Heat pump apparatus

Abstract

A heat pump apparatus includes a heat source unit including a first refrigerant circuit in which refrigerant circulates, and a first heat medium heat exchanger, a relay unit, and including a second refrigerant circuit, and including a second heat medium heat exchanger, a first load device including a first load-side heat exchanger, a second load device including a second load-side heat exchanger, a first heat medium circuit in which the first heat medium heat exchanger and the first load-side heat exchanger are connected by an outbound heat medium pipe and a return heat medium pipe, and in which heat medium circulates, a second heat medium circuit in which the second heat medium heat exchanger and the second load-side heat exchanger are connected by a heat medium pipe, and in which a heat medium circulates.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a heat pump apparatus.BACKGROUND ART

[0002] Traditionally, various heat pump apparatuses utilizing refrigerant and heat mediums have been disclosed (see, for example, Patent Literature 1). For instance, Patent Literature 1 discloses a cold-and-hot water multi-air conditioning device that includes two cold-and-hot water devices and a plurality of indoor units installed on each floor of a building. In this cold-and-hot water multi-air conditioning device, each outdoor unit is connected to a plurality of indoor units by cold-and-hot water pipes. An outdoor unit of one of the cold-and-hot water multi-air conditioning device is used for cooling operation, and an outdoor unit of the other of the cold-and-hot water multi-air conditioning device is used for heating operation, enabling simultaneous cooling and heating operation in each indoor unit.CITATION LISTPatent Literature

[0003] Patent Literature 1: JPH04-214134ASUMMARY OF INVENTIONTechnical Problem

[0004] However, in the cold-and-hot water multi-air conditioning device of Patent Literature 1, two cold-and-hot water pipes for circulating cold water connected to the outdoor unit of one of the cold-and-hot water multi-air conditioning devices, and two cold-and-hot water pipes for circulating hot water connected to the outdoor unit of the other of the cold-and-hot water multi-air conditioning devices, are required. Therefore, it is necessary to install two cold-and-hot water pipes to each outdoor unit placed outside, and due to the large number of cold-and-hot water pipes to be installed, the cost of piping becomes high and the burden of pipe construction increases, posing a problem of poor constructability.

[0005] The heat pump apparatus of the present disclosure is made to overcome the above-mentioned problems, and an object thereof is to provide a heat pump apparatus that reduces pipe costs and improves constructability by reducing the number of heat medium pipes connected to the heat source unit.Solution to Problem

[0006] A heat pump apparatus according to an embodiment of the present disclosure includes a heat source unit including a first refrigerant circuit configured to switch between cooling operation and heating operation, and in which refrigerant circulates, and a first heat medium heat exchanger configured to conduct heat exchange with the first refrigerant circuit, a relay unit including a second refrigerant circuit configured to switch between cooling operation and heating operation and in which refrigerant circulates, and a second heat medium heat exchanger configured to conduct heat exchange with the second refrigerant circuit, a first load device including a first load-side heat exchanger, a second load device including a second load-side heat exchanger, a first heat medium circuit in which the first heat medium heat exchanger and the first load-side heat exchanger are connected by an outbound heat medium pipe and a return heat medium pipe, and in which heat medium circulates, a second heat medium circuit in which the second heat medium heat exchanger and the second load-side heat exchanger are connected by a heat medium pipe, and in which a heat medium circulates.Advantageous Effects of Invention

[0007] According to an embodiment of the heat pump apparatus of the present disclosure, when cooling and heating operation is simultaneously performed at a plurality of load devices, either cooling or heating can be performed with the first refrigerant circuit in the heat source unit and the second refrigerant circuit in the relay unit for each operation. Therefore, the number of heat medium pipes connected to the heat source unit can be limited to two, namely, the outbound heat medium pipe and the return heat medium pipe. As a result, compared to traditional systems, the number of pipes connected to the heat source unit can be reduced, thereby lowering the pipe costs and reducing the burden of pipe construction. This, in turn, improves the ease of construction.BRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. 1 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus according to Embodiment 1.

[0009] FIG. 2 is a refrigerant circuit diagram that shows the flows of the refrigerant and the heat medium when the heat pump apparatus according to Embodiment 1 performs cooling only operation.

[0010] FIG. 3 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when heating only operation is performed in the heat pump apparatus according to Embodiment 1.

[0011] FIG. 4 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when cooling main operation is performed in the heat pump apparatus according to Embodiment 1.

[0012] FIG. 5 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when heating main operation is performed in the heat pump apparatus according to Embodiment 1.

[0013] FIG. 6 is a refrigerant circuit diagram showing an example of the circuit configuration of the heat pump apparatus according to Embodiment 2.DESCRIPTION OF EMBODIMENTS

[0014] Hereinafter, the embodiments of the present disclosure will be explained based on the drawings. However, the present disclosure is not limited to the embodiments described below. Furthermore, in the following drawings, the dimensional relationships of components may differ from those of the actual ones.Embodiment 1

[0015] FIG. 1 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100 according to Embodiment 1. As shown in FIG. 1, the heat pump apparatus 100 according to Embodiment 1 includes a heat source unit 10, a plurality of load devices (four in Embodiment 1), a relay unit 30, and a controller 40. Among the four load devices, three are first load devices 20Aa, 20Ab, and 20Ac for switching between cooling and heating operations, performing the same operation as each other. One is a second load device 20B for simultaneous cooling and heating operations, which performs the same or different operations as the first load devices 20Aa, 20Ab, and 20Ac. The heat pump apparatus 100 has a structure in which the heat source unit 10 and the three first load devices 20Aa, 20Ab, 20Ac are connected via two heat medium pipes (an outbound heat medium pipe 5a and return heat medium pipe 5b). Additionally, the three first load devices 20Aa, 20Ab, and 20Ac are connected in parallel to the heat source unit 10. Even though FIG. 1 shows three first load devices 20Aa, 20Ab, 20Ac, the number of the load devices is not limited to three, and could be any number as long as it's one or more. The heat source unit 10 is an outdoor unit, for example. The first load devices 20Aa, 20Ab, 20Ac and the second load device 20B are indoor units, as an example. The heat source unit 10 is installed, for instance, on the roof of a building. The relay unit 30, the first load devices 20Aa, 20Ab,20Ac, and the second load device 20B are installed inside the building, for instance. The heat source unit 10, the first load devices 20Aa, 20Ab, 20Ac, the second load device 20B, and the relay unit 30 are controlled by the controller 40.

[0016] In addition, the heat pump apparatus 100 comprises a first refrigerant circuit 1 and a second refrigerant circuit 2 in which refrigerant circulates, as well as a first heat medium circuit 3 and a second heat medium circuit 4 in which a heat medium circulates. The first refrigerant circuit 1, for example, has a structure in which a first compressor 11, a first flow switching device 12, a heat source-side heat exchanger 13, a first expansion device 15, a first heat medium heat exchanger 16, and an accumulator 17 are cyclically connected in this order via a refrigerant pipe. The second refrigerant circuit 2, for example, has a structure in which a second compressor 31, a second flow switching device 32, a third heat medium heat exchanger 33, a second expansion device 34, and a second heat medium heat exchanger 35 are cyclically connected in this order via a refrigerant pipe. The first heat medium circuit 3, for example, has a structure in which a first pump 18, the first heat medium heat exchanger 16, the third heat medium heat exchanger 33, and the first load devices 20Aa, 20Ab, 20Ac are cyclically connected in this order via an outbound heat medium pipe 5a and a return heat medium pipe 5b. The second heat medium circuit 4, for example, has a structure in which a second pump 36, the second heat medium heat exchanger 35, and the second load device 20B are cyclically connected in this order via a heat medium pipe. In Embodiment 1, the first refrigerant circuit 1 is installed in the heat source unit 10, while the second refrigerant circuit 2 is installed in the relay unit 30.

[0017] The refrigerant filled into the first refrigerant circuit 1 and the second refrigerant circuit 2 can be, for example, a single-component refrigerant such as R1234yf, R1234ze, R32, and R290, or a mixed refrigerant of two or more of these, or a mixed refrigerant of any of these with another refrigerant, a mixed refrigerant including R1132(E), or a mixed refrigerant including R1123. Additionally, mixed refrigerants such as R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, and R459A can be utilized. The refrigerant filled into the first refrigerant circuit 1 and the refrigerant filled into the second refrigerant circuit 2 may be the same or different.

[0018] Examples of the heat medium filled in the first heat medium circuit 3 and the second heat medium circuit 4 include, for instance, water and brine. Additionally, the heat medium filled in the first heat medium circuit 3 and the heat medium filled in the second heat medium circuit 4 may be the same or different.Heat Source Unit 10

[0019] The heat source unit 10 comprises the first compressor 11, the first flow switching device 12, the heat source-side heat exchanger 13, the heat source-side fan 14, the first expansion device 15, the first heat medium heat exchanger 16, the accumulator 17, the first pump 18, and an opening-and-closing valve 19. The first compressor 11 suctions and compresses the refrigerant into a high-temperature, high-pressure state. The first compressor 11 comprises a capacity-controllable inverter compressor, for example. The first compressor 11 utilized may be of a low-pressure shell-structure type. The compressor with a low-pressure shell structure has a compression chamber within a sealed container, which creates a low refrigerant pressure atmosphere. It suctions and compresses the low-pressure refrigerant within the sealed container. The first flow switching device 12 is a four-way valve for example, and can switch between cooling and heating operation by redirecting the flow of the refrigerant. The first flow switching device could also be formed using a combination of two-way and three-way valves as an alternative to the four-way valve. The heat source-side heat exchanger 13 can serve as an evaporator or condenser, conducting heat exchange between the air and the refrigerant to evaporate and gasify or condense and liquefy the refrigerant. The heat source-side heat exchanger 13 serves as an evaporator during the heating operation and as a condenser during the cooling operation. The heat source-side fan 14 is installed near the heat source-side heat exchanger 13, and supplies air to the heat source-side heat exchanger 13. The first expansion device 15 depressurizes and expands the refrigerant. The first expansion valve may be an electronic expansion valve, for example, capable of adjusting the opening degree. By adjusting the opening degree, it regulates the pressure of the refrigerant flowing into the heat source-side heat exchanger 13 during the heating operation, and the pressure of the refrigerant flowing into the first heat medium heat exchanger 16 during the cooling operation. The first heat medium heat exchanger 16 has a heat transfer portion for passing refrigerant and another heat transfer portion for passing a heat medium, conducting heat exchange between the refrigerant and the heat medium. During heating operation, the first heat medium heat exchanger 16 serves as a condenser, allowing the refrigerant to heat the heat medium by radiating heat from the refrigerant. On the other hand, during the cooling operation, the first heat medium heat exchanger to serve as an evaporator, allowing the refrigerant to cool the heat medium by absorbing heat. The accumulator 17, located on the suction side of the first compressor 11, stores excess refrigerant generating due to the difference in necessary refrigerant quantity between heating and cooling operations, or transient operation changes. The first pump 18 is a heat medium sending device that pumps the heat medium to circulate in the second heat medium circuit 4. By varying the rotation speed of its built-in motor (not shown), the first pump can adjust the discharge flow volume of heat medium pumped out. Constructed as a two-way valve, for instance, the opening-and-closing valve 19 can control the passage of heat medium by its opening and closing.First Load Devices 20Aa, 20Ab, 20Ac

[0020] The first load devices 20Aa, 20Ab, and 20Ac each serve to supply heat from the heat source unit 10 for the cooling load or heating load, and to perform air conditioning or heating for the air-conditioning target space. The first load device 20Aa includes a first load-side heat exchanger 21Aa and a first load-side fan 22Aa. The first load device 20Ab includes a first load-side heat exchanger 21Ab and a first load-side fan 22Ab. The first load device 20Ac includes a first load-side heat exchanger 21Ac and a first load-side fan 22Ac.

[0021] In the following explanation, when there is no particular need to distinguish between the first load device 20Aa, the first load device 20Ab, and the first load device 20Ac, they will simply be referred to as “the first load device 20A” as appropriate. Additionally, the first load-side heat exchanger 21Aa, the first load-side heat exchanger 21Ab, and the first load-side heat exchanger 21Ac have the same configuration, and the first load-side fan 22Aa, the first load-side fan 22Ab, the and the first load-side fan 22Ac also have the same configuration. Therefore, the following explanation will use the first load-side heat exchanger 21Aa and the first load-side fan 22Aa as examples.

[0022] The first load-side heat exchanger 21Aa conducts heat exchange between indoor air and the heat medium. Specifically, during a cooling operation, the first load-side heat exchanger 21Aa cools the indoor air by allowing the heat medium to absorb heat. Additionally, during a heating operation, the first load-side heat exchanger 21Aa heats the indoor air by allowing the heat medium to reject heat. Note that the first load-side heat exchanger 21Aa is installed to have indoor air blown by the first load-side fan 22Aa installed nearby.Second Load Device 20B

[0023] The second load device 20B supplies heat from the relay unit 30 to the cooling load or the heating load, performing either cooling operation or heating operation for the air-conditioning target space. The second load device 20B includes a second load-side heat exchanger 21B and a second load-side fan 22B.

[0024] The second load-side heat exchanger 21B conducts heat exchange between the indoor air and the heat medium. Specifically, during a cooling operation, the second load-side heat exchanger 21B cools the indoor air by allowing the heat medium to absorb heat. Additionally, during a heating operation, the second load-side heat exchanger 21B heats the indoor air by allowing the heat medium to reject heat. Note that the second load-side heat exchanger 21B is installed to have indoor air blown by the second load-side fan 22B installed nearby.Relay Unit 30

[0025] The relay unit 30 includes the second compressor 31, the second flow switching device 32, the third heat medium heat exchanger 33, the second expansion device 34, the second heat medium heat exchanger 35, and the second pump 36. The second compressor 31 suctions and compresses the refrigerant, putting it under a high-temperature, high-pressure state. The second compressor 31 may be a capacity-controllable inverter compressor, for example. The second compressor 31, for example, can be of a low-pressure shell structure. The compressor with a low-pressure shell structure has a compression chamber within a sealed container, which creates a low refrigerant pressure atmosphere. It suctions and compresses the low-pressure refrigerant within the sealed container. The second flow switching device 32, which is, for example, a four-way valve, configured to switch between cooling operation and heating operation by changing the direction of the refrigerant flow. Instead of a four-way valve, a combination of a two-way and a three-way valve can also be used for the second flow switching device 32. The third heat medium heat exchanger 33 has a heat transfer portion for passing refrigerant and another heat transfer portion for passing a heat medium, conducting heat exchange between the refrigerant and the heat medium. The third heat medium heat exchanger 33 serves as a condenser during cooling operation, causing the refrigerant to reject heat to heat the heat medium. On the other hand, the third heat medium heat exchanger 33 serves as an evaporator during heating operation, causing the refrigerant to absorb heat to cool the heat medium. The second expansion device 34 depressurizes and expands the refrigerant. The second expansion device 34 is, for example, an electronic expansion valve with adjustable opening degree, and by adjusting the opening degree thereof, it controls the pressure of refrigerant flowing into the third heat medium heat exchanger 33 during heating operation and the pressure of refrigerant flowing into the second heat medium heat exchanger 35 during cooling operation. The second heat medium heat exchanger 35 has a heat transfer portion for passing refrigerant and another heat transfer portion for passing a heat medium, conducting heat exchange between the refrigerant and the heat medium. The second heat medium heat exchanger 35 serves as a condenser during heating operation by causing the refrigerant to reject heat to the heat medium and heat the heat medium, while it serves as an evaporator during cooling operation by causing the refrigerant to absorb heat from the heat medium to cool the heat medium. The second pump 36 is a heat medium sending device that pumps the heat medium to circulate it in the first heat medium circuit 3. The second pump 36 can vary the discharge flow rate, which is the volume of the heat medium being pumped out, by changing the rotation speed of its built-in motor (not shown in the figure) within a certain range.Controller 40

[0026] The controller 40 controls the entire heat pump apparatus 100. For example, depending on the operating actions of the heat pump apparatus 100, the controller 40 controls the first refrigerant circuit 1, the second refrigerant circuit 2, the first heat medium circuit 3, and the second heat medium circuit 4. The various functions of the controller 40 are achieved by executing software on computing devices like microcomputers, or it may be comprised of hardware such as circuit devices that implement various functions.

[0027] Next, the operational behaviors during various operations that the heat pump apparatus 100 performs are described. The operations of the heat pump apparatus100 include four types: cooling only operation, heating only operation, cooling main operation, and heating main operation.

[0028] “Cooling only operation” refers to an operational mode in which only cooling operation is possible in the first load device 20A and the second load device 20B, signifying the state in which the first load device 20A and the second load device 20B are performing cooling operation. “Heating only operation” refers to an operational mode in which only heating operation is possible at the first load device 20A and the second load device 20B, signifying the state in which the first load device 20A and the second load device 20B are performing heating operation. “Cooling main operation” refers to an operational mode in which the cooling load surpasses the heating load under simultaneous cooling and heating operation in which the first load device 20A performs cooling operation and the second load device 20B performs heating operation. “Heating main operation” refers to an operational mode in which the heating load surpasses the cooling load under simultaneous cooling and heating operation in which the first load device 20A performs heating operation and the second load device 20B performs cooling operation.Cooling Only Operation

[0029] Firstly, with reference to FIG. 2, the cooling only operation of the heat pump apparatus 100 is explained. FIG. 2 is a refrigerant circuit diagram that shows the flows of the refrigerant and the heat medium when the heat pump apparatus according to Embodiment 1 performs cooling only operation. Moreover, the solid arrows shown in FIG. 2 indicate the flow of the refrigerant, while the hollow arrows indicate the flow of the heat medium.

[0030] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant discharged from the first compressor 11 passes through the first flow switching device 12 to the heat source-side heat exchanger 13, where it conducts heat exchange with outdoor air to condense and liquefy. The condensed and liquefied refrigerant is depressurized by the first expansion device 15, becoming a low-pressure two-phase gas-liquid refrigerant, and flows into the first heat medium heat exchanger 16, where it exchanges heat with the heat medium flowing in the first heat medium circuit 3 to evaporate and gasify. The evaporated and gasified refrigerant passes through the first flow switching device 12, and is suctioned again into the first compressor 11 via the accumulator 17.

[0031] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 and to the third heat medium heat exchanger 33, where exchanges heat exchange with the heat medium flowing in the first heat medium circuit 3 to condense and liquefy. The condensed, liquefied refrigerant is depressurized in the second expansion device 34, becoming a low-pressure two-phase gas-liquid refrigerant, and flows into the second heat medium heat exchanger 35, where it exchanges heat with the heat medium flowing in the second heat medium circuit 4 to evaporate and gasify. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is suctioned back into the second compressor 31.

[0032] In the first heat medium circuit 3, the heat medium, pumped out by the first pump 18, is cooled by the refrigerant flowing through the first heat medium heat exchanger 16 and becomes cold water. The heat medium then flows into the first load-side heat exchangers 21Aa, 21Ab, and 21Ac, where it undergoes a heat exchange with the indoor air in the room, and is heated, while the indoor air is cooled in the process. The heated heat medium then flows into the third heat medium heat exchanger 33, where it is further heated by exchanging heat with the refrigerant flowing through the second refrigerant circuit 2. The heated heat medium is then suctioned back into the first pump 18 again.

[0033] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 is cooled by the refrigerant that flows through the second heat medium heat exchanger 35, becoming cold water. The heat medium then flows into the second load-side heat exchanger 21B, where it exchanges heat with indoor air in the indoor space, to be heated while cooling the indoor air. The heated heat medium is then suctioned back in by the second pump 36.Heating Only Operation

[0034] The following describes the heating only operation of the heat pump apparatus 100 with reference to FIG. 3. FIG. 3 is a refrigerant circuit diagram showing the flows of refrigerant and the heat medium when the heat pump apparatus 100, according to embodiment 1, performs a heating only operation. Note that the solid arrows shown in FIG. 3 indicate the flow of refrigerant, and the hollow arrow indicates the flow of the heat medium.

[0035] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant discharged from the first compressor 11 passes through the first flow switching device 12 and flows into the first heat medium heat exchanger 16. The refrigerant flowing into the first heat medium heat exchanger 16 exchanges heat with the heat medium flowing through the first heat medium circuit 3 to condense and liquefy, and is depressurized by the first expansion device 15, becoming a low-pressure, two-phase gas-liquid refrigerant that then flows to the heat source-side heat exchanger 13. The two-phase gas-liquid refrigerant flowing into the heat source-side heat exchanger 13 exchanges heat with the outside air to evaporate and gasify, then it passes through the first flow switching device 12 and is suctioned into the first compressor 11 via the accumulator 17.

[0036] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 and flows into the second heat medium heat exchanger 35 where it exchanges heat with the heat medium flowing in the second heat medium circuit 4 to condense and liquefy. The condensed and liquefied refrigerant is depressurized by the second expansion device 34, becoming a low-pressure, two-phase gas-liquid refrigerant, and then flows into the third heat medium heat exchanger 33 where it exchanges heat with the heat medium flowing through the first heat medium circuit 3 to evaporate and gasify. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is again suctioned into the second compressor 31.

[0037] In the first heat medium circuit 3, the heat medium pumped out by the first pump 18 becomes hot water after being heated by the refrigerant flowing through the first heat medium heat exchanger 16. It then flows into the first load-side heat exchangers 21Aa, 21Ab, 21Ac, where it exchanges heat with indoor air, to be cooled and heating the indoor air. The cooled heat medium flows into the third heat medium heat exchanger 33 and exchanges heat with the refrigerant flowing in the second refrigerant circuit 2, to be cooled. The cooled heat medium is then suctioned back into the first pump 18.

[0038] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 becomes hot water after being heated by the refrigerant flowing through the second heat medium heat exchanger 35. This hot water flows into the second load-side heat exchanger 21B, where it exchanges heat with the indoor air in the room and is cooled, while heating the indoor air. The cooled heat medium is suctioned again by the second pump 36,Cooling Main Operation

[0039] The following describes, with reference to FIG. 4, the case where cooling operation is performed by the first load device 20A, heating operation is performed by the second load device 20B, and a cooling main operation with a large cooling load is performed. FIG. 4 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when the cooling main operation is performed in the heat pump apparatus 100 according to Embodiment 1. Note that the solid arrows shown in FIG. 4 indicates the flow of refrigerant, and the hollow arrows represent the flow of the heat medium.

[0040] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant that is discharged from the first compressor 11 passes through the first flow switching device 12 and flows into the heat source-side heat exchanger 13, where it exchanges heat with the outdoor air to condense and liquefy. The condensed and liquefied refrigerant is depressurized by the first expansion device 15 and becomes a low-pressure two-phase gas-liquid refrigerant, which then flows into the first heat medium heat exchanger 16 and exchanges heat with the heat medium flowing through the first heat medium circuit 3 to be evaporated and gasified. The evaporated and gasified refrigerant passes through the first flow switching device 12, and is suctioned again into the first compressor 11 via the accumulator 17.

[0041] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 to the second heat medium heat exchanger 35, where it exchanges heat with the heat medium flowing in the second heat medium circuit 4, to be condensed and liquefied. The condensed and liquefied refrigerant is then depressurized by the second expansion device 34, becoming a low-pressure, two-phase gas-liquid refrigerant, which flows into the third heat medium heat exchanger 33. There, it exchanges heat with the heat medium flowing through the first heat medium circuit 3, to be evaporated and gasified. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is suctioned back into the second compressor 31.

[0042] In the first heat medium circuit 3, the heat medium pumped out by the first pump 18 is cooled by the refrigerant flowing through the first heat medium heat exchanger 16, turning it into cold water. This cold water then flows into the first load-side heat exchangers 21Aa, 21Ab, and 21Ac, where it exchanges heat with the indoor air in the room, being heated while cooling the air. The heated heat medium then flows into the third heat medium heat exchanger 33, where it exchanges heat with the refrigerant flowing through the second refrigerant circuit 2, to be cooled. The cooled heat medium is then suctioned back into the first pump 18.

[0043] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 is heated by the refrigerant flowing through the second heat medium heat exchanger 35, becoming hot water. This hot water then flows into the second load-side heat exchanger 21B where it exchanges heat with the indoor air within the indoor space, to be cooled while heating the indoor air. The cooled heat medium is then suctioned back into the second pump 36.Heating Main Operation

[0044] The following describes, with reference to FIG. 5, the case where heating operation is performed by the first load device 20A, and cooling operation is performed by the second load device 20B, and the explanation follows of the case where the heating operation, which has a high load, known as heating main operation is performed. FIG. 5 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when the heating main operation is performed in the heat pump apparatus 100 according to Embodiment 1. The solid arrows shown in FIG. 5 indicate the flow of the refrigerant, while the hollow arrows indicate the flow of the heat medium.

[0045] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant discharged from the first compressor 11 passes through the first flow switching device 12 and flows into the first heat medium heat exchanger 16. The refrigerant flowing into the first heat medium heat exchanger 16 exchanges heat with the heat medium flowing through the first heat medium circuit 3, to be condensed and liquefied. Then the condensed and liquefied refrigerant is depressurized by the first expansion device 15 to become a low-pressure, two-phase gas-liquid refrigerant, which flows into the heat source-side heat exchanger 13. The two-phase gas-liquid refrigerant flowing into the heat source-side heat exchanger 13 exchanges heat with outdoor air to be evaporated and gasified, then passes through the first flow switching device 12 and is suctioned into the first compressor 11 via the accumulator 17.

[0046] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 and flows into the third heat medium heat exchanger 33. Here, the high-temperature, high-pressure gas refrigerant exchanges heat with the heat medium flowing through the first heat medium circuit 3, to be condensed and liquefied. The condensed and liquefied refrigerant is depressurized by the second expansion device 34, becoming a low-pressure two-phase gas-liquid refrigerant. The low-pressure two-phase gas-liquid refrigerant then flows into the second heat medium heat exchanger 35 and exchanges heat with the heat medium flowing through the second heat medium circuit 4, to be evaporated and gasified. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is once again suctioned into the second compressor 31.

[0047] In the first heat medium circuit 3, the heat medium pumped out by the first pump 18 is heated by the refrigerant flowing through the first heat medium heat exchanger 16, becoming hot water. This hot water then passes through the first load-side heat exchangers 21Aa, 21Ab, 21Ac, where it exchanges heat with indoor air in the room, being cooled in the process while heating the indoor air. The cooled heat medium then flows into the third heat medium heat exchanger 33, where it is heated by exchanging heat with the refrigerant flowing through the second refrigerant circuit 2. The heated heat medium is then suctioned back into the first pump 18.

[0048] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 is cooled by the refrigerant flowing through the second heat medium heat exchanger 35, becoming cold water. Then, it flows into the second load-side heat exchanger 21B where it exchanges heat with the indoor air in the room to be heated while the indoor air is cooled. The heated heat medium is again suctioned into the second pump 36.

