WO2022211076A1

WO2022211076A1 - Refrigeration cycle device

Info

Publication number: WO2022211076A1
Application number: PCT/JP2022/016796
Authority: WO
Inventors: 敦史吉見; 拓郎山田; 英二熊倉; 育弘岩田; 猛宮崎; 浩貴上田; 政貴田中; 雅樹中山; 修田中; 宏和藤野; 隆平加治
Original assignee: ダイキン工業株式会社
Priority date: 2021-03-31
Filing date: 2022-03-31
Publication date: 2022-10-06
Also published as: JP2022159195A; US20240027105A1; JP7208576B2; EP4317844A1; CN117098960A

Abstract

Provided is a refrigeration cycle device which can efficiently carry out a cooling operation and a heating operation using a low-pressure refrigerant and a high-pressure refrigerant. The refrigeration cycle device uses a first refrigerant at 30°C and at 1MPa or less, and a second refrigerant at 30°C and at 1.5MPa or more, the device carrying out a heating operation by carrying out a dual refrigeration cycle that comprises a use-side refrigeration cycle using a first refrigerant, and a heat source-side refrigeration cycle using a second refrigerant, and carries out a cooling operation by carrying out a single refrigeration cycle using the first refrigerant.

Description

refrigeration cycle equipment

　Conventionally, refrigeration cycle devices using a refrigerant with a low global warming potential (GWP) have been proposed in consideration of the global environment.

For example, in the refrigeration cycle device described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-197254), it is proposed that the refrigerant circuit is filled with a working fluid whose GWP is equal to or less than a predetermined value.

Among the low GWP refrigerants mentioned above, there are low-pressure refrigerants that are used at relatively low refrigerant pressures. Such a low-pressure refrigerant has a low heat transfer ability and cannot secure a sufficient circulation amount of the refrigerant during heating operation, making heating operation difficult or COP (Coefficient Of Performance) during heating operation. tends to be lower.

On the other hand, using a carbon dioxide refrigerant, which is a high-pressure refrigerant with a low GWP, as the refrigerant on the heat source side and using a low-pressure refrigerant as the refrigerant on the user side, a dual refrigeration cycle is used to ensure the capacity during heating operation. can be considered. However, even in this case, the critical pressure of the carbon dioxide refrigerant on the heat source side is exceeded during cooling operation, and the COP during cooling operation becomes low.

From the above, a refrigeration cycle device that can efficiently perform cooling operation and heating operation when using high-pressure refrigerant and low-pressure refrigerant is desired.

A refrigeration cycle apparatus according to a first aspect performs a heating operation by performing a dual refrigeration cycle including a user-side refrigeration cycle using a first refrigerant and a heat source-side refrigeration cycle using a second refrigerant. . The first refrigerant is 1 MPa or less at 30°C. The second refrigerant is 1.5 MPa or more at 30°C. The refrigeration cycle device performs cooling operation by performing a unit refrigeration cycle using the first refrigerant.

In this refrigeration cycle device, during heating operation, a user-side refrigeration cycle using a first refrigerant that is a low-pressure refrigerant of 1 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. are used. Since the dual refrigerating cycle including the refrigerating cycle on the heat source side is performed, it is easy to secure the heating capacity while improving the COP. Further, in this refrigerating cycle, since a unit refrigerating cycle using the first refrigerant, which is a low-pressure refrigerant of 1 MPa or less at 30° C., is performed during cooling operation, a dual refrigerating cycle using the second refrigerant in the refrigerating cycle on the heat source side. , it is possible to avoid a decrease in COP due to the second refrigerant exceeding the critical pressure. As a result, it is possible to efficiently perform the cooling operation and the heating operation when using the high-pressure refrigerant and the low-pressure refrigerant.

The refrigerating cycle device according to the second aspect includes an outdoor heat exchanger in the refrigerating cycle device according to the first aspect. The outdoor heat exchanger functions as an evaporator for the second refrigerant during heating operation, and functions as a radiator for the first refrigerant during cooling operation.

Although the outdoor heat exchanger is not particularly limited, for example, the refrigerant flowing through the outdoor heat exchanger may be heat-exchanged with the air.

With this refrigeration cycle device, it is possible to efficiently perform heating and cooling operations using an outdoor heat source.

The refrigeration cycle device according to the third aspect is the refrigeration cycle device according to the second aspect, and includes a cascade heat exchanger. The cascade heat exchanger is independent of the first cascade flow path through which the first refrigerant flows during heating operation and the first cascade flow path, and the second cascade flow path through which the second refrigerant flows during heating operation. and have A cascade heat exchanger allows heat exchange between the first refrigerant and the second refrigerant.

With this refrigeration cycle device, it is possible to increase the heat exchange efficiency between the refrigerant flowing through the refrigeration cycle on the heat source side and the refrigerant flowing through the refrigeration cycle on the user side.

The refrigeration cycle device according to the fourth aspect is the refrigeration cycle device according to the third aspect, and includes a utilization heat exchanger. In the utilization heat exchanger, the first refrigerant releases heat during heating operation. During heating operation, the first refrigerant evaporates when passing through the first cascade flow path, and heat is released when the second refrigerant passes through the second cascade flow path.

With this refrigeration cycle device, it is possible to efficiently perform heating operation using an outdoor heat source.

The refrigeration cycle device according to the fifth aspect is the refrigeration cycle device according to the fourth aspect, in which the first refrigerant evaporates in the utilization heat exchanger during cooling operation.

With this refrigeration cycle device, it is possible to efficiently perform cooling operation using an outdoor heat source.

The refrigeration cycle device according to the sixth aspect is the refrigeration cycle device according to any one of the second aspect to the fifth aspect, in which the first refrigerant can be collected in the first region other than the outdoor heat exchanger. In addition, this refrigeration cycle device can collect the second refrigerant in a second area other than the first area and outside the outdoor heat exchanger.

In this refrigeration cycle device, by collecting the first refrigerant in the first area or collecting the second refrigerant in the second area, it is possible to switch between the first refrigerant and the second refrigerant flowing through the outdoor heat exchanger. become.

A refrigeration cycle device according to a seventh aspect performs a heating operation by performing a dual refrigeration cycle including a user-side refrigeration cycle using a first refrigerant and a heat source-side refrigeration cycle using a second refrigerant. . The first refrigerant is 1 MPa or less at 30°C. The second refrigerant is 1.5 MPa or more at 30°C. The refrigeration cycle device performs cooling operation by performing a dual refrigeration cycle including a user-side refrigeration cycle using the second refrigerant and a heat source-side refrigeration cycle using the first refrigerant.

In this refrigeration cycle device, during heating operation, a user-side refrigeration cycle using a first refrigerant that is a low-pressure refrigerant of 1 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. are used. Since the dual refrigerating cycle including the refrigerating cycle on the heat source side is performed, it is easy to secure the heating capacity while improving the COP. In addition, in this refrigeration cycle, during cooling operation, a user-side refrigeration cycle using a second refrigerant that is a high-pressure refrigerant of 1.5 MPa or more at 30° C. and a first refrigerant that is a low-pressure refrigerant of 1 MPa or less at 30° C. In order to perform a binary refrigeration cycle including the refrigeration cycle on the heat source side used, COP due to the second refrigerant exceeding the critical pressure when the second refrigerant is the binary refrigeration cycle used in the refrigeration cycle on the heat source side can be avoided. As a result, it is possible to efficiently perform the cooling operation and the heating operation when using the high-pressure refrigerant and the low-pressure refrigerant.

A refrigerating cycle device according to an eighth aspect is the refrigerating cycle device according to the seventh aspect, wherein between the heating operation and the cooling operation, the refrigerant used in the refrigeration cycle on the heat source side and the refrigerant used in the refrigeration cycle on the user side and are replaced.

In this refrigeration cycle device, at least a portion of the location through which the first refrigerant flows or the location through which the second refrigerant flows during cooling operation is shared as at least a portion of the location through which the second refrigerant flows or the location through which the first refrigerant flows during heating operation. it becomes possible to

The refrigeration cycle device according to the ninth aspect is the refrigeration cycle device according to the eighth aspect, including a refrigerant tank. The coolant tank temporarily stores either the first coolant or the second coolant when replacing the coolant.

With this refrigeration cycle device, it is possible to replace the refrigerant while suppressing mixing of the first refrigerant and the second refrigerant.

A refrigeration cycle apparatus according to a tenth aspect is the refrigeration cycle apparatus according to any one of the seventh to ninth aspects, and includes a cascade heat exchanger. The cascade heat exchanger includes a first cascade flow path in which a first refrigerant evaporates during heating operation, a second cascade flow path independent of the first cascade flow path, and a second cascade flow path in which heat is released from the second refrigerant during heating operation; have A cascade heat exchanger allows heat exchange between the first refrigerant and the second refrigerant.

A refrigeration cycle apparatus according to an eleventh aspect is the refrigeration cycle apparatus according to any one of the seventh to tenth aspects, and includes a utilization heat exchanger. The utilization heat exchanger functions as a radiator for the first refrigerant during heating operation, and functions as an evaporator for the second refrigerant during cooling operation.

The utilization heat exchanger is preferably a heat exchanger that processes a heat load, and the refrigerant flowing through the utilization heat exchanger may exchange heat with air, or may exchange heat with a fluid such as brine or water. may be

In this refrigeration cycle device, heat load processing using the first refrigerant and heat load processing using the second refrigerant are possible in the utilization heat exchanger.

A refrigeration cycle apparatus according to a twelfth aspect is the refrigeration cycle apparatus according to any one of the seventh to eleventh aspects, and includes an outdoor heat exchanger. The outdoor heat exchanger functions as an evaporator for the second refrigerant during heating operation, and functions as a condenser for the first refrigerant during cooling operation.

With this refrigeration cycle device, it is possible to efficiently perform cooling operation and heating operation using an outdoor heat source.

A refrigerating cycle device according to a thirteenth aspect detects a mixed state of the first refrigerant and the second refrigerant in the refrigerating cycle device according to any one of the first to twelfth aspects.

The mixed state of the first refrigerant and the second refrigerant to be detected is not particularly limited. For example, the weight ratio of the first refrigerant in the fluid is 90% or less, or 95% or less may be detected, or that the weight ratio of the second refrigerant in the fluid has become 90% or less, or that it has become 95% or less.

The specific detection method is not particularly limited, either. For example, it may be detected based on an increase in the degree of change in the temperature of the refrigerant flowing through the heat exchanger that functions as an evaporator due to an increase in the mixing ratio.

Note that the refrigeration cycle device may notify the detection result.

With this refrigeration cycle device, it is possible to grasp the state in which the operating efficiency has decreased due to the mixing of the first refrigerant and the second refrigerant.

A refrigeration cycle device according to a fourteenth aspect separates the first refrigerant and the second refrigerant in the refrigeration cycle device according to any one of the first to thirteenth aspects.

A method for separating the first refrigerant and the second refrigerant is not particularly limited, and a known separation method can be used. For example, adsorbents having different degrees of adsorption may be used for the first refrigerant and the second refrigerant, and the refrigerant with the higher adsorption efficiency may be separated. In addition, at the location where the gas-liquid two-layer state is formed, the refrigerant with the higher purity is separated from the gas-phase refrigerant and the liquid-phase refrigerant, and the separation is performed by repeating this operation. good too. Moreover, these separations may be performed as the operation of the refrigeration cycle apparatus.

In this refrigeration cycle device, by separating the first refrigerant and the second refrigerant, it is possible to recover the operating efficiency that has decreased due to the mixing of the first refrigerant and the second refrigerant.

A refrigeration cycle device according to a fifteenth aspect is the refrigeration cycle device according to any one of the first to fourteenth aspects, wherein the first refrigerant contains at least one of R1234yf and R1234ze.

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

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

Note that the second refrigerant may be composed only of carbon dioxide.

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

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 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 functional block configuration diagram of a refrigeration cycle apparatus according to a second embodiment. FIG. 10 is a diagram showing how a refrigerant flows during cooling operation of the second embodiment; FIG. 10 is a diagram showing how a refrigerant flows during heating operation in the second embodiment; It is a whole block diagram of the refrigerating-cycle apparatus which concerns on 3rd Embodiment. It is a functional block configuration diagram of a refrigeration cycle apparatus according to a third embodiment. FIG. 11 is a diagram showing how a refrigerant flows during cooling operation in the third embodiment; FIG. 11 is a diagram showing how a refrigerant flows during heating operation in the third embodiment; It is a whole block diagram of the refrigerating-cycle apparatus which concerns on 4th Embodiment. It is a functional block block diagram of the refrigerating-cycle apparatus which concerns on 4th Embodiment. FIG. 11 is a diagram showing how a refrigerant flows during cooling operation in the fourth embodiment; FIG. 11 is a diagram showing how a refrigerant flows during heating operation in the fourth 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 refrigeration cycle device 1 is a device used to process a heat load by performing vapor compression refrigeration cycle operation. The refrigeration cycle device 1 has a heat load circuit 90 , a refrigerant circuit 10 , 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 shared with the refrigerant circuit 10. there is 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 first utilization passage 13a through which the first refrigerant flowing through the refrigerant circuit 10 passes, as will be described later. The water flowing through the heat load channel 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 first utilization channel 13a.

The refrigerant circuit 10 includes a first compressor 11, a second compressor 21, a first switching mechanism 12, a utilization heat exchanger 13 shared with the heat load circuit 90, a first expansion valve 15, a second It has an expansion valve 16 , a third expansion valve 14 , a cascade heat exchanger 17 , an outdoor heat exchanger 18 , a first on-off valve 41 and a second on-off valve 42 .

The refrigerant circuit 10 is filled with a first refrigerant, which is a low-pressure refrigerant, and a second refrigerant, which is a high-pressure refrigerant, in a substantially separated state. The first refrigerant is a refrigerant of 1 MPa or less at 30 ° C., for example, a refrigerant containing at least one of R1234yf and R1234ze. good. The second refrigerant is a refrigerant having a pressure of 1.5 MPa or more at 30° C., and may contain, for example, carbon dioxide, or may be composed of only carbon dioxide.

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 port of the first switching mechanism 12 . The suction side of the first compressor 11 is connected to the second port of the first switching mechanism 12 and the gas refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 .

The first switching mechanism 12 connects the discharge side of the first compressor 11 to the gas refrigerant side of the first utilization flow path 13 a of the heat utilization heat exchanger 13 , and connects the suction side of the first compressor 11 to the first opening/closing valve 41 . and the state of connecting to the gas refrigerant side of the first cascade flow path 17a of the cascade heat exchanger 17, the discharge side of the first compressor 11 is connected to the first on-off valve 41, and the suction side of the first compressor 11 is connected to The state of connecting to the gas refrigerant side of the first use flow path 13 a of the heat utilization heat exchanger 13 and the state of connecting to the gas refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 is switched. In this embodiment, the first switching mechanism 12 is composed of a four-way switching valve having four ports consisting of a first port, a second port, a third port, and a fourth port. A discharge side of the first compressor 11 is connected to the first port. The suction side of the first compressor 11 and the gas refrigerant side of the first cascade flow path 17a of the cascade heat exchanger 17 are connected to the second port. The gas refrigerant side of the first utilization flow path 13a of the utilization heat exchanger 13 is connected to the third port. A first on-off valve 41 is connected to the fourth port.

The gas refrigerant side of the first use flow path 13 a through which the first refrigerant flowing through the refrigerant circuit 10 passes in the use heat exchanger 13 is connected to the first switching mechanism 12 . Further, the liquid refrigerant side of the first use channel 13a is connected to the branch point A of the refrigerant circuit 10 .

At the branch point A, a channel extending from the liquid refrigerant side of the first use channel 13a, a channel extending from the first expansion valve 15 to the side opposite to the cascade heat exchanger 17 side, and the third expansion valve 14 and are connected to each other.

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

The third expansion valve 14 is composed of an electronic expansion valve whose opening degree can be adjusted. The third expansion valve 14 is provided in the middle of a flow path that connects the branch point A and the branch point B in the refrigerant circuit 10 .

At the branch point B, the flow path extending from the third expansion valve 14, the flow path extending from the second expansion valve 16, and the flow path extending from the liquid refrigerant side of the outdoor heat exchanger 18 are connected.

The second expansion valve 16 is composed of an electronic expansion valve whose opening degree can be adjusted. The second expansion valve 16 is provided between the branch point B and the liquid refrigerant side of the second cascade flow path 17 b of the cascade heat exchanger 17 in the refrigerant circuit 10 .

The cascade heat exchanger 17 includes a first cascade flow path 17a through which one of the first refrigerant and the second refrigerant passes, and a second cascade flow path through which the other of the first refrigerant and the second refrigerant passes. 17b and a cascade heat exchanger for heat exchange between the first refrigerant and the second refrigerant. In the cascade heat exchanger 17 , the first cascade flow path 17 a and the second cascade flow path 17 b are independent of each other, and the first refrigerant and the second refrigerant do not mix inside the cascade heat exchanger 17 . The gas refrigerant side of the first cascade flow path 17 a is connected to the suction side of the first compressor 11 . The liquid refrigerant side of the first cascade flow path 17 a is connected to a flow path extending from the first expansion valve 15 . The gas refrigerant side of the second cascade flow path 17 b is connected to the discharge side of the second compressor 21 . The liquid refrigerant side of the second cascade flow path 17 b is connected to a flow path extending from the second expansion valve 16 .

The outdoor heat exchanger 18 is configured with multiple heat transfer tubes and multiple fins joined to the multiple heat transfer tubes. In this embodiment, the outdoor heat exchanger 18 is arranged outdoors. The refrigerant flowing through the outdoor heat exchanger 18 exchanges heat with the air sent to the outdoor heat exchanger 18 .

The outdoor fan 9 generates an air flow by the outdoor air passing through the outdoor heat exchanger 18.

At the branch point C, a channel extending from the gas refrigerant side of the outdoor heat exchanger 18, a channel extending from the first on-off valve 41, and a channel extending from the second on-off valve 42 are connected.

The first on-off valve 41 is provided in the middle of the flow path that connects the branch point C and the fourth port of the first switching mechanism 12 .

The second on-off valve 42 is provided in the middle of the flow path that connects the branch point C and the suction side of the second compressor 21 .

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 gas refrigerant side of the second cascade flow path 17 b of the cascade heat exchanger 17 . A flow path extending from the second on-off valve 42 is connected to the suction side of the second compressor 21 .

The controller 7 controls the operation of each device that constitutes the heat load circuit 90 and the refrigerant circuit 10 . Specifically, the controller 7 has a processor as a CPU provided for control, a memory, and the like.

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, a cooling/heating transitional operation, and a heating/cooling transitional operation are performed.

(1-1) Cooling Operation During cooling operation, as shown in FIG. The second refrigerant is confined in the flow path (the flow path indicated by the dotted line) up to the expansion valve 16, and the first refrigerant is circulated through the first compressor 11, the outdoor heat exchanger 18, the third expansion valve 14, and the utilization heat exchanger 13. unit refrigerating cycle is performed. Here, the utilization heat exchanger 13 is caused to function as an evaporator for the first refrigerant, and the outdoor heat exchanger 18 is caused to function as a condenser for the first refrigerant, thereby performing a unitary refrigeration cycle using the first refrigerant. In addition, in FIG. 3 , the single arrow indicates the channel through which the first coolant flows.

Specifically, the second on-off valve 42 and the second expansion valve 16 are controlled to be fully closed, and the second refrigerant is confined in the flow path from the second on-off valve 42 to the second expansion valve 16 . Further, the connection state of the first switching mechanism 12 is switched to the connection state indicated by the solid line in FIG. 3, the pump 92, the first compressor 11, and the outdoor fan 9 are driven, and the first on-off valve 41 is controlled to open, The first expansion valve 15 is controlled to be fully closed, and the second compressor 21 is stopped. Further, the degree of opening of the third expansion valve 14 is controlled so that the degree of superheat of the first refrigerant sucked by the first compressor 11 satisfies a predetermined condition.

As a result, the first refrigerant discharged from the first compressor 11 is sent to the outdoor heat exchanger 18 via the first switching mechanism 12 and the first on-off valve 41 . The first refrigerant sent to the outdoor heat exchanger 18 is condensed by exchanging heat with the outdoor air supplied by the outdoor fan 9 . After passing through the outdoor heat exchanger 18, the first refrigerant is depressurized at the third expansion valve 14 after passing through the branch point B, passes through the branch point A, and enters the first utilization flow path 13a of the utilization heat exchanger 13. sent to The first refrigerant flowing through the first utilization channel 13a of the heat utilization exchanger 13 exchanges heat with water flowing through the heat load flow channel 13b of the heat utilization heat exchanger 13 of the heat load circuit 90, thereby evaporating. 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 first utilization flow path 13 a of the heat utilization exchanger 13 is sucked into the first compressor 11 via the first switching mechanism 12 .

(1-2) Cooling/Heating Transition Operation The refrigeration cycle apparatus 1 performs a cooling/heating transition operation for transitioning from a cycle state in which cooling operation is performed to a cycle state in which heating operation is performed.

In the cooling/heating shift operation, first, the third expansion valve 14 is controlled from the state in which the cooling operation was performed to the fully closed state, and the connection state of the first switching mechanism 12 is changed so that the discharge side of the first compressor 11 is used for heat utilization. The suction side of the first compressor 11 is connected to the first on-off valve 41 and the gas refrigerant side of the first cascade flow path 17a of the cascade heat exchanger 17. Then, the first compressor 11 is operated while the second on-off valve 42 is closed and the first expansion valve 15 and the second expansion valve 16 are fully closed. After maintaining this operating state for a while, by closing the first on-off valve 41, the flow path from the first on-off valve 41 to the third expansion valve 14 via the first compressor 11 and the utilization heat exchanger 13 is opened. to collect the first refrigerant.

Next, by opening the first expansion valve 15 while maintaining the third expansion valve 14 in a fully closed state and maintaining the first on-off valve 41 in a closed state, the first compressor 11 and the utilization heat exchanger are 13, the first expansion valve 15, and the cascade heat exchanger 17, the first refrigerant can be circulated. Also, by opening the second expansion valve 16 and opening the second on-off valve 42, the second compressor 21, the cascade heat exchanger 17, the second expansion valve 16, and the outdoor heat exchanger 18 are switched by the second refrigerant. Circulation becomes possible.

With the above, the cooling/heating shift operation ends.

(1-3) Heating Operation During heating operation, as shown in FIG. 4, a dual refrigerating cycle is performed in which the second refrigerant is used in the heat source side refrigerating cycle and the first refrigerant is used in the user side refrigerating cycle. In FIG. 4, the single arrow indicates the channel through which the first coolant flows, and the double arrow indicates the channel through which the second coolant flows. In this binary refrigerating cycle, the utilization heat exchanger 13 functions as a condenser for the first refrigerant, the cascade heat exchanger 17 functions as an evaporator for the first refrigerant, and the cascade heat exchanger 17 functions to dissipate the heat of the second refrigerant. and the outdoor heat exchanger 18 functions as an evaporator for the second refrigerant.

Specifically, in this binary refrigeration cycle, the third expansion valve 14 is controlled to be fully closed, and the first on-off valve 41 is controlled to be closed, so that the first refrigerant and the second refrigerant are mixed. 4, the pump 92, the first compressor 11, the second compressor 21, the outdoor fan 9 are driven, and the second on-off valve 42 to the open state. Furthermore, the valve opening degree of the first 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 valve opening degree of the second expansion valve 16 is controlled for the second compression. Control is performed so that the degree of superheat of the second refrigerant sucked by the machine 21 satisfies a predetermined condition.

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 second expansion valve 16, and then exchanges heat with the outdoor air supplied by the outdoor fan 9 in the outdoor heat exchanger 18 to evaporate. It is sucked into the compressor 21 . The first refrigerant discharged from the first compressor 11 is sent through the first switching mechanism 12 to the first utilization flow path 13 a of the utilization heat exchanger 13 . The first refrigerant flowing through the first use flow path 13a of the heat utilization exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13b of the heat 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 first utilization flow path 13 a of the utilization heat exchanger 13 is decompressed in the first expansion valve 15 after passing through the branch point A. When the refrigerant decompressed by the first expansion valve 15 passes through the first cascade flow path 17a of the cascade heat exchanger 17, it evaporates by exchanging heat with the second refrigerant flowing through the second cascade flow path 17b. 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 via the first switching mechanism 12 .

(1-4) Heating/Cooling Transition Operation The refrigeration cycle apparatus 1 performs a heating/cooling transition operation for transitioning from the cycle state in which the heating operation is performed to the cycle state in which the cooling operation is performed.

In the heating/cooling shift operation, first, the second expansion valve 16 is controlled to be fully closed from the state where the heating operation was performed, and the second compressor is operated while the third expansion valve 14 is also maintained in the fully closed state. 21 is driven. After maintaining this operating state for a while, by closing the second on-off valve 42 , the second compressor 21 and the second cascade flow path 17 b of the cascade heat exchanger 17 are transferred from the second on-off valve 42 . The second refrigerant can be collected in the flow path up to the expansion valve 16 .

Next, the first expansion valve 15 is controlled to be fully closed, the third expansion valve 14 and the first on-off valve 41 are opened, and the first switching mechanism 12 is closed by the first on-off valve 41 on the discharge side of the first compressor 11 . , and the suction side of the first compressor 11 is connected to the gas refrigerant side of the first use flow path 13a of the heat utilization heat exchanger 13 and the gas refrigerant side of the first cascade flow path 17a of the cascade heat exchanger 17 to As a result, the cooling operation by the unitary refrigeration cycle using the first refrigerant becomes possible.

With the above, the heating/cooling shift operation ends.

(1-5) Features of the First Embodiment In the refrigeration cycle apparatus 1 of the first embodiment, in the refrigerant circuit 10, the first refrigerant having a sufficiently low global warming potential (GWP) and the ozone depletion potential (ODP) and a second refrigerant with a sufficiently low global warming potential (GWP). Therefore, deterioration of the global environment can be suppressed.

Further, even when the first refrigerant having a sufficiently low global warming potential (GWP) is used in the refrigerant circuit 10, the second refrigerant, which is a high-pressure refrigerant, is used in the heat source side refrigeration cycle for heating operation, and the low-pressure refrigerant A binary refrigerating cycle is performed using the first refrigerant in the user-side refrigerating cycle. As a result, it is easier to secure the capacity during the heating operation compared to the case of performing the unitary refrigeration cycle using the first refrigerant, which is the low-pressure refrigerant.

Furthermore, carbon dioxide is used as the second refrigerant in the refrigerant circuit 10 . However, during cooling operation, the unitary refrigerating cycle using the second refrigerant is not performed, nor is the dual refrigerating cycle using the second refrigerant in the heat source side refrigerating cycle and the first refrigerant in the user side refrigerating cycle. A unit refrigeration cycle using one refrigerant is performed. As a result, the pressure of the carbon dioxide refrigerant becomes the critical pressure 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. The cooling operation can be performed while avoiding the COP from exceeding and becoming low. In addition, it is possible to lower the standard of pressure resistance strength required for element parts of the refrigerant circuit 10 that uses carbon dioxide, which is a high-pressure refrigerant.

