JP2022159197A - Refrigeration cycle device - Google Patents

Abstract

To provide a refrigeration cycle device comprising a first refrigerant circuit and a second refrigerant circuit, and enabling efficient operation.SOLUTION: A refrigeration cycle device comprises a first refrigerant circuit (10) using a first refrigerant of 1.2 MPa or less at 30°C, and a second refrigerant circuit (20) using a second refrigerant of 1.5 MPa or more at 30°C. The refrigeration cycle device can switch between a binary cycle operation in which the first refrigerant circuit (10) and the second refrigerant circuit (20) are simultaneously operated to perform heat exchange between the first refrigerant and the second refrigerant, and a unit cycle operation in which the first refrigerant circuit (10) is operated without operating the second refrigerant circuit (20), to perform cooling operation or heating operation.SELECTED DRAWING: Figure 3

Description

It relates to a refrigeration cycle device.

BACKGROUND ART Conventionally, there is a binary refrigeration cycle device in which two refrigerant circuits are operated and heat is exchanged between refrigerants flowing through the respective refrigerant circuits.

For example, the refrigeration cycle device described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2014-9829) includes a heat source side refrigerant circuit and a user side refrigerant circuit that are thermally connected via a cascade heat exchanger. It is proposed to efficiently operate the dual refrigeration cycle when both the heat source side compressor of the circuit and the user side compressor of the user side refrigerant circuit are driven.

In this refrigerating cycle device, it is desired that the refrigerating cycle device including the first refrigerant circuit and the second refrigerant circuit is operated more efficiently by different methods.

A refrigeration cycle device according to a first aspect includes a first refrigerant circuit using a first refrigerant and a second refrigerant circuit using a second refrigerant. The first refrigerant is 1.2 MPa or less at 30°C. The second refrigerant is 1.5 MPa or more at 30°C. The refrigeration cycle apparatus can switch between binary cycle operation and single cycle operation. In the two-way cycle operation, the first refrigerant circuit and the second refrigerant circuit are operated simultaneously to exchange heat between the first refrigerant and the second refrigerant. Unit cycle operation performs cooling operation or heating operation by operating the first refrigerant circuit without operating the second refrigerant circuit.

Note that the refrigeration cycle apparatus may perform either cooling operation or heating operation as the unit cycle operation, or may selectively perform both the cooling operation and the heating operation as the unit cycle operation. good.

Moreover, the first refrigerant circuit and the second refrigerant circuit may be refrigerant circuits independent of each other, and the first refrigerant and the second refrigerant may not be mixed.

When a dual refrigeration cycle is performed in the refrigeration cycle apparatus, the second refrigerant circuit side may be used as the heat source side, and the first refrigerant circuit side may be used as the user side. Specifically, the first refrigerant circuit may handle a heat load.

On the user side, the heat load of air may be processed, or the heat load of fluid such as water or brine may be processed.

In this refrigeration cycle device, a refrigeration cycle in a first refrigerant circuit using a first refrigerant that is a low-pressure refrigerant of 1.2 MPa or less at 30° C. and a second refrigerant that is a high-pressure refrigerant of 1.5 MPa or more at 30° C. By performing a dual refrigerating cycle including the refrigerating cycle in the second refrigerant circuit used, it is easy to secure the capacity while improving the operating efficiency. Further, in this refrigeration cycle apparatus, for example, when the heating load is small during heating operation, the first refrigerant circuit is operated without operating the second refrigerant circuit instead of performing the binary refrigeration cycle. By performing the above, it is possible to avoid a loss caused by heat exchange between the first refrigerant and the second refrigerant at low load, and to suppress a decrease in operating efficiency.

A refrigerating cycle device according to a second aspect is the refrigerating cycle device according to the first aspect, wherein the second refrigerant flowing through the second refrigerant circuit heats the first refrigerant flowing through the first refrigerant circuit during binary cycle operation. Start heating operation.

Note that it is preferable to perform the heating operation in the two-way cycle operation when the heating load is greater than a predetermined heating load.

In this refrigerating cycle apparatus, operating efficiency can be improved by performing a dual refrigerating cycle during heating operation.

A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first aspect or the second aspect, and performs unit cycle operation when a predetermined low load condition is satisfied.

Note that when the heating load satisfies a predetermined low load condition, it is preferable to perform the heating operation by the unit cycle operation.

With this refrigeration cycle apparatus, it is possible to suppress a decrease in the operating efficiency of the heating operation during a low load.

A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to any one of the first to third aspects, and includes a cascade heat exchanger. The cascade heat exchanger has a first cascade flowpath for flowing a first refrigerant and a second cascade flowpath for flowing a second refrigerant, independent of the first cascade flowpath. The cascade heat exchanger allows heat exchange between the first refrigerant and the second refrigerant during binary cycle operation.

In this refrigerating cycle device, it is possible to process the load using the heat obtained from the second refrigerating circuit side to the first refrigerating circuit side during dual refrigerating cycle operation.

A refrigeration cycle device according to a fifth aspect is the refrigeration cycle device according to the fourth aspect, wherein the first refrigerant circuit includes a first compressor, a first heat exchanger, a first expansion valve, and a first cascade flow path. and have

In this refrigeration cycle device, it is possible to perform a refrigeration cycle using the first refrigerant in the first refrigerant circuit by operating the first compressor.

A refrigeration cycle device according to a sixth aspect is the refrigeration cycle device according to the fifth aspect, wherein the second refrigerant circuit includes a second compressor, a second cascade flow path, a second expansion valve, and a second heat exchanger. and have

In this refrigerating cycle apparatus, a dual refrigerating cycle can be performed by operating the first compressor and the second compressor.

A refrigeration cycle device according to a seventh aspect is the refrigeration cycle device according to the sixth aspect, wherein the first cascade flow path functions as an evaporator for the first refrigerant and the first heat exchanger functions as the first refrigerant during binary cycle operation. It functions as a radiator for the refrigerant, the second cascade flow path functions as a radiator for the second refrigerant, and the second heat exchanger functions as an evaporator for the second refrigerant.

In this refrigeration cycle device, the operating efficiency of the heating operation can be enhanced by performing the dual refrigeration cycle.

A refrigeration cycle device according to an eighth aspect is the refrigeration cycle device according to the seventh aspect, wherein the first refrigerant circuit further includes a third heat exchanger. The refrigeration cycle device is capable of cooling operation in which the third heat exchanger functions as a radiator for the first refrigerant and the first heat exchanger functions as an evaporator for the first refrigerant.

In this refrigeration cycle device, cooling operation can be performed by a unitary cycle.

A refrigeration cycle device according to a ninth aspect is the refrigeration cycle device according to the seventh aspect, wherein the first refrigerant circuit further includes a third heat exchanger. The refrigeration cycle apparatus is capable of heating operation in which the third heat exchanger functions as an evaporator for the first refrigerant and the first heat exchanger functions as a radiator for the first refrigerant.

In this refrigeration cycle apparatus, heating operation can be performed by a unit cycle.

A refrigeration cycle device according to a tenth aspect is the refrigeration cycle device according to the seventh aspect, wherein the first refrigerant circuit further includes a third heat exchanger and a switching unit for switching the flow path of the first refrigerant. there is In the refrigeration cycle device, by switching the switching unit, the cooling operation in which the third heat exchanger functions as a radiator for the first refrigerant and the first heat exchanger functions as an evaporator for the first refrigerant, and the third heat exchange a heating operation in which the first heat exchanger functions as a radiator for the first refrigerant while the first heat exchanger functions as an evaporator for the first refrigerant.

In this refrigerating cycle device, it is possible to switch between a heating operation by a unitary refrigerating cycle and a heating operation by a dual refrigerating cycle.

A refrigerating cycle device according to an eleventh aspect is the refrigerating cycle device according to any one of the eighth aspect to the tenth aspect, further comprising a first air blower. The second heat exchanger causes heat exchange between the air flowing outside and the second refrigerant flowing inside. The third heat exchanger causes heat exchange between the air flowing outside and the first refrigerant flowing inside. The first blower forms an air flow passing through the second heat exchanger and an air flow passing through the third heat exchanger.

In this refrigeration cycle apparatus, it is possible to perform heat exchange between the second heat exchanger and the third heat exchanger using the air flow formed by the first air blower.

A refrigerating cycle apparatus according to a twelfth aspect is the refrigerating cycle apparatus according to the eleventh aspect, wherein the second heat exchanger is arranged at a position other than downwind of the third heat exchanger in the air flow.

The second heat exchanger may be arranged on the windward side of the third heat exchanger. Also, the second heat exchanger may be arranged side by side with the third heat exchanger in a direction intersecting the air flow direction of the first air blower. The second heat exchanger and the third heat exchanger are configured so as not to overlap each other in the air flow direction on the windward side of the air flow with respect to the first blower when the first blower forms an upward air flow. may be arranged side by side in the circumferential direction.

In this refrigeration cycle device, it is possible to prevent the second refrigerant in the second heat exchanger from being warmed by the air that has passed through the third heat exchanger.

A refrigeration cycle apparatus according to a thirteenth aspect is the refrigeration cycle apparatus according to either the eleventh aspect or the twelfth aspect, wherein the second heat exchanger and the third heat exchanger are arranged apart in the air flow direction. there is

In this refrigeration cycle device, it is possible to prevent the second refrigerant in the second heat exchanger from being warmed by the heat of the third heat exchanger itself.

A refrigeration cycle device according to a fourteenth aspect is the refrigeration cycle device according to any one of the sixth to thirteenth aspects, wherein the second refrigerant circuit is provided between the discharge side of the second compressor and the second cascade flow path. It further has a fourth heat exchanger provided.

In this refrigeration cycle device, the heat of the refrigerant flowing through the fourth heat exchanger can be used to process the heating load on the user side.

A refrigeration cycle device according to a fifteenth aspect is the refrigeration cycle device according to the fourteenth aspect, further comprising a second air blower. The first heat exchanger causes heat exchange between the air flowing outside and the first refrigerant flowing inside. The fourth heat exchanger causes heat exchange between the air flowing outside and the second refrigerant flowing inside. The second blower creates an airflow that passes through both the first heat exchanger and the fourth heat exchanger.

In this refrigeration cycle device, the heating load can be processed using the heat of the refrigerant in the first heat exchanger and the fourth heat exchanger due to the air flow formed by the second air blower.

A refrigeration cycle apparatus according to a sixteenth aspect is the refrigeration cycle apparatus according to any one of the first to fifteenth aspects, wherein the first refrigerant includes at least one of R1234yf, R1234ze, and R290.

The first refrigerant may consist of only R1234yf, may consist of only R1234ze, or may consist of only R290.

This refrigeration cycle device can be operated using a refrigerant with a sufficiently low global warming potential (GWP).

A refrigeration cycle device according to a seventeenth aspect is the refrigeration cycle device according to any one of the first aspect to the sixteenth aspect, wherein the second refrigerant contains carbon dioxide.

In addition, the second refrigerant may be composed only of carbon dioxide, or may be a mixed refrigerant of carbon dioxide and another refrigerant.

This refrigeration cycle apparatus can be operated using a refrigerant having a sufficiently low ozone depletion potential (ODP) and a sufficiently low global warming potential (GWP). Further, during cooling operation, the unitary refrigeration cycle using the first refrigerant circuit is avoided by using the second refrigerant circuit through which the refrigerant containing carbon dioxide flows as the refrigerant circuit on the heat source side in the binary refrigeration cycle. is performed, it is possible to avoid a decrease in the COP due to the carbon dioxide refrigerant entering a supercritical state.

1 is an overall configuration diagram of a refrigeration cycle apparatus according to a first embodiment; FIG. 1 is a functional block configuration diagram of a refrigeration cycle device according to a first embodiment; FIG. FIG. 4 is a diagram showing how a refrigerant flows during cooling operation in the first embodiment; FIG. 4 is a diagram showing how a refrigerant flows during high-load heating operation in the first embodiment; FIG. 4 is a diagram showing how a refrigerant flows during low-load heating operation in the first embodiment; It is a whole block diagram of the refrigerating-cycle apparatus which concerns on 2nd Embodiment. It is a whole block diagram of the refrigerating-cycle apparatus which concerns on 3rd Embodiment. It is a schematic block diagram of the 1st outdoor heat exchanger and the 2nd outdoor heat exchanger of the refrigerating-cycle apparatus which concerns on 4th Embodiment. FIG. 11 is a schematic configuration diagram of a first outdoor heat exchanger and a second outdoor heat exchanger of a refrigeration cycle apparatus according to a fifth embodiment; It is a schematic block diagram of the 1st outdoor heat exchanger and the 2nd outdoor heat exchanger of the refrigerating-cycle apparatus which concerns on 6th Embodiment. It is a schematic block diagram of the 1st outdoor heat exchanger and the 2nd outdoor heat exchanger of the refrigerating-cycle apparatus which concerns on 7th Embodiment.

(1) 1st Embodiment In FIG. 1, the schematic block diagram of the refrigerating-cycle apparatus 1 which concerns on 1st Embodiment is shown. FIG. 2 shows a functional block configuration diagram of the refrigeration cycle device 1 according to the first embodiment.

The refrigerating cycle device 1 is a device used to process a heat load by performing vapor compression refrigerating cycle operation. The refrigeration cycle device 1 has a heat load circuit 90 , a first refrigerant circuit 10 , a second refrigerant circuit 20 , an outdoor fan 9 and a controller 7 .

The heat load processed by the refrigeration cycle device 1 is not particularly limited, and heat exchange may be performed with fluids such as air, water, and brine. Water flowing through the heat load circuit 90 is supplied to the heat load heat exchanger 91 to process the heat load in the heat load heat exchanger 91 . The heat load circuit 90 is a circuit in which water as a heat medium circulates, and includes a heat load heat exchanger 91, a pump 92, and a utilization heat exchanger 13 (first heat (equivalent to an exchanger), and The pump 92 circulates water in the heat load circuit 90 by being driven and controlled by the controller 7 to be described later. In the heat load circuit 90 , water flows through the heat load flow path 13 b of the heat utilization heat exchanger 13 . The utilization heat exchanger 13 has a utilization passage 13a through which the first refrigerant flowing through the first refrigerant circuit 10 passes, as will be described later. The water flowing through the heat load flow path 13b of the heat utilization exchanger 13 is cooled during the cooling operation and warmed during the heating operation by exchanging heat with the first refrigerant flowing through the utilization flow path 13a.

The first refrigerant circuit 10 includes a first compressor 11, a first switching mechanism 12, a utilization heat exchanger 13 (corresponding to a first heat exchanger) shared with the heat load circuit 90, and a first utilization expansion valve. 15 (corresponding to a first expansion valve), a second utilization expansion valve 16 , a cascade heat exchanger 17 shared with the second refrigerant circuit 20 , and a first outdoor heat exchanger 18 . The first refrigerant circuit 10 is filled with a first refrigerant, which is a low-pressure refrigerant, as a refrigerant. The first refrigerant is a refrigerant of 1.2 MPa or less at 30 ° C., for example, a refrigerant containing at least one of R1234yf, R1234ze, and R290. or may consist of only R290.

The first compressor 11 is a positive displacement compressor driven by a compressor motor. The compressor motor is driven by being supplied with power through an inverter device. The operating capacity of the first compressor 11 can be changed by varying the drive frequency, which is the number of revolutions of the compressor motor. A discharge side of the first compressor 11 is connected to a first switching mechanism 12 . The suction side of the first compressor 11 is connected to the gas refrigerant side outlet of the first cascade flow path 17 a of the cascade heat exchanger 17 .

The first switching mechanism 12 has a switching valve 12a and a switching valve 12b. The switching valve 12 a and the switching valve 12 b are connected in parallel with each other on the discharge side of the first compressor 11 . The switching valve 12a is connected between the discharge side of the first compressor 11 and the utilization flow path 13a of the heat utilization exchanger 13, and the suction side of the first compressor 11 and the utilization flow path 13a of the utilization heat exchanger 13. It is a three-way valve that switches between the state of connecting the The switching valve 12b connects the discharge side of the first compressor 11 and the first outdoor heat exchanger 18, and connects the suction side of the first compressor 11 and the first outdoor heat exchanger 18. It is a three-way valve that switches between .

The use flow path 13a through which the first refrigerant flowing through the first refrigerant circuit 10 passes in the use heat exchanger 13 is connected to the switching valve 12a on the gas refrigerant side. In addition, the liquid refrigerant side of the use channel 13a is connected to the first branch point A of the first refrigerant circuit 10 . The first refrigerant can cool the water flowing through the heat load circuit 90 by evaporating while flowing through the utilization flow path 13a of the utilization heat exchanger 13, and flows through the utilization flow path 13a of the utilization heat exchanger 13. This condensing can warm the water flowing through the heat load circuit 90 .

At the first branch point A, a channel extending from the liquid refrigerant side of the usage channel 13a, a channel extending from the first usage expansion valve 15 to the side opposite to the cascade heat exchanger 17 side, and a second usage expansion valve 16 is connected to a flow path extending in the opposite direction to the first outdoor heat exchanger 18 side.

The first utilization expansion valve 15 is composed of an electronic expansion valve whose opening degree can be adjusted. The first utilization expansion valve 15 is provided in the first refrigerant circuit 10 between the first branch point A and the liquid refrigerant side inlet of the first cascade flow path 17 a of the cascade heat exchanger 17 . .

The second utilization expansion valve 16 is composed of an electronic expansion valve whose opening degree can be adjusted. The second utilization expansion valve 16 is provided in the first refrigerant circuit 10 between the first branch point A and the liquid refrigerant side outlet of the first outdoor heat exchanger 18 .

The cascade heat exchanger 17 includes a first cascade flow path 17a through which the first refrigerant flowing through the first refrigerant circuit 10 passes, and a second cascade flow path 17b through which the second refrigerant flowing through the second refrigerant circuit 20 passes. and a heat exchanger for exchanging heat between the first refrigerant and the second refrigerant. In the cascade heat exchanger 17, the first cascade flow path 17a and the second cascade flow path 17b are independent of each other, and the first refrigerant and the second refrigerant do not mix. The outlet, which is the gas refrigerant side, of the first cascade flow path 17 a of the cascade heat exchanger 17 is connected to the suction side of the first compressor 11 . The liquid refrigerant side inlet of the first cascade flow path 17 a of the cascade heat exchanger 17 is connected to the first utilization expansion valve 15 .

The first outdoor heat exchanger 18 includes a plurality of heat transfer tubes and a plurality of fins joined to the plurality of heat transfer tubes. In this embodiment, the first outdoor heat exchanger 18 is arranged outdoors. The first refrigerant flowing through the first outdoor heat exchanger 18 exchanges heat with the air sent to the first outdoor heat exchanger 18, thereby functioning as a condenser or evaporator for the first refrigerant.

The outdoor fan 9 generates an air flow with outdoor air passing through both the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 .

The second refrigerant circuit 20 includes a second compressor 21, a cascade heat exchanger 17 shared with the first refrigerant circuit 10, a heat source expansion valve 26, and a second outdoor heat exchanger 23 (in the second heat exchanger equivalent) and The second refrigerant circuit 20 is filled with a second refrigerant, which is a high-pressure refrigerant, as a refrigerant. The second refrigerant is a refrigerant having a pressure of 1.5 MPa or higher at 30° C., and may be, for example, a mixed refrigerant containing carbon dioxide, or may consist of only carbon dioxide. The mixed refrigerant containing carbon dioxide may be, for example, a mixed refrigerant of carbon dioxide and R1234ze or a mixed refrigerant of carbon dioxide and R1234yf.

The second compressor 21 is a positive displacement compressor driven by a compressor motor. The compressor motor is driven by being supplied with power through an inverter device. The operating capacity of the second compressor 21 can be changed by varying the drive frequency, which is the number of revolutions of the compressor motor. The discharge side of the second compressor 21 is connected to the inlet, which is the gas refrigerant side, of the second cascade flow path 17 b of the cascade heat exchanger 17 . A suction side of the second compressor 21 is connected to a second outdoor heat exchanger 23 .

The inlet, which is the gas refrigerant side, of the second cascade flow path 17b of the cascade heat exchanger 17 is connected to the discharge side of the second compressor 21 . The liquid refrigerant side outlet of the second cascade flow path 17 b of the cascade heat exchanger 17 is connected to the heat source expansion valve 26 .

The heat source expansion valve 26 is provided in a channel between the liquid refrigerant side of the second cascade channel 17 b of the cascade heat exchanger 17 and the liquid refrigerant side of the second outdoor heat exchanger 23 .

The second outdoor heat exchanger 23 includes a plurality of heat transfer tubes and a plurality of fins joined to the plurality of heat transfer tubes. In this embodiment, the second outdoor heat exchanger 23 is arranged outdoors alongside the first outdoor heat exchanger 18 . Specifically, the second outdoor heat exchanger 23 is arranged further upwind than the first outdoor heat exchanger 18 in the direction of the air flow formed by the outdoor fan 9 . By arranging the second outdoor heat exchanger 23 and the first outdoor heat exchanger 18 apart from each other in this way, the heat of the first outdoor heat exchanger 18 is transferred to the second outdoor heat exchanger 23. is suppressed. In addition, since the second outdoor heat exchanger 23 is not arranged on the leeward side of the first outdoor heat exchanger 18, the air warmed by the first outdoor heat exchanger 18 is sent to the second outdoor heat exchanger 23. You can prevent being caught. As a result, it is possible to prevent the carbon dioxide refrigerant in the second outdoor heat exchanger 23 from being heated by the heat of the first outdoor heat exchanger 18 . The second refrigerant flowing through the second outdoor heat exchanger 23 exchanges heat with the air sent to the second outdoor heat exchanger 23, thereby functioning as an evaporator for the second refrigerant.

The controller 7 controls the operation of each device that constitutes the thermal load circuit 90 , the first refrigerant circuit 10 and the second refrigerant circuit 20 . Specifically, the controller 7 has a processor such as a CPU and memories such as a ROM and a RAM provided for control.

In the refrigeration cycle apparatus 1 described above, the controller 7 controls each device to execute the refrigeration cycle, thereby performing a cooling operation for processing the cooling load in the thermal load heat exchanger 91 and a heating load in the thermal load heat exchanger 91. A heating operation is performed to process the The heating operation includes a low-load heating operation performed when the heating load is small and a high-load heating operation performed when the heating load is large.

(1-1) Cooling operation During cooling operation, as shown in FIG. A unit refrigerating cycle is performed so as to function as a condenser for the first refrigerant, and the refrigerating cycle is not performed in the second refrigerant circuit 20 . Specifically, the switching valves 12a and 12b of the first switching mechanism 12 are switched to the connected state indicated by solid lines in FIG. is fully closed, and the degree of opening of the second utilization expansion valve 16 is controlled so that the degree of superheat of the first refrigerant sucked into the first compressor 11 satisfies a predetermined condition. Here, the rotation speed of the first compressor 11 is controlled so that the cooling load of the heat load heat exchanger 91 in the heat load circuit 90 can be processed. In the cooling operation, the operation of the second refrigerant circuit 20 is stopped by stopping the second compressor 21 .

Thereby, the first refrigerant discharged from the first compressor 11 is sent to the first outdoor heat exchanger 18 via the switching valve 12 b of the first switching mechanism 12 . The first refrigerant sent to the first outdoor heat exchanger 18 is condensed by exchanging heat with the outdoor air supplied by the outdoor fan 9 . The first refrigerant that has passed through the first outdoor heat exchanger 18 is decompressed by the second utilization expansion valve 16 , passes through the first branch point A, and is sent to the utilization flow path 13 a of the utilization heat exchanger 13 . The first refrigerant flowing through the utilization flow path 13 a of the utilization heat exchanger 13 evaporates by exchanging heat with water flowing through the heat load flow path 13 b of the utilization heat exchanger 13 of the heat load circuit 90 . The water cooled by this heat exchange is sent to the heat load heat exchanger 91 in the heat load circuit 90 to process the cooling load. The first refrigerant evaporated in the utilization flow path 13 a of the utilization heat exchanger 13 is sucked into the first compressor 11 via the switching valve 12 a of the first switching mechanism 12 .

(1-2) High-load heating operation The high-load heating operation is performed when a high-load condition is satisfied in which the heating load to be processed in the thermal load heat exchanger 91 of the thermal load circuit 90 is large. done. Although the high load condition is not particularly limited, it may be that the low load condition, which will be described later, is not satisfied.

During high-load heating operation, as shown in FIG. 4, in the first refrigerant circuit 10, the utilization heat exchanger 13 functions as a condenser for the first refrigerant, and the cascade heat exchanger 17 functions as an evaporator for the first refrigerant. In the second refrigerant circuit 20, the cascade heat exchanger 17 functions as a radiator for the second refrigerant, and the second outdoor heat exchanger 23 functions as an evaporator for the second refrigerant. refrigeration cycle. As a result, a dual refrigeration cycle is performed by the second refrigerant circuit 20 and the first refrigerant circuit 10 during high-load heating operation. Specifically, the switching valves 12a and 12b of the first switching mechanism 12 are switched to the connection state indicated by the broken lines in FIG. 4, the pump 92, the first compressor 11, the second compressor 21, and the outdoor fan 9 are driven, The second utilization expansion valve 16 is fully closed, the degree of opening of the first utilization expansion valve 15 is controlled so that the degree of superheat of the first refrigerant sucked by the first compressor 11 satisfies a predetermined condition, and the heat source expansion valve is closed. 26 is controlled so that the degree of superheat of the second refrigerant sucked into the second compressor 21 satisfies a predetermined condition. Note that the rotation speed of the first compressor 11 is controlled so that the cooling load of the heat load heat exchanger 91 in the heat load circuit 90 can be processed. In addition, the second compressor 21 is configured, for example, so that the degree of superheat of the first refrigerant sucked into the first compressor 11 through the first cascade flow path 17a in the cascade heat exchanger 17 reaches a predetermined value. Alternatively, the rotation speed is controlled so that the second refrigerant flowing through the second cascade flow path 17b in the cascade heat exchanger 17 has a predetermined pressure.

As a result, the second refrigerant discharged from the second compressor 21 is sent to the cascade heat exchanger 17 and, when flowing through the second cascade flow path 17b, heats the first refrigerant flowing through the first cascade flow path 17a. Dissipate heat by exchanging. The second refrigerant that has dissipated heat in the cascade heat exchanger 17 is decompressed in the heat source expansion valve 26, and then exchanges heat with the outdoor air supplied by the outdoor fan 9 in the second outdoor heat exchanger 23 to evaporate. 2 is sucked into the compressor 21 . The first refrigerant discharged from the first compressor 11 is sent to the utilization passage 13a of the utilization heat exchanger 13 via the switching valve 12a of the first switching mechanism 12 . The first refrigerant flowing through the utilization flow path 13 a of the utilization heat exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13 b of the utilization heat exchanger 13 of the heat load circuit 90 . The water warmed by this heat exchange is sent to the heat load heat exchanger 91 in the heat load circuit 90 to treat the heating load. The first refrigerant condensed in the utilization flow path 13 a of the utilization heat exchanger 13 passes through the first branch point A and is decompressed in the first utilization expansion valve 15 . The refrigerant decompressed by the first utilization expansion valve 15 evaporates by exchanging heat with the second refrigerant flowing through the second cascade flow path 17b when passing through the first cascade flow path 17a of the cascade heat exchanger 17. . The first refrigerant evaporated in the first cascade flow path 17 a of the cascade heat exchanger 17 is sucked into the first compressor 11 .

(1-3) Low-load heating operation The low-load heating operation is performed when the heating operation is performed when the low-load condition that the heating load to be processed in the thermal load heat exchanger 91 of the thermal load circuit 90 is small is satisfied. done.

Although the low and high load conditions are not particularly limited, for example, the heating load in the heat load heat exchanger 91 of the heat load circuit 90 can be processed even if the compression ratio of the first compressor 11 is a predetermined compression ratio or less. The condition may be that it is a load. The predetermined compression ratio here is, for example, the degree of decrease in the operating efficiency of the refrigeration cycle device 1 due to the heat exchange loss in the cascade heat exchanger 17 when performing the heating operation of the dual refrigeration cycle in the refrigeration cycle device 1. From the processing of the heating load by the heating operation of the binary refrigeration cycle in which both the first refrigerant circuit 10 and the second refrigerant circuit 20 are operated, to the processing of the heating load by the heating operation of the unitary refrigeration cycle in which only the first refrigerant circuit 10 is operated. The compression ratio of the first compressor 11 may be larger than the degree of decrease in operating efficiency in the refrigeration cycle apparatus 1 when changed. Further, the predetermined compression ratio here is, for example, the coefficient of performance (COP: The compression ratio of the first compressor 11 may be such that the coefficient of performance (COP) when processing the heating load by the unitary refrigeration cycle in which only the first refrigerant circuit 10 is operated is larger than the coefficient of performance).

Further, the low and high load condition is not limited to the condition based on the predetermined compression ratio. Alternatively, the difference between the temperature of the fluid required in the heat load heat exchanger 91 of the heat load circuit 90 and the outside air temperature may be a predetermined value or more. It may be predetermined based on the compression ratio. The threshold used for determining the low-high load condition may be determined in advance and held in the memory of the controller 7 or the like.

During low-load heating operation, as shown in FIG. Instead, the refrigeration cycle is performed so that the first outdoor heat exchanger 18 functions as an evaporator for the first refrigerant, and the operation of the second refrigerant circuit 20 is stopped. As a result, the unitary refrigeration cycle by the first refrigerant circuit 10 is performed during the low-load heating operation. Specifically, the switching valves 12a and 12b of the first switching mechanism 12 are switched to the connected state indicated by the dashed lines in FIG. is fully closed, and the degree of opening of the second utilization expansion valve 16 is controlled so that the degree of superheat of the first refrigerant sucked into the first compressor 11 satisfies a predetermined condition. The rotation speed of the first compressor 11 is controlled so that the heating load of the heat load heat exchanger 91 in the heat load circuit 90 can be processed. In addition, in the low-load heating operation, the operation of the second refrigerant circuit 20 is stopped by stopping the second compressor 21 .

As a result, the first refrigerant discharged from the first compressor 11 is sent to the utilization passage 13 a of the utilization heat exchanger 13 via the switching valve 12 a of the first switching mechanism 12 . The first refrigerant flowing through the utilization flow path 13 a of the utilization heat exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13 b of the utilization heat exchanger 13 of the heat load circuit 90 . The water warmed by this heat exchange is sent to the heat load heat exchanger 91 in the heat load circuit 90 to treat the heating load. After passing through the first branch point A, the first refrigerant condensed in the utilization flow path 13a of the utilization heat exchanger 13 does not flow into the first utilization expansion valve 15 which is in the fully closed state. The pressure is reduced at the 2-use expansion valve 16 . The refrigerant decompressed by the second utilization expansion valve 16 evaporates by exchanging heat with the air in the air flow formed by the outdoor fan 9 when passing through the first outdoor heat exchanger 18 . The first refrigerant evaporated in the first outdoor heat exchanger 18 is sucked into the first compressor 11 .

(1-4) Features of First Embodiment In the refrigeration cycle apparatus 1 of the first embodiment, the first refrigerant circuit 10 uses a first refrigerant having a sufficiently low global warming potential (GWP). In addition, the second refrigerant circuit 20 uses a second refrigerant having a sufficiently low ozone depletion potential (ODP) and a sufficiently low global warming potential (GWP). Therefore, deterioration of the global environment can be suppressed.

Further, even when a first refrigerant having a sufficiently low global warming potential (GWP) is used in the first refrigerant circuit 10, when the heating load is large, high-load heating operation is performed to reduce the heating load. It is processed. Specifically, during high-load heating operation, a dual refrigeration cycle is performed in which the second refrigerant circuit 20 is the heat source side cycle and the first refrigerant circuit 10 is the user side cycle. Compared to the case of performing a unitary refrigeration cycle using , it is easier to ensure the capacity during heating operation.