[0049] From the above, with the heat pump apparatus 100 according to Embodiment 1, when both the cooling operation and the heating operating is simultaneously performed with a plurality of load devices, a first refrigerant circuit 1, provided at the heat source unit 10, and a second refrigerant circuit 2, provided at the relay unit 30, can carry out either cooling operation or heating operation individually. Therefore, the number of heat medium pipes connected to the heat source unit 10 can be reduced to two, namely, the outbound heat medium pipe 5a and return heat medium pipe 5b. Consequently, this reduction in the number of pipes connected to the heat source unit 10 over the conventional systems can lower pipe costs, reduce the burden of pipe construction, and improve the ease of construction.

[0050] As described above, the heat pump apparatus 100 according to Embodiment 1 includes the heat source unit 10, which has the first refrigerant circuit 1 in which refrigerant circulates, and which is capable of switching between the cooling operation and the heating operation, and the first heat medium heat exchanger 16 that exchanges heat with the first refrigerant circuit 1. The heat pump apparatus 100 also includes the relay unit 30 that includes the second refrigerant circuit 2 which is capable of switching between the cooling operation and the heating operation and in which refrigerant circulates, and the second heat medium heat exchanger 35 that exchanges heat with the second refrigerant circuit 2. The heat pump apparatus 100 also includes a first load devices 20Aa, 20Ab, and 20Ac that have first load-side heat exchangers 21Aa, 21Ab, and 21Ac, and a second load device 20B that includes a second load-side heat exchanger 21B. The heat pump apparatus 100 also includes a first heat medium circuit 3 in which a heat medium circulates and in which the first heat medium heat exchanger 16 and the first load-side heat exchangers 21Aa, 21Ab, and 21Ac are connected by the outbound heat medium pipe 5a and a return heat medium pipe 5b. The heat pump apparatus 100 also includes a second heat medium circuit 4, and the second heat medium heat exchanger 35 and the second load-side heat exchanger 21B are connected by a heat medium pipe in which a heat medium circulates.

[0051] According to Embodiment 1 of the heat pump apparatus 100, when the cooling operation and the heating operation are simultaneously performed at a plurality of load devices, either the cooling operation or the heating operation can be performed with the first refrigerant circuit 1 in the heat source unit 10 and the second refrigerant circuit 2 in the relay unit 30 for each operation. Therefore, the number of heat medium pipes connected to the heat source unit 10 can be limited to two, namely, the outbound heat medium pipe 5a and the return heat medium pipe 5b. As a result, compared to traditional systems, the number of pipes connected to the heat source unit 10 can be reduced, thereby lowering the pipe costs and reducing the burden of pipe construction. This, in turn, improves the ease of construction.Embodiment 2

[0052] The following describes Embodiment 2. Explanations are omitted for parts that overlap with Embodiment 1 and the same reference numerals are assigned to parts that are the same as or equivalent to those of Embodiment 1.

[0053] FIG. 6 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100A according to Embodiment 2. In the heat pump apparatus 100A according to Embodiment 2, as shown in FIG. 6, there is no relay unit 30, and in addition to the second refrigerant circuit 2, the second heat medium circuit 4 is provided in the second load device 20B1 for simultaneous heating and cooling operation. The rest of the configuration is the same as the heat pump apparatus 100A according to Embodiment 1, so further explanation will be omitted.

[0054] As described above, the heat pump apparatus 100 according to Embodiment 2 includes a heat source unit 10, which includes a first refrigerant circuit 1 that is capable of switching between the cooling operation and the heating operation and in which refrigerant circulates, and a first heat medium heat exchanger 16 that exchanges heat with the first refrigerant circuit 1. The heat pump apparatus 100 also includes the first load devices 20Aa, 20Ab, and 20Ac that have the first load-side heat exchangers 21Aa, 21Ab, and 21Ac. The heat pump apparatus 100 also includes the first heat medium circuit 3 in which the first heat medium heat exchanger 16 and the first load-side heat exchangers 21Aa, 21Ab, and 21Ac are connected by the outbound heat medium pipe 5a and the return heat medium pipe 5b and in which a heat medium circulates. The heat pump apparatus 100 also includes the second load device 20B1 that includes the second refrigerant circuit 2 that is capable of switching between the cooling operation and the heating operation and in which refrigerant circulates, the second heat medium heat exchanger 35 configured to exchange heat with the second refrigerant circuit 2, and the second heat medium circuit 4 in which the second heat medium heat exchanger 35 and the second load-side heat exchanger 21B are connected by the heat medium pipe and in which the heat medium circulates.

[0055] According to the heat pump apparatus 100A of Embodiment 2, when cooling and heating operation is performed simultaneously at a plurality of load devices, either the cooling operation or the heating operation can be performed with the first refrigerant circuit 1 in the heat source unit 10 and the second refrigerant circuit 2 in the relay unit 30 for each operation. As a result, the number of heat medium pipes connected to the heat source unit 10 can be reduced to two, namely, the outbound heat medium pipe 5a and the return heat medium pipe 5b. This lowers the pipe costs and reduces the burden of pipe construction. This, in turn, improves the ease of construction.REFERENCE SIGNS LIST1: first refrigerant circuit, 2: second refrigerant circuit, 3: first heat medium circuit, 4: second heat medium circuit, 5a: outbound heat medium pipe, 5b: return heat medium pipe, 10: heat source unit, 11: first compressor, 12: first flow switching device, 13: heat source-side heat exchanger, 14: heat source-side fan, 15: first expansion device, 16: first heat medium heat exchanger, 17: accumulator, 18: first pump, 19: opening-and-closing valve, 20A: first load device, 20Aa: first load device, 20Ab: first load device, 20Ac: first load device, 20B: second load device, 20B1: second load device, 21Aa: first load-side heat exchanger, 21Ab: first load-side heat exchanger, 21Ac: first load-side heat exchanger, 21B: second load-side heat exchanger, 22Aa: first load-side fan, 22Ab: first load-side fan, 22Ac: first load-side fan, 22B: second load-side fan, 30: relay unit, 31: second compressor, 32: second flow switching device, 33: third heat medium heat exchanger, 34: second expansion device, 35: second heat medium heat exchanger, 36: second pump, 40: controller, 100: heat pump apparatus

Examples

embodiment 1

[0015]FIG. 1 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100 according to Embodiment 1. As shown in FIG. 1, the heat pump apparatus 100 according to Embodiment 1 includes a heat source unit 10, a plurality of load devices (four in Embodiment 1), a relay unit 30, and a controller 40. Among the four load devices, three are first load devices 20Aa, 20Ab, and 20Ac for switching between cooling and heating operations, performing the same operation as each other. One is a second load device 20B for simultaneous cooling and heating operations, which performs the same or different operations as the first load devices 20Aa, 20Ab, and 20Ac. The heat pump apparatus 100 has a structure in which the heat source unit 10 and the three first load devices 20Aa, 20Ab, 20Ac are connected via two heat medium pipes (an outbound heat medium pipe 5a and return heat medium pipe 5b). Additionally, the three first load devices 20Aa, 20Ab, and 20Ac...

embodiment 2

[0052]The following describes Embodiment 2. Explanations are omitted for parts that overlap with Embodiment 1 and the same reference numerals are assigned to parts that are the same as or equivalent to those of Embodiment 1.

[0053]FIG. 6 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100A according to Embodiment 2. In the heat pump apparatus 100A according to Embodiment 2, as shown in FIG. 6, there is no relay unit 30, and in addition to the second refrigerant circuit 2, the second heat medium circuit 4 is provided in the second load device 20B1 for simultaneous heating and cooling operation. The rest of the configuration is the same as the heat pump apparatus 100A according to Embodiment 1, so further explanation will be omitted.

[0054]As described above, the heat pump apparatus 100 according to Embodiment 2 includes a heat source unit 10, which includes a first refrigerant circuit 1 that is capable of switching between the c...

TECHNICAL FIELD

[0001] The present disclosure relates to a heat pump apparatus.BACKGROUND ART

[0002] Traditionally, various heat pump apparatuses utilizing refrigerant and heat mediums have been disclosed (see, for example, Patent Literature 1). For instance, Patent Literature 1 discloses a cold-and-hot water multi-air conditioning device that includes two cold-and-hot water devices and a plurality of indoor units installed on each floor of a building. In this cold-and-hot water multi-air conditioning device, each outdoor unit is connected to a plurality of indoor units by cold-and-hot water pipes. An outdoor unit of one of the cold-and-hot water multi-air conditioning device is used for cooling operation, and an outdoor unit of the other of the cold-and-hot water multi-air conditioning device is used for heating operation, enabling simultaneous cooling and heating operation in each indoor unit.CITATION LISTPatent Literature

[0003] Patent Literature 1: JPH04-214134ASUMMARY OF INVENTIONTechnical Problem

[0004] However, in the cold-and-hot water multi-air conditioning device of Patent Literature 1, two cold-and-hot water pipes for circulating cold water connected to the outdoor unit of one of the cold-and-hot water multi-air conditioning devices, and two cold-and-hot water pipes for circulating hot water connected to the outdoor unit of the other of the cold-and-hot water multi-air conditioning devices, are required. Therefore, it is necessary to install two cold-and-hot water pipes to each outdoor unit placed outside, and due to the large number of cold-and-hot water pipes to be installed, the cost of piping becomes high and the burden of pipe construction increases, posing a problem of poor constructability.

