JP7356057B2 - Refrigeration cycle equipment - Google Patents

Description

The present invention relates to a refrigeration cycle device.

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

For example, the refrigeration cycle device described in Patent Document 1 (Japanese Unexamined Patent Publication 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, and the heat source side refrigerant It is proposed to efficiently perform a binary refrigeration cycle when both the heat source side compressor of the circuit and the utilization side compressor of the utilization side refrigerant circuit are driven.

In this refrigeration cycle device, it is desired that the operation of the refrigeration cycle device including a first refrigerant circuit and a second refrigerant circuit be made more efficient using different methods.

The refrigeration cycle device according to the first aspect includes a first refrigerant circuit using a first refrigerant and a second refrigerant circuit using a second refrigerant. The first refrigerant has a pressure of 1.2 MPa or less at 30°C. The second refrigerant has a pressure of 1.5 MPa or more at 30°C. The refrigeration cycle device can switch between dual cycle operation and single cycle operation. In the dual cycle operation, the first refrigerant circuit and the second refrigerant circuit are operated simultaneously to perform heat exchange between the first refrigerant and the second refrigerant. In the single cycle operation, the first refrigerant circuit is operated without operating the second refrigerant circuit to perform cooling operation or heating operation.

Note that it may be a refrigeration cycle device that only performs either cooling operation or heating operation as a unit cycle operation, or it may be a refrigeration cycle device that selectively performs both cooling operation and heating operation as a unit cycle operation. good.

Further, the first refrigerant circuit and the second refrigerant circuit may be mutually independent refrigerant circuits, and the first refrigerant and the second refrigerant may not mix.

In addition, when performing a binary refrigeration cycle with a 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 usage side. Specifically, the first refrigerant circuit may handle heat load.

Note that on the user side, the heat load of air may be processed, or the heat load of fluids such as water and brine may be processed.

This refrigeration cycle device runs 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 binary refrigeration cycle including a refrigeration cycle in the second refrigerant circuit used, it is easy to ensure capacity while improving operational efficiency. In addition, in this refrigeration cycle device, for example, when the heating load is small during heating operation, instead of performing a binary refrigeration cycle, the first refrigerant circuit is operated without operating the second refrigerant circuit, and heating operation is performed. By doing so, it is possible to avoid loss caused by heat exchange between the first refrigerant and the second refrigerant during low load, and to suppress a decrease in operating efficiency.

In the refrigeration cycle device according to the second aspect, in the refrigeration cycle device according to the first aspect, during the dual cycle operation, the second refrigerant flowing through the second refrigerant circuit heats the first refrigerant flowing through the first refrigerant circuit. Perform heating operation.

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

In this refrigeration cycle device, operating efficiency can be increased by performing a dual refrigeration cycle during heating operation.

The refrigeration cycle device according to the third aspect performs unit cycle operation when a predetermined low load condition is satisfied in the refrigeration cycle device according to the first aspect or the second aspect.

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

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

A refrigeration cycle device according to a fourth aspect is the refrigeration cycle device according to any one of the first to third aspects, including a cascade heat exchanger. The cascade heat exchanger has a first cascade flow path through which a first refrigerant flows, and a second cascade flow path which is independent of the first cascade flow path and through which a second refrigerant flows. The cascade heat exchanger exchanges heat between a first refrigerant and a second refrigerant during dual cycle operation.

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

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

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

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

In this refrigeration cycle device, it is possible to perform a binary refrigeration cycle by operating the first compressor and the second compressor.

A refrigeration cycle device according to a seventh aspect is such that, in the refrigeration cycle device according to the sixth aspect, during the dual cycle operation, the first cascade flow path functions as an evaporator for the first refrigerant, and the first heat exchanger functions as the first refrigerant evaporator. The second cascade flow path is made to function as a radiator for the second refrigerant, and the second heat exchanger is made to function as an evaporator for the second refrigerant.

In this refrigeration cycle device, the operational efficiency of heating operation can be improved by performing a dual refrigeration cycle.

A refrigeration cycle device according to an eighth aspect is the refrigeration cycle device according to the seventh aspect, in which 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.

This refrigeration cycle device can perform cooling operation using a single cycle.

A refrigeration cycle device according to a ninth aspect is the refrigeration cycle device according to the seventh aspect, in which the first refrigerant circuit further includes a third heat exchanger. In the refrigeration cycle device, heating operation is possible 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.

This refrigeration cycle device can perform heating operation using a single cycle.

