diagram of a swimming pool or spa heat pump system of the present invention in a cooling mode of operation;

[0019] FIG. 6 is a schematic diagram of the swimming pool or spa heat pump system of the present invention in a heating mode of operation;

[0020] FIG. 7 is a schematic diagram of another swimming pool or spa heat pump system of the present invention in a cooling mode of operation; and

[0021] FIG. 8 is a schematic diagram of the swimming pool or spa heat pump system of FIG. 7 in a heating mode of operation.

DETAILED DESCRIPTION

[0022] The present disclosure relates to swimming pool or spa heat pump systems that implement a refrigerant charge compensator to account for refrigerant charge imbalances between heating and cooling modes of operation, as discussed in detail below in connection with FIGS. 1-8.

[0023] FIG. 1 is a schematic diagram of an HVAC or refrigeration heat pump system 100 of the prior art in a heating mode of operation. The heat pump system 100 includes a compressor 102, an accumulator, 104, a reversing valve 106, a first refrigerant-to-air heat exchanger 108, a first expansion valve assembly 110, a filter/drier 112, a second expansion valve assembly 114, a second refrigerant-to-air heat exchanger 116, and a refrigerant charge compensator 118. During the heating mode of operation, the compressor 102 compresses the refrigerant into a high-pressure and high-temperature state, and causes the pressurized refrigerant to flow from an outlet 120 thereof to the reversing valve 106 by way of tubing. The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the reversing valve 106 and to the first refrigerant-to-air heat exchanger 108.

[0024] The first heat exchanger 108 can be a tube-and-fin heat exchanger that is utilized to provide conditioned air to a user's environment, e.g., a room. For example, the first heat exchanger 108 can be an indoor coil having a fan associated therewith that blows air across the heat exchanger 108 and to a desired room such that the heat generated by the heat exchanger 108 is transferred to the air, e.g., the first heat exchanger 108 can be a refrigerant-to-air heat exchanger for heating air to be provided to a room. The refrigerant then exits the first heat exchanger 108 and flows through the first expansion valve assembly 110 (which is not operational to cause fluid expansion in the heating mode of operation), through the filter/drier 112, and through the second expansion valve assembly 114. The second expansion valve assembly 114 controls the amount of refrigerant released to the second refrigerant-to-air heat exchanger 116 and causes the temperature of the refrigerant to lower. Additional thermal energy is removed from the refrigerant as it passes through the second heat exchanger 116, which can be a tube-and-fin heat exchanger that is utilized to extract additional energy from the refrigerant. The second heat exchanger 116 can be an outdoor coil having a fan associated therewith that blows air across the heat exchanger 116 and to the ambient air. Cooled refrigerant then exits the second heat exchanger 116 and flows through the refrigerant charge compensator 118, which is installed in the vapor line between the second heat exchanger 116 and the reversing valve 106.

[0025] During the heating mode of operation shown in FIG. 1, the low temperature of the vapor refrigerant flowing through the refrigerant charge compensator 118 causes refrigerant to be pulled from the refrigerant liquid line, e.g., at a point between the first and second expansion valve assemblies 110, 114, and into a tank or chamber of the refrigerant charge compensator 118. Thus, a portion of the refrigerant is pulled out of circulation and rendered inactive, as the heat pump system 100 generally requires less active refrigerant in the heating mode of operation compared to the cooling mode of operation. In particular, the refrigerant stored in the refrigerant charge compensator 118 is generally excess refrigerant that would otherwise be backed up in the first heat exchanger 108 causing an increase in discharge pressure and reducing the heat output from the first heat exchanger 108. By storing the excess refrigerant in the refrigerant charge compensator 118, and rendering it inactive in the refrigeration circuit, the system 100 can better control distribution of the refrigerant therein and pressure within the system 100, which results in an increase in system efficiency. Accordingly, the refrigerant charge compensator 118 is used to account for the different amount of refrigerant charge that is optimum for each mode of operation, e.g., heating mode versus cooling mode.

[0026] The refrigerant flowing through the refrigerant charge compensator 118 continues through the reversing valve 106 and to the accumulator 104, which is installed in the suction line between the reversing valve 106 and the compressor 102. The refrigerant then exits the accumulator 104 and enters the compressor 102 where it restarts the refrigeration cycle.

[0027] FIG. 2 is a schematic diagram of the HVAC or refrigeration heat pump system 100 of FIG. 1 in a cooling mode of operation. During the cooling mode of operation, the compressor 100 compresses the refrigerant into a high-pressure and high-temperature state, and causes the pressurized refrigerant to flow from an outlet 120 thereof to the reversing valve 106 by way of tubing. The reversing valve 106, now in the cooling mode of operation position, directs the pressurized refrigerant toward the refrigerant charge compensator 118 and the second refrigerant-to-air heat exchanger 116, instead of toward the first refrigerant-to-air heat exchanger 108, as it did when it was in the heating mode of operation position. That is, the reversing valve 106 controls in which direction the high-pressure, high-temperature refrigerant flows based on the mode of operation.

[0028] The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the refrigerant charge compensator 118. During the cooling mode of operation shown in FIG. 2, the high temperature of the liquid refrigerant flowing through the refrigerant charge compensator 118 causes refrigerant stored in the refrigerant charge compensator 118 to increase in temperature and be forced back into the liquid line of the heat pump system, e.g., at a point between the first and second expansion valve assemblies 110, 114, where it is reintroduced into circulation, e.g., it is rendered active again. This results in an increase in efficiency of the heat pump system 100 since it is able to use the entire refrigerant charge when operated in the cooling mode of operation.

[0029] The refrigerant flowing through the refrigerant charge compensator 118 continues to, and flows through, the second heat exchanger 116. The refrigerant can increase in temperature as it flows through the second heat exchanger 116, e.g., by absorbing heat from the ambient air. The high-pressure, high-temperature liquid refrigerant then exits the second heat exchanger 116 and flows through the second expansion valve assembly 114 (which is not operational to cause fluid expansion in the cooling mode of operation), through the filter/drier 112, and through the first expansion valve assembly 110. The first expansion valve assembly 110 controls the amount of refrigerant released to the first refrigerant-to-air heat exchanger 108 and causes the temperature of the refrigerant to lower. The fan associated with the first refrigerant-to-air heat exchanger 108 can blow air across the first heat exchanger 108 and to a desired room such that the cool refrigerant flowing through the first heat exchanger 108 extracts thermal energy from the air, thus cooling the air that is blowing across the first heat exchanger 108 and to the room. The refrigerant then exits the first heat exchanger 108, passes through the reversing valve 106, and continues to the accumulator 104. The refrigerant then exits the accumulator 104 and enters the compressor 102 where it restarts the refrigeration cycle.

[0030] Accordingly, when in the heating mode of operation, the heat pump system 100 uses less refrigerant charge, the magnitude of which is dependent upon the tank size of the refrigerant charge compensator 118, in comparison to the cooling mode of operation during which the heat pump system 100 uses the entire refrigerant charge.

[0031] Swimming pool or spa heat pump heaters are similar to those used in HVAC and refrigeration systems, such as the HVAC or refrigeration heat pump system 100 shown and described in connection with FIGS. 1 and 2, but instead of using a refrigerant-to-air heat exchanger for the first heat exchanger 108, e.g., the heat exchanger that is used to provide conditioned (cooled/heated) fluid, swimming pool or spa heat pump heaters use a refrigerant-to-water heat exchanger to heat or cool the pool or spa water. FIG. 3 is a schematic diagram of a swimming pool or spa heat pump system 200 of the prior art in a heating mode of operation. The heat pump system 200 includes a compressor 202, an accumulator 204, a reversing valve 206, a first refrigerant-to-water heat exchanger 208, a first expansion valve assembly 210, a filter/drier 212, a second expansion valve assembly 214, a second refrigerant-to-air heat exchanger 216, and a refrigerant charge compensator 218. During the heating mode of operation, the compressor 202 compresses the refrigerant into a high-pressure and high-temperature state, and causes the pressurized refrigerant to flow from an outlet 220 thereof to the reversing valve 206 by way of tubing. The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the reversing valve 206 and to the first refrigerant-to-air heat exchanger 108.

[0032] The first heat exchanger 208 can be a tube-and-fin heat exchanger that is utilized to provide temperature conditioned water to a pool or spa. For example, the first heat exchanger 208 can have a swimming pool filtration pump associated therewith that pumps pool/spa water through the heat exchanger 208 and to the pool/spa such that the heat generated by the heat exchanger 208 is transferred to the pool/spa water, e.g., the first heat exchanger 208 can be a refrigerant-to-water heat exchanger for heating pool/spa water. The refrigerant then exits the first heat exchanger 208 and flows through the first expansion valve assembly 210 (which is not operational to cause fluid expansion in the heating mode of operation), through the filter/drier 212, and through the second expansion valve assembly 214. The second expansion valve assembly 214 controls the amount of refrigerant released to the second refrigerant-to-air heat exchanger 216 and causes the temperature of the refrigerant to lower. Additional thermal energy is removed from the refrigerant as it passes through the second heat exchanger 216, which can be a tube-and-fin heat exchanger that is utilized to extract additional energy from the refrigerant. The second heat exchanger 216 can be an outdoor coil having a fan associated therewith that blows air across the heat exchanger 216 and to the ambient air. Cooled refrigerant then exits the second heat exchanger 216 and flows through the refrigerant charge compensator 218, which is installed in the vapor line between the second heat exchanger 216 and the reversing valve 206.

[0033] During the heating mode of operation shown in FIG. 3, the low temperature of the vapor refrigerant flowing through the refrigerant charge compensator 218 causes refrigerant to be pulled from the refrigerant liquid line, e.g., at a point between the first and second expansion valve assemblies 210, 214, and into a tank or chamber of the refrigerant charge compensator 218. Thus, a portion of the refrigerant is pulled out of circulation and rendered inactive, as the heat pump system 200 generally requires less active refrigerant in the heating mode of operation compared to the cooling mode of operation. In this regard, the refrigerant stored in the refrigerant charge compensator 218 is generally excess refrigerant that would otherwise be backed up in the first heat exchanger 208 causing an increase in discharge pressure and reducing the heat output from the first heat exchanger 208. By storing the excess refrigerant in the refrigerant charge compensator 218, and rendering it inactive in the refrigeration circuit, the system 200 can better control distribution of the refrigerant therein and pressure within the system 200, which results in an increase in system efficiency. Accordingly, the refrigerant charge compensator 218 is used to account for the different amount of refrigerant charge that is optimum for each mode of operation, e.g., heating mode versus cooling mode.

[0034] The refrigerant flowing through the refrigerant charge compensator 218 continues through the reversing valve 206 and to the accumulator 204, which is installed in the suction line between the reversing valve 206 and the compressor 102. The refrigerant then exits the accumulator 204 and enters the compressor 102 where it restarts the refrigeration cycle.

[0035] FIG. 4 is a schematic diagram of the swimming pool or spa heat pump system 200 of FIG. 3 in a cooling mode of operation. During the cooling mode of operation, the compressor 202 compresses the refrigerant into a high-pressure and high-temperature state, and causes the pressurized refrigerant to flow from an outlet 220 thereof to the reversing valve 206 by way of tubing. The reversing valve 206, now in the cooling mode of operation position, directs the pressurized refrigerant toward the refrigerant charge compensator 218 and the second refrigerant-to-air heat exchanger 216, instead of toward the first refrigerant-to-water heat exchanger 208, as it did when it was in the heating mode of operation position. That is, the reversing valve 206 controls in which direction the high-pressure, high-temperature refrigerant flows based on the mode of operation.

