MULTI-CIRCUIT CLIMATE CONTROL SYSTEMS

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

BACKGROUND

A climate control system may circulate a refrigerant through a plurality of heat exchangers to transfer heat between an interior space and an ambient environment. The interior space may be an interior space of a house, apartment, building, retail store, storage unit, office, refrigerator, freezer, vehicle, etc. The ambient environment may be an outdoor environment that at least partially surrounds the interior space.

Some refrigerants that have been used in climate control systems have been found to have adverse effects on the environment. Thus, there has been a desire to utilize alternative refrigerants in climate control systems that may have a reduced negative impact on the environment, having a lower so-called global warming potential (GWP).

BRIEF SUMMARY

Some embodiments disclosed herein are directed to a heat pump for conditioning an interior space. In some embodiments, the heat pump includes a thermal fluid circuit that is configured to circulate a thermal fluid. In addition, the heat pump includes an outdoor unit including a refrigerant circuit that is configured to circulate a refrigerant to cool the thermal fluid during a cooling mode of the heat pump and to heat the thermal fluid during a heating mode of the heat pump. The outdoor unit also includes a first heat exchanger positioned along the refrigerant circuit that is configured to exchange heat between the refrigerant and the thermal fluid and a second heat exchanger positioned along the refrigerant circuit that is configured to exchange heat between the refrigerant of the refrigerant circuit and an outdoor environment surrounding the outdoor unit. A refrigerant volume of the second heat exchanger is larger than a refrigerant volume of the first heat exchanger. The outdoor unit also includes a charge compensator positioned along the refrigerant circuit that is configured to receive excess refrigerant therein when the heat pump operates in the heating mode and configured to discharge the excess refrigerant to the refrigerant circuit when the heat pump operates in the cooling mode. Further, the heat pump includes an air handler having a third heat exchanger that is configured to exchange heat between the thermal fluid circuit and an airflow for the interior space.

Some embodiments disclosed herein are directed to a method of operating a heat pump to condition an interior space. In some embodiments, the method includes (a) circulating a refrigerant along a refrigerant circuit defined in an outdoor unit of the heat pump in a first direction to transfer heat from a thermal fluid flowing along a thermal fluid circuit to the refrigerant via a first heat exchanger and to transfer heat from the refrigerant to an ambient environment via a second heat exchanger. The refrigerant is a flammable refrigerant, and the second heat exchanger has a larger refrigerant volume than the first heat exchanger. In addition, the method includes (b) circulating the refrigerant along the refrigerant circuit in a second direction to transfer heat from the ambient environment to the refrigerant via the second heat exchanger and to transfer heat from the refrigerant to the thermal fluid via the first heat exchanger. Further, the method includes (c) transferring heat between the thermal fluid and the interior space via a third heat exchanger during (a) and (b). Still further, the method includes (d) collecting excess refrigerant in a charge compensator in fluid communication with the refrigerant circuit during (b); and (e) discharging the excess refrigerant from the charge compensator during (a).

Some embodiments are directed to a heat pump for conditioning an interior space. In some embodiments, the heat pump includes a thermal fluid circuit including a pump that is configured to circulate an aqueous fluid such that the aqueous fluid is maintained in a substantially liquid phase. In addition, the heat pump includes an outdoor unit including a vapor compression circuit contained in the outdoor unit that is configured to circulate a refrigerant, wherein the refrigerant comprises a flammable refrigerant, a compressor positioned along the vapor compression circuit that is configured to compress the refrigerant, a first heat exchanger positioned along the vapor compression circuit and the thermal fluid circuit that is configured to exchange heat between the refrigerant and the aqueous fluid, and a switchover valve that is configured to selectively circulate the refrigerant in a first direction to cool the aqueous fluid via the first heat exchanger and to circulate the refrigerant in a second direction to heat the aqueous fluid via the first heat exchanger. In addition, the outdoor unit includes a second heat exchanger positioned along the vapor compression circuit that is configured to exchange heat between the refrigerant and an outdoor environment surrounding the outdoor unit, wherein a refrigerant volume of the second heat exchanger is larger than a refrigerant volume of the first heat exchanger. Further, the outdoor unit includes a charge compensator positioned along the vapor compression circuit and configured to remove a volume of refrigerant from the vapor compression circuit when the refrigerant flows in the second direction and to permit a full volume of refrigerant in the vapor compression circuit when the refrigerant flows in the first direction. Also, the heat pump includes an air handler having a third heat exchanger that is positioned along the thermal fluid circuit and configured to exchange heat between the thermal fluid circuit and an airflow for the interior space.

Embodiments described herein comprise a combination of features and characteristics intended to address various shortcomings associated with certain prior devices, systems, and methods. The foregoing has outlined rather broadly the features and technical characteristics of the disclosed embodiments in order that the detailed description that follows may be better understood. The various characteristics and features described above, as well as others, will be readily apparent to those having ordinary skill in the art upon reading the following detailed description, and by referring to the accompanying drawings. It should be appreciated that this disclosure may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes as the disclosed embodiments. It should also be realized that such equivalent constructions do not depart from the spirit and scope of the principles disclosed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of various embodiments, reference will now be made to the accompanying drawings in which:

FIG. 1 is a schematic diagram of a climate control system that is configured to circulate a refrigerant having a low Global Warming Potential (GWP) according to some embodiments disclosed herein;

FIG. 2 is a schematic diagram of an embodiment of the climate control system of FIG. 1 operating in a heating mode according to some embodiments disclosed herein;

FIG. 3 is a schematic diagram of the climate control system of FIG. 2 operating in a cooling mode according to some embodiments disclosed herein;

FIG. 4 is a schematic diagram of a climate control system that is configured to circulate a refrigerant having a low GWP and operating in a heating mode according to some embodiments disclosed herein; and

FIG. 5 is a schematic diagram of the climate control system of FIG. 4 operating in a cooling mode according to some embodiments disclosed herein.

