Systems and methods for defrosting an outdoor heat exchanger of a heat pump

Abstract

An embodiment of a thermal storage module installable on a climate control system. The thermal storage module is an independent device that can be mountable between an outdoor unit and an indoor unit of the climate control system. The thermal storage module may include a fluid tank, a fluid pump, a heat exchanger for exchanging thermal energy between the working fluid and a refrigerant flow within the refrigerant circuit, an expansion valve and a solenoid valve, and a controller. The fluid pump is activated when the climate control system is operating in a heating mode and a defrost mode and is deactivated when the climate control system is operating in a cooling mode. The operation of the expansion valve and solenoid valve depends on the operation mode (cooling / heating / defrosting) of the main climate control system.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Continuation-in-part Application of U.S. patent application Ser. No. 18 / 809,539 filed Aug. 20, 2024, and entitled “SYSTEMS AND METHODS FOR DEFROSTING AN OUTDOOR HEAT EXCHANGER OF A HEAT PUMP”, the entire contents of which is incorporated herein by reference.BACKGROUND

[0002] A heat pump may be used to heat an interior space by circulating a refrigerant between a pair of heat exchangers. The interior space may be an interior space of a house, apartment, building, retail store, storage unit, office, refrigerator, freezer, vehicle, etc. Specifically, the refrigerant may be circulated between a first heat exchanger that is configured to transfer heat from an outdoor environment to the refrigerant and a second heat exchanger that is configured to transfer heat from the refrigerant to the interior space.BRIEF SUMMARY

[0003] Some embodiments disclosed herein are directed to a heat pump for conditioning an interior space. In some embodiments, the heat pump includes an outdoor unit including an outdoor heat exchanger that is configured to exchange heat between a refrigerant and an outdoor environment, and an outdoor expansion device that is configured to expand the refrigerant flowing into the outdoor heat exchanger when the heat pump is operating in a heating mode. In addition, the heat pump includes an indoor unit including an indoor heat exchanger that is configured to exchange heat between the refrigerant and the interior space, and an indoor expansion device that is configured to expand the refrigerant flowing into the indoor heat exchanger when the heat pump is operating in a defrost mode. Further, the heat pump includes a thermal storage device in fluid communication between the outdoor expansion device and the indoor expansion device. Still further, the heat pump includes a reversing valve that is actuatable between: a first position during the heating mode to direct refrigerant through the indoor heat exchanger, the thermal storage device, the outdoor expansion device, and then the outdoor heat exchanger to heat the interior space and to transfer heat from the refrigerant to the thermal storage device; and a second position during the defrost mode to direct refrigerant through the outdoor heat exchanger and then the thermal storage device to transfer thermal energy to the outdoor heat exchanger from the thermal storage device.

[0004] Some embodiments disclosed herein are directed to a method of operating a heat pump to condition an interior space, the heat pump including an outdoor heat exchanger to exchange heat between a refrigerant and an outdoor environment, an outdoor expansion device, an indoor heat exchanger to exchange heat between the refrigerant and the interior space, and an indoor expansion device. In some embodiments, the method includes routing the refrigerant through the indoor heat exchanger, a thermal storage device, the outdoor expansion device, and then an outdoor heat exchanger to heat the interior space via the indoor heat exchanger and to transfer heat from the refrigerant to the thermal storage device, the thermal storage device being in fluid communication between the indoor expansion device and the outdoor expansion device. In addition, the method includes routing the refrigerant through the outdoor heat exchanger and then the thermal storage device to transfer thermal energy to the outdoor heat exchanger from the thermal storage device.

[0005] Some embodiments disclosed herein are directed to a heat pump for conditioning an interior space. In some embodiments, the heat pump includes an outdoor unit including an outdoor heat exchanger that is configured to exchange heat between a refrigerant and an outdoor environment. In addition, the heat pump includes an indoor unit including an indoor heat exchanger that is configured to exchange heat between the refrigerant and the interior space, an indoor expansion device that is configured to expand the refrigerant, and a thermal storage device that is configured to exchange heat between the refrigerant and a thermal storage medium. Further, the heat pump includes valving that is actuatable to operate the heat pump in: a heating mode in which refrigerant is flowed through the indoor heat exchanger and the thermal storage device in parallel and then is flowed to the outdoor unit to heat the interior space via the indoor heat exchanger and to transfer heat from the refrigerant to the thermal storage medium of the thermal storage device; and a defrost mode in which refrigerant is flowed through the outdoor heat exchanger and then is flowed through the thermal storage device in bypass of the indoor heat exchanger to transfer heat from the thermal storage medium of the thermal storage device to the outdoor heat exchanger.

[0006] Some embodiments disclosed herein are directed to a thermal storage module. The thermal storage module may be in fluid communication with an outdoor unit and an indoor unit of a climate control system. The climate control system may include a refrigerant circuit for directing a refrigerant flowing between the indoor unit and the outdoor unit. The outdoor unit may include a compressor. The thermal storage module may include a fluid tank containing a thermal energy storage fluid as well as a fluid pump configured to circulate a working fluid through the fluid tank. The working fluid may be configured to or selected to exchange thermal energy with the thermal energy storage fluid.

[0007] The thermal storage module may also include a heat exchanger fluidly coupled to the refrigerant circuit between the outdoor unit and the indoor unit. The heat exchanger may be configured to exchange thermal energy between the working fluid and a refrigerant flow within the refrigerant circuit. The thermal storage modules may also include an expansion valve coupled to the refrigerant circuit between the heat exchanger and the outdoor unit. In some embodiments, the thermal storage module may also include a controller configured to control the fluid pump based on an operation mode of the climate control system. The fluid pump may be configured to be activated when the climate control system is operating in a heating mode or in a defrosting mode, and may be configured to be deactivated when the climate control system is operating in a cooling mode. In some embodiments, the thermal storage module may be separate from the indoor unit and the outdoor unit and located along the refrigerant circuit therebetween. In at least certain embodiments, the thermal energy storage fluid may be a phase-change material.

[0008] In some embodiments, the controller of the thermal storage module may be configured to activate or deactivate the fluid pump based on mode of operation signals received from the climate control system. In some embodiments, the thermal storage module may further include a solenoid valve coupled to the refrigerant circuit between the heat exchanger and the indoor unit. The solenoid valve may be configured to bypass the refrigerant such that the refrigerant is prevented from flowing into the indoor unit when the climate control system is in a defrost mode. The controller of the thermal storage module may be configured to open or close the expansion valve and the solenoid valve based on an operation mode of the control system. The operation mode may be selected from heating mode, cooling mode, and defrost mode. Upon receiving a control signal from the climate control system that the climate control system is operating in heating mode, the controller may be configured to open the expansion valve and close the solenoid valve. Upon receiving a control signal from the climate control system that the climate control system is operating in cooling mode, the controller may be configured to open the expansion valve and close the solenoid valve. Upon receiving a control signal from the climate control system that the climate control system is operating in defrost mode, the controller may be configured to open the expansion valve and open the solenoid valve.

[0009] In some embodiments, the thermal storage module is configured such that when the climate control system is in a heating mode, the expansion valve is opened and the solenoid valve is closed, and the refrigerant is directed from the compressor along the refrigerant circuit to the indoor coil of the indoor unit, the heat exchanger of the thermal storage module, the outdoor coil of the outdoor unit, and back to the compressor. Additionally, the fluid pump is activated to facilitate heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger, and the fluid pump is deactivated to stop the heat transfer from the refrigerant to the thermal energy storage fluid stored in the fluid tank via the heat exchanger, when a predetermined amount of heat has been stored in the tank.

[0010] In some embodiments, the thermal storage module is configured such that when the climate control system is in a defrost mode, both the expansion valve and the solenoid valve are opened, and the refrigerant is directed from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the heat exchanger, and back to the compressor via the solenoid valve so as to bypass the indoor unit. Additionally, the fluid pump is activated to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger, and the heat exchanger operates as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

[0011] Some embodiments disclosed herein are directed to a climate control system. The climate control system may include an indoor unit, an outdoor unit, and a refrigerant circuit for directing a refrigerant flowing between the indoor unit and the outdoor unit. The outdoor unit may include a compressor. The climate control system may further include a thermal storage device in fluid communication with the outdoor unit and the indoor unit. The thermal storage device may include a fluid pump, a fluid tank coupled to the fluid pump and storing a fluid, a heat exchanger fluidly coupled to the refrigerant circuit between an outdoor coil of the outdoor unit and an indoor coil of the indoor unit, an expansion valve coupled to the refrigerant circuit between an inlet of the heat exchanger and the outdoor unit, a solenoid valve coupled to the refrigerant circuit between an outlet of the heat exchanger and an indoor coil of the indoor unit, and a controller configured to control the fluid pump based on an operation mode of the climate control system. The fluid pump may be configured to be activated when the climate control system is operating in a heating mode or in a defrosting mode. The fluid pump may be configured to be deactivated when the climate control system is operating in a cooling mode. In some embodiments, the thermal storage module may be separate from the indoor unit and the outdoor unit and located along the refrigerant circuit therebetween.

[0012] In some embodiments of the climate control system, the fluid may be a thermal energy storage fluid or a phase-change material. In some embodiments, the expansion valve may be coupled to the outdoor unit and the indoor unit via a liquid line along the refrigerant circuit and the solenoid valve may be coupled to the outdoor unit and the indoor unit via a gas line along the refrigerant circuit. In some embodiments of the climate control system, when the climate control system is in a heating mode, the expansion valve is opened and the solenoid valve is closed, the refrigerant is directed from the compressor along the refrigerant circuit to the indoor coil of the indoor unit, the heat exchanger of the thermal storage module, the outdoor coil of the outdoor unit, and back to the compressor. Additionally, the fluid pump is activated to facilitate heat from the refrigerant to fluid stored in the fluid tank via the heat exchanger, and the fluid pump is deactivated to stop the heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger when a predetermined amount of heat is stored in the tank.

[0013] In some embodiments of the climate control system, when the climate control system is in a defrost mode, both the expansion valve and the solenoid valve are opened, and the refrigerant is directed from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the heat exchanger, and back to the compressor via the solenoid valve so as to bypass the indoor unit. Additionally, when the climate control system is in a defrost mode, the fluid pump is activated to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger, and the heat exchanger operates as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

[0014] Some embodiments disclosed herein are directed to a method of operating a defrost mode for a climate control system. In such embodiments, the climate control system may include a refrigerant circuit for directing a refrigerant flowing between an indoor unit and an outdoor unit. The outdoor unit may include a compressor. The climate control system may further include a thermal storage module located between the indoor unit and the outdoor unit. The method may include activating or deactivating the thermal storage module based on one or more mode of operation signals received from the climate control system. The method may also include directing, when the climate control system is in a defrost mode, the refrigerant from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the thermal storage module, and back to the compressor via the solenoid valve so as to bypass the indoor unit.

[0015] The thermal storage module included in the method may include a fluid pump, a fluid tank coupled to the fluid pump and storing a fluid, a heat exchanger fluidly coupled to the refrigerant circuit between an outdoor coil of the outdoor unit and an indoor coil of the indoor unit, an expansion valve coupled to the refrigerant circuit between an inlet of the heat exchanger and the outdoor unit; a solenoid valve coupled to the refrigerant circuit between an outlet of the heat exchanger and an indoor coil of the indoor unit, and a controller configured to control the fluid pump based on an operation mode of the climate control system. The expansion valve may be coupled to the outdoor unit and the indoor unit via a liquid line along the refrigerant circuit and the solenoid valve may be coupled to the outdoor unit and the indoor unit via a gas line along the refrigerant circuit.

[0016] According to certain embodiments of the method, when the climate control system is in the defrosting mode, the method may include opening both the expansion valve and the solenoid valve as well as activating the fluid pump to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger, and operating the heat exchanger as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit. In certain embodiments, the method may include installing the thermal storage module along the refrigerant circuit between the indoor unit and the outdoor unit. In such embodiments, the thermal storage module is a separate unit from the indoor unit and the outdoor unit.

[0017] According to certain embodiments of the method, when the climate control system is in a heating mode, the method may include opening the expansion valve and closing the solenoid valve, and directing the refrigerant from the compressor of the outdoor unit along the refrigerant circuit to the indoor coil of the indoor unit, to the heat exchanger of the thermal storage module, to the outdoor coil of the outdoor unit, and back to the compressor of the outdoor unit. In such embodiments, the method may also include activating the fluid pump of the thermal storage module to facilitate heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger. The method may also include deactivating the fluid pump of the thermal storage module when the climate control system is in a cooling mode. The method may also include, in some embodiments, opening the expansion valve and closing the solenoid valve; and directing the refrigerant from the compressor of the outdoor unit to the outdoor coil of the outdoor unit, the heat exchanger of the thermal storage unit, an indoor coil of the indoor unit, and back to the compressor of the outdoor unit.

[0018] 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

[0019] For a detailed description of various embodiments, reference will now be made to the accompanying drawings in which:

[0020] FIG. 1 is a schematic diagram of a heat pump operating in a heating mode according to some embodiments disclosed herein;

[0021] FIG. 2 is a schematic view of a thermal storage device of the heat pump of FIG. 1 according to some embodiments disclosed herein;

[0022] FIG. 3 is a schematic diagram of the heat pump of FIG. 1 operating in a defrost mode according to some embodiments disclosed herein;

[0023] FIG. 4 is a schematic diagram of a heat pump operating in a heating mode according to some embodiments disclosed herein;

[0024] FIG. 5 is a schematic diagram of the heat pump of FIG. 4 operating in a defrost mode according to some embodiments disclosed herein;

[0025] FIG. 6 is a schematic diagram of a heat pump operating in a heating mode according to some embodiments disclosed herein;

[0026] FIG. 7 is a schematic diagram of the heat pump of FIG. 6 operating in a defrost mode according to some embodiments disclosed herein;

[0027] FIG. 8 is a diagram of a method of operating a heat pump during a defrost mode operation according to some embodiments;

[0028] FIG. 9 is a schematic diagram of a separate thermal storage device attached between an indoor unit and an outdoor unit of a climate control system according to some embodiments;

[0029] FIG. 10 is a block diagram showing a separate thermal storage device installed between an indoor unit and an outdoor unit of a climate control system according to some embodiments;

[0030] FIG. 11A depicts a flowchart of a method of operating a climate control system in a defrost mode using a thermal storage device attached thereto;

[0031] FIG. 11 B depicts a flowchart of a method of operating a climate control system in a heating mode using a thermal storage device attached thereto; and

[0032] FIG. 11C depicts a flowchart of a method of operating a climate control system in a cooling mode using a thermal storage device attached thereto.DETAILED DESCRIPTION

[0033] A heat pump may heat an interior space by circulating a refrigerant between a first heat exchanger to transfer heat from an outdoor environment to the refrigerant and a second heat exchanger to transfer heat from the refrigerant to the interior space. The first heat exchanger may be positioned or at least exposed to the outdoor environment, and thus may be referred to herein as an “outdoor heat exchanger.” The heat transfer from the outdoor environment to the refrigerant during operation of the heat pump may cause one or more surfaces of the outdoor heat exchanger to fall below the freezing point of water. As a result, during operation of the heat pump, ice may form on the outdoor heat exchanger that may reduce the heat transfer capabilities thereof. Accordingly, a heat pump may be periodically operated in a defrost mode that is configured to transfer heat to the outdoor heat exchanger to thereby melt ice accumulated thereon.

[0034] For some heat pumps, heat is transferred to the outdoor heat exchanger during a defrost mode by use of one or more supplemental heating devices, such as electrically resistive coils. However, these supplemental heating devices may reduce the operating efficiency of the heat pump by notably increasing the amount of fuel or electrical power that is needed to operate the heat pump.

[0035] Additionally, some heat pumps may transfer heat to the outdoor heat exchanger by reversing the flow direction of the refrigerant (e.g., relative to that normally associated with a heating mode operation) so as to transfer heat to the outdoor heat exchanger from the interior space via the refrigerant itself. However, while this method of defrosting the outdoor heat exchanger may avoid the inefficiencies associated with supplemental heating device, reversing the flow direction of the refrigerant may cause the cool or cold air to be delivered to the interior space (a phenomenon often referred to as “cold blow”), thereby reducing occupant comfort.

[0036] Accordingly, embodiments disclosed herein include systems and methods for defrosting an outdoor heat exchanger of a heat pump while preserving occupant comfort and promoting improved operating efficiency. In some embodiments, the systems and methods may utilize a thermal storage device that may store thermal energy for transfer to the refrigerant during a defrost mode to both support the defrost operations and to reduce or eliminate cold blow. In addition, some embodiments may include methods for operating a heat pump that may also reduce or prevent a cool or cold airflow to the interior space during a defrost operation. Thus, by use of the embodiments disclosed herein, a heat pump may manage ice accumulation on the outdoor heat exchanger without substantially effective occupant comfort while maintaining the operating efficiency.

[0037] The heat pump, in some examples, may include a thermal storage module that is configured to add supplemental heat to a refrigerant at an advantageous position along the refrigerant circuit during a defrost mode operation to reduce or prevent cold blow into the interior space. Specifically, the heat pump may include a thermal storage module positioned along the refrigerant circuit between first expansion device and second expansion device. The thermal storage module may be in fluid communication between the first and second expansion devices along with the refrigerant circuit. In some examples, the thermal storage module is incorporated into an outdoor unit. In other examples, the thermal storage module may also be incorporated into the indoor unit or even positioned between the indoor unit and the outdoor unit.

[0038] In some examples, the thermal storage module may be a separate unit and is installable along a refrigerant circuit between the indoor unit and the outdoor unit of a climate control system, e.g., a heat pump or a HVAC, when needed. The climate control system comprises the refrigerant circuit for directing a refrigerant flowing between the indoor unit and the outdoor unit. The outdoor unit comprises a compressor. The thermal storage module may be connected to the indoor unit and the outdoor unit via a gas line and a liquid line and is activated when the climate control system is operating in a heating mode and a defrost mode but is deactivated when the climate control system is operating in a cooling mode. The thermal storage module may comprise a fluid tank containing a thermal energy storage fluid which may be a phase change material, and a fluid pump configured to circulate a working fluid through the fluid tank, in which the working fluid exchanging thermal energy with the thermal energy storage fluid. The thermal storage module may further comprise a heat exchanger that is configured to exchange thermal energy between the working fluid and a refrigerant flow within the refrigerant circuit. An expansion valve may be coupled to the refrigerant circuit between the heat exchanger of the thermal storage module and the outdoor unit. Further, a solenoid valve may be coupled to the refrigerant circuit between the heat exchanger of the thermal storage module and to the indoor unit. The solenoid is configured to provide a bypass path for the refrigerant flowing from the compressor to the thermal storage module and back to the outdoor unit, bypassing the indoor unit, during a defrost mode.

[0039] In the case that the thermal storage module is a separate device from the climate control system, the thermal storage module may comprise a controller that is communicable with a system controller to control the fluid pump, the expansion valve, and the solenoid valve based on an operation mode of the climate control system. When the climate control system is operating in a heating mode, the expansion valve is opened and the solenoid valve is closed, which allows the refrigerant flowing from the compressor to be directed to an indoor coil of the indoor unit, the heat exchanger of the thermal storage module, the outdoor coil of the outdoor unit, and back to the compressor. At the same time, the fluid pump is activated to facilitate heat transfer from the refrigerant to the thermal storage fluid stored in the fluid tank via the heat exchanger until a desired amount of heat has been stored in the fluid tank of the thermal storage module.

[0040] Moreover, when the climate control system is operating in a defrost mode, the expansion valve and the solenoid valve are both opened so that the refrigerant is directed from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the heat exchanger of the thermal storage module, and back to the compressor via the solenoid valve so as to bypass the indoor unit. The fluid pump is activated to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger of the thermal storage module. In this example, the heat exchanger of the thermal storage module operates as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

[0041] In some examples, the thermal storage fluid stored in the fluid tank of the thermal storage module may be a phase change material that is configured to transition between a first state of matter and a second state of matter when receiving or expelling heat during operations. In some embodiments, the phase change material in the thermal storage module may be configured to transition to a liquid state and to a solid state during operations. Specifically, the phase change material may generally have a relatively high heat of fusion, which may refer to the heat absorbed by the substance as the phase change material transitions from a solid to a liquid. Likewise, the phase change material may also have a relatively high heat of solidification, which may refer to the heat emitted from the phase change material as it transitions from a liquid state to a solid state. Thus, the phase change material may be configured so as to absorb and store heat when exposed to substances or environments having an energy greater than the heat of fusion of the phase change material and may be configured to release or emit heat to substances or environments having an energy below the heat of fusion of the phase change material. For instance, the refrigerant may be flowed through the thermal storage module until the thermal storage medium stored therein reaches a desired temperature. For embodiments of thermal storage module that employ a phase change material as the thermal storage fluid, when a temperature of the phase change material stored in the thermal storage module is greater than the phase change temperature thereof, this may indicate that all (or substantially all) of the phase change material has transitioned from a solid state to a liquid state. From this point on, additional heat absorption by the phase change material in the thermal storage module may be significantly reduced.

[0042] Referring now to FIG. 1, a heat pump 10 for heating an interior space 12 is shown according to some embodiments disclosed herein. In some embodiments, the interior space 12 may be 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 heated 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.

[0043] The heat pump 10 may be configured to circulate a refrigerant through a fluid circuit (or refrigerant circuit) 58 to transfer heat between the interior space 12 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 some embodiments, the interior space 12 is an interior space of a house as previously described, and the outdoor environment comprises the outdoor environment that surrounds the house.

[0044] The heat pump 10 may include a compressor 30, a first heat exchanger 32, a pair of expansion devices 36, 42, a second heat exchanger 44, and a reversing valve 28 that are interconnected by a plurality of refrigerant lines 56 to at least partially define the fluid circuit 58. The fluid circuit 58 may circulate any suitable refrigerant (or refrigerants) during operations. For instance, in some embodiments, the fluid circuit 58 may circulate one or more refrigerants that may comprise hydrofluorocarbons (HFCs), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), fluorocarbons (FCs), hydrocarbons (HCs), Ammonia (NH3), carbon dioxide (CO2), or some combination thereof.

[0045] Valving of the heat pump 10 (e.g., reversing valve 28, valves 94, 96 described herein, expansion devices 36, 42, etc.) may be actuatable to selectively operate the heat pump 10 in various modes of operation, such as a heating mode, a cooling mode, and a defrost mode of operation. For instance, during the cooling mode operation, the heat pump 10 may generally transfer heat from the interior space 12 to the outdoor environment 5 via the fluid circuit 58, and during the heating mode operation, the heat pump 10 may generally transfer heat from the outdoor environment 5 to the interior space 12 via the fluid circuit 58. FIG. 1 specifically depicts the heat pump 10 operating in a heating mode.

[0046] Specifically, as shown in FIG. 1, during a heating mode operation to heat the interior space 12, the compressor 30 compresses the refrigerant in a gaseous state and outputs the compressed refrigerant to the reversing valve 28, which may be in a first position so as to route the compressed refrigerant to the second heat exchanger 44. In the heating mode operation of FIG. 1, the second heat exchanger 44 is configured to facilitate heat transfer from the refrigerant to the interior space 12. Specifically, the refrigerant may flow through one or more coils of the second heat exchanger 44, while a blower 48 generates an airflow 50 that is flowed over and around the second heat exchanger 44 to thereby draw heat away from the refrigerant flowing therein. The airflow 50 is then directed away from the second heat exchanger 44 and into the interior space 12 via suitable ducting 52 (e.g., rigid ducts, flexible hoses, or any other suitable fluid conveyance system). The transfer of heat from the airflow 50 to the refrigerant via the second heat exchanger 44 may cause the refrigerant to at least partially condense to a liquid, such that the second heat exchanger 44 may function as a “condenser” when operating in the heating mode of FIG. 1.

[0047] The liquid (or substantially liquid) refrigerant is then directed through the second expansion device 42. In the heating mode operation of FIG. 1, the second expansion device 42 may be positioned or actuated as to not substantially restrict or meter the flow of refrigerant therethrough. Alternatively, in the heating mode of FIG. 1, the refrigerant may be bypassed around the second expansion device 42 so that the second expansion device 42 may not restrict refrigerant as previously described. After progressing past the second expansion device 42, the refrigerant may by directed through the first expansion device 36 which may be actuated or set so as to controllably constrict and expand the flow of refrigerant so as to reduce a temperature thereof.

[0048] The first expansion device 36 and second expansion device 42 may comprise orifices or expansion valves, such as electronic expansion valves (EEVs) that are actuated by a controller (e.g., controller 80 described herein). Alternatively, the first expansion device 36 and the second expansion device 42 may comprise a thermostatic expansion valve (TXV) that is 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 58 (or a portion thereof).

[0049] The expanded, cold refrigerant emitted from the first expansion device 36 is then directed through the first heat exchanger 32 which is configured to transfer heat from an airflow 40 generated by a fan 38 to the refrigerant. Specifically, the refrigerant may flow through one or more coils of the first heat exchanger 32, while the fan 38 generates the airflow 40 that is flowed over and around the first heat exchanger 32 to thereby draw heat away from the airflow 40 and into the refrigerant. The cooled airflow 40 is then discharged from the first heat exchanger 32 to the outdoor environment 5.

[0050] The transfer of heat from the airflow 40 to the refrigerant via the first heat exchanger 32 may cause the refrigerant to vaporize or at least partially vaporize to a gas, such that the first heat exchanger 32 may function as an “evaporator” when operating in the heating mode of FIG. 1. The vaporized (or partially vaporized) refrigerant may progress from the first heat exchanger 32 back to the compressor 30 via the reversing valve 28 so as to restart the cycle described above.

[0051] Generally speaking, during a cooling mode operation of the heat pump 10 the flow direction of the refrigerant in the fluid circuit 58 is reversed from that described for the heating mode operation (FIG. 1). Thus, during a cooling mode operation, the reversing valve 28 is actuated from the first position of FIG. 1 to a second position so as to route the compressed refrigerant emitted from the compressor 30 to the first heat exchanger 32 rather than the second heat exchanger 44. As a result, in the cooling mode operation, the first heat exchanger 32 is configured to transfer heat from the refrigerant to the outdoor environment 5 via airflow 40 so as to condense the refrigerant. As a result, the first heat exchanger 32 functions as a “condenser” for the refrigerant during the cooling mode. The condensed refrigerant is then directed through the first expansion device 36 and the second expansion device 42; however, in the cooling mode operation, the first expansion device 36 is either positioned or actuated so as to not substantially restrict or meter the flow of refrigerant therethrough, or the refrigerant is bypassed around the first expansion device 36. However, in the cooling mode, the second expansion device 42 is actuated so as to controllably constrict and expand the flow of refrigerant so as to reduce a temperature thereof.

[0052] The expanded, cold refrigerant is then directed through the second heat exchanger 44 which is configured to transfer heat from the airflow 50 to the refrigerant to thereby vaporize the refrigerant and cool the airflow 50 (which is then directed to the interior space via the ducting 52). Thus, in the cooling mode operation, the second heat exchanger 44 functions the “evaporator” for the refrigerant. Finally, the vaporized refrigerant is routed back to the compressor 30 via the reversing valve 28 to restart the cycle described above.

[0053] Referring still to FIG. 1, in some embodiments, the second heat exchanger 44, second expansion device 42, and blower 48 may be embodied as an at least partially integrated first unit 60. In addition, in some embodiments, the first heat exchanger 32, first expansion device 36, fan 38, fan motor 39, reversing valve 28, and compressor 30 may be embodied as an at least partially integrated second unit 70. In some embodiments, the first unit 60 may be positioned in any suitable indoor space that may or may not be the same (or connected to) the interior space 12. For instance, the first unit 60 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. Likewise, the second unit 70 may be positioned in the outdoor environment 5. Thus, in some embodiments, the first unit 60 may be referred to herein as an “indoor unit” and the second unit 70 may be referred to as an “outdoor unit.”

[0054] Accordingly, the first heat exchanger 32 may be referred to herein as an “outdoor heat exchanger,” the second heat exchanger 44 may be referred to herein as an “indoor heat exchanger,” the first expansion device 36 may be referred to herein as an “outdoor expansion device,” and the second expansion device 42 may be referred to herein as an “indoor expansion device.”

[0055] However, these example positions of the units 60, 70 are not intended to limit a particular location of either of the units 60, 70 in various embodiments. For example, in some embodiments, the first unit 60 and second unit 70 may be at least partially integrated with one another and co-located in single location. For instance, in some embodiments, the first unit 60 and the second unit 70 may be integrated with one another as a so-called “packaged unit” and located in the outdoor environment 5. In some embodiments, the at least partially integrated units 60, 70 (e.g., as a packaged unit) may be positioned on a rooftop of the house 14, dwelling, building, etc. that defines the interior space 12.

[0056] When the heat pump 10 is operating in the heating mode of FIG. 1, the cold refrigerant flowing through the outdoor heat exchanger 32 may cause one or more surfaces of the first heat exchanger 32 to accumulate ice. For instance, ice formation on the outdoor heat exchanger 32 may occur when heat pump 10 is operating in a colder climate. The formation of ice on the outdoor heat exchanger 32 may prevent or substantially reduce the heat transfer functionality thereof by at least partially obstructing the airflow 40 therethrough and insulating the air from the refrigerant. Thus, the heat pump 10 may be selectively operated in a defrost mode to transfer heat to the outdoor heat exchanger 32 via the refrigerant so as to remove or reduce accumulated ice.

[0057] Generally speaking, a defrost mode for the heat pump 10 may include reversing the flow of refrigerant along the refrigerant circuit 58 in a similar manner to that described above for the cooling mode previously described. Conventionally, during a defrost mode operation, heat may be transferred to the refrigerant from the interior space 12 in the indoor heat exchanger 44 (e.g., via the airflow 50) and then is transferred from the refrigerant to the outdoor heat exchanger 32. However, this operation may reduce the temperature of airflow 50 and therefore result so-called “cold blow” to the interior space 12, thereby substantially reducing occupant comfort.

[0058] Thus, the heat pump 10 illustrated in FIG. 1 may include a thermal storage device 100 that is configured to add supplemental heat to the refrigerant at an advantageous position along the refrigerant circuit 58 during a defrost mode operation so as to reduce or prevent cold blow into the interior space 12. Specifically, as shown in FIG. 1, the heat pump 10 includes a thermal storage device 100 that is positioned along the refrigerant circuit 58 between the first expansion device 36 and the second expansion device 42. Thus, the thermal storage device 100 may be in fluid communication between the expansion devices 36, 42 along the refrigerant circuit 58. In the embodiment illustrated in FIG. 1, the thermal storage device 100 is incorporated into the outdoor unit 70; however, it should be appreciated that the thermal storage device 100 may be incorporated into the indoor unit 60 or even positioned between the units 60, 70.

[0059] The thermal storage device 100 may include at least one thermal storage medium that is configured to receive and store thermal energy during operations. Thus, the thermal storage device 100 may comprise a heat exchanger that is configured to transfer heat between the thermal storage medium of the thermal storage device 100 and the refrigerant flowing along the refrigerant circuit 58 (specifically the refrigerant flowing between the expansion devices 36, 42 along refrigerant circuit 58). In some embodiments the thermal storage medium in the thermal storage device 100 may comprise an aqueous fluid, such as water or a water-glycol mixture.

[0060] In some embodiments, the thermal storage medium of the thermal storage device 100 may comprise a phase change material that is configured to transition between a first state of matter and a second state of matter when receiving or expelling heat during operations. In some embodiments, the phase change material in the thermal storage device 100 may be configured to transition to a liquid state and to a solid state when receiving heat from and emitting heat to, respectively, the refrigerant flowing between the expansion devices 36, 42 during operations. Specifically, the phase change material may generally have a relatively high heat of fusion, which may refer to the heat absorbed by the substance as the phase change material transitions from a solid to a liquid. Likewise, the phase change material may also have a relatively high heat of solidification, which may refer to the heat emitted from the phase change material as it transitions from a liquid state to a solid state. Thus, the phase change material may be configured so as to absorb and store heat when exposed to substances or environments having an energy greater than the heat of fusion of the phase change material, and may be configured to release or emit heat to substances or environments having an energy below the heat of fusion of the phase change material.

[0061] The phase change material of the thermal storage device 100 may comprise any suitable material that is configured to change phase to absorb and emit heat at the operating temperatures of the refrigerant of heat pump 10 during the defrost operation. For example, in some embodiments, the phase change material may comprise one or more paraffins, fatty acids, hydrates, molten salt, metal alloy, etc.

[0062] The thermal storage device 100 may have any suitable design for thermally contacting the phase change material (or other thermal storage medium) with the refrigerant during operations. For instance, thermal storage device 100 may comprise a brazed plate heat exchange similar to those described in U.S. Pat. No. 11,959,690, the contents of which are incorporated herein by reference. Alternatively, as shown in FIG. 2, in some embodiments, the thermal storage device 100 may comprise a tank or reservoir 102 holding a volume of the phase change material 104 (or other thermal storage medium as previously described) and a coil or tube 106 that is configured to receive and direct refrigerant therethrough. The coil 106 may be routed through the reservoir 102 so that as refrigerant flows through the coil 106 heat is exchanged between the refrigerant and the phase change material 104 via the wall of the coil 106. The coil 106 may include or be coupled to one or more heat transfer features such as fins, plates, etc. (not shown) that are configured to enhance heat transfer between the refrigerant and the phase change material 104 during operations. Thus, as the refrigerant flows through the thermal storage device 100, the refrigerant may be prevented from physically contacting and mixing with the phase change material 104 but may be allowed to freely exchange heat with the phase change material 104 through at least the walls of coil 106.

[0063] Referring again to FIG. 1, during the heating mode operation with heat pump 10, refrigerant that is emitted from the indoor heat exchanger 44 may be flowed through the opened indoor expansion device 42 or bypassed around the indoor expansion device 42 such that the refrigerant is not restricted or metered as previously described. The refrigerant may then flow through the thermal storage device 100. Specifically, a bypass valve 94 positioned along the refrigerant line 56 between the expansion devices 36, 42 may be closed so as to route the refrigerant through the thermal storage device 100 via lines 99 and 98. The portion 56a of the refrigerant line 56 extending between the lines 98, 98 may define a bypass line for selectively bypassing refrigerant around the thermal storage device 100 during operations.

[0064] A valve 96 positioned along the line 98 may be opened to allow the refrigerant discharged from the thermal storage device 100 to re-enter the refrigerant line 56 extending between the expansion devices 36, 42 and then progress onward to the outdoor expansion device 36. The outdoor expansion device 36 may expand the refrigerant so that the refrigerant may then receive heat from the airflow 40 via the outdoor heat exchanger 32 as previously described.

[0065] During these operations, the refrigerant downstream of the indoor heat exchanger 44 is generally cooled via contact with the airflow 50. However, there is still enough residual heat in the refrigerant so that as the refrigerant flows through the thermal storage device 100 heat may be transferred from the refrigerant to the thermal storage medium of the thermal storage device 100. In particular, for embodiments of the thermal storage device 100 that include a phase change material as the thermal storage medium (e.g., phase change material 104 in FIG. 2), the heat transferred from the refrigerant into the phase change material may be sufficient to at least partially transition the phase change material from a solid state to a liquid state. Stated differently, the refrigerant flowing downstream of the indoor heat exchanger 44 during the heating mode operation of heat pump 10 (FIG. 1) may be heated above the heat of fusion of the phase change material in the thermal storage device 100.

[0066] The refrigerant may continue to be routed through the thermal storage device 100 during the heating mode operation of the heat pump 10 (FIG. 1) until a desired amount of heat has been stored in the thermal storage device 100. For instance, the refrigerant may be flowed through the thermal storage device 100 until the thermal storage medium stored therein reaches a desired temperature. For embodiments of thermal storage device 100 that employ a phase change material as the thermal storage medium as previously described, when a temperature of the phase change material stored in the thermal storage device 100 is greater than the phase change temperature thereof, this may indicate that all (or substantially all) of the phase change material has transitioned from a solid state to a liquid state. From this point on, additional heat absorption by the phase change material in the thermal storage device 100 may be significantly reduced, and it may be desirable to maintain a higher amount of heat in the refrigerant flowing to the outdoor expansion device 36 and outdoor heat exchanger 32 to promote efficient operation of heat pump 10.

[0067] Thus, once the phase change material of thermal storage device 100 reaches a desired temperature, the bypass valve 94 may be closed and the valve 96 positioned along line 98 may be opened so as to allow refrigerant flowing out of the indoor heat exchanger 44 and indoor expansion device 42 to bypass the thermal storage device 100 and proceed directly to the outdoor expansion device 36. The thermal storage device 100 may include insulation that may allow the phase change material (e.g., phase change material 104 in FIG. 2) to retain heat absorbed therein.

[0068] A temperature sensor 92 may be used to determine when and whether to flow warm refrigerant through the thermal storage device 100 during the heating mode operation of heat pump 10. For instance, the temperature sensor 92 may be coupled to the thermal storage device 100 that is configured to measure a temperature of the thermal storage device 100, such as a temperature of the phase change material itself. The temperature sensor 92 may comprise any suitable sensor or sensor array that is configured to measure or detect a temperature or a value indicative thereof. In some embodiments, the temperature sensor 92 may comprise a thermocouple, a thermistor, a resistive temperature sensor, a semi-conductor temperature sensor, an infrared temperature sensor, or some combination thereof.

[0069] During operations, an output of the temperature sensor 92 may be monitored (e.g., by the controller 80 as described in more detail herein) to determine whether refrigerant should be routed through the thermal storage device 100 as part of the heating mode operation for heat pump 10 (FIG. 1). For instance, when the output from the temperature sensor 92 indicates that a temperature of the phase change material is below a first threshold (which may be less than the phase change temperature of the phase change material), the valves 94, 96 may be actuated to route the refrigerant through the thermal storage device 100 to transfer heat form the refrigerant of the phase change material as previously described. Conversely, when the output from the temperature sensor 92 indicates that the temperature of the phase change material is above a second threshold (which may be greater than the phase change temperature of the phase change material), the valves 94, 96 again may be actuated to bypass the refrigerant around the thermal storage device 100 (e.g., via the bypass portion 56a of the refrigerant line 56 extending between the expansion devices 36, 42 in FIGS. 1 and 3).

[0070] In some embodiments, the refrigerant is not bypassed around the thermal storage device 100, and refrigerant is continuously flowed through the thermal storage device 100 during the heating mode operation of heat pump 10 (FIG. 1). During this operation, the heat continues to transfer to the thermal storage medium (e.g., phase change material 104 in FIG. 2) of the thermal storage device (100) until the temperature of the thermal storage medium matches that of the refrigerant. Thereafter, the continued flowing of refrigerant through the thermal storage device 100 as part of the heating mode operation may maintain the temperature of the thermal storage medium of the thermal storage device 100 at the temperature of the refrigerant.

[0071] Referring now to FIG. 3, when it becomes desirable to defrost the first outdoor exchanger 32, the reversing valve 28 may be actuated to the second position to direct the warm vaporized refrigerant discharged from the compressor 30 to the outdoor heat exchanger 32 in the same manner as during a cooling mode operation with heat pump 10. The flow of the warm refrigerant through the outdoor heat exchanger 32 may transfer heat from the refrigerant to the ice built upon on the heat exchanger 32 to thereby melt ice. In addition, the transfer of heat from the refrigerant in the first heat exchanger 32 may also cool and condense the refrigerant.

[0072] The cooled liquid (or substantially liquid) refrigerant is then flowed through the opened outdoor expansion device 36 or bypassed around the outdoor expansion device 36 so that the refrigerant is not restricted or metered as previously described. In addition, the bypass valve 94 may be closed and the valve 96 may be opened so that the refrigerant downstream of the outdoor expansion device 36 is directed through the thermal storage device 100.

[0073] As previously described, during the previous heating mode operation (FIG. 1), heat was transferred to the thermal storage device 100 so that the thermal storage medium stored in the thermal storage device 100 is at an elevated temperature. For embodiments of thermal storage device 100 that use a phase change material as the thermal storage medium (e.g., phase change material 104 in FIG. 2), at the initiation of the defrost operation of FIG. 3 the phase change material stored in the thermal storage device 100 may be in a substantially liquid state.

[0074] During the defrost operation shown in FIG. 3, as the cooled refrigerant is directed through the thermal storage device 100 (albeit in the reverse direction from that described during the heating mode operation in FIG. 1), heat stored in the thermal storage device 100 may be transferred to the refrigerant so as to cool the thermal storage medium in the thermal storage device 100. For embodiments of the thermal storage device 100 that utilize a phase change material (e.g., phase change material 104 in FIG. 2) as the thermal storage medium, the flow of cool refrigerant through the thermal storage device 100 during the defrost mode operation may lower the temperature of the phase change material such that it begins to at least partially transition back from a liquid state to a solid state. Thus, in some embodiments, the refrigerant downstream of the outdoor expansion device 36 during a defrost mode operation of heat pump 10 (FIG. 3) may be at a temperature that is below the heat of solidification of the phase change material contained in the thermal storage device 100.

[0075] The heated refrigerant emitted from the thermal storage device 100 is then progressed to the indoor expansion device 42 which selectively expands the refrigerant into a vapor state (or partial vapor state). The vapor (or partially vapor) refrigerant is then flowed through the indoor heat exchanger 44. In some embodiments, the airflow 50 may be reduced or even stopped during the defrost mode operation so as to prevent or reduce heat transfer from the airflow 50 to the refrigerant (and therefore prevent or reduce cold blow to the interior space 12) as the refrigerant progresses through and out of the indoor heat exchanger 44. In some embodiments, residual heat that is stored in the indoor heat exchanger 44 may further heat the refrigerant as it flows therethrough. The still warm and vapor (or substantially vapor) refrigerant discharged from the indoor heat exchanger 44 and is then directed back to the compressor 30 via the reversing valve 28 so as to restart the cycle described above.

[0076] The heat pump 10 may continue to operate in the defrost mode illustrated in FIG. 3 until the ice (or at least a desired portion thereof) accumulated on the outdoor heat exchanger 32 is removed. In some embodiments, a temperature sensor 91 on or adjacent to the outdoor heat exchanger 32 may be used to determine when the defrosting operation should be terminated. For instance, if the temperature sensor 91 detects a temperature above a threshold, it may indicate that all (or a desirable portion) of the ice accumulated on the first heat exchanger has been removed. In some embodiments, the pressure or temperature of the refrigerant emitted from the first heat exchanger 32 (or elsewhere along the refrigerant circuit 58) may provide an indication that the ice accumulated onto the first heat exchanger 32 has been removed (or sufficiently removed).

[0077] In some embodiments, the defrost operation shown in FIG. 3 may continue until all or substantially all of the available heat is transferred out of the thermal storage device 100 to the refrigerant. For instance, the temperature sensor 92 may monitor the temperature of the thermal storage device 100 (or the thermal storage medium stored therein) to determine when a temperature of the thermal storage medium has fallen below a threshold that would indicate that further heat transfer from the thermal storage device 100 to the refrigerant is no longer possible. At this point, the defrost operation of FIG. 3 may be ceased and the heat pump 10 may resume a heating mode operation as depicted in FIG. 1 and previously described.

[0078] Thus, during the defrost operation of FIG. 3, heat for defrosting the first heat exchanger 32 may largely be derived from the thermal storage device 100 rather than from the heat of the interior space 12 via the airflow 50. Accordingly, the thermal storage device 100 may prevent or reduce cold blow in the interior space 12 so that occupant comfort may be preserved.

[0079] Without being limited to this or any other theory, positioning of the thermal storage device 100 between the expansion devices 36, 42 along the refrigerant circuit 58 may help to maintain efficient operation of the heat pump 10 during operations. Specifically, if the thermal storage device 100 were positioned between the indoor expansion device 42 and the indoor heat exchanger 44, the thermal storage device 100 could induce turbulence in the flow of expanded refrigerant emitted from the second expansion device 42 during a cooling mode operation. Such turbulence could result in an uneven flow distribution through the indoor heat exchanger 44 and therefore negatively impact its operating efficiency and heat transfer functionality.

[0080] Referring now to FIGS. 4 and 5, a heat pump 110 for heating the interior space 12 is shown according to some embodiments disclosed herein. The heat pump 110 may be generally the same as the heat pump 10 shown in FIGS. 1 and 3. Thus, the same reference numerals are used in FIGS. 4 and 5 to indicate the features of heat pump 110 that are shared with the heat pump 10. Moreover, the following description will focus on features of heat pump 110 that are different from the heat pump 10.

[0081] Specifically, the heat pump 110 may include an additional bypass line 112 that extends from the refrigerant line 56, between the thermal storage device 100 and the second expansion device 42, to the refrigerant line 56 extending between the indoor heat exchanger 44 and the reversing valve 28. A first bypass valve 114 is positioned along the bypass line 112, and a second bypass valve 116 is positioned along the refrigerant line 56, between the bypass line 112 and the second expansion device 42.

[0082] In addition, the heat pump 110 may include a third expansion device 120 that is positioned along a line 122 that is coupled between the first expansion device 36 and thermal storage device 100 in parallel with the valve 96. The third expansion device 120 may be the same or similar to the expansion devices 36, 42. Thus, the description of the expansion devices 36, 42 may be applied to describe the third expansion valve 120.

[0083] Referring specifically to FIG. 4, the heating mode operation of the heat pump 110 may be substantially the same as that described above for the heat pump 10 (FIG. 1). Thus, during the heating mode operation of FIG. 4, valving of the heat pump 110 (e.g., reversing valve 28, valves 94, 96, 114, 116, expansion devices 36, 42, 120, etc.) may be actuated such that the refrigerant may be flowed through the thermal storage device 100 to transfer heat to a thermal storage medium stored therein (e.g., phase change material 104 shown in FIG. 2). During this process, the bypass valve 114 may be closed and the valve 116 may be opened so that refrigerant flowing downstream of the second expansion device 42 is not flowed through bypass line 112 and is directed to the thermal storage device 100 as previously described. In addition, the refrigerant emitted from the thermal storage device 100 may flow to the first expansion device 36 via the line 98 and open valve 96 and therefore is bypassed around the bypass line 122 and third expansion valve 120.

[0084] Therefore, in the same manner described above for the heat pump 10, operation of the heat pump 110 in the heating mode (FIG. 4) may allow thermal storage device 100 to receive heat from the refrigerant flowing along the refrigerant circuit 58 between the expansion devices 36, 42. The flow of refrigerant through the thermal storage device 100 of heat pump 110 may be continuous or selective during the heating mode operation as previously described above for the heat pump 10.

[0085] Referring now to FIG. 5, during the defrost mode for heat pump 110, the valving of the heat pump 110 may be actuated to reverse the flow direction of refrigerant along refrigerant circuit 58 as previously described. In addition, the refrigerant downstream of the first expansion device 36 may progress through the third expansion device 120. Specifically, the valves 94, 96 may be closed so that the refrigerant downstream of the first expansion device 36 may flow along the bypass line 122 and through the third expansion device 120 enroute to the thermal storage device 100. The third expansion device 120 may expand the refrigerant into a mixed phase state (including a mixture of both vapor and liquid). The expanded refrigerant may then be flowed into the thermal storage device 100 where it is heated via the thermal storage medium as previously described. The heat transferred to the refrigerant in the thermal storage device 100 may further vaporize the refrigerant so that the refrigerant emitted from the thermal storage device 100 may comprise (or substantially comprise) a vapor. Because the third expansion device 120 is configured to expand refrigerant flowing into the thermal storage device 100 during a defrost mode operation, the third expansion device 120 may be referred to herein as a “defrost expansion device.”

[0086] In addition, during the defrost mode of FIG. 5, the valve 116 may be closed and the valve 114 may be opened. As a result, the heated and vaporized refrigerant is then flowed along the bypass line 112 back to the compressor 30 via the reversing valve 28 to restart the cycle described above.

[0087] Thus, during the defrost operation of FIG. 5 and as also previously described for the heat pump 10, heat for defrosting the outdoor heat exchanger 32 may largely be derived from the thermal storage device 100 rather than from the heat of the interior space 12 via the airflow 50. Accordingly, the thermal storage device 100 may prevent or reduce cold blow in the interior space 12 so that occupant comfort may be preserved.

[0088] In addition, during the defrost operation of heat pump 110, the refrigerant is entirely bypassed around the indoor unit 60, and therefore is specifically bypassed around the indoor heat exchanger 44 and the indoor expansion device 42. Without being limited to this or any other theory, bypassing the indoor unit 60 may prevent any heat transfer to or from the interior space 12 via the refrigerant, which may prevent or reduce cold blow to the interior space 12 during operations. In addition, again without being limited to this or any other theory, bypassing the indoor unit 60 as described for the heat pump 110, may significantly shorten the flow path for heated refrigerant emitted from the thermal storage device 100 back to the outdoor heat exchanger. As a result, heat loss from the refrigerant after it is discharged from the thermal storage device 100 may be minimized so that more heat is delivered to the outdoor heat exchanger 32 during defrost operations.

[0089] Further, the defrost expansion device 120 may ensure that the refrigerant flowing back to the compressor 30 may be in a substantially vapor state, given that flowing a liquid refrigerant to the compressor 30 may result in damage. In addition, positioning the defrost expansion valve 120 upstream of the thermal storage device 100 may be configured to flow at least partially vaporized refrigerant through the thermal storage device 100 to thereby facilitate a more efficient sensible heat transfer to the refrigerant therein.

[0090] Referring now to FIGS. 6 and 7, a heat pump 210 for heating the interior space 12 is shown according to some embodiments disclosed herein. The heat pump 210 may be generally the same as the heat pump 10 shown in FIGS. 1 and 3. Thus, the same reference numerals are used in FIGS. 6 and 7 to indicate the features of heat pump 210 that are shared with the heat pump 10. Moreover, the following description will focus on features of heat pump 210 that are different from the heat pump 10.

[0091] For instance, the heat pump 210 may include the thermal storage device 100; however, the thermal storage device 100 may be positioned and incorporated into the indoor unit 60 rather than the outdoor unit 70. In addition, the thermal storage device 100 of heat pump 210 may be positioned along a bypass line 204 that bypasses the indoor heat exchanger 44. Specifically, the bypass line 204 extends from the refrigerant line 56 extending between the second expansion device 42 and the indoor heat exchanger 44 to the refrigerant line extending between the indoor heat exchanger 44 and the reversing valve 28.

[0092] A first bypass valve 206 may be positioned along the bypass line 204 between the thermal storage device 100 and the refrigerant line 56 extending between the indoor heat exchanger 44 and the reversing valve 28. In addition, a second bypass valve 202 may be positioned along the refrigerant line 56 extending between the indoor heat exchanger 44 and the reversing valve 28 at a point between the indoor heat exchanger 44 and the bypass line 204.

[0093] Referring specifically to FIG. 6, during the heating mode operation of the heat pump 210, valving of the heat pump 210 (e.g., reversing valve 28, valves 202, 206, expansion devices 36, 42, etc.) may be actuated such that vaporous refrigerant may be emitted from the compressor 30 and then flowed to the indoor unit 60 via the reversing valve 28 as previously described. Within the indoor unit, the refrigerant may be flowed in parallel to both the indoor heat exchanger 44 and the thermal storage device 100 so that the refrigerant transfers heat to both the airflow 50 via indoor heat exchanger 44 and to the thermal storage medium (e.g., phase change material 104 in FIG. 2) in the thermal storage device 100 simultaneously. Thus, during the heating mode of heat pump 210 (FIG. 6), both of the bypass valves 202, 206 may be open to facilitate parallel flow through both the indoor heat exchanger 44 and thermal storage device 100.

[0094] As previously described for heat pump 10, if it becomes desirable to stop flowing refrigerant through the thermal storage device 100 during the heating mode of FIG. 6, the first bypass valve 206 may be closed so that all refrigerant flowing to the indoor unit 60 from the compressor 30 may be flowed through the indoor heat exchanger 44 to improve the operating efficiency of the heat pump 210. However, as is also previously described for heat pump 10, the refrigerant may flow continuously through both the indoor heat exchanger 44 and thermal storage device 100 anytime the heat pump 210 is operating in the heating mode according to some embodiments.

[0095] Referring now to FIG. 7, during the defrost mode for heat pump 210, the valving of the heat pump 210 may be actuated to reverse the flow direction of refrigerant along refrigerant circuit 58 as previously described. In addition, the second bypass valve 202 is closed so that fluid flow may not progress through the indoor heat exchanger 44 (e.g., so that the indoor heat exchanger 44 is “dead-headed”). As a result, as refrigerant advances through and is expanded by the indoor expansion device 42 it is then routed through the thermal storage device 100 via the bypass line 204. The indoor expansion device 42 may be configured to partially expand the refrigerant so that it forms a mixed phase flow through the thermal storage device 100 to thereby promote more efficient sensible heat transfer as previously described. In addition, as the refrigerant flows through the thermal storage device 100, it may receive heat from the thermal storage medium contained therein (e.g., phase change material 104 in FIG. 2) as previously described and may transition to a fully vapor (or substantially vapor) state. The heated and vaporized refrigerant may then progress back to the compressor 30 via the reversing valve 28 to restart the cycle described above.

[0096] Thus, during the defrost operation of FIG. 7 and as also previously described for the heat pump 10, heat for defrosting the outdoor heat exchanger 32 may largely be derived from the thermal storage device 100 rather than from the heat of the interior space 12 via the airflow 50. Accordingly, the thermal storage device 100 may prevent or reduce cold blow in the interior space 12 so that occupant comfort may be preserved.

[0097] In addition, as was previously described for the heat pump 110 (FIGS. 4 and 5), during the defrost operation with the heat pump 210 the refrigerant is entirely bypassed around the indoor heat exchanger 44. As a result, heat loss from the refrigerant and the risk of lowering the temperature of airflow 50 to produce cold blow may be reduced.

[0098] Referring again to FIG. 1, the heat pump 10 may also include a controller 80 that is configured to control one or more devices or components of the heat pump 10 during operations. The heat pumps 110, 210 may also include a similar controller 80 (FIGS. 4-7), and thus the following description of the controller 80 in the heat pump 10 of FIG. 1 may be applied to describe the similar controller 80 in the heat pumps 110, 210.

[0099] The controller 80 may be (or may be incorporated within) a main or master controller for the heat pump 10, or the controller 80 may be a standalone controller 80 for controlling particular aspects or components of the heat pump 10. Regardless, the controller 80 may be described and referred to herein as being a part of the heat pump 10.

[0100] The controller 80 may comprise one or more computing devices, such as a computer, tablet, smartphone, server, circuit board, or other computing device(s) or system(s). Thus, controller 80 may include a processor 82 and a memory 84.

[0101] The processor 82 may include any suitable processing device or a collection of processing devices. In some embodiments, the processor 82 may include a microcontroller, central processing unit (CPU), graphics processing unit (GPU), timing controller (TCON), scaler unit, or some combination thereof. During operations, the processor 82 executes machine-readable instructions (such as machine-readable instructions 86) stored on memory 84, thereby causing the processor 82 to perform some or all of the actions attributed herein to the controller 80. In general, processor 82 fetches, decodes, and executes instructions (e.g., machine-readable instructions 86). In addition, processor 82 may also perform other actions, such as, making determinations, detecting conditions or values, etc., and communicating signals. If processor 82 assists another component in performing a function, then processor 82 may be said to cause the component to perform the function.

[0102] The memory 84 may be any suitable device or collection of devices for storing digital information including data and machine-readable instructions (such as machine-readable instructions 86). For instance, the memory 84 may include volatile storage (such as random-access memory (RAM)), non-volatile storage (e.g., flash storage, read-only memory (ROM), etc.), or combinations of both volatile and non-volatile storage. Data read or written by the processor 82 when executing machine-readable instructions 86 can also be stored on memory 84. Memory 84 may comprise or include a “non-transitory machine-readable medium,” where the term “non-transitory” does not include or encompass transitory propagating signals.

[0103] The processor 82 may include one processing device or a plurality of processing devices that are distributed within (or communicatively coupled to) controller 80 or more broadly within the heat pump 10. Likewise, the memory 84 may include one memory device or a plurality of memory devices that are distributed within (or communicatively coupled to) controller 80 or more broadly within the heat pump 10. Thus, the controller 80 may comprise a plurality of individual “controllers” distributed throughout the heat pump 10 and that may be communicatively coupled to one another.

[0104] The controller 80 may be communicatively coupled to various components of the heat pump 10 so that the controller 80 may conduct, control, and direct operation of the heat pump 10 in at least the heating mode (FIG. 1) and the defrost mode (FIG. 3). For instance, the controller 80 may be communicatively coupled to the reversing valve 28 so as to control the flow direction of the refrigerant through the refrigerant circuit 58 during operations. In addition, the controller 80 may be communicatively coupled to the valves 94, 96, sensors 91, 92, blower 48, fan 38, and compressor 30 among other components so as to control one or more operational aspects of the heat pump 10 during the defrost mode (FIG. 3) and the heating mode (FIG. 1) such as described herein.

[0105] Referring now to FIG. 8, a method 300 of operating a heat pump during a defrost mode of operation is shown according to some embodiments. In at least some embodiments, one or more blocks 302-314 of the method 300 may be at least partially performed with a controller, such as the controller 80 shown in FIGS. 1 and 3-7. Thus, the method 300 of FIG. 7 may be representative of at least some of the machine-readable instructions 86 stored on memory 84 and executable by the processor 82 (FIG. 1).

[0106] In describing the features of method 300, continuing reference is made to the heat pump 10 shown in FIGS. 1 and 3. However, it should be appreciated that the method 300 may also be performed by use of either of the heat pumps 110, 210 shown in FIGS. 4-7. In addition, it should also be appreciated that method 300 may be performed by use of other climate control systems, such as other heat pumps, that are different from the heat pumps 10, 110, 210 in at least some respect. Thus, references to the heat pump 10 of FIGS. 1 and 3 when describing the features of method 300 are merely intended to facilitate the description of embodiments of method 300 and should not be interpreted as limiting other implementations thereof.

[0107] The method 300 may be configured to avoid or at least reduce the risk of cold blow into an interior space (e.g., interior space 12) during operation of a heat pump (e.g., heat pump 10) in a defrost mode (FIG. 3). The method 300 may be performed using a heat pump that includes a thermal storage device (e.g., thermal storage device 100) as described herein (e.g., such as is the case for each of the heat pumps 10, 110, 210). However, the method 300 may also be performed using other heat pumps that do not employ a thermal storage device.

[0108] Initially, the method 300 includes actuating a reversing valve to initiate a defrost mode operation at block 302. For instance, as previously described for the heat pump 10 of FIGS. 1 and 3, the heat pump 10 may transition from the heating mode (FIG. 1) to the defrost mode (FIG. 3) by reversing the flow direction of refrigerant in the refrigerant circuit 58. Specifically, the flow direction of the refrigerant along the refrigerant circuit 58 is reversed by actuating the reversing valve 28 to selectively route the refrigerant discharged from the compressor 30 to the outdoor heat exchanger 32 rather than the indoor heat exchanger 44.

[0109] In addition, the method 300 includes adjusting the operating speed of the indoor blower relative to the operating speed of the blower (e.g., blower 48 shown in FIGS. 1 and 3) during the previous heating mode operation. Specifically, in some embodiments, method 300 includes reducing the blower speed at block 304 or reversing the blower direction at block 306.

[0110] Reducing the blower speed at block 304 may include decreasing a speed of the blower relative to the speed at which the blower was operating during the previous heating mode operation. For instance, in some embodiments, the reduction in the blower speed may include operating the blower at a reduced speed that may be in a range of about 5% to about 10% of the previous blower speed during the previous heating mode operation. The reduced blower speed may still produce an airflow (e.g., airflow 50) that is flowed over and / or through the indoor heat exchanger (e.g., heat exchanger 44) and then into the interior space (e.g., interior space 12) albeit at a much-reduced flow rate (compared to the previous heating mode operation). In some embodiments, reducing the blower speed at block 304 may include shutting down the blower entirely so as to stop generating an airflow (e.g., airflow 50) over and / or through the indoor heat exchanger and into the interior space.

[0111] Without being limited to this or any other theory, reducing or stopping the airflow over and / or through the indoor heat exchanger (e.g. the airflow 50 in FIGS. 1 and 3) may reduce the risk of cold blow into the interior space 12 that reduces occupant comfort. Specifically, as previously described, during the defrost mode operation, cool refrigerant may be flowed through the indoor heat exchanger 44 so as to absorb heat that is then used to defrost the outdoor heat exchanger 32. This heat absorption into the refrigerant via the indoor heat exchanger 44 reduces a temperature of the air surrounding the coils of the indoor heat exchanger 44. As a result, reducing or stopping the airflow 50 may minimize or prevent the delivery of this cooled air into the interior space 12 so that occupant comfort is preserved. It has previously been customary to maintain a relatively high air flow rate through the indoor heat exchanger so that heat would be more readily absorbed by the refrigerant for delivery to the outdoor heat exchanger during a defrost operation.

[0112] Alternatively, in some embodiments, the method 300 may reverse the direction of the indoor blower at block 306. Specifically, as previously described for the heat pump 10 of FIGS. 1 and 3, the blower 48 may operate to advance the airflow 50 from the indoor heat exchanger 44 into the interior space 12 during a heating operation (FIG. 1). In block 306 of may comprise operating the blower 48 so that the airflow 50 reverses direction from that depicted in FIG. 1 and instead flows back through the ducting 52 to the indoor heat exchanger 44. The reversed flow direction of the airflow 50 may be accomplished by reversing a rotational direction of an impeller or fan of the blower 48, or by activating a reversing impeller or fan that may or may not be incorporated into the blower 48 and that is specifically configured to induce a reversed airflow direction. Reversing the blower 48 at block 306 may cause airflow to progress from the indoor heat exchanger back out of an air-return duct (not shown) in fluid communication with the interior space (so that reversing the blower in block 306 may still result in a positive airflow into the interior space—but from a reverse direction than during the heating mode operation.

[0113] Without being limited to this or any of theory, and with reference to the heat pump 10 of FIGS. 1 and 3, reversing the blower direction via block 306 may pull airflow 50 that was previously warmed during the previous heating mode operation and that is still contained in the ducting 52 back over the indoor heat exchanger 44. This reversed, warm airflow 50 may then provide heat back to the refrigerant for defrosting the outdoor heat exchanger 32. In addition, portions of the airflow 50 that were flowing into a return-air duct (not shown) may be pushed back into the interior space 12; however, this portion of the airflow 50 may be relatively warmer than airflow 50 that has passed over and / or through the indoor heat exchanger 44 that is circulating the cooled refrigerant during the defrost operation (FIG. 3). As a result, reversing the direction of the blower 48 and thus the direction of the airflow 50 may facilitate heat transfer to the refrigerant to defrost the outdoor heat exchanger 32 while avoiding (or at least reducing) the risk that cooled airflow (resulting from thermal contact with the refrigerant in the indoor heat exchanger 44) is flowed into the interior space as “cold blow.”

[0114] Method 300 also includes reducing the compressor speed at block 308. For instance, reducing the compressor speed at block 308 may comprise reducing the compressor speed relative to an operating speed of the compressor during the previous heating mode operation (FIG. 1). In some embodiments, the reduction in compressor speed at block 308 may include reducing the compressor speed by about 30% to about 70% of the compressor speed during the previously heating mode operation (FIG. 1). Stated differently, the compressor speed during the defrost mode operation (according to block 308) may be about 30% to about 70% of the operating speed of the compressor during the previous heating mode operation. In some embodiments, the compressor speed during the defrost mode may be less than 30% or more than 70% of the compressor speed during the previous heating mode operation. In some specific embodiments involving the heat pump 10, the compressor 30 may initially operate at a speed of about 60 revolutions per second (RPS) during a heating mode operation (FIG. 1). Thereafter, upon the initiation of the defrost operation (FIG. 3), the compressor speed may be reduced to a range of about 20 RPS to about 40 RPS.

[0115] Without being limited to this or any other theory, reducing a speed of the compressor (e.g., compressor 30 in FIGS. 1 and 3) may slow a rate of heat transfer to and from the refrigerant in both the indoor heat exchanger (e.g., heat exchanger 44) and the outdoor heat exchanger (e.g., heat exchanger 32). The slowed rate of heat transfer may still be sufficient for removing ice accumulated onto the outdoor heat exchanger, but may reduce the temperature drop in the indoor heat exchanger so that the risk of cold blow is reduced. In addition, again without being limited to this or any other theory, reducing a speed of the compressor (e.g., compressor 30 in FIGS. 1 and 3) may help to reduce the risk that liquid refrigerant is discharged from the indoor heat exchanger (e.g., hear exchanger 44) to the compressor (e.g., compressor 30) in light of the reduced, stopped, or reversed indoor airflow (e.g., airflow 50). Specifically, reducing a flow rate of refrigerant through the indoor heat exchanger may compensate for the reduced airflow over or through the indoor heat exchanger.

[0116] Method 300 also includes deactivating the outdoor fan at block 310. For instance, with reference to the heat pump 10 of FIGS. 1 and 3, block 310 of method 300 may include deactivating the fan 38 to stop or prevent the airflow 40. Specifically, without being limited to this or any other theory, stopping the airflow 40 (by deactivating fan 38) may slow or stop additional ice formation on the outdoor heat exchanger 32 by reducing the contact between the cool outdoor airflow 40 and the heat exchanger 32 as heat delivered by the refrigerant melts the already accumulated ice.

[0117] Method 300 also includes actuating the reversing valve to end the defrost mode operation and to initiate a heating mode operation at block 312, and increasing the blower speed at block 314. For instance, as previously described for heat pump 10, upon determining that the defrost mode is to end (e.g., such as by the lapsing of a timer, the receipt of a temperature associated with the outdoor heat exchanger 32 that is above a threshold, etc.), the reversing valve 28 may be actuated (e.g., by controller 80) to again reverse the flow of refrigerant along the refrigerant circuit 58. The actuation of the reversing valve 28 may once again route the warm refrigerant discharged from the compressor to the indoor heat exchanger 44 so that the interior space 12 may be warmed via the airflow 50 once again. Thus, block 314 may include actuating the blower 48 to direct the airflow 50 into the interior space 12 via the duct 52 as shown in FIG. 1 (e.g., if the blower 48 was previously reversed via block 306 as previously described) and / or increasing a speed of the blower 48 to that typically associated with normal heating mode operations (FIG. 1).

[0118] In some embodiments, the indoor heat exchanger 32 (or one or more coils thereof) may have been reduced in temperature as a result of the defrost operation. Thus, the increase in the blower speed at block 314 (or even the activation of the blower 48) may be delayed by a set period of time (e.g., 30 seconds in some embodiments) after reversing the flow of the refrigerant via block 312 so that the temperature of indoor heat exchanger 32 may be increased before airflow 50 is directed over and / or through it. Without being limited to this or any other theory, delaying the increase in speed or activation of the blower 48 via block 314 may reduce the risk of cold blow by flowing air over a cooled indoor heat exchanger 32 resulting from the previous defrost mode operation.

[0119] In some embodiments, rather than being incorporated into the indoor or outdoor unit of a heat pump, the thermal storage device may be a separate modular device operable to be attached to a heat pump as needed to facilitate defrosting of an outdoor heat exchanger of the heat pump. FIG. 9 illustrates an example of a thermal storage (TS) module 410 attached to a climate control system 400. The climate control system 400 may be, for example, a HVAC system, a heat pump, such as heat pump 10 described in FIGS. 1-7, a chiller, or other suitable device. As shown in FIG. 9, thermal storage module 410 may be connected to outdoor unit 420 and to the indoor unit 420 via the refrigerant circuit 440. The connection may include an expansion valve (hereinafter “TS EEV”) 412 and a solenoid valve 414. For example, the thermal storage module 410 may be installed along a refrigerant circuit 440 between the outdoor unit 420 and the indoor unit 430. The TS EEV 412 may be coupled to the outdoor unit and the indoor unit via a liquid line 417 along the refrigerant circuit 440 and the solenoid valve 414 may be coupled to the refrigerant circuit piping connecting the outdoor unit and the indoor unit via a gas line 415 along the refrigerant circuit 440 (or via a bypass circuit connecting the liquid line 417 to the gas line 415). The thermal storage defrosting module 410 may also including a heat exchanger 411 discussed more in connection with FIG. 10.

[0120] The thermal storage module 410 may turn on when the climate control system 400 is in the heating mode and the defrost mode and may turn off when the climate control system 400 is in the cooling mode. The on / off of the thermal storage module 410 may be controlled by controller 450. The statuses of the TS EEV 412 and the solenoid valve 414 may also be controlled by controller 450. In some examples, the controller 450 may include a system controller 452 that controls the operations of the climate control system 400 and a thermal storage module controller (hereinafter “TS module controller”) 454 that controls the operations of the thermal storage module 410. In some examples, the controller 450 may be a part of the climate control system 400 or a remote device that communicates with the climate control system 400 and the thermal storage module 410 via a wireless network. In other examples, the system controller 452 and the TS module controller 454 are separate elements. In either case, both the system controller 452 and the TS module controller 454 may communicate with each other via physical wires or wirelessly via Bluetooth, intranet, internet, or cloud, without limitations.

[0121] The connection between the thermal storage module 410 and the climate control system 400 is shown in more detail in FIG. 10. As shown in FIG. 10, the thermal storage module 410 comprises a fluid tank 416 containing thermal energy storage fluid 421 that may be water or glycol fluid, a fluid pump 418 used to circulate a working fluid 423 through the fluid tank 416 so as to exchange thermal energy with the thermal energy storage fluid 421, and a heat exchanger 411 coupled to the refrigerant circuit 440 (shown in FIG. 9) between the outdoor unit 420 and the indoor unit 430 for exchanging thermal energy between the working fluid 423 and a refrigerant flow between the working fluid 423 and a refrigerant flow within the refrigerant circuit. The thermal storage module 410 is located between the indoor unit 430 and the outdoor unit 420, in which the inlet side of the heat exchanger 411 is connected to an outdoor coil 424, and the TS EEV 412 is included on the inlet side. On the outlet side of the heat exchanger 411 is connected to an indoor coil 432 and a bypass line allowing the refrigerant circuit to bypass the indoor unit. In the depicted example, a solenoid valve 414 is included in the bypass line to allow the refrigerant to selectively flow (or not flow) through the bypass line, potentially allow the refrigerant in the refrigerant circuit 440 to selectively bypass the indoor unit.

[0122] The outdoor unit 420 and the indoor unit 430 are similar to those described in heat pump 10 of FIGS. 1-7 as above. Basically, the outdoor unit 420 may comprises a compressor 422, a switchover valve (SOV) 426, an outdoor coil 424, an outdoor EEV or OD EEV 428 controlling the refrigerant flow in / out the outdoor coil 424, and an outdoor fan 429. The TS EEV 412 is coupled to the OD EEV 428, as shown in FIG. 10. The indoor unit 430 comprises an indoor coil 432, an ID EEV or a TXV 434 for controlling the refrigerant flowing in / out the indoor coil 432, and an indoor fan 436 for provide heat / cold air to a conditioned space (not shown.) As shown in FIG. 10, the solenoid valve 414 is coupled between the indoor coil 432 (via ID EEV 434), the SOV 426 and the outlet of the heat exchanger 411 of the thermal storage module 410. According to the present disclosure, the thermal energy storage fluid stored in the fluid tank 416 is a single-phase material, and the TS EEV 412 is coupled between the outdoor coil 424 and the indoor coil 432 via a liquid line 417, while the solenoid valve 414 is coupled between the indoor unit coil 432 and the outdoor coil 424 via a gas line 415. It is understood, however, that in some examples the thermal energy storage fluid may be a two-phased fluid, or phase change material, to allow for increased thermal capacity. In some examples, the working fluid 423 and the thermal energy storage fluid 421 may be the same fluid, and the fluid tank 416 may use stratification to thermally separate the working fluid 423 into and out of the fluid tank. Still other examples may be used.

[0123] FIGS. 11A-11C are flowcharts of methods 500, 520, and 540 illustrating various steps of operation of the thermal storage module 410 when the climate control system 400, to which the thermal storage device is connected, is operating in different operation modes. FIG. 11A depicts method 500 for installing the thermal storage device 410 and operating the thermal storage module 410 during a defrost mode. FIG. 11B depicts method 520 for operating the thermal storage module 410 during a heating mode. Finally, FIG. 11C depicts method 540 for operating the thermal storage module 410 during a cooling mode.

[0124] Method 500 starts with attaching the thermal storage module 410 to the climate control system 400, as shown at step 502. As described above with respect to FIGS. 9-10, the thermal storage module 410 may be installed between the outdoor unit 420 and the indoor unit 430. The thermal storage module 410 may be an independent device that is attachable to the climate control system 400 when needed. For example, TS module 410 may be attached between an outdoor unit and an indoor unit of a climate control system, as shown in FIG. 9. In certain embodiments, attaching the thermal storage module 410 at step 502 may further include attaching an expansion valve, e.g., TS EEV 412, between an inlet of the heat exchanger 411 and the outdoor unit 420 and attaching a solenoid valve, e.g., solenoid valve 414, between the outlet of the heat exchanger 411 and the indoor unit 420 (or a bypass line). The TS EEV 412 may be fluidly coupled to the refrigerant circuit 440. The solenoid valve 414 may be further coupled to the outdoor unit 420 and is fluidly coupled to the refrigerant circuit 440.

[0125] Method 500 may include, at step 504, coupling the TS module controller 454 to the system controller 452 such that the TS controller 454 and system controller 452 are in communication with each other. The TS module controller 454 may be configured to control the expansion valve, e.g., TS EEV 412, the solenoid valve 414, and the fluid pump 418. The TS controller 454 may be communicatively coupled with system controller 452 wirelessly or via wires so that the TS module controller 454 can control the thermal storage module 410 upon receiving signals from the system controller 452. According to the present disclosure, the thermal storage module 410 is mainly used to defrost the outdoor unit 420 or the outdoor coil 424 when receiving a defrost signal from the system controller 452. The thermal storage module 410 is also activated when the climate control system 400 is operating in a heating mode. In heating mode, the heat pump 418 of the thermal storage device 410 facilitates heat transfer from the refrigerant to fluid stored in the fluid tank 416 via the heat exchanger 411 to charge the thermal energy storage fluid 421 stored in the fluid tank 416. Method 500 shown in FIG. 11A explains the defrost mode first. However, it is understood that the thermal storage module 410 is charged when the climate control system 400 is operating in the heating mode, which is further explained by method 520 shown in FIG. 11B. In method 500 shown in FIG. 11A, it is assumed that the fluid tank 416 has stored a predetermined amount of heat that is sufficient to defrost the outdoor unit 420.

[0126] In step 506 of method 500, the TS controller 454 receives a control signal from the climate control system indicating the climate control system is operating at the defrost mode. Then at step 508, upon receiving the control signal indicating that defrost mode is required, the TS module controller 454 opens both the TS EEV 412, the solenoid valve 414 and turns on the fluid pump 418.

[0127] Therefore, at step 510, since both the TS EEV 412 and the solenoid valve 414 are opened, the refrigerant is directed to flow from the compressor 422 along the refrigerant circuit 440 to the outdoor coil 424, the heat exchanger 411 of the thermal storage module 410 via the TS EEV 412, then back to the compressor through the solenoid valve 414, bypassing the indoor unit 430. At the same time, the fluid pump 418 circulate the fluid through the TS heat exchanger 411. Here, the solenoid valve 414 works as a bypass valve for preventing the refrigerant from flowing into the indoor unit 430. Note it is understood that the EEV in the indoor unit and / or other valves may be used to ensure the flow of the refrigerant bypasses the indoor unit. Still other examples may be used.

[0128] At step 512, method 500 may include activating the fluid pump based on a control signal from the TS controller in order to facilitate heat transfer from the TES fluid in the fluid tank to the refrigerant via the heat exchanger such that the heated refrigeration defrosts the outdoor coil of the outdoor unit. Accordingly, at step 512, the expansion valve 412 is running superheat control and the heat pump 418 of the thermal storage module 410 facilitates heat transfer from the thermal energy storage fluid of the fluid tank 416 to the refrigerant via the heat exchanger 411. The heat exchanger 411, in the defrost mode, operates as an evaporator to heat the refrigerant for defrosting / melting ice on the outdoor coil 424 of the outdoor unit 420. According to the present disclosure, since the thermal storage module 410 is able to provide sufficient heat for defrosting the outdoor coil 424, there is no need to take heat from the indoor unit 430, or for the use of an additional heating element at the indoor unit 430 to avoid cold blow, or for the use of an additional heating element in the outdoor unit 420 for defrosting the outdoor coil 424.

[0129] FIG. 11 B depicts method 520 showing various steps when the climate control system 400 is operating in the heating mode. Method 520 starts with receiving a control signal from the climate control system, e.g., the system controller 452, indicating the climate control system is operating in a heating mode, as shown at step 522.

[0130] At step 524 of method 520, in response to the control signal received at step 522, the TS EEV 412 is opened and the solenoid valve closed. At step 526, method 520 includes directing the refrigerant from the compressor 422 along the refrigerant circuit 440 to the indoor coil 432 of the indoor unit 430 and then back to the compressor 422.

[0131] At this time, the fluid pump 418 of the thermal storage module 410 is activated to facilitate heat transfer from the refrigerant to the thermal energy storage fluid 421 stored in the fluid tank 416 via the heat exchanger 411, as shown at step 528. This step may be considered as a charging step, in which the heat received from the heat exchanger 411 is stored in the fluid tank 416. The heat will be used later during the defrost mode to defrost the outdoor coil 424 of the outdoor unit 420. In some examples, this charging only occurs where the climate control system has excess capacity to meet the required conditioning demand. In some examples, this charging occurs during off-peak hours and / or lower-energy pricing times. Other controls may also be utilized.

[0132] Further, at step 530, once a predetermined amount of heat has been stored in the fluid tank 416, the fluid pump 418 is deactivated so as to stop the heat transfer from the refrigerant to the thermal energy storage fluid stored in the fluid tank 416 via the heat exchanger 411. The predetermined amount of heat is set to be sufficient for use in the defrost mode to defrost the outdoor coil 424 of the outdoor unit 420. It is noted that when the amount of heat stored in the fluid tank 416 is below the predetermined amount, the fluid pump is again activated, provided that the climate control system 400 is either operating in the defrost mode or in the heating mode, to recharge the fluid tank 416. As described above, the fluid pump 418 is activated only when the climate control system 400 is operating in the heating and defrost modes and is deactivated when the climate control system 400 is operating in the cooling mode, which is described further in FIG. 11C.

[0133] FIG. 11C depicts method 540 showing various steps when the climate control system 400 is operating in the cooling mode. As shown at step 542, method 540 starts with receiving, by the thermal storage module 410, e.g., the TS controller 454, a control system from the climate control system 400 indicating that the climate control system 400 is operating in the cooling mode. In response, method 540 opens the TS EEV 412 and closes the solenoid valve 414 at step 544 and deactivates the fluid pump 418 at step 546. At this time, the heat exchanger 411 will not actively transfer heat, and in some examples a refrigerant line may be included to bypass the heat exchanger 411 for this operation. At step 548 of method 540, the refrigerant from the compressor 422 of the outdoor unit 420 is directed to the outdoor coil 424, the heat exchanger 411 of the thermal storage module 410 working as a flowing path of the refrigerant without heat transfer, the indoor coil 432 of the indoor unit 430, and back to the compressor 422. That is, the climate control system 400 would work in the normal cooling mode and the thermal storage device does not function at all.

[0134] It is to be understood that methods 500, 520, and 540 may be performed by controller 450, e.g., system controller 452 and TS controller 454. As described above, the TS controller 454 and the system controller 452 may communicate with each other to exchange control signals. Based on the control signals, the TS controller 454 is configured to activate the fluid pump 418 in both the heating and defrost modes and deactivate the fluid pump 418 in the cooling mode. The TS controller 454 is further configured to open or close the TS EEV 412 and the solenoid valve 414 based on the operation mode. Moreover, as the thermal storage module 410 may be an independent modular device from the climate control system 400, the thermal storage module 410 can be easily attached to different types of climate control systems without the need to update or revise the existing climate control structures or systems.

[0135] Clause 1: A heat pump for conditioning an interior space, the heat pump comprising: an outdoor unit comprising: an outdoor heat exchanger that is configured to exchange heat between a refrigerant and an outdoor environment; an outdoor expansion device that is configured to expand the refrigerant flowing into the outdoor heat exchanger when the heat pump is operating in a heating mode; an indoor unit comprising: an indoor heat exchanger that is configured to exchange heat between the refrigerant and the interior space; and an indoor expansion device that is configured to expand the refrigerant flowing into the indoor heat exchanger when the heat pump is operating in a defrost mode; a thermal storage device in fluid communication between the outdoor expansion device and the indoor expansion device; and a reversing valve that is actuatable between: a first position during the heating mode to direct refrigerant through the indoor heat exchanger, the thermal storage device, the outdoor expansion device, and then the outdoor heat exchanger to heat the interior space and to transfer heat from the refrigerant to the thermal storage device; and a second position during the defrost mode to direct refrigerant through the outdoor heat exchanger and then the thermal storage device to transfer thermal energy to the outdoor heat exchanger from the thermal storage device.

[0136] Clause 2: The heat pump of any of the clauses, wherein the thermal storage device comprises a phase change material that is configured to at least partially change phase to transfer heat to and from the refrigerant.

[0137] Clause 3: The heat pump of any of the clauses, further comprising a bypass line that is configured to bypass refrigerant emitted from the thermal storage device around the indoor expansion device and the indoor heat exchanger to the reversing valve when the reversing valve is in the second position.

[0138] Clause 4: The heat pump of any of the clauses, further comprising a defrost expansion device positioned in the outdoor unit, downstream of the outdoor expansion device, wherein the defrost expansion device is configured to expand the refrigerant flowing into the thermal storage device when the reversing valve is in the second position.

[0139] Clause 5: The heat pump of any of the clauses, wherein the indoor unit includes a blower that is configured to generate an airflow that is directed through the indoor heat exchanger and then to the interior space, and wherein the heat pump further comprises a controller that is communicatively coupled to the blower and that is configured to terminate operation of the blower during the defrost mode.

[0140] Clause 6: The heat pump of any of the clauses, further comprising a compressor that is configured to compress the refrigerant, wherein the controller is also communicatively coupled to the compressor and is configured to reduce an operating speed of the compressor during the defrost mode relative to the heating mode.

[0141] Clause 7: The heat pump of any of the clauses, wherein the thermal storage device is positioned in the outdoor unit.

[0142] Clause 8: The heat pump of any of the clauses, further comprising a second bypass line that bypasses the thermal storage device between the outdoor expansion device and the indoor expansion device.

[0143] Clause 9: A method of operating a heat pump to condition an interior space, the heat pump including an outdoor heat exchanger to exchange heat between a refrigerant and an outdoor environment, an outdoor expansion device, an indoor heat exchanger to exchange heat between the refrigerant and the interior space, and an indoor expansion device, wherein the method comprises: (a) routing the refrigerant through the indoor heat exchanger, a thermal storage device, the outdoor expansion device, and then an outdoor heat exchanger to heat the interior space via the indoor heat exchanger and to transfer heat from the refrigerant to the thermal storage device, the thermal storage device being in fluid communication between the indoor expansion device and the outdoor expansion device; and (b) routing the refrigerant through the outdoor heat exchanger and then the thermal storage device to transfer thermal energy to the outdoor heat exchanger from the thermal storage device.

[0144] Clause 10: The method of any of the clauses, further comprising: (c) at least partially transitioning a phase change material in the thermal storage device from solid state to liquid state during (a); and (d) at least partially converting the phase change material in the thermal storage device from liquid phase to solid phase during (b).

[0145] Clause 11: The method of any of the clauses, further comprising: (e) bypassing the indoor heat exchanger after (b) to return the refrigerant to a compressor of the heat pump.

[0146] Clause 12: The method of any of the clauses, further comprising: (f) expanding the refrigerant between the outdoor heat exchanger and the thermal storage device during (b).

[0147] Clause 13: The method of any of the clauses, further comprising: (g) operating a blower during (a) to induce an airflow through the indoor heat exchanger; and (h) terminating operation of the blower during (b).

[0148] Clause 14: The method of any of the clauses, (i) compressing the refrigerant with a compressor during (a) and (b); (j) operating the compressor at a first operating speed during (a); and (k) operating the compressor at a second operating speed that is less than the first operating speed during (b).

[0149] Clause 15: A heat pump for conditioning an interior space, the heat pump comprising: an outdoor unit comprising: an outdoor heat exchanger that is configured to exchange heat between a refrigerant and an outdoor environment; an indoor unit comprising: an indoor heat exchanger that is configured to exchange heat between the refrigerant and the interior space; an indoor expansion device that is configured to expand the refrigerant; and a thermal storage device that is configured to exchange heat between the refrigerant and a thermal storage medium; and valving that is actuatable to operate the heat pump in: a heating mode in which refrigerant is flowed through the indoor heat exchanger and the thermal storage device in parallel and then is flowed to the outdoor unit to heat the interior space via the indoor heat exchanger and to transfer heat from the refrigerant to the thermal storage medium of the thermal storage device; and a defrost mode in which refrigerant is flowed through the outdoor heat exchanger and then is flowed through the thermal storage device in bypass of the indoor heat exchanger to transfer heat from the thermal storage medium of the thermal storage device to the outdoor heat exchanger.

[0150] Clause 16: The heat pump of any of the clauses, wherein the thermal storage medium is configured to at least partially change state from solid to liquid during the heating mode and is configured to at least partially change state from liquid to solid during the defrost mode.

[0151] Clause 17: The heat pump of any of the clauses, wherein the valving is actuatable to flow the refrigerant through an indoor expansion device before flowing the refrigerant through the thermal storage device in the defrost mode.

[0152] Clause 18: The heat pump of any of the clauses, wherein the valving is actuatable to return the refrigerant to a compressor after flowing through the thermal storage device in the defrost mode.

[0153] Clause 19: The heat pump of any of the clauses, wherein the indoor unit includes a blower that is configured to generate an airflow that is directed through the indoor heat exchanger and then to the interior space, and wherein the heat pump further comprises a controller that is communicatively coupled to the blower and that is configured to terminate operation of the blower during the defrost mode.

[0154] Clause 20: The heat pump of any of the clauses, wherein the controller is also communicatively coupled to the compressor and is configured to reduce an operating speed of the compressor in the defrost mode relative to the heating mode.

[0155] Clause 21: A thermal storage module in fluid communication with an outdoor unit and an indoor unit of a climate control system, the climate control system comprising a refrigerant circuit for directing a refrigerant flowing between the indoor unit and the outdoor unit, the outdoor unit comprising a compressor, wherein the thermal storage module comprises: a fluid tank containing a thermal energy storage fluid; a fluid pump configured to circulate a working fluid through the fluid tank, the working fluid exchanging thermal energy with the thermal energy storage fluid; a heat exchanger fluidly coupled to the refrigerant circuit between the outdoor unit and the indoor unit, the heat exchanger configured to exchange thermal energy between the working fluid and a refrigerant flow within the refrigerant circuit; an expansion valve coupled to the refrigerant circuit between the heat exchanger and the outdoor unit; and a controller configured to control the fluid pump based on an operation mode of the climate control system, wherein the fluid pump is configured to be activated when the climate control system is operating in a heating mode or in a defrosting mode, and the fluid pump is configured to be deactivated when the climate control system is operating in a cooling mode; and wherein the thermal storage module is separate from the indoor unit and the outdoor unit and located along the refrigerant circuit therebetween.

[0156] Clause 22: The thermal storage module according to any of the clauses, wherein: the controller is configured to activate or deactivate the fluid pump based on mode of operation signals received from the climate control system.

[0157] Clause 23: The thermal storage module according to any of the clauses, wherein the thermal energy storage fluid is a phase-change material.

[0158] Clause 24: The thermal storage module according to any of the clauses, further comprising a solenoid valve coupled to the refrigerant circuit between the heat exchanger and the indoor unit, the solenoid valve configured to bypass the refrigerant such that the refrigerant is prevented from flowing into the indoor unit when the climate control system is in a defrost mode.

[0159] Clause 25: The thermal storage module according to any of the clauses, wherein the controller is configured to open or close the expansion valve and the solenoid valve based on an operation mode of the control system, the operation mode selected from heating mode, cooling mode, and defrost mode, such that: upon receiving a control signal from the climate control system that the climate control system is operating in heating mode, the controller is configured to open the expansion valve and close the solenoid valve; upon receiving a control signal from the climate control system that the climate control system is operating in cooling mode, the controller is configured to open the expansion valve and close the solenoid valve; and upon receiving a control signal from the climate control system that the climate control system is operating in defrost mode, the controller is configured to open the expansion valve and open the solenoid valve.

[0160] Clause 26: The thermal storage module according to any of the clauses, wherein, when the climate control system is in a heating mode: the expansion valve is opened and the solenoid valve is closed; the refrigerant is directed from the compressor along the refrigerant circuit to the indoor coil of the indoor unit, the heat exchanger of the thermal storage module, the outdoor coil of the outdoor unit, and back to the compressor; the fluid pump is activated to facilitate heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger; and the fluid pump is deactivated to stop the heat transfer from the refrigerant to the thermal energy storage fluid stored in the fluid tank via the heat exchanger, when a predetermined amount of heat has been stored in the tank.

[0161] Clause 27: The thermal storage module according to any of the clauses, wherein, when the climate control system is in a defrost mode; both the expansion valve and the solenoid valve are opened; and the refrigerant is directed from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the heat exchanger, and back to the compressor via the solenoid valve so as to bypass the indoor unit.

[0162] Clause 28: The thermal storage module according to any of the clauses, wherein, when the climate control system is in a defrost mode: the fluid pump is activated to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger; and the heat exchanger operates as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

[0163] Clause 29: A climate control system, comprising: an indoor unit; an outdoor unit; a refrigerant circuit for directing a refrigerant flowing between the indoor unit and the outdoor unit, the outdoor unit comprising a compressor; a thermal storage device in fluid communication with the outdoor unit and the indoor unit, the thermal storage device comprising: a fluid pump; a fluid tank coupled to the fluid pump and storing a fluid; a heat exchanger fluidly coupled to the refrigerant circuit between an outdoor coil of the outdoor unit and an indoor coil of the indoor unit; an expansion valve coupled to the refrigerant circuit between an inlet of the heat exchanger and the outdoor unit; a solenoid valve coupled to the refrigerant circuit between an outlet of the heat exchanger and an indoor coil of the indoor unit; and a controller configured to control the fluid pump based on an operation mode of the climate control system, wherein the fluid pump is configured to be activated when the climate control system is operating in a heating mode or in a defrosting mode, and the fluid pump is configured to be deactivated when the climate control system is operating in a cooling mode; and wherein the thermal storage module is separate from the indoor unit and the outdoor unit and located along the refrigerant circuit therebetween.

[0164] Clause 30: The climate control system according to any of the clauses, wherein the fluid is a thermal energy storage fluid or a phase-change material.

[0165] Clause 31: The climate control system according to any of the clauses, wherein the expansion valve is coupled to the outdoor unit and the indoor unit via a liquid line along the refrigerant circuit and the solenoid valve is coupled to the outdoor unit and the indoor unit via a gas line along the refrigerant circuit.

[0166] Clause 32: The climate control system according to any of the clauses, wherein when the climate control system is in a heating mode, the expansion valve is opened and the solenoid valve is closed, the refrigerant is directed from the compressor along the refrigerant circuit to the indoor coil of the indoor unit, the heat exchanger of the thermal storage module, the outdoor coil of the outdoor unit, and back to the compressor, the fluid pump is activated to facilitate heat from the refrigerant to fluid stored in the fluid tank via the heat exchanger, and the fluid pump is deactivated to stop the heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger when a predetermined amount of heat is stored in the tank.

[0167] Clause 33: The climate control system according to any of the clauses, wherein, when the climate control system is in a defrost mode, both the expansion valve and the solenoid valve are opened, and the refrigerant is directed from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the heat exchanger, and back to the compressor via the solenoid valve so as to bypass the indoor unit.

[0168] Clause 34: The climate control system according to any of the clauses, wherein, wherein the climate control system is in a defrost mode, the fluid pump is activated to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger, and the heat exchanger operates as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

[0169] Clause 35: A method of operating a defrost mode for a climate control system, the climate control system comprising a refrigerant circuit for directing a refrigerant flowing between an indoor unit and an outdoor unit, the outdoor unit comprising a compressor, and a thermal storage module located between the indoor unit and the outdoor unit, the method comprising: activating or deactivating the thermal storage module based on one or more mode of operation signals received from the climate control system; and directing, when the climate control system is in a defrost mode, the refrigerant from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the thermal storage module, and back to the compressor via the solenoid valve so as to bypass the indoor unit.

[0170] Clause 36: The method according to any of the clauses, wherein the thermal storage module comprises: a fluid pump; a fluid tank coupled to the fluid pump and storing a fluid; a heat exchanger fluidly coupled to the refrigerant circuit between an outdoor coil of the outdoor unit and an indoor coil of the indoor unit; an expansion valve coupled to the refrigerant circuit between an inlet of the heat exchanger and the outdoor unit; a solenoid valve coupled to the refrigerant circuit between an outlet of the heat exchanger and an indoor coil of the indoor unit; and a controller configured to control the fluid pump based on an operation mode of the climate control system, wherein the expansion valve is coupled to the outdoor unit and the indoor unit via a liquid line along the refrigerant circuit and the solenoid valve is coupled to the outdoor unit and the indoor unit via a gas line along the refrigerant circuit.

[0171] Clause 37: The method according to any of the clauses, further comprising, when the climate control system is in the defrosting mode: opening both the expansion valve and the solenoid valve; activating the fluid pump to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger, and operating the heat exchanger as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

[0172] Clause 38: The method according to any of the clauses, further comprising: installing the thermal storage module along the refrigerant circuit between the indoor unit and the outdoor unit, wherein the thermal storage module is separate unit from the indoor unit and the outdoor unit.

[0173] Clause 39: The method according to any of the clauses, further comprising, when the climate control system is in a heating mode: opening the expansion valve and closing the solenoid valve; directing the refrigerant from the compressor of the outdoor unit along the refrigerant circuit to the indoor coil of the indoor unit, to the heat exchanger of the thermal storage module, to the outdoor coil of the outdoor unit, and back to the compressor of the outdoor unit; and activating the fluid pump of the thermal storage module to facilitate heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger.

[0174] Clause 40: The method according to any of the clauses, further comprising deactivating the fluid pump of the thermal storage module when the climate control system is in a cooling mode.

[0175] Clause 41: The method according to any of the clauses, further comprising: opening the expansion valve and closing the solenoid valve; and directing the refrigerant from the compressor of the outdoor unit to the outdoor coil of the outdoor unit, the heat exchanger of the thermal storage unit, an indoor coil of the indoor unit, and back to the compressor of the outdoor unit.

[0176] Embodiments disclosed herein include systems and methods for defrosting an outdoor heat exchanger of a heat pump while preserving occupant comfort and promoting improved operating efficiency. In some embodiments, the systems and methods may utilize a thermal storage device that may store thermal energy for transfer to the refrigerant during a defrost mode to both support the defrost operations and to reduce or eliminate cold blow. In addition, some embodiments may include methods for operating a heat pump that may also reduce or prevent a cool or cold airflow to the interior space during a defrost operation. Thus, by use of the embodiments disclosed herein, a heat pump may manage ice accumulation on the outdoor heat exchanger without substantially effecting occupant comfort and while maintaining the operating efficiency.

[0177] 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.

[0178] 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.

[0179] 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.

[0180] 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.

Claims

1. A thermal storage module in fluid communication with an outdoor unit and an indoor unit of a climate control system, the climate control system comprising a refrigerant circuit for directing a refrigerant flowing between the indoor unit and the outdoor unit, the outdoor unit comprising a compressor, wherein the thermal storage module comprises:a fluid tank containing a thermal energy storage fluid;a fluid pump configured to circulate a working fluid through the fluid tank, the working fluid exchanging thermal energy with the thermal energy storage fluid;a heat exchanger fluidly coupled to the refrigerant circuit between the outdoor unit and the indoor unit, the heat exchanger configured to exchange thermal energy between the working fluid and a refrigerant flow within the refrigerant circuit;an expansion valve coupled to the refrigerant circuit between the heat exchanger and the outdoor unit; anda controller configured to control the fluid pump based on an operation mode of the climate control system,wherein the fluid pump is configured to be activated when the climate control system is operating in a heating mode or in a defrosting mode, and the fluid pump is configured to be deactivated when the climate control system is operating in a cooling mode; andwherein the thermal storage module is separate from the indoor unit and the outdoor unit and located along the refrigerant circuit therebetween.

2. The thermal storage module of claim 1, wherein:the controller is configured to activate or deactivate the fluid pump based on mode of operation signals received from the climate control system; andthe thermal energy storage fluid is a phase-change material.

3. The thermal storage module of claim 1, further comprising a solenoid valve coupled to the refrigerant circuit between the heat exchanger and the indoor unit, the solenoid valve configured to bypass the refrigerant such that the refrigerant is prevented from flowing into the indoor unit when the climate control system is in a defrost mode.

4. The thermal storage module of claim 3, wherein the controller is configured to open or close the expansion valve and the solenoid valve based on an operation mode of the control system, the operation mode selected from heating mode, cooling mode, and defrost mode, such that:upon receiving a control signal from the climate control system that the climate control system is operating in heating mode, the controller is configured to open the expansion valve and close the solenoid valve;upon receiving a control signal from the climate control system that the climate control system is operating in cooling mode, the controller is configured to open the expansion valve and close the solenoid valve; andupon receiving a control signal from the climate control system that the climate control system is operating in defrost mode, the controller is configured to open the expansion valve and open the solenoid valve.

5. The thermal storage module of claim 3, wherein, when the climate control system is in a heating mode:the expansion valve is opened and the solenoid valve is closed;the refrigerant is directed from the compressor along the refrigerant circuit to the indoor coil of the indoor unit, the heat exchanger of the thermal storage module, the outdoor coil of the outdoor unit, and back to the compressor;the fluid pump is activated to facilitate heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger; andthe fluid pump is deactivated to stop the heat transfer from the refrigerant to the thermal energy storage fluid stored in the fluid tank via the heat exchanger, when a predetermined amount of heat has been stored in the tank.

6. The thermal storage module of claim 1, wherein, when the climate control system is in a defrost mode;both the expansion valve and the solenoid valve are opened; andthe refrigerant is directed from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the heat exchanger, and back to the compressor via the solenoid valve so as to bypass the indoor unit.

7. The thermal storage module of claim 6, wherein, when the climate control system is in a defrost mode:the fluid pump is activated to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger; andthe heat exchanger operates as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

8. A climate control system, comprising:an indoor unit;an outdoor unit;a refrigerant circuit for directing a refrigerant flowing between the indoor unit and the outdoor unit, the outdoor unit comprising a compressor;a thermal storage device in fluid communication with the outdoor unit and the indoor unit, the thermal storage device comprising:a fluid pump;a fluid tank coupled to the fluid pump and storing a fluid;a heat exchanger fluidly coupled to the refrigerant circuit between an outdoor coil of the outdoor unit and an indoor coil of the indoor unit;an expansion valve coupled to the refrigerant circuit between an inlet of the heat exchanger and the outdoor unit;a solenoid valve coupled to the refrigerant circuit between an outlet of the heat exchanger and an indoor coil of the indoor unit; anda controller configured to control the fluid pump based on an operation mode of the climate control system,wherein the fluid pump is configured to be activated when the climate control system is operating in a heating mode or in a defrosting mode, and the fluid pump is configured to be deactivated when the climate control system is operating in a cooling mode; andwherein the thermal storage module is separate from the indoor unit and the outdoor unit and located along the refrigerant circuit therebetween.

9. The climate control system of claim 8, wherein the fluid is a thermal energy storage fluid or a phase-change material.

10. The climate control system of claim 8, wherein the expansion valve is coupled to the outdoor unit and the indoor unit via a liquid line along the refrigerant circuit and the solenoid valve is coupled to the outdoor unit and the indoor unit via a gas line along the refrigerant circuit.

11. The climate control system of claim 8, wherein when the climate control system is in a heating mode,the expansion valve is opened and the solenoid valve is closed,the refrigerant is directed from the compressor along the refrigerant circuit to the indoor coil of the indoor unit, the heat exchanger of the thermal storage module, the outdoor coil of the outdoor unit, and back to the compressor,the fluid pump is activated to facilitate heat from the refrigerant to fluid stored in the fluid tank via the heat exchanger, andthe fluid pump is deactivated to stop the heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger when a predetermined amount of heat is stored in the tank.

12. The climate control system of claim 8, wherein, when the climate control system is in a defrost mode,both the expansion valve and the solenoid valve are opened, andthe refrigerant is directed from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the heat exchanger, and back to the compressor via the solenoid valve so as to bypass the indoor unit.

13. The climate control system of claim 12, wherein, wherein the climate control system is in a defrost mode,the fluid pump is activated to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger, andthe heat exchanger operates as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

14. A method of operating a defrost mode for a climate control system, the climate control system comprising a refrigerant circuit for directing a refrigerant flowing between an indoor unit and an outdoor unit, the outdoor unit comprising a compressor, and a thermal storage module located between the indoor unit and the outdoor unit, the method comprising:activating or deactivating the thermal storage module based on one or more mode of operation signals received from the climate control system; anddirecting, when the climate control system is in a defrost mode, the refrigerant from the compressor along the refrigerant circuit to an outdoor coil of the outdoor unit, to the thermal storage module, and back to the compressor via the solenoid valve so as to bypass the indoor unit.

15. The method of claim 14, wherein the thermal storage module comprises:a fluid pump;a fluid tank coupled to the fluid pump and storing a fluid;a heat exchanger fluidly coupled to the refrigerant circuit between an outdoor coil of the outdoor unit and an indoor coil of the indoor unit;an expansion valve coupled to the refrigerant circuit between an inlet of the heat exchanger and the outdoor unit;a solenoid valve coupled to the refrigerant circuit between an outlet of the heat exchanger and an indoor coil of the indoor unit; anda controller configured to control the fluid pump based on an operation mode of the climate control system,wherein the expansion valve is coupled to the outdoor unit and the indoor unit via a liquid line along the refrigerant circuit and the solenoid valve is coupled to the outdoor unit and the indoor unit via a gas line along the refrigerant circuit.

16. The method of claim 15, further comprising, when the climate control system is in the defrosting mode:opening both the expansion valve and the solenoid valve;activating the fluid pump to facilitate heat transfer from the fluid in the fluid tank to the refrigerant via the heat exchanger, andoperating the heat exchanger as an evaporator to heat the refrigerant for defrosting the outdoor coil of the outdoor unit.

17. The method of claim 14, further comprising:installing the thermal storage module along the refrigerant circuit between the indoor unit and the outdoor unit,wherein the thermal storage module is separate unit from the indoor unit and the outdoor unit.

18. The method of claim 14, further comprising, when the climate control system is ina heating mode:opening the expansion valve and closing the solenoid valve;directing the refrigerant from the compressor of the outdoor unit along the refrigerant circuit to the indoor coil of the indoor unit, to the heat exchanger of the thermal storage module, to the outdoor coil of the outdoor unit, and back to the compressor of the outdoor unit; andactivating the fluid pump of the thermal storage module to facilitate heat transfer from the refrigerant to fluid stored in the fluid tank via the heat exchanger.

19. The method of claim 14, further comprising deactivating the fluid pump of the thermal storage module when the climate control system is in a cooling mode.

20. The method of claim 19, further comprising:opening the expansion valve and closing the solenoid valve; anddirecting the refrigerant from the compressor of the outdoor unit to the outdoor coil of the outdoor unit, the heat exchanger of the thermal storage unit, an indoor coil of the indoor unit, and back to the compressor of the outdoor unit.

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