Refrigerant Cycle System

Abstract

To solve a problem that in some cases, it is preferable to enable connection of a larger number of use side units to one heat source side unit.SOLUTION: A refrigerant cycle system 100 includes a first refrigerant circuit 1, a second refrigerant circuit 2, a third refrigerant circuit 3, a first cascade heat exchanger 21a, a second cascade heat exchanger 41a, a first flow regulating valve 22 and a second flow regulating valve 42. The first cascade heat exchanger 21a exchanges heat between a first refrigerant and a second refrigerant. The second cascade heat exchanger 41a exchanges heat between the first refrigerant and a third refrigerant. The first flow regulating valve 22 regulates the amount of the first refrigerant flowing into the first cascade heat exchanger 21a in the first refrigerant circuit 1. The second flow regulating valve 42 regulates the amount of the first refrigerant flowing into the second cascade heat exchanger 41a in the first refrigerant circuit 1. The first cascade heat exchanger 21a and the second cascade heat exchanger 41a are connected in parallel in the first refrigerant circuit 1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to refrigerant cycle systems. [Background technology]

[0002] Conventionally, a cascade refrigeration cycle has been known in which two vapor compression refrigeration cycles are connected via a cascade heat exchanger. In the cascade refrigeration cycle shown in Patent Document 1 (JP 2006-057869 A), an outdoor unit is a heat source unit, and user units such as an indoor unit, a refrigeration unit, and a freezing unit are connected to the outdoor unit. Summary of the Invention [Problem to be solved by the invention]

[0003] It may be preferable to be able to connect as many user-side units as possible to one heat source-side unit. [Means for solving the problem]

[0004] A refrigeration cycle system according to a first aspect includes a first refrigerant circuit, a second refrigerant circuit, a third refrigerant circuit, a first cascade heat exchanger, a second cascade heat exchanger, a first flow control valve, and a second flow control valve. The first refrigerant circuit is a vapor compression refrigeration cycle. The second refrigerant circuit is a vapor compression refrigeration cycle. The third refrigerant circuit is a vapor compression refrigeration cycle. The first cascade heat exchanger performs heat exchange between a first refrigerant and a second refrigerant. The first refrigerant is a refrigerant that flows through the first refrigerant circuit. The second refrigerant is a refrigerant that flows through the second refrigerant circuit. The second cascade heat exchanger performs heat exchange between the first refrigerant and a third refrigerant. The third refrigerant is a refrigerant that flows through the third refrigerant circuit. The first flow control valve adjusts the amount of the first refrigerant that enters the first cascade heat exchanger in the first refrigerant circuit. The second flow control valve adjusts the amount of the first refrigerant entering the second cascade heat exchanger in the first refrigerant circuit. The first cascade heat exchanger and the second cascade heat exchanger are connected in parallel in the first refrigerant circuit.

[0005] This makes it possible to connect more user-side units to one heat source-side unit.

[0006] A refrigeration cycle system according to a second aspect is the system according to the first aspect, further comprising a control unit. The control unit adjusts the apertures of the first flow control valve and the second flow control valve. When the first cascade heat exchanger of the first refrigerant circuit functions as an evaporator, the control unit adjusts the aperture of the first flow control valve so that the first refrigerant exiting the first cascade heat exchanger is superheated. When the second cascade heat exchanger of the first refrigerant circuit functions as an evaporator, the control unit adjusts the aperture of the second flow control valve so that the first refrigerant exiting the second cascade heat exchanger is superheated.

[0007] This makes it possible to control the degree of superheat of the first refrigerant.

[0008] A refrigeration cycle system according to a third aspect is the system according to the first or second aspect, further comprising a first internal heat exchanger, which exchanges heat in the first refrigerant circuit between the first refrigerant before it enters the first cascade heat exchanger and the first refrigerant after it leaves the first cascade heat exchanger.

[0009] The first internal heat exchanger controls the degree of superheat of the first refrigerant, thereby preventing a decrease in the heat exchange capacity of the first cascade heat exchanger.

[0010] A refrigeration cycle system according to a fourth aspect is the system according to the third aspect, wherein the first refrigerant circuit further includes a first bypass circuit. In the first refrigerant circuit, when the first cascade heat exchanger functions as a condenser, the first refrigerant that has left the first cascade heat exchanger bypasses the first internal heat exchanger via the first bypass circuit. The first refrigerant that has bypassed the first internal heat exchanger is drawn into a compressor included in the first refrigerant circuit.

[0011] By providing the first bypass circuit, when the first refrigerant circuit is in heating operation, the first refrigerant can bypass the first internal heat exchanger.

[0012] A refrigeration cycle system according to a fifth aspect is the system according to the third or fourth aspect, wherein the first cascade heat exchanger has a greater heat exchange capacity than the first internal heat exchanger.

[0013] The superheat state of the first refrigerant is controlled in the first internal heat exchanger, which makes it possible to control the superheat state of the first refrigerant without impairing the high heat exchange capacity of the first main heat exchange section.

[0014] A refrigeration cycle system according to a sixth aspect is the system according to any one of the first to fifth aspects, further comprising a second internal heat exchanger, which exchanges heat in the second refrigerant circuit between the first refrigerant before it enters the second cascade heat exchanger and the first refrigerant after it leaves the second cascade heat exchanger.

[0015] A seventh aspect of the present invention relates to a refrigeration cycle system, wherein the first refrigerant circuit further includes a second bypass circuit. When the second cascade heat exchanger functions as a condenser in the first refrigerant circuit, the first refrigerant that has flowed out of the second cascade heat exchanger bypasses the second internal heat exchanger via the second bypass circuit. The first refrigerant that has bypassed the second internal heat exchanger is drawn into a compressor included in the first refrigerant circuit.

[0016] By providing the second bypass circuit, when the first refrigerant circuit is in heating operation, the first refrigerant can bypass the second internal heat exchanger.

[0017] The refrigeration cycle system of an eighth aspect is the system of the sixth or seventh aspect, wherein the second cascade heat exchanger has a greater heat exchange capacity than the second internal heat exchanger.

[0018] The superheat state of the first refrigerant is controlled in the second internal heat exchanger, which makes it possible to control the superheat state of the first refrigerant without impairing the high heat exchange capacity of the first main heat exchange section.

[0019] A refrigeration cycle system according to a ninth aspect is the system according to any one of the first to eighth aspects, wherein the first and second refrigerants are any one of HFC refrigerants, HFO refrigerants, and natural refrigerants, or a mixed refrigerant containing any two or more of HFC refrigerants, HFO refrigerants, natural refrigerants, and CF3I.

[0020] A refrigeration cycle system according to a tenth aspect is the system according to any one of the first aspect to the ninth aspect, wherein the first refrigerant and the second refrigerant are R32.

[0021] This makes it possible to reuse an existing refrigerant cycle system.

[0022] A refrigeration cycle system according to an eleventh aspect is the system according to any one of the first to ninth aspects, wherein the first refrigerant is R32 and the second refrigerant is carbon dioxide. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a diagram showing a refrigerant circuit of the air conditioning apparatus. [Figure 2] FIG. 2 is a diagram illustrating an outline of a control unit. DETAILED DESCRIPTION OF THE INVENTION

[0024] (1) Overall structure As shown in FIG. 1, an air conditioning apparatus 100 as one embodiment of a refrigerant cycle device is an apparatus that cools and heats rooms in a building or other structure using a first refrigerant circuit 1, a second refrigerant circuit 2, and a third refrigerant circuit 3, which are vapor compression refrigeration cycles.

[0025] The air conditioning apparatus 100 mainly includes a heat source side unit 10 belonging to a first refrigerant circuit 1, a plurality of user side units 30A, 30B (two in this embodiment) belonging to a second refrigerant circuit 2, a plurality of user side units 50A, 50B (two in this embodiment) belonging to a third refrigerant circuit 3, a first cascade unit 20 arranged between the heat source side unit 10 and the user side units 30A, 30B, a second cascade unit 40 arranged between the heat source side unit 10 and the user side units 50A, 50B, refrigerant connection pipes 4a, 4b, 5a, 5b, 6a, 6b, and a control unit 60.

[0026] The first cascade unit 20 and the second cascade unit 40 are connected in parallel to each other in the first refrigerant circuit 1. The plurality of utilization side units 30A, 30B are connected in parallel to each other in the second refrigerant circuit 2. The plurality of utilization side units 50A, 50B are connected in parallel to each other in the third refrigerant circuit 3.

[0027] The control unit 60 is connected to the control units of each unit via a transmission line, etc. The control unit 60 controls each component device included in the air conditioner 100 and controls the air conditioner 100 as a whole.

[0028] The first refrigerant circuit 1, the second refrigerant circuit 2, and the third refrigerant circuit 3 are filled with R32 as the first refrigerant, the second refrigerant, and the third refrigerant, respectively.

[0029] (2) Detailed configuration of each unit (2-1) User unit The user units 30A, 30B, 50A, and 50B are installed indoors in a building or the like.

[0030] A plurality of user side units 30A, 30B constituting a part of the second refrigerant circuit 2 are connected to the first cascade unit 20 via a liquid refrigerant connection pipe 5a and a gas refrigerant connection pipe 5b as refrigerant connection pipes.

[0031] Furthermore, the plurality of user side units 50A, 50B that form part of the third refrigerant circuit 3 are connected to the second cascade unit 40 via a liquid refrigerant communication pipe 6a and a gas refrigerant communication pipe 6b that serve as refrigerant communication pipes.

[0032] Next, the configuration of the user side unit 30A will be described. Note that the user side unit 30A and the user side units 30B, 50A, and 50B have the same configuration, so only the configuration of the user side unit 30A will be described here, and descriptions of the configurations of the user side units 30B, 50A, and 50B will be omitted.

[0033] The utilization side unit 30A mainly includes a utilization side heat exchanger 31a and a flow rate adjustment valve 32a. Each component of the utilization side unit 30A is controlled by the control unit 60 via the utilization side control unit 64.

[0034] The user-side heat exchanger 31a is a heat exchanger that functions as an evaporator for the second refrigerant to cool the indoor air or as a radiator for the second refrigerant to heat the indoor air. Here, the user-side unit 30A has a user-side fan (not shown). The user-side fan supplies indoor air to the user-side heat exchanger 31a as a cooling or heating source for the second refrigerant flowing through the user-side heat exchanger 31a.

[0035] The flow rate control valve 32a is an electric expansion valve that can adjust the flow rate of the second refrigerant flowing through the user-side heat exchanger 31a while reducing the pressure of the second refrigerant. The opening degree of the flow rate control valve 32a is adjusted by the control unit 60 via the user-side control unit 64.

[0036] The user unit 30A is provided with various sensors (not shown). Values ​​detected by the sensors are sent to the control unit 60 via the user control unit 64.

[0037] (2-2) Heat source unit The heat source side unit 10, which constitutes part of the first refrigerant circuit 1, is installed outdoors, for example, on the roof or ground, of a building or the like. The heat source side unit 10 is connected to the first cascade unit 20 or the second cascade unit 40 via a liquid refrigerant communication pipe 4a and a gas refrigerant communication pipe 4b.

[0038] The heat source side unit 10 mainly has a compressor 11 and a heat source side heat exchanger 12. The heat source side unit 10 also has a switching mechanism 13 as a cooling / heating switching mechanism that switches between a cooling operation state in which the heat source side heat exchanger 12 functions as a refrigerant radiator and a heating operation state in which the heat source side heat exchanger 12 functions as a refrigerant evaporator. Each component of the heat source side unit 10 is controlled by a control unit 60 via a heat source side control unit 61.

[0039] The compressor 11 is a device for compressing the first refrigerant, and is, for example, a compressor of a sealed structure in which a volumetric compression element such as a rotary type or scroll type is rotationally driven by a compressor motor.

[0040] The heat source side heat exchanger 12 is a heat exchanger that functions as a radiator of the first refrigerant or as an evaporator of the first refrigerant. Here, the heat source side unit 10 has a heat source side fan (not shown). The heat source side fan draws outdoor air into the heat source side unit 10, exchanges heat with the first refrigerant in the heat source side heat exchanger 12, and then discharges the air to the outside.

[0041] The first refrigerant circuit 1 is provided with an expansion valve 14 near the liquid end of the heat source-side heat exchanger 12. The expansion valve 14 is an electrically operated expansion valve that reduces the pressure of the first refrigerant in heating operation. The opening degree of the expansion valve 14 is adjusted by the control unit 60 via the heat source-side control unit 61.

[0042] Various sensors (not shown) are provided in the heat source side unit 10. Values ​​detected by the sensors are sent to the control unit 60 via the heat source side control unit 61.

[0043] (2-3) Cascade unit The first cascade unit 20 and the second cascade unit 40 are installed, for example, in the space above the ceiling of a room in a building or the like.

[0044] The first cascade unit 20 is interposed between the utilization side units 30A, 30B and the heat source side unit 10, and constitutes a part of the first refrigerant circuit 1 and a part of the second refrigerant circuit 2.

[0045] The second cascade unit 40 is interposed between the utilization side units 50A, 50B and the heat source side unit 10, and constitutes a part of the first refrigerant circuit 1 and a part of the third refrigerant circuit 3.

[0046] Next, we will explain the configuration of the first cascade unit 20. Since the first cascade unit 20 and the second cascade unit 40 have the same configuration, only the configuration of the first cascade unit 20 will be explained here, and the explanation of the configuration of the second cascade unit 40 will be omitted.

[0047] The first cascade unit 20 mainly includes a first cascade heat exchanger 21a, a first internal heat exchanger 21b, a first flow control valve 22, a first bypass circuit 25, a first bypass valve 23, a compressor 26, and an expansion valve 28. The first cascade unit 20 also includes a switching mechanism 27 as a cooling / heating switching mechanism. Each component of the first cascade unit 20 is controlled by the control unit 60 via a first cascade control unit 62.

[0048] When the first cascade heat exchanger 21a functions as a radiator for the first refrigerant in the first refrigerant circuit 1, it functions as an evaporator for the second refrigerant in the second refrigerant circuit 2. When the first cascade heat exchanger 21a functions as an evaporator for the first refrigerant in the first refrigerant circuit 1, it functions as a radiator for the second refrigerant in the second refrigerant circuit 2. The first cascade heat exchanger 21a is a heat exchanger that exchanges heat between the first refrigerant flowing in the first refrigerant circuit 1 and the second refrigerant flowing in the second refrigerant circuit 2.

[0049] The first internal heat exchanger 21b is used to superheat the first refrigerant that has passed through the first cascade heat exchanger 21a. The superheated state refers to a state in which the first refrigerant is superheated. The degree of superheat is not limited, and a certain degree of superheat is sufficient. In cooling operation, the first internal heat exchanger 21b exchanges heat between the first refrigerant before it enters the first cascade heat exchanger 21a and the first refrigerant after it has left the first cascade heat exchanger 21a. In heating operation, the first bypass valve 23, which will be described later, is fully closed. As a result, the first refrigerant after it has left the first cascade heat exchanger 21a flows out of the first cascade unit 20 via a first bypass circuit 25, which will be described later, and the first internal heat exchanger 21b does not exchange heat.

[0050] The first cascade heat exchanger 21a is a heat exchanger having a greater heat exchange capacity than the first internal heat exchanger 21b. For example, the first cascade heat exchanger 21a is a plate heat exchanger, and the first internal heat exchanger 21b is a double-pipe heat exchanger.

[0051] The heat exchange capacity of a heat exchanger can be calculated based on the overall heat transfer coefficient, etc. The heat exchange capacity of a plate heat exchanger used as the first cascade heat exchanger 21a is greater than the heat exchange capacity of a double-pipe heat exchanger generally used as the first internal heat exchanger 21b.

[0052] The method for calculating the heat exchange capacity of the heat exchanger is not particularly limited.

[0053] The first refrigerant circuit 1 is provided with a first flow control valve 22 near the liquid side end of the first cascade heat exchanger 21a. The first flow control valve 22 is an electric expansion valve that reduces the pressure of the first refrigerant in cooling operation. The control unit 60 adjusts the valve opening degree of the first flow control valve 22 via the first cascade control unit 62 so that the first refrigerant discharged from the first internal heat exchanger 21b is superheated.

[0054] The first bypass circuit 25 is, for example, a capillary. In the first refrigerant circuit 1 in the heating operation state, the first refrigerant that flows out of the first cascade heat exchanger 21a bypasses the first internal heat exchanger 21b via the first bypass circuit 25. The first refrigerant that bypasses the first internal heat exchanger 21b flows out of the first cascade unit 20.

[0055] Furthermore, in the first refrigerant circuit 1 in the heating operation state, a first bypass valve 23 is provided upstream of the first internal heat exchanger 21b. The first bypass valve 23 is fully closed in the heating operation state. As a result, the first refrigerant after leaving the first cascade heat exchanger 21a flows out of the first cascade unit 20 via the first bypass circuit 25, and the first internal heat exchanger 21b does not perform heat exchange. The first bypass valve 23 is an electric expansion valve, and the opening degree of the valve is adjusted by the control unit 60 via the first cascade control unit 62.

[0056] The compressor 26 is a device for compressing the second refrigerant, and is, for example, a compressor of a sealed structure in which a volumetric compression element such as a rotary type or scroll type is rotationally driven by a compressor motor.

[0057] The second refrigerant circuit 2 is provided with an expansion valve 28 near the liquid side end of the first cascade heat exchanger 21a. The expansion valve 28 is an electric expansion valve that reduces the pressure of the refrigerant during heating operation. The opening degree of the expansion valve 28 is adjusted by the control unit 60 via the first cascade control unit 62.

[0058] 1, the first cascade unit 20 is further provided with an inlet temperature sensor 24a and an outlet temperature sensor 24b. The inlet temperature sensor 24a detects the temperature of the first refrigerant at the liquid side end of the first cascade heat exchanger 21a (inlet temperature) in the first refrigerant circuit 1. The outlet temperature sensor 24b detects the temperature of the first refrigerant at the gas side end of the first internal heat exchanger 21b in the first refrigerant circuit 1 (outlet temperature). The values ​​detected by the inlet temperature sensor 24a and the outlet temperature sensor 24b are sent to the control unit 60 via the first cascade control unit 62.

[0059] Although not shown, the first cascade unit 20 is also provided with various sensors other than those described above.

[0060] (2-4) Control unit 2, the control unit 60 has a heat source-side control unit 61, a first cascade control unit 62, a second cascade control unit 63, and use-side control units 64, 65, 66, and 67. Each of the control units 60, 61, 62, 63, 64, 65, 66, and 67 includes a processor such as a CPU or GPU, a memory, etc. The processor is capable of reading a program stored in the memory and performing predetermined processing in accordance with this program.

[0061] The heat source side control unit 61 is disposed in the heat source side unit 10. The heat source side control unit 61 controls the entire heat source side unit 10 and the opening degree of the expansion valve 14. The first cascade control unit 62 is disposed in the first cascade unit 20. The first cascade control unit 62 controls the entire first cascade unit 20 and the opening degrees of the first flow rate control valve 22, the first bypass valve 23, and the expansion valve 28. The second cascade control unit 63 is disposed in the second cascade unit 40. The second cascade control unit 63 controls the entire second cascade unit 40 and the opening degrees of the second flow rate control valve 42, the second bypass valve 43, and the expansion valve 48. The utilization side control unit 64 is disposed in the utilization side unit 30A. The utilization side control unit 64 controls the entire utilization side unit 30A and the opening degree of the flow rate control valve 32a. The usage-side control unit 65 is disposed in the usage-side unit 30B. The usage-side control unit 65 controls the entire usage-side unit 30B and the opening degree of the flow rate adjustment valve 32b. The usage-side control unit 66 is disposed in the usage-side unit 50A. The usage-side control unit 66 controls the entire usage-side unit 50A and the opening degree of the flow rate adjustment valve 52a. The usage-side control unit 67 is disposed in the usage-side unit 50B. The usage-side control unit 67 controls the entire usage-side unit 50B and the opening degree of the flow rate adjustment valve 52b.

[0062] The control unit 60 and each of the control units 61, 62, 63, 64, 65, 66, and 67 include a control board on which electrical components such as a microcomputer and memory are mounted, and the control unit 60 controls the entire air conditioning apparatus 100 via each of the control units 61, 62, 63, 64, 65, 66, and 67. The control unit 60 is able to receive values ​​detected by each of the sensors provided in the air conditioning apparatus 100 via each of the control units 61, 62, 63, 64, 65, 66, and 67, and send control signals and the like to each of the component devices.

[0063] Specifically, for example, the control unit 60 receives the inlet temperature detected by the inlet temperature sensor 24a and the outlet temperature detected by the outlet temperature sensor 24b provided in the first cascade unit 20 via the first cascade control unit 62. The control unit 60 is pre-installed with an opening adjustment algorithm for adjusting the opening of the first flow control valve 22. Using this opening adjustment algorithm, the control unit 60 generates a control signal for adjusting the first refrigerant exiting the first internal heat exchanger 21b to an appropriate degree of superheat, based on the inlet temperature and the outlet temperature. The first flow control valve 22 adjusts the opening of the first flow control valve 22 based on this control signal, thereby enabling the first refrigerant exiting the first internal heat exchanger 21b to have an appropriate degree of superheat.

[0064] The opening of the second flow rate control valve 42 in the second cascade unit 40 is adjusted in the same manner as described above. The control unit 60 receives the inlet temperature detected by the inlet temperature sensor 44a and the outlet temperature detected by the outlet temperature sensor 44b of the second cascade unit 40 via the second cascade control unit 63. The control unit 60 uses an opening adjustment algorithm to send a control signal to the second flow rate control valve 42 to adjust the opening of the second flow rate control valve 42. The second flow rate control valve 42 adjusts its opening based on the control signal.

[0065] The method by which the control unit 60 adjusts the opening degree of the first flow rate adjustment valve 22 or the second flow rate adjustment valve 42 is not limited to this.

[0066] (3) Basic operation of air conditioning equipment Next, we will explain the basic operation of the air conditioner 100. The basic operation of the air conditioner 100 includes cooling operation and heating operation. The basic operation of the air conditioner 100 explained below is performed by a control unit 60 that controls the components of the air conditioner 100 (heat source side unit 10, usage side units 30A, 30B, 50A, 50B, first cascade unit 20, and second cascade unit 40).

[0067] (3-1) Cooling operation For example, when all of the user side units 30A, 30B, 50A, and 50B are operating in cooling mode (all of the user side heat exchangers 31a, 31b, 51a, and 51b function as refrigerant evaporators, and the heat source side heat exchanger 12 functions as a refrigerant radiator), the switching mechanisms 13, 27, and 47 are switched to the cooling operation state (the state shown by the solid line in Figure 1).

[0068] (3-1-1) 1st refrigerant circuit During cooling operation, in the first refrigerant circuit 1, the high-pressure first refrigerant discharged from the compressor 11 is sent to the heat-source-side heat exchanger 12 through the switching mechanism 13. The first refrigerant sent to the heat-source-side heat exchanger 12 is cooled and condensed in the heat-source-side heat exchanger 12, which functions as a radiator for the first refrigerant, by exchanging heat with outdoor air supplied by the heat-source-side fan. This first refrigerant flows out of the heat-source-side unit 10 through the expansion valve 14.

[0069] The first refrigerant flowing out from the heat source side unit 10 is sent to the first cascade unit 20 and the second cascade unit 40.

[0070] The first refrigerant that flows into the first cascade unit 20 enters the first internal heat exchanger 21b. The first refrigerant that entered the first internal heat exchanger 21b exchanges heat with the first refrigerant that exited the first cascade heat exchanger 21a. The first refrigerant exits the first internal heat exchanger 21b and passes through the first bypass valve 23. The first refrigerant then enters the first flow control valve 22, which is adjusted to an appropriate opening by the control unit 60, and is depressurized. The depressurized first refrigerant enters the first cascade heat exchanger 21a. In the first cascade heat exchanger 21a, which functions as an evaporator for the first refrigerant, the first refrigerant is heated through heat exchange with the second refrigerant flowing through the second refrigerant circuit 2, and evaporates. The first refrigerant that exits the first internal heat exchanger 21b enters the first internal heat exchanger 21b and exchanges heat with the first refrigerant before entering the first cascade heat exchanger 21a. Heat exchange is performed here, and the first refrigerant that leaves first internal heat exchanger 21b has been given an appropriate degree of superheat. This first refrigerant flows out of first cascade unit 20, and is then combined with the first refrigerant that has flowed out of second cascade unit 40 before being drawn into compressor 11.

[0071] The first refrigerant that flows into the second cascade unit 40 enters the second internal heat exchanger 41b. The first refrigerant that enters the second internal heat exchanger 41b exchanges heat with the first refrigerant that exits the second cascade heat exchanger 41a. The first refrigerant exits the second internal heat exchanger 41b and passes through the second bypass valve 43. The first refrigerant then enters the second flow control valve 42, which is adjusted to an appropriate opening by the control unit 60, and is reduced in pressure. The reduced-pressure first refrigerant enters the second heat exchanger 41. The first refrigerant that enters the second heat exchanger 41a evaporates by being heated through heat exchange with the third refrigerant flowing through the third refrigerant circuit 3 in the second cascade heat exchanger 41a, which functions as an evaporator for the first refrigerant. The first refrigerant that exits the second internal heat exchanger 41b enters the second internal heat exchanger 41b and exchanges heat with the first refrigerant before entering the second cascade heat exchanger 41a. Heat exchange is performed here, and the first refrigerant that flows out of the second internal heat exchanger 41b has been given an appropriate degree of superheat. This first refrigerant flows out of the second cascade unit 40, and is then combined with the first refrigerant that flows out of the first cascade unit 20, before being drawn into the compressor 11.

[0072] (3-1-2)Second refrigerant circuit In the second refrigerant circuit 2, the high-pressure second refrigerant discharged from the compressor 26 is sent to the first cascade heat exchanger 21a via the switching mechanism 27. In the first cascade heat exchanger 21a, which functions as a radiator for the second refrigerant, the second refrigerant is cooled and condensed through heat exchange with the first refrigerant flowing through the first refrigerant circuit 1. This second refrigerant flows out of the first cascade unit 20 via the expansion valve 28. The second refrigerant flowing out of the first cascade unit 20 is sent to each of the user-side units 30A, 30B.

[0073] The second refrigerant sent to the user-side unit 30A is reduced in pressure to an appropriate level by the flow rate control valve 32a, and then evaporates in the user-side heat exchanger 31a, which functions as an evaporator for the second refrigerant, by exchanging heat with outdoor air supplied by the user-side fan. This second refrigerant flows out of the user-side unit 30A, and is then combined with the second refrigerant flowing out of the user-side unit 30B before being drawn into the compressor 26.

[0074] The second refrigerant sent to the user-side unit 30B is reduced in pressure to an appropriate level by the flow rate adjustment valve 32b, and then evaporates in the user-side heat exchanger 31b, which functions as an evaporator for the second refrigerant, by exchanging heat with outdoor air supplied by the user-side fan. This second refrigerant flows out of the user-side unit 30B, and is then combined with the second refrigerant flowing out of the user-side unit 30A before being drawn into the compressor 26.

[0075] On the other hand, the indoor air cooled in the utilization side heat exchangers 31a and 31b is sent to the room, thereby cooling the room.

[0076] (3-1-3) Third refrigerant circuit In the third refrigerant circuit 3, the high-pressure third refrigerant discharged from the compressor 44 is sent to the second cascade heat exchanger 41a via the switching mechanism 47. The third refrigerant sent to the second cascade heat exchanger 41a is cooled and condensed by heat exchange with the first refrigerant flowing through the first refrigerant circuit 1 in the second cascade heat exchanger 41a, which functions as a radiator for the third refrigerant. This third refrigerant flows out of the second cascade unit 40 via the expansion valve 46. The third refrigerant flowing out of the second cascade unit 40 is sent to each of the user-side units 50A, 50B.

[0077] The third refrigerant sent to the user-side unit 50A is reduced in pressure to an appropriate level by the flow rate adjustment valve 52a, and then evaporates in the user-side heat exchanger 51a, which functions as an evaporator for the third refrigerant, by exchanging heat with outdoor air supplied by the user-side fan. This third refrigerant flows out of the user-side unit 50A, and is then combined with the third refrigerant flowing out of the user-side unit 50B before being drawn into the compressor 44.

[0078] The third refrigerant sent to the user-side unit 50B is reduced in pressure to an appropriate level by the flow rate adjustment valve 52b, and then evaporates in the user-side heat exchanger 51b, which functions as an evaporator for the third refrigerant, by exchanging heat with outdoor air supplied by the user-side fan. This third refrigerant flows out of the user-side unit 50A, and is then combined with the third refrigerant flowing out of the user-side unit 50B before being drawn into the compressor 44.

[0079] On the other hand, the indoor air cooled in the utilization side heat exchangers 51a and 51b is sent to the room, thereby cooling the room.

[0080] (3-2) Heating operation For example, when all of the user side units 30A, 30B, 50A, and 50B are operating in heating mode (all of the user side heat exchangers 31a, 31b, 51a, and 51b function as refrigerant radiators and the heat source side heat exchanger 12 functions as a refrigerant evaporator), the switching mechanisms 13, 27, and 47 are switched to the heating mode (the mode indicated by the dashed lines in FIG. 1).

[0081] (3-2-1) 1st refrigerant circuit During heating operation, in the first refrigerant circuit 1, the high-pressure first refrigerant discharged from the compressor 11 flows out of the heat source side unit 10 through the switching mechanism 13.

[0082] The first refrigerant flowing out from the heat source side unit 10 is sent to the first cascade unit 20 and the second cascade unit 40.

[0083] The first refrigerant sent to the first cascade unit 20 passes through the first internal heat exchanger 21b and enters the first cascade heat exchanger 21a. At this time, the first refrigerant does not undergo heat exchange in the first internal heat exchanger 21b. The first refrigerant that entered the first cascade heat exchanger 21a is cooled and condensed by heat exchange with the second refrigerant flowing through the second refrigerant circuit 2. The condensed first refrigerant passes through the first flow control valve 22. Here, the opening degree of the first bypass valve 23 is adjusted by the control unit 60 and is in a fully closed state. The first refrigerant that passed through the first flow control valve 22 bypasses the first internal heat exchanger 21b via the first bypass circuit 25. The first refrigerant flows out of the first cascade unit 20. The first refrigerant that flows out of the first cascade unit 20 is combined with the first refrigerant that flows out of the second cascade unit 40 and sent to the heat source side unit 10.

[0084] The first refrigerant sent to the second cascade unit 40 passes through the second internal heat exchanger 41b and enters the second cascade heat exchanger 41a. At this time, the first refrigerant does not undergo heat exchange in the second internal heat exchanger 41b. The first refrigerant that entered the second cascade heat exchanger 41a is cooled and condensed by heat exchange with the third refrigerant flowing through the third refrigerant circuit 3. The condensed first refrigerant passes through the second flow control valve 42. Here, the opening degree of the second bypass valve 43 is adjusted by the control unit 60 and is in a fully closed state. The first refrigerant that passed through the second flow control valve 42 bypasses the second internal heat exchanger 41b via the second bypass circuit 45. The first refrigerant flows out of the second cascade unit 40. The first refrigerant that flows out of the second cascade unit 40 is combined with the first refrigerant that flows out of the first cascade unit 20 and sent to the heat source side unit 10.

[0085] The first refrigerant sent to the heat source side unit 10 is sent to the expansion valve 14. The first refrigerant sent to the expansion valve 14 is decompressed by the expansion valve 14, the opening of which is adjusted by the control unit 60, and then sent to the heat source side heat exchanger 12. The first refrigerant that enters the heat source side heat exchanger 12 is heated through heat exchange with outdoor air supplied by the heat source side fan, and evaporates. The evaporated first refrigerant is drawn into the compressor 11 through the switching mechanism 13.

[0086] (3-2-2)Second refrigerant circuit In the second refrigerant circuit 2, during heating operation, the high-pressure second refrigerant discharged from the compressor 26 flows out of the first cascade unit 20 through the switching mechanism 27.

[0087] The second refrigerant flowing out of the first cascade unit 20 is sent to each of the utilization side units 30A and 30B.

[0088] The second refrigerant sent to the user-side unit 30A exchanges heat with outdoor air supplied by the user-side fan in the user-side heat exchanger 31a, which functions as a refrigerant radiator, and condenses. The condensed second refrigerant passes through the flow control valve 32a and flows out of the user-side unit 30A. The second refrigerant flowing out of the user-side unit 30A is combined with the second refrigerant flowing out of the user-side unit 30B and sent to the first cascade unit 20.

[0089] The second refrigerant sent to the user-side unit 30B exchanges heat with outdoor air supplied by the user-side fan in the user-side heat exchanger 31b, which functions as a refrigerant radiator, and is condensed. The condensed second refrigerant passes through the flow rate adjustment valve 32b and flows out of the user-side unit 30B. The second refrigerant flowing out of the user-side unit 30B is combined with the second refrigerant flowing out of the user-side unit 30A and sent to the first cascade unit 20.

[0090] On the other hand, the indoor air heated in the utilization side heat exchangers 31a and 31b is sent to the room, thereby heating the room.

[0091] The second refrigerant that flows into the first cascade unit 20 flows into the expansion valve 28. The second refrigerant that flows into the expansion valve 28 is decompressed by the expansion valve 28 and then sent to the first cascade heat exchanger 21a. In the first cascade heat exchanger 21a, which functions as an evaporator for the second refrigerant, the second refrigerant is heated and evaporated through heat exchange with the first refrigerant flowing through the first refrigerant circuit 1. The evaporated second refrigerant is drawn into the compressor 26 through the switching mechanism 27.

[0092] (3-2-3) Third refrigerant circuit In the third refrigerant circuit 3, the high-pressure third refrigerant discharged from the compressor 44 flows out of the second cascade unit 40 through the switching mechanism 47.

[0093] The third refrigerant flowing out of the second cascade unit 40 is sent to each of the utilization side units 50A and 50B.

[0094] The third refrigerant sent to the user-side unit 50A exchanges heat with outdoor air supplied by the user-side fan in the user-side heat exchanger 51a, which functions as a refrigerant radiator, and condenses. The condensed third refrigerant passes through the flow control valve 52a and flows out of the user-side unit 50A. The third refrigerant flowing out of the user-side unit 50A is combined with the third refrigerant flowing out of the user-side unit 50B and sent to the second cascade unit 40.

[0095] The third refrigerant sent to the user-side unit 50B exchanges heat with the outdoor air supplied by the user-side fan in the user-side heat exchanger 51b, which functions as a refrigerant radiator, and is condensed. The condensed third refrigerant passes through the flow rate adjustment valve 52b and flows out of the user-side unit 50B. The third refrigerant flowing out of the user-side unit 50B is combined with the third refrigerant flowing out of the user-side unit 50A and sent to the second cascade unit 40.

[0096] On the other hand, the indoor air heated in the utilization side heat exchangers 51a and 51b is sent to the room, thereby heating the room.

[0097] The third refrigerant that flows into the second cascade unit 40 is sent to the expansion valve 46. The third refrigerant that flows into the expansion valve 46 is decompressed by the expansion valve 46 and then sent to the second cascade heat exchanger 41a. The third refrigerant that flows into the second cascade heat exchanger 41a is heated and evaporated in the second cascade heat exchanger 41a, which functions as an evaporator for the third refrigerant, by heat exchange with the first refrigerant flowing through the first refrigerant circuit 1. The evaporated third refrigerant is drawn into the compressor 44 through the switching mechanism 47.

[0098] (4) Variations (4-1) The first cascade heat exchanger 21a and the second cascade heat exchanger 41a of the air conditioner 100 are plate heat exchangers, and the first internal heat exchanger 21b and the second internal heat exchanger 41b are double-pipe heat exchangers. However, the heat exchange units are not limited to this.

[0099] For example, the first cascade heat exchanger 21a and the second cascade heat exchanger 41a may be heat exchangers formed by stacking multiple flat tubes, and the first internal heat exchanger 21b and the second internal heat exchanger 41b may be heat exchangers having a structure in which piping is in contact with each other.

[0100] The first cascade heat exchanger 21a may be any heat exchanger having a greater heat exchange capacity than the first internal heat exchanger 21b, and the second cascade heat exchanger 41a may be any heat exchanger having a greater heat exchange capacity than the second internal heat exchanger 41b.

[0101] The heat exchange capacity of a plate heat exchanger or a heat exchanger having a plurality of stacked flat tubes is generally greater than that of a heat exchanger having a double tube or a structure in which piping is in contact with each other.

[0102] (4-2) 1, the first cascade unit 20 of the air conditioning apparatus 100 is provided with an inlet temperature sensor 24a at the liquid side end of the first cascade heat exchanger 21a and an outlet temperature sensor 24b at the gas side end of the first internal heat exchanger 21b. However, the arrangement of the inlet temperature sensor and the outlet temperature sensor is not limited to this.

[0103] For example, the outlet temperature sensor 24b may be provided at the outlet of the first cascade heat exchanger 21a when the first refrigerant circuit 1 is in cooling operation.

[0104] (4-3) The first bypass circuit 25 and the second bypass circuit 45 of the air conditioning apparatus 100 are capillaries. However, the configuration of the first bypass circuit 25 and the second bypass circuit 45 is not limited to this. For example, the first bypass circuit 25 and the second bypass circuit 45 may be an electric expansion valve, an electric on-off valve, or a check valve.

[0105] The first bypass valve 23 and the second bypass valve 43 are electrically operated expansion valves. However, the configuration of the first bypass valve 23 and the second bypass valve 43 is not limited to this. For example, the first bypass valve 23 and the second bypass valve 43 may be electrically operated on-off valves or check valves.

[0106] (4-4) The first refrigerant circuit 1, the second refrigerant circuit 2, and the third refrigerant circuit 3 of the air conditioner 100 are filled with R32, a highly stable refrigerant, as the first refrigerant, the second refrigerant, and the third refrigerant, respectively. However, the refrigerant cycle system described in this disclosure may be filled with a refrigerant other than R32. For example, it is preferable that the first refrigerant is R32, and the second refrigerant and the third refrigerant are carbon dioxide.

[0107] The first, second, and third refrigerants charged into the refrigeration cycle system are preferably any one of HFC refrigerants, HFO refrigerants, and natural refrigerants. Alternatively, the first and second refrigerants are preferably mixed refrigerants containing two or more of HFC refrigerants, HFO refrigerants, natural refrigerants, and CF3I. Specific examples of HFC refrigerants include R32, R125, R134a, R143a, and R245fa. Examples of HFO refrigerants include R1234yf, R1234zd, R1123, and R1132(E). Examples of natural refrigerants include R744, R717, R290, R600a, and R1270.

[0108] (4-5) The refrigerant cycle system shown in this disclosure is described using the air conditioner 100 as a specific example of a refrigerant cycle system, but the form of the refrigerant cycle system is not limited to this. For example, the refrigerant cycle system may be a heat pump water heater or the like.

[0109] (5) Features (5-1) The air conditioner 100 as a refrigerant cycle system disclosed in the present disclosure includes a first refrigerant circuit 1, a second refrigerant circuit 2, a third refrigerant circuit 3, a first cascade heat exchanger 21a, a second cascade heat exchanger 41a, a first flow control valve 22, and a second flow control valve 42. The first refrigerant circuit 1 is a vapor compression refrigeration cycle. The second refrigerant circuit 2 is a vapor compression refrigeration cycle. The third refrigerant circuit 3 is a vapor compression refrigeration cycle. The first cascade heat exchanger 21a performs heat exchange between a first refrigerant and a second refrigerant. The first refrigerant is a refrigerant that flows through the first refrigerant circuit 1. The second refrigerant is a refrigerant that flows through the second refrigerant circuit 2. The second cascade heat exchanger 41a performs heat exchange between the first refrigerant and a third refrigerant. The third refrigerant is a refrigerant that flows through the third refrigerant circuit 3. The first flow control valve 22 adjusts the amount of first refrigerant entering the first cascade heat exchanger 21a in the first refrigerant circuit 1. The second flow control valve 42 adjusts the amount of first refrigerant entering the second cascade heat exchanger 41a in the first refrigerant circuit 1. The first cascade heat exchanger 21a and the second cascade heat exchanger 41a are connected in parallel in the first refrigerant circuit 1.

[0110] Conventionally, a cascade refrigeration cycle has been known in which vapor compression refrigeration cycles are connected via a cascade heat exchanger. A cascade refrigeration cycle is preferable in cases where air conditioners are installed in large commercial facilities or buildings, as it allows multiple user units to be connected to one heat source unit. This can reduce the space and cost required for installing the air conditioner.

[0111] The air conditioner 100 shown in this embodiment has a first refrigerant circuit 1, which is a vapor compression refrigeration cycle, and a second refrigerant circuit 2 having a first cascade heat exchanger 21a and a third refrigerant circuit 3 having a second cascade heat exchanger 41a connected in parallel. This makes it possible to connect more utilization units to one heat source unit.

[0112] (5-2) The air conditioning apparatus 100 further includes a control unit 60. The control unit 60 adjusts the apertures of the first flow control valve 22 and the second flow control valve 42. When the first cascade heat exchanger 21a of the first refrigerant circuit 1 functions as an evaporator, the control unit 60 adjusts the aperture of the first flow control valve 22 so that the first refrigerant exiting the first cascade heat exchanger 21a is superheated. When the second cascade heat exchanger 41a of the first refrigerant circuit 1 functions as an evaporator, the control unit 60 adjusts the aperture of the second flow control valve 42 so that the first refrigerant exiting the second cascade heat exchanger 42a is superheated.

[0113] The control unit 60 can adjust the opening degree of the first flow control valve 22 and the second flow control valve 42. This allows the control unit 60 to control the degree of superheat of the first refrigerant exiting the first cascade heat exchanger 21a or the second cascade heat exchanger 42a, enabling the air conditioning apparatus 100 to be driven efficiently.

[0114] (5-3) The air conditioning apparatus 100 further includes a first internal heat exchanger 21b. The first internal heat exchanger 21b performs heat exchange in the first refrigerant circuit 1 between the first refrigerant before it enters the first cascade heat exchanger 21a and the first refrigerant after it leaves the first cascade heat exchanger 21a.

[0115] The first refrigerant circuit 1 of the air conditioning apparatus 100 further includes a first bypass circuit 25. In the first refrigerant circuit 1, when the first cascade heat exchanger 21a functions as a condenser, the first refrigerant that leaves the first cascade heat exchanger 21a bypasses the first internal heat exchanger 21b via the first bypass circuit 25. The first refrigerant that has bypassed the first internal heat exchanger 21b is drawn into the compressor 11 included in the first refrigerant circuit 1.

[0116] The first cascade heat exchanger 21a of the air conditioner 100 has a greater heat exchange capacity than the first internal heat exchanger 21b.

[0117] By providing the first internal heat exchanger 21b, the air conditioning apparatus 100 can suppress a decrease in the heat exchange capacity of the first cascade heat exchanger 21a that occurs when controlling the degree of superheat of the first refrigerant. Furthermore, by providing the first bypass circuit 25, the air conditioning apparatus 100 can allow the first refrigerant to bypass the first internal heat exchanger 21b when the first refrigerant circuit 1 is in heating operation. Note that the first cascade heat exchanger 21a is preferably a high-performance heat exchanger with large heat exchange capacity. Furthermore, the first internal heat exchanger 21b is a heat exchanger that can impart superheat to the first refrigerant without impairing the heat exchange capacity of the first cascade heat exchanger 21a.

[0118] (5-4) The air conditioning apparatus 100 further includes a second internal heat exchanger 41b. The second internal heat exchanger 41b performs heat exchange in the second refrigerant circuit 2 between the first refrigerant before it enters the second cascade heat exchanger 41a and the first refrigerant after it leaves the second cascade heat exchanger 41a.

[0119] In the air conditioning apparatus 100, the first refrigerant circuit 1 further includes a second bypass circuit 45. In the first refrigerant circuit 1, when the second cascade heat exchanger 41a functions as a condenser, the first refrigerant that leaves the second cascade heat exchanger 41a bypasses the second internal heat exchanger 41b via the second bypass circuit 45. The first refrigerant that has bypassed the second internal heat exchanger 41b is drawn into the compressor 11 included in the first refrigerant circuit 1.

[0120] Furthermore, the second cascade heat exchanger 41a of the air conditioner 100 has a greater heat exchange capacity than the second internal heat exchanger 41b.

[0121] As a result, the third refrigerant circuit 3 can also achieve the same effects as the second refrigerant circuit 2.

[0122] (5-5) The first refrigerant circuit 1, the second refrigerant circuit 2, and the third refrigerant circuit 3 of the air conditioner 100 are filled with R32, a highly stable refrigerant, as the first refrigerant, the second refrigerant, and the third refrigerant, respectively. However, the refrigerant cycle system described in this disclosure may be filled with a refrigerant other than R32. For example, it is preferable that the first refrigerant is R32, and the second refrigerant and the third refrigerant are carbon dioxide.

[0123] The first, second, and third refrigerants charged into the refrigeration cycle system are preferably any one of HFC refrigerants, HFO refrigerants, and natural refrigerants, or the first and second refrigerants are preferably mixed refrigerants containing any two or more of HFC refrigerants, HFO refrigerants, natural refrigerants, and CF3I.

[0124] The refrigerant filled in the air conditioner 100 of this embodiment may be, for example, any of the refrigerants listed above.

[0125] (6) Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims. [Explanation of symbols]

[0126] 1 1st refrigerant circuit 2 Second refrigerant circuit 3 Third refrigerant circuit 11 Compressor 21a First cascade heat exchanger 21b 1st internal heat exchanger 22 First flow control valve 25 First bypass circuit 41a Second cascade heat exchanger 41b Second internal heat exchanger 42 Second flow control valve 45 Second bypass circuit 60 Control Unit 100 Refrigerant Cycle System [Prior art documents] [Patent documents]

[0127] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-057869

Claims

1. a first refrigerant circuit (1) which is a vapor compression refrigeration cycle including a compressor (11) provided in a heat source side unit (10); a second refrigerant circuit (2) which is a vapor compression refrigeration cycle including utilization side heat exchangers (31a, 31b) provided in the utilization side units (30A, 30B); a third refrigerant circuit (3) which is a vapor compression refrigeration cycle including utilization side heat exchangers (51a, 51b) provided in the utilization side units (50A, 50B); a first cascade heat exchanger (21a) for performing heat exchange between a first refrigerant that is a refrigerant flowing through the first refrigerant circuit (1) and a second refrigerant that is a refrigerant flowing through the second refrigerant circuit (2); a second cascade heat exchanger (41 a) for performing heat exchange between the first refrigerant and a third refrigerant that is a refrigerant flowing through the third refrigerant circuit (3); a first flow rate control valve (22) in the first refrigerant circuit (1) for adjusting the amount of the first refrigerant entering the first cascade heat exchanger (21 a); a second flow rate control valve (42) in the first refrigerant circuit (1) for controlling the amount of the first refrigerant entering the second cascade heat exchanger (41 a); Equipped with In the first refrigerant circuit (1), the first cascade heat exchanger (21a) and the second cascade heat exchanger (41a) are connected in parallel, In the first refrigerant circuit (1), a first internal heat exchanger (21b) for exchanging heat between the first refrigerant before it enters the first cascade heat exchanger (21a) and the first refrigerant after it leaves the first cascade heat exchanger (21a); a second internal heat exchanger (41b) for exchanging heat between the first refrigerant before it enters the second cascade heat exchanger (41a) and the first refrigerant after it leaves the second cascade heat exchanger (41a); a first bypass circuit (25); Furthermore, The first cascade heat exchanger (21a) has a larger heat exchange capacity than the first internal heat exchanger (21b), The second cascade heat exchanger (41a) has a larger heat exchange capacity than the second internal heat exchanger (41b), When the first cascade heat exchanger (21 a) serves as a condenser in the first refrigerant circuit (1), the first refrigerant that has left the first cascade heat exchanger (21 a) bypasses the first internal heat exchanger (21 b) via the first bypass circuit (25) and is drawn into the compressor (11) of the first refrigerant circuit (1). A refrigerant cycle system (100).

2. a control unit (60) that adjusts the opening degrees of the first flow rate adjustment valve (22) and the second flow rate adjustment valve (42); Furthermore, When the first cascade heat exchanger (21 a) of the first refrigerant circuit (1) functions as an evaporator, the control unit (60) adjusts the opening degree of the first flow rate control valve (22) so that the first refrigerant exiting the first cascade heat exchanger (21 a) is in a superheated state; When the second cascade heat exchanger (41 a) of the first refrigerant circuit (1) functions as an evaporator, the control unit (60) adjusts the opening degree of the second flow rate control valve (42) so that the first refrigerant flowing out of the second cascade heat exchanger (41 a) is in a superheated state. The refrigerant cycle system (100) of claim 1.

3. The first refrigerant circuit (1) further includes a second bypass circuit (45), When the second cascade heat exchanger (41 a) serves as a condenser in the first refrigerant circuit (1), the second refrigerant that has left the second cascade heat exchanger (41 a) bypasses the second internal heat exchanger (41 b) via the second bypass circuit (45) and is drawn into the compressor (11) of the first refrigerant circuit (1). The refrigerant cycle system (100) