EP3169950A1

EP3169950A1 - Heat pump system

Info

Publication number: EP3169950A1
Application number: EP14897735.8A
Authority: EP
Inventors: Wei Liu
Original assignee: Electrolux Hangzhou Domestic Appliances Co Ltd
Current assignee: Electrolux Hangzhou Domestic Appliances Co Ltd
Priority date: 2014-07-17
Filing date: 2014-07-17
Publication date: 2017-05-24
Also published as: NZ728139A; AU2014401283A1; WO2016008134A1; WO2016008134A8; EP3169950A4; US20170211861A1

Abstract

Provided is a heat pump system (10, 10A) for a conditioned space comprising a first thermal fluid circuit adapted to selectably operate to circulate a thermal fluid therein, and a second thermal fluid circuit adapted to selectably operate to circulate the thermal fluid therein. The first thermal fluid circuit may comprise a compressor (15), a first heat exchanger (11), and a passage (55) of a heat accumulator (50). The second thermal fluid circuit may bypass the first heat exchanger (11), or the passage (55) of the heat accumulator (50), or both. The second thermal fluid circuit may comprise the compressor (15), and a second heat exchanger (12).

Description

HEAT PUMP SYSTEM

TECHNICAL FIELD

[0001] The present invention generally relates to a heat pump system. More particularly, the present invention relates to a heat pump system employing a heat accumulator to defrost a heat exchanger in the system. Most particularly, the present invention relates to a heat pump system, where the accumulator obtains waste heat from the compressor in the system.

BACKGROUND

[0002] A heat pump is a device that transfers thermal energy from a heat source to a heat sink. Heat pumps can move thermal energy in a direction opposite to the direction of the spontaneous heat flow. A heat pump uses energy to accomplish the desired transfer of thermal energy from heat source to heat sink.

[0003] Compressor driven air conditioners are one example of a heat pump; however, the term heat pump is more general and applies to devices which are adapted for use for space heating, or space cooling. When a heat pump is used for heating, it may use the same basic refrigeration cycle employed by an air conditioner or a refrigerator, with the difference that it outputs heat into the conditioned space rather than into the surrounding environment. In this use, heat pumps generally absorb heat from a heat source region, such as, without limitation, cooler external air or from the ground. Heat pumps are sometimes used to provide heating because less high grade (low entropy) energy is required for their operation than appears in the output heat. That is, in a heat pump, much or most of the energy for heating may be absorbed from a heat source region and only a small fraction of the energy for heating needs to come from electricity or some other high grade energy source. Because the heat output to the heat sink may comprise both the heat absorbed from the heat source, and the high grade heat consumed to transfer of thermal energy from heat source region to heat sink region, the heat output may be several times larger than the high grade energy consumed. As a consequence, the system coefficient of performance (COP) of a heat pump may be substantially greater than 1. The system coefficient of performance (COP) of some heat pumps may be 3 or 4. [0004] One issue in operation of known heat pumps is that the heat exchanger absorbing heat from a heat source region may frost when operating in low temperature environments. To defrost the frosted heat exchanger, some heat pumps may stop heating the heat sink region and switch to absorbing heat from the previous heat sink region to provide heat to defrost the frosted heat exchanger. Where the previous heat sink region is a conditioned space that is desirable to heat or keep warm, this removal of heat to defrost the frosted heat exchanger is undesirable and may result in an uncomfortable or undesired decrease in temperature.

SUMMARY OF THE INVENTION

[0005] Provided is a heat pump system for a conditioned space comprising a first thermal fluid circuit adapted to selectably operate to circulate a thermal fluid therein, and a second thermal fluid circuit adapted to selectably operate to circulate the thermal fluid therein. The first thermal fluid circuit may comprise a compressor, a first heat exchanger, and a passage of a heat accumulator. The second thermal fluid circuit may bypass the passage of the heat accumulator. The second thermal fluid circuit may comprise the compressor, and a second heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Fig. 1 is a schematic diagram of a heat pump system in accordance with the present invention depicted in a cooling mode of operation.

