HVAC CASCADE HEAT PUMP

Abstract

An assembly includes a fluid conditioning system including a cascade module and an active charge compensator integrated into the fluid conditioning system. The fluid conditioning system is transformable between a first mode and a second mode. In the first mode, the fluid conditioning system includes a first vapor compression loop and a second vapor compression loop. The first vapor compression loop and the second vapor compression loop are thermally coupled at the cascade module and the second vapor compression loop is fluidly separate from the first vapor compression loop. In the second mode, the fluid conditioning system includes a single vapor compression loop. The active charge compensator is operable to control a working fluid charge within the fluid conditioning system based on the mode of operation selected from the plurality of modes.

Claims

1. An assembly comprising: a fluid conditioning system including a cascade module; an active charge compensator integrated into the fluid conditioning system; wherein the fluid conditioning system is transformable between a plurality of modes including a first mode and a second mode, in the first mode, the fluid conditioning system includes a first vapor compression loop and a second vapor compression loop, the first vapor compression loop and the second vapor compression loop being fluidly coupled at the cascade module and the second vapor compression loop being fluidly separate from the first vapor compression loop, and in the second mode, the fluid conditioning system includes a single vapor compression loop; and wherein the active charge compensator is operable to control a working fluid charge within the fluid conditioning system based on the mode of operation selected from the plurality of modes.

2. The assembly of claim 1, wherein the cascade module is fluidly connected to the fluid conditioning system during the first mode and the cascade module is not fluidly connected to the fluid conditioning system during the second mode.

3. The assembly of claim 1 wherein the active charge compensator further includes at least one flow path that fluidly couples the first vapor compression loop and the second vapor compression loop and at least one charge compensation valve associated with the at least one flow path.

4. The assembly of claim 3, wherein the active charge compensator is operable to balance the working fluid charge between the first vapor compression loop and the second vapor compression loop.

5. The assembly of claim 3, wherein the at least one flow path includes a first flow path for moving a working fluid from the first vapor compression loop to the second vapor compression loop, and a second flow path for moving the working fluid from the second vapor compression loop to the first vapor compression loop.

6. The assembly of claim 5, wherein the first flow path is fluidly connected to the first vapor compression loop at a first connection and is fluidly connected to the second vapor compression loop at a second connection, and a pressure differential exists between the first connection and the second connection.

7. The assembly of claim 6, wherein the second flow path is fluidly connected to the first vapor compression loop at the first connection and is fluidly connected to the second vapor compression loop at a third connection, and another pressure differential exists between the first connection and the third connection.

8. The assembly of claim 1, wherein the fluid conditioning system further comprises a compressor, a first heat exchanger, at least one expansion device, and a second heat exchanger and the cascade module further comprises a cascade compressor and a cascade heat exchanger.

9. The assembly of claim 1, wherein the active charge compensator further includes an expansion valve and the cascade module further includes an accumulator, the expansion valve being operable to direct a flow of working fluid to the accumulator.

10. The assembly of any claim 9, wherein the expansion valve is operable when the fluid conditioning system is in the second mode.

11. The assembly of claim 1, further comprising: at least one sensor for monitoring the working fluid charge within the fluid conditioning system; a controller operably coupled to the active charge compensator and to the at least one sensor, the controller being configured to: identify a mode of operation of the fluid conditioning system, associated with a demand on the fluid conditioning system; receive a signal indicating at least one sensed parameter of the fluid conditioning system; evaluate the working fluid charge of the first vapor compression loop and the second vapor compression loop; and operate the active charge compensator to adjust the working fluid charge based on the mode of operation and the at least one sensed parameter of the fluid conditioning system.

12. The assembly of claim 11, wherein the fluid conditioning system further includes an indoor unit and an outdoor unit, and the cascade module is selectively fluidly coupled to the indoor unit and the outdoor unit by a plurality of cascade connection valves.

13. The assembly of claim 12, wherein the controller is configured to: identify a mode of operation selected from the plurality of modes of the fluid conditioning system associated with the demand on the fluid conditioning system; and operate at least one of the plurality of cascade connection valves to initiate operation in the identified mode.

14. A method of operating a fluid conditioning system, the method comprising: receiving a demand on the fluid conditioning system; determining a mode of operation in response to the demand by comparing the demand with a heating capacity of the fluid conditioning system; and adjusting a working fluid charge within at least one vapor compression loop of the fluid conditioning system.

15. The method of claim 14, further comprising operating the fluid conditioning system in a first mode in response to the demand being greater than the heating capacity of the fluid conditioning system, wherein operating the fluid conditioning system in the first mode further comprises fluidly connecting a cascade module to the fluid conditioning system.

16. The method of claim 15, wherein during operation in the first mode, the at least one vapor compression loop includes a first vapor compression loop and a second vapor compression loop and adjusting the working fluid charge includes at least one of supplying working fluid from the first vapor compression loop to the second vapor compression loop and supplying working fluid from the second vapor compression loop to the first vapor compression loop.

17. The method of claim 16, wherein working fluid is moved between the first vapor compression loop and the second vapor compression loop in response to a pressure differential.

18. The method of claim 14, further comprising operating the fluid conditioning system in a second mode in response to the demand being less than the heating capacity of the fluid conditioning system, wherein operating the fluid conditioning system in the second mode further comprises fluidly isolating a cascade module from the fluid conditioning system.

19. The method of claim 18, wherein during operation in the second mode, adjusting the working fluid charge includes supplying working fluid from the at least one vapor compression loop to an accumulator.

20. The method of claim 14, wherein adjusting the working fluid charge within the at least one vapor compression loop of the fluid conditioning system further comprises operating at least one charge compensation valve of an active charge compensator integrated into the fluid conditioning system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

[0026] FIG. 1 is a schematic diagram of an exemplary heat pump;

[0027] FIG. 2A is a schematic diagram of a prior art heat pump in a first mode;

[0028] FIG. 2B is a schematic diagram of a prior art heat pump in a second mode;

[0029] FIG. 3 is a schematic diagram of a fluid conditioning system according to an embodiment;

[0030] FIG. 4 is a schematic diagram of the fluid conditioning system of FIG. 3 in a full load heating mode of operation according to an embodiment;

[0031] FIG. 5 is a schematic diagram of the fluid conditioning system of FIG. 3 in a partial load heating mode of operation according to an embodiment;

[0032] FIG. 6 is a schematic diagram of the fluid conditioning system of FIG. 3 in a partial load cooling mode of operation according to an embodiment;

[0033] FIG. 7 is a schematic diagram of a fluid conditioning system in a full load cooling mode of operation according to an embodiment;

[0034] FIG. 8 is a schematic diagram of a control system of a fluid conditioning system according to an embodiment;

[0035] FIG. 9A is a schematic diagram of a fluid conditioning system in a full load heating mode according to an embodiment;

[0036] FIG. 9B is a detailed view of a first cascade connection valve of the fluid conditioning system of FIG. 9A according to an embodiment;

[0037] FIG. 10A is a schematic diagram of a fluid conditioning system in a partial load heating mode according to an embodiment;

[0038] FIG. 10B is a detailed view of a first cascade connection valve of the fluid conditioning system of FIG. 10A according to an embodiment;

[0039] FIG. 11A is a schematic diagram of a fluid conditioning system in a partial load cooling mode according to an embodiment;

[0040] FIG. 11B is a detailed view of a first cascade connection valve of the fluid conditioning system of FIG. 11A according to an embodiment.

[0041] FIG. 12 is a schematic diagram of a fluid conditioning system having a cascade module and a secondary outdoor unit module fluidly connected thereto according to an embodiment; and

[0042] FIG. 13 is a schematic diagram of a fluid conditioning system having a cascade module and a secondary outdoor unit module fluidly connected thereto according to another embodiment; and

[0043] FIG. 14 is a schematic diagram of a fluid conditioning system having a cascade module thermally coupled to a second heat source according to another embodiment.

DETAILED DESCRIPTION

[0044] A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

[0045] With reference now to FIG. 1, a schematic diagram of an example of a basic vapor compression cycle of a fluid conditioning system 20, such as an air conditioning system for example, is illustrated. The vapor compression cycle includes one or more compressors 22, a first heat exchanger 24, an expansion device 26, such as an expansion valve for example, and a second heat exchanger 28. A working fluid R, such as a refrigerant for example, is configured to circulate through the vapor compression cycle, such as in a counterclockwise direction for example.

[0046] In operation, the compressor 22 receives a vapor working fluid R from the second heat exchanger 28 and compresses it to a high temperature and pressure. The relatively hot vapor working fluid R is then delivered to the first heat exchanger 24 where it is cooled and condensed to a liquid state via heat exchange relationship with a cooling medium C, such as air or water. Accordingly, when the first heat exchanger 24 receives the working fluid R output from the compressor 22, the first heat exchanger functions as a condenser. The cooled liquid working fluid R flows from the first heat exchanger 24 to the expansion device 26, such as an expansion valve for example, in which the working fluid R is expanded to a lower pressure where the temperature is reduced and the working fluid R may exist in a two-phase liquid/vapor state. From the expansion device 26, the refrigerant is provided to the second heat exchanger 28. Because heat is transferred from a secondary medium, such as air for example, to the working fluid R within the second heat exchanger 28, causing any working fluid R in the liquid phase to vaporize, the second heat exchanger 28 functions as an evaporator. From the second heat exchanger 28, the low-pressure vapor working fluid R returns to the compressor 22 so that the cycle may be repeated.

[0047] In embodiments where the fluid conditioning system 20 is a heat pump, the flow of working fluid R within the vapor compressor cycle may be reversed. In such embodiments, the working fluid R may flow clockwise from the compressor 22 to the second heat exchanger 28, the expansion device 26, and the first heat exchanger 24 sequentially. In such instances, the working fluid R within the second heat exchanger 28 is cooled and condensed to a liquid state and the working fluid R within the first heat exchanger is heated to form a low-pressure vapor. Accordingly, when operating in this reverse flow direction, the second heat exchanger 28 functions as the condenser and the first heat exchanger 24 functions as the evaporator of the vapor compression cycle.

[0048] With reference now to FIGS. 2A-2B, a schematic diagram of a fluid conditioning system 20 configured as a heat pump is shown. In the illustrated, non-limiting embodiment, the heat pump 20 includes a first, indoor unit or portion 30 associated with a building to be conditioned and a second outdoor unit or portion 32 positioned outside of the building. The first indoor unit 30 may be arranged within the building to be conditioned, or alternatively, may be arranged at an exterior of the building, such as at a rooftop thereof. It should be understood that embodiments where the fluid conditioning system 20 is installed in a single casing located partially or completely inside or outside of the building, such as a rooftop unit for example, are also within the scope of the disclosure.

[0049] As shown, at least one compressor 22 is located within the outdoor unit 32. The one or more compressors 22 may be any suitable single or multistage compressor, including, but not limited to a screw compressor, reciprocating compressor, centrifugal compressor, scroll compressor, rotary compressor, or axial-flow compressor. The compressor(s) 22 may be fixed speed or variable speed and may be driven by an electrically powered motor, or another suitable energy source.

[0050] The first heat exchanger 24 is arranged within the indoor unit 30 and is directly or indirectly fluidly coupled to the one or more compressors 22. The first heat exchanger 24 may be any suitable type of heat exchanger configured to transfer heat between a working fluid R and air or another medium. For example, the first heat exchanger 24 may include one or more coils of thermally conductive material, such as copper, aluminum, alloys thereof, or combinations thereof. In other embodiments, the first heat exchanger 24 may be a round-tube plate fin, microchannel, shell-and tube heat exchanger, a printed circuit heat exchanger, a plate-fin heat exchanger, or any combination thereof. In the illustrated, non-limiting embodiment, the air or other medium is moved (drawn, blown, or pumped) over the first heat exchanger 24 via a first movement mechanism 34, such as an axial or centrifugal fan for example.

[0051] The fluid conditioning system 20 includes at least one expansion device 26. Although a single expansion device 26 is illustrated, it should be understood that embodiments having a separate indoor expansion device positioned within the indoor portion and an outdoor expansion device positioned within the outdoor portion are also contemplated herein. The first heat exchanger 24 is fluidly coupled to the expansion device 26.