[0036] The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the refrigerant charge compensator 218. During the cooling mode of operation shown in FIG. 4, the high temperature of the liquid refrigerant flowing through the refrigerant charge compensator 218 causes refrigerant stored in the refrigerant charge compensator 218 to increase in temperature and be forced back into the liquid line of the heat pump system, e.g., at a point between the first and second expansion valve assemblies 210, 214, where it is reintroduced into circulation, e.g., it is rendered active again. This results in an increase in efficiency of the heat pump system 200 since it is able to use the entire refrigerant charge when operated in the cooling mode of operation.

[0037] The refrigerant flowing through the refrigerant charge compensator 218 continues to, and flows through, the second heat exchanger 216. The refrigerant can increase in temperature as it flows through the second heat exchanger 216, e.g., by absorbing heat from the ambient air. The high-pressure, high-temperature liquid refrigerant then exits the second heat exchanger 216 and flows through the second expansion valve assembly 214 (which is not operational to cause fluid expansion in the cooling mode of operation), through the filter/drier 212, and through the first expansion valve assembly 210. The first expansion valve assembly 210 controls the amount of refrigerant released to the first refrigerant-to-water heat exchanger 208 and causes the temperature of the refrigerant to lower. The swimming pool filtration pump associated with the first refrigerant-to-water heat exchanger 208 can pump pool/spa water through the first heat exchanger 208 and to the pool/spa such that the cool refrigerant flowing through the first heat exchanger 208 extracts thermal energy from the water, thus cooling the water that is being pumped across the first heat exchanger 208 and to the pool/spa. The refrigerant then exits the first heat exchanger 208, passes through the reversing valve 206, and continues to the accumulator 204. The refrigerant then exits the accumulator 204 and enters the compressor 202 where it restarts the refrigeration cycle.

[0038] Accordingly, when in the heating mode of operation, the heat pump system 200 uses less refrigerant charge, the magnitude of which is dependent upon the tank size of the refrigerant charge compensator 218, in comparison to the cooling mode of operation during which the heat pump system 200 uses the entire refrigerant charge.

[0039] However, pool/spa heat pump systems that utilize microchannel coil heat exchangers, e.g., for the refrigerant-to-air heat exchanger and/or refrigerant-to-water heat exchanger of the heat pump system, have different refrigerant requirements in the heating and cooling modes of operation compared to prior art heat pump systems that utilize, for example, tube-and-fin heat exchangers for the refrigerant-to-air heat exchanger and/or refrigerant-to-water heat exchanger. In particular, application of microchannel coil heat exchangers, e.g., for the refrigerant-to-air heat exchanger, causes the refrigerant charge imbalance for the heat pump system to shift such that the heat pump requires more active refrigerant charge in the heating mode of operation than in the cooling mode of operation, which is opposite to conventional pool or spa heat pumps. This imbalance is due, at least in part, to the increased efficiency and heat transfer capabilities of microchannel coil heat exchangers. Microchannel coil heat exchangers include multiple layers of stacked thin plates or fins that create a series of small channels, which results in a high ratio of surface area to volume and additional surface area for contact with a working fluid (e.g., air or pool/spa water) that facilitates the transfer of heat and increases heat transfer efficiency. The aforementioned imbalance shift is addressed in the present disclosure by positioning a refrigerant charge compensator in the system at a location such that excess refrigerant is pulled into the refrigerant charge compensator, e.g., made inactive, during the cooling mode of operation and pushed back into refrigerant cycle, e.g., made active, during the heating mode of operation.

[0040] FIG. 5 is a schematic diagram of a swimming pool or spa heat pump system 300 of the present invention in a cooling mode of operation, and FIG. 6 is a schematic diagram of the swimming pool or spa heat pump system 300 of the present invention in a heating mode of operation.

[0041] The heat pump system 300 includes a compressor 302, an optional accumulator 304, a reversing valve 306, a first refrigerant-to-air heat exchanger 308 (e.g., heating mode evaporator, which can be a microchannel heat exchanger), a first expansion valve assembly 310, a filter/drier 312, a second expansion valve assembly 314, a second refrigerant-to-water heat exchanger 316 (e.g., cooling mode evaporator, which can be a shell-and-tube heat exchanger or a microchannel heat exchanger), and a refrigerant charge compensator 318 positioned between the reversing valve 306 and the refrigerant-to-water heat exchanger 316. The components of the pool or spa heat pump system 300 are configured to cycle refrigerant there through in order to perform the desired heating or cooling function. It should be understood that the first and second expansion valve assemblies 310, 314 can be provided as a single unit. It should also be understood that one or more of the aforementioned components of the heat pump system 300 can be provided in a housing.

[0042] The compressor 302 is configured to increase the pressure and temperature of the system's refrigerant, and provide the high-pressure, high-temperature liquid refrigerant to the reversing valve 306 through tubing. The reversing valve 306 is configured to receive the high-pressure, high-temperature refrigerant from the compressor 302 and selectively direct the refrigerant to either the first refrigerant-to-air heat exchanger 308 or the second refrigerant-to-water heat exchanger 316 depending on the mode of operation. The first refrigerant-to-air heat exchanger 308 and/or the second refrigerant-to-water heat exchanger 316 can be a microchannel heat exchanger.

[0043] As shown in FIG. 5, when the heat pump system 300 is in a cooling mode of operation, the reversing valve 306 is configured to receive the high-pressure, high-temperature refrigerant from the compressor 302 and direct the high-pressure, high-temperature refrigerant to the first refrigerant-to-air heat exchanger 308. Additionally, when in the cooling mode of operation, the reversing valve 306 is configured to receive low-pressure, low-temperature refrigerant from the second refrigerant-to-water heat exchanger 316 and direct the low-pressure, low-temperature refrigerant therefrom to the optional accumulator 304 and the suction side of the compressor 302.