DETAILED DESCRIPTION

Traditional refrigerants, such as hydrofluorocarbons (HFCs), that have been used in climate control systems have been found to have a negative impact on the environment. As a result, there is a desire to develop climate control systems that may circulate more environmentally friendly refrigerants. Refrigerants that are of particular interests are those that have a reduced “Global Warming Potential” (GWP) rating. Low GWP refrigerants include flammable fluids, such as hydrocarbons (e.g., propane). However, the use of flammable GWP refrigerant in a traditional climate control system, especially in a climate control system that is configured for use in residential dwellings, presents additional challenges and safety concerns. As a result, there is a desire for new and innovative designs for a climate control system that may address these concerns, so that the overall environmental impacts of a climate control system may be reduced without sacrificing safety and functionality.

Accordingly, embodiments disclosed herein are directed to climate control systems that may circulate a potentially flammable and low GWP refrigerant to condition an interior space without exposing the interior space or its occupants to the refrigerant directly. For instance, some embodiments of a climate control system disclosed herein may include a plurality of fluid loops or circuits that are used to transfer heat between an interior space and an ambient environment while maintaining separation between a potentially flammable refrigerant and the interior space. In addition, some embodiments of the climate control systems disclosed herein may include additional adaptations that are configured to enhance functionality and efficiency of the multi-loop climate control system. Accordingly, through use of the embodiments disclosed herein, a climate control system may employ a more environmentally friendly refrigerant without sacrificing functionality or safety.

Referring now to FIG. 1, a climate control system 10 for conditioning an interior space 12 is shown according to some embodiments disclosed herein. The interior space 12 may include the interior space of a house or dwelling; however, as previously described, the interior space 12 may comprise any other suitable interior space that may be conditioned by a climate control system. For instance, the interior space 12 may comprise the interior space of a building, office, retail space, storage unit, refrigerator, freezer, etc. Specifically, the climate control system 10 may be configured to condition the interior space 12 by transferring heat between the interior space and an outdoor ambient environment 5 (or “outdoor environment” 5). The outdoor environment 5 may comprise an environment that at least partially surrounds the interior space 12. For instance, in the embodiment illustrated in FIG. 1, the interior space 12 is an interior space of a house 14, and the outdoor environment comprises the outdoor environment that surrounds the house 14.

The climate control system 10 may include an outdoor unit 50 and an indoor unit 70. The outdoor unit 50 may be positioned in the outdoor environment 5. Conversely, the indoor unit 70 may be positioned in an attic, storage room, basement, building, enclosure, that is proximate to, connected to, or at least partially integrated (or inside of) the interior space 12. However, it should be appreciated that the indoor unit 70 may be at least partially positioned and co-located in the outdoor environment 5 along with the outdoor unit 50 in some embodiments.

The climate control system 10 may include or define a plurality of fluid circuits or loops that are configured to transfer heat during operations. For instance, the climate control system 10 may include a first fluid circuit 60 that is at least partially positioned in the outdoor unit 5 and a second fluid circuit 72 that is thermally coupled to the first fluid circuit 60 and the indoor unit 70. During operation, the first fluid circuit 60 and the second fluid circuit 72 may circulate separate and distinct fluids (e.g., such as a refrigerant and a thermal fluid, respectively) in order to transfer heat between the outdoor environment 5 and the interior space 12. In some embodiments, the first fluid circuit 60 may comprise a vapor compression circuit configured to circulate a refrigerant such that the refrigerant is configured to undergo phase change (e.g., between the liquid and gas phases) to transfer heat during operations. On the other hand, in some embodiments, the second fluid circuit 72 may comprise a thermal fluid circuit configured to circulate a thermal fluid that is maintained in (or substantially maintained in) a liquid state to transfer heat during operations. Thus, the first fluid circuit 60 may be referred to herein as a “vapor compression circuit” or a “refrigerant circuit” 60 and the second fluid circuit 72 may be referred to herein as a “thermal fluid circuit” 72. The refrigerant circuit 60 may exchange heat with the outdoor environment 5, and the thermal fluid circuit 72 may exchange heat between the refrigerant circuit 60 and the interior space 12.

As previously described, the refrigerant circuit 60 is configured to circulate a refrigerant such that the refrigerant changes phase (e.g., from liquid to gas and from gas to liquid) to transfer heat between the outdoor environment 5 and the thermal fluid circuit 72 during operations. The refrigerant circuit 60 may be configured to circulate any suitable refrigerant, but may be particularly useful for circulating a low GWP refrigerant. Specifically, in some embodiments, the refrigerant circulated through the refrigerant circuit 60 of the outdoor unit 50 may comprise a flammable refrigerant, such as a hydrocarbon or hydrocarbon-based refrigerant (e.g., propane). Still other refrigerants are contemplated for use in the refrigerant circuit 60. For instance, in some embodiments, the refrigerant circulated in the refrigerant circuit 60 may comprise an A2L refrigerant including hydrofluoroolefins (HFOs) and blends thereof (e.g., R-1234fy, R-1234ze, R-452B, R-454B, etc.). Without being limited to this or any other theory, use of a flammable refrigerant in the refrigerant circuit 60 of outdoor unit 50 enhances safety by allowing leaked refrigerant to more easily vent and disperse to the atmosphere. Thus, by containing the refrigerant circuit 60 in the outdoor environment 5, the combustion risks associated with use of the flammable refrigerant may be reduced.

A plurality of heat exchangers may be coupled to the refrigerant circuit 60 to conduct heat transfer with the refrigerant during operations. Specifically, a first heat exchanger 44 may be configured to exchange heat between the refrigerant and the thermal fluid circulating along the thermal fluid circuit 72, and a second heat exchanger 32 may be configured to exchange heat between the refrigerant and the outdoor environment 5 via an airflow 40 that is generated by a first blower or fan 38.

A compressor 30 may be coupled to the refrigerant circuit 60 that is configured to circulate the refrigerant between the heat exchangers 32, 44. Valving (not shown in FIG. 1, but see switchover valve 28 in FIGS. 2-5) may be coupled to the refrigerant circuit 60 to allow the selective circulation of the refrigerant in a first direction 31 or an opposite second direction 33 along the refrigerant circuit 60. When flowing in the first direction 31, compressed refrigerant may be discharged from the compressor 30 to the second heat exchanger 32, and then may flow through the first heat exchanger 44 before returning to the compressor 30. Conversely, when flowing in the second direction 33, compressed refrigerant may be discharged from the compressor 30 to the first heat exchanger 44 and then may flow through the second heat exchange 32 before returning to the compressor 30. As will be described in more detail below, flowing the refrigerant in the first direction 31 may be configured to cool the thermal fluid of thermal fluid circuit 72 in the first heat exchanger 44 and flowing the refrigerant in the second direction 33 may be configured to heat the thermal fluid of the thermal fluid circuit 72 in the first heat exchanger 44.

Referring still to FIG. 1, the thermal fluid circuit 72 may be configured to circulate a thermal fluid between the first heat exchanger 44 coupled along the refrigerant circuit 60 and a third heat exchanger 74 of the indoor unit 70. Thus, the first heat exchanger 44 may be thermally coupled to both the refrigerant circuit 60 and the thermal fluid circuit 72. The third heat exchanger 74 may be configured to exchange heat between the thermal fluid and an airflow 76 that is directed to and through the interior space 12 during operations. The airflow 76 may be generated by a second blower or fan 58 of the indoor unit 70. In some embodiments, the indoor unit 70 may be broadly referred to herein as an “air handler.”

The thermal fluid may comprise any suitable fluid for transferring heat between the refrigerant (e.g., via first heat exchanger 44) and the airflow 76 (e.g., via third heat exchanger 74). In some embodiments, the thermal fluid may comprise an aqueous fluid, such as water or a water-glycol mixture. Still other fluids or fluid mixtures are contemplated for use as the thermal fluid circulated through the thermal fluid circuit 72, such as for instance, anti-freeze fluids including glycols, alcohols, organic/inorganic salts, etc.

A pump 78 may be coupled to the thermal fluid circuit 72. During operations, the pump 78 may be configured to circulate the thermal fluid along the thermal fluid circuit 72 between the first heat exchanger 44 and the third heat exchanger 74. In addition, an expansion tank 79 may be coupled to the thermal fluid circuit 72 that may be configured to receive an excess volume of thermal fluid that may result from thermal expansion, over-filling, etc.

Thus, in some embodiments, the thermal fluid may be circulated along the thermal fluid circuit 72 in a single direction via the pump 78. In addition, during operations, the thermal fluid may be maintained in (or substantially in) a liquid phase when circulating between the first heat exchanger 44 and the third heat exchanger 74. Thus, the thermal fluid circuit 72 may not utilize a phase change of the thermal fluid to facilitate the heat transfer to or from the thermal fluid during operations.

However, in some embodiments, the thermal fluid circuit 72 may be re-configured as a vapor compression circuit that is similar to the refrigerant circuit 60. For instance, in some embodiments, the thermal fluid circuit 72 configured as a vapor compression circuit may be configured to circulate a refrigerant, such as, for instance, carbon dioxide (CO₂), R32, an A2L refrigerant such as R1234yf, among others. If the thermal fluid of thermal fluid circuit 72 is configured as a vapor compression circuit, the refrigerant circulated in the thermal fluid circuit 72 may be different from the refrigerant used in the refrigerant circuit 60. In addition, in embodiments that configure the thermal fluid circuit 72 as a vapor compression circuit, the pump 78 may be replaced with a compressor (e.g., compressor 30) and one or more expansion devices (e.g., expansion devices 36, 42) may be included along the thermal fluid circuit to selectively expand the refrigerant as described herein.

In some embodiments, the climate control system 10 may comprise a so-called “heat pump,” that may be operated so as to either cool or heat the interior space 12 during operations. When operating in the “cooling mode” to cool the interior space 12, the compressor 30 may circulate the refrigerant in the first direction 31 along the refrigerant circuit 60. As a result, heat is transferred from the thermal fluid to the refrigerant in the first heat exchanger 44 (to thereby cool the thermal fluid of thermal fluid circuit 72), and then heat is transferred from the refrigerant to the airflow 40 in the second heat exchanger 32. The cooled thermal fluid discharged from the first heat exchanger 44 may be circulated to the third heat exchanger 74 to thereby cool the airflow 76 and ultimately the interior space 12.

Conversely, when operating in the heating mode to heat the interior space 12, the compressor 30 may circulate the refrigerant in the second direction 33 along the refrigerant circuit 60. As a result, heat is transferred from the outdoor environment 5 to the refrigerant in the second heat exchanger 32, and then heat is transferred from the refrigerant to the thermal fluid of the thermal fluid circuit 72 in the first heat exchanger 44. The heated thermal fluid discharged from the first heat exchanger 44 may then be circulated to the third heat exchanger 74 to thereby heat the airflow 76 and ultimately the interior space 12.

Each of the first heat exchanger 44 and the second heat exchanger 32 may define or have an internal volume for the refrigerant during operations. These internal volumes may be more simply referred to herein as the “refrigerant volumes” of the heat exchangers 32, 44. Thus, the refrigerant volume of the heat exchangers 32, 44 may define the maximum volume that may be held within the heat exchanger 32, 44 at any given time during operations.

The thermal heat transfer between the thermal fluid of the thermal fluid circuit 72 and the refrigerant of the refrigerant circuit 60 in the first heat exchanger 44 may be more efficient than the heat transfer between the airflow 40 and the refrigerant in the second heat exchanger 32. As a result, the refrigerant volume of the first heat exchanger 44 may be less than the refrigerant volume of the second heat exchanger 32 so that the heat transfer rates of the heat exchangers 32, 44 may be equivalent or at least correspond to one another during operation of the climate control system 10 in both the heating mode and cooling modes. For instance, in some embodiments, the refrigerant volume of the second heat exchanger 32 may be about two (2) to about ten (10) times greater than the refrigerant volume of the first heat exchanger 44.

In addition, when operating the climate control system 10 in the cooling mode, the refrigerant may be in a substantially vapor state in the first heat exchanger 44 and may be in a substantially liquid state in the second heat exchanger 32. Conversely, when operating the climate control system 10 in the heating mode, the refrigerant may be in a substantially vapor state in the second heat exchanger 32 and may be in a substantially liquid state in the first heat exchanger 44. As is understood to one having ordinary skill, a constant mass of refrigerant may occupy a much larger volume when in the vapor state as opposed to the liquid state. Moreover, in order to ensure proper functioning and efficient heat transfer during the cooling mode operation, the charge of refrigerant in the refrigerant circuit 60 may be selected to sufficiently fill a desired portion of the refrigerant volume of the second heat exchanger 32 with liquid refrigerant. As a result, the refrigerant circuit 60 may operate with a substantial overcharge of refrigerant with respect to the heating mode operation. Namely, the liquid volume of refrigerant that may flow through the smaller first heat exchanger 44 may be far greater than the refrigerant volume of the first heat exchanger 44, which may result in a reduction in the operating efficiency of the climate control system 10. This problem is further exacerbated by the relatively large difference in the refrigerant volumes of the heat exchangers 32, 44 necessitated by the differences in the heat exchange efficiencies of the heat exchangers 32, 44.

Thus, the climate control system 10, and particularly the refrigerant circuit 60, may include additional features that effectively mitigate the refrigerant overcharge during a heating mode operation without sacrificing efficiency and functionality of the climate control system 10 during the cooling mode operation. For instance, the climate control system 10 may include a charge compensator 110 that is in fluid communication with the refrigerant circuit 60 and configured to selectively receive and discharge the volume of excess refrigerant flowing in the refrigerant circuit 60 during operations. The charge compensator 110 is generally shown coupled to the refrigerant circuit 60 between the first heat exchanger 44 and second heat exchanger 32 so that excess refrigerant may be diverted out of or delivered to the refrigerant circuit 60 between the heat exchangers 32, 44 during operations. However, as will be described in more detail below, the charge compensator 110 may be coupled to the refrigerant circuit 60 in a number of different ways. Further aspects of embodiments of the climate control system 10 and charge compensator 110 will now be described below.

Referring now to FIGS. 2 and 3, a schematic diagram of the climate control system 10 is shown that illustrates further details according to some embodiments. FIG. 2 illustrates the climate control system 10 operating in a heating mode, and FIG. 3 illustrates the climate control system 10 operating in a cooling mode.

A switchover valve 28 may be coupled to the refrigerant circuit 60 that is configured to actuate to selectively change a flow direction of the refrigerant during operations (e.g., between the first direction 31 and second direction 33 generally illustrated in FIG. 1). Specifically, the switchover valve 28 may be actuatable between a first position to facilitate the heating mode operation shown in FIG. 2 and a second position to facilitate the cooling mode operation shown in FIG. 3. Thus, in the first position (FIG. 2), the switchover valve 28 may direct compressed refrigerant discharged from the compressor 30 to the first heat exchanger 44 (such as described for the second direction 33 in FIG. 1), and in the second position (FIG. 3), the switchover valve 28 may direct compressed refrigerant discharged from the compressor 30 to the second heat exchanger 32 (such as described for the first direction 31 in FIG. 1).

A fourth heat exchanger 90 may be coupled to the refrigerant circuit 60 between the compressor 30 and the switchover valve 28. During operation, warm, compressed refrigerant may flow through the fourth heat exchanger before flowing through the switchover valve 28. The fourth heat exchanger 90 may be configured to transfer heat from the refrigerant to a hot water supply 92 that may be utilized in the interior space 12 or elsewhere. Thus, the fourth heat exchanger 90 may be referred to as a “water heater.”

In addition, the climate control system 100 may include a first expansion device 42 and a second expansion device 36 positioned along a liquid refrigerant line 114 of the refrigerant circuit 60 that extends between the heat exchangers 32, 44. For instance the first expansion device 42 may be positioned between the first heat exchanger 44 and the second expansion device 36 along the refrigerant circuit 60, and the second expansion device 36 may be positioned between the second heat exchanger 32 and the first expansion device 42.

The first expansion device 42 and second expansion device 36 may comprise orifices or expansion valves, such as electronic expansion valves (EEVs) that are actuated by a controller. Alternatively, the first expansion device 42 and the second expansion device 36 may comprise thermostatic expansion valves (TXV) that are configured to adjust in position (that is, in opening position) in response to one or more pressures and/or temperatures of the refrigerant flowing in the fluid circuit 60 (or a portion thereof).

When the climate control system 100 is operating in the heating mode (FIG. 2), the first expansion device 42 may be opened or bypassed so as to not restrict the flow of refrigerant therethrough, and the second expansion device 36 may expand the refrigerant into a mixed phase flow of liquid and vapor before the refrigerant flows into the second heat exchanger 32. Thereafter, within the second heat exchanger 32, the refrigerant may fully (or substantially) transition into a vapor via the heat transferred to the refrigerant from the airflow 40.

Conversely, when the climate control system 100 is operating in the cooling mode (FIG. 3), the second expansion device 36 may be opened or bypassed so as to not restrict the flow of refrigerant therethrough, and the first expansion device 42 may expand the refrigerant into a mixed phase flow of liquid and vapor before the refrigerant flows into the first heat exchanger 44. Thereafter, within the first heat exchanger 44, the refrigerant may fully (or substantially) transition into a vapor via the heat transferred to the refrigerant from the thermal fluid flowing along thermal fluid circuit 72.

The charge compensator 110 may include a chamber 111 and an inner flow tube 113 extending through the chamber 111. The inner flow tube 113 may define a flow path that is separate from the chamber 111 so that refrigerant flowing through the inner flow tube 113 may not be in fluid communication with refrigerant stored in the chamber 111. However, heat may freely transfer between the refrigerant flowing in the inner flow tube 113 and any refrigerant stored in the chamber 111 during operations.

As shown in FIGS. 2 and 3, the inner flow tube 113 of charge compensator 110 is positioned along a vapor refrigerant line 116 of the refrigerant circuit 60 that extends between the switchover valve 28 and the second heat exchanger 32. Thus, during the heating mode operation (FIG. 2), refrigerant may flow along the vapor refrigerant line 116 from the second heat exchanger 32, through the inner flow tube 113 of charge compensator 110, and then to the switchover valve 28. Conversely, during the cooling mode operation (FIG. 3), the refrigerant may flow along the vapor refrigerant line 116 from the switchover valve 28, through the inner flow tube 113 of the charge compensator 110, and then into the second heat exchanger 32.

The chamber 111 of charge compensator 110 may be configured to selectively hold a volume of liquid refrigerant therein to account for the differences in refrigerant volumes of the heat exchangers 32, 44 as previously described. A refrigerant line 112 may connect between the chamber 111 of the charge compensator and the refrigerant line 114 at a point that is between the first and second expansion devices 42, 36, respectively.

During a heating mode operation (FIG. 2), compressed vapor refrigerant that is discharged from the compressor 30 is directed to the first heat exchanger 44 via the switchover valve 28. In the first heat exchanger 44, heat is transferred from the refrigerant to the thermal fluid flowing along the thermal fluid circuit 72, so that the vaporous refrigerant is condensed (or substantially condensed) into a liquid. The liquid (or semi-liquid) refrigerant is then discharged from the first heat exchanger 44 and is advanced past the first expansion device 42 (which is open or bypassed so as not to meter or restrict the flow of refrigerant as previously described) and then on toward the second expansion device 36. A portion of the liquid (or semi-liquid) refrigerant may be diverted to the chamber 111 of the charge compensator 110 along the refrigerant line 112, and a remaining portion of the liquid (or semi-liquid) refrigerant may be expanded by the second expansion device 36 into a cool mixed phase refrigerant that is then directed through the second heat exchanger 32. Within the second heat exchanger 32, the refrigerant may absorb heat from the airflow 40 and may fully transition to a vapor which is then discharged and flowed through the inner flow tube 113 of charge compensator 110 enroute to the compressor 30 via the switchover valve 28. The refrigerant discharged from the second heat exchanger 32 and flowed through the inner flow tube 113 of charge compensator 110 may be vaporized but still relatively cool so as to avoid vaporizing the refrigerant stored in the chamber 111 during the heating mode operation of FIG. 2.

Thus, during the heating mode operation (FIG. 2), a portion (or volume) of the refrigerant may be stored in the chamber 111 of charge compensator 110 via the refrigerant line 112 so that the refrigerant circuit 60 is not overcharged relative to the smaller, first heat exchanger 44. Without being limited to this or any other theory, if the excess refrigerant were not stored in the chamber 111 of charge compensator 110 during the heating mode operation (FIG. 2) as described, the increased refrigerant volume circulating along the refrigerant circuit 60 during the heating mode operation (FIG. 2) may cause excessive subcooling in the second heat exchanger 32, increased pressures along the refrigerant circuit 60, and increased power consumption by the compressor 30.

The flow of refrigerant into the chamber 111 of charge compensator 110 during the heating mode operation of FIG. 2 may be controlled via a valve positioned along the refrigerant line 112 in some embodiments. In other embodiments, the flow of refrigerant along refrigerant line 112 may be generally unrestricted via valves or other flow control devices. For instance, in some embodiments, when the chamber 111 of charge compensator 110 fills to capacity, a back pressure is exerted on the refrigerant line 112 that may prevent (or at least restrict) the continued flow of refrigerant into the charge compensator 110 via the refrigerant line 112. Thus, the volume of the chamber 111 of charge compensator 110 may dictate the amount of refrigerant that is removed from circulation between the heat exchangers 32, 44 during the heating mode operation (FIG. 2). As such, the volume of the chamber 111 of charge compensator 110 may be selected to correspond to the refrigerant volumes of the heat exchangers 32, 44.

Conversely, during a cooling mode operation (FIG. 3), compressed vapor refrigerant that is discharged from the compressor 30 is directed through the inner flow tube 113 of charge compensator 110 and then on toward the second heat exchanger 32 via the vapor refrigerant line 116 and switchover valve 28. Within the second heat exchanger 32, the vapor refrigerant may lose heat to the airflow 40, so that the refrigerant is at least partially condensed to a liquid that is then discharged into the liquid line 114. The liquid (or semi-liquid) refrigerant is then flowed past the second expansion device 36 (which is open or bypassed so as not to meter or restrict the flow of refrigerant as previously described) and then on toward the first expansion device 42.

In addition, the heat of the refrigerant flowing in the inner flow tube 113, upstream of the second heat exchange 32, may vaporize the liquid refrigerant stored in the chamber 111 of charge compensator 110 so that the excess refrigerant stored in the chamber 111 may flow back into the refrigerant circuit 60 via the refrigerant line 112 to thereby merge with the flow of refrigerant discharged from the second heat exchanger 32 and flowed past the second expansion device 36. The combined refrigerant flow is then expanded through the first expansion device 42 into a cool mixed phase refrigerant that is then directed through the first heat exchanger 44. Within the first heat exchanger 44, the refrigerant may absorb heat from the thermal fluid of the thermal fluid loop 72 to thereby cool the thermal fluid and heat the refrigerant. As a result, within the first heat exchanger 44, the refrigerant may fully transition to a vapor that is then discharged to the compressor 30 via the switchover valve 28.

Thus, during the cooling mode operation (FIG. 3), the excess refrigerant stored in the chamber 111 of charge compensator 110 may be re-distributed into the refrigerant circuit 60 via the refrigerant line 112. As a result, the larger second heat exchanger 32 may be sufficiently charged with liquid refrigerant to ensure efficient heat transfer during the cooling mode operation.

Referring now to FIGS. 4 and 5, an embodiment of a climate control system 100 for conditioning the interior space 12 is shown that may be used in place of the embodiments of climate control system 10 shown in FIGS. 1-3. The climate control system 100 may include a number of features that are shared with the climate control system 10. Thus, the same reference numbers are used to refer to the features of climate control system 100 that are shared with climate control system 10, and the description below will focus on the features of climate control system 100 that are different from the climate control system 10.

FIG. 4 illustrates the climate control system 100 operating in a heating mode. Conversely, FIG. 5 illustrates the climate control system 100 operating in a cooling mode.

As shown in FIGS. 4 and 5, for the climate control system 100, the charge compensator 110 is not positioned along the vapor refrigerant line 116. Rather, the charge compensator is positioned along a separate refrigerant line 120 that is connected to the liquid refrigerant line 114 as a bypass around the first expansion device 42. Specifically, the refrigerant line 120 may extend from a first connection point 120a along the liquid refrigerant line 114 that is between the first expansion device 42 and the first heat exchanger 44, to a second connection point 120b along the liquid refrigerant line 114 that is between the first expansion device 42 and the second expansion device 36.

A first check valve 122 may be positioned along the liquid refrigerant line 114 between the first expansion device 42 and the second connection point 120b. In addition, a second check valve 124 may be positioned along the refrigerant line 120, between the charge compensator 110 and the second connection point 120b. The first check valve 122 may be configured to allow refrigerant to advance from the second connection point 120b to the first expansion device 42 but may prevent refrigerant flow from flowing back from the first expansion device 42 to the second connection point 120b. Likewise, the second check valve 124 may be configured to allow refrigerant to flow from the charge compensator 110 to the second connection point 120b via the refrigerant line 120, but may prevent the flow of refrigerant from the second connection point 120b to the charge compensator 110 along refrigerant line 120.

As previously described for the climate control system 10, the charge compensator 110 may be configured to selectively store excess refrigerant so that refrigerant circuit 60 is not overcharged relative to the smaller first heat exchanger 44 during a heating mode operation while still allowing a sufficient volume of liquid refrigerant to charge the larger second heat exchanger 32 during a cooling mode operation. Specifically, during a heating mode operation (FIG. 4), compressed vapor refrigerant that is discharged from the compressor 30 is directed to the first heat exchanger 44 via the switchover valve 28. In the first heat exchanger 44, heat is transferred from the refrigerant to the thermal fluid flowing along the thermal fluid circuit 72, so that the vaporous refrigerant is condensed (or substantially condensed) into a liquid. The liquid (or semi-liquid) refrigerant is then discharged from the first heat exchanger 44 and is advanced toward the first expansion device 42. However, the first check valve 122 prevents the refrigerant from flowing through the first expansion device 42, and instead directs the liquid (or semi-liquid) refrigerant into the refrigerant line 120 via the first connection point 120a and through the charge compensator 110 before being returned to the liquid refrigerant line 114 via the second connection point 120b. A portion of the liquid (or semi-liquid) refrigerant may be collected in the charge compensator 110 so that a reduced flow of refrigerant is returned to the liquid refrigerant line 114 via the second connection point 120b. The refrigerant flowing back into the liquid refrigerant line 114 is then expanded via the second expansion device 36 and heated in the second heat exchanger 32 via contact with the airflow 40 as previously described. Thus, during the heating mode operation (FIG. 4), a portion of the refrigerant may be held in the charge compensator 110 so that the smaller, first heat exchanger 44 is not overcharged with liquid refrigerant as previously described.

Conversely, during a cooling mode operation (FIG. 5), compressed vapor refrigerant that is discharged from the compressor 30 is directed toward the second heat exchanger 32 via the switchover valve 28 and vapor refrigerant line 116. Within the second heat exchanger 32, the vapor refrigerant may lose heat to the airflow 40, so that the refrigerant is at least partially condensed to a liquid that is then discharged into the liquid line 114. The liquid (or semi-liquid) refrigerant is then flowed past the second expansion device 36 (which is open or bypassed so as not to meter or restrict the flow of refrigerant as previously described) and then on toward the first expansion device 42.

Refrigerant that is advanced past the second expansion device 36 in the liquid line 114 may be prevented from flowing into the refrigerant line 120 via the second connection point 120b by the second check valve 124. However, the first check valve 122 may allow refrigerant to flow from the second expansion device 36 to the first expansion device 42 along the liquid line 114. The expansion of the refrigerant through the first expansion device 42 and the relatively lower temperature of the refrigerant in the first heat exchanger 44 may generate a pressure differential that draws refrigerant out of the charge compensator 110 back into the liquid line 114 via the second check valve 124 and second connection point 120b. Thus, the refrigerant drawn out of the charge compensator 110 may also be expanded through the first expansion device 42. Within the first heat exchanger 44, the refrigerant may absorb heat from the thermal fluid of the thermal fluid loop 72 to thereby cool the thermal fluid and heat the refrigerant. As a result, within the first heat exchanger 44, the refrigerant may fully transition to a vapor that is then discharged to the compressor 30 via the switchover valve 28.

Thus, during the cooling mode operation (FIG. 5), the volume of excess refrigerant that is stored in the charge compensator 110 may be re-distributed into the refrigerant circuit 60 via the refrigerant line 112. As a result, the larger second heat exchanger 32 may be sufficiently charged with liquid refrigerant to ensure efficient heat transfer during the cooling mode operation.

Moreover, as previously described, the refrigerant is routed through the charge compensator 110 before flowing on to the second expansion device 36 when operating the climate control system 100 in the heating mode (FIG. 4). Thus, the charge compensator 110 may be connected in series between the first heat exchanger 44 and the second heat exchanger 32 when operating the climate control system 100 in the heating mode (FIG. 4). However, as is also previously described, the first heat exchanger 44 may receive refrigerant from both the charge compensator 110 and the second heat exchanger 32 during the cooling mode (FIG. 5), until the charge compensator 110 is emptied. Thus, the charge compensator 110 may be connected in parallel with the second heat exchanger 32, upstream of the first heat exchanger 44 along the refrigerant circuit 60 in the cooling mode (FIG. 5).

As explained above and reiterated below, the present disclosure includes, without limitation, the following example implementations.

Clause 1: A heat pump for conditioning an interior space, the heat pump comprising: a thermal fluid circuit that is configured to circulate a thermal fluid; an outdoor unit comprising: a refrigerant circuit that is configured to circulate a refrigerant to cool the thermal fluid during a cooling mode of the heat pump and to heat the thermal fluid during a heating mode of the heat pump; a first heat exchanger positioned along the refrigerant circuit that is configured to exchange heat between the refrigerant and the thermal fluid; a second heat exchanger positioned along the refrigerant circuit that is configured to exchange heat between the refrigerant of the refrigerant circuit and an outdoor environment surrounding the outdoor unit, wherein a refrigerant volume of the second heat exchanger is larger than a refrigerant volume of the first heat exchanger; and a charge compensator positioned along the refrigerant circuit that is configured to receive excess refrigerant therein when the heat pump operates in the heating mode and configured to discharge the excess refrigerant to the refrigerant circuit when the heat pump operates in the cooling mode; and an air handler having a third heat exchanger that is configured to exchange heat between the thermal fluid circuit and an airflow for the interior space.

Clause 2: The heat pump of any of the clauses, wherein the refrigerant volume of the second heat exchanger is two to ten times greater than the refrigerant volume of the first heat exchanger.

Clause 3: The heat pump of any of the clauses, wherein the refrigerant is a flammable refrigerant.

Clause 4: The heat pump of any of the clauses, wherein the refrigerant comprises propane.

Clause 5: The heat pump of any of the clauses, wherein the thermal fluid comprises an aqueous fluid.

Clause 6: The heat pump of any of the clauses, further comprising a fourth heat exchanger positioned along the refrigerant circuit that is configured to exchange heat between the refrigerant and a hot water supply for the interior space.

Clause 7: The heat pump of any of the clauses, wherein the refrigerant circuit comprises a vapor compression circuit in which the refrigerant is configured to undergo phase change during circulation, and wherein the outdoor unit further comprises: a compressor that is configured to pressurize the refrigerant along the refrigerant circuit; and a switchover valve that is actuatable to selectively flow the refrigerant in a first direction along the refrigerant circuit during the cooling mode, and to flow the refrigerant in a second direction along the refrigerant circuit during the heating mode.

Clause 8: The heat pump of any of the clauses, further comprising a pump positioned along the thermal fluid circuit that is configured to pressurize the thermal fluid.

Clause 9: The heat pump of any of the clauses, wherein the charge compensator is positioned along the refrigerant circuit such that: during the heating mode, the charge compensator is connected in series between the first heat exchanger and the second heat exchanger; and during the cooling mode, the charge compensator is connected in parallel with the second heat exchanger, upstream of the first heat exchanger.

Clause 10: A method of operating a heat pump to condition an interior space, the method comprising: (a) circulating a refrigerant along a refrigerant circuit defined in an outdoor unit of the heat pump in a first direction to transfer heat from a thermal fluid flowing along a thermal fluid circuit to the refrigerant via a first heat exchanger and to transfer heat from the refrigerant to an ambient environment via a second heat exchanger, wherein the refrigerant circuit is a vapor compression circuit, wherein the refrigerant is a flammable refrigerant, and wherein the second heat exchanger has a larger refrigerant volume than the first heat exchanger; (b) circulating the refrigerant along the refrigerant circuit in a second direction to transfer heat from the ambient environment to the refrigerant via the second heat exchanger and to transfer heat from refrigerant to the thermal fluid via the first heat exchanger; (c) circulating the thermal fluid substantially in a liquid phase between the first heat exchanger and a third heat exchanger during (a) and (b) to transfer heat between the thermal fluid and the interior space; (d) collecting excess refrigerant from the refrigerant circuit in a charge compensator in fluid communication with the refrigerant circuit during (b); and (e) discharging the excess refrigerant to the refrigerant circuit from the charge compensator during (a).

Clause 11: The method of any of the clauses, further comprising: (f) transferring heat from the refrigerant to a hot water supply for the interior space by use of a fourth heat exchanger that is thermally coupled to the refrigerant circuit.

Clause 12: The method of any of the clauses, wherein (d) comprises flowing the refrigerant from the first heat exchanger, through the charge compensator, and then through the second heat exchanger to collect the excess refrigerant in the charge compensator.

Clause 13: The method of any of the clauses, wherein (e) comprises flowing refrigerant out of the charge compensator in parallel with refrigerant discharged from the second heat exchanger.

Clause 14: The method of any of the clauses, wherein (e) further comprises: (e1) merging refrigerant flowing out of the charge compensator with refrigerant discharged from the second heat exchanger to form a combined refrigerant flow; and (e2) expanding the combined refrigerant flow upstream of the first heat exchanger.

Clause 15: A heat pump for conditioning an interior space, the heat pump comprising: a thermal fluid circuit including a pump that is configured to circulate an aqueous fluid such that the aqueous fluid is maintained in a substantially liquid phase; an outdoor unit comprising: a vapor compression circuit contained in the outdoor unit that is configured to circulate a refrigerant, wherein the refrigerant comprises a flammable refrigerant; a compressor positioned along the vapor compression circuit that is configured to compress the refrigerant; a first heat exchanger positioned along the vapor compression circuit and the thermal fluid circuit that is configured to exchange heat between the refrigerant and the aqueous fluid; a switchover valve that is configured to selectively circulate the refrigerant in a first direction to cool the aqueous fluid via the first heat exchanger and to circulate the refrigerant in a second direction to heat the aqueous fluid via the first heat exchanger; a second heat exchanger positioned along the vapor compression circuit that is configured to exchange heat between the refrigerant and an outdoor environment surrounding the outdoor unit, wherein a refrigerant volume of the second heat exchanger is larger than a refrigerant volume of the first heat exchanger; and a charge compensator positioned along the vapor compression circuit and configured to remove a volume of refrigerant from the vapor compression circuit when the refrigerant flows in the second direction and to permit a full volume of refrigerant in the vapor compression circuit when the refrigerant flows in the first direction; and an air handler having a third heat exchanger that is positioned along the thermal fluid circuit and configured to exchange heat between the thermal fluid circuit and an airflow for the interior space.

Clause 16: The heat pump of any of the clauses, wherein the charge compensator is positioned along the vapor compression circuit such that when the refrigerant circulates in the second direction, the charge compensator is connected in series between the first heat exchanger and the second heat exchanger along the vapor compression circuit.

Clause 17: The heat pump of any of the clauses, wherein the charge compensator is positioned along the vapor compression circuit such when the refrigerant circulates in the first direction, the charge compensator is connected in parallel with the second heat exchanger, upstream of the first heat exchanger along the vapor compression circuit.

Clause 18: The heat pump of any of the clauses, further comprising: a first expansion device and a second expansion device positioned along a liquid line of the vapor compression circuit that extends between the first heat exchanger and the second heat exchanger, wherein the first expansion device is positioned along the liquid line between the second expansion device and the first heat exchanger; and a bypass line that extends from a first point along the liquid line that is between the first expansion device and the first heat exchanger to a second point along the liquid line that is between the first expansion device and the second expansion device, wherein the charge compensator is positioned along the bypass line.

Clause 19: The heat pump of any of the clauses, further comprising: a first check valve positioned along the liquid line between the second point and the first expansion device, the first check valve being configured to allow refrigerant flow along the liquid line from the second expansion device to the first expansion device and to prevent refrigerant flow along the liquid line from the first expansion device to the second expansion device; and a second check valve positioned along the bypass line between the charge compensator and the second point, the second check valve being configured to allow refrigerant flow along the bypass line from the charge compensator to the second point and to prevent refrigerant flow along the bypass line from the second point to the charge compensator.

Clause 20: The heat pump of any of the clauses, wherein the refrigerant volume of the second heat exchanger is two to ten times greater than the refrigerant volume of the first heat exchanger.

Clause 21: The heat pump of any of the clauses, further comprising a fourth heat exchanger positioned along the vapor compression circuit that is configured to exchange heat between the refrigerant and a hot water supply for the interior space.

Embodiments disclosed herein are directed to climate control systems that may circulate a potentially flammable and low GWP refrigerant to condition an interior space without exposing the interior space or its occupants to the refrigerant directly. For instance, some embodiments of a climate control system disclosed herein may include a plurality of fluid loops or circuits that are used to transfer heat between an interior space and an ambient environment while maintaining separation between a potentially flammable refrigerant and the interior space. In addition, some embodiments of the climate control systems disclosed herein may include additional adaptations that are configured to enhance functionality and efficiency of the multi-loop climate control system. Accordingly, through use of the embodiments disclosed herein, a climate control system may employ a more environmentally friendly refrigerant without sacrificing functionality or safety.

While embodiments disclosed herein have described climate control systems that heat or cool a thermal fluid flowing along a thermal fluid circuit 72 to heat or cool an airflow 76 for an interior space 12, it should be appreciate that the heated or cooled thermal fluid (or another thermal fluid circuit) may be used to deliver heat to or from other assemblies or systems. For instance, in some embodiments, a climate control system according to embodiments disclosed herein may heat or cool a thermal fluid of a thermal fluid circuit (e.g., thermal fluid circuit 72) so that the thermal fluid may be used to heat or cool a radiant heating system, such as a radiant heating or cooling system installed in the floor of a house 14 (or other structure).

The preceding discussion is directed to various exemplary embodiments. However, one of ordinary skill in the art will understand that the examples disclosed herein have broad application, and that the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to suggest that the scope of the disclosure, including the claims, is limited to that embodiment.

The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.

In the discussion herein and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . .” Also, the term “couple” or “couples” is intended to mean either an indirect or direct connection. Thus, if a first device couples to a second device, that connection may be through a direct connection of the two devices, or through an indirect connection that is established via other devices, components, nodes, and connections. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a given axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the given axis. For instance, an axial distance refers to a distance measured along or parallel to the axis, and a radial distance means a distance measured perpendicular to the axis. Further, when used herein (including in the claims), the words “about,” “generally,” “substantially,” “approximately,” and the like, when used in reference to a stated value mean within a range of plus or minus 10% of the stated value.

While exemplary embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the scope or teachings herein. The embodiments described herein are exemplary only and are not limiting. Many variations and modifications of the systems, apparatus, and processes described herein are possible and are within the scope of the disclosure. Accordingly, the scope of protection is not limited to the embodiments described herein, but is only limited by the claims that follow, the scope of which shall include all equivalents of the subject matter of the claims. Unless expressly stated otherwise, the steps in a method claim may be performed in any order. The recitation of identifiers such as (a), (b), (c) or (1), (2), (3) before steps in a method claim are not intended to and do not specify a particular order to the steps, but rather are used to simplify subsequent reference to such steps.