The 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 section that switches the flow path of the first refrigerant. There is. In the refrigeration cycle device, by switching the switching part, the third heat exchanger is operated as a radiator for the first refrigerant, while the first heat exchanger is operated as an evaporator for the first refrigerant, and the third heat exchanger is operated. It is possible to perform a heating operation in which the first heat exchanger is made to function as a radiator for the first refrigerant while the heat exchanger is made to function as an evaporator for the first refrigerant.

In this refrigeration cycle device, it is possible to switch between heating operation using a single refrigeration cycle and heating operation using a dual refrigeration cycle.

A refrigeration cycle device according to an eleventh aspect is the refrigeration cycle device according to any one of the eighth to tenth aspects, further including a first blowing section. The second heat exchanger performs heat exchange between the air flowing outside and the second refrigerant flowing inside. The third heat exchanger performs heat exchange between the air flowing outside and the first refrigerant flowing inside. The first air 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 device, it becomes possible to perform heat exchange in the second heat exchanger and the third heat exchanger using the air flow formed by the first blower.

A refrigeration cycle device according to a twelfth aspect is the refrigeration cycle device according to the eleventh aspect, in which the second heat exchanger is disposed at a position other than the leeward side of the third heat exchanger in the air flow.

The second heat exchanger may be placed upwind of the third heat exchanger. Moreover, the second heat exchanger may be arranged in line with the third heat exchanger in a direction intersecting the direction of air flow by the first blower. The second heat exchanger and the third heat exchanger are arranged so that they do not overlap each other in the air flow direction on the windward side of the air flow relative to the first blower when the first blower forms an upward air flow. They may be arranged side by side in the circumferential direction.

In this refrigeration cycle device, the second refrigerant in the second heat exchanger can be prevented from being warmed by the air that has passed through the third heat exchanger.

The refrigeration cycle device according to a thirteenth aspect is the refrigeration cycle device 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, the second refrigerant in the second heat exchanger can be prevented 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 between the discharge side of the second compressor and the second cascade flow path. It further includes a fourth heat exchanger provided.

In this refrigeration cycle device, it is possible to process the heating load on the user side using the heat of the refrigerant flowing through the fourth heat exchanger.

The refrigeration cycle device according to the fifteenth aspect is the refrigeration cycle device according to the fourteenth aspect, further including a second blowing section. The first heat exchanger performs heat exchange between air flowing outside and a first refrigerant flowing inside. The fourth heat exchanger performs heat exchange between the air flowing outside and the second refrigerant flowing inside. The second blower creates an air flow that passes through both the first heat exchanger and the fourth heat exchanger.

In this refrigeration cycle device, the heating load can be handled by 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 blowing section.

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

Note that the first refrigerant may be composed only of R1234yf, only R1234ze, or 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 to sixteenth aspects, wherein the second refrigerant contains carbon dioxide.

Note that 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 device can be operated using a refrigerant with sufficiently low ozone depletion potential (ODP) and global warming potential (GWP). In addition, during cooling operation, the second refrigerant circuit through which the refrigerant containing carbon dioxide flows is used as the refrigerant circuit on the heat source side in the binary refrigeration cycle, avoiding performing a binary refrigeration cycle, and the unit refrigeration cycle using the first refrigerant circuit. By doing so, it is possible to avoid a decrease in COP due to the carbon dioxide refrigerant entering a supercritical state.

FIG. 1 is an overall configuration diagram of a refrigeration cycle device according to a first embodiment. FIG. 1 is a functional block configuration diagram of a refrigeration cycle device according to a first embodiment. FIG. 3 is a diagram showing the state of refrigerant flow during cooling operation of the first embodiment. FIG. 3 is a diagram showing the state of refrigerant flow during high-load heating operation in the first embodiment. FIG. 3 is a diagram showing the state of refrigerant flow during low-load heating operation in the first embodiment. FIG. 2 is an overall configuration diagram of a refrigeration cycle device according to a second embodiment. FIG. 3 is an overall configuration diagram of a refrigeration cycle device according to a third embodiment. It is a schematic block diagram of the 1st outdoor heat exchanger and the 2nd outdoor heat exchanger of the refrigeration cycle apparatus based on 4th Embodiment. It is a schematic block diagram of the 1st outdoor heat exchanger and the 2nd outdoor heat exchanger of the refrigeration cycle apparatus based on 5th Embodiment. It is a schematic block diagram of the 1st outdoor heat exchanger and the 2nd outdoor heat exchanger of the refrigeration cycle apparatus based on 6th Embodiment. It is a schematic block diagram of the 1st outdoor heat exchanger and the 2nd outdoor heat exchanger of the refrigeration cycle apparatus based on 7th Embodiment.

(1) First Embodiment FIG. 1 shows a schematic configuration diagram of a refrigeration cycle device 1 according to a first embodiment. FIG. 2 shows a functional block configuration diagram of the refrigeration cycle device 1 according to the first embodiment.

The refrigeration cycle device 1 is a device used to process a heat load by performing vapor compression type refrigeration cycle operation. The refrigeration cycle device 1 includes 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 that the refrigeration cycle device 1 processes is not particularly limited, and may be heat exchanged with fluids such as air, water, and brine, but in the refrigeration cycle device 1 of this embodiment, The water flowing through the heat load circuit 90 is supplied to the heat load heat exchanger 91, and the heat load in the heat load heat exchanger 91 is processed. 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 exchanger 13 shared with the first refrigerant circuit 10). (equivalent to an exchanger). The pump 92 is driven and controlled by a controller 7, which will be described later, to circulate water through the heat load circuit 90. In the heat load circuit 90, water flows through the heat load flow path 13b included in the utilization heat exchanger 13. The utilization heat exchanger 13 has a utilization flow path 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 utilization heat exchanger 13 exchanges heat with the first refrigerant flowing through the utilization flow path 13a, thereby being cooled during cooling operation and warmed during heating operation.

The first refrigerant circuit 10 includes a first compressor 11, a first switching mechanism 12, a utilization heat exchanger 13 (corresponding to the first heat exchanger) shared with the thermal load circuit 90, and a first utilization expansion valve. 15 (corresponding to the first expansion valve), a second usage 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 that is a low-pressure refrigerant. The first refrigerant is a refrigerant having a temperature of 1.2 MPa or less at 30° C., for example, is a refrigerant containing at least one of R1234yf, R1234ze, and R290, and may be composed only of R1234yf or only R1234ze. or may be composed only of R290.

The first compressor 11 is a positive displacement compressor driven by a compressor motor. The compressor motor is driven by receiving electric power through an inverter device. The operating capacity of the first compressor 11 can be changed by varying the drive frequency, which is the rotation speed 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 17a of the cascade heat exchanger 17.

The first switching mechanism 12 includes a switching valve 12a and a switching valve 12b. The switching valve 12a and the switching valve 12b are connected in parallel to each other on the discharge side of the first compressor 11. The switching valve 12a connects the discharge side of the first compressor 11 and the utilization flow path 13a of the utilization heat exchanger 13, and connects the suction side of the first compressor 11 and the utilization flow path 13a of the utilization heat exchanger 13. This is a three-way valve that switches between the connection state and the connection state. The switching valve 12b has two states: a state where the discharge side of the first compressor 11 and the first outdoor heat exchanger 18 are connected, and a state where the suction side of the first compressor 11 and the first outdoor heat exchanger 18 are connected. It is a 3-way valve that switches between .

In the utilization heat exchanger 13, the utilization flow path 13a through which the first refrigerant flowing through the first refrigerant circuit 10 passes is connected on the gas refrigerant side to the switching valve 12a. Further, the liquid refrigerant side of the usage channel 13a is connected to a 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 when 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. By condensing the water, the water flowing through the thermal load circuit 90 can be warmed.

At the first branch point A, a flow path extending from the liquid refrigerant side of the usage flow path 13a, a flow path 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 to a flow path extending from the side opposite to the first outdoor heat exchanger 18 side.

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

The second utilization expansion valve 16 is constituted by 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 outlet of the first outdoor heat exchanger 18 on the liquid refrigerant side.

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. It is a heat exchanger that performs heat exchange 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 from each other, and the first refrigerant and the second refrigerant do not mix. An outlet of the first cascade flow path 17 a of the cascade heat exchanger 17 on the gas refrigerant side is connected to the suction side of the first compressor 11 . The inlet of the first cascade flow path 17 a of the cascade heat exchanger 17 on the liquid refrigerant side is connected to the first utilization expansion valve 15 .

The first outdoor heat exchanger 18 includes a plurality of heat exchanger tubes and a plurality of fins joined to the plurality of heat exchanger tubes. In this embodiment, the first outdoor heat exchanger 18 is placed outdoors. The first refrigerant flowing through the first outdoor heat exchanger 18 functions as a condenser or an evaporator for the first refrigerant by exchanging heat with the air sent to the first outdoor heat exchanger 18.

The outdoor fan 9 generates an air flow of 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 (not included in the second heat exchanger). equivalent) and. The second refrigerant circuit 20 is filled with a second refrigerant that is a high-pressure refrigerant. The second refrigerant is a refrigerant having a pressure of 1.5 MPa or more at 30° C., and may be a mixed refrigerant containing carbon dioxide, or may be composed only of 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 receiving electric power through an inverter device. The operating capacity of the second compressor 21 can be changed by varying the drive frequency, which is the rotation speed of the compressor motor. The discharge side of the second compressor 21 is connected to the inlet of the second cascade flow path 17b of the cascade heat exchanger 17, which is the gas refrigerant side. The suction side of the second compressor 21 is connected to a second outdoor heat exchanger 23.