[0052] The second heat exchanger 28 is arranged within the outdoor unit 32 of the fluid conditioning system 20 and is also fluidly coupled to the expansion device 26. In embodiments including a separate indoor expansion device 26b and outdoor expansion device 26a, the first heat exchanger 24 is fluidly coupled to the indoor expansion device 26b and the second heat exchanger 28 is fluidly coupled to the outdoor expansion device 26a. In some embodiments, working fluid R is only configured to flow through one of the expansion devices 26a, 26b in each direction of flow through the refrigeration circuit. In other embodiments, the working fluid R may be configured to flow through both expansion devices 26a, 26b in series, regardless of a direction of flow; however, the working fluid R will only be expanded in one of the expansion devices, such as the downstream expansion device relative to the direction of flow, and the flow will be unrestricted in the other expansion device.

[0053] Similar to the first heat exchanger 24, the second heat exchanger 28 may be any suitable type of heat exchanger configured to transfer heat between a working fluid R and air or another medium. In the illustrated, non-limiting embodiment, the second heat exchanger 28 is disposed about the outer extent of the outdoor unit 32. However, embodiments where the second heat exchanger 28 is arranged at another location, such as within or proximal to the outdoor unit 32 are also contemplated herein.

[0054] The second heat exchanger 28 may have any suitable configuration. For example, the second heat exchanger 28 may include one or more coils of thermally conductive material, such as copper, aluminum, alloys thereof, or combinations thereof. In other embodiments, the second heat exchanger 28 may be a round-tube plate fin heat exchanger, microchannel heat exchanger, shell-and tube heat exchanger, a printed circuit heat exchanger, a plate-fin heat exchanger, or any combination thereof.

[0055] In the illustrated, non-limiting embodiment, the outdoor unit 32 includes a second movement mechanism 36, such as a fan assembly for example, to move air or another medium over the second heat exchanger 28. The second movement mechanism 36 may be arranged adjacent to a top 38 of the outdoor unit 32, as shown, or may be positioned near a bottom 40 of the outdoor portion, or at any point between the top 38 and the bottom 40 to push or pull air through the outdoor portion.

[0056] The fluid conditioning system 20 additionally includes a four-way valve 42 configured to redirect the flow of working fluid R therein. In the illustrated embodiment, the four-way valve 42 is arranged within the outdoor unit 32 and includes a fluidly separate first flow path and second flow path. In a first state, as shown in FIG. 2A, the first flow path fluidly connects an outlet of the one or more compressors 22 to the first heat exchanger 24, and the second flow path fluidly connects the second heat exchanger 28 to an inlet of the one or more compressors 22. In a second state, the first flow path fluid connects the outlet of the one or more compressors 22 to the second heat exchanger 28 and the second flow path fluidly connects the first heat exchanger 24 to the inlet of the one or more compressors 22 (FIG. 2B). It should be understood that the fluid conditioning system 20 illustrated and described herein is intended as an example only and that a fluid conditioning system having another configuration and/or additional components arranged along the fluid flow path are also within the scope of the disclosure.

[0057] The fluid conditioning system may be operable in a heating mode, as shown in FIG. 2A. When the four-way valve 42 is in the first state, working fluid R is configured to flow through the closed refrigeration circuit from the compressor 22 to the first heat exchanger 24 acting as a condenser. Within the first heat exchanger 24, heat is transferred from the working fluid R to the air moving across the first heat exchanger 24 by the first movement mechanism 34. This warmed air may be used to heat one or more areas to be conditioned within the building. The partially or fully condensed liquid working fluid R is provided from the first heat exchanger 24 to the expansion device 26 where the pressure is reduced causing the working fluid R to be expanded and cooled to a temperature below the ambient temperature. Within the second heat exchanger 28, heat is transferred to the working fluid R from the air moving across the second heat exchanger 28 by the second movement mechanism 36. This heat causes the liquid portions of the working fluid R to evaporate to a gaseous phase. From the second heat exchanger 28, the working fluid R is returned to the compressor 22 via the four-way valve 42.

[0058] During normal operation of the fluid conditioning system in a heating mode, frost can accumulate on the second heat exchanger 28. When frost accumulates on the second heat exchanger 28, the frost diminishes heat transfer from the air to the heat exchanger and therefore provides undesirable insulating properties to the heat exchanger. The undesirable insulating properties result in an increase in the temperature difference between the temperature of the air and the temperature of the heat exchanger. As the extent and thickness of frost increases, the degree of insulating properties of the frost increases. Accordingly, the temperature of the second heat exchanger 28 will continue to decrease indefinitely as frost continues to accumulate.

[0059] As frost accumulates on the second heat exchanger 28 and the operating temperature of the second heat exchanger 28 decreases, the operating temperature of the working fluid R within the second heat exchanger 28 decreases as a result. Given a fixed amount of superheat, the density of the vapor working fluid R leaving the second heat exchanger 28 decreases as the temperature of the vapor decreases. Decreasing vapor density for a given volume flow results in decreasing mass flow, and the heating capacity of the fluid conditioning system 20 decreases. Therefore, the extent and thickness of the presence of frost will directly relate to a decrease in mass flow and heating capacity.

[0060] To eliminate, or at least mitigate, this frost, the fluid conditioning system 20 may transition to a defrost mode, such as by switching the four-way valve 42 to the second state. In the second state, shown in FIG. 2B the direction of flow of working fluid R through the closed circuit is reversed. Accordingly, the warm, high pressure working fluid R output from the at least one compressor 22 is routed to the second heat exchanger 28 such that the second heat exchanger 28 functions as a condenser rather than as an evaporator. As the second heat exchanger 28, heat is rejected from the fluid, thereby melting the frost to prepare the second heat exchanger 28 for operation as an evaporator once the system transforms back to a heating mode. In the defrost mode, the second movement mechanism 36 may be disabled to prevent air movement through the second heat exchanger 28 thus enabling the temperature of the second heat exchanger 28 to increase.

[0061] From the second heat exchanger 28, the working fluid R is expanded in an expansion device 26, such as the indoor expansion device (not shown), and then is delivered to the first heat exchanger 24, which is configured to operate as an evaporator. Within the first heat exchanger 24, the working fluid R can absorb heat from the medium moving across the first heat exchanger 24 via the first movement mechanism 34. In an embodiment, the fluid conditioning system 20 includes an auxiliary heater 44 configured to heat the cool air output from the first heat exchanger 24 during a defrost cycle to meet the heating demands of the area being conditioned. From the first heat exchanger 24, the working fluid R is returned to the compressor 22 via the four-way valve 42.

[0062] With reference now to FIGS. 3-8, another exemplary fluid conditioning system 20 according to an embodiment is illustrated. In an embodiment, the fluid conditioning system 20 is similar to the heat pump described above with respect to FIGS. 2A and 2B; however, the fluid conditioning system 20 may additionally include or may be connectable to a cascade module 50 selectively operable to extend the operating conditions of the fluid conditioning system 20. In some embodiments, the cascade module 50 is an integral portion of the fluid conditioning system 20. In such embodiments, the indoor unit 30, outdoor unit 32, and cascade module 50 may be packaged as a single unit. In other embodiments, the cascade module 50 is separate module that can be attached to and removed from both new and existing fluid conditioning systems.

[0063] When installed, the cascade module 50 may be fluidly coupled to at least a portion of the fluid conditioning system 20. For example, the cascade module 50 may be fluidly coupled to the outdoor unit 32, to the indoor unit 30, or both. Further, the cascade module 50 may be continuously fluidly connected to the fluid conditioning system 20, or alternatively, may be selectively fluidly connected to the fluid conditioning system 20.

[0064] The cascade module 50 may include a plurality of components. In the illustrated, non-limiting embodiment, the components include a cascade compressor 52, and a cascade heat exchanger 56 (see FIGS. 4 and 6). Although not shown, in an embodiment, the cascade module 50 may additionally include a four-way valve, such as a reversing valve. However, embodiments including only a portion of these components, additional components, and/or alternative components are also within the scope of the disclosure. It should be appreciated that the cascade module 50 may additionally include one or more conduits operable to fluidly connect the components of the cascade module 50 to one another or to another portion of the heat pump 20. Further, the cascade module 50 may include one or more conduits configured to cooperate with or form part of a conduit that defines a direct flow path between the indoor unit 30 and the outdoor unit 32.

[0065] In some embodiments, the plurality of components associated with the cascade module 50 (i.e., cascade compressor 52 and cascade heat exchanger 56 to be described in more detail below) are integrated or packaged within a single housing or unit, illustrated schematically at 60 in FIG. 3. It should be appreciated that the cascade module 50 may further include conduits, flow control devices, and any other mechanisms associated with directing and controlling the fluid flow provided to the components of the cascade module 50, and/or the fluid flow that bypasses the components of the cascade module 50. It should be appreciated that some valves or other flow control devices operable to direct the flow to the cascade module 50 or to bypass the cascade module 50 may be arranged within the housing 60 containing the cascade module 50, but in some embodiments, may not be considered part of the cascade module 50. In alternative embodiments, such flow control devices may be located separately from the housing 60 of the cascade module 50.

[0066] In such embodiments, the housing 60 is located at, and in some embodiments is mechanically affixed to, a portion of the outdoor unit 32 or a portion of the indoor unit 30. Further, in other embodiments, the components associated with the cascade module 50 may be separated into a plurality of packages or units. In such embodiments, the units may be mounted at the same location about the fluid conditioning system 20, such as the outdoor unit 32 or the indoor unit 30 for example, or may be split between the indoor unit 30 and the outdoor unit 32. Further, embodiments where a housing 60 including at least a portion of the cascade module 50, and in some embodiments the entirety of the cascade module, is mounted at another location remote from both the indoor unit 30 and outdoor unit 32 are also contemplated herein. For example, the fluid conditioning system 20 may be associated with a building, and the cascade module 50 may be positioned at a different location about the building than the indoor unit 30.

[0067] When the cascade module 50 is fluidly connected to the fluid conditioning system 20, the overall capacity of the heat pump 20 may be increased while improving an overall sizing envelope, such as when the outdoor and indoor temperature conditions have high temperature lift for example. As used herein, the term fluidly connected when used relative to the cascade module 50 is intended to describe embodiments where at least one of the cascade compressor 52 and the cascade heat exchanger 56 of the cascade module 50 is configured to receive and condition a flow of working fluid R. In an embodiment, such as shown in FIGS. 4 and 6 for example, when the cascade module 50 is fluidly connected to the fluid conditioning system 20, the fluid conditioning system 20 is transformed from having a single vapor compression loop to having a plurality of fluidly separate vapor compression loops. For example, the fluid conditioning system 20 may include two fluidly separate compression loops, identified at VC1 and VC2 respectively, thermally coupled to one another. The vapor compression loops VC1, VC2 may be thermally coupled at a component of the cascade module 50. As will be described in more detail below, in an embodiment, the two vapor compression loops VC1, VC2 are thermally coupled to one another at the cascade heat exchanger 56 of the cascade module 50 during one or more modes of operation. Although only two vapor compression loops VC1, VC2 are illustrated and described herein, it should be understood that embodiments where the fluid conditioning system is transformable to a configuration having more than two fluidly separate vapor compression loops are also within the scope of the disclosure.

[0068] It should be appreciated that in embodiments where the cascade module 50 is not fluidly connected to the fluid conditioning system 20 or is considered fluidly isolated from the fluid conditioning system 20, the working fluid R of the fluid conditioning system 20 is not provided to one or more components of the cascade module 50 operable to condition the working fluid R therein. However, it should be appreciated that the cascade module 50 may remain mechanically connected to the fluid conditioning system 20 when the cascade module 50 is fluidly connected to and when the cascade module 50 is not fluidly connected to the fluid conditioning system 20.