[0044] As shown in FIG. 6, when the heat pump system 300 is in a heating mode of operation, the reversing valve 306 is configured to receive the high-pressure, high-temperature refrigerant from the compressor 302 and direct the high-pressure, high-temperature refrigerant to the second refrigerant-to-water heat exchanger 316. Additionally, when in the heating mode of operation, the reversing valve 306 is configured to receive low-pressure, low-temperature refrigerant from the first refrigerant-to-air heat exchanger 308 and direct the low-pressure, low-temperature refrigerant therefrom to the optional accumulator 304 and the suction side of the compressor 302.

[0045] The first refrigerant-to-air heat exchanger 308 can be a microchannel heat exchanger, a tube-and-fin heat exchanger, a channel fin heat exchanger, etc., that is configured to receive high-pressure, high-temperature refrigerant from the reversing valve 306 when the system 300 is in the cooling mode of operation. The first refrigerant-to-air heat exchanger 308 can have a fan associated therewith that blows air across the heat exchanger 308. Alternatively, when the system 300 is in the heating mode of operation (see FIG. 6), the first refrigerant-to-air heat exchanger 308 is configured to receive low-pressure, low-temperature refrigerant from the first expansion valve assembly 310, and assists the first expansion valve assembly 310 with converting the refrigerant from liquid into gas.

[0046] The first expansion valve assembly 310, e.g., thermal expansion valve, is configured to permit high-pressure, high-temperature refrigerant to flow there through and to the filter/drier 312 during the cooling mode of operation. However, when the system 300 is in the heating mode of operation (see FIG. 6), the first expansion valve assembly 310 receives high-pressure, high-temperature liquid refrigerant from the filter/drier 312 and is configured to control the flow of refrigerant into the first refrigerant-to-air heat exchanger 308 in order cause the refrigerant to go from a high-pressure, high-temperature liquid state to a low-pressure, low-temperature gaseous state.

[0047] When the system 300 is in the cooling mode of operation, the filter/drier 312 receives refrigerant from the first expansion valve assembly 310, whereas when the system 300 is in the heating mode of operation, the filter/drier 312 receives refrigerant from the second expansion valve assembly 314. The filter/drier 312 removes debris, particular matter, and moisture from the refrigerant.

[0048] The second expansion valve assembly 314, e.g., thermal expansion valve, is configured to receive high-pressure, high-temperature refrigerant from the filter/drier 312 when the system 300 is operated in the cooling mode of operation. The second expansion valve assembly 314 receives the high-pressure, high-temperature liquid refrigerant from the filter/drier 312 and is configured to control the flow of refrigerant into the second refrigerant-to-water heat exchanger 316 in order cause the refrigerant to go from a high-pressure, high-temperature liquid state to a low-pressure, low-temperature gaseous state. Alternatively, when the system 300 is operated in the heating mode of operation (see FIG. 6), the second expansion valve assembly 314 is configured to permit high-pressure, high-temperature refrigerant to flow there through and to the filter/drier 312.

[0049] When the system 300 is in the cooling mode of operation, the second refrigerant-to-water heat exchanger 316 receives the low-pressure, low-temperature gaseous refrigerant from the second expansion valve assembly 314, which flows there through. The refrigerant-to-water heat exchanger 316 can be a microchannel coil heat exchanger, a shell-and-tube heat exchanger, or other heat exchanger that is utilized to provide temperature conditioned water to the pool or spa. For example, the second refrigerant-to-water heat exchanger 316 can have a swimming pool filtration pump associated therewith that pumps pool/spa water through the second heat exchanger 316 and to the pool/spa such that the cool refrigerant flowing through the second heat exchanger 316 during the cooling mode of operation extracts thermal energy from the water, thus cooling the water that is being pumped across the second heat exchanger 316 and to the pool/spa. Alternatively, when the system 300 is operated in the heating mode of operation (see FIG. 6), the second refrigerant-to-water heat exchanger 316 receives high-pressure, high-temperature refrigerant that has passed through the refrigerant charge compensator 318 that is positioned between the reversing valve 306 and the second heat exchanger 316. Pool/spa water is pumped through the second refrigerant-to-water heat exchanger 316, e.g., by the associated swimming pool filtration pump, and to the pool/spa such that heat generated by the second heat exchanger 316 due to the high-pressure, high-temperature refrigerant flowing there through is transferred to the pool/spa water. This results in the heating of the pool/spa water, which is circulated back to the pool/spa.

[0050] During the cooling mode of operation, the cooled gascous refrigerant exits the second heat exchanger 316 and passes through the refrigerant charge compensator 318, which is installed in the vapor line between the second heat exchanger 316 and the reversing valve 306. The refrigerant charge compensator 318 is configured to draw a portion of the refrigerant out of circulation during the cooling mode of operation, and store the drawn out refrigerant until the system 300 is switched to the heating mode of operation, which is described in greater detail below in connection with FIG. 5 and the description of the cooling mode of operation. For example, the refrigerant charge compensator 318 can include tubing that connects a tank or chamber thereof with the refrigerant line connecting the filter/drier 312 and the second expansion valve assembly 314. However, during the heating mode of operation (see FIG. 6), high-pressure, high-temperature liquid refrigerant flows from the reversing valve 306, through the refrigerant charge compensator 318, and to the second refrigerant-to-water heat exchanger 316. The high-temperature liquid refrigerant flowing through the refrigerant charge compensator 318 heats the cool refrigerant stored in the refrigerant charge compensator 318 causing the refrigerant to migrate back into circulation, as shown and described in greater detail below in connection with FIG. 6 and the description of the heating mode of operation.

[0051] The reversing valve 306 receives low-pressure, low-temperature gaseous refrigerant from the refrigerant charge compensator 318 when the system 300 is operated in the cooling mode of operation (see FIG. 5) or from the first refrigerant-to-air heat exchanger 308 when the system 300 is operated in the heating mode of operation (see FIG. 6). The reversing valve 306 directs the gaseous refrigerant toward the accumulator 304, which can store excess liquid refrigerant until it is required by the system 300. The refrigerant passes through the accumulator 304 and enters a suction side inlet or port of the compressor 302.