Further, in the refrigeration cycle apparatus 1 of the present embodiment, in the first refrigerant circuit 10, the first refrigerant having a temperature of 1.2 MPa or less at 30° C. is used instead of the second refrigerant having a temperature of 1.5 MPa or more at 30° C. . Therefore, the density of the first refrigerant sucked by the first compressor 11 of the first refrigerant circuit 10 can be increased, and the efficiency of the first compressor 11 can be increased. Also, the capacity of the first compressor 11 can be reduced.

Further, in the refrigeration cycle apparatus 1 of the present embodiment, the first refrigerant circuit 10 has the first outdoor heat exchanger 18 connected in parallel with the cascade heat exchanger 17 . Therefore, even when heat exchange between the first refrigerant and the second refrigerant is not performed in the cascade heat exchanger 17 because the second refrigerant circuit 20 is in a shutdown state, the first outdoor heat exchanger At 18, the first refrigerant is allowed to exchange heat with air. As a result, the first refrigerant circuit 10 can perform the refrigeration cycle even when the second refrigerant circuit 20 is in a shutdown state. Specifically, in the refrigerating cycle device 1 of the present embodiment, even when the second refrigerant circuit 20 is in a shutdown state, the first refrigerant circuit 10 is operated to perform low-load heating operation by the unitary refrigerating cycle. is possible.

Furthermore, when the heating load is small, low-load heating operation, which is a unitary refrigerating cycle using only the first refrigerant circuit 10 instead of the binary refrigerating cycle, is performed. As a result, not only can the heating load be processed while keeping the compression ratio of the first compressor 11 small, but also the loss during heat exchange between the first refrigerant and the second refrigerant in the cascade heat exchanger 17 can be suppressed. As a result, it is possible to suppress a decrease in the operating efficiency of the refrigeration cycle apparatus 1 to a small extent.

Furthermore, although carbon dioxide is used as the second refrigerant in the second refrigerant circuit 20, the unitary refrigeration cycle by the first refrigerant circuit 10 is performed instead of the second refrigerant circuit 20 during cooling operation. As a result, the pressure of the carbon dioxide refrigerant becomes critical, as in the case of performing a single refrigeration cycle using carbon dioxide refrigerant, which is a high-pressure refrigerant, or when performing a dual refrigeration cycle using carbon dioxide, which is a high-pressure refrigerant, in the heat source side cycle. Cooling operation can be performed while avoiding a situation in which the operating efficiency is lowered due to exceeding the pressure. Further, the second refrigerant circuit 20 is used only as a refrigeration cycle on the heat source side in the dual refrigeration cycle during high-load heating operation. For this reason, it is possible to manufacture the device at a low cost by lowering the pressure resistance standard required for the element parts of the second refrigerant circuit 20 in which carbon dioxide, which is a high-pressure refrigerant, is used.

Furthermore, in the refrigeration cycle apparatus 1 of the present embodiment, the second outdoor heat exchanger 23 in which the carbon dioxide refrigerant is present is arranged on the windward side of the first outdoor heat exchanger 18 in the air flow direction of the outdoor fan 9. ing. Therefore, it is possible to avoid sending air warmed by heat exchange with the first refrigerant flowing through the first outdoor heat exchanger 18 to the second outdoor heat exchanger 23 . As a result, in a state where the operation of the second refrigerant circuit 20 is stopped like during low-load heating operation, warmed air is sent to the second outdoor heat exchanger 23, and the second outdoor heat A pressure rise of the carbon dioxide refrigerant in the exchanger 23 is suppressed. In particular, when the second refrigerant circuit 20 is configured using element parts with a relatively low pressure resistance standard, the pressure increase of the carbon dioxide refrigerant in the second outdoor heat exchanger 23 tends to become a significant problem. However, even in the second refrigerant circuit 20 having a relatively low pressure resistance, in the refrigeration cycle device 1 of the present embodiment, the warmed air is not sent to the second outdoor heat exchanger 23, so the problem is suppressed.

Further, in the refrigeration cycle apparatus 1 of the present embodiment, the second outdoor heat exchanger 23 and the first outdoor heat exchanger 18 use the common outdoor fan 9, so that the fan can be shared. ing. Thus, even when the outdoor fan 9 is shared, in the refrigeration cycle apparatus 1 of the present embodiment, the second outdoor heat exchanger 23 and the first outdoor heat exchanger 18 are arranged apart from each other. Therefore, even when the operation of the second refrigerant circuit 20 is stopped, such as during low-load heating operation, the heat of the first outdoor heat exchanger 18 is suppressed from being transferred to the second outdoor heat exchanger 23. Therefore, the pressure increase of the carbon dioxide refrigerant in the second outdoor heat exchanger 23 is suppressed.

(2) Second Embodiment The refrigeration cycle apparatus 1 according to the first embodiment includes the heat load circuit 90, and the heat utilization heat exchanger 13 has the utilization flow path 13a and the heat load flow path 13b. mentioned and explained.

On the other hand, the refrigerating cycle device 1 may not include the heat load circuit 90, and the load processed by the refrigerating cycle device 1 may be an air load.

FIG. 6 shows a schematic configuration diagram of a refrigeration cycle apparatus 1a according to the second embodiment.

A refrigerating cycle apparatus 1a of the second embodiment includes, for example, a heat load fan 92a that forms an air flow instead of the pump 92 of the heat load circuit 90 of the above embodiment. The heat load fan 92a is driven and controlled by the controller 7 when the first refrigerant circuit 10 is driven.

The utilization heat exchanger 13 in the refrigeration cycle apparatus 1a of the second embodiment is used, for example, to cool or warm air in a space such as a room of a building. Specifically, in the utilization heat exchanger 13, heat is exchanged between the first refrigerant and the air by sending the air in the air-conditioned space by the heat load fan 92a.

Even in the above configuration, the same effects as in the first embodiment can be obtained.

(3) Third Embodiment In the above-described second embodiment, the refrigeration cycle apparatus 1a that includes the heat load fan 92a and processes the heat load of the air-conditioned space was described as an example.

On the other hand, as a refrigeration cycle device, for example, a refrigeration cycle device 1b dedicated to heating that processes the heating load of the air-conditioned space using the first heat utilization heat exchanger 131 and the second heat utilization heat exchanger 132 may be

FIG. 7 shows a schematic configuration diagram of a refrigeration cycle device 1b according to the third embodiment.

The refrigerating cycle device 1b according to the third embodiment is an air heat exchanger in which the first heat-utilizing heat exchanger 131 of the first refrigerant circuit 10 exchanges heat between the first refrigerant flowing inside and the air flowing outside. , and the first switching mechanism 12 is not provided. Therefore, the first utilization heat exchanger 131 functions as a radiator for the first refrigerant discharged from the first compressor 11 .

In the refrigeration cycle apparatus 1b according to the third embodiment, the second refrigerant circuit 20 has the second utilization heat exchanger 132 between the second compressor 21 and the second cascade flow path 17b of the cascade heat exchanger 17. is doing. The second heat utilization heat exchanger 132 is an air heat exchanger that exchanges heat between the second refrigerant flowing inside and the air flowing outside. It is arranged away from the first utilization heat exchanger 131 on the windward side of the air flow direction by 92a. The second utilization heat exchanger 132 functions as a radiator for the second refrigerant discharged from the second compressor 21 .

In the refrigeration cycle apparatus 1b described above, unit refrigeration cycle operation using only the first refrigerant circuit 10 is performed as the low-load heating operation. In the low-load heating operation, the first utilization expansion valve 15 is controlled to be fully closed. In the low-load heating operation, the refrigerant discharged from the first compressor 11 is condensed in the first utilization heat exchanger 131, decompressed in the second utilization expansion valve 16, and evaporated in the first outdoor heat exchanger 18. and is controlled to return to the first compressor 11 .

Further, the refrigeration cycle device 1b performs a binary refrigeration cycle using the first refrigerant circuit 10 and the second refrigerant circuit 20 in high-load heating operation. In the high-load heating operation, in the first refrigerant circuit 10, the second utilization expansion valve 16 is controlled to be fully closed. Then, in the high-load heating operation, the first refrigerant discharged from the first compressor 11 is condensed in the first utilization heat exchanger 131, decompressed in the first utilization expansion valve 15, and It is controlled to evaporate while flowing through the first cascade flow path 17 a and return to the first compressor 11 . Further, in the high-load heating operation, in the second refrigerant circuit 20, the second refrigerant discharged from the second compressor 21 releases heat when passing through the second utilization heat exchanger 132, and the cascade heat exchanger 17 When flowing through the second cascade flow path 17b, it exchanges heat with the first refrigerant flowing through the first cascade flow path 17a to further radiate heat. , is controlled to return to the second compressor 21 .

As with the first embodiment, the refrigeration cycle apparatus 1b of the third embodiment also switches the operation according to the magnitude of the heating load, thereby preventing the reduction in operating efficiency while processing the heating load. It is possible to keep it small. Furthermore, in the refrigeration cycle device 1b, the second refrigerant circuit 20 includes not only the first utilization heat exchanger 131 of the first refrigerant circuit 10, but also the second utilization heat exchanger 132, which functions as a radiator in each cycle. Since it has a heat exchanger that Here, the second utilization heat exchanger 132 is arranged on the windward side of the first utilization heat exchanger 131 in the air flow direction generated by the heat load fan 92a. As a result, even when the unitary refrigeration cycle is performed only with the first refrigerant circuit 10 while the second refrigerant circuit 20 is stopped, the air heated when passing through the first heat exchanger 131 is transferred to the second refrigerant circuit 131. It is not sent to the utilization heat exchanger 132 . Also, the first heat utilization exchanger 131 and the second heat utilization heat exchanger 132 are arranged apart from each other. Therefore, when the second refrigerant circuit 20 is stopped, the carbon dioxide refrigerant inside the second utilization heat exchanger 132 is suppressed from being heated, and the pressure inside the second refrigerant circuit 20 rises excessively. is suppressed. This makes it possible to design the second refrigerant circuit 20 to have a small pressure resistance.

(4) Fourth Embodiment In each of the embodiments described above, the refrigeration cycle apparatus in which the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are separated from each other has been described as an example.

On the other hand, in the refrigeration cycle device, the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are, for example, as shown in FIG. The heat exchanger 23 may be configured as an integrated heat exchanger. As the integrated heat exchanger, for example, a plurality of first heat transfer tubes forming the first outdoor heat exchanger 18 through which the first refrigerant flows, and a plurality of heat transfer tubes forming the second outdoor heat exchanger 23 through which the second refrigerant flows and a heat exchanger having a plurality of heat transfer fins fixed to both the first heat transfer tube and the second heat transfer tube. When configured in this way, it becomes possible to facilitate the manufacture of the device.

(5) Fifth Embodiment In each of the above embodiments, a refrigeration cycle device in which the heat exchange area in the direction of air flow between the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 is arbitrary is taken as an example. explained.

On the other hand, in the refrigeration cycle apparatus, the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are arranged in the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 in the direction of air flow by the outdoor fan 9, for example, as shown in FIG. The outdoor heat exchanger 18 and the second outdoor heat exchanger 23 have overlapping portions, and the heat exchange area of the first outdoor heat exchanger 18 is the same as that of the second outdoor heat exchanger 23 when viewed in the air flow direction. It is good also as a structure smaller than a heat exchange area.

According to this, since the ventilation resistance of the air in the first outdoor heat exchanger 18 can be kept small, more air can easily pass through the second outdoor heat exchanger 23 . This makes it easier to ensure the evaporation capacity of the second refrigerant in the second outdoor heat exchanger 23 during high-load heating operation, and to handle even a high heating load. Moreover, it is particularly effective as a refrigeration cycle apparatus that requires more heating capacity than cooling capacity.

In addition, as described in the fourth embodiment, when the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are configured as an integrated heat exchanger, the first outdoor heat exchange The amount of air passing through the second outdoor heat exchanger 23 tends to decrease as the ventilation resistance of the unit 18 increases. In this case, in particular, the effect of reducing the heat exchange area of the first outdoor heat exchanger 18 as described above is remarkably obtained.

(6) Sixth Embodiment In each of the above-described embodiments, the refrigeration cycle apparatus in which the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are arranged so as to overlap each other when viewed in the air flow direction of the outdoor fan 9 is provided. explained with an example.

On the other hand, in the refrigeration cycle apparatus, the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are, for example, as shown in FIG. The exchanger 23 is on the windward side of the outdoor fan 9 in the air flow formed by the outdoor fan 9 and may be arranged at different positions around the rotation axis of the outdoor fan 9 when viewed in the direction of the rotation axis. Here, in FIG. 10, the rotation axis direction of the outdoor fan 9 is a direction perpendicular to the paper surface. For example, in a top-blowing refrigeration cycle device in which the outdoor fan 9 takes in air from below and blows it upward, the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 may be arranged. .

Even in this case, since the air that has passed through the first outdoor heat exchanger 18 is not sent to the second outdoor heat exchanger 23, the carbon dioxide in the second outdoor heat exchanger 23 when the second refrigerant circuit 20 is stopped Heating of the coolant is suppressed.

(7) Seventh Embodiment In each of the above-described embodiments, the refrigeration cycle apparatus in which the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are arranged so as to overlap each other when viewed in the air flow direction of the outdoor fan 9 is provided. explained with an example.

On the other hand, in the refrigeration cycle device, the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are, for example, as shown in FIG. 18 and the second outdoor heat exchanger 23 may be arranged so as not to overlap each other.

In this case, for example, the second outdoor heat exchanger 23 may be arranged above the first outdoor heat exchanger 18 .

(Appendix)
Although embodiments of the present disclosure have been described above, it will be appreciated that various changes in form and detail may be made without departing from the spirit and scope of the present disclosure as set forth in the appended claims. .

1, 1a, 1b: refrigeration cycle device 9: outdoor fan (first air blower)
10: First refrigerant circuit 11: First compressor 12: First switching mechanism (switching unit)
13: Utilization heat exchanger (first heat exchanger)
13a: use channel 13b: heat load channel 15: first use expansion valve (first expansion valve)
16: Second utilization expansion valve 17: Cascade heat exchanger 17a: First cascade flow path 17b: Second cascade flow path 18: First outdoor heat exchanger (third heat exchanger)
20: Second refrigerant circuit 21: Second compressor 23: Second outdoor heat exchanger (second heat exchanger)
26: heat source expansion valve (second expansion valve)
90: Thermal load circuit 91: Thermal load heat exchanger 92: Pump 92a: Thermal load fan (second air blower)
131: First use heat exchanger (first heat exchanger)
132: Second use heat exchanger (fourth heat exchanger)

JP 2014-9829 A

Claims (17)

a first refrigerant circuit (10) using a first refrigerant of 1.2 MPa or less at 30°C;
a second refrigerant circuit (20) using a second refrigerant of 1.5 MPa or more at 30°C;
with
a binary cycle operation in which the first refrigerant circuit and the second refrigerant circuit are simultaneously operated to perform heat exchange between the first refrigerant and the second refrigerant;
a unit cycle operation in which the cooling operation or the heating operation is performed by operating the first refrigerant circuit without operating the second refrigerant circuit;
can be executed by switching
A refrigeration cycle device (1, 1a, 1b). During the two-way cycle operation, the second refrigerant flowing through the second refrigerant circuit heats the first refrigerant flowing through the first refrigerant circuit to perform the heating operation.
The refrigeration cycle apparatus according to claim 1. performing the unit cycle operation when a predetermined low load condition is satisfied;
The refrigeration cycle apparatus according to claim 1 or 2. a first cascade flow path (17a) for flowing the first refrigerant; and a second cascade flow path (17b) for flowing the second refrigerant, which is independent of the first cascade flow path. a cascade heat exchanger (17) for exchanging heat between the first refrigerant and the second refrigerant during the binary cycle operation;
The refrigeration cycle apparatus according to any one of claims 1 to 3. The first refrigerant circuit has a first compressor (11), a first heat exchanger (13, 131), a first expansion valve (15), and the first cascade flow path (17a). is doing,
The refrigeration cycle apparatus according to claim 4. The second refrigerant circuit has a second compressor (21), the second cascade flow path (17b), a second expansion valve (26), and a second heat exchanger (23). there is
The refrigeration cycle apparatus according to claim 5. During the binary cycle operation, the first cascade flow path functions as an evaporator for the first refrigerant, the first heat exchanger functions as a radiator for the first refrigerant, and the second cascade flow path functions as an evaporator for the first refrigerant. functioning as a radiator for the second refrigerant, and functioning the second heat exchanger as an evaporator for the second refrigerant;
The refrigeration cycle apparatus according to claim 6. The first refrigerant circuit further has a third heat exchanger (18),
The cooling operation is possible in which the third heat exchanger functions as a radiator for the first refrigerant and the first heat exchanger functions as an evaporator for the first refrigerant.
The refrigeration cycle apparatus according to claim 7. The first refrigerant circuit further has a third heat exchanger (18),
The heating operation in which the third heat exchanger functions as an evaporator for the first refrigerant and the first heat exchanger functions as a radiator for the first refrigerant is possible.
The refrigeration cycle apparatus according to claim 7. The first refrigerant circuit further includes a third heat exchanger (18) and a switching section (12) for switching the flow path of the first refrigerant,
the cooling operation in which the third heat exchanger functions as a radiator for the first refrigerant and the first heat exchanger functions as an evaporator for the first refrigerant by switching the switching unit; and the heating operation in which the heat exchanger functions as an evaporator for the first refrigerant while the first heat exchanger functions as a radiator for the first refrigerant.
The refrigeration cycle apparatus according to claim 7. The second heat exchanger causes heat exchange between the air flowing outside and the second refrigerant flowing inside,
The third heat exchanger causes heat exchange between the air flowing outside and the first refrigerant flowing inside,
Further comprising a first air blower (9) that forms an air flow passing through the second heat exchanger and an air flow passing through the third heat exchanger,
The refrigeration cycle apparatus according to any one of claims 8 to 10. The second heat exchanger is arranged at a position other than downwind of the third heat exchanger in the air flow,
The refrigeration cycle apparatus according to claim 11. The second heat exchanger and the third heat exchanger are arranged apart in the air flow direction,
The refrigeration cycle apparatus according to claim 11 or 12. The second refrigerant circuit further comprises a fourth heat exchanger (132) provided between the discharge side of the second compressor and the second cascade flow path,
The refrigeration cycle apparatus according to any one of claims 6 to 13. The first heat exchanger causes heat exchange between the air flowing outside and the first refrigerant flowing inside,
The fourth heat exchanger causes heat exchange between the air flowing outside and the second refrigerant flowing inside,
Further comprising a second air blower (92a) that forms an air flow that passes through both the first heat exchanger and the fourth heat exchanger,
The refrigeration cycle apparatus according to claim 14. The first refrigerant contains at least one of R1234yf, R1234ze, and R290,
The refrigeration cycle apparatus according to any one of claims 1 to 15. The second refrigerant contains carbon dioxide,
The refrigeration cycle apparatus according to any one of claims 1 to 16.

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