[0007] Fig. 2 is a schematic diagram similar to Fig. 1 depicted in a heating mode of operation.

[0008] Fig. 3 is a schematic diagram similar to Fig. 1 depicted in a defrosting mode of operation.

[0009] Fig. 1A is a schematic diagram mostly similar to Fig. 1 differing in the embodiment of the heat accumulator shown and depicted in a cooling mode of operation.

[0010] Fig. 2A is a schematic diagram mostly similar to Fig. 1 differing in the embodiment of the heat accumulator shown and depicted in a heating mode of operation.

[0011] Fig. 3A is a schematic diagram mostly similar to Fig. 1 differing in the embodiment of the heat accumulator shown and depicted in a defrosting mode of operation.

[0012] The following description and the annexed drawings set forth in detail certain illustrative aspects of the claimed subject matter. These aspects are indicative, however, of but a few of the various ways in which the principles of the innovation may be employed and the claimed subject matter is intended to include all such aspects and their equivalents. Other advantages and novel features of the claimed subject matter will become apparent from the following detailed description of the innovation when considered in conjunction with the drawings.

DETAILED DESCRIPTION

[0013] A heat pump system according to the concepts of the present subject matter is generally indicated by the numbers 10, 10A in the drawings. Heat pump system 10, 10A includes a first heat exchanger 11, which is in communication with a conditioned space. As the term is used herein, unless otherwise noted, a "conditioned space" may be any region that is heated or cooled by the operation of the heat pump system 10, 10A. A conditioned space refers to the region to which or from which the heat pump system 10, 10A is adapted to pump heat. Without limitation, in some embodiments the conditioned space may be a room, building, vehicle interior, refrigerator interior, freezer interior, or other appliance, device, or structure that comprises a space to be temperature controlled. In some non-limiting embodiments, the first heat exchanger 11 may be referred to as an indoor heat exchanger or a conditioned space heat exchanger. Heat pump system 10, 10A also includes a second heat exchanger 12, which is in communication with an environment, which, without limitation, may be atmospheric air, or a geothermal region, a room, or some other region differing from the conditioned space, and may, in some non-limiting embodiments, be referred to as an outdoor heat exchanger or an environmental heat exchanger. When the conditioned space is to be cooled, the heat pump system 10, 10A operates to pump heat from the conditioned space to the environment. When the conditioned space is to be heated, the heat pump system 10, 10A operates to pump heat to the conditioned space from the environment. Heat pump system 10, 10A further includes a compressor 15. The heat pump system 10, 10A also includes a first expansion valve 21, a second expansion valve 22, a third expansion valve 23, and a four- way valve 24. The heat pump system 10, 10A also includes a thermal fluid, which may be any suitable liquid or gas used to transfer heat through the system. The thermal fluid may comprise a refrigerant chosen by one or ordinary skill in the art. Without limitation, a refrigerant may comprise a chlorofluorocarbon, a chlorofluoroolefin, a hydrochlorofluorocarbon, a hydrochlorofluoroolefin, a hydrofluorocarbon, a hydrofluoroolefin, a hydrochlorocarbon, a hydrochloroolefin, a hydrocarbon, a hydroolefin, a perfluorocarbon, a perfluoroolefin, a perchlorocarbon, a perchloroolefin, a halon, or combinations thereof. Without limitation, a refrigerant may comprise, R717, also known as ammonia, and having the formula NH₃; R744, also known as carbon dioxide, and having the formula C0₂; R12, also known as dichlorodifluoromethane, and having the formula CC1₂F₂; DME, also known as dimethyl ether, and having the formula CH₃OCH₃; R-124, also known as 1- Chloro-l,2,2,2-tetrafluoroethane, and having the formula C₂HC1F₄; Freon 142b, also known as 1- Chloro-l,l-difluoroethane, and having the formula CH₃CC1F₂; R-134a, also known as 1,1,1,2- Tetrafluoroethane, and having the formula CH₂FCF₃; HFO-1234yf, also known as 2,3,3,3- Tetrafluoropropene, and having the formula CH₂=CFCF₃; R-22 also known as chlorodifluoromethane, and having the formula CHC1F₂; R-410A, a mixture of difluoromethane, CH₂F₂, and pentafluoroethane, CHF₂CF₃; propane, having the formula C₃H₈; or combinations thereof. There are many other acceptable refrigerants which may be used. The present subject matter is not limited by refrigerant type.

[0014] Thermal fluid may comprise a liquid that changes phases as it undergoes compression or expansion in the system including, but not limited to, refrigerants such as R-134a and the like.

[0015] Compressor 15 includes a compressor discharge 16 and a compressor suction 17. The compressor discharge 16 is in communication with the four- way valve 24. The four- way valve 24, when in cooling mode (shown in Figs. 1 and 1A), provides communication between the compressor discharge 16 and second heat exchanger 12 allowing compressed and heated thermal fluid, generally indicated by the arrows, to enter second heat exchanger 12 at a first port 31. The thermal fluid flows through second heat exchanger 12 and exits at a second port outlet 32 that is in communication with second expansion valve 22 and third expansion valve 23. In the cooling mode shown in Figs. 1 and 1A, second expansion valve 22 is closed causing the thermal fluid exiting the second heat exchanger 12 to flow through third expansion valve 23. Third expansion valve 23 is in fluid communication with first expansion valve 21 and first heat exchanger 11. In the cooling mode shown in Figs. 1 and 1A, the first expansion valve 21 is closed causing the thermal fluid exiting third expansion valve 23 to flow into first heat exchanger 11 at first port 33. That is, in the cooling mode shown in Figs. 1 and 1A, the first expansion valve 21 is closed, the second expansion valve 22 is closed, and the third expansion valve 23 is open.

[0016] As the thermal fluid flows through the second heat exchanger 12, heat is released to the environment such that the thermal fluid exiting second heat exchanger 12 has less thermal energy; that is, is cooler. The cooled thermal fluid exiting the second heat exchanger 12 is further cooled as it flows through third expansion valve 23 and enters first heat exchanger 11. First heat exchanger 11 is, thus, used to cool the conditioned space S such as, without limitation, by cooling air provided to the conditioned space S. To facilitate this operation, in some non- limiting embodiments, a first fan 41 may be provided to direct air over the first heat exchanger 11 and into the conditioned space S. Ducting or vents may be provided to route air passing over first heat exchanger 11 to the conditioned space S in a devised manner. A second fan 42, likewise, may be provided to direct air over the second heat exchanger 12 to facilitate heat transfer from the second heat exchanger 12 to the environment. The thermal fluid exits first heat exchanger 11 at a second port 34. The second port 34 is in fluid communication with second valve 22 and four-way valve 24. As previously mentioned, in cooling mode, second valve 22 is closed such that the thermal fluid exiting first heat exchanger 11 is directed by four-way valve 24 to the compressor suction 17.

[0017] With reference to Figs. 2 and 2A, a heating mode for each of the heat pump systems 10 and 10A is shown. In the heating mode, four- way valve 24 is oriented such that thermal fluid exiting compressor 15 via compressor discharge 16 is directed toward first heat exchanger 11. As in the cooling mode, the first and second expansion valves 21, 22 are closed. Heated thermal fluid exiting the compressor 15 flows through first heat exchanger 11 to provide heat to the conditioned space. After providing heat to the conditioned space, the thermal fluid exits the first heat exchanger 11 and is directed through third expansion valve 23 further cooling the thermal fluid before it is directed to second heat exchanger 12. The cooled thermal fluid entering the second heat exchanger 12 is warmed by heat from the environment and exits second heat exchanger 12 to flow through four- way valve 24 to the compressor suction 17.

[0018] In some embodiments, a heat pump system 10, 10A may comprise a heat accumulator 50, 150 in thermal communication with the compressor 15. A first non-limiting embodiment of a heat accumulator 50 is shown in Figures 1, 2, and 3 and a second non-limiting embodiment of a heat accumulator 150 is shown in Figures 1A, 2A, and 3 A. The thermal communication between the heat accumulators 50, 150 and the compressor 15 is an adaptation that allows heat from operation of the compressor 15 which would otherwise be dismissed to the atmosphere and wasted, that is, waste heat, to be removed from the compressor 15 and stored in the heat accumulator 50, 150. [0019] In the non-limiting embodiment shown in Figures 1-3, heat accumulator 50 wraps around the housing 51 of compressor 15, may comprise a solid surface in direct thermal contact with the compressor housing 51, and may be adapted to absorb waste heat from the compressor primarily by conduction. Herein unless otherwise noted, transfer of heat primarily by a particular means indicates that the particular means is the primary heat transfer means, such that more heat is transferred by the particular means than by either of the other recognized heat transfer means. For example and without limitation, transfer of heat primarily by conduction indicates that conduction is the primary heat transfer means, such that more heat is transferred by conduction than by either of the other heat transfer means, convection or radiation. In the non- limiting embodiment shown in Figure 3, heat accumulator 50 has a surface 52 that contacts compressor housing 51. Surface 52 may conform to the housing 51 to maximize the contact with compressor 15. As shown in Figure 3, when a cylindrical compressor housing 51 is used, surface 52 may be concave to encompass a greater portion of compressor housing 51. As shown, surface 52 may define an arc matching an arc defined by the circular shape of housing 51. The accumulator body 53 may follow the arc of surface 52, as shown. As shown in Figure 3, body 53 of accumulator 50 include a semi-circular portion 54 that conforms to at least part of the outer surface of compressor 15 and an end portion 56 that extends at a tangent to compressor housing 51. The accumulator may include a body 53 which may be formed of a heat absorption material including but not limited to plastics, ceramics, oxidized metals, black chrome, or other materials with high absorption and/or low emissivity properties. In other embodiments, a heat accumulator may comprise a fluid mass, such as, without limitation, air, water, or oil, adapted to absorb waste heat from the compressor primarily by forced or natural convection. In other embodiments, a heat accumulator may be adapted to absorb waste heat from the compressor primarily by radiation.

[0020] As shown in Figure 3, a passage 55 may be provided at least partially within the body 53 to route a thermal fluid through body 53 of heat accumulator 50 to transfer heat accumulated within body 53 to the thermal fluid. Passage 55 may be integrally formed within body 53 and in this sense may simply be a passage within the body 53 or passage 55 may be a separate conduit or other structure placed in thermal contact with body 53 through which thermal fluid is routed. In the non-limiting example depicted in Figure 3, passage 55 is a conduit, which may be manufactured from a heat conductive material including, but not limited to, metals such as, for example, copper or aluminum. Passage 55 is located within the body 53 of heat accumulator 50. The passage 55 has two openings that each act as an inlet or outlet depending on the flow of thermal fluid through the passage 55. Passage 55 may extend throughout accumulator body 53 and may take a straight route through body 53 or include a non-straight path to increase the surface area of passage 55 within accumulator 50. For example, to form a non-straight path, passage 55 may include a number of turns that route the thermal fluid back and forth across the length and/or width of the heat accumulator body 53 such that passage 55 is a coil or otherwise convoluted. In the non-limiting embodiment shown in Figures 1-3, passage 55 is in thermal communication with the heat accumulator 50, is in fluid communication with the compressor 15, and is in selectable fluid communication with first heat exchanger 11 through valve 21.

[0021] As shown, passage 55 may be located within only a portion of heat accumulator 50. For example, passage 55 may be located generally in the portion of accumulator 50 in closest contact with compressor 15. In the example shown, passage 55 generally resides in the concave portion 54 of accumulator 50 with an inlet 57 located near one end of the semi-circular portion 54 and an exit 58 at the opposite end of semi-circular portion 54. In this example, passage 55 traces a somewhat semi-circular path and generally conforms to the shape of surface 52. In other embodiments, passage 55 may be located fully within heat accumulator 50.

[0022] In the non-limiting embodiment shown in Figures 1A-3A, heat accumulator 150 is in thermal communication with compressor 15 by a heat transfer conduit 171. Heat transfer conduit 171 may wrap around the housing 51 of compressor 15, may comprise a solid surface in direct thermal contact with the compressor housing 51, and may be adapted to absorb waste heat from the compressor primarily by conduction. Heat transfer conduit 171 may conform to the housing 51 to increase the contact with compressor 15. In other embodiments, the thermal engagement between heat transfer conduit 171 and the compressor 15 may entail indirect engagement with the compressor 15 or engagement with internal regions or components of the compressor 15. In the non-limiting embodiment shown in Figures 1A-3A, heat accumulator 150 defines a volume containing a thermal storage material 152. The accumulator 150 may include a body 153 formed of a heat absorption material including but not limited to plastics, ceramics, oxidized metals, black chrome, or other materials with high absorption and/or low emissivity properties. As noted above, in other embodiments, a heat accumulator 150 may comprise a fluid mass, such as, without limitation, air, water, or oil, adapted to absorb waste heat from the compressor primarily by forced or natural convection. In other embodiments, a heat accumulator 150 may be adapted to absorb waste heat from the compressor primarily by radiation.

[0023] As shown in Figures 1A-3A, a passage 155 may be provided at least partially within the body 153 to route a thermal fluid through body 153 of heat accumulator 150 to transfer heat accumulated from heat transfer conduit 171 to heat accumulator 150. Passage 155 may be integrally formed within body 153 and in this sense may simply be a passage within the body 153 or passage 155 may be a separate conduit or other structure placed in thermal contact with body 153 through which thermal fluid is routed. In the non-limiting example depicted in Figures 1A-3A, passage 155 is a conduit, which may be manufactured from a conductive material including, but not limited to, metals such as, without limitation, copper or aluminum. Passage 155 is located within the body 153 of heat accumulator 150.

[0024] The passage 155 forms part of a heat transfer loop between compressor 15 and the heat accumulator 150. The flow of thermal fluid through the passage 155 may be driven by a pump 173. Passage 155 may extend throughout body 153 and may take a straight route through body 153 or include a non-straight path to increase the surface area of passage 155 within accumulator 150. For example, to form a non-straight path, passage 155 may include a number of turns that route the thermal fluid back and forth across the length and/or width of the heat accumulator body 153 such that passage 155 is a coil or otherwise convoluted.

[0025] With reference to the embodiment shown Figure 1A-3A, heat accumulator 150 may contain a thermal reservoir material 152 suitable for storing heat. Exemplary thermal reservoir materials 152 include, but are not limited to, water, and a mixture of water and antifreeze or another additive. In the non-limiting embodiment shown in Figures 1A-3A, passage 159 is at least partially positioned with body 153 and provides a path to route a thermal fluid through the thermal reservoir material 152 of heat accumulator 150 to transfer heat accumulated therein to the thermal fluid. In the non-limiting embodiment shown in Figures 1A-3A, passage 159 is in thermal communication with the heat accumulator 150, is in fluid communication with the compressor 15, and is in selectable fluid communication with first heat exchanger 11 through valve 21.

[0026] With continued reference to the non-limiting embodiment shown Figure 3A, operation of the heat pump assembly 10A in a defrosting mode is shown. The heat pump assembly 10A may include two valves, such as, without limitation, valve 21 and valve 22, to separate the thermal fluid flow into two conjoined circuits during defrosting. In the non-limiting embodiment shown in Figure 3 A, the thermal fluid flow in the first circuit is conjoined with the thermal fluid flow in the second circuit. A continuous system is one in which all fluid paths, branches, or loops are conjoined in fluid communication with one another. As used herein "simultaneous" fluid flow refers to fluid flow that occurs at the same time or with a very slight deviation from occurring at exactly the same time. Very slight deviation from occurring at exactly the same, on the order of split second deviations, are acceptable and will be treated as simultaneous herein. In the non-limiting embodiment shown in Figure 3A, the thermal fluid flow in the first circuit may be conjoined with, and continuous with, the thermal fluid flow in the second circuit. In the non-limiting embodiment shown in Figure 3 A, the thermal fluid flow in the first circuit may be conjoined with, and simultaneous with, the thermal fluid flow in the second circuit. In the non-limiting embodiment shown in Figure 3 A, the thermal fluid flow in the first circuit may be conjoined with, and continuous with, and simultaneous with, the thermal fluid flow in the second circuit. In the non-limiting embodiment shown in Figure 3A, the two valves are first expansion valve 21 and second expansion valve 22. In other embodiments, other valves may be used in place of the expansion valves 21 and 22 including but not limited to other expansion devices, or capillary devices. In this defrosting mode of operation, the first expansion valve 21 and second expansion valve 22 are opened and the four- way valve 24 oriented such that compressed, heated thermal fluid exits from the compressor discharge 16 passes through four- way valve 24 toward first heat exchanger 11. With second expansion valve 22 open, a portion of the heated thermal fluid is directed into the second circuit, through second expansion valve 22 toward second heat exchanger 12. In the defrost mode, third expansion valve 23 is closed to divide the conduit into two circuits, one circuit for each heat exchanger. The heated fluid flowing through second expansion valve 22 enters second heat exchanger 12 to perform a defrosting operation and exits the second heated exchanger 12 in a cooled state. Meanwhile, a portion of the heated thermal fluid from compressor discharge 16 flows into the first circuit to first heat exchanger 11 and is used to heat the air provided to the conditioned space. In the defrost mode, the pump 173 may be in operation to circulate the thermal fluid in passage 155 to transfer heat from the compressor 15 to the heat accumulator 150. Thermal fluid exiting first heat exchanger 11 passes through first expansion valve 21 and is directed to the heat accumulator 150. The thermal fluid exiting first expansion valve 21 is relatively cool and is heated as it passes through passage 159 within heat accumulator 150. The relatively warm thermal fluid exiting accumulator 150 is routed toward the outlet of second heat exchanger 12 to mix with the thermal fluid exiting second heat exchanger 12 at a junction 60. Since the thermal fluid exiting second heat exchanger 12 performed a defrost function, it is relatively cool and the relatively warm fluid exiting the heat accumulator 150 heats the fluid exiting the second heat exchanger prior to its return to the compressor 15. As shown, the mixed fluid from the heat accumulator 150 and second heat exchanger 12 is routed through four-way valve 24 to the compressor suction 17. In the non-limiting embodiment shown in Figure 3 A, the flow in the second circuit bypasses, that is flows around rather than through, the first heat exchanger 11. In the non-limiting embodiment shown in Figure 3A, the flow in the second circuit bypasses the heat accumulator 150.

[0027] With reference to the embodiment shown Figure 1A, in the cooling mode, the pump 173 may be shut off such that the thermal fluid in passage 155 does not circulate to transfer heat from the compressor 15 to the heat accumulator 150. With reference to the embodiment shown Figure 2A, in the heating mode, the pump 173 may be in operation to circulate the thermal fluid in passage 155 to transfer heat from the compressor 15 to the heat accumulator 150.

[0028] With reference to the non-limiting embodiment shown Figure 3, operation of the heat pump assembly 10 in a defrosting mode is shown. The heat pump assembly 10 may include two valves, such as, without limitation, valve 21 and valve 22, to separate the thermal fluid flow into two conjoined circuits during defrosting. In the non-limiting embodiment shown in Figure 3, the thermal fluid flow in the first circuit may be conjoined with, and continuous with, the thermal fluid flow in the second circuit. In the non-limiting embodiment shown in Figure 3, the thermal fluid flow in the first circuit may be conjoined with, and simultaneous with, the thermal fluid flow in the second circuit. In the non-limiting embodiment shown in Figure 3, the thermal fluid flow in the first circuit may be conjoined with, and continuous with, and simultaneous with, the thermal fluid flow in the second circuit. In the non-limiting embodiments shown in Figure 3, the two valves are first expansion valve 21 and second expansion valve 22. In other embodiments, other valves may be used in place of the expansion valves 21 and 22 including but not limited to other expansion devices, or capillary devices. In this defrosting mode of operation, the first expansion valve 21 and second expansion valve 22 are opened and the four- way valve 24 oriented such that compressed, heated thermal fluid exits from the compressor discharge 16 passes through four- way valve 24 toward first heat exchanger 11. With second expansion valve

22 open, a portion of the heated thermal fluid is directed into the second circuit, through second expansion valve 22 toward second heat exchanger 12. In the defrost mode, third expansion valve

23 is closed to divide the conduit into two circuits, one circuit for each heat exchanger. The heated fluid flowing through second expansion valve 22 enters second heat exchanger 12 to perform a defrosting operation and exits the second heated exchanger 12 in a cooled state. Meanwhile, a portion of the heated thermal fluid from compressor discharge 16 flows into the first circuit to first heat exchanger 11 and is used to heat the air provided to the conditioned space. Thermal fluid exiting first heat exchanger 11 passes through first expansion valve 21 and is directed to the heat accumulator 50. The thermal fluid exiting first expansion valve 21 is relatively cool and is heated as it passes through the passage 55 within heat accumulator 50. The relatively warm thermal fluid exiting accumulator 50 is routed toward the outlet of second heat exchanger 12 to mix with the thermal fluid exiting second heat exchanger 12 at a junction 60. Since the thermal fluid exiting second heat exchanger 12 has performed a defrost function, it is relatively cool and the relatively warm fluid exiting the heat accumulator 50 heats the fluid exiting the second heat exchanger prior to its return to the compressor 15. As shown, the mixed fluid from the heat accumulator 50 and second heat exchanger 12 is routed through four- way valve 24 to the compressor suction 17. In the non-limiting embodiment shown in Figure 3, the flow in the second circuit bypasses, that is flows around rather than through, the first heat exchanger 11. In the non-limiting embodiment shown in Figure 3, the flow in the second circuit bypasses the heat accumulator 150.

[0029] It will be appreciated that, when using a thermal fluid that undergoes a phase change, thermal fluid exiting second heat exchanger 12 may be in the form of a low temperature mist and thermal fluid exiting heat accumulator 50 will be an over-heated thermal fluid gas such that when the two flows combine the low temperature mist is heated to a gas state avoiding any liquid pressure within the compressor suction 17.

[0030] In the example shown, the conduits, junctions, and valves are shown schematically and any suitable conduit junction, or valve may be used in accordance with the description above. Optionally, to segregate the heat accumulator passage 55, 159 during heating and cooling operations, an accumulator valve may be provided at the heat accumulator conduit upstream of the junction 60 where the heat accumulator outlet merges with the conduit extending from first port 31 of second heat exchanger 12.

[0031] The present invention may be embodied in other forms without departing from the spirit and the essential attributes thereof, and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification, as indicating the scope of the invention.

Claims

WHAT IS CLAIMED:

1. A heat pump system for a conditioned space comprising:

a first thermal fluid circuit adapted to selectably operate to circulate a thermal fluid therein, the first thermal fluid circuit comprising a compressor, a first heat exchanger, and a passage of a heat accumulator; and

a second thermal fluid circuit adapted to selectably operate to circulate the thermal fluid therein, the second thermal fluid circuit

bypassing the first heat exchanger and the passage of the heat accumulator, and

comprising the compressor, and a second heat exchanger.

2. The heat pump system of claim 1, wherein the thermal fluid is a refrigerant.

3. The heat pump system of claim 2, wherein the passage of the heat accumulator is at least partially within the heat accumulator.

4. The heat pump system of claim 3, wherein the first thermal fluid circuit and the second thermal fluid circuit are conjoined to form a continuous system.

5. The heat pump system of claim 3, wherein the system is adapted to be operable to flow the thermal fluid through the first thermal fluid circuit and to simultaneously flow the thermal fluid through the second thermal fluid circuit.

6. The heat pump system of claim 4, wherein the system is adapted to be operable to flow the thermal fluid through the first thermal fluid circuit and to simultaneously flow the thermal fluid through the second thermal fluid circuit.

7. The heat pump system of claim 6, wherein the heat accumulator comprises a solid surface in direct thermal contact with the compressor.

8. The heat pump system of claim 7, wherein the heat accumulator is adapted to transfer heat from the compressor primarily by conduction.

9. The heat pump system of claim 6, wherein the heat accumulator is in thermal communication with the compressor through a heat transfer conduit.

10. The heat pump system of claim 6, wherein the heat transfer conduit comprises a solid surface in direct thermal contact with the compressor.

11. A method of defrosting a part of a heat pump system for a conditioned space comprising: providing a heat pump system for a conditioned space comprising,

bypassing the first heat exchanger and the passage of the heat accumulator, and

comprising the compressor, and a second heat exchanger;

operating the system,

to circulate the thermal fluid in first thermal fluid circuit, and

to circulate the thermal fluid in the second thermal fluid circuit.

12. The method of defrosting a part of a heat pump system for a conditioned space of claim 11 , wherein the thermal fluid is a refrigerant.

13. The method of defrosting a part of a heat pump system for a conditioned space of claim

12, wherein the passage of the heat accumulator is at least partially within the heat accumulator.

14. The method of defrosting a part of a heat pump system for a conditioned space of claim

13, wherein the first thermal fluid circuit and the second thermal fluid circuit are conjoined to form a continuous system.

15. The method of defrosting a part of a heat pump system for a conditioned space of claim

13, wherein the system is adapted to be operable to flow the thermal fluid through the first thermal fluid circuit and to simultaneously flow the thermal fluid through the second thermal fluid circuit.

16. The method of defrosting a part of a heat pump system for a conditioned space of claim

14, wherein the system is adapted to be operable to flow the thermal fluid through the first thermal fluid circuit and to simultaneously flow the thermal fluid through the second thermal fluid circuit.

17. The method of defrosting a part of a heat pump system for a conditioned space of claim 16, wherein the heat accumulator is adapted to transfer heat from the compressor primarily by conduction.

18. The method of defrosting a part of a heat pump system for a conditioned space of claim 16, wherein the heat accumulator is in thermal communication with the compressor through a heat transfer conduit.

19. The method of defrosting a part of a heat pump system for a conditioned space of claim 16, wherein the heat transfer conduit comprises a solid surface in direct thermal contact with the compressor.

20. A heat pump system for a conditioned space comprising: a first thermal fluid circuit adapted to selectably operate to circulate a thermal fluid therein, the first thermal fluid circuit,

comprising a compressor, a first heat exchanger, and a passage of a heat accumulator,

wherein the thermal fluid is a refrigerant

wherein the heat accumulator

a) comprises a solid surface in direct thermal contact with the compressor, and is adapted to transfer heat from the compressor primarily by conduction, or

b) is in thermal communication with the compressor through a heat transfer conduit comprising a solid surface in direct thermal contact with the compressor,

wherein the passage is at least partially within the heat accumulator;

a second thermal fluid circuit adapted to selectably operate to circulate the thermal fluid therein, the second thermal fluid circuit,

bypassing the first heat exchanger and the passage of the heat accumulator, and comprising the compressor, and a second heat exchanger;

wherein the first thermal fluid circuit and the second thermal fluid circuit are conjoined to form a continuous system; and

wherein the system is adapted to be operable to flow the thermal fluid through the first thermal fluid circuit and to simultaneously flow the thermal fluid through the second thermal fluid circuit.