The Cooling Mode of Operation

[0052] During the cooling mode of operation, the compressor 300 compresses the refrigerant into a high-pressure and high-temperature state, and causes the pressurized refrigerant to flow from an outlet 320 thereof to the reversing valve 306 by way of tubing. The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the reversing valve 306 and to the first refrigerant-to-air heat exchanger 308.

[0053] As previously noted, the first refrigerant-to-air heat exchanger 308 can be a microchannel heat exchanger or a tube-and-fin heat exchanger that can have a fan associated therewith that blows air across the heat exchanger 308. The refrigerant then exits the first heat exchanger 308 and flows through the first expansion valve assembly 310 (which is not operational to cause fluid expansion in the heating mode of operation), through the filter/drier 312, and through the second expansion valve assembly 314. The second expansion valve assembly 314 controls the amount of refrigerant released to the second refrigerant-to-water heat exchanger 316, and causes the pressure and temperature of the refrigerant to lower. The refrigerant-to-water heat exchanger 316 can be a tube-and-fin heat exchanger, a shell-and-tube heat exchanger, or a microchannel coil heat exchanger that is utilized to provide temperature conditioned water to the pool or spa. For example, the refrigerant-to-water heat exchanger 316 can have a swimming pool filtration pump associated therewith that pumps pool/spa water through the heat exchanger 316 and to the pool/spa such that the cool refrigerant flowing through the second heat exchanger 316 extracts thermal energy from the water, thus cooling the water that is being pumped across the second heat exchanger 316 and to the pool/spa.

[0054] The cooled refrigerant then exits the second heat exchanger 316 and flows through the refrigerant charge compensator 318, which is installed in the vapor line between the second heat exchanger 316 and the reversing valve 306. During the cooling mode of operation shown in FIG. 5, the gaseous refrigerant passing through the second heat exchanger 316 is the lowest temperature gas in the system. Accordingly, the low-temperature vapor refrigerant flowing through the refrigerant charge compensator 318, e.g., through a center tube thereof, lowers the temperature of the refrigerant reservoir of the refrigerant charge compensator 318, which in turn causes refrigerant to be pulled from the refrigerant liquid line, e.g., at a point between the first and second expansion valve assemblies 310, 314, and into a tank or chamber of the refrigerant charge compensator 318 because liquid refrigerant will migrate to the lowest temperature point in the refrigerant path, e.g., the tank or chamber of the refrigerant charge compensator 318.

[0055] Thus, a portion of the refrigerant is pulled out of circulation and rendered inactive, as the heat pump system 300 generally requires less active refrigerant in the cooling mode of operation compared to the heating mode of operation due, at least in part, to the difference in internal volume and heat transfer flux distribution of the heat exchangers 308, 316, e.g., the microchannel coil heat exchanger used for the refrigerant-to-air heat exchanger 308 compared to the heat exchanger used for the refrigerant-to-water heat exchanger 316. The refrigerant stored in the refrigerant charge compensator 318 is generally excess refrigerant that would otherwise be backed up in the second refrigerant-to-water heat exchanger 316 causing an increase in discharge pressure and reducing the output from the second heat exchanger 316. By storing the excess refrigerant in the refrigerant charge compensator 318, and rendering it inactive in the refrigeration circuit, the system 300 can better control distribution of the refrigerant therein and pressure within the system 300, which results in an increase in system efficiency. When the refrigerant charge compensator 318 is sized for the amount of refrigerant charge imbalance in the system 300, the charge compensator 318 will fill with enough refrigerant to balance the system 300 and lower the pressure that would otherwise occur due to extra refrigerant charge. Accordingly, the refrigerant charge compensator 318 is used to account for the different amount of refrigerant charge that is optimum for each mode of operation, e.g., heating mode versus cooling mode.

[0056] The refrigerant flowing through the refrigerant charge compensator 318 continues through the reversing valve 306 and to the accumulator 304, which is installed in the suction line between the reversing valve 306 and the compressor 302. The refrigerant then exits the accumulator 304 and enters the compressor 302 where it restarts the refrigeration cycle.

The Heating Mode of Operation

[0057] FIG. 6 is a schematic diagram of the swimming pool or spa heat pump system 300 of FIG. 5 in a heating mode of operation. During the heating mode of operation, the compressor 302 compresses the refrigerant into a high-pressure, high-temperature state, and causes the pressurized refrigerant to flow from the outlet 320 thereof to the reversing valve 306 by way of tubing. The reversing valve 306, now in the heating mode of operation position, directs the pressurized refrigerant toward the refrigerant charge compensator 318 and the second refrigerant-to-water heat exchanger 316, instead of toward the first refrigerant-to-air heat exchanger 308, as it did when it was in the cooling mode of operation position.

[0058] The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the refrigerant charge compensator 318. During the heating mode of operation shown in FIG. 6, the high-temperature of the liquid refrigerant flowing through the refrigerant charge compensator 318, e.g., through a center tube thereof, causes refrigerant stored therein to increase in temperature and be forced back into the liquid line of the heat pump system 300, e.g., at a point between the first and second expansion valve assemblies 310, 314, where it reenters or is reintroduced into circulation, e.g., it is made active again. This results in an increase in efficiency of the heat pump system 300 since it is able to use the entire refrigerant charge when operated in the heating mode of operation.