[0005] The heat pump apparatus of the present disclosure is made to overcome the above-mentioned problems, and an object thereof is to provide a heat pump apparatus that reduces pipe costs and improves constructability by reducing the number of heat medium pipes connected to the heat source unit.Solution to Problem

[0006] A heat pump apparatus according to an embodiment of the present disclosure includes a heat source unit including a first refrigerant circuit configured to switch between cooling operation and heating operation, and in which refrigerant circulates, and a first heat medium heat exchanger configured to conduct heat exchange with the first refrigerant circuit, a relay unit including a second refrigerant circuit configured to switch between cooling operation and heating operation and in which refrigerant circulates, and a second heat medium heat exchanger configured to conduct heat exchange with the second refrigerant circuit, a first load device including a first load-side heat exchanger, a second load device including a second load-side heat exchanger, a first heat medium circuit in which the first heat medium heat exchanger and the first load-side heat exchanger are connected by an outbound heat medium pipe and a return heat medium pipe, and in which heat medium circulates, a second heat medium circuit in which the second heat medium heat exchanger and the second load-side heat exchanger are connected by a heat medium pipe, and in which a heat medium circulates.Advantageous Effects of Invention

[0007] According to an embodiment of the heat pump apparatus of the present disclosure, when cooling and heating operation is simultaneously performed at a plurality of load devices, either cooling or heating can be performed with the first refrigerant circuit in the heat source unit and the second refrigerant circuit in the relay unit for each operation. Therefore, the number of heat medium pipes connected to the heat source unit can be limited to two, namely, the outbound heat medium pipe and the return heat medium pipe. As a result, compared to traditional systems, the number of pipes connected to the heat source unit can be reduced, thereby lowering the pipe costs and reducing the burden of pipe construction. This, in turn, improves the ease of construction.BRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. 1 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus according to Embodiment 1.

[0009] FIG. 2 is a refrigerant circuit diagram that shows the flows of the refrigerant and the heat medium when the heat pump apparatus according to Embodiment 1 performs cooling only operation.

[0010] FIG. 3 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when heating only operation is performed in the heat pump apparatus according to Embodiment 1.

[0011] FIG. 4 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when cooling main operation is performed in the heat pump apparatus according to Embodiment 1.

[0012] FIG. 5 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when heating main operation is performed in the heat pump apparatus according to Embodiment 1.

[0013] FIG. 6 is a refrigerant circuit diagram showing an example of the circuit configuration of the heat pump apparatus according to Embodiment 2.DESCRIPTION OF EMBODIMENTS

[0014] Hereinafter, the embodiments of the present disclosure will be explained based on the drawings. However, the present disclosure is not limited to the embodiments described below. Furthermore, in the following drawings, the dimensional relationships of components may differ from those of the actual ones.Embodiment 1

[0015] FIG. 1 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100 according to Embodiment 1. As shown in FIG. 1, the heat pump apparatus 100 according to Embodiment 1 includes a heat source unit 10, a plurality of load devices (four in Embodiment 1), a relay unit 30, and a controller 40. Among the four load devices, three are first load devices 20Aa, 20Ab, and 20Ac for switching between cooling and heating operations, performing the same operation as each other. One is a second load device 20B for simultaneous cooling and heating operations, which performs the same or different operations as the first load devices 20Aa, 20Ab, and 20Ac. The heat pump apparatus 100 has a structure in which the heat source unit 10 and the three first load devices 20Aa, 20Ab, 20Ac are connected via two heat medium pipes (an outbound heat medium pipe 5a and return heat medium pipe 5b). Additionally, the three first load devices 20Aa, 20Ab, and 20Ac are connected in parallel to the heat source unit 10. Even though FIG. 1 shows three first load devices 20Aa, 20Ab, 20Ac, the number of the load devices is not limited to three, and could be any number as long as it's one or more. The heat source unit 10 is an outdoor unit, for example. The first load devices 20Aa, 20Ab, 20Ac and the second load device 20B are indoor units, as an example. The heat source unit 10 is installed, for instance, on the roof of a building. The relay unit 30, the first load devices 20Aa, 20Ab,20Ac, and the second load device 20B are installed inside the building, for instance. The heat source unit 10, the first load devices 20Aa, 20Ab, 20Ac, the second load device 20B, and the relay unit 30 are controlled by the controller 40.

[0016] In addition, the heat pump apparatus 100 comprises a first refrigerant circuit 1 and a second refrigerant circuit 2 in which refrigerant circulates, as well as a first heat medium circuit 3 and a second heat medium circuit 4 in which a heat medium circulates. The first refrigerant circuit 1, for example, has a structure in which a first compressor 11, a first flow switching device 12, a heat source-side heat exchanger 13, a first expansion device 15, a first heat medium heat exchanger 16, and an accumulator 17 are cyclically connected in this order via a refrigerant pipe. The second refrigerant circuit 2, for example, has a structure in which a second compressor 31, a second flow switching device 32, a third heat medium heat exchanger 33, a second expansion device 34, and a second heat medium heat exchanger 35 are cyclically connected in this order via a refrigerant pipe. The first heat medium circuit 3, for example, has a structure in which a first pump 18, the first heat medium heat exchanger 16, the third heat medium heat exchanger 33, and the first load devices 20Aa, 20Ab, 20Ac are cyclically connected in this order via an outbound heat medium pipe 5a and a return heat medium pipe 5b. The second heat medium circuit 4, for example, has a structure in which a second pump 36, the second heat medium heat exchanger 35, and the second load device 20B are cyclically connected in this order via a heat medium pipe. In Embodiment 1, the first refrigerant circuit 1 is installed in the heat source unit 10, while the second refrigerant circuit 2 is installed in the relay unit 30.

[0017] The refrigerant filled into the first refrigerant circuit 1 and the second refrigerant circuit 2 can be, for example, a single-component refrigerant such as R1234yf, R1234ze, R32, and R290, or a mixed refrigerant of two or more of these, or a mixed refrigerant of any of these with another refrigerant, a mixed refrigerant including R1132(E), or a mixed refrigerant including R1123. Additionally, mixed refrigerants such as R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, and R459A can be utilized. The refrigerant filled into the first refrigerant circuit 1 and the refrigerant filled into the second refrigerant circuit 2 may be the same or different.

[0018] Examples of the heat medium filled in the first heat medium circuit 3 and the second heat medium circuit 4 include, for instance, water and brine. Additionally, the heat medium filled in the first heat medium circuit 3 and the heat medium filled in the second heat medium circuit 4 may be the same or different.Heat Source Unit 10

[0019] The heat source unit 10 comprises the first compressor 11, the first flow switching device 12, the heat source-side heat exchanger 13, the heat source-side fan 14, the first expansion device 15, the first heat medium heat exchanger 16, the accumulator 17, the first pump 18, and an opening-and-closing valve 19. The first compressor 11 suctions and compresses the refrigerant into a high-temperature, high-pressure state. The first compressor 11 comprises a capacity-controllable inverter compressor, for example. The first compressor 11 utilized may be of a low-pressure shell-structure type. The compressor with a low-pressure shell structure has a compression chamber within a sealed container, which creates a low refrigerant pressure atmosphere. It suctions and compresses the low-pressure refrigerant within the sealed container. The first flow switching device 12 is a four-way valve for example, and can switch between cooling and heating operation by redirecting the flow of the refrigerant. The first flow switching device could also be formed using a combination of two-way and three-way valves as an alternative to the four-way valve. The heat source-side heat exchanger 13 can serve as an evaporator or condenser, conducting heat exchange between the air and the refrigerant to evaporate and gasify or condense and liquefy the refrigerant. The heat source-side heat exchanger 13 serves as an evaporator during the heating operation and as a condenser during the cooling operation. The heat source-side fan 14 is installed near the heat source-side heat exchanger 13, and supplies air to the heat source-side heat exchanger 13. The first expansion device 15 depressurizes and expands the refrigerant. The first expansion valve may be an electronic expansion valve, for example, capable of adjusting the opening degree. By adjusting the opening degree, it regulates the pressure of the refrigerant flowing into the heat source-side heat exchanger 13 during the heating operation, and the pressure of the refrigerant flowing into the first heat medium heat exchanger 16 during the cooling operation. The first heat medium heat exchanger 16 has a heat transfer portion for passing refrigerant and another heat transfer portion for passing a heat medium, conducting heat exchange between the refrigerant and the heat medium. During heating operation, the first heat medium heat exchanger 16 serves as a condenser, allowing the refrigerant to heat the heat medium by radiating heat from the refrigerant. On the other hand, during the cooling operation, the first heat medium heat exchanger to serve as an evaporator, allowing the refrigerant to cool the heat medium by absorbing heat. The accumulator 17, located on the suction side of the first compressor 11, stores excess refrigerant generating due to the difference in necessary refrigerant quantity between heating and cooling operations, or transient operation changes. The first pump 18 is a heat medium sending device that pumps the heat medium to circulate in the second heat medium circuit 4. By varying the rotation speed of its built-in motor (not shown), the first pump can adjust the discharge flow volume of heat medium pumped out. Constructed as a two-way valve, for instance, the opening-and-closing valve 19 can control the passage of heat medium by its opening and closing.First Load Devices 20Aa, 20Ab, 20Ac

[0020] The first load devices 20Aa, 20Ab, and 20Ac each serve to supply heat from the heat source unit 10 for the cooling load or heating load, and to perform air conditioning or heating for the air-conditioning target space. The first load device 20Aa includes a first load-side heat exchanger 21Aa and a first load-side fan 22Aa. The first load device 20Ab includes a first load-side heat exchanger 21Ab and a first load-side fan 22Ab. The first load device 20Ac includes a first load-side heat exchanger 21Ac and a first load-side fan 22Ac.

[0021] In the following explanation, when there is no particular need to distinguish between the first load device 20Aa, the first load device 20Ab, and the first load device 20Ac, they will simply be referred to as “the first load device 20A” as appropriate. Additionally, the first load-side heat exchanger 21Aa, the first load-side heat exchanger 21Ab, and the first load-side heat exchanger 21Ac have the same configuration, and the first load-side fan 22Aa, the first load-side fan 22Ab, the and the first load-side fan 22Ac also have the same configuration. Therefore, the following explanation will use the first load-side heat exchanger 21Aa and the first load-side fan 22Aa as examples.

[0022] The first load-side heat exchanger 21Aa conducts heat exchange between indoor air and the heat medium. Specifically, during a cooling operation, the first load-side heat exchanger 21Aa cools the indoor air by allowing the heat medium to absorb heat. Additionally, during a heating operation, the first load-side heat exchanger 21Aa heats the indoor air by allowing the heat medium to reject heat. Note that the first load-side heat exchanger 21Aa is installed to have indoor air blown by the first load-side fan 22Aa installed nearby.Second Load Device 20B

[0023] The second load device 20B supplies heat from the relay unit 30 to the cooling load or the heating load, performing either cooling operation or heating operation for the air-conditioning target space. The second load device 20B includes a second load-side heat exchanger 21B and a second load-side fan 22B.

[0024] The second load-side heat exchanger 21B conducts heat exchange between the indoor air and the heat medium. Specifically, during a cooling operation, the second load-side heat exchanger 21B cools the indoor air by allowing the heat medium to absorb heat. Additionally, during a heating operation, the second load-side heat exchanger 21B heats the indoor air by allowing the heat medium to reject heat. Note that the second load-side heat exchanger 21B is installed to have indoor air blown by the second load-side fan 22B installed nearby.Relay Unit 30

[0025] The relay unit 30 includes the second compressor 31, the second flow switching device 32, the third heat medium heat exchanger 33, the second expansion device 34, the second heat medium heat exchanger 35, and the second pump 36. The second compressor 31 suctions and compresses the refrigerant, putting it under a high-temperature, high-pressure state. The second compressor 31 may be a capacity-controllable inverter compressor, for example. The second compressor 31, for example, can be of a low-pressure shell structure. The compressor with a low-pressure shell structure has a compression chamber within a sealed container, which creates a low refrigerant pressure atmosphere. It suctions and compresses the low-pressure refrigerant within the sealed container. The second flow switching device 32, which is, for example, a four-way valve, configured to switch between cooling operation and heating operation by changing the direction of the refrigerant flow. Instead of a four-way valve, a combination of a two-way and a three-way valve can also be used for the second flow switching device 32. The third heat medium heat exchanger 33 has a heat transfer portion for passing refrigerant and another heat transfer portion for passing a heat medium, conducting heat exchange between the refrigerant and the heat medium. The third heat medium heat exchanger 33 serves as a condenser during cooling operation, causing the refrigerant to reject heat to heat the heat medium. On the other hand, the third heat medium heat exchanger 33 serves as an evaporator during heating operation, causing the refrigerant to absorb heat to cool the heat medium. The second expansion device 34 depressurizes and expands the refrigerant. The second expansion device 34 is, for example, an electronic expansion valve with adjustable opening degree, and by adjusting the opening degree thereof, it controls the pressure of refrigerant flowing into the third heat medium heat exchanger 33 during heating operation and the pressure of refrigerant flowing into the second heat medium heat exchanger 35 during cooling operation. The second heat medium heat exchanger 35 has a heat transfer portion for passing refrigerant and another heat transfer portion for passing a heat medium, conducting heat exchange between the refrigerant and the heat medium. The second heat medium heat exchanger 35 serves as a condenser during heating operation by causing the refrigerant to reject heat to the heat medium and heat the heat medium, while it serves as an evaporator during cooling operation by causing the refrigerant to absorb heat from the heat medium to cool the heat medium. The second pump 36 is a heat medium sending device that pumps the heat medium to circulate it in the first heat medium circuit 3. The second pump 36 can vary the discharge flow rate, which is the volume of the heat medium being pumped out, by changing the rotation speed of its built-in motor (not shown in the figure) within a certain range.Controller 40

[0026] The controller 40 controls the entire heat pump apparatus 100. For example, depending on the operating actions of the heat pump apparatus 100, the controller 40 controls the first refrigerant circuit 1, the second refrigerant circuit 2, the first heat medium circuit 3, and the second heat medium circuit 4. The various functions of the controller 40 are achieved by executing software on computing devices like microcomputers, or it may be comprised of hardware such as circuit devices that implement various functions.

[0027] Next, the operational behaviors during various operations that the heat pump apparatus 100 performs are described. The operations of the heat pump apparatus100 include four types: cooling only operation, heating only operation, cooling main operation, and heating main operation.

[0028] “Cooling only operation” refers to an operational mode in which only cooling operation is possible in the first load device 20A and the second load device 20B, signifying the state in which the first load device 20A and the second load device 20B are performing cooling operation. “Heating only operation” refers to an operational mode in which only heating operation is possible at the first load device 20A and the second load device 20B, signifying the state in which the first load device 20A and the second load device 20B are performing heating operation. “Cooling main operation” refers to an operational mode in which the cooling load surpasses the heating load under simultaneous cooling and heating operation in which the first load device 20A performs cooling operation and the second load device 20B performs heating operation. “Heating main operation” refers to an operational mode in which the heating load surpasses the cooling load under simultaneous cooling and heating operation in which the first load device 20A performs heating operation and the second load device 20B performs cooling operation.Cooling Only Operation

[0029] Firstly, with reference to FIG. 2, the cooling only operation of the heat pump apparatus 100 is explained. FIG. 2 is a refrigerant circuit diagram that shows the flows of the refrigerant and the heat medium when the heat pump apparatus according to Embodiment 1 performs cooling only operation. Moreover, the solid arrows shown in FIG. 2 indicate the flow of the refrigerant, while the hollow arrows indicate the flow of the heat medium.

[0030] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant discharged from the first compressor 11 passes through the first flow switching device 12 to the heat source-side heat exchanger 13, where it conducts heat exchange with outdoor air to condense and liquefy. The condensed and liquefied refrigerant is depressurized by the first expansion device 15, becoming a low-pressure two-phase gas-liquid refrigerant, and flows into the first heat medium heat exchanger 16, where it exchanges heat with the heat medium flowing in the first heat medium circuit 3 to evaporate and gasify. The evaporated and gasified refrigerant passes through the first flow switching device 12, and is suctioned again into the first compressor 11 via the accumulator 17.

[0031] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 and to the third heat medium heat exchanger 33, where exchanges heat exchange with the heat medium flowing in the first heat medium circuit 3 to condense and liquefy. The condensed, liquefied refrigerant is depressurized in the second expansion device 34, becoming a low-pressure two-phase gas-liquid refrigerant, and flows into the second heat medium heat exchanger 35, where it exchanges heat with the heat medium flowing in the second heat medium circuit 4 to evaporate and gasify. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is suctioned back into the second compressor 31.

[0032] In the first heat medium circuit 3, the heat medium, pumped out by the first pump 18, is cooled by the refrigerant flowing through the first heat medium heat exchanger 16 and becomes cold water. The heat medium then flows into the first load-side heat exchangers 21Aa, 21Ab, and 21Ac, where it undergoes a heat exchange with the indoor air in the room, and is heated, while the indoor air is cooled in the process. The heated heat medium then flows into the third heat medium heat exchanger 33, where it is further heated by exchanging heat with the refrigerant flowing through the second refrigerant circuit 2. The heated heat medium is then suctioned back into the first pump 18 again.

[0033] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 is cooled by the refrigerant that flows through the second heat medium heat exchanger 35, becoming cold water. The heat medium then flows into the second load-side heat exchanger 21B, where it exchanges heat with indoor air in the indoor space, to be heated while cooling the indoor air. The heated heat medium is then suctioned back in by the second pump 36.Heating Only Operation

[0034] The following describes the heating only operation of the heat pump apparatus 100 with reference to FIG. 3. FIG. 3 is a refrigerant circuit diagram showing the flows of refrigerant and the heat medium when the heat pump apparatus 100, according to embodiment 1, performs a heating only operation. Note that the solid arrows shown in FIG. 3 indicate the flow of refrigerant, and the hollow arrow indicates the flow of the heat medium.

[0035] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant discharged from the first compressor 11 passes through the first flow switching device 12 and flows into the first heat medium heat exchanger 16. The refrigerant flowing into the first heat medium heat exchanger 16 exchanges heat with the heat medium flowing through the first heat medium circuit 3 to condense and liquefy, and is depressurized by the first expansion device 15, becoming a low-pressure, two-phase gas-liquid refrigerant that then flows to the heat source-side heat exchanger 13. The two-phase gas-liquid refrigerant flowing into the heat source-side heat exchanger 13 exchanges heat with the outside air to evaporate and gasify, then it passes through the first flow switching device 12 and is suctioned into the first compressor 11 via the accumulator 17.

[0036] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 and flows into the second heat medium heat exchanger 35 where it exchanges heat with the heat medium flowing in the second heat medium circuit 4 to condense and liquefy. The condensed and liquefied refrigerant is depressurized by the second expansion device 34, becoming a low-pressure, two-phase gas-liquid refrigerant, and then flows into the third heat medium heat exchanger 33 where it exchanges heat with the heat medium flowing through the first heat medium circuit 3 to evaporate and gasify. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is again suctioned into the second compressor 31.

[0037] In the first heat medium circuit 3, the heat medium pumped out by the first pump 18 becomes hot water after being heated by the refrigerant flowing through the first heat medium heat exchanger 16. It then flows into the first load-side heat exchangers 21Aa, 21Ab, 21Ac, where it exchanges heat with indoor air, to be cooled and heating the indoor air. The cooled heat medium flows into the third heat medium heat exchanger 33 and exchanges heat with the refrigerant flowing in the second refrigerant circuit 2, to be cooled. The cooled heat medium is then suctioned back into the first pump 18.

[0038] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 becomes hot water after being heated by the refrigerant flowing through the second heat medium heat exchanger 35. This hot water flows into the second load-side heat exchanger 21B, where it exchanges heat with the indoor air in the room and is cooled, while heating the indoor air. The cooled heat medium is suctioned again by the second pump 36,Cooling Main Operation

[0039] The following describes, with reference to FIG. 4, the case where cooling operation is performed by the first load device 20A, heating operation is performed by the second load device 20B, and a cooling main operation with a large cooling load is performed. FIG. 4 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when the cooling main operation is performed in the heat pump apparatus 100 according to Embodiment 1. Note that the solid arrows shown in FIG. 4 indicates the flow of refrigerant, and the hollow arrows represent the flow of the heat medium.

[0040] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant that is discharged from the first compressor 11 passes through the first flow switching device 12 and flows into the heat source-side heat exchanger 13, where it exchanges heat with the outdoor air to condense and liquefy. The condensed and liquefied refrigerant is depressurized by the first expansion device 15 and becomes a low-pressure two-phase gas-liquid refrigerant, which then flows into the first heat medium heat exchanger 16 and exchanges heat with the heat medium flowing through the first heat medium circuit 3 to be evaporated and gasified. The evaporated and gasified refrigerant passes through the first flow switching device 12, and is suctioned again into the first compressor 11 via the accumulator 17.

[0041] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 to the second heat medium heat exchanger 35, where it exchanges heat with the heat medium flowing in the second heat medium circuit 4, to be condensed and liquefied. The condensed and liquefied refrigerant is then depressurized by the second expansion device 34, becoming a low-pressure, two-phase gas-liquid refrigerant, which flows into the third heat medium heat exchanger 33. There, it exchanges heat with the heat medium flowing through the first heat medium circuit 3, to be evaporated and gasified. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is suctioned back into the second compressor 31.

[0042] In the first heat medium circuit 3, the heat medium pumped out by the first pump 18 is cooled by the refrigerant flowing through the first heat medium heat exchanger 16, turning it into cold water. This cold water then flows into the first load-side heat exchangers 21Aa, 21Ab, and 21Ac, where it exchanges heat with the indoor air in the room, being heated while cooling the air. The heated heat medium then flows into the third heat medium heat exchanger 33, where it exchanges heat with the refrigerant flowing through the second refrigerant circuit 2, to be cooled. The cooled heat medium is then suctioned back into the first pump 18.

[0043] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 is heated by the refrigerant flowing through the second heat medium heat exchanger 35, becoming hot water. This hot water then flows into the second load-side heat exchanger 21B where it exchanges heat with the indoor air within the indoor space, to be cooled while heating the indoor air. The cooled heat medium is then suctioned back into the second pump 36.Heating Main Operation

[0044] The following describes, with reference to FIG. 5, the case where heating operation is performed by the first load device 20A, and cooling operation is performed by the second load device 20B, and the explanation follows of the case where the heating operation, which has a high load, known as heating main operation is performed. FIG. 5 is a refrigerant circuit diagram showing the flows of the refrigerant and the heat medium when the heating main operation is performed in the heat pump apparatus 100 according to Embodiment 1. The solid arrows shown in FIG. 5 indicate the flow of the refrigerant, while the hollow arrows indicate the flow of the heat medium.

[0045] In the first refrigerant circuit 1, the high-temperature, high-pressure gas refrigerant discharged from the first compressor 11 passes through the first flow switching device 12 and flows into the first heat medium heat exchanger 16. The refrigerant flowing into the first heat medium heat exchanger 16 exchanges heat with the heat medium flowing through the first heat medium circuit 3, to be condensed and liquefied. Then the condensed and liquefied refrigerant is depressurized by the first expansion device 15 to become a low-pressure, two-phase gas-liquid refrigerant, which flows into the heat source-side heat exchanger 13. The two-phase gas-liquid refrigerant flowing into the heat source-side heat exchanger 13 exchanges heat with outdoor air to be evaporated and gasified, then passes through the first flow switching device 12 and is suctioned into the first compressor 11 via the accumulator 17.

[0046] In the second refrigerant circuit 2, the high-temperature, high-pressure gas refrigerant discharged from the second compressor 31 passes through the second flow switching device 32 and flows into the third heat medium heat exchanger 33. Here, the high-temperature, high-pressure gas refrigerant exchanges heat with the heat medium flowing through the first heat medium circuit 3, to be condensed and liquefied. The condensed and liquefied refrigerant is depressurized by the second expansion device 34, becoming a low-pressure two-phase gas-liquid refrigerant. The low-pressure two-phase gas-liquid refrigerant then flows into the second heat medium heat exchanger 35 and exchanges heat with the heat medium flowing through the second heat medium circuit 4, to be evaporated and gasified. The evaporated and gasified refrigerant passes through the second flow switching device 32 and is once again suctioned into the second compressor 31.

[0047] In the first heat medium circuit 3, the heat medium pumped out by the first pump 18 is heated by the refrigerant flowing through the first heat medium heat exchanger 16, becoming hot water. This hot water then passes through the first load-side heat exchangers 21Aa, 21Ab, 21Ac, where it exchanges heat with indoor air in the room, being cooled in the process while heating the indoor air. The cooled heat medium then flows into the third heat medium heat exchanger 33, where it is heated by exchanging heat with the refrigerant flowing through the second refrigerant circuit 2. The heated heat medium is then suctioned back into the first pump 18.

[0048] In the second heat medium circuit 4, the heat medium pumped out by the second pump 36 is cooled by the refrigerant flowing through the second heat medium heat exchanger 35, becoming cold water. Then, it flows into the second load-side heat exchanger 21B where it exchanges heat with the indoor air in the room to be heated while the indoor air is cooled. The heated heat medium is again suctioned into the second pump 36.

[0049] From the above, with the heat pump apparatus 100 according to Embodiment 1, when both the cooling operation and the heating operating is simultaneously performed with a plurality of load devices, a first refrigerant circuit 1, provided at the heat source unit 10, and a second refrigerant circuit 2, provided at the relay unit 30, can carry out either cooling operation or heating operation individually. Therefore, the number of heat medium pipes connected to the heat source unit 10 can be reduced to two, namely, the outbound heat medium pipe 5a and return heat medium pipe 5b. Consequently, this reduction in the number of pipes connected to the heat source unit 10 over the conventional systems can lower pipe costs, reduce the burden of pipe construction, and improve the ease of construction.

[0050] As described above, the heat pump apparatus 100 according to Embodiment 1 includes the heat source unit 10, which has the first refrigerant circuit 1 in which refrigerant circulates, and which is capable of switching between the cooling operation and the heating operation, and the first heat medium heat exchanger 16 that exchanges heat with the first refrigerant circuit 1. The heat pump apparatus 100 also includes the relay unit 30 that includes the second refrigerant circuit 2 which is capable of switching between the cooling operation and the heating operation and in which refrigerant circulates, and the second heat medium heat exchanger 35 that exchanges heat with the second refrigerant circuit 2. The heat pump apparatus 100 also includes a first load devices 20Aa, 20Ab, and 20Ac that have first load-side heat exchangers 21Aa, 21Ab, and 21Ac, and a second load device 20B that includes a second load-side heat exchanger 21B. The heat pump apparatus 100 also includes a first heat medium circuit 3 in which a heat medium circulates and in which the first heat medium heat exchanger 16 and the first load-side heat exchangers 21Aa, 21Ab, and 21Ac are connected by the outbound heat medium pipe 5a and a return heat medium pipe 5b. The heat pump apparatus 100 also includes a second heat medium circuit 4, and the second heat medium heat exchanger 35 and the second load-side heat exchanger 21B are connected by a heat medium pipe in which a heat medium circulates.

[0051] According to Embodiment 1 of the heat pump apparatus 100, when the cooling operation and the heating operation are simultaneously performed at a plurality of load devices, either the cooling operation or the heating operation can be performed with the first refrigerant circuit 1 in the heat source unit 10 and the second refrigerant circuit 2 in the relay unit 30 for each operation. Therefore, the number of heat medium pipes connected to the heat source unit 10 can be limited to two, namely, the outbound heat medium pipe 5a and the return heat medium pipe 5b. As a result, compared to traditional systems, the number of pipes connected to the heat source unit 10 can be reduced, thereby lowering the pipe costs and reducing the burden of pipe construction. This, in turn, improves the ease of construction.Embodiment 2

[0052] The following describes Embodiment 2. Explanations are omitted for parts that overlap with Embodiment 1 and the same reference numerals are assigned to parts that are the same as or equivalent to those of Embodiment 1.

[0053] FIG. 6 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100A according to Embodiment 2. In the heat pump apparatus 100A according to Embodiment 2, as shown in FIG. 6, there is no relay unit 30, and in addition to the second refrigerant circuit 2, the second heat medium circuit 4 is provided in the second load device 20B1 for simultaneous heating and cooling operation. The rest of the configuration is the same as the heat pump apparatus 100A according to Embodiment 1, so further explanation will be omitted.

[0054] As described above, the heat pump apparatus 100 according to Embodiment 2 includes a heat source unit 10, which includes a first refrigerant circuit 1 that is capable of switching between the cooling operation and the heating operation and in which refrigerant circulates, and a first heat medium heat exchanger 16 that exchanges heat with the first refrigerant circuit 1. The heat pump apparatus 100 also includes the first load devices 20Aa, 20Ab, and 20Ac that have the first load-side heat exchangers 21Aa, 21Ab, and 21Ac. The heat pump apparatus 100 also includes the first heat medium circuit 3 in which the first heat medium heat exchanger 16 and the first load-side heat exchangers 21Aa, 21Ab, and 21Ac are connected by the outbound heat medium pipe 5a and the return heat medium pipe 5b and in which a heat medium circulates. The heat pump apparatus 100 also includes the second load device 20B1 that includes the second refrigerant circuit 2 that is capable of switching between the cooling operation and the heating operation and in which refrigerant circulates, the second heat medium heat exchanger 35 configured to exchange heat with the second refrigerant circuit 2, and the second heat medium circuit 4 in which the second heat medium heat exchanger 35 and the second load-side heat exchanger 21B are connected by the heat medium pipe and in which the heat medium circulates.

[0055] According to the heat pump apparatus 100A of Embodiment 2, when cooling and heating operation is performed simultaneously at a plurality of load devices, either the cooling operation or the heating operation can be performed with the first refrigerant circuit 1 in the heat source unit 10 and the second refrigerant circuit 2 in the relay unit 30 for each operation. As a result, the number of heat medium pipes connected to the heat source unit 10 can be reduced to two, namely, the outbound heat medium pipe 5a and the return heat medium pipe 5b. This lowers the pipe costs and reduces the burden of pipe construction. This, in turn, improves the ease of construction.REFERENCE SIGNS LIST1: first refrigerant circuit, 2: second refrigerant circuit, 3: first heat medium circuit, 4: second heat medium circuit, 5a: outbound heat medium pipe, 5b: return heat medium pipe, 10: heat source unit, 11: first compressor, 12: first flow switching device, 13: heat source-side heat exchanger, 14: heat source-side fan, 15: first expansion device, 16: first heat medium heat exchanger, 17: accumulator, 18: first pump, 19: opening-and-closing valve, 20A: first load device, 20Aa: first load device, 20Ab: first load device, 20Ac: first load device, 20B: second load device, 20B1: second load device, 21Aa: first load-side heat exchanger, 21Ab: first load-side heat exchanger, 21Ac: first load-side heat exchanger, 21B: second load-side heat exchanger, 22Aa: first load-side fan, 22Ab: first load-side fan, 22Ac: first load-side fan, 22B: second load-side fan, 30: relay unit, 31: second compressor, 32: second flow switching device, 33: third heat medium heat exchanger, 34: second expansion device, 35: second heat medium heat exchanger, 36: second pump, 40: controller, 100: heat pump apparatus

Examples

embodiment 1

[0015]FIG. 1 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100 according to Embodiment 1. As shown in FIG. 1, the heat pump apparatus 100 according to Embodiment 1 includes a heat source unit 10, a plurality of load devices (four in Embodiment 1), a relay unit 30, and a controller 40. Among the four load devices, three are first load devices 20Aa, 20Ab, and 20Ac for switching between cooling and heating operations, performing the same operation as each other. One is a second load device 20B for simultaneous cooling and heating operations, which performs the same or different operations as the first load devices 20Aa, 20Ab, and 20Ac. The heat pump apparatus 100 has a structure in which the heat source unit 10 and the three first load devices 20Aa, 20Ab, 20Ac are connected via two heat medium pipes (an outbound heat medium pipe 5a and return heat medium pipe 5b). Additionally, the three first load devices 20Aa, 20Ab, and 20Ac...

embodiment 2

[0052]The following describes Embodiment 2. Explanations are omitted for parts that overlap with Embodiment 1 and the same reference numerals are assigned to parts that are the same as or equivalent to those of Embodiment 1.

[0053]FIG. 6 is a refrigerant circuit diagram showing an example of the circuit configuration of a heat pump apparatus 100A according to Embodiment 2. In the heat pump apparatus 100A according to Embodiment 2, as shown in FIG. 6, there is no relay unit 30, and in addition to the second refrigerant circuit 2, the second heat medium circuit 4 is provided in the second load device 20B1 for simultaneous heating and cooling operation. The rest of the configuration is the same as the heat pump apparatus 100A according to Embodiment 1, so further explanation will be omitted.

[0054]As described above, the heat pump apparatus 100 according to Embodiment 2 includes a heat source unit 10, which includes a first refrigerant circuit 1 that is capable of switching between the c...

Claims

1. A heat pump apparatus comprising:a heat source unit including a first refrigerant circuit configured to switch between cooling operation and heating operation, and in which refrigerant circulates, and a first heat medium heat exchanger configured to conduct heat exchange with the first refrigerant circuit,a relay unit configured to switch between cooling operation and heating operation, and including a second refrigerant circuit that can switch between cooling operation and heating operation and in which refrigerant circulates, and including a second heat medium heat exchanger and a third heat medium heat exchanger, the second and third heat exchangers being configured to conduct heat exchange with the second refrigerant circuit,a first load device including a first load-side heat exchanger,a second load device includinga second load-side heat exchanger,a first heat medium circuit in which the first heat medium heat exchanger, the third heat medium heat exchanger and the first load-side heat exchanger are connected by an outbound heat medium pipe and a return heat medium pipe, and in which heat medium circulates, anda second heat medium circuit in which a second heat medium heat exchanger and the second load-side heat exchanger are connected by a heat medium pipe, and in which a heat medium circulates.

2. A heat pump apparatus comprising:a heat source unit including a first refrigerant circuit configured to switch between cooling operation and heating operation, and in which refrigerant circulates, and a first heat medium heat exchanger configured to conduct heat exchange with the first refrigerant circuit,a first load device including a first load-side heat exchanger,a first heat medium circuit in which the first heat medium heat exchanger and the first load-side heat exchanger are connected by an outbound heat medium pipe and a return heat medium pipe, and in which heat medium circulates, anda second load device includinga second refrigerant circuit configured to switch between cooling operation and heating operation, and in which refrigerant circulates,a second heat medium heat exchanger and a third heat medium heat exchanger, the second and third heat medium heat exchangers being configured to conduct heat exchange with the second refrigerant circuit, anda second heat medium circuit in which the second heat medium heat exchanger and the second load-side heat exchanger are connected by the heat medium pipe, and in which heat medium circulates,wherein in the first heat medium circuit, the first heat medium heat exchanger, the third heat medium heat exchanger and the first load-side heat exchanger are connected by an outbound heat medium pipe and a return heat medium pipe.

3. A heat pump apparatus of claim 1, being configured such thatthe first heat medium heat exchanger and the second heat medium heat exchanger are each configured to,during cooling operation, serve as an evaporator, andduring heating operation, serve as a condenser, andand are configured such thatthe first heat medium heat exchanger serve as an evaporator and the second heat medium heat exchanger serves as a condenser, or the first heat medium heat exchanger serves as a condenser and the second heat medium heat exchanger serves as an evaporator.

4. The heat pump apparatus of claim 2,whereinthe first heat medium heat exchanger and the second heat medium heat exchanger are each configured to,during cooling operation, serve as an evaporator, andduring heating operation, serve as a condenser, andand are configured such thatthe first heat medium heat exchanger serve as an evaporator and the second heat medium heat exchanger serves as a condenser, or the first heat medium heat exchanger serves as a condenser and the second heat medium heat exchanger serves as an evaporator.

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