[0069] The fluid conditioning system 20 is operable in a plurality of modes. For example, the modes of operation may include but are not limited a full load heating mode (FIG. 4), a partial load heating mode (FIG. 5), a full load cooling mode/turbo defrost mode (FIG. 7), a partial load cooling mode (FIG. 6). With reference to FIG. 4, a schematic diagram of the fluid conditioning system 20 in a full load heating mode is illustrated. In the full load heating mode, the cascade module 50 is fluidly connected to the fluid conditioning system 20. As shown, the four-way valve 42 is in a first position or state such that the working fluid R within the first vapor compression loop VC1 is configured to flow from the compressor 22 of the outdoor unit 32 to a first pass 62 of the cascade heat exchanger 56 of the cascade module 50. The first pass 62 of the cascade heat exchanger 56 functions as a condenser causing the working fluid R of the first vapor compression loop VC1 to be cooled therein. The cool liquid working fluid R output from the first pass 62 of the cascade heat exchanger 56 may be provided to the expansion device 26a and to the second heat exchanger 28 of the outdoor unit 32 operable as an evaporator, in series. The vapor working fluid R output from the evaporator 28 is then returned to a suction inlet of the compressor 22 via the four-way valve 42 to repeat the cycle.

[0070] In an embodiment, the fluid conditioning system 20 includes at least one accumulator or receiver 70. In such embodiments, liquid working fluid R may be collected within the accumulator 70. As shown, the accumulator 70 may be arranged downstream from the second heat exchanger 28, and in some embodiments the four-way valve 42, and/or directly upstream from the suction inlet of the compressor 22 relative to the flow of the working fluid R. During operation in a heating mode, the accumulator 70 acts as a storage tank for excess liquid working fluid R to ensure that only a vaporized working fluid R is provided to the compressor 22. It should be appreciated that embodiments of the fluid conditioning system 20 that do not include the accumulator 70 are also contemplated herein.

[0071] The working fluid R within the second vapor compressor loop VC2 is configured to flow from the outlet of the cascade compressor 52 of the cascade module 50 to the first heat exchanger 24. In the full load heating mode, the first heat exchanger 24 functions as a condenser, thereby cooling the working fluid R to a liquid. From the first heat exchanger 24, the working fluid R of the second vapor compression loop VC2 flows to an expansion device, such as the expansion device 26b arranged within the indoor unit 30 or an expansion device 26c within the cascade module 50, and then to a second pass 64 of the cascade heat exchanger 56. The second pass 64 of the cascade heat exchanger 56 is operable as an evaporator such that heat from the working fluid R within the first pass 62 (from the first compression loop VC1) of the cascade heat exchanger 56 is transferred to the working fluid R within the second pass 64, thereby causing the working fluid R within the second pass 64 to at least partially vaporize. The working fluid R output from the second pass 64 has a higher vapor quality and enthalpy than the working fluid R provided to the second pass 64 and is returned to the inlet of the cascade compressor 52 of the cascade module 50 to repeat the cycle.

[0072] In the illustrated, non-limiting embodiment, the cascade module 50 additionally includes an accumulator or receiver 72. As shown, the accumulator 72 may be positioned directly upstream from the inlet of the cascade compressor 52 and during operation of the cascade module 50 in a heating mode, may accumulate excess working fluid R therein. It should be appreciated that embodiments of the cascade module 50 that do not include the accumulator 72 are also within the scope of the disclosure.

[0073] A schematic diagram of the fluid conditioning system 20 including a cascade module 50 in a partial load heating mode is illustrated in FIG. 5. In the partial load heating mode, although the cascade module 50 may be mechanically connected to the fluid conditioning system 20, the cascade module 50 is not fluidly connected to and does not form a portion of the vapor compression cycle of the fluid conditioning system 20. Operating the system in a partial load heating mode may be achieved by opening valve V2a, turning off the cascade compressor 52, and closing the expansion valve 26. When the cascade module 50 is not fluidly connected to the fluid conditioning system 20, none of the working fluid R of the fluid conditioning system 20 is provided to the cascade compressor 52 or the cascade heat exchanger 56 of the cascade module 50. However, it should be understood that working fluid may be configured to flow or pass through one or more conduits located within the cascade module 50 as the working fluid flows between the indoor unit 30 and the outdoor unit 32.

[0074] In such embodiments where the cascade module 50 is off and therefore is not fluidly connected to the fluid conditioning system 20, the fluid conditioning system 20 only has a single vapor compression loop. As shown, the four-way valve 42 is in a first position such that working fluid is configured to flow from the outlet of the compressor 22 of the outdoor unit 32 to the first heat exchanger 24. The condensed working fluid R output from the first heat exchanger 24 may then be provided to the expansion device 26a and to the second heat exchanger 28 of the outdoor unit 32 operable as an evaporator, in series. The working fluid R vapor output from the second heat exchanger 28 is then returned to the suction port or inlet of the compressor 22 to repeat the cycle and any liquid working fluid R may be collected within the accumulator 70.

[0075] With reference now to FIG. 6, a schematic diagram of operation of the fluid conditioning system 20 in a partial load cooling mode is illustrated. In the partial load cooling mode, the cascade module 50 is not fluidly connected to and does not form a portion of the vapor compression cycle of the fluid conditioning system 20. In a cooling mode, the four-way valve 42 is in the second position. As a result, working fluid R is configured to flow from the outlet of the compressor 22 of the outdoor unit 32 to the second heat exchanger 28. The condensed working fluid R output from the second heat exchanger 28 is provided to an expansion device, such as the expansion device 26b arranged within the indoor unit 30. From the expansion device 26, the working fluid R is provided to the first heat exchanger 24, where the working fluid R is heated. The vapor working fluid R output from the first heat exchanger 24 is then returned to an inlet of the compressor 22 via the four-way valve 42. As the working fluid R is provided from the first heat exchanger 24 to the primary inlet of the compressor 22, the working fluid passes through the accumulator 70 and any liquid working fluid R is collected therein.

[0076] With reference now to FIG. 7, a schematic diagram of the fluid conditioning system 20 in a full load cooling mode and/or a turbo defrost mode is illustrated. In the illustrated non-limiting embodiment of the fluid conditioning system 20, the cascade module 50 is includes another four-way valve 54 operable to reverse the flow of the working fluid R within the second vapor compression loop VC2. Accordingly, the four-way valve 54 may be in a first position associated with a first direction of flow during operation in a full load heating mode and may be in a second position associated with an opposite, second direction of flow during operation in a full load cooling mode and/or a turbo defrost mode. However, it should be understood that in some embodiments, the cascade module 50 may not include this reversing valve 54, and therefore is not operable in a cooling mode.

[0077] Similar to the full load heating mode, during operation in the full load cooling mode and/or a turbo defrost mode, the cascade module 50 is fluidly coupled to the remainder of the fluid conditioning system 20 resulting in separate first and second vapor compression loops, VC1, VC2. As shown, both four-way valves 42 and 54 are in a second position such that the flow within each vapor compression loop, VC1, VC2 is reversed relative to the flow in the full load heating mode. The working fluid R of the first vapor compression loop VC1 is configured to flow from the outlet of the compressor 22 of the outdoor unit 32 to the second heat exchanger 28. Within the second heat exchanger 28, the working fluid R is cooled and condensed into a liquid. The condensed working fluid R output from the second heat exchanger 28 may then be provided to an expansion device, such as the expansion device 26a of the outdoor unit 32. From the expansion device 26a, the working fluid R may be provided to the first pass 62 of the cascade heat exchanger 56 of the cascade module 50. Heat is transferred to the working fluid R within the first pass 62 causing the working fluid R of the first vapor compression loop VC1 to vaporize. The vapor working fluid R output from the first pass 62 of the cascade heat exchanger 56 is then returned to an inlet of the compressor 22 to repeat the cycle. As the working fluid R is provided from the cascade heat exchanger 56 to the primary inlet of the compressor 22, the working fluid R passes through the accumulator 70 such that any liquid working fluid R is collected therein.

[0078] Similarly, working fluid R within the second vapor compressor loop VC2 is configured to flow from the cascade compressor 52 of the cascade module 50 to the second pass 64 of the cascade heat exchanger 56. In the full load cooling mode, heat from the working fluid R within the second pass 64 of the cascade heat exchanger 56 transfers to the working fluid R within the first pass 62 thereof. As a result, the working fluid R within the second pass 64 of the cascade heat exchanger 56 is cooled. From the cascade heat exchanger 56, the working fluid R of the second vapor compression loop VC2 is provided to an expansion device. In the illustrated, non-limiting embodiment, the flow is provided to an expansion device 26c located within the housing 60 of the cascade module 50. However, embodiments where the flow is provided to an expansion device 26b located within the indoor unit 30 are also contemplated herein. From the expansion device 26c, the working fluid R is provided to the first heat exchanger 24 within the indoor unit 30. In such embodiments, the first heat exchanger 24 is configured as an evaporator. From the first heat exchanger 24, the working fluid R of the second vapor compression loop VC2 is returned to the cascade compressor 52 to repeat the cycle. As the working fluid R is provided from the first heat exchanger 24 to the suction inlet of the cascade compressor 52, the working fluid R may pass through the accumulator 72 such that any liquid working fluid R is collected therein.

[0079] The mode of operation of the fluid conditioning system 20 may be selected based on at least one parameter of the fluid conditioning system 20 and/or of the ambient atmosphere. For example, the mode may be selected based on the demand put on the system 20, the load or set point of the area being conditioned by the fluid conditioning system 20, the current temperature of the area being conditioned, and/or the outdoor air temperature. When the fluid conditioning system 20, absent the cascade module 50, is capable of meeting the demand of the system, such as during a partial load heating mode (FIG. 5) or partial load cooling mode (FIG. 6), the cascade module 50 need not be fluidly connected to the vapor compression cycle, and therefore may be considered off or non-operational. Accordingly, one or more valves, such as one or more cascade connection valves V1, V2, or valve V3 for example, may be transformed between a first configuration, such as an open configuration, and a second configuration, such as a closed configuration or another suitable configuration for example, to selectively couple the cascade module 50 to the fluid conditioning system 20. Transformation of the plurality of cascade connection valves V1, V2 to the closed configuration may fluidly disconnect or isolate the cascade module 50, such as the cascade compressor 52 and the cascade heat exchanger 56 from the remainder of the fluid conditioning system 20.

[0080] In the illustrated, non-limiting embodiment, a first cascade connection valve V1 is arranged along a flow path extending between the indoor unit 30 and the outdoor unit 32, such as between the four-way valve 42 and the first heat exchanger 24 at a location directly adjacent to a fluid connection with the cascade heat exchanger 56. In embodiments where the fluid conditioning system 20 is operating in a partial load (heating or cooling) mode, the working fluid bypasses the cascade heat exchanger 56 and is instead provided to the downstream indoor unit 30 via the first cascade connection valve V1. In some embodiments, the first cascade connection valve V1 is a solenoid valve having an integral check valve feature. However, embodiments where the first cascade connection valve V1 includes a separate solenoid valve V1a and a bypass conduit 74 extending from directly upstream of the solenoid valve V1a to directly downstream of the solenoid valve V1a and including a check valve CV1, as shown in FIG. 4, are also contemplated herein. In the illustrated, non-limiting embodiment, the working fluid R is configured to flow through one of the bypass conduits 74 and the solenoid valve V1a during operation in a partial heating mode and the other of the bypass conduit 74 and the solenoid valve V1a during operation in a partial cooling mode. As shown, in a partial load heating mode, the working fluid R may be provided from the outdoor unit 32 directly to the downstream indoor unit 30 via the bypass conduit 74 and check valve CV1 of the first cascade connection valve V1. Similarly, when the fluid conditioning system 20 is operating in a partial load cooling mode, the working fluid R may be provided from the indoor unit 30 to the downstream outdoor unit 32 via the solenoid valve V1a of the first cascade connection valve V1.

[0081] As shown, a valve V3 separate from the first cascade connection valve V1 may be arranged at or upstream from an inlet of the first pass 62 of the cascade heat exchanger 56, such as in parallel with the valve V1a, relative to a flow of working fluid in a heating mode. When the fluid conditioning system 20 is operating in a partial load heating mode, this valve V3 is closed, thereby preventing the flow of working fluid R from the four-way valve 42 to the cascade heat exchanger 56.