[0059] The high-temperature refrigerant flowing through the refrigerant charge compensator 318 continues to, and flows through, the second refrigerant-to-water heat exchanger 316. As previously described, pool/spa water is pumped through the second refrigerant-to-water heat exchanger 316, e.g., by an associated swimming pool filtration pump, and to the pool/spa such that heat generated by the heat exchanger 316 due to the high temperature refrigerant flowing there through is transferred to the pool/spa water. This results in the heating of the pool/spa water, which is circulated back to the pool/spa. The high-pressure, high-temperature refrigerant then exits the second heat exchanger 316 and flows through the second expansion valve assembly 314 (which is not operational to cause fluid expansion in the heating mode of operation), through the filter/drier 312, and through the first expansion valve assembly 310. The first expansion valve assembly 310 controls the amount of refrigerant released to the first refrigerant-to-air heat exchanger 308, and causes the pressure and temperature of the refrigerant to lower. This results in the refrigerant changing from liquid phase to gaseous phase. Additional thermal energy is removed from the refrigerant as it passes through the first heat exchanger 308, which can be an outdoor coil having a fan associated therewith that blows air across the first heat exchanger 308 and to the ambient air. Cooled gaseous refrigerant then exits the first heat exchanger 308, flows through the reversing valve 306, and continues to the optional accumulator 304. The refrigerant then exits the accumulator 304 and enters the compressor 302 where it restarts the refrigeration cycle.

[0060] FIG. 7 is a schematic diagram of another swimming pool or spa heat pump system 400 of the present invention in a cooling mode of operation. FIG. 8 is a schematic diagram of the swimming pool or spa heat pump system 400 of FIG. 7 in a heating mode of operation. The heat pump system 400 of FIGS. 7 and 8 is substantially similar in construction and operation to the heat pump system 300 shown and described in connection with FIGS. 5 and 6. Accordingly, like elements are labelled with like reference numerals, but increased by one-hundred.

[0061] The heat pump system 400 includes a compressor 402, a reversing valve 406, a refrigerant-to-air heat exchanger 408 (e.g., air coil, heating mode evaporator), which can be a microchannel heat exchanger, an expansion valve assembly 410 (e.g., thermal expansion valve), a filter/drier 412, a refrigerant-to-water heat exchanger 416 (e.g., water coil, cooling mode evaporator), and a refrigerant charge compensator 418 positioned between the reversing valve 406 and the refrigerant-to-water heat exchanger 416. The components of the pool or spa heat pump system 400 are configured to cycle refrigerant there through in order to perform the desired heating or cooling function. It should also be understood that one or more of the aforementioned components of the heat pump system 300 can be provided in a housing.

[0062] The compressor 402 is configured to increase the pressure and temperature of the system's refrigerant, and provide compressed vapor refrigerant to the reversing valve 406 through tubing. The reversing valve 406 is configured to receive the compressed vapor refrigerant from the compressor 402 and selectively direct the refrigerant to either the refrigerant-to-air heat exchanger 408 or the refrigerant-to-water heat exchanger 416 depending on the mode of operation. The refrigerant-to-air heat exchanger 408 can be a microchannel heat exchanger.

[0063] As shown in FIG. 7, when the heat pump system 400 is in a cooling mode of operation, the reversing valve 406 is configured to receive the compressed vapor refrigerant from the compressor 402 and direct the compressed vapor refrigerant to the refrigerant-to-air heat exchanger 408. Additionally, when in the cooling mode of operation, the reversing valve 406 is configured to receive superheated vapor refrigerant from the refrigerant-to-water heat exchanger 416 and direct the superheated vapor refrigerant to the suction side of the compressor 402.

[0064] As shown in FIG. 8, when the heat pump system 400 is in a heating mode of operation, the reversing valve 406 is configured to receive the compressed vapor refrigerant from the compressor 402 and direct the compressed vapor refrigerant to the refrigerant-to-water heat exchanger 416. Additionally, when in the heating mode of operation, the reversing valve 406 is configured to receive superheated vapor refrigerant from the refrigerant-to-air heat exchanger 408 and direct the superheated vapor refrigerant to the suction side of the compressor 402.

[0065] The refrigerant-to-air heat exchanger 408 can be a microchannel heat exchanger, a tube-and-fin heat exchanger, a channel fin heat exchanger, etc., that is configured to receive compressed vapor refrigerant from the reversing valve 406 when the system 400 is in the cooling mode of operation. The refrigerant-to-air heat exchanger 408 can have a fan associated therewith that blows air across the heat exchanger 408. Alternatively, when the system 400 is in the heating mode of operation (see FIG. 8), the refrigerant-to-air heat exchanger 408 is configured to receive two-phase refrigerant from the expansion valve assembly 410, and assists the expansion valve assembly 410 with converting the refrigerant into superheated vapor.

[0066] When the system 400 is in the cooling mode of operation, the expansion valve assembly 410 receives sub-cooled liquid from the refrigerant-to-air heat exchanger 408 and is configured to control the flow of refrigerant to the refrigerant-to-water heat exchanger 416 in order to cause the refrigerant to change from sub-cooled liquid to two-phase, e.g., to change from a high-pressure, high-temperature liquid state to a low-pressure, low-temperature gaseous state. The refrigerant is then provided to the filter/drier 412. However, when the system 400 is in the heating mode of operation (see FIG. 8), the expansion valve assembly 410 receives sub-cooled liquid refrigerant from the filter/drier 412, by way of the refrigerant-to-water heat exchanger 416, and is configured to control the flow of refrigerant into the refrigerant-to-air heat exchanger 408 in order cause the refrigerant to change from sub-cooled liquid to two-phase, e.g., to change from a high-pressure, high temperature liquid state to a low-pressure, low-temperature gaseous state. The filter/drier 312 removes debris, particular matter, and moisture from the refrigerant as it passes therethrough.

[0067] When the system 400 is in the cooling mode of operation, the refrigerant-to-water heat exchanger 416 receives the low-pressure, low-temperature gaseous (two-phase) refrigerant from the expansion valve assembly 410. The refrigerant-to-water heat exchanger 416 is utilized to provide temperature conditioned water to the pool or spa. For example, the refrigerant-to-water heat exchanger 416 can have a swimming pool filtration pump associated therewith that pumps pool/spa water through the refrigerant-to-water heat exchanger 416 and to the pool/spa such that the cool refrigerant flowing through the refrigerant-to-water heat exchanger 416 during the cooling mode of operation extracts thermal energy from the water, thus cooling the water that is being pumped across the refrigerant-to-water heat exchanger 416 and to the pool/spa. Alternatively, when the system 400 is operated in the heating mode of operation (see FIG. 8), the refrigerant-to-water heat exchanger 416 receives high-pressure, high-temperature (compressed vapor) refrigerant that has passed through the refrigerant charge compensator 418 that is positioned between the reversing valve 406 and the refrigerant-to-water heat exchanger 416. Pool/spa water is pumped through the refrigerant-to-water heat exchanger 416, e.g., by the associated swimming pool filtration pump, and to the pool/spa such that heat generated by the refrigerant-to-water heat exchanger 416 due to the high-pressure, high-temperature refrigerant flowing there through is transferred to the pool/spa water. This results in the heating of the pool/spa water, which is circulated back to the pool/spa.

[0068] During the cooling mode of operation, the cooled gaseous (superheated vapor) refrigerant exits the refrigerant-to-water heat exchanger 416 and passes through the refrigerant charge compensator 418, which is installed in the vapor line between the refrigerant-to-water heat exchanger 416 and the reversing valve 406. The refrigerant charge compensator 418 is configured to draw a portion of the refrigerant out of circulation during the cooling mode of operation, and store the drawn out refrigerant until the system 400 is switched to the heating mode of operation, which is described in greater detail below in connection with FIG. 7 and the description of the cooling mode of operation. For example, the refrigerant charge compensator 418 can include tubing that connects a tank or chamber thereof with the refrigerant line extending between the expansion valve 410 and the refrigerant-to-air heat exchanger 408. However, during the heating mode of operation (see FIG. 8), high-pressure, high-temperature (compressed vapor) liquid refrigerant flows from the reversing valve 406, through the refrigerant charge compensator 418, and to the refrigerant-to-water heat exchanger 416. The high-temperature liquid refrigerant flowing through the refrigerant charge compensator 418 heats the cool refrigerant stored in the refrigerant charge compensator 418 causing the refrigerant to migrate back into circulation, as shown and described in greater detail below in connection with FIG. 8 and the description of the heating mode of operation.

[0069] The reversing valve 406 receives low-pressure, low-temperature gaseous (superheated vapor) refrigerant from the refrigerant charge compensator 418 when the system 400 is operated in the cooling mode of operation (see FIG. 7) or from the refrigerant-to-air heat exchanger 408 when the system 400 is operated in the heating mode of operation (see FIG. 8). The reversing valve 406 directs the gaseous refrigerant to a suction side inlet or port 422 of the compressor 302.

The Cooling Mode of Operation

[0070] FIG. 7 is a schematic diagram of the swimming pool or spa heat pump system 400 in a cooling mode of operation. During the cooling mode of operation, the compressor 400 compresses the refrigerant into a high-pressure and high-temperature state (e.g., compressed vapor), and causes the pressurized refrigerant to flow from an outlet 420 thereof to the reversing valve 406 by way of tubing. The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the reversing valve 406 and to the refrigerant-to-air heat exchanger 408.

[0071] As previously noted, the refrigerant-to-air heat exchanger 408 can be a microchannel heat exchanger or a tube-and-fin heat exchanger, which can have a fan associated therewith that blows air across the heat exchanger 408. The refrigerant flowing through the refrigerant-to-air heat exchanger 408 changes state as it flows therethrough, e.g., from compressed vapor, to saturated vapor, and then to sub-cooled liquid as it exits the heat exchanger 408. The refrigerant then exits the heat exchanger 408 and flows through the expansion valve assembly 410, which controls the amount of refrigerant released, and causes the pressure and temperature of the refrigerant to lower such that the refrigerant changes phase again, e.g., into two-phase refrigerant. The refrigerant then flows through the filter/drier 412 and to the refrigerant-to-water heat exchanger 416, which is utilized to provide temperature conditioned water to the pool or spa. For example, the refrigerant-to-water heat exchanger 416 can have a swimming pool filtration pump associated therewith that pumps pool/spa water through the heat exchanger 416 and to the pool/spa such that the cool refrigerant flowing through the heat exchanger 416 extracts thermal energy from the water, thus cooling the water that is being pumped across the heat exchanger 416 and to the pool/spa.

[0072] The cooled (superheated vapor) refrigerant then exits the refrigerant-to-water heat exchanger 416 and flows through the refrigerant charge compensator 418, which is installed in the vapor line between the refrigerant-to-water heat exchanger 416 and the reversing valve 406. During the cooling mode of operation shown in FIG. 7, the superheated vapor refrigerant passing through and exiting the refrigerant-to-water heat exchanger 416 is the lowest temperature gas in the system. Accordingly, the low-temperature vapor (e.g., superheated vapor) refrigerant flowing through the refrigerant charge compensator 418, e.g., through a center tube thereof, lowers the temperature of the refrigerant reservoir of the refrigerant charge compensator 418, which in turn causes refrigerant to be pulled from the refrigerant liquid line, e.g., at a point between the expansion valve assembly 410 and the refrigerant-to-air heat exchanger 408, and into a tank or chamber of the refrigerant charge compensator 418 because liquid refrigerant will migrate to the lowest temperature point in the refrigerant path, e.g., the tank or chamber of the refrigerant charge compensator 418.