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

The heat source expansion valve 26 is provided in a flow path between the liquid refrigerant side of the second cascade flow path 17b 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 exchanger tubes and a plurality of fins joined to the plurality of heat exchanger 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 disposed farther upwind than the first outdoor heat exchanger 18 in the direction of the air flow formed by the outdoor fan 9 . In this way, by arranging the second outdoor heat exchanger 23 and the first outdoor heat exchanger 18 apart from each other, the heat of the first outdoor heat exchanger 18 is transferred to the second outdoor heat exchanger 23. It is restrained from doing so. Furthermore, since the second outdoor heat exchanger 23 is not disposed 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 this from happening. Thereby, the carbon dioxide refrigerant in the second outdoor heat exchanger 23 can be prevented from being heated under the influence of the heat of the first outdoor heat exchanger 18. The second refrigerant flowing through the second outdoor heat exchanger 23 functions as an evaporator for the second refrigerant by exchanging heat with the air sent to the second outdoor heat exchanger 23.

The controller 7 controls the operation of each device constituting the heat load circuit 90, the first refrigerant circuit 10, and the second refrigerant circuit 20. Specifically, the controller 7 includes a processor such as a CPU provided for performing control, and a memory such as a ROM or RAM.

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

(1-1) Cooling operation During cooling operation, as shown in FIG. A unit refrigeration cycle is performed so as to function as a condenser for the first refrigerant, and a refrigeration 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 shown by solid lines in FIG. is fully closed, and the opening degree of the second usage expansion valve 16 is controlled so that the degree of superheating 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 it can handle the cooling load of the heat load heat exchanger 91 in the heat load circuit 90. Note that 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 12b of the first switching mechanism 12. The first refrigerant sent to the first outdoor heat exchanger 18 condenses by exchanging heat with outdoor air supplied by the outdoor fan 9. The first refrigerant that has passed through the first outdoor heat exchanger 18 is depressurized in the second usage expansion valve 16, passes through the first branch point A, and is sent to the usage flow path 13a of the usage heat exchanger 13. The first refrigerant flowing through the usage flow path 13a of the usage heat exchanger 13 is evaporated by exchanging heat with water flowing through the heat load flow path 13b of the usage heat exchanger 13 included in 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 the high-load condition that the heating load to be processed in the heat load heat exchanger 91 of the heat load circuit 90 is large is satisfied when performing the heating operation. It will be done. The high load condition is not particularly limited, but it may be that the low load condition described below 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 is made to function as a radiator for the second refrigerant, and the second outdoor heat exchanger 23 is made to function as an evaporator for the second refrigerant. Perform a refrigeration cycle. Thereby, during high-load heating operation, a binary refrigeration cycle is performed in the second refrigerant circuit 20 and the first refrigerant circuit 10. Specifically, the switching valves 12a and 12b of the first switching mechanism 12 are switched to the connected state shown by broken lines in FIG. 4, and the pump 92, the first compressor 11, the second compressor 21, and the outdoor fan 9 are driven. The second usage expansion valve 16 is fully closed, the opening degree of the first usage expansion valve 15 is controlled so that the degree of superheating of the first refrigerant drawn into the first compressor 11 satisfies a predetermined condition, and the heat source expansion valve The degree of opening of the valve 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 it can handle the cooling load of the heat load heat exchanger 91 in the heat load circuit 90. Further, the second compressor 21 is configured such that, for example, the degree of superheat of the first refrigerant that passes through the first cascade flow path 17a in the cascade heat exchanger 17 and is sucked into the first compressor 11 becomes 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.

Thereby, 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, the second refrigerant is heated with the first refrigerant flowing through the first cascade flow path 17a. By replacing it, heat will be dissipated. The second refrigerant that has radiated heat in the cascade heat exchanger 17 is depressurized in the heat source expansion valve 26, and then exchanges heat with outdoor air supplied by the outdoor fan 9 in the second outdoor heat exchanger 23. 2 compressor 21. The first refrigerant discharged from the first compressor 11 is sent to the utilization flow path 13a of the utilization heat exchanger 13 via the switching valve 12a of the first switching mechanism 12. The first refrigerant flowing through the usage flow path 13a of the usage heat exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13b of the usage heat exchanger 13 included in 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 process the heating load. The first refrigerant condensed in the utilization flow path 13a of the utilization heat exchanger 13 passes through the first branch point A, and then is depressurized in the first utilization expansion valve 15. The refrigerant whose pressure has been reduced by the first usage expansion valve 15 is evaporated 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 17a of the cascade heat exchanger 17 is sucked into the first compressor 11.

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

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

In addition, the low load condition is not limited to the condition based on the predetermined compression ratio, for example, the temperature of the fluid required in the heat load heat exchanger 91 of the heat load circuit 90 is equal to or higher than a predetermined value. 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 greater than or equal to a predetermined value, and these predetermined values may be equal to or greater than the above predetermined value. It may be predetermined based on the compression ratio. The threshold value used to determine the low load condition may be determined in advance and stored 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. Thereby, during the low-load heating operation, a unit refrigeration cycle is performed by the first refrigerant circuit 10. Specifically, the switching valves 12a and 12b of the first switching mechanism 12 are switched to the connected state shown by broken lines in FIG. is fully closed, and the opening degree of the second usage expansion valve 16 is controlled so that the degree of superheating 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. Note that in the low-load heating 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 utilization flow path 13a of the utilization heat exchanger 13 via the switching valve 12a of the first switching mechanism 12. The first refrigerant flowing through the usage flow path 13a of the usage heat exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13b of the usage heat exchanger 13 included in 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 process 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, and instead flows into the first utilization expansion valve 15, which is in the fully closed state. The pressure is reduced in the 2-use expansion valve 16. The refrigerant whose pressure has been reduced 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 the first embodiment In the refrigeration cycle device 1 of the first embodiment, the first refrigerant circuit 10 uses a first refrigerant having a sufficiently low global warming potential (GWP). Further, in the second refrigerant circuit 20, a second refrigerant having sufficiently low ozone depletion potential (ODP) and global warming potential (GWP) is used. Therefore, deterioration of the global environment can be suppressed.

Furthermore, even if the first refrigerant with a sufficiently low global warming potential (GWP) is used in the first refrigerant circuit 10, if 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, so that the first refrigerant, which is a low-pressure refrigerant, Compared to the case of performing a unit refrigeration cycle using

Furthermore, in the refrigeration cycle device 1 of the present embodiment, the first refrigerant having a pressure of 1.2 MPa or less at 30° C. is used in the first refrigerant circuit 10 instead of the second refrigerant having a pressure 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. Moreover, it becomes possible to reduce the capacity of the first compressor 11.

Further, in the refrigeration cycle device 1 of the present embodiment, the first refrigerant circuit 10 includes a first outdoor heat exchanger 18 connected in parallel to the cascade heat exchanger 17. Therefore, even if heat exchange between the first refrigerant and the second refrigerant in the cascade heat exchanger 17 is not performed due to the second refrigerant circuit 20 being in an operation stop state, the first outdoor heat exchanger At 18, the first refrigerant is allowed to exchange heat with air. Thereby, the first refrigerant circuit 10 can perform the refrigeration cycle even when the second refrigerant circuit 20 is in a stopped state. Specifically, in the refrigeration cycle device 1 of the present embodiment, even when the second refrigerant circuit 20 is in a stopped state, the first refrigerant circuit 10 is operated to perform low-load heating operation using a unit refrigeration cycle. It is now possible.

Furthermore, when the heating load is small, a low-load heating operation is performed, which is a unitary refrigeration cycle using only the first refrigerant circuit 10 instead of a binary refrigeration cycle. This not only makes it possible to handle the heating load while keeping the compression ratio in the first compressor 11 low, but also suppresses loss during heat exchange between the first refrigerant and the second refrigerant in the cascade heat exchanger 17. This makes it possible to suppress a decrease in operating efficiency in the refrigeration cycle device 1 to a small level.

Further, although carbon dioxide is used as the second refrigerant in the second refrigerant circuit 20, during cooling operation, the second refrigerant circuit 20 does not perform a refrigeration cycle, but performs a unit refrigeration cycle using the first refrigerant circuit 10. As a result, the pressure of the carbon dioxide refrigerant reaches a critical level, such as when performing a unit refrigeration cycle using carbon dioxide, which is a high-pressure refrigerant, or when performing a binary refrigeration cycle, which uses carbon dioxide, which is a high-pressure refrigerant, in the heat source side cycle. Cooling operation can be performed without reducing the operating efficiency 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 binary refrigeration cycle during high-load heating operation. For this reason, it becomes possible to manufacture the device at low cost by setting a lower standard of pressure resistance required for the component parts of the second refrigerant circuit 20 in which carbon dioxide, which is a high-pressure refrigerant, is used.

Furthermore, in the refrigeration cycle device 1 of the present embodiment, the second outdoor heat exchanger 23 in which carbon dioxide refrigerant exists 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, air heated by exchanging heat with the first refrigerant flowing through the first outdoor heat exchanger 18 can be prevented from being sent to the second outdoor heat exchanger 23 . As a result, when the operation of the second refrigerant circuit 20 is stopped, such as during low-load heating operation, the warmed air is sent to the second outdoor heat exchanger 23, thereby increasing the second outdoor heat exchanger 23. The increase in pressure of the carbon dioxide refrigerant in the exchanger 23 is suppressed. In particular, when the second refrigerant circuit 20 is constructed using component parts with low pressure resistance standards, 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 low pressure resistance, the refrigeration cycle device 1 of this embodiment does not cause the problem because the warmed air is not sent to the second outdoor heat exchanger 23. The occurrence of this is suppressed.

Furthermore, in the refrigeration cycle device 1 of the present embodiment, the second outdoor heat exchanger 23 and the first outdoor heat exchanger 18 use a common outdoor fan 9, making it possible to share the fan. ing. In this way, even when the outdoor fan 9 is shared, in the refrigeration cycle device 1 of this 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 device 1 according to the first embodiment described above is provided with a heat load circuit 90, and a case where the utilization heat exchanger 13 has a utilization flow path 13a and a heat load flow path 13b is taken as an example. I listed and explained.

On the other hand, the refrigeration cycle device 1 may not include the thermal load circuit 90, and the load handled by the refrigeration cycle device 1 may be an air load.

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

The refrigeration cycle device 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 while the first refrigerant circuit 10 is being driven.

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

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

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

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

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

The refrigeration cycle device 1b according to the third embodiment is an air heat exchanger in which the first utilization heat exchanger 131 of the first refrigerant circuit 10 performs heat exchange 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 device 1b according to the third embodiment, the second refrigerant circuit 20 includes a second utilization heat exchanger 132 between the second compressor 21 and the second cascade flow path 17b of the cascade heat exchanger 17. are doing. The second utilization heat exchanger 132 is an air heat exchanger that performs heat exchange between the second refrigerant flowing inside and the air flowing outside. It is disposed on the windward side in the air flow direction by 92a and away from the first utilization heat exchanger 131. The second utilization heat exchanger 132 functions as a radiator for the second refrigerant discharged from the second compressor 21.

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

In addition, the refrigeration cycle device 1b performs a binary refrigeration cycle using the first refrigerant circuit 10 and the second refrigerant circuit 20 during high-load heating operation. In the high-load heating operation, the second utilization expansion valve 16 is controlled to be fully closed in the first refrigerant circuit 10. In the high-load heating operation, the first refrigerant discharged from the first compressor 11 is condensed in the first utilization heat exchanger 131, is depressurized in the first utilization expansion valve 15, and is transferred to the first utilization heat exchanger 17. It is controlled so that it evaporates while flowing through the first cascade flow path 17a and returns to the first compressor 11. In addition, in the high-load heating operation, in the second refrigerant circuit 20, the second refrigerant discharged from the second compressor 21 radiates heat when passing through the second utilization heat exchanger 132, and is transferred to the cascade heat exchanger 17. When flowing through the second cascade flow path 17b, heat is exchanged with the first refrigerant flowing through the first cascade flow path 17a to further radiate heat, the pressure is reduced in the heat source expansion valve 26, and the heat is evaporated in the second outdoor heat exchanger 23. , and is controlled to return to the second compressor 21.

Similarly to the first embodiment, the refrigeration cycle device 1b of the third embodiment also switches its operation according to the size of the heating load, thereby preventing a decrease in operating efficiency while processing the heating load. It is possible to keep it small. Furthermore, in the refrigeration cycle device 1b, not only the first heat exchanger 131 of the first refrigerant circuit 10 but also the second heat exchanger 132 of the second refrigerant circuit 20 functions as a radiator in each cycle. Since it has a heat exchanger, it is possible to increase the heating capacity. 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 performing a unit refrigeration cycle only with the first refrigerant circuit 10 while the second refrigerant circuit 20 is stopped, the air heated when passing through the first utilization heat exchanger 131 is transferred to the second refrigerant circuit 131. It is not sent to the utilization heat exchanger 132. Further, the first heat exchanger 131 and the second heat exchanger 132 are arranged apart from each other. Therefore, when the second refrigerant circuit 20 is stopped, heating of the carbon dioxide refrigerant inside the second utilization heat exchanger 132 is suppressed, and the pressure inside the second refrigerant circuit 20 increases excessively. things are suppressed. This allows the second refrigerant circuit 20 to be designed with low pressure resistance.

(4) Fourth Embodiment In each of the above embodiments, a refrigeration cycle device in which the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are arranged apart 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 connected to each other, for example, as shown in FIG. The exchanger 23 may be configured as an integrated heat exchanger. As an integrated heat exchanger, for example, a plurality of first heat exchanger tubes through which the first refrigerant forming the first outdoor heat exchanger 18 flows, and a plurality through which the second refrigerant forming the second outdoor heat exchanger 23 flows. Examples of heat exchangers include a second heat exchanger tube and a plurality of heat transfer fins fixed to both the first heat exchanger tube and the second heat exchanger 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 is taken as an example in which the heat exchange area between the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 in the air flow direction is arbitrary. explained.

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 outdoor heat exchanger 18 and the second outdoor heat exchanger 23 have an overlapping part, and the heat exchange area of the first outdoor heat exchanger 18 is larger than that of the second outdoor heat exchanger 23 when viewed in the air flow direction. The structure may be smaller than the heat exchange area.

According to this, the ventilation resistance of the air in the first outdoor heat exchanger 18 can be suppressed to a low level, so that more air can easily pass through the second outdoor heat exchanger 23. Thereby, it is easy to ensure the evaporation capacity of the second refrigerant in the second outdoor heat exchanger 23 during high-load heating operation, and it is also easy to handle high heating loads. Moreover, it is particularly effective for refrigeration cycle devices that require more heating capacity than cooling capacity.

Note that, 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, especially the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are configured as an integrated heat exchanger. The larger the ventilation resistance of the vessel 18, the smaller the amount of air passing through the second outdoor heat exchanger 23 tends to be. In this case, in particular, the effect of reducing the heat exchange area of the first outdoor heat exchanger 18 as described above can be significantly obtained.

(6) Sixth Embodiment In each of the above embodiments, a refrigeration cycle device is provided in which the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are arranged so as to overlap when viewed in the air flow direction of the outdoor fan 9. Explained using 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 connected to each other, 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 when viewed in the direction of the rotation axis of the outdoor fan 9. Here, in FIG. 10, the rotational axis direction of the outdoor fan 9 is perpendicular to the paper surface. Note that, for example, the arrangement of the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 may be adopted in a top-blowing refrigeration cycle device in which the outdoor fan 9 takes in air from below and blows it upward. .

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 is removed when the second refrigerant circuit 20 is stopped. Heating of the refrigerant is suppressed.

(7) Seventh Embodiment In each of the above embodiments, a refrigeration cycle device is provided in which the first outdoor heat exchanger 18 and the second outdoor heat exchanger 23 are arranged so as to overlap when viewed in the air flow direction of the outdoor fan 9. Explained using 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.

(Additional note)
Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as described in the claims. .

1, 1a, 1b: Refrigeration cycle device 9: Outdoor fan (first ventilation section)
10: First refrigerant circuit 11: First compressor 12: First switching mechanism (switching section)
13: Utilized heat exchanger (first heat exchanger)
13a: Usage channel 13b: Heat load channel 15: First usage expansion valve (first expansion valve)
16: Second usage 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: Heat load circuit 91: Heat load heat exchanger 92: Pump 92a: Heat load fan (second blowing section)
131: First usage heat exchanger (first heat exchanger)
132: Second usage heat exchanger (fourth heat exchanger)

Unexamined Japanese Patent Publication No. 2014-9829

Claims (11)

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 having a pressure of 1.5 MPa or more at 30°C;
Equipped with
a dual cycle operation in which the first refrigerant circuit and the second refrigerant circuit are operated simultaneously to perform heat exchange between the first refrigerant and the second refrigerant;
a unit cycle operation in which cooling operation or heating operation is performed by operating the first refrigerant circuit without operating the second refrigerant circuit;
It is possible to execute by switching
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. and a cascade heat exchanger (17) for exchanging heat between the first refrigerant and the second refrigerant during the dual cycle operation,
The first refrigerant circuit includes a first compressor (11), a first heat exchanger (13, 131), a first expansion valve (15), the first cascade flow path (17a), and a third It has a heat exchanger (18),
The second refrigerant circuit includes a second compressor (21), a second cascade flow path (17b), a second expansion valve (26), and a second heat exchanger (23). Ori,
During the dual 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 a radiator for the first refrigerant. causing the second heat exchanger to function as a radiator for the second refrigerant, and causing the second heat exchanger to function as an evaporator for the second refrigerant;
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.
Refrigeration cycle device (1, 1a, 1b). 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 having a pressure of 1.5 MPa or more at 30°C;
Equipped with
a dual cycle operation in which the first refrigerant circuit and the second refrigerant circuit are operated simultaneously to perform heat exchange between the first refrigerant and the second refrigerant;
a unit cycle operation in which cooling operation or heating operation is performed by operating the first refrigerant circuit without operating the second refrigerant circuit;
It is possible to execute by switching
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. and a cascade heat exchanger (17) for exchanging heat between the first refrigerant and the second refrigerant during the dual cycle operation,
The first refrigerant circuit includes a first compressor (11), a first heat exchanger (13, 131), a first expansion valve (15), the first cascade flow path (17a), and a third It has a heat exchanger (18),
The second refrigerant circuit includes a second compressor (21), a second cascade flow path (17b), a second expansion valve (26), and a second heat exchanger (23). Ori,
During the dual 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 a radiator for the first refrigerant. causing the second heat exchanger to function as a radiator for the second refrigerant, and causing the second heat exchanger to function as an evaporator for the second refrigerant;
The heating operation is possible 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.
Refrigeration cycle device (1, 1a, 1b). 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 having a pressure of 1.5 MPa or more at 30°C;
Equipped with
a dual cycle operation in which the first refrigerant circuit and the second refrigerant circuit are operated simultaneously to perform heat exchange between the first refrigerant and the second refrigerant;
a unit cycle operation in which cooling operation or heating operation is performed by operating the first refrigerant circuit without operating the second refrigerant circuit;
It is possible to execute by switching
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. and a cascade heat exchanger (17) for exchanging heat between the first refrigerant and the second refrigerant during the dual cycle operation,
The first refrigerant circuit includes a first compressor (11), a first heat exchanger (13, 131), a first expansion valve (15), the first cascade flow path (17a), and a third It has a heat exchanger (18) and a switching part (12) that switches the flow path of the first refrigerant,
The second refrigerant circuit includes a second compressor (21), a second cascade flow path (17b), a second expansion valve (26), and a second heat exchanger (23). Ori,
During the dual 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 a radiator for the first refrigerant. causing the second heat exchanger to function as a radiator for the second refrigerant, and causing the second heat exchanger to function as an evaporator for the second 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; the heating operation in which the first heat exchanger functions as a radiator for the first refrigerant while causing the heat exchanger to function as an evaporator for the first refrigerant;
Refrigeration cycle device (1, 1a, 1b). The second heat exchanger performs heat exchange between the air flowing outside and the second refrigerant flowing inside,
The third heat exchanger performs heat exchange between air flowing outside and the first refrigerant flowing inside,
further comprising a first air blower (9) forming an air flow passing through the second heat exchanger and an air flow passing through the third heat exchanger;
The refrigeration cycle device according to any one of claims 1 to 3 . The second heat exchanger is located at a position other than downwind of the third heat exchanger in the air flow.
The refrigeration cycle device according to claim 4 . The second heat exchanger and the third heat exchanger are arranged apart from each other in the direction of the air flow.
The refrigeration cycle device according to claim 4 or 5 . 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 having a pressure of 1.5 MPa or more at 30°C;
Equipped with
a dual cycle operation in which the first refrigerant circuit and the second refrigerant circuit are operated simultaneously to perform heat exchange between the first refrigerant and the second refrigerant;
a unit cycle operation in which cooling operation or heating operation is performed by operating the first refrigerant circuit without operating the second refrigerant circuit;
It is possible to execute by switching
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. and a cascade heat exchanger (17) for exchanging heat between the first refrigerant and the second refrigerant during the dual cycle operation,
The first refrigerant circuit includes a first compressor (11), a first heat exchanger (13, 131), a first expansion valve (15), and the first cascade flow path (17a). and
The second refrigerant circuit includes a second compressor (21), a second cascade flow path (17b), a second expansion valve (26), a second heat exchanger (23), and a second compressor. a fourth heat exchanger (132) provided between the discharge side of the machine and the second cascade flow path,
The first heat exchanger performs heat exchange between air flowing outside and the first refrigerant flowing inside,
The fourth heat exchanger performs heat exchange between the air flowing outside and the second refrigerant flowing inside,
further comprising a second blowing section (92a) that forms an air flow passing through both the first heat exchanger and the fourth heat exchanger;
Refrigeration cycle device (1, 1a, 1b). During the dual 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 device according to any one of claims 1 to 7 . performing the unit cycle operation when a predetermined low load condition is met;
The refrigeration cycle device according to any one of claims 1 to 8 . The first refrigerant includes at least one of R1234yf, R1234ze, and R290,
The refrigeration cycle device according to any one of claims 1 to 9 . The second refrigerant includes carbon dioxide.
The refrigeration cycle device according to any one of claims 1 to 10 .

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