[0082] A second cascade connection valve V2, similar to the first cascade connection valve V1, may be arranged along a fluid flow path extending between the indoor unit 30 and the outdoor unit 32, such as between the expansion device 26a and the first heat exchanger 24, or between the expansion valves 26a, 26b at a location proximate a fluid connection with the cascade heat exchanger 56. In some embodiments, the second cascade connection valve V2 is a solenoid valve having an integral check valve feature. However, embodiments where the second cascade connection valve V2 includes a solenoid valve V2a and a bypass conduit 75 extending in parallel with the solenoid valve V2a to directly downstream of the solenoid valve V2a and including a check valve CV2 therein, as shown in FIG. 4, are also contemplated herein. In the illustrated, non-limiting embodiment, the working fluid R is configured to flow through one of the bypass conduits 75 and the solenoid valve V2a during operation in a partial heating mode and the other of the bypass conduit 75 and the solenoid valve V2a during operation in a partial cooling mode. As shown, in a partial load heating mode, the working fluid R may be provided from the indoor unit 30 to the downstream outdoor unit 32 via the solenoid valve V2a of the second cascade connection valve V2. Similarly, when the fluid conditioning system 20 is operating in a partial load cooling mode, the working fluid R may be provided from the outdoor unit 32 directly to the downstream indoor unit 30 via the bypass conduit 75 and the check valve CV2 of the second cascade connection valve V2.

[0083] In some embodiments, such as embodiments where the cascade module is not operable in a cooling mode, a check valve CV3 may be disposed directly downstream from an outlet of the first pass 62 of the cascade heat exchanger 56 relative to a direction of flow of the working fluid R during operation in a heating mode. The check valve CV3 may be configured to prevent the flow of working fluid R output from the second heat exchanger 28 from entering the cascade heat exchanger 56, such as during operation in a partial load mode.

[0084] In embodiments where the fluid conditioning system 20, without the cascade module 50, is not able to meet the demands on the system, valves such as the first and second cascade connection valves V1 and V2 and valve V3 for example, will be operated to fluidly connect the cascade module 50 to the remainder of the system 20, thereby increasing the capacity of the fluid conditioning system 20. In an embodiment, fluidly connecting the cascade module 50 to the indoor and outdoor units 30, 32 occurs by closing both the first and second cascade connection valves V1 and V2, and by opening valve V3 at the inlet of the first pass 62 of the cascade heat exchanger 56. When the first cascade connection valve V1 is closed and the valve V3 is open, the flow from the four-way valve 42 of the outdoor unit 32 during operation in the heating mode is directed to first pass of the cascade heat exchanger 56. Similarly, when valve V2 is closed, working fluid R is configured to flow between the first heat exchanger 24 of the indoor unit 30 and the cascade heat exchanger 56.

[0085] With reference to FIG. 8, in an embodiment, the fluid conditioning system 20 includes a control system 80 configured to control operation of the fluid conditioning system 20 in one of the plurality of modes. The control system 80 of the fluid conditioning system 20 includes a controller C having one or more of a microprocessor, microcontroller, application specific integrated circuit (ASIC), or any other form of electronic controller known in the art. The controller C is operably coupled to the compressor 22 and/or the cascade compressor 52, at least one four-way valve, such as a reversing valve 42, the one or more cascade connection valves V1, V2, solenoid valve V3, and any other suitable components, such as fan 34, auxiliary heater 44, and/or the expansion device 26a, 26b, 26c.

[0086] In an embodiment, the control system 80 additionally includes at least one sensor S operable to monitor one or more operating parameters or operating conditions (referred to collectively herein as parameters) of the fluid conditioning system 20 to determine the mode of operation of the fluid conditioning system 20 at any given time. The at least one sensor S may be configured to continuously monitor and communicate a respective parameter to the controller C, or alternatively, may be configured to intermittently monitor and communicate a respective parameter to the controller C, such as via one or more signals.

[0087] Although the configuration of the vapor compression loops VC1, VC2 of the fluid conditioning system 20 are the same for both a full load cooling mode and a turbo defrost mode, the conditions required to initiate operation in the turbo defrost mode may vary from those that initiate operation of the fluid conditioning system 20 in the full load cooling mode. In an embodiment, the turbo defrost mode may be initiated in response to the running time of the fluid conditioning system 20 in a heating mode. In other embodiments, the turbo defrost mode is initiated in response to the heating capacity of the second heat exchanger 28 during a heating mode. A comparison of the heating capacity of the second heat exchanger 28 during operation of the heating mode and the heating capacity of the second heat exchanger 28 when no frost is present will indicate the reduction in heating capacity due to frost accumulation on the second heat exchanger 28. It should be appreciated that several parameters of the fluid conditioning system 20 can be used to observe a reduction in heating capacity. Heating capacity relates directly to mass flow of the working fluid R and occurs primarily with working fluid phase change (i.e., when it condenses into a liquid or evaporates into a vapor).

[0088] In an embodiment, the at least one sensor S correlates to or is associated with determining the capacity of the second heat exchanger 28. The controller C may be configured to compare the monitored parameter with a respective threshold to determine when to initiate or trigger operation in the defrost mode. As used herein, the term monitored parameter is intended to include parameters or operating conditions that are measured via one or more sensors, or alternatively, parameters or operating conditions that are calculated using the monitored parameters or operating conditions.

[0089] The at least one sensor S of the control system 80 may include a temperature sensor. A temperature sensor may be used to monitor one or more or an ambient temperature surrounding the outdoor unit 32, a temperature of the discharge air output from the second heat exchanger 28, and a temperature of the working fluid R circulating within the fluid conditioning system 20, and a temperature of the second heat exchanger 28 itself. In embodiments where the at least one sensor S includes a temperature sensor, the temperature sensor may be any suitable device, including but not limited to a thermistor, thermocouple, thermostat, infrared sensor, etc. Alternatively, or in addition, the at least one sensor S may be a pressure sensor, for example operable to measure a reduction in pressure of the working fluid R. A pressure sensor consisting of any suitable device, including but not limited to a strain gage bridge, for example is within the scope of the disclosure. In an embodiment, the at least one sensor S includes a mass flow sensor. It should be appreciated that the temperature, pressure, and mass flow rate described herein are intended as exemplary parameters only, and that a reduced heating capacity of the fluid conditioning system 20 can be detected by observing a reduction of some other operating parameter indicative of a reduced heat transfer at the second heat exchanger 28. Further, the one or more parameters monitored by the at least one sensor S may be used to determine if the charge of a vapor compression loop of the fluid conditioning system 20 is too high or too low.

[0090] With continued reference to FIGS. 4-8, during transformation of the fluid conditioning system 20 from a partial load configuration (where the cascade module 50 is not fluidly connected to the indoor and outdoor units 30, 32) having a single vapor compression loop to a full load configuration (where the cascade module 50 is fluidly connected to the indoor and outdoor units 30, 32) having two separate vapor compression loops, control may be performed to ensure that the working fluid charge within each respective vapor compression loop VC1, VC2 is sufficient to optimize operation of the fluid conditioning system 20. In an embodiment, the fluid conditioning system 20 includes an active charge compensator, represented generally at 100, that selectively fluidly connects the plurality of fluidly separate vapor compression loops of the fluid conditioning system 20. For example, the charge compensator is operable to fluidly couple the first vapor compression loop VC1 to the fluidly separate second vapor compression loop VC2 to balance the working fluid charge therebetween. Although the active charge compensator is illustrated and described with respect to a fluid conditioning system 20 having two separate vapor compression loops VC1, VC2, it should be understood that the active charge compensator may be adapted for use with systems having additional, fluidly separate vapor compression loops.

[0091] The active charge compensator 100 defines at least one flow path extending between and fluidly connecting different areas of the fluid conditioning system 20 having different pressures. In the illustrated, non-limiting embodiment, the active charge compensator 100 includes at least one charge compensation flow path, such as a first charge compensation flow path extending between a first connection point 102 associated with the first vapor compression loop VC1 and a second connection point 104 associated with the second vapor compression loop VC2. In some embodiments, the active charge compensator 100 may similarly include a second charge compensation flow path extending between the first connection point 102 associated with the first vapor compression loop VC1 and a third connection point 106 associated with the second vapor compression loop VC2. In such embodiments, the second and third connection points 104, 106 may be arranged in parallel relative to the first connection point 102. Although the first connection point 102 is illustrated and described herein as being fluidly connected to both the second connection point 104 and the third connection point 106 at the second vapor compression loop VC2, it should be understood that embodiments where another connection point at the first vapor compression loop VC1, distinct from the first connection point 102, is fluidly connected to either the second connection point 104 or the third connection point 106 at the second vapor compression loop VC2 are also contemplated herein.

[0092] The first connection point 102 of the active charge compensator 100 may be arranged between the first pass 62 of the cascade heat exchanger 56, or the check valve CV3 downstream therefrom, and the expansion device 26a. The second connection point 104 of the active charge compensator 100 may be positioned along the fluid flow path extending between the first heat exchanger 24 and the cascade heat exchanger 56. As shown in FIG. 4, the second connection point 104 may be positioned downstream from an outlet of the first heat exchanger 24 and upstream from an inlet of the second pass 64 of the cascade heat exchanger 56 relative to a flow of the working fluid R during operation in a heating mode. In some embodiments, the second connection point 104 may be located upstream from an expansion device 26c of the cascade module 50 during operation in a heating mode. The third connection point 106 may alternatively or additionally be positioned downstream from an outlet of the first heat exchanger 24 and upstream from an inlet of the second pass 64 of the cascade heat exchanger 56 relative to a flow of the working fluid when in a heating mode. In some embodiments, the second connection point 104 may be located downstream from an expansion device 26c of the cascade module 50 during operation in a heating mode.

[0093] As previously described, the cascade module 50 may include a accumulator 72 located upstream from and fluidly connected to a suction inlet of the cascade compressor 52. Although not shown, in some embodiments, the third connection point 106 may alternatively be arranged at or directly upstream from the accumulator 72. In such embodiments, the second charge compensation flow path extends between the third connection point 106 upstream from the accumulator 72 of the second vapor compression loop VC2 to a connection with the first vapor compression loop VC1, such as the first connection point 102 for example.

[0094] At least one charge compensation valve may be associated with one of more of the charge compensation flow paths of the active charge compensator. A first charge compensation valve CVV1 may be associated with the first charge compensation flow path to selectively control flow of a working fluid therethrough. For example, the first charge compensation valve CVV1 may be arranged proximate the second connection point 104. In the illustrated, non-limiting embodiment, the second connection point 104 is located directly upstream from the solenoid valve V2a of the second cascade connection valve V2, and the solenoid valve V2a may be operable as the first charge compensation valve CVV1 associated with the first charge compensation flow path. However, embodiments where the second connection point 104 is further upstream from the second cascade connection valve V2 or at least a portion thereof are also contemplated herein. In such embodiments, the first charge compensation valve is separate from the second cascade connection valve V2. Alternatively, or in addition, a second charge compensation valve CCV2 may similarly be associated with the second charge compensation flow path to selectively control the flow of a working fluid R therethrough. In an embodiment, the second charge compensation valve CCV2 is located proximate the third connection point 106. In an embodiment, the second charge compensation valve CCV2 is a solenoid valve having an integral check valve. However, any suitable valve configuration is contemplated herein.

[0095] Opening of the first charge compensation valve CCV1 allows working fluid R to flow between the second connection point 104 and the first connection point 102 via the first charge compensation flow path. Opening of the second charge compensation valve CCV2 similarly allows working fluid to flow between the first connection point 102 and the third connection point 106 via the second charge compensation flow path. The pressure differential between the first connection point 102 and the second connection point 104, and the pressure differential between the first connection point 102 and the third connection point 106 is sufficient to move the working fluid R between the two vapor compression loops VC1, VC2.

[0096] When the fluid conditioning system 20 is operating in a full load heating or cooling mode, both the first and second cascade connection valves V1, V2 are closed, thereby forming the two separate vapor compression loops. To move working fluid from the second vapor compression loop VC2 to the first vapor compression loop VC1, the first compensation valve CCV1 is opened and the second charge compensation valve CCV2 is closed. In this configuration, the first charge compensation flow path is fluidly connected to both vapor compression loops VC1, VC2. The pressure differential between the first connection point 102 and the second connection point 104 will cause working fluid to flow from the second vapor compression loop VC2 to the first vapor compression loop VC1.

[0097] To move working fluid from the first vapor compression loop VC1 to the second vapor compression loop VC2, the second charge compensation valve CCV2 is opened and the first charge compensation valve CCV1 is closed. In this configuration, the second charge compensation flow path is fluidly connected to both vapor compression loops VC1, VC2. The pressure differential between the first connection point 102 and the third connection point 106 will cause working fluid to flow from the first vapor compression loop VC1 to the second vapor compression loop VC2.

[0098] In an embodiment, a position of the expansion valve 26c disposed between the second and third connections is adjustable to selectively control a flow of working fluid R therethrough. When the fluid conditioning system 20 transforms from a full load heating mode to a partial load heating mode, the cascade module 50 is fluidly decoupled from the indoor and outdoor units 30, 32. However, the working fluid R used by the two separate vapor compression cycles VC1, VC2 when operating under full load may exceed the working fluid R charge needed when operating under partial load. Accordingly, operation of the expansion valve 26c may be used to direct a portion of the working fluid R circulating within the single vapor compression loop to the accumulator 72 of the cascade module 50, and in some embodiments to the cascade compressor 52.

[0099] The controller C may be operably coupled to each of the first and second charge compensation valves CCV1, CCV2 as well as one or more of the expansion valves 26a, 26b, 26c. The at least one sensor S of the fluid conditioning system 20 may be a sensor operable to detect an amount of charge within each vapor compression loop VC1, VC2 and operate the charge compensation valves CCV1, CCV2 as needed to move working fluid between the vapor compression loops VC1, VC2 or to an accumulator 70, as necessary.

[0100] Inclusion of an active charge compensator 100 as described herein allows operation of a fluid conditioning system 20 configured as a cascaded heat pump without loss of performance as the system 20 transforms between different modes of operation.

[0101] With reference now to FIGS. 9A-11B, a fluid conditioning system 120 according to another embodiment is illustrated. It should be appreciated that the components of the fluid conditioning system 120 may be identical to the components of the fluid conditioning system 20 of FIGS. 3-8 and are numbered accordingly. As shown, the fluid conditioning system 120 includes an indoor unit 130 and an outdoor unit 132. A vapor compression system defined between the indoor and outdoor units 130, 132 includes a compressor 122, a first heat exchanger 124 arranged within the indoor unit 130, an expansion device 126a, such as an expansion valve for example, and a second heat exchanger 128 arranged at the outdoor unit 132. A four-way valve 142, such as a reversing valve for example, may be arranged along the flow path of the working fluid R of the fluid conditioning system 120 and in some embodiments, a receiver 170 may be located directly upstream from the compressor 122.

[0102] As in the previous embodiment, the fluid conditioning system 120 may include a cascade module 150 fluidly connectable to the vapor compression cycle to extend the operating conditions of the fluid conditioning system 120. The cascade module 150 may include a cascade compressor 152, a cascade heat exchanger 156, and in some embodiments, an expansion device 126c. Further, the cascade module 150 may additionally include one or more conduits operable to fluidly connect the components of the cascade module 150 to one another or to another portion of the fluid conditioning system 120. The cascade module 150 may further includes one or more conduits or flow control devices operable to directly fluidly connect the indoor and outdoor units 130, 132.

[0103] When the cascade module 150 is fluidly connected to the fluid conditioning system 120, the fluid conditioning system 120 is transformed from having a single vapor compression loop to having a plurality of fluidly separate vapor compression loops. For example, the fluid conditioning system 120 may include two fluidly separate compression loops, identified at VC1 and VC2 respectively, thermally coupled to one another. As in the previous embodiment of the fluid conditioning system 20 described herein, the fluid conditioning system 120 is transformable between a plurality of modes of operation. One or more cascade connection valves V1, V2 for example, are operable to selectively fluidly decouple or isolate one or more components of the cascade module 150, such as the cascade compressor 152 and the cascade heat exchanger 156 from the remainder of the fluid conditioning system 120. The cascade connection valves V1, V2 may be arranged within the housing containing the cascade module 150, but in some embodiments, may not be considered part of the cascade module 150.

[0104] A first cascade connection valve V1 is arranged along a flow path extending between the indoor unit 30 and the outdoor unit 32, such as between the four-way valve 42 and the first heat exchanger 24 for example. In embodiments where the fluid conditioning system 120 is operating in a partial load (heating or cooling) mode, the working fluid R bypasses the cascade heat exchanger 156 and is instead provided to the downstream indoor unit 130 via the first cascade connection valve V1. As shown, the first cascade connection valve V1 may be a reversing valve or a four-way valve and forms an interface between both the first and second vapor compression loops VC1, VC2. As illustrated in more detail in FIGS. 9B, 10B, and 11B, an exemplary four-way valve V1 includes a housing 200 having 4 ports formed therein through which working fluid R is provided to or output from the valve V1. A first port 202 arranged at a first side of the valve V1 is fluidly connected to and arranged downstream from an outlet of the four-way valve 142 when the fluid conditioning system 120 is operating in a heating mode. The second, third, and fourth ports 204, 206, 208 are arranged proximate an opposite side of the housing 200. The second port 204 may be fluidly connected to an inlet of the first heat exchanger 124 when the fluid conditioning system 120 is operating in a heating mode, the third port 206 may be fluidly connected to an outlet of the cascade compressor 152 when the fluid conditioning system 120 is operating in a heating mode and the fourth port 208 may be fluidly connected to an inlet of a first pass 162 of the cascade heat exchanger 156 when the fluid conditioning system 120 is operating in a heating mode.

[0105] Arranged within the hollow interior 210 of the housing 200 is a slider or shuttle mechanism 212 having four openings 214, 216, 218, 220 therein. The centrally located second and third openings 216, 218 are fluidly coupled to one another such that flow provided to one of the second port 204, third port 206, and fourth port 208, is redirected to another of the second port 204, third port 206, and fourth port 208. The shuttle mechanism 212 is movable between a first position (FIG. 9B, 10B) associated with flow of a working fluid R in a first direction and a second position (FIG. 11B) associated with the flow of the working fluid R in a second, opposite direction.

[0106] When in the first position, the first port 202 and the fourth port 208 are fluidly connected via opening 220 and the second port 204 and the third port 206 are fluidly connected via the openings 216 and 218. The shuttle mechanism 212 may block the first opening 214 to prevent any flow therethrough when in the first position. Similarly, when the shuttle mechanism 212 is in the second position, the first port 202 and the second port 204 are fluidly connected via the first opening 214 and the third port 206 and the fourth port 208 are fluidly connected via the second and third openings 216, 218. In the second position, the body of the shuttle mechanism 212 may block the fourth opening 220 to prevent any flow therethrough. The shuttle mechanism 212 is movable between the first and second positions based on the pressure differences acting thereon within the interior of housing. This pressure difference is controlled by a solenoid 222 fluidly connected to an interior of the housing 200 at both a first lateral side 224 of the shuttle mechanism 212, and a second lateral side 226 of the shuttle mechanism 212.

[0107] The fluid conditioning system 120 may include a second cascade connection valve V2, such as arranged along a fluid flow path extending between the indoor unit 30 and the outdoor unit 32, between the second heat exchanger 128 and the first heat exchanger 124 at a location proximate a fluid connection with the cascade heat exchanger 156. As described in the previous embodiment, in an embodiment, the second cascade connection valve V2 is a solenoid valve having an integral check valve feature. However, embodiments where the second cascade connection valve V2 includes a separate solenoid valve V2a and a bypass conduit extending including a check valve, as shown in FIGS. 4-6, are also contemplated herein.

[0108] When the cascade module 150 is fluidly connected to the fluid conditioning system 120, such as in a full load heating mode or a full load cooling mode, the first cascade connection valve V1 is in a first position. With reference to FIGS. 9A and 9B, during operation of the fluid conditioning system 120 in a full load heating mode, the cascade module 150 is fluidly connected to the fluid conditioning system 120. As shown, the four-way valve 142 is in a first position or state such that the working fluid R within the first vapor compression loop VC1 is configured to flow from the compressor 22 of the outdoor unit 32 to the cascade module.

[0109] The downstream four-way valve V1 may similarly be configured with the shuttle mechanism in a first position. In the first position, the first port and the fourth port are fluidly connected such that the flow of working fluid R provided to the first port is output to an inlet of the first pass 162 of the cascade heat exchanger 156. The first pass 162 of the cascade heat exchanger 156 functions as a condenser causing the working fluid R of the first vapor compression loop VC1 to be cooled therein. The cool liquid working fluid R output from the first pass 162 of the cascade heat exchanger 156 is provided to a downstream expansion device 126a and to the second heat exchanger 128 of the outdoor unit 132 operable as an evaporator, in series. The working fluid R output from the evaporator 128 is then returned to a suction inlet of the compressor 122 via the four-way valve 142 and the receiver 170, to repeat the cycle.

[0110] The working fluid R within the second vapor compressor loop VC2 is configured to flow from the outlet of the cascade compressor 52 of the cascade module 50 to the first heat exchanger 24. As noted above, during a full load heating mode, the shuttle mechanism of the downstream four-way valve V1 is in the first position. In the first position, the second port and the third port are fluidly connected to one another. Accordingly, the flow of working fluid R output from the cascade compressor 152 is provided to the third port and is redirected through the second port to the inlet of the first heat exchanger 124.

[0111] In the full load heating mode, the first heat exchanger 124 functions as a condenser, thereby cooling the working fluid R to a liquid. From the first heat exchanger 124, the working fluid R of the second vapor compression loop VC2 flows to an expansion device, such as the expansion device arranged within the indoor unit 130 or an expansion device 126c within the cascade module 150, and then to a second pass 164 of the cascade heat exchanger 156. The second pass 164 of the cascade heat exchanger 156 is operable as an evaporator such that heat from the working fluid R within the first pass 162 (from the first compression loop VC1) of the cascade heat exchanger 156 is transferred to the working fluid R within the second pass 164, thereby causing the working fluid R within the second pass 164 to at least partially vaporize. The at least partially vapor working fluid R output from the second pass 164 of the cascade heat exchanger 156 may then flow through a receiver 172, where excess or liquid working fluid R may be captured before being delivered to the cascade compressor 152 to repeat the cycle.

[0112] With reference to FIGS. 10A and 10B, the fluid conditioning system 120 during operation in a partial load heating mode, in which the cascade module 150 is not fluidly connected to the fluid conditioning system 120 is illustrated. To transform the fluid conditioning system from the full load heating mode to a partial load heating mode, the one or more cascade connection valves V1, V2 are operated to redirect the flow of working fluid away from the cascade module. For example, the second cascade connection valve is opened, allowing working fluid output from the outlet of the first heat exchanger 124 to flow directly to the expansion device 126a of the outdoor unit 132.

[0113] Similarly, the first cascade connection valve V1 is transformed by moving the shuttle mechanism from the first position to the second position, such as via operation of the solenoid operably coupled thereto. When the shuttle mechanism is in the second position, the first port is fluidly connected to the second port and the third port is fluidly connected to the fourth port. Connecting the first port and the second port allows the flow of working fluid output from the compressor 122 to be directed through the first cascade connection valve V1 directly to an inlet of the first heat exchanger 124. Because the cascade compressor 152 is not operational in the partial load heating mode, no fluid flow is provided to either the third port or the fourth port of the valve V1.

[0114] To transform the fluid conditioning system to a partial load cooling mode, the first cascade connection valve V1 and the second cascade connection valve V2 may remain in the same positions as in the partial load heating mode. More specifically, the shuttle mechanism of the first cascade connection valve V1 may remain in the second position, and the second cascade connection valve V2 may remain open. This maintains the direct fluid connection between the indoor unit 130 and the outdoor unit 132, thereby bypassing one or more components of the cascade module 150. However, in the partial load cooling mode, the four-way valve 142 is transformed from a first position associated with the heating modes of operation to a second position associated with the cooling modes of operation. With the four-way valve 142 in this second position, the flow output from the compressor 122 is provided via the four-way valve 142 to the second heat exchanger 128. The working fluid R is condensed within the second heat exchanger 128 and is then provided to the downstream expansion device 126a arranged within the outdoor unit 132. From the expansion device 126a, the working fluid R flows through the open second cascade connection valve V2 to the first heat exchanger 124, where the working fluid R is heated. The vapor working fluid R output from the first heat exchanger 124 is provided to the second port of the first cascade connection valve V1. Because the first portion and the second port are fluidly connected when the shuttle mechanism is in the second position, the flow from the first heat exchanger 124 delivered to the second port exits the valve V1 via the first port, and is provided to the compressor 122, via the first four-way valve 142 and the receiver 170.

[0115] The four-way valve 142 directly downstream from the compressor 122 is operable to control a direction of flow of the working fluid R through the fluid conditioning system 120. The four-way valve or reversing valve operable as the first cascade connection valve V1, is therefore operable to control when the working fluid is provided to the cascade module, and when the working fluid bypasses the cascade module.

[0116] With reference now to FIG. 12, a fluid conditioning system 320 according to another embodiment is illustrated. Components of the fluid conditioning system 320 that are comparable to the components of the fluid conditioning system 20 of FIGS. 3-8 and are similarly numbered. As shown, the fluid conditioning system 320 includes an indoor unit 330 and an outdoor unit 332. A vapor compression system defined between the indoor and outdoor units 330, 332 includes a compressor 322, a first heat exchanger 324 arranged within the indoor unit 330, an expansion device 326a, such as an expansion valve for example, and a second heat exchanger 328 arranged at the outdoor unit 332. A four-way valve 342 may be arranged along the flow path of the working fluid R of the fluid conditioning system 320 and in some embodiments, an accumulator 370 may be located directly upstream from the compressor 322.

[0117] As in a previous embodiment, the fluid conditioning system 320 may include a cascade module 350 fluidly connectable to the vapor compression cycle to extend the operating conditions of the fluid conditioning system 320. The cascade module 350 may include a cascade compressor 352, a cascade heat exchanger 356, and in some embodiments, a cascade expansion device 326c. Further, the cascade module 350 may additionally include one or more conduits operable to fluidly connect the components of the cascade module 350 to one another or to another portion of the fluid conditioning system 320. The cascade module 350 may further includes one or more conduits or flow control devices operable to directly fluidly connect the indoor and outdoor units 330, 332.

[0118] When the cascade module 350 is fluidly connected to the fluid conditioning system 320, the fluid conditioning system 320 is transformed from having a single vapor compression loop to having a plurality of fluidly separate vapor compression loops. For example, the fluid conditioning system 320 may include two fluidly separate compression loops, identified at VC1 and VC2 respectively, thermally coupled to one another. As in the previous embodiment of the fluid conditioning system 20 described herein, the fluid conditioning system 320 is transformable between a plurality of modes of operation. One or more cascade connection valves V1, V2 for example, are operable to selectively fluidly decouple or isolate one or more components of the cascade module 350, such as the cascade compressor 352 and the cascade heat exchanger 356 from the remainder of the fluid conditioning system 320. The cascade connection valves V1, V2 may be arranged within the housing containing the cascade module 350, but in some embodiments, may not be considered part of the cascade module 350.

[0119] A first cascade connection valve V1 is arranged along a flow path extending between the indoor unit 330 and the outdoor unit 332, such as between the reversing valve 342 and the first heat exchanger 324 for example. In embodiments where the fluid conditioning system 320 is operating in a partial load (heating or cooling) mode, the working fluid R bypasses the cascade heat exchanger 356 and is instead provided to the downstream indoor unit 330 via the first cascade connection valve V1. As shown, the first cascade connection valve V1 may be a reversing valve or a four way valve and forms an interface between both the first and second vapor compression loops VC1, VC2.

[0120] In the illustrated, non-limiting embodiment, the fluid conditioning system 320 additionally includes a secondary outdoor unit module 400 selectively fluidly connectable to the remainder of the fluid conditioning system. The secondary outdoor unit module 400 may be an integral portion of the fluid conditioning system 320, or alternatively, may be a separate module that can be attached to and removed from both new and existing fluid conditioning systems. When installed, the secondary outdoor unit module 400 may be fluidly coupled to at least a portion of the fluid conditioning system 320, such as to the outdoor unit 332 and/or to the cascade module 350.

[0121] As shown, the secondary outdoor unit module 400 includes a second outdoor compressor 380, a second outdoor heat exchanger 382, a second outdoor expansion device 384, and in some embodiments, a second outdoor receiver or accumulator 386 and/or a second outdoor four-way valve 388. It should be appreciated that the secondary outdoor unit module 400 may additionally include one or more conduits operable to fluidly connect the components of the secondary outdoor unit module 400 to one another or to another portion of the fluid conditioning system. The component of the secondary outdoor unit module 400, such as the second outdoor compressor 380, a second outdoor heat exchanger 382, a second outdoor expansion device 384, and second outdoor accumulator 386 for example, may be packaged within a single housing or unit. This housing (not shown) may be separate from the housing 360 of the cascade module 350. However, in other embodiments, the secondary outdoor unit module 400 is located within the housing 360 of the cascade module 350. In such embodiments, the secondary outdoor unit module 400 may but need not be considered part of the cascade module 350.

[0122] The secondary outdoor unit module 400 is fluidly connectable to the fluid conditioning system 320 during one or more modes of operation. The secondary outdoor unit module 400 may be considered to be fluidly connected to the fluid conditioning system 320 in embodiments where the working fluid R is provided to at least one of the components (i.e., a second outdoor compressor 380, a second outdoor heat exchanger 382, a second outdoor expansion device 384, the second outdoor reversing valve 388) of the secondary outdoor unit module 400. In an embodiment, the secondary outdoor unit module 400 is only suitable for use with the fluid conditioning system 320 when the cascade module 350 is also fluidly connected thereto. The secondary outdoor unit module 400 may include one or more valves operable to control the delivery of working fluid R to the cascade module 350, and the receipt of working fluid R from the cascade module 350. In such embodiments, the secondary outdoor unit module 400 may not be fluidly connected to the fluid conditioning system 320 even when the cascade module 350 is fluidly connected to the fluid conditioning system 320.

[0123] As previously noted, when the cascade module 350 is fluidly connected to the fluid conditioning system 320, the compressor, cascade heat exchanger 356, expansion device 326a, and second heat exchanger 328 form a first vapor compression loop VC1, and the cascade compressor 352, first heat exchanger 324, cascade expansion device 326c, and cascade heat exchanger 356 form a second vapor compression loop VC2. When the secondary outdoor unit module 400 is fluidly connected to the fluid conditioning system 320, the secondary outdoor unit module 400 may be connected to or form part of the first vapor compression loop VC1. In an embodiment, the outdoor unit 332 and the secondary outdoor unit module 400 are fluidly connected to the cascade heat exchanger 356 in parallel.

[0124] As shown, the second outdoor expansion device 384 may be fluidly coupled to the first pass 362 of the cascade heat exchanger 356 in parallel with the expansion device 326a of the outdoor unit 332. Accordingly, during operation in a heating mode, a first portion R1 of the working fluid output from the first pass 362 of the cascade heat exchanger 356 is provided to the expansion device 326a, the second heat exchanger 328, the reversing valve 242 and the compressor 322 in series, and a second portion R2 of the working fluid output from the first pass 362 of the cascade heat exchanger 356 is provided to the second outdoor expansion device 384, the second outdoor heat exchanger 382, the second outdoor reversing valve 388 and the second outdoor compressor 380 in series. This division of the working fluid R of the first vapor compression loop VC1 into a first portion R1 and a second portion R2 may, but need not occur downstream from the check valve CV3. The first portion R1 of the working fluid output from the compressor 322 may be mixed with the second portion R2 of the working fluid output from the second outdoor compressor 380, downstream of the reversing valve 342 and the second outdoor reversing valve 388, respectively. In an embodiment, this mixing occurs upstream from an inlet of the first pass 362 the cascade heat exchanger 356.

[0125] As shown, the reversing valves 342, 388 are in a first position or state such that the working fluid R within the first vapor compression loop VC1 is configured to flow in a first direction. However, in embodiments where the reversing valves 342, 388 are transformed to the second position, causing the working fluid R to flow in a second, opposite direction, the outdoor unit 332 and the secondary outdoor unit module 400 will similarly be arranged in parallel relative to the flow of the working fluid.

[0126] During operation in a cooling mode, the cascade heat exchanger 356 is operable as an evaporator. A first portion R1 of the hot working fluid output from the first pass 362 of the cascade heat exchanger 356 is provided to the reversing valve 342, the compressor 322, the second heat exchanger 328, and the expansion device 326a in series, and a second portion R2 of the working fluid output from the first pass 362 of the cascade heat exchanger 356 is provided to the second outdoor reversing valve 388, the second outdoor compressor 380, the second outdoor heat exchanger 382, and the second outdoor expansion device 384 in series. The first portion R1 of the working fluid output from the expansion device 326a may be mixed with the second portion R2 of the working fluid output from the second outdoor expansion device 384 at a location upstream from an inlet of the first pass 362 the cascade heat exchanger 356.

[0127] With reference now to FIG. 13, yet another embodiment of a fluid conditioning system 320 including a cascade module 350 and a secondary outdoor unit module 400 fluidly connectable to the indoor unit 330 and outdoor unit 332 of a fluid conditioning system 320 is illustrated. However, unlike the previous embodiment shown in FIG. 12, the secondary outdoor unit module 400 does not form a portion of the first vapor compression loop VC1. On the contrary, in the illustrated, non-limiting embodiment, when the secondary outdoor unit module 400 is connected to the fluid conditioning system 320, the fluid conditioning system 320 includes three fluidly separate vapor compression loops VC1, VC2, VC3. As shown, the secondary outdoor unit module 400 may form its own vapor compression loop VC3 thermally coupled to at least one of the other vapor compression loops, such as the second vapor compression loop VC2 for example.

[0128] The secondary outdoor unit module 400 of FIG. 13 may be substantially identical to the secondary outdoor unit module 400 illustrated and described with respect to FIG. 12. However, in the embodiment of FIG. 13, the secondary outdoor unit module 400 additionally includes a second outdoor interface heat exchanger 390. The second outdoor interface heat exchanger 390 is fluidly connectable to another of the vapor compression loops of the fluid conditioning system.

[0129] During operation in a heating mode with the secondary outdoor unit module 400 connected, as shown, the reversing valve 342 is in a first position such that the working fluid R within the first vapor compression loop VC1 is configured to flow from the compressor 322 of the outdoor unit 332 to a first pass 362 of the cascade heat exchanger 356 of the cascade module 350. The first pass 362 of the cascade heat exchanger 356 functions as a condenser causing the working fluid R of the first vapor compression loop VC1 to be cooled therein. The cool liquid working fluid R output from the first pass 362 of the cascade heat exchanger 356 may be provided to the expansion device 326a and to the second heat exchanger 328 of the outdoor unit 332 operable as an evaporator, in series. The vapor working fluid R output from the evaporator 328 is then returned to a suction inlet of the compressor 322 via the reversing valve 342 to repeat the cycle.

[0130] The working fluid R within the second vapor compressor loop VC2 is configured to flow from the outlet of the cascade compressor 352 of the cascade module 350 to the first heat exchanger 324. The first heat exchanger 324 is operable as a condenser, thereby cooling the working fluid R to a liquid. From the first heat exchanger 324, the working fluid R of the second vapor compression loop VC2 flows to an expansion device, such as the expansion device 326c within the cascade module 350, and then to a second pass 364 of the cascade heat exchanger 356. The second pass 364 of the cascade heat exchanger 356 is operable as an evaporator such that heat from the working fluid R within the first pass 362 (from the first compression loop VC1) of the cascade heat exchanger 356 is transferred to the working fluid R within the second pass 364, thereby causing the working fluid R within the second pass 364 to at least partially vaporize.

[0131] In the illustrated, non-limiting embodiment, the second pass of the cascade heat exchanger 356 is fluidly connected to a first pass 392 of the second outdoor interface heat exchanger 390. The first pass 392 of the second outdoor interface heat exchanger 390 is also configured as an evaporator such that heat from the working fluid R within a second pass 394 (from the third compression loop VC3 to be described in more detail below) of the second outdoor interface heat exchanger 390 is transferred to the working fluid R within the first pass 392. From the second outdoor interface heat exchanger 390, the working fluid R is returned to the inlet of the cascade compressor 352 of the cascade module 350 to repeat the cycle.

[0132] The second outdoor reversing valve 388 may also be in a first position such that the working fluid R within the third vapor compression loop VC3 is configured to flow from the second outdoor compressor 380 to a first pass 362 of the, through the second outdoor reversing valve 388, to the second pass 394 of the second outdoor interface heat exchanger 390. The second pass 394 of the second outdoor interface heat exchanger 390 functions as a condenser causing the working fluid R of the third vapor compression loop VC3 to be cooled therein. The cool liquid working fluid R output from the second pass 394 of the second outdoor interface heat exchanger 390 may be provided to the second outdoor expansion device 384 and to the second outdoor heat exchanger 382, in series. The second outdoor heat exchanger 382 is operable as an evaporator, such that the working fluid R is heated therein. The at least partially vapor working fluid R output from the second outdoor heat exchanger 382 is then returned to a suction inlet of the second outdoor compressor 380 via the second outdoor reversing valve 388 to repeat the cycle. In the non-limiting configuration illustrated, the working fluid R of the second vapor compression loop VC2 is thermally coupled to the first vapor compression loop VC1 and the third vapor compression loop VC3 in series.

[0133] In embodiments where the secondary outdoor unit module 400 is not operational, the second outdoor interface heat exchanger 390 of the secondary outdoor unit module 400 may but need not remain fluidly connected to the cascade heat exchanger 356. If the working fluid of the second vapor compression loop VC2 passes through the second outdoor interface heat exchanger 390 when the secondary outdoor unit module 400 is not operational no conditioning of the working fluid will occur therein. It should be understood that the in embodiments where the second vapor compression loop VC2 additionally includes a reversing valve, the fluid conditioning system including the cascade module 350 and the secondary outdoor unit module 400 may also be operable in a cooling mode.

[0134] The addition of a secondary outdoor unit module 400 into the fluid conditioning system 320 increases the availability of heat during operating conditions for which a regular heat pump cannot supply the required capacity. It enables higher capacities even when compared to a fluid conditioning system having a cascade module that does not have an additional low temperature heat source.

[0135] With reference now to FIG. 14, a fluid conditioning system 520 according to another embodiment is illustrated. Components of the fluid conditioning system 520 that are comparable to the components of the fluid conditioning system 20 of FIGS. 3-8 and are similarly numbered. As shown, the fluid conditioning system 520 includes an indoor unit 530 and an outdoor unit 532. A vapor compression system defined between the indoor and outdoor units 530, 532 includes a compressor 522, a first heat exchanger 524 arranged within the indoor unit 530, an expansion device 526a, such as an expansion valve for example, and a second heat exchanger 528 arranged at the outdoor unit 532. A four-way valve, such as a reversing valve 542 may be arranged along the flow path of the working fluid R of the fluid conditioning system 520 and in some embodiments, a receiver or accumulator 570 may be located directly upstream from the compressor 522.

[0136] As in the previous embodiment, the fluid conditioning system 520 may include a cascade module 550 fluidly connectable to the vapor compression cycle to extend the operating conditions of the fluid conditioning system 520. The cascade module 550 may include a cascade compressor 552, a cascade heat exchanger 556, and in some embodiments, a cascade expansion device 526c. Further, the cascade module 550 may additionally include one or more conduits operable to fluidly connect the components of the cascade module 550 to one another or to another portion of the fluid conditioning system 520. The cascade module 550 may further includes one or more conduits or flow control devices operable to directly fluidly connect the indoor and outdoor units 530, 532.

[0137] When the cascade module 550 is fluidly connected to the fluid conditioning system 520, the fluid conditioning system 520 is transformed from having a single vapor compression loop to having a plurality of fluidly separate vapor compression loops. For example, the fluid conditioning system 520 may include two fluidly separate compression loops, identified at VC1 and VC2 respectively, thermally coupled to one another. As in the previous embodiment of the fluid conditioning system 20 described herein, the fluid conditioning system 520 is transformable between a plurality of modes of operation. One or more cascade connection valves V1, V2 for example, are operable to selectively fluidly decouple or isolate one or more components of the cascade module 550, such as the cascade compressor 552 and the cascade heat exchanger 556 from the remainder of the fluid conditioning system 520. The cascade connection valves V1, V2 may be arranged within the housing containing the cascade module 550, but in some embodiments, may not be considered part of the cascade module 550.

[0138] A first cascade connection valve V1 is arranged along a flow path extending between the indoor unit 530 and the outdoor unit 532, such as between the reversing valve 542 and the first heat exchanger 524 for example. In embodiments where the fluid conditioning system 520 is operating in a partial load (heating or cooling) mode, the working fluid R bypasses the cascade heat exchanger 556 and is instead provided to the downstream indoor unit 530 via the first cascade connection valve V1. As shown, the first cascade connection valve V1 may be a reversing valve or a four way valve and forms an interface between both the first and second vapor compression loops VC1, VC2.

[0139] In an embodiment, the cascade module 550 is fluidly and thermally coupled to a second heat source. In the illustrated, non-limiting embodiment, the second heat source associated with the cascade module 550 is a geothermal loop 600 having a geothermal heat exchanger 602 fluidly couplable to the second vapor compression loop of the fluid conditioning system 520. The geothermal heat exchanger 602 may be any suitable type of heat exchanger operable to transfer heat between the working fluid R and a second medium F, such as water of a geothermal loop for example. The geothermal loop 600 may include a pump 604 operable to urge or otherwise move the second medium F through the geothermal heat exchanger 602. In an embodiment, the second medium F of the geothermal loop 600 may be at a temperature greater than the temperature of the ambient air surrounding the outdoor unit 532 and heat from the second medium F is transferrable to the working fluid R of the second vapor compression loop VC2.

[0140] As shown, the geothermal heat exchanger 602 may be positioned downstream from the second pass 564 of the cascade heat exchanger 556 with respect to the flow of working fluid R in the second vapor compression loop VC2. In some embodiments, the geothermal heat exchanger 602 is located downstream from the four-way valve 554 of the cascade module 550 relative to the flow of working fluid R in the second vapor compression loop VC2. Alternatively, or in addition, the geothermal heat exchanger 602 may be positioned upstream from an inlet of the cascade compressor 552 of the cascade module 550 relative to the flow of working fluid R in the second vapor compression loop VC2. In an embodiment, the geothermal heat exchanger 602 is arranged directly upstream from the inlet of the cascade compressor 552. However, embodiments where the geothermal heat exchanger 602 is arranged directly upstream from the cascade accumulator 572 or directly downstream or upstream from the reversing valve 554 are also contemplated herein. It should be appreciated that the geothermal heat exchanger 602 may form part of the cascade module 150 and/or may be arranged within the housing 560 of the cascade module 550. However, embodiments where the geothermal heat exchanger is located remotely from the cascade module are also contemplated herein.

[0141] With continued reference to FIG. 14, during operation of the fluid conditioning system 520 in a full load heating mode, the cascade module 550 is fluidly connected to the fluid conditioning system 520. The reversing valve 542 is in a first position or state such that the working fluid R within the first vapor compression loop VC1 is configured to flow from the compressor 522 of the outdoor unit 532 to the first pass 562 of the cascade heat exchanger 556 of the cascade module 550. The first pass 562 of the cascade heat exchanger 556 functions as a condenser causing the working fluid R of the first vapor compression loop VC1 to be cooled therein. The cool liquid working fluid R output from the first pass 562 of the cascade heat exchanger 556 may be provided to the expansion device 526 and to the second heat exchanger 528 of the outdoor unit 532 operable as an evaporator, in series. The vapor working fluid R output from the evaporator 528 is provided to the reversing valve 542 and is directed to pass through the accumulator 570 to the inlet of the compressor 522 to repeat the cycle. In an embodiment, the flow path of the working fluid R within the first vapor compression loop VC1 is the same when the cascade module 550 is fluidly coupled to a geothermal loop 600 and when the cascade module 550 is not coupled to a geothermal loop.

[0142] The working fluid R within the second vapor compressor loop VC2 is configured to flow from the outlet of the cascade compressor 552 of the cascade module 550 to the first heat exchanger 524. In the full load heating mode, the first heat exchanger 524 functions as a condenser, thereby cooling the working fluid R to a liquid. From the first heat exchanger 524, the working fluid R of the second vapor compression loop VC2 flows to an expansion device, such as the expansion device arranged within the indoor unit 530 or an expansion device 526c within the cascade module 550, and then to a second pass 564 of the cascade heat exchanger 556. The second pass 564 of the cascade heat exchanger 556 is operable as an evaporator such that heat from the working fluid R within the first pass 562 (from the first compression loop VC1) of the cascade heat exchanger 556 is transferred to the working fluid R within the second pass 564, thereby causing the working fluid R within the second pass 564 to at least partially vaporize. The working fluid R output from the second pass 564 has a higher vapor quality and enthalpy than the working fluid R provided to the second pass 564. In the illustrated, non-limiting embodiment, the working fluid R output from the second pass 564 of the cascade heat exchanger is provided to the cascade reversing valve 554.

[0143] The working fluid R output from the reversing valve 554 is then configured to flow through the geothermal heat exchanger 602, where the working fluid R is further heated by the second heat source. Heat from the hot second medium F provided to the geothermal heat exchanger 602 is transferred to the working fluid R within the geothermal heat exchanger 602 to further vaporize the liquid working fluid R. The resulting vapor working fluid R output from the geothermal heat exchanger 602 may then be provided to the cascade accumulator 572 and to the inlet of the cascade compressor 552 to repeat the cycle. Although the working fluid R within the second vapor compression loop VC2 is illustrated and described herein as being fluidly coupled to a geothermal loop and heated by the second medium F therein, it should be appreciated that any suitable heat source may be thermally coupled to second vapor compression loop VC2 at the described location to further heat the working fluid R upstream from the cascade compressor 552. Further, because the second heat source is fluidly coupled to the cascade module, the second heat source is isolated from the single vapor compression loop of the fluid conditioning system when the cascade module 550 is not fluidly connected to the indoor and outdoor units 530, 532 of the heat pump.

[0144] A cascade module 550 thermally and fluidly connected to another heat source may be used to achieve a higher capacity of the fluid conditioning system. The heat source is positioned to increase the evaporating capacity of the high pressure or second vapor compression loop. This higher temperature allows for a significant increase in the flow rate of the working fluid and the heating capacity that can be achieve at the indoor unit 530.

[0145] According to an embodiment, an assembly includes a fluid conditioning system including a four-way valve operable to control a direction of flow of a working fluid within the fluid conditioning system between a first direction and a second direction, and a cascade module. A plurality of valves are operably coupled to the fluid conditioning system and the cascade module. The plurality of valves are operable to fluidly couple the cascade module to the fluid conditioning system during a first mode of operation, and the plurality of valves are operable to bypass the cascade module during a second mode of operation. At least one of the plurality of valves is another four-way valve.

[0146] In addition to one or more of the features described herein, or as an alternative, in further embodiments the fluid conditioning system is a heat pump including an indoor unit and an outdoor unit. The cascade module is fluidly connectable to the fluid conditioning system between the indoor unit and the outdoor unit.

[0147] In addition to one or more of the features described herein, or as an alternative, in further embodiments the fluid conditioning system includes a compressor, a first heat exchanger, at least one expansion valve, and a second heat exchanger and the plurality of valves operable to fluidly couple the cascade module to the fluid conditioning system includes a first cascade connection valve and a second cascade connection valve. The first cascade connection valve is fluidly connected to the fluid conditioning system between the compressor and the first heat exchanger when the working fluid is flowing in the first direction. The second cascade connection valve is fluidly connected to the fluid conditioning system between the first heat exchanger and the expansion valve when the working fluid is flowing in the first direction.

[0148] In addition to one or more of the features described herein, or as an alternative, in further embodiments at least one of the first cascade connection valve and the second cascade connection valve is a solenoid valve having an integral check valve feature.

[0149] In addition to one or more of the features described herein, or as an alternative, in further embodiments at least one of the first cascade connection valve and the second cascade connection valve includes a solenoid valve, a bypass conduit arranged in parallel with the solenoid valve, and a check valve arranged at the bypass conduit.

[0150] In addition to one or more of the features described herein, or as an alternative, in further embodiments during the second mode of operation, the check valve is oriented such that the working fluid is configured to flow through the check valve in the first direction, and the working fluid is configured to flow through the solenoid valve in the second direction.

[0151] In addition to one or more of the features described herein, or as an alternative, in further embodiments the another four-way valve is in a first position during the first mode of operation and the another four-way valve is in a second position during the second mode of operation.

[0152] In addition to one or more of the features described herein, or as an alternative, in further embodiments the fluid conditioning system includes a vapor compression system arranged within an outdoor unit and an indoor unit, wherein the outdoor unit and the indoor unit are fluidly separate when another four-way valve is in the first position.

[0153] In addition to one or more of the features described herein, or as an alternative, in further embodiments the another four-way valve forms an interface between a first vapor compression loop associated with the outdoor unit and a second vapor compression loop associated with the indoor unit during the first mode of operation.

[0154] In addition to one or more of the features described herein, or as an alternative, in further embodiments the outdoor unit is directly fluidly connected to the indoor unit when the another four-way valve is in the second position.

[0155] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module includes a cascade compressor and a cascade heat exchanger. The another four-way valve is directly fluidly connected to an outlet of the cascade compressor and directly fluidly connected to the cascade heat exchanger.

[0156] In addition to one or more of the features described herein, or as an alternative, in further embodiments the another four-way valve is directly fluidly connected to the four-way valve.

[0157] In addition to one or more of the features described herein, or as an alternative, in further embodiments the fluid conditioning system includes a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger, and the another four-way valve is directly fluidly connected to the first heat exchanger.

[0158] In addition to one or more of the features described herein, or as an alternative, in further embodiments the plurality of valves further includes an expansion valve arranged within the cascade module.

[0159] In addition to one or more of the features described herein, or as an alternative, in further embodiments a controller is operably coupled to the fluid conditioning system, the cascade module, and the plurality of valves. The controller is configured to determine an identified mode of operation associated with a demand on the fluid conditioning system and operate at least one of the plurality of valves to initiate operation of the fluid conditioning system in the identified mode.

[0160] In addition to one or more of the features described herein, or as an alternative, in further embodiments at least one sensor is operably coupled to the controller. The at least one sensor is configured to monitor at least one parameter or operating condition associated with the fluid conditioning system.

[0161] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module is packaged within a housing, and the plurality of valves operably coupled to the cascade module are also packaged within the housing.

[0162] According to an embodiment, an assembly includes a fluid conditioning system configured as a heat pump having an indoor unit and an outdoor unit, and a cascade module fluidly connectable to the fluid conditioning system to increase a capacity of the fluid conditioning system. A secondary outdoor unit module is fluidly connectable to the fluid conditioning system to further increase the capacity of the fluid conditioning system.

[0163] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module and the secondary outdoor unit module are separately connectable to the fluid conditioning system.

[0164] In addition to one or more of the features described herein, or as an alternative, in further embodiments the secondary outdoor unit module is only fluidly connected to the fluid conditioning system when the cascade module is fluidly connected to the fluid conditioning system.

[0165] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module is arranged within a first housing and the secondary outdoor unit module is arranged within a separate housing.

[0166] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module and the secondary outdoor unit module are packaged within a single housing.

[0167] In addition to one or more of the features described herein, or as an alternative, in further embodiments the fluid conditioning system includes a compressor, a first heat exchanger, at least one expansion device, and a second heat exchanger and the cascade module includes a cascade compressor and a cascade heat exchanger.

[0168] In addition to one or more of the features described herein, or as an alternative, in further embodiments the secondary outdoor unit module further includes a second outdoor compressor, a second outdoor heat exchanger, and a second outdoor expansion device.

[0169] In addition to one or more of the features described herein, or as an alternative, in further embodiments the secondary outdoor unit module further includes a second outdoor interface heat exchanger arranged in series with the cascade heat exchanger relative to a flow of working fluid.

[0170] In addition to one or more of the features described herein, or as an alternative, in further embodiments a plurality of valves are operably coupled to the fluid conditioning system and the cascade module. The plurality of valves are operable to fluidly couple the cascade module to the fluid conditioning system during a first mode of operation and the plurality of valves are operable to bypass the cascade module during a second mode of operation.

[0171] In addition to one or more of the features described herein, or as an alternative, in further embodiments a controller is operably coupled to the compressor, the cascade compressor, the second outdoor compressor, and the plurality of valves. The controller is configured to identify a mode of operation associated with a demand on the fluid conditioning system and operate the at plurality of valves to initiate operation in the identified mode.

[0172] In addition to one or more of the features described herein, or as an alternative, in further embodiments at least one sensor is operably coupled to the controller. The at least one sensor is configured to monitor at least one parameter or operating condition associated with the fluid conditioning system.

[0173] In addition to one or more of the features described herein, or as an alternative, in further embodiments when the cascade module is fluidly connected to the fluid conditioning system during a first mode of operation, the assembly includes a first vapor compression loop and a second vapor compression loop. The first vapor compression loop and the second vapor compression loop are thermally coupled at the cascade module.

[0174] In addition to one or more of the features described herein, or as an alternative, in further embodiments when the secondary outdoor unit module is fluidly connected to the fluid conditioning system during a first mode of operation, the outdoor unit and the secondary outdoor unit module are arranged in parallel relative to the cascade module within the first vapor compression loop.

[0175] In addition to one or more of the features described herein, or as an alternative, in further embodiments when the secondary outdoor unit module is fluidly connected to the fluid conditioning system during a first mode of operation, the assembly includes the first vapor compression loop, the second vapor compression loop, and a third vapor compression loop.

[0176] In addition to one or more of the features described herein, or as an alternative, in further embodiments the first vapor compression loop and the second vapor compression loop are thermally coupled at the cascade module, and the second vapor compression loop and the third vapor compression loop are thermally coupled at the secondary outdoor unit module.

[0177] According to an embodiment, a method of operating a fluid conditioning system includes receiving a demand on the fluid conditioning system and determining a mode of operation in response to the demand by comparing the demand with a heating capacity of the fluid conditioning system. Fluidly connecting only a cascade module to the fluid conditioning system in response to the demand being greater than the heating capacity of the fluid conditioning system, and fluidly connecting both the cascade module and a secondary outdoor unit module to the fluid conditioning system in response to the demand being greater than the heating capacity of the fluid conditioning system.

[0178] In addition to one or more of the features described herein, or as an alternative, in further embodiments fluidly connecting the cascade module to the fluid conditioning system includes operating at least one valve to control a flow of refrigerant to the cascade module.

[0179] In addition to one or more of the features described herein, or as an alternative, in further embodiments fluidly isolating the cascade module and the secondary outdoor unit module from the fluid conditioning system in response to the demand being less than the heating capacity of the fluid conditioning system.

[0180] According to an embodiment, a fluid conditioning system includes a heat pump having an indoor unit and an outdoor unit and a cascade module fluidly connectable to the heat pump to increase a capacity of the heat pump. A first heat source is associated with the heat pump and a second heat source is associated with the cascade module. During a first mode, the cascade module is fluidly connected to the heat pump and the fluid conditioning system has a first vapor compression loop thermally coupled to a second vapor compression loop. During a second mode, the cascade module is fluidly isolated from the heat pump and the fluid conditioning system has a single vapor compression loop. The second heat source is operable to heat a working fluid circulating within the second vapor compression loop during the second mode.

[0181] In addition to one or more of the features described herein, or as an alternative, in further embodiments in the first mode, the first heat source is operable to heat the working fluid circulating through the single vapor compression loop, and in the second mode, the first heat source is operable to heat the working fluid circulating in one of the first vapor compression loop and the second vapor compression loop.

[0182] In addition to one or more of the features described herein, or as an alternative, in further embodiments the first heat source is outside air.

[0183] In addition to one or more of the features described herein, or as an alternative, in further embodiments the second heat source is a second medium circulating within a geothermal loop.

[0184] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module is thermally coupled to the second heat source via a geothermal heat exchanger.

[0185] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module includes a cascade compressor and a cascade heat exchanger. The geothermal heat exchanger is arranged downstream from the cascade heat exchanger relative to a flow of working fluid through the cascade module.

[0186] In addition to one or more of the features described herein, or as an alternative, in further embodiments the geothermal heat exchanger is arranged directly upstream from an inlet of the cascade compressor relative to the flow of working fluid through the cascade module.

[0187] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module includes a four-way valve positioned downstream from the cascade heat exchanger and upstream from the cascade compressor relative to the flow of working fluid through the cascade module. The geothermal heat exchanger is positioned directly downstream from the four-way valve.

[0188] In addition to one or more of the features described herein, or as an alternative, in further embodiments the cascade module includes an accumulator positioned directly upstream from an inlet of the cascade compressor relative to the flow of working fluid. The geothermal heat exchanger is arranged directly upstream from the accumulator.

[0189] In addition to one or more of the features described herein, or as an alternative, in further embodiments the geothermal heat exchanger is arranged within a housing of the cascade module.

[0190] In addition to one or more of the features described herein, or as an alternative, in further embodiments a temperature of the second heat source is greater than a temperature of the first heat source.

[0191] In addition to one or more of the features described herein, or as an alternative, in further embodiments during the first mode, the first vapor compression loop and the second vapor compression loop are thermally coupled at the cascade module.

[0192] In addition to one or more of the features described herein, or as an alternative, in further embodiments a plurality of valves are operably coupled to the heat pump and the cascade module and are operable to transform the fluid conditioning system between the first mode and the second mode.

[0193] In addition to one or more of the features described herein, or as an alternative, in further embodiments a controller is operably coupled to the plurality of valves. The controller is configured to operate the plurality of valves to transform the fluid conditioning system between the first mode and the second mode in response to a demand of the fluid conditioning system.

[0194] According to an embodiment, a method of operating a fluid conditioning system includes fluidly connecting a heat pump to a cascade module to form a separate first vapor compression loop and a second vapor compression loop, heating a working fluid of the second vapor compression loop via a first heat source, further heating the working fluid of the second vapor compression loop via a second heat source and compressing the working fluid heated via the second heat source at a cascade compressor. The first heat source is the first vapor compression loop.

[0195] In addition to one or more of the features described herein, or as an alternative, in further embodiments further heating the working fluid of the second vapor compression loop increases an evaporating capacity of the second vapor compression loop.

[0196] In addition to one or more of the features described herein, or as an alternative, in further embodiments further heating the working fluid of the second vapor compression loop includes passing the working fluid through a geothermal heat exchanger configured to receive a second medium of a geothermal loop.

[0197] In addition to one or more of the features described herein, or as an alternative, in further embodiments heating the working fluid via the first heat source occurs at a cascade heat exchanger fluidly connecting the first vapor compression loop and the second vapor compression loop. The further heating the working fluid of the second vapor compression loop occurs downstream from the cascade heat exchanger and upstream from the cascade compressor.

[0198] In addition to one or more of the features described herein, or as an alternative, in further embodiments accumulating liquid working fluid within the second vapor compression loop at an accumulator located upstream from the cascade compressor. The further heating the working fluid of the second vapor compression loop occurs upstream from the accumulator.

[0199] In addition to one or more of the features described herein, or as an alternative, in further embodiments operating at least one valve to fluidly disconnect the cascade module from the heat pump. The second heat source isolated from the heat pump when the cascade module is fluidly disconnected from the heat pump.

[0200] The term about is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application.

[0201] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present 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 the terms comprises and/or comprising, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

[0202] While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.