[0073] Thus, a portion of the refrigerant is pulled out of circulation and rendered inactive, as the heat pump system 400 generally requires less active refrigerant in the cooling mode of operation compared to the heating mode of operation due, at least in part, to the difference in internal volume and heat transfer flux distribution of the microchannel coil heat exchanger being used. The refrigerant stored in the refrigerant charge compensator 418 is generally excess refrigerant that would otherwise be backed up in the refrigerant-to-water heat exchanger 416 causing an increase in discharge pressure and reducing the output from the second heat exchanger 416. By storing the excess refrigerant in the refrigerant charge compensator 418, and rendering it inactive in the refrigeration circuit, the system 400 can better control distribution of the refrigerant therein and pressure within the system 400, which results in an increase in system efficiency. When the refrigerant charge compensator 418 is sized for the amount of refrigerant charge imbalance in the system 400, the charge compensator 418 will fill with enough refrigerant to balance the system 400 and lower the pressure that would otherwise occur due to extra refrigerant charge. Accordingly, the refrigerant charge compensator 418 is used to account for the different amount of refrigerant charge that is optimum for each mode of operation, e.g., heating mode versus cooling mode.

[0074] The refrigerant flowing through the refrigerant charge compensator 418 continues through the reversing valve 406 and to a suction side inlet or port 422 of the compressor 302, where it enters the compressor 302 and restarts the refrigeration cycle.

The Heating Mode of Operation

[0075] FIG. 8 is a schematic diagram of the swimming pool or spa heat pump system 400 of FIG. 7 in a heating mode of operation. During the heating mode of operation, the compressor 402 compresses the refrigerant into a high-pressure, high-temperature state (e.g., compressed vapor), and causes the pressurized refrigerant to flow from the outlet 420 thereof to the reversing valve 406 by way of tubing. The reversing valve 406, now in the heating mode of operation position, directs the pressurized refrigerant toward the refrigerant charge compensator 418 and the refrigerant-to-water heat exchanger 416, instead of toward the refrigerant-to-air heat exchanger 408 as it did when it was in the cooling mode of operation position.

[0076] The pressurized refrigerant, which has increased in temperature due to the increase in pressure, flows through the refrigerant charge compensator 418. During the heating mode of operation shown in FIG. 8, the high-temperature of the liquid refrigerant flowing through the refrigerant charge compensator 418, e.g., through a center tube thereof, causes refrigerant stored therein to increase in temperature and be forced back into the liquid line of the heat pump system 400, e.g., at a point between the expansion valve assembly 410 and the refrigerant-to-air heat exchanger 408, where it reenters or is reintroduced into circulation, e.g., it is made active again. This results in an increase in efficiency of the heat pump system 400 since it is able to use the entire refrigerant charge when operated in the heating mode of operation.

[0077] The high-temperature refrigerant flowing through the refrigerant charge compensator 418 continues to, and flows through, the refrigerant-to-water heat exchanger 416. As previously described, pool/spa water is pumped through the refrigerant-to-water heat exchanger 416, e.g., by an associated swimming pool filtration pump, and to the pool/spa such that heat generated by the heat exchanger 416 due to the high temperature refrigerant flowing there through is transferred to the pool/spa water. This results in heating of the pool/spa water, which is circulated back to the pool/spa. The refrigerant changes phase, e.g., from a compressed vapor to a saturated vapor and then to a sub-cooled liquid, as the pool/spa water extracts thermal energy therefrom. The high-pressure, high-temperature (sub-cooled) refrigerant then exits the refrigerant-to-water heat exchanger 416 and flows through the filter/drier 412 to the expansion valve assembly 410. The expansion valve assembly 410 controls the amount of refrigerant released to the refrigerant-to-air heat exchanger 408, e.g., microchannel heat exchanger, and causes the pressure and temperature of the refrigerant to lower. This results in the refrigerant changing from liquid phase to gaseous phase, e.g., from sub-cooled liquid to two-phase refrigerant. Additional thermal energy is removed from the refrigerant as it passes through the refrigerant-to-air heat exchanger 408, which can be an outdoor coil having a fan associated therewith that blows air across the heat exchanger 408 and to the ambient air. Cooled gaseous (e.g., superheated vapor) refrigerant then exits the heat exchanger 408, flows through the reversing valve 406, and continues to the suction side inlet or port 422 of the compressor 302 where it restarts the refrigeration cycle.

[0078] Accordingly, when in the cooling mode of operation, the heat pump systems 300, 400 use less refrigerant charge, the magnitude of which is dependent upon the tank size of the refrigerant charge compensator 318, 418, in comparison to the heating mode of operation during which the heat pump systems 300, 400 use the entire refrigerant charge. Thus, the refrigerant charge compensator 318, 418 provides an active method to lower the high-pressure encountered in the cooling mode of operation to enable better cooling performance without sacrificing heating performance.

[0079] Thus, the heat pump systems 300, 400 of FIGS. 5-8 route high-temperature, high-pressure refrigerant through the refrigerant charge compensator 318, 418 when operated in heating mode compared to prior art heat pumps systems, such as the heat pump systems 100, 200 shown and described in connection with FIGS. 1-4, which route high-temperature, high-pressure refrigerant through the refrigerant charge compensator 118, 218 when operated in cooling mode.

[0080] Additional and/or alternative modifications to the systems 300, 400 can be implemented to assist with addressing the charge imbalance in heating and cooling modes of operation. For example, the volume of airflow through the first refrigerant-to-air heat exchanger 308, 408 could be increased in order to lower the pressure of the system 300, 400 in the cooling mode of operation. This could be achieved by, for example, using a larger fan/motor assembly or using additional fan/motor assemblies. The surface area of the first refrigerant-to-air heat exchanger 308, 408 and/or the amount of energy used to move air through the heat exchanger 308, 408 could also be increased.

[0081] Having thus described the system and method in detail, it is to be understood that the foregoing description is not intended to limit the spirit or scope thereof. It will be understood that the embodiments of the present disclosure described herein are merely exemplary and that a person skilled in the art may make any variations and modification without departing from the spirit and scope of the disclosure. All such variations and modifications, including those discussed above, are intended to be included within the scope of the disclosure.