(2) 2nd Embodiment In FIG. 5, the schematic block diagram of the refrigerating-cycle apparatus 1a which concerns on 2nd Embodiment is shown. FIG. 6 shows a functional block configuration diagram of a refrigeration cycle device 1a according to the second embodiment.

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

The heat load processed by the refrigeration cycle device 1a and the heat load circuit 90 are the same as in the first embodiment.

In this embodiment, the heat utilization exchanger 13 has a first utilization flow path 13a through which the first refrigerant or the second refrigerant flowing through the refrigerant circuit 10 passes, as will be described later. The water flowing through the heat load channel 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 or the second refrigerant flowing through the first utilization channel 13a.

The refrigerant circuit 10 includes a first compressor 11, a second compressor 21, a first switching mechanism 12, a second switching mechanism 22, a utilization heat exchanger 13 shared with the heat load circuit 90, and a first expansion valve 15, second expansion valve 16, cascade heat exchanger 17, outdoor heat exchanger 18, refrigerant container 19, third on-off valve 43, fourth on-off valve 44, and fifth on-off valve 45 , a sixth on-off valve 46 , a seventh on-off valve 47 , an eighth on-off valve 48 , and a ninth on-off valve 49 .

The specific configuration of the first compressor 11 itself is the same as that of the first embodiment. A discharge side of the first compressor 11 is connected to a first port of the switching valve 12 a of the first switching mechanism 12 . The suction side of the first compressor 11 is connected to the branch point D1.

At the branch point D1, the second port of the switching valve 12a of the first switching mechanism 12, the second port of the switching valve 12b of the first switching mechanism 12, and the flow path extending from the eighth on-off valve 48 are connected. It is

The first switching mechanism 12 has a switching valve 12a and a switching valve 12b.

In this embodiment, the switching valve 12a is composed of a four-way switching valve having four ports consisting of a first port, a second port, a third port, and a fourth port of the switching valve 12a. A discharge side of the first compressor 11 is connected to a first port of the switching valve 12a. A suction side of the first compressor 11 is connected to a second port of the switching valve 12a. A flow path extending from the branch point E2 is connected to the third port of the switching valve 12a. A fourth port of the switching valve 12a is connected to a first port of the switching valve 12b.

In this embodiment, the switching valve 12b is composed of a four-way switching valve having four ports consisting of a first port, a second port, a third port, and a fourth port of the switching valve 12b. A fourth port of the switching valve 12a is connected to a first port of the switching valve 12b. A second port of the switching valve 12 b is connected to the suction side of the first compressor 11 . The gas refrigerant side of the first utilization flow path 13a of the utilization heat exchanger 13 is connected to the third port of the switching valve 12b. The gas refrigerant side of the first cascade flow path 17a of the cascade heat exchanger 17 is connected to the fourth port of the switching valve 12b.

The switching valve 12a connects the discharge side of the first compressor 11 to the first port of the switching valve 12b and connects the suction side of the first compressor 11 to the branch point E2. side is connected to the branch point E2 and the suction side of the first compressor 11 is connected to the first port of the switching valve 12b.

The switching valve 12 b connects the fourth port of the switching valve 12 a to the gas refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 , and connects the suction side of the first compressor 11 to the first port of the utilization heat exchanger 13 . A state of connecting to the gas refrigerant side of the utilization flow path 13a, and a state of connecting the fourth port of the switching valve 12a to the gas refrigerant side of the first utilization flow path 13a of the heat utilization heat exchanger 13 and connecting to the suction side of the first compressor 11. is connected to the gas refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 .

The gas refrigerant side of the first use flow path 13 a through which the refrigerant flowing through the refrigerant circuit 10 passes in the use heat exchanger 13 is connected to the switching valve 12 b of the first switching mechanism 12 . Further, the liquid refrigerant side of the first use channel 13a is connected to the branch point A of the refrigerant circuit 10 .

At the branch point A, a flow path extending from the liquid refrigerant side of the first utilization flow path 13a, a flow path extending on the side opposite to the cascade heat exchanger 17 side of the first expansion valve 15, and a flow extending from the branch point J is connected to the road.

The first expansion valve 15 is composed of an electronic expansion valve whose opening degree can be adjusted. The first expansion valve 15 is provided in the middle of the flow path connecting the branch point A and the branch point F in the refrigerant circuit 10 .

The branch point F connects the flow path extending from the first expansion valve 15, the flow path extending from the branch point H1, and the flow path extending from the liquid refrigerant side in the first cascade flow path 17a of the cascade heat exchanger 17. ing.

The cascade heat exchanger 17 includes a first cascade flow path 17a through which one of the first refrigerant and the second refrigerant passes, and a second cascade flow path through which the other of the first refrigerant and the second refrigerant passes. 17b and a cascade heat exchanger for heat exchange between the first refrigerant and the second refrigerant. In the cascade heat exchanger 17 , the first cascade flow path 17 a and the second cascade flow path 17 b are independent of each other, and the first refrigerant and the second refrigerant do not mix inside the cascade heat exchanger 17 . The gas refrigerant side of the first cascade flow path 17 a is connected to the switching valve 12 b of the first switching mechanism 12 . The liquid refrigerant side of the first cascade channel 17a is connected to a channel extending from the branch point F. As shown in FIG. The gas refrigerant side of the second cascade flow path 17 b is connected to the switching valve 22 b of the second switching mechanism 22 . The liquid refrigerant side of the second cascade channel 17b is connected to a channel extending from the branch point G. As shown in FIG.

The specific configuration of the second compressor 21 itself is the same as that of the first embodiment. A discharge side of the second compressor 21 is connected to a first port of a switching valve 22 a of the second switching mechanism 22 . The suction side of the second compressor 21 is connected to the branch point E1.

The second port of the switching valve 22a of the second switching mechanism 22, the second port of the switching valve 22b of the second switching mechanism 22, and the flow path extending from the seventh on-off valve 47 are connected to the branch point E1.

The second switching mechanism 22 has a switching valve 22a and a switching valve 22b.

In this embodiment, the switching valve 22a is composed of a four-way switching valve having four ports consisting of a first port, a second port, a third port, and a fourth port of the switching valve 22a. A discharge side of the second compressor 21 is connected to a first port of the switching valve 22a. The suction side of the second compressor 21 is connected to the second port of the switching valve 22a. A flow path extending from the branch point D2 is connected to the third port of the switching valve 22a. A fourth port of the switching valve 22a is connected to a first port of the switching valve 22b.

In this embodiment, the switching valve 22b is composed of a four-way switching valve having four ports consisting of a first port, a second port, a third port, and a fourth port of the switching valve 22b. A fourth port of the switching valve 22a is connected to a first port of the switching valve 22b. A second port of the switching valve 22b is connected to the suction side of the second compressor 21 . The gas refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17 is connected to the third port of the switching valve 22b. The gas refrigerant side of the outdoor heat exchanger 18 is connected to the fourth port of the switching valve 22b.

The switching valve 22a connects the discharge side of the second compressor 21 to the first port of the switching valve 22b and connects the suction side of the second compressor 21 to the branch point D2. side is connected to the branch point D2, and the suction side of the second compressor 21 is connected to the first port of the switching valve 22b.

The switching valve 22b connects the fourth port of the switching valve 22a to the gas refrigerant side of the outdoor heat exchanger 18, and connects the suction side of the second compressor 21 to the gas refrigerant of the second cascade flow path 17b of the cascade heat exchanger 17. side, the fourth port of the switching valve 22a is connected to the gas refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17, and the suction side of the second compressor 21 is connected to the outdoor heat exchanger 18. Switches between the state of connecting to the gas refrigerant side and the state of connecting to the gas refrigerant side.

At the branch point G, a flow path extending from the liquid refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17, a flow path extending from the second expansion valve 16, and a flow path extending from the branch point H2 are connected. ing.

The second expansion valve 16 is composed of an electronic expansion valve whose opening degree can be adjusted. The second expansion valve 16 is provided between the branch point G and the liquid refrigerant side of the outdoor heat exchanger 18 .

At the branch point J, the flow path extending from the branch point A, the flow path extending from the sixth on-off valve 46, and the flow path extending from the branch point K1 are connected. The branch point K<b>1 connects the flow path extending from the branch point J, the flow path extending from the upper end portion of the refrigerant container 19 , and the flow path extending from the ninth on-off valve 49 . The ninth on-off valve 49 is provided in the middle of the flow path connecting the branch point D2 and the branch point K1. The branch point D2 connects the flow path extending from the ninth on-off valve 49, the flow path extending from the eighth on-off valve 48, and the flow path extending from the third port of the switching valve 22a of the second switching mechanism 22. there is The eighth on-off valve 48 is provided in the middle of the flow path connecting the branch point D2 and the branch point D1. The sixth on-off valve 46 is provided in the middle of the flow path connecting the branch point J and the branch point E2. The branch point E2 connects the flow path extending from the seventh on-off valve 47, the flow path extending from the sixth on-off valve 46, and the flow path extending from the third port of the switching valve 12a of the first switching mechanism 12. there is The seventh on-off valve 47 is provided in the middle of the flow path connecting the branch point E1 and the branch point E2.

The branch point K2 connects the flow path extending from the lower end of the refrigerant container 19, the flow path extending from the fourth on-off valve 44, and the flow path extending from the fifth on-off valve 45. The fourth on-off valve 44 is provided in the middle of the flow path connecting the branch point K2 and the branch point H1. The fifth on-off valve 45 is provided in the middle of the flow path connecting the branch point K2 and the branch point H2. The branch point H1 connects the flow path extending from the third on-off valve 43, the flow path extending from the fourth on-off valve 44, and the flow path extending from the branch point F. The branch point H2 connects the flow path extending from the third on-off valve 43, the flow path extending from the fifth on-off valve 45, and the flow path extending from the branch point G. The third on-off valve 43 is provided in the middle of the flow path connecting the branch point H1 and the branch point H2.

The third on-off valve 43, the fourth on-off valve 44, the fifth on-off valve 45, the sixth on-off valve 46, the seventh on-off valve 47, the eighth on-off valve 48, and the ninth on-off valve 49 are electromagnetic valves that can be controlled to switch between an open state and a closed state.

The refrigerant container 19 is a container capable of holding the first refrigerant or the second refrigerant inside. The refrigerant container 19 can be used to move the second refrigerant within the refrigerant circuit 10 while the first refrigerant is stored, or to move the first refrigerant within the refrigerant circuit 10 while the second refrigerant is stored. It has a capacity that allows storage of the first refrigerant and storage of the second refrigerant. In this embodiment, the refrigerant container 19 used to move the first refrigerant in the refrigerant circuit 10 while the second refrigerant is stored will be described as an example.

In the refrigeration cycle apparatus 1a 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, a cooling/heating transitional operation, and a heating/cooling transitional operation are performed.

(2-1) Cooling Operation During cooling operation, as shown in FIG. 7, the first refrigerant is used in the heat source side refrigerating cycle and the second refrigerant is used in the user side refrigerating cycle. In FIG. 7, the single arrow indicates the channel through which the first coolant flows, and the double arrow indicates the channel through which the second coolant flows. In this binary refrigeration cycle, the utilization heat exchanger 13 functions as an evaporator for the second refrigerant, the cascade heat exchanger 17 functions as a radiator for the second refrigerant, and the cascade heat exchanger 17 functions as an evaporator for the first refrigerant. and the outdoor heat exchanger 18 functions as a condenser for the first refrigerant.

Specifically, in this binary refrigeration cycle, the third on-off valve 43, the fourth on-off valve 44, the fifth on-off valve 45, the sixth on-off valve 46, the seventh on-off valve 47, the eighth on-off valve 48, the ninth By controlling all the on-off valves 49 to be in a closed state, mixing of the first refrigerant and the second refrigerant is prevented. Then, the connected state of the first switching mechanism 12 is switched to the connected state indicated by the solid line in FIG. 7, the connected state of the second switching mechanism 22 is switched to the connected state indicated by the solid line in FIG. , the second compressor 21 and the outdoor fan 9 are driven. Further, the valve opening degree of the first expansion valve 15 is controlled so that the degree of superheat of the second refrigerant sucked into the first compressor 11 satisfies a predetermined condition, and the valve opening degree of the second expansion valve 16 is controlled for the second compression. Control is performed so that the degree of superheat of the first refrigerant sucked by the machine 21 satisfies a predetermined condition.

As a result, the first refrigerant discharged from the second compressor 21 is sent to the outdoor heat exchanger 18 via the switching

valves

22 a and 22 b of the second switching mechanism 22 . The first refrigerant flowing through the outdoor heat exchanger 18 is condensed by exchanging heat with the outdoor air supplied by the outdoor fan 9 . The first refrigerant condensed in the outdoor heat exchanger 18 is depressurized in the second expansion valve 16 , passes through the branch point G, and is sent to the second cascade flow path 17 b of the cascade heat exchanger 17 . When the first refrigerant flows through the second cascade flow path 17b of the cascade heat exchanger 17, the first refrigerant evaporates by exchanging heat with the second refrigerant flowing through the first cascade flow path 17a. The first refrigerant evaporated in the cascade heat exchanger 17 is sucked into the second compressor 21 via the switching valve 22b of the second switching mechanism 22 . The second refrigerant discharged from the first compressor 11 is sent to the first cascade passage 17a of the cascade heat exchanger 17 via the switching valves 12a and 12b of the first switching mechanism 12 . When the second refrigerant flows through the first cascade flow path 17a of the cascade heat exchanger 17, the second refrigerant releases heat by exchanging heat with the first refrigerant flowing through the second cascade flow path 17b. The second refrigerant that has radiated heat in the cascade heat exchanger 17 passes through the branch point F, is decompressed in the first expansion valve 15, passes through the branch point A, and flows through the first utilization flow path 13a of the utilization heat exchanger 13. sent to The second refrigerant flowing through the first utilization flow path 13a of the utilization heat exchanger 13 exchanges heat with water flowing through the heat load flow path 13b of the utilization heat exchanger 13 of the heat load circuit 90, thereby evaporating. 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 second refrigerant evaporated in the first use flow path 13 a of the use heat exchanger 13 is sucked into the first compressor 11 via the switching valve 12 b of the first switching mechanism 12 .

(2-2) Cooling/heating transition operation The refrigerating cycle device 1a performs the following steps (a1) to (f1) in order to shift from the cycle state in which the cooling operation is performed to the cycle state in which the heating operation is performed. A transition operation is performed.

(a1) First, the first expansion valve 15 is controlled to a fully closed state from the state in which the cooling operation was performed, and the first compressor 11 is operated with the fourth on-off valve 44 opened. Here, the second compressor 21 and the like are operated so that the refrigeration cycle during the cooling operation using the first refrigerant is performed. As a result, the operation of collecting the second refrigerant into the refrigerant container 19 from below the refrigerant container 19 is performed. At this time, by performing control to switch the sixth on-off valve 46 between the open state and the closed state at predetermined time intervals, the gas state in the flow path from the upper end of the refrigerant container 19 to the sixth on-off valve 46 changes to the second state. Refrigerant is drawn into the first compressor 11 . Thereby, the second refrigerant can be efficiently collected into the refrigerant container 19 . This operation is continued for a predetermined time, for example, until a predetermined sufficient amount of the second refrigerant is collected in the refrigerant container 19 .

(b1) Next, the fourth on-off valve 44 is closed after the collection of the second refrigerant into the refrigerant container 19 has progressed to a predetermined amount or more. Thereafter, the switching valve 12a is switched to a state in which the discharge side of the first compressor 11 is connected to the branch point E2 and the suction side of the first compressor 11 is connected to the first port of the switching valve 12b. , the fourth port of the switching valve 12 a is connected to the gas refrigerant side of the first use flow path 13 a of the heat utilization heat exchanger 13 , and the suction side of the first compressor 11 is connected to the first cascade flow path 17 a of the cascade heat exchanger 17 . switch to the state of connecting to the gas refrigerant side of the Further, the switching valve 22a is switched to a state in which the discharge side of the second compressor 21 is connected to the first port of the switching valve 22b and the suction side of the second compressor 21 is connected to the branch point D2. , the fourth port of the switching valve 22a is connected to the gas refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17, and the suction side of the second compressor 21 is connected to the gas refrigerant side of the outdoor heat exchanger 18. switch to state. In this state, the sixth on-off valve 46 is controlled to be opened, and the first compressor 11 and the second compressor 21 are operated, whereby the second refrigerant remaining in the first cascade flow path 17a of the cascade heat exchanger 17 is is heated by the heat of the first refrigerant and driven out, and the second refrigerant is collected in the refrigerant container 19 via the first compressor 11, the branch point E2, the sixth on-off valve 46, the branch point J, and the branch point K1. After continuing this operation for a predetermined time, the sixth on-off valve 46 is controlled to be closed, and the collection of the second refrigerant into the refrigerant container 19 is finished.

(c1) Next, the switching valve 12a is switched to a state in which the discharge side of the first compressor 11 is connected to the first port of the switching valve 12b and the suction side of the first compressor 11 is connected to the branch point E2, The switching valve 12 b connects the fourth port of the switching valve 12 a to the gas refrigerant side of the first utilization flow path 13 a of the utilization heat exchanger 13 , and connects the suction side of the first compressor 11 to the first flow path of the cascade heat exchanger 17 . It is in a state of being connected to the gas refrigerant side of the cascade flow path 17a. In this state, the second expansion valve 16 is controlled to be fully closed, the fourth on-off valve 44 and the fifth on-off valve 45 are kept closed, the third on-off valve 43 is opened, and the first compressor 11 and The second compressor 21 is operated. As a result, the first refrigerant existing from the second expansion valve 16 to the suction side of the second compressor 21 is transferred to the second switching mechanism 22, the second cascade flow path 17b of the cascade heat exchanger 17, and the branch point G. , the branch point H2, the third on-off valve 43, the branch point H1, and the branch point F to the first cascade flow path 17a of the cascade heat exchanger 17. Further, the first refrigerant is sucked into the first compressor 11 via the switching valve 12b of the first switching mechanism 12. As shown in FIG. The first refrigerant discharged from the first compressor 11 is sent to the utilization heat exchanger 13 via the switching valve 12 a of the first switching mechanism 12 .

(d1) Next, the third on-off valve 43 is closed, the eighth on-off valve 48 is opened, the switching valve 22a is connected to the branch point D2 on the discharge side of the second compressor 21, and the The suction side is switched to the first port of the switching valve 22b, the switching valve 22b and the fourth port of the switching valve 22a are connected to the gas refrigerant side of the outdoor heat exchanger 18, and the suction side of the second compressor 21 is connected. side is connected to the gas refrigerant side of the second cascade flow path 17 b of the cascade heat exchanger 17 . By operating the first compressor 11 and the second compressor 21 in this state, the first refrigerant existing from the third on-off valve 43 to the suction side of the second compressor 21 is discharged from the second compressor 21. , and is drawn into the first compressor 11 via the branch point D2, the eighth on-off valve 48, and the branch point D1.

(e1) Next, the eighth on-off valve 48 is closed, the opening degree of the first expansion valve 15 is controlled while being opened, and the switching valve 12a is connected to the first port of the switching valve 12b on the discharge side of the first compressor 11. Then, the suction side of the first compressor 11 is switched to the branch point E2, and the switching valve 12b is connected to the fourth port of the switching valve 12a on the gas refrigerant side of the first cascade flow path 17a of the cascade heat exchanger 17. , and the suction side of the first compressor 11 is switched to the state of connecting to the gas refrigerant side of the first utilization flow path 13 a of the utilization heat exchanger 13 . Further, while maintaining the second expansion valve 16 in a fully closed state, the fifth on-off valve 45 is opened to connect the switching valve 22a to the first port of the switching valve 22b on the discharge side of the second compressor 21, The suction side of the second compressor 21 is switched to the state where it is connected to the branch point D2, the switching valve 22b is connected to the fourth port of the switching valve 22a, and the second compressor 21 is connected to the gas refrigerant side of the outdoor heat exchanger 18. is connected to the gas refrigerant side of the second cascade flow path 17 b of the cascade heat exchanger 17 . In this state, the first compressor 11 and the second compressor 21 are operated. As a result, the second refrigerant stored in the refrigerant container 19 is transferred to the second cascade flow path 17b of the cascade heat exchanger 17 via the branch point K2, the fifth on-off valve 45, the branch point H2, and the branch point G. Draw in. At this time, the second refrigerant flowing through the second cascade flow path 17b of the cascade heat exchanger 17 is heated by exchanging heat with the first refrigerant flowing through the first cascade flow path 17a of the cascade heat exchanger 17 . After that, the heated second refrigerant is sent to the second compressor 21 via the switching valve 22b. The second refrigerant is further discharged by the second compressor 21 and stored in the outdoor heat exchanger 18 after passing through the switching

valves

22a and 22b.

(f1) Finally, while maintaining the connected state of the second switching mechanism 22, the fifth on-off valve 45 is closed and the ninth on-off valve 49 is opened while maintaining the second expansion valve 16 in the fully closed state. The switching valve 12b connects the fourth port of the switching valve 12a to the gas refrigerant side of the first utilization flow path 13a of the utilization heat exchanger 13, and connects the suction side of the first compressor 11 to the cascade heat exchanger 17. It switches to a state of being connected to the gas refrigerant side of the first cascade flow path 17a. In this state, the second compressor 21 is operated, and the first compressor 11 is operated or stopped. As a result, the gaseous second refrigerant remaining above the refrigerant container 19 can be sucked into the second compressor 21 via the branch point K1, the ninth on-off valve 49, the branch point D2, and the switching valve 22a. . After the refrigerant container 19 is emptied by this operation, the ninth on-off valve 49 is closed.

With the above, the cooling/heating shift operation ends.

(2-3) Heating Operation During heating operation, as shown in FIG. 8, a dual refrigerating cycle is performed in which the second refrigerant is used in the heat source side refrigerating cycle and the first refrigerant is used in the user side refrigerating cycle. In FIG. 8, the single arrow indicates the channel through which the first coolant flows, and the double arrow indicates the channel through which the second coolant flows. In this binary refrigerating cycle, the utilization heat exchanger 13 functions as a condenser for the first refrigerant, the cascade heat exchanger 17 functions as an evaporator for the first refrigerant, and the cascade heat exchanger 17 functions to dissipate the heat of the second refrigerant. and the outdoor heat exchanger 18 functions as an evaporator for the second refrigerant.

Specifically, in this binary refrigeration cycle, the third on-off valve 43, the fourth on-off valve 44, the fifth on-off valve 45, the sixth on-off valve 46, the seventh on-off valve 47, the eighth on-off valve 48, the ninth By controlling all the on-off valves 49 to be in a closed state, mixing of the first refrigerant and the second refrigerant is prevented. The connection state of the switching valve 12a of the first switching mechanism 12 is set to the state indicated by the solid line in FIG. 8, the connection state of the switching valve 12b of the first switching mechanism 12 is set to the state indicated by the broken line in FIG. 8, the connection state of the switching valve 22a of the second switching mechanism 22 is switched to the connection state shown by the broken line in FIG. , the second compressor 21 and the outdoor fan 9 are driven. Furthermore, the valve opening degree of the first 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 valve opening degree of the second expansion valve 16 is controlled for the second compression. Control is performed so that the degree of superheat of the second refrigerant sucked by the machine 21 satisfies a predetermined condition.

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 second expansion valve 16, and then exchanges heat with the outdoor air supplied by the outdoor fan 9 in the outdoor heat exchanger 18 to evaporate. It is sucked into the compressor 21 . The first refrigerant discharged from the first compressor 11 is sent through the first switching mechanism 12 to the first utilization flow path 13 a of the utilization heat exchanger 13 . The first refrigerant flowing through the first use flow path 13a of the heat utilization exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13b of the heat 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 first utilization flow path 13 a of the utilization heat exchanger 13 is decompressed in the first expansion valve 15 after passing through the branch point A. The first refrigerant depressurized by the first 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. do. 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 via the first switching mechanism 12 .

(2-4) Heating/cooling shift operation The refrigerating cycle device 1a performs heating/cooling in the order of (a2) to (f2) below in order to shift from the cycle state in which the heating operation is performed to the cycle state in which the cooling operation is performed. A transition operation is performed.

(a2) First, the second expansion valve 16 is controlled to be fully closed, the fifth on-off valve 45 is controlled to be open, and the second compressor 21 is operated from the state in which the heating operation was performed. Here, the first compressor 11 and the like are operated so as to maintain the refrigeration cycle on the user side during the heating operation using the first refrigerant. As a result, the operation of collecting the second refrigerant into the refrigerant container 19 from below the refrigerant container 19 is performed. At this time, by performing control to switch the ninth on-off valve 49 between the open state and the closed state at predetermined time intervals, the gas state in the flow path from the upper end of the refrigerant container 19 to the ninth on-off valve 49 is changed to the second state. Refrigerant is drawn into the second compressor 21 . Thereby, the second refrigerant can be efficiently collected into the refrigerant container 19 . This operation is continued for a predetermined time, for example, until a predetermined sufficient amount of the second refrigerant is collected in the refrigerant container 19 .

(b2) Next, the fifth on-off valve 45 is closed after the collection of the second refrigerant into the refrigerant container 19 has progressed to a predetermined amount or more. After that, the switching valve 12a is switched to a state in which the discharge side of the first compressor 11 is connected to the first port of the switching valve 12b and the suction side of the first compressor 11 is connected to the branch point E2. , the fourth port of the switching valve 12 a is connected to the gas refrigerant side of the first cascade passage 17 a of the cascade heat exchanger 17 , and the suction side of the first compressor 11 is connected to the first utilization passage 13 a of the heat exchanger 13 . switch to the state of connecting to the gas refrigerant side of the Further, the switching valve 22a is switched to a state in which the discharge side of the second compressor 21 is connected to the branch point D2 and the suction side of the second compressor 21 is connected to the first port of the switching valve 22b. , the fourth port of the switching valve 22a is connected to the gas refrigerant side of the outdoor heat exchanger 18, and the suction side of the second compressor 21 is connected to the gas refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17. switch to state. In this state, by opening the ninth on-off valve 49 and operating the first compressor 11 and the second compressor 21, the second refrigerant remaining in the second cascade flow path 17b of the cascade heat exchanger 17 is The second refrigerant is heated by the heat of the first refrigerant and driven out, and the second refrigerant is collected in the refrigerant container 19 via the second compressor 21, the branch point D2, the ninth on-off valve 49, and the branch point K1. After continuing this operation for a predetermined time, the ninth on-off valve 49 is controlled to be closed, and the collection of the second refrigerant into the refrigerant container 19 is finished.

(c2) Next, the switching valve 22a is switched to a state in which the discharge side of the second compressor 21 is connected to the first port of the switching valve 22b and the suction side of the second compressor 21 is connected to the branch point D2, The fourth port of the switching valve 22b is connected to the gas refrigerant side of the outdoor heat exchanger 18, and the suction side of the second compressor 21 is connected to the gas refrigerant of the second cascade flow path 17b of the cascade heat exchanger 17. connected to the side. In this state, the first expansion valve 15 is controlled to be fully closed, the fourth on-off valve 44 and the fifth on-off valve 45 are kept closed, the third on-off valve 43 is opened, and the first compressor 11 and The second compressor 21 is operated. As a result, the first refrigerant existing from the first expansion valve 15 to the suction side of the first compressor 11 is transferred to the first switching mechanism 12, the first cascade flow path 17a of the cascade heat exchanger 17, and the branch point F. , the branch point H1, the third on-off valve 43, the branch point H2, and the branch point G to the second cascade flow path 17b of the cascade heat exchanger 17. Further, the first refrigerant is sucked into the second compressor 21 via the switching valve 22b of the second switching mechanism 22. As shown in FIG. Then, the first refrigerant discharged from the second compressor 21 is sent to the outdoor heat exchanger 18 via the switching valve 22 a of the second switching mechanism 22 .

(d2) Next, the third on-off valve 43 is closed, the seventh on-off valve 47 is opened, the switching valve 12a is connected to the branch point E2 on the discharge side of the first compressor 11, and the switching to a state in which the suction side is connected to the first port of the switching valve 12b, connecting the fourth port of the switching valve 12a to the gas refrigerant side of the first utilization flow path 13a of the utilization heat exchanger 13, The suction side of the first compressor 11 is switched to the state of being connected to the gas refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 . By operating the first compressor 11 and the second compressor 21 in this state, the first refrigerant existing from the third on-off valve 43 to the suction side of the first compressor 11 is discharged from the first compressor 11. , and is drawn into the second compressor 21 via the branch point E2, the seventh on-off valve 47, and the branch point E1.

(e2) Next, the seventh on-off valve 47 is closed, the opening degree of the second expansion valve 16 is controlled while being opened, and the switching valve 22a is connected to the first port of the switching valve 22b on the discharge side of the second compressor 21. Then, the suction side of the second compressor 21 is switched to the branch point D2, and the switching valve 22b is connected to the fourth port of the switching valve 22a on the gas refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17. , and the suction side of the second compressor 21 is switched to the state of connecting to the gas refrigerant side of the outdoor heat exchanger 18 . Further, while maintaining the first expansion valve 15 in a fully closed state, the fourth on-off valve 44 is opened to connect the switching valve 12a to the first port of the switching valve 12b on the discharge side of the first compressor 11, The suction side of the first compressor 11 is switched to the branch point E2, and the switching valve 12b is connected to the gas refrigerant side of the first utilization flow path 13a of the utilization heat exchanger 13 by connecting the fourth port of the switching valve 12a. Then, the state is switched to connect the suction side of the first compressor 11 to the gas refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 . In this state, the first compressor 11 and the second compressor 21 are operated. As a result, the second refrigerant stored in the refrigerant container 19 is transferred to the first cascade flow path 17a of the cascade heat exchanger 17 via the branch point K2, the fourth on-off valve 44, the branch point H1, and the branch point F. Draw in. At this time, the second refrigerant flowing through the first cascade flow path 17a of the cascade heat exchanger 17 is heated by exchanging heat with the first refrigerant flowing through the second cascade flow path 17b of the cascade heat exchanger 17 . After that, the heated second refrigerant is sent to the first compressor 11 via the switching valve 12b. The second refrigerant is further discharged by the first compressor 11 and stored in the utilization heat exchanger 13 after passing through the switching valves 12a and 12b.

(f2) Finally, while maintaining the connected state of the first switching mechanism 12, the fourth on-off valve 44 is closed and the sixth on-off valve 46 is opened while maintaining the first expansion valve 15 in the fully closed state. In this state, the first compressor 11 is operated, and the second compressor 21 is operated or stopped. As a result, the gaseous second refrigerant remaining above the refrigerant container 19 is sucked into the first compressor 11 via the branch point K1, the branch point J, the sixth on-off valve 46, the branch point E2, and the switching valve 12a. can be made After the refrigerant container 19 is emptied by this operation, the sixth on-off valve 46 is closed.

With the above, the heating/cooling shift operation ends.

(2-5) Features of Second Embodiment In the refrigeration cycle device 1a of the second embodiment, in the refrigerant circuit 10, the first refrigerant having a sufficiently low global warming potential (GWP) and the ozone depletion potential (ODP) and a second refrigerant with a sufficiently low global warming potential (GWP). Therefore, deterioration of the global environment can be suppressed.

Furthermore, carbon dioxide is used as the second refrigerant in the refrigerant circuit 10 . However, during cooling operation, the unitary refrigerating cycle using the second refrigerant is not performed, nor is the dual refrigerating cycle using the second refrigerant in the heat source side refrigerating cycle and the first refrigerant in the user side refrigerating cycle. A binary refrigerating cycle is performed in which the first refrigerant, which is a refrigerant, is used in the heat source side refrigerating cycle, and the second refrigerant, which is a high pressure refrigerant, is used in the user side refrigerating cycle. As a result, the pressure of the carbon dioxide refrigerant becomes the critical pressure 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. The cooling operation can be performed while avoiding the COP from exceeding and becoming low. In addition, it is possible to lower the standard of pressure resistance strength required for element parts of the refrigerant circuit 10 that uses carbon dioxide, which is a high-pressure refrigerant.

(3) 3rd Embodiment In FIG. 9, the schematic block diagram of the refrigerating-cycle apparatus 1b which concerns on 3rd Embodiment is shown. FIG. 10 shows a functional block configuration diagram of a refrigeration cycle device 1b according to the second embodiment.

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

The heat load processed by the refrigeration cycle device 1b and the heat load circuit 90 are the same as in the first embodiment.

The refrigerant circuit 10 includes a first compressor 11, a second compressor 21, a first switching mechanism 12, a second switching mechanism 22, a utilization heat exchanger 13 shared with the heat load circuit 90, and a first Expansion valve 15, second expansion valve 16, third expansion valve 33, fourth expansion valve 34, fifth expansion valve 35, sixth expansion valve 36, cascade heat exchanger 17, outdoor heat exchange 18, a first receiver 19a, a second receiver 19b, a tenth on-off valve 50, an eleventh on-off valve 51, a twelfth on-off valve 52, and a thirteenth on-off valve 53.

The specific configuration of the first compressor 11 itself is the same as that of the first embodiment. A discharge side of the first compressor 11 is connected to a first port of the first switching mechanism 12 . A suction side of the first compressor 11 is connected to a second port of the first switching mechanism 12 .

In this embodiment, the first switching mechanism 12 is composed of a four-way switching valve having four ports consisting of a first port, a second port, a third port, and a fourth port. A branch point P is connected to the first port of the first switching mechanism 12 . The branch point P is a flow path extending from the discharge side of the first compressor 11 , a flow path extending from the gas refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 , and the first port of the first switching mechanism 12 . and are connected to each other. A suction side of the first compressor 11 is connected to a second port of the first switching mechanism 12 . A flow path extending from the eleventh on-off valve 51 is connected to the third port of the first switching mechanism 12 . A channel extending from a tenth on-off valve 50 is connected to the fourth port of the first switching mechanism 12 .

The first switching mechanism 12 connects the branch point P to the 11th on-off valve 51 and connects the suction side of the first compressor 11 to the tenth on-off valve 50 , and connects the branch point P to the tenth on-off valve 50 . connected, and the state in which the suction side of the first compressor 11 is connected to the eleventh on-off valve 51 is switched.

The tenth on-off valve 50 is an electromagnetic valve that can be switched between an open state and a closed state. The tenth on-off valve 50 is provided in the middle of the flow path connecting the fourth port of the first switching mechanism 12 and the branch point M. As shown in FIG.

At the branch point M, a flow path extending from the tenth on-off valve 50, a flow path extending from the thirteenth on-off valve 53, a flow path extending from the gas refrigerant side of the first utilization flow path 13a of the heat utilization heat exchanger 13, is connected.

The first use channel 13a through which the refrigerant flowing through the refrigerant circuit 10 passes in the use heat exchanger 13 is connected to the channel extending from the branch point M on the gas refrigerant side. Further, the liquid refrigerant side of the first use channel 13a is connected to a channel extending from the branch point A. As shown in FIG.

At the branch point A, a flow path extending from the liquid refrigerant side of the first use flow path 13a, a flow path extending from the first expansion valve 15 on the side opposite to the branch point F side, and a flow extending from the sixth expansion valve 36 is connected to the road.

The branch point F connects the flow path extending from the first expansion valve 15, the flow path extending from the fifth expansion valve 35, and the flow path extending from the upper end of the first receiver 19a.

The first receiver 19a is a refrigerant container that stores refrigerant inside. The first receiver 19 a is provided in the middle of the flow path connecting the branch point F and the third expansion valve 33 . In addition, in this embodiment, the 1st receiver 19a stores a 2nd refrigerant|coolant.

The third expansion valve 33 is composed of an electronic expansion valve whose opening degree can be adjusted. The third expansion valve 33 is provided in the middle of the flow path that connects the lower end of the first receiver 19 a and the liquid refrigerant side of the first cascade flow path 17 a of the cascade heat exchanger 17 .

The cascade heat exchanger 17 includes a first cascade flow path 17a through which one of the first refrigerant and the second refrigerant passes, and a second cascade flow path through which the other of the first refrigerant and the second refrigerant passes. 17b and a cascade heat exchanger for heat exchange between the first refrigerant and the second refrigerant. In the cascade heat exchanger 17 , the first cascade flow path 17 a and the second cascade flow path 17 b are independent of each other, and the first refrigerant and the second refrigerant do not mix inside the cascade heat exchanger 17 . The gas refrigerant side of the first cascade flow path 17a is connected to a flow path extending from the branch point P. As shown in FIG. The liquid refrigerant side of the first cascade flow path 17 a is connected to a flow path extending from the third expansion valve 33 . The gas refrigerant side of the second cascade flow path 17 b is connected to the flow path extending from the second port of the second switching mechanism 22 and the flow path extending from the suction side of the second compressor 21 . The liquid refrigerant side of the second cascade flow path 17 b is connected to a flow path extending from the fourth expansion valve 34 .

The specific configuration of the second compressor 21 itself is the same as that of the first embodiment. A discharge side of the second compressor 21 is connected to a first port of the second switching mechanism 22 . The suction side of the second compressor 21 is connected to the second port of the second switching mechanism 22 and the gas refrigerant side of the second cascade flow path 17 b of the cascade heat exchanger 17 .

In this embodiment, the second switching mechanism 22 is composed of a four-way switching valve having four ports consisting of a first port, a second port, a third port, and a fourth port. A first port of the second switching mechanism 22 is connected to the discharge side of the second compressor 21 . A second port of the second switching mechanism 22 is connected to the suction side of the second compressor 21 and the gas refrigerant side of the second cascade flow path 17 b of the cascade heat exchanger 17 . A flow path extending from the thirteenth on-off valve 53 is connected to the third port of the second switching mechanism 22 . A channel extending from the twelfth on-off valve 52 is connected to the fourth port of the second switching mechanism 22 .

The second switching mechanism 22 connects the discharge side of the second compressor 21 to the twelfth on-off valve 52, the suction side of the second compressor 21 and the gas refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17. is connected to the thirteenth on-off valve 53, the discharge side of the second compressor 21 is connected to the thirteenth on-off valve 53, and the suction side of the second compressor 21 and the second cascade flow path of the cascade heat exchanger 17 are connected. 17 b is connected to the twelfth on-off valve 52 .

A flow path extending from the fourth expansion valve 34 is connected to the liquid refrigerant side of the second cascade flow path 17 b of the cascade heat exchanger 17 .

The fourth expansion valve 34 is composed of an electronic expansion valve whose opening degree can be adjusted. The fourth expansion valve 34 is provided between the liquid refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17 and the upper end of the second receiver 19b.

The second receiver 19b is a refrigerant container that stores refrigerant inside. The second receiver 19 b is provided in the middle of the flow path connecting the branch point G and the fourth expansion valve 34 . In addition, in this embodiment, the 2nd receiver 19b stores a 1st refrigerant|coolant.

At the branch point G, the flow path extending from the lower end of the second receiver 19b, the flow path extending from the sixth expansion valve 36, and the flow path extending from the second expansion valve 16 are connected.

The second expansion valve 16 is composed of an electronic expansion valve whose opening degree can be adjusted. The second expansion valve 16 is provided between the branch point G and the branch point B.

At the branch point B, the flow path extending from the second expansion valve 16, the flow path extending from the liquid refrigerant side of the outdoor heat exchanger 18, and the flow path extending from the fifth expansion valve 35 are connected.

The outdoor heat exchanger 18 is configured with multiple heat transfer tubes and multiple fins joined to the multiple heat transfer tubes. In this embodiment, the outdoor heat exchanger 18 is arranged outdoors. The refrigerant flowing through the outdoor heat exchanger 18 exchanges heat with the air sent to the outdoor heat exchanger 18 . The outdoor heat exchanger 18 is provided in the middle of the flow path connecting the branch point B and the branch point N. As shown in FIG.

At the branch point N, the flow path extending from the gas refrigerant side of the outdoor heat exchanger 18, the flow path extending from the 12th on-off valve 52, and the flow path extending from the 11th on-off valve 51 are connected.

The eleventh on-off valve 51 is an electromagnetic valve that can be switched between an open state and a closed state. The eleventh on-off valve 51 is provided in the middle of the flow path connecting the third port of the first switching mechanism 12 and the branch point N. As shown in FIG.

The twelfth on-off valve 52 is an electromagnetic valve that can be switched between an open state and a closed state. The twelfth on-off valve 52 is provided in the middle of the flow path that connects the fourth port of the second switching mechanism 22 and the branch point N. As shown in FIG.

The thirteenth on-off valve 53 is an electromagnetic valve that can be switched between an open state and a closed state. The thirteenth on-off valve 53 is provided in the middle of the flow path connecting the third port of the second switching mechanism 22 and the branch point M. As shown in FIG.

The fifth expansion valve 35 is composed of an electronic expansion valve whose opening degree can be adjusted. The fifth expansion valve 35 is provided in the middle of the flow path connecting the branch point F and the branch point B. As shown in FIG.

The sixth expansion valve 36 is composed of an electronic expansion valve whose opening degree can be adjusted. The sixth expansion valve 36 is provided in the middle of the flow path connecting the branch point A and the branch point G. As shown in FIG.

In the refrigeration cycle apparatus 1b 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, a cooling/heating transitional operation, and a heating/cooling transitional operation are performed.

(3-1) Cooling Operation During cooling operation, as shown in FIG. 11, a dual refrigerating cycle operation is performed using the first refrigerant in the heat source side refrigerating cycle and the second refrigerant in the user side refrigerating cycle. In FIG. 11 , single arrows indicate channels through which the first coolant flows, and double arrows indicate channels through which the second coolant flows. In this binary refrigeration cycle, the utilization heat exchanger 13 functions as an evaporator for the second refrigerant, the cascade heat exchanger 17 functions as a radiator for the second refrigerant, and the cascade heat exchanger 17 functions as an evaporator for the first refrigerant. and the outdoor heat exchanger 18 functions as a condenser for the first refrigerant.

Specifically, in this binary refrigerating cycle, all of the eleventh on-off valve 51 and the thirteenth on-off valve 53 are controlled to be closed, and the fifth expansion valve 35 and the sixth expansion valve 36 are controlled to be fully closed. This prevents the first refrigerant and the second refrigerant from being mixed. The tenth on-off valve 50 and the twelfth on-off valve 52 are controlled to be open. Then, the connected state of the first switching mechanism 12 is switched to the connected state indicated by the solid line in FIG. 11, the connected state of the second switching mechanism 22 is switched to the connected state indicated by the solid line in FIG. , the second compressor 21 and the outdoor fan 9 are driven. Further, the valve opening degree of the first expansion valve 15 is controlled so that the degree of superheat of the second refrigerant sucked into the first compressor 11 satisfies a predetermined condition, and the valve opening degree of the fourth expansion valve 34 is controlled for the second compression. Control is performed so that the degree of superheat of the first refrigerant sucked by the machine 21 satisfies a predetermined condition.

As a result, the first refrigerant discharged from the second compressor 21 is sent to the outdoor heat exchanger 18 via the second switching mechanism 22 and the twelfth on-off valve 52 . The first refrigerant flowing through the outdoor heat exchanger 18 is condensed by exchanging heat with the outdoor air supplied by the outdoor fan 9 . The first refrigerant condensed in the outdoor heat exchanger 18 passes through the second expansion valve 16 controlled to be fully open, passes through the branch point G, and flows into the second receiver 19b. The refrigerant that has flowed out of the second receiver 19 b is decompressed in the fourth expansion valve 34 and sent to the second cascade flow path 17 b of the cascade heat exchanger 17 . When the first refrigerant flows through the second cascade flow path 17b of the cascade heat exchanger 17, the first refrigerant evaporates by exchanging heat with the second refrigerant flowing through the first cascade flow path 17a. The first refrigerant evaporated in the cascade heat exchanger 17 is sucked into the second compressor 21 . The second refrigerant discharged from the first compressor 11 passes through the branch point P and is sent to the first cascade flow path 17 a of the cascade heat exchanger 17 . When the second refrigerant flows through the first cascade flow path 17a of the cascade heat exchanger 17, the second refrigerant releases heat by exchanging heat with the first refrigerant flowing through the second cascade flow path 17b. The second refrigerant that has dissipated heat in the cascade heat exchanger 17 passes through the third expansion valve 33 that is controlled to be fully open and flows into the first receiver 19a. The second refrigerant that has flowed out of the first receiver 19 a is decompressed by the first expansion valve 15 , passes through the branch point A, and is sent to the first utilization flow path 13 a of the heat utilization exchanger 13 . The second refrigerant flowing through the first utilization flow path 13a of the utilization heat exchanger 13 exchanges heat with water flowing through the heat load flow path 13b of the utilization heat exchanger 13 of the heat load circuit 90, thereby evaporating. 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 second refrigerant evaporated in the first use flow path 13 a of the heat use exchanger 13 is sucked into the first compressor 11 via the tenth on-off valve 50 and the first switching mechanism 12 .

(3-2) Cooling/heating shift operation The refrigeration cycle device 1b performs the following steps (a3) to (b3) in order to shift from the cycle state in which the cooling operation is performed to the cycle state in which the heating operation is performed. A transition operation is performed.

(a3) First, the first compressor 11 is operated while the first expansion valve 15 is controlled to be fully closed from the cooling operation state. Here, the second compressor 21 and the like are operated so that the refrigeration cycle during the cooling operation using the first refrigerant is performed. As a result, the operation of recovering the second refrigerant into the first receiver 19a from below the first receiver 19a is performed. This operation is continued for a predetermined time, for example, until a predetermined sufficient amount of the second refrigerant is collected in the first receiver 19a.

(b3) Next, the tenth on-off valve 50 is closed and the first compressor 11 is stopped in a state where the recovery of the second refrigerant to the first receiver 19a has progressed to a predetermined amount or more. After that, regarding the second switching mechanism 22 , the discharge side of the second compressor 21 is connected to the thirteenth on-off valve 53 , and the suction side of the second compressor 21 is connected to the twelfth on-off valve 52 and the second switch of the cascade heat exchanger 17 . It switches to the state of being connected to the gas refrigerant side of the cascade flow path 17b. Furthermore, the 12th on-off valve 52 and the 13th on-off valve 53 are controlled to be opened, the second expansion valve 16 and the fourth expansion valve 34 are controlled to be fully closed, and the sixth expansion valve 36 is controlled to be opened. . By operating the second compressor 21 in this state, the first refrigerant remaining in the outdoor heat exchanger 18 is heated by the heat of the air obtained from the outdoor fan 9 and driven out. Via the switching mechanism 22, the second compressor 21 is made to suck. Also, the first refrigerant remaining in the second cascade flow path 17 b of the cascade heat exchanger 17 is also sucked into the second compressor 21 . The first refrigerant discharged from the second compressor 21 is sent through the second switching mechanism 22 , the thirteenth on-off valve 53 and the branch point M to the first utilization flow path 13 a of the utilization heat exchanger 13 . Further, the first refrigerant is condensed while flowing through the first utilization channel 13a of the utilization heat exchanger 13, and flows through the branch point A and the sixth expansion valve 36 into the second receiver 19b. After this operation is continued for a predetermined time, the twelfth on-off valve 52 is controlled to be closed, and the fourth expansion valve 34 is controlled to be opened.

With the above, the cooling/heating shift operation ends.

(3-3) Heating Operation During heating operation, as shown in FIG. 12, a dual refrigerating cycle is performed in which the second refrigerant is used in the heat source side refrigerating cycle and the first refrigerant is used in the user side refrigerating cycle. In FIG. 12 , single arrows indicate channels through which the first coolant flows, and double arrows indicate channels through which the second coolant flows. In this binary refrigerating cycle, the utilization heat exchanger 13 functions as a condenser for the first refrigerant, the cascade heat exchanger 17 functions as an evaporator for the first refrigerant, and the cascade heat exchanger 17 functions to dissipate the heat of the second refrigerant. and the outdoor heat exchanger 18 functions as an evaporator for the second refrigerant.

Specifically, in this binary refrigeration cycle, the tenth on-off valve 50 and the twelfth on-off valve 52 are controlled to be closed, and the first expansion valve 15 and the second expansion valve 16 are controlled to be fully closed. , to prevent mixing of the first refrigerant and the second refrigerant. 12, the connection state of the second switching mechanism 22 is switched to the connection state indicated by the broken line in FIG. 12, and the pump 92, the first compressor 11, the 2 Compressor 21 and outdoor fan 9 are driven. Furthermore, the valve opening degree of the fifth expansion valve 35 is controlled so that the degree of superheat of the second refrigerant sucked into the first compressor 11 satisfies a predetermined condition, and the valve opening degree of the fourth expansion valve 34 is controlled for the second compression. Control is performed so that the degree of superheat of the first refrigerant sucked by the machine 21 satisfies a predetermined condition.

As a result, the second refrigerant discharged from the first compressor 11 is sent to the cascade heat exchanger 17, and when flowing through the first cascade flow path 17a, the first refrigerant flowing through the second cascade flow path 17b and the heat Dissipate heat by exchanging. The second refrigerant that has released heat in the cascade heat exchanger 17 passes through the third expansion valve 33, the first receiver 19a, and the branch point F, and is decompressed in the fifth expansion valve . The second refrigerant decompressed by the fifth expansion valve 35 is sent to the outdoor heat exchanger 18 via the branch point B. The second refrigerant evaporates by exchanging heat with the outdoor air supplied by the outdoor fan 9 in the outdoor heat exchanger 18, and passes through the branch point N, the eleventh on-off valve 51, and the first switching mechanism 12 to the first It is sucked into the compressor 11 . The first refrigerant discharged from the second compressor 21 is sent through the second switching mechanism 22 , the thirteenth on-off valve 53 and the branch point M to the first utilization flow path 13 a of the utilization heat exchanger 13 . The first refrigerant flowing through the first use flow path 13a of the heat utilization exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13b of the heat 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 first utilization flow path 13a of the utilization heat exchanger 13 passes through the branch point A, passes through the sixth expansion valve 36, and flows into the second receiver 19b. The first refrigerant that has flowed out of the second receiver 19b is decompressed in the fourth expansion valve 34 . The first refrigerant depressurized by the fourth expansion valve 34 evaporates by exchanging heat with the second refrigerant flowing through the first cascade flow path 17a when passing through the second cascade flow path 17b of the cascade heat exchanger 17. do. The first refrigerant evaporated in the second cascade flow path 17 b of the cascade heat exchanger 17 is drawn into the second compressor 21 .

(3-4) Heating/cooling shift operation The refrigerating cycle device 1b performs heating/cooling in the order of (a4) to (c4) below in order to shift from the cycle state in which the heating operation is performed to the cycle state in which the cooling operation is performed. A transition operation is performed.

(a4) First, the fifth expansion valve 35 is controlled to a fully closed state from the state in which the heating operation was performed, and the first compressor 11 is operated. Here, the second compressor 21 and the like are operated so as to maintain the refrigeration cycle on the user side during the heating operation using the first refrigerant. As a result, the second refrigerant discharged from the second compressor 21 is supplied to the first cascade flow path 17a of the cascade heat exchanger 17 while the second refrigerant of the outdoor heat exchanger 18 is drawn into the second compressor 21. An operation is performed to radiate heat, flow into the first receiver 19a, and collect the second refrigerant in the first receiver 19a. This operation is continued for a predetermined time, for example, until a predetermined sufficient amount of the second refrigerant is collected in the first receiver 19a.

(b4) Next, the eleventh on-off valve 51 is closed and the first compressor 11 is stopped in a state where the recovery of the second refrigerant to the refrigerant container 19 has progressed to a predetermined amount or more. After that, regarding the second switching mechanism 22 , the discharge side of the second compressor 21 is connected to the 12th on-off valve 52 , and the suction side of the second compressor 21 is connected to the 13th on-off valve 53 and the second opening of the cascade heat exchanger 17 . It switches to the state of being connected to the gas refrigerant side of the cascade flow path 17b. Then, the sixth expansion valve 36 and the fourth expansion valve 34 are controlled to be fully closed, and the second expansion valve 16 is controlled to be fully open. By operating the second compressor 21 in this state, the first refrigerant remaining in the first utilization flow path 13a of the utilization heat exchanger 13 and its surroundings is sucked into the second compressor 21, and the second compressor 21 It is condensed in the outdoor heat exchanger 18 by discharging from. The first refrigerant condensed in the outdoor heat exchanger 18 begins to accumulate in the second receiver 19b. Then, this operation is continued for a predetermined time.

(c4) Next, when the second receiver 19b has accumulated more than a predetermined amount of the first refrigerant, the thirteenth on-off valve 53 is controlled to be closed. Then, the first switching mechanism 12 is switched to a state in which the discharge side of the first compressor 11 is connected to the eleventh on-off valve 51, the suction side of the first compressor 11 is connected to the tenth on-off valve 50, and the tenth on-off valve 50 is connected. The on-off valve 50 is controlled to open, and the first expansion valve 15 is controlled to a predetermined opening degree.

With the above, the heating/cooling shift operation ends.

(3-5) Features of Third Embodiment In the refrigeration cycle device 1b of the third embodiment, in the refrigerant circuit 10, the first refrigerant having a sufficiently low global warming potential (GWP) and the ozone depletion potential (ODP) and a second refrigerant with a sufficiently low global warming potential (GWP). Therefore, deterioration of the global environment can be suppressed.

Further, in the refrigerating cycle device 1b of the third embodiment, the first refrigerant and the second refrigerant are obtained by using the first receiver 19a and the second receiver 19b used in the refrigerating cycle on the heat source side and the refrigerating cycle on the user side. are able to collect Therefore, it is not necessary to separately secure the refrigerant container 19 that is not used in the refrigeration cycle on the heat source side and the refrigeration cycle on the user side described in the second embodiment.

(4) Fourth Embodiment FIG. 9 shows a schematic configuration diagram of a refrigeration cycle apparatus 1c according to a fourth embodiment. FIG. 10 shows a functional block configuration diagram of a refrigeration cycle device 1c according to the second embodiment.

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

The heat load processed by the refrigeration cycle device 1c and the heat load circuit 90 are the same as in the first embodiment.

The refrigerant circuit 10 includes a first compressor 11, a second compressor 21, a first switching mechanism 12, a second switching mechanism 22, a utilization heat exchanger 13 shared with the heat load circuit 90, and a first Expansion valve 15, second expansion valve 16, third expansion valve 33, fourth expansion valve 34, fifth expansion valve 35, sixth expansion valve 36, cascade heat exchanger 17, outdoor heat exchange 18 , a first receiver 19 a , a second receiver 19 b , a 14th on-off valve 54 , a 15th on-off valve 55 , a 16th on-off valve 56 , and a 17th on-off valve 57 .

The specific configuration of the first compressor 11 itself is the same as that of the first embodiment. The discharge side of the first compressor 11 is connected to the switching valve 12c, switching valve 12d, and switching valve 12e of the first switching mechanism 12 . The suction side of the first compressor 11 is connected to different ports of the switching

valves

12 c , 12 d and 12 e of the first switching mechanism 12 .

The first switching mechanism 12 has a switching valve 12c, a switching valve 12d, and a switching valve 12e provided in parallel on the discharge side of the first compressor 11. In this embodiment, each of the switching valve 12c, the switching valve 12d, and the switching valve 12e is a three-way valve. The switching valve 12 c switches between a state in which the discharge side of the first compressor 11 is connected to the fourteenth on-off valve 54 and a state in which the suction side of the first compressor 11 is connected to the fourteenth on-off valve 54 . The switching valve 12d connects the discharge side of the first compressor 11 to the gas refrigerant side of the first cascade flow path 17a of the cascade heat exchanger 17, and connects the suction side of the first compressor 11 to the cascade heat exchanger 17. connected to the gas refrigerant side of the first cascade flow path 17a. The switching valve 12 e switches between a state in which the discharge side of the first compressor 11 is connected to the sixteenth on-off valve 56 and a state in which the suction side of the first compressor 11 is connected to the sixteenth on-off valve 56 .

The 14th on-off valve 54 is an electromagnetic valve that can be switched between an open state and a closed state. The fourteenth on-off valve 54 is provided in the middle of the flow path connecting the switching valve 12c of the first switching mechanism 12 and the branch point M. As shown in FIG.

At the branch point M, a flow path extending from the 14th on-off valve 54, a flow path extending from the 15th on-off valve 55, a flow path extending from the gas refrigerant side of the first utilization flow path 13a of the heat utilization heat exchanger 13, is connected.

The cascade heat exchanger 17 includes a first cascade flow path 17a through which one of the first refrigerant and the second refrigerant passes, and a second cascade flow path through which the other of the first refrigerant and the second refrigerant passes. 17b and a cascade heat exchanger for heat exchange between the first refrigerant and the second refrigerant. In the cascade heat exchanger 17 , the first cascade flow path 17 a and the second cascade flow path 17 b are independent of each other, and the first refrigerant and the second refrigerant do not mix inside the cascade heat exchanger 17 . A gas refrigerant side of the first cascade flow path 17 a is connected to a flow path extending from the switching valve 12 d of the first switching mechanism 12 . The liquid refrigerant side of the first cascade flow path 17 a is connected to a flow path extending from the third expansion valve 33 . A gas refrigerant side of the second cascade flow path 17 b is connected to a flow path extending from the switching valve 22 d of the second switching mechanism 22 . The liquid refrigerant side of the second cascade flow path 17 b is connected to a flow path extending from the fourth expansion valve 34 .

The specific configuration of the second compressor 21 itself is the same as that of the first embodiment. The discharge side of the second compressor 21 is connected to the switching valve 22c, the switching valve 22d, and the switching valve 22e of the second switching mechanism 22. As shown in FIG. The suction side of the second compressor 21 is connected to different ports of the switching

valves

22 c , 22 d and 22 e of the second switching mechanism 22 .

The second switching mechanism 22 has a switching valve 22c, a switching valve 22d, and a switching valve 22e provided in parallel with each other on the discharge side of the second compressor 21. In this embodiment, each of the switching valve 22c, the switching valve 22d, and the switching valve 22e is a three-way valve. The switching valve 22 c switches between a state in which the discharge side of the second compressor 21 is connected to the fifteenth on-off valve 55 and a state in which the suction side of the second compressor 21 is connected to the fifteenth on-off valve 55 . The switching valve 22d connects the discharge side of the second compressor 21 to the gas refrigerant side of the second cascade flow path 17b of the cascade heat exchanger 17, and connects the suction side of the second compressor 21 to the cascade heat exchanger 17. connected to the gas refrigerant side of the second cascade flow path 17b. The switching valve 22 e switches between a state in which the discharge side of the second compressor 21 is connected to the seventeenth on-off valve 57 and a state in which the suction side of the second compressor 21 is connected to the seventeenth on-off valve 57 .

At the branch point N, the flow path extending from the gas refrigerant side of the outdoor heat exchanger 18, the flow path extending from the 16th on-off valve 56, and the flow path extending from the 17th on-off valve 57 are connected.

The fifteenth on-off valve 55 is an electromagnetic valve that can be switched between an open state and a closed state. The fifteenth on-off valve 55 is provided in the middle of the flow path connecting the switching valve 22c of the second switching mechanism 22 and the branch point M. As shown in FIG.

The 16th on-off valve 56 is an electromagnetic valve that can be switched between an open state and a closed state. The sixteenth on-off valve 56 is provided in the middle of the flow path connecting the switching valve 12e of the first switching mechanism 12 and the branch point N. As shown in FIG.

The 17th on-off valve 57 is an electromagnetic valve that can be switched between an open state and a closed state. The seventeenth on-off valve 57 is provided in the middle of the flow path connecting the switching valve 22e of the second switching mechanism 22 and the branch point N. As shown in FIG.

In the refrigeration cycle apparatus 1c 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, a cooling/heating transitional operation, and a heating/cooling transitional operation are performed.

(4-1) Cooling Operation During the cooling operation, as shown in FIG. 15, the first refrigerant is used in the heat source side refrigerating cycle and the second refrigerant is used in the user side refrigerating cycle. In FIG. 11 , single arrows indicate channels through which the first coolant flows, and double arrows indicate channels through which the second coolant flows. In this binary refrigeration cycle, the utilization heat exchanger 13 functions as an evaporator for the second refrigerant, the cascade heat exchanger 17 functions as a radiator for the second refrigerant, and the cascade heat exchanger 17 functions as an evaporator for the first refrigerant. and the outdoor heat exchanger 18 functions as a condenser for the first refrigerant.

Specifically, in this binary refrigerating cycle, the fifteenth on-off valve 55 and the sixteenth on-off valve 56 are all controlled to be closed, and the fifth expansion valve 35 and the sixth expansion valve 36 are controlled to be fully closed. This prevents the first refrigerant and the second refrigerant from being mixed. The fourteenth on-off valve 54 and the seventeenth on-off valve 57 are controlled to be open. Then, the connected state of the first switching mechanism 12 is switched to the connected state indicated by the solid line in FIG. 15, the connected state of the second switching mechanism 22 is switched to the connected state indicated by the solid line in FIG. , the second compressor 21 and the outdoor fan 9 are driven. Further, the valve opening degree of the first expansion valve 15 is controlled so that the degree of superheat of the second refrigerant sucked into the first compressor 11 satisfies a predetermined condition, and the valve opening degree of the fourth expansion valve 34 is controlled for the second compression. Control is performed so that the degree of superheat of the first refrigerant sucked by the machine 21 satisfies a predetermined condition.

As a result, the first refrigerant discharged from the second compressor 21 is sent to the outdoor heat exchanger 18 via the switching valve 22e of the second switching mechanism 22, the seventeenth on-off valve 57, and the branch point N. The first refrigerant flowing through the outdoor heat exchanger 18 is condensed by exchanging heat with the outdoor air supplied by the outdoor fan 9 . The first refrigerant condensed in the outdoor heat exchanger 18 passes through the second expansion valve 16 controlled to be fully open, passes through the branch point G, and flows into the second receiver 19b. The refrigerant that has flowed out of the second receiver 19 b is decompressed in the fourth expansion valve 34 and sent to the second cascade flow path 17 b of the cascade heat exchanger 17 . When the first refrigerant flows through the second cascade flow path 17b of the cascade heat exchanger 17, the first refrigerant evaporates by exchanging heat with the second refrigerant flowing through the first cascade flow path 17a. The first refrigerant evaporated in the cascade heat exchanger 17 is sucked into the second compressor 21 via the switching valve 22d of the second switching mechanism 22 . The second refrigerant discharged from the first compressor 11 is sent to the first cascade flow path 17a of the cascade heat exchanger 17 via the switching valve 12d of the first switching mechanism 12 . When the second refrigerant flows through the first cascade flow path 17a of the cascade heat exchanger 17, the second refrigerant releases heat by exchanging heat with the first refrigerant flowing through the second cascade flow path 17b. The second refrigerant that has dissipated heat in the cascade heat exchanger 17 passes through the third expansion valve 33 that is controlled to be fully open and flows into the first receiver 19a. The second refrigerant that has flowed out of the first receiver 19 a is decompressed by the first expansion valve 15 , passes through the branch point A, and is sent to the first utilization flow path 13 a of the heat utilization exchanger 13 . The second refrigerant flowing through the first utilization flow path 13a of the utilization heat exchanger 13 exchanges heat with water flowing through the heat load flow path 13b of the utilization heat exchanger 13 of the heat load circuit 90, thereby evaporating. 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 second refrigerant evaporated in the first use flow path 13 a of the use heat exchanger 13 is sucked into the first compressor 11 via the fourteenth on-off valve 54 and the switching valve 12 c of the first switching mechanism 12 .

(4-2) Cooling/heating shift operation The refrigeration cycle device 1c performs the following steps (a5) to (b5) in order to shift from the cycle state in which the cooling operation is performed to the cycle state in which the heating operation is performed. A transition operation is performed.

(a5) First, the first compressor 11 is operated while the first expansion valve 15 is controlled to be fully closed from the state in which the cooling operation was performed. Here, the second compressor 21 and the like are operated so that the refrigeration cycle during the cooling operation using the first refrigerant is performed. As a result, the operation of recovering the second refrigerant into the first receiver 19a from below the first receiver 19a is performed. This operation is continued for a predetermined time, for example, until a predetermined sufficient amount of the second refrigerant is collected in the first receiver 19a.

(b5) Next, when the recovery of the second refrigerant to the first receiver 19a has progressed to a predetermined amount or more, the fourteenth on-off valve 54 is closed and the first compressor 11 is stopped. After that, the switching valve 22c of the second switching mechanism 22 is switched to the state in which the discharge side of the second compressor 21 is connected to the fifteenth on-off valve 55, and the switching valve 22e of the second switching mechanism 22 is switched to the second compressor 21. is connected to the seventeenth on-off valve 57, and the switching valve 22d of the second switching mechanism 22 connects the suction side of the second compressor 21 to the gas refrigerant in the second cascade flow path 17b of the cascade heat exchanger 17. remain connected to the side. Furthermore, the fifteenth on-off valve 55 is controlled to be open, the second expansion valve 16 and the fourth expansion valve 34 are controlled to be fully closed, and the sixth expansion valve 36 is controlled to be open. By operating the second compressor 21 in this state, the first refrigerant remaining in the outdoor heat exchanger 18 is heated by the heat of the air obtained from the outdoor fan 9 and driven out. Through the switching valve 22 e of the switching mechanism 22 , the second compressor 21 is caused to suck. Further, the first refrigerant remaining in the second cascade flow path 17b of the cascade heat exchanger 17 is also sucked into the second compressor 21 via the switching valve 22d of the second switching mechanism 22. The first refrigerant discharged from the second compressor 21 passes through the switching valve 22c of the second switching mechanism 22, the fifteenth on-off valve 55, and the branch point M to the first utilization flow path 13a of the utilization heat exchanger 13. Sent. Further, the first refrigerant is condensed while flowing through the first utilization channel 13a of the utilization heat exchanger 13, and flows through the branch point A and the sixth expansion valve 36 into the second receiver 19b. After continuing this operation for a predetermined time, the seventeenth on-off valve 57 is controlled to be closed, and the fourth expansion valve 34 is controlled to be opened.

With the above, the cooling/heating shift operation ends.

(4-3) Heating Operation During heating operation, as shown in FIG. 16, a dual refrigerating cycle is performed in which the second refrigerant is used in the heat source side refrigerating cycle and the first refrigerant is used in the user side refrigerating cycle. In FIG. 16 , single arrows indicate channels through which the first coolant flows, and double arrows indicate channels through which the second coolant flows. In this binary refrigerating cycle, the utilization heat exchanger 13 functions as a condenser for the first refrigerant, the cascade heat exchanger 17 functions as an evaporator for the first refrigerant, and the cascade heat exchanger 17 functions to dissipate the heat of the second refrigerant. and the outdoor heat exchanger 18 functions as an evaporator for the second refrigerant.

Specifically, in this binary refrigeration cycle, the 14th on-off valve 54 and the 17th on-off valve 57 are controlled to be closed, and the first expansion valve 15 and the second expansion valve 16 are controlled to be fully closed. , to prevent mixing of the first refrigerant and the second refrigerant. The connection state of the switching valve 12d and the switching valve 12c of the first switching mechanism 12 is set to the state indicated by the solid line in FIG. 16, and the connection state of the switching valve 12e of the first switching mechanism 12 is set to the state indicated by the broken line in FIG. The connection state of the switching valve 22d and the switching valve 22e of the second switching mechanism 22 is switched to the connection state indicated by the solid line in FIG. 16, and the connection state of the switching valve 22c of the second switching mechanism 22 is switched to the connection state indicated by the broken line in FIG. , the pump 92, the first compressor 11, the second compressor 21, and the outdoor fan 9 are driven. Furthermore, the valve opening degree of the fifth expansion valve 35 is controlled so that the degree of superheat of the second refrigerant sucked into the first compressor 11 satisfies a predetermined condition, and the valve opening degree of the fourth expansion valve 34 is controlled for the second compression. Control is performed so that the degree of superheat of the first refrigerant sucked by the machine 21 satisfies a predetermined condition.

As a result, the second refrigerant discharged from the first compressor 11 is sent to the cascade heat exchanger 17 via the switching valve 12d of the first switching mechanism 12, and when flowing through the first cascade flow path 17a, the second Heat is dissipated by exchanging heat with the first refrigerant flowing through the second cascade flow path 17b. The second refrigerant that has released heat in the cascade heat exchanger 17 passes through the third expansion valve 33, the first receiver 19a, and the branch point F, and is decompressed in the fifth expansion valve . The second refrigerant decompressed by the fifth expansion valve 35 is sent to the outdoor heat exchanger 18 via the branch point B. The second refrigerant evaporates by exchanging heat with the outdoor air supplied by the outdoor fan 9 in the outdoor heat exchanger 18, and passes through the branch point N, the 16th on-off valve 56, and the switching valve 12c of the first switching mechanism 12. , and is sucked into the first compressor 11 . The first refrigerant discharged from the second compressor 21 is sent to the first utilization passage 13a of the utilization heat exchanger 13 via the switching valve 22c of the second switching mechanism 22, the fifteenth on-off valve 55, and the branch point M. be done. The first refrigerant flowing through the first use flow path 13a of the heat utilization exchanger 13 is condensed by exchanging heat with water flowing through the heat load flow path 13b of the heat 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 first utilization flow path 13a of the utilization heat exchanger 13 passes through the branch point A, passes through the sixth expansion valve 36, and flows into the second receiver 19b. The first refrigerant that has flowed out of the second receiver 19b is decompressed in the fourth expansion valve 34 . The first refrigerant depressurized by the fourth expansion valve 34 evaporates by exchanging heat with the second refrigerant flowing through the first cascade flow path 17a when passing through the second cascade flow path 17b of the cascade heat exchanger 17. do. The first refrigerant evaporated in the second cascade flow path 17 b of the cascade heat exchanger 17 is sucked into the second compressor 21 via the switching valve 22 d of the second switching mechanism 22 .

(4-4) Heating/cooling shift operation The refrigerating cycle device 1c performs heating/cooling in the order of (a6) to (c6) below in order to shift from the cycle state in which the heating operation is performed to the cycle state in which the cooling operation is performed. A transition operation is performed.

(a6) First, the fifth expansion valve 35 is controlled to a fully closed state from the state in which the heating operation was being performed, and the first compressor 11 is operated. Here, the second compressor 21 and the like are operated so as to maintain the refrigeration cycle on the user side during the heating operation using the first refrigerant. As a result, the second refrigerant discharged from the second compressor 21 is supplied to the first cascade flow path 17a of the cascade heat exchanger 17 while the second refrigerant of the outdoor heat exchanger 18 is drawn into the second compressor 21. An operation is performed to radiate heat, flow into the first receiver 19a, and collect the second refrigerant in the first receiver 19a. This operation is continued for a predetermined time, for example, until a predetermined sufficient amount of the second refrigerant is collected in the first receiver 19a.

(b6) Next, when the collection of the second refrigerant into the refrigerant container 19 progresses to a predetermined amount or more, the sixteenth on-off valve 56 is closed to stop the first compressor 11 . After that, the switching valve 22c of the second switching mechanism 22 is switched to the state in which the suction side of the second compressor 21 is connected to the fifteenth on-off valve 55, and the switching valve 22e of the second switching mechanism 22 is switched to the second compressor 21. is connected to the 17th on-off valve 57, and for the switching valve 22d of the second switching mechanism 22, the suction side of the second compressor 21 is connected to the second cascade flow path 17b of the cascade heat exchanger 17. Stay connected to the refrigerant side. Then, the fourth expansion valve 34 and the sixth expansion valve 36 are controlled to be fully closed, the second expansion valve 16 is controlled to be fully open, and the seventeenth on-off valve 57 is controlled to be open. By operating the second compressor 21 in this state, the first refrigerant remaining in the first utilization flow path 13a of the utilization heat exchanger 13 and its surroundings is transferred to the branch point M, the fifteenth on-off valve 55, and the second switching mechanism. 22 to the second compressor 21 through the switching valve 22c. Then, the first refrigerant discharged from the second compressor 21 is sent to the outdoor heat exchanger 18 via the switching valve 22 e of the second switching mechanism 22 , the seventeenth on-off valve 57 and the branch point N. The first refrigerant that has exchanged heat with the air sent by the outdoor fan 9 in the outdoor heat exchanger 18 is condensed, passes through the branch point B, the second expansion valve 16, and the branch point G, and begins to accumulate in the second receiver 19b. . Then, this operation is continued for a predetermined time.

(c6) Next, when the second receiver 19b is filled with a predetermined amount or more of the first refrigerant, the fifteenth on-off valve 55 is controlled to be closed. Also, the fourteenth on-off valve 54 is controlled to open, and the first expansion valve 15 is controlled to a predetermined valve opening degree. Then, the switching valve 12c of the first switching mechanism 12 is switched to the state in which the suction side of the first compressor 11 and the fourteenth on-off valve 54 are connected, and the switching valve 12d of the first switching mechanism 12 is switched to the first switching mechanism. 12 switching valve 12e, the discharge side of the first compressor 11 and the 16th on-off valve 56 are connected, and the discharge side of the first compressor 11 and the first cascade flow path 17a of the cascade heat exchanger 17 are connected. Keep the gas refrigerant side connected.

With the above, the heating/cooling shift operation ends.

(4-5) Features of the Fourth Embodiment In the refrigeration cycle device 1c of the fourth embodiment, in the refrigerant circuit 10, the first refrigerant having a sufficiently low global warming potential (GWP) and the ozone depletion potential (ODP) and a second refrigerant with a sufficiently low global warming potential (GWP). Therefore, deterioration of the global environment can be suppressed.

Further, in the refrigerating cycle device 1c of the fourth embodiment, the first refrigerant and the second refrigerant are obtained by using the first receiver 19a and the second receiver 19b used in the refrigerating cycle on the heat source side and the refrigerating cycle on the user side. are able to collect Therefore, it is not necessary to separately secure the refrigerant container 19 that is not used in the refrigeration cycle on the heat source side and the refrigeration cycle on the user side described in the second embodiment.

(5) Other Embodiments (5-1) Other Embodiment A
In the above embodiment, each refrigerant is basically circulated while preventing the first refrigerant and the second refrigerant from being mixed with each other. However, as various operations are performed in the refrigerant circuit 10, the second refrigerant may flow where the first refrigerant flowed, and the first refrigerant may flow where the second refrigerant flowed. Therefore, it is conceivable that the first refrigerant and the second refrigerant are slightly mixed.

Here, different refrigerant species are used for the first refrigerant and the second refrigerant, but when these refrigerants are mixed, a non-azeotropic mixed refrigerant flows. In the heat exchanger functioning as an evaporator, this non-azeotropic mixed refrigerant produces a temperature gradient in which the refrigerant temperature on the upstream side when evaporation starts differs from the refrigerant temperature on the downstream side when evaporation ends. In addition, in the heat exchanger functioning as a condenser, this non-azeotropic mixed refrigerant produces a temperature gradient in which the refrigerant temperature on the upstream side when condensation starts differs from the refrigerant temperature on the downstream side when condensation ends.

Therefore, when the difference between the refrigerant evaporation temperature at a predetermined upstream position and the refrigerant evaporation temperature at a predetermined downstream position in the heat exchanger functioning as an evaporator is equal to or greater than a predetermined value, Alternatively, it may be evaluated that the first refrigerant and the second refrigerant are mixed. Further, in the heat exchanger functioning as a condenser, if the difference between the condensation temperature of the refrigerant at a predetermined upstream position and the condensation temperature of the refrigerant at a predetermined downstream position is equal to or greater than a predetermined value, Alternatively, it may be evaluated that the first refrigerant and the second refrigerant are mixed. Detection of each of these temperatures is not particularly limited, and can be detected by providing temperature sensors at predetermined upstream and downstream locations in the heat exchanger. In addition, when evaluating that the first refrigerant and the second refrigerant are mixed, the concentration of one of the refrigerants may be 90% by weight or less, or 95% by weight or less. or 98% by weight or less.

Further, when the controller 7 evaluates that the first refrigerant and the second refrigerant are mixed, the evaluation result may be displayed on a display (not shown) or the like.

(5-2) Other embodiment B
As described in other embodiment A above, the first refrigerant and the second refrigerant may intermix.

Therefore, in the refrigeration cycle device, when it is evaluated that the first refrigerant and the second refrigerant are mixed as described in the other embodiment A, when switching between the cooling operation and the heating operation is performed Alternatively, a separation process for separating the first refrigerant and the second refrigerant may be performed when switching between the cooling operation and the heating operation is performed a certain number of times.

The separation process is not particularly limited, and for example, an adsorbent that selectively adsorbs the first refrigerant or the second refrigerant may be provided in the refrigerant container 19, the first receiver 19a, and the second receiver 19b. Although the adsorbent is not particularly limited, for example, a metal-organic framework (MOF) may be used.

In addition, the refrigeration cycle device may be capable of distilling the first refrigerant, or may be capable of distilling the second refrigerant.

(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. .

Reference Signs List

1, 1a, 1b, 1c: refrigeration cycle device 12: first switching mechanism 12x: first switching mechanism 13: utilization heat exchanger 13a: first utilization passage 13b: heat load passage 14: third utilization expansion valve 15 : First expansion valve 16 : Second expansion valve 17 : Cascade heat exchanger 17a : First cascade channel 17b : Second cascade channel 18 : Outdoor heat exchanger 19 : Refrigerant container (second region)
19a: first receiver (second area)
19b: second receiver (first area)
21: Second compressor 33-36: Third to sixth expansion valves 41-49: First to ninth on-off valves 50-57: Tenth to seventeenth on-off valves 90: Heat load circuit 91: Heat load heat exchange Device 92: pump

JP 2015-197254 A

Claims

By performing a dual refrigeration cycle including a user side refrigeration cycle using a first refrigerant of 1 MPa or less at 30° C. and a heat source side refrigeration cycle using a second refrigerant of 1.5 MPa or more at 30° C. heating operation,
Cooling operation is performed by performing a unit refrigeration cycle using the first refrigerant,
A refrigeration cycle device (1).
An outdoor heat exchanger (18) that functions as an evaporator for the second refrigerant during the heating operation and functions as a radiator for the first refrigerant during the cooling operation,
The refrigeration cycle apparatus according to claim 1.
A first cascade flow path (17a) for flowing the first refrigerant during the heating operation and a second cascade flow path for flowing the second refrigerant during the heating operation are independent of the first cascade flow path (17a). a cascade heat exchanger (17) having a flow path (17b) for exchanging heat between the first refrigerant and the second refrigerant;
The refrigeration cycle apparatus according to claim 2.
A utilization heat exchanger (13) in which the first refrigerant releases heat during the heating operation,
During the heating operation, the first refrigerant evaporates when passing through the first cascade flow path (17a), and heat is released when the second refrigerant passes through the second cascade flow path (17b).
The refrigeration cycle device according to claim 3.
The first refrigerant evaporates in the utilization heat exchanger (13) during the cooling operation,
The refrigeration cycle apparatus according to claim 4.
The first refrigerant can be collected in a first region (19b) other than the outdoor heat exchanger, and the second region (19, 19a) other than the outdoor heat exchanger and other than the first region capable of collecting a second refrigerant,
The refrigeration cycle apparatus according to any one of claims 2 to 5.
By performing a dual refrigeration cycle including a user side refrigeration cycle using a first refrigerant of 1 MPa or less at 30° C. and a heat source side refrigeration cycle using a second refrigerant of 1.5 MPa or more at 30° C. heating operation,
Cooling operation is performed by performing a dual refrigeration cycle including a user-side refrigeration cycle using the second refrigerant and a heat source-side refrigeration cycle using the first refrigerant,
A refrigeration cycle device (1a, 1b, 1c).
Between the heating operation and the cooling operation, the refrigerant used in the refrigeration cycle on the heat source side and the refrigerant used in the refrigeration cycle on the user side are replaced.
The refrigeration cycle apparatus according to claim 7.
A refrigerant tank (19, 19a, 19b) that temporarily stores either the first refrigerant or the second refrigerant when the refrigerant is replaced,
The refrigeration cycle apparatus according to claim 8.
A first cascade flow path (17a) in which the first refrigerant evaporates during the heating operation is independent of the first cascade flow path (17a), and a second cascade flow path in which the second refrigerant releases heat during the heating operation. (17b), comprising a cascade heat exchanger (17) for exchanging heat between the first refrigerant and the second refrigerant;
The refrigeration cycle apparatus according to any one of claims 7 to 9.
a utilization heat exchanger (13) that functions as a radiator for the first refrigerant during the heating operation and functions as an evaporator for the second refrigerant during the cooling operation;
The refrigeration cycle apparatus according to any one of claims 7 to 10.
an outdoor heat exchanger (18) that functions as an evaporator for the second refrigerant during the heating operation and functions as a condenser for the first refrigerant during the cooling operation;
The refrigeration cycle apparatus according to any one of claims 7 to 11.
detecting a mixed state of the first refrigerant and the second refrigerant;
The refrigeration cycle apparatus according to any one of claims 1 to 12.
separating the first refrigerant and the second refrigerant;
The refrigeration cycle apparatus according to any one of claims 1 to 13.
The first refrigerant contains at least one of R1234yf and R1234ze,
The refrigeration cycle apparatus according to any one of claims 1 to 14.
The second refrigerant contains carbon dioxide,
The refrigeration cycle apparatus according to any one of claims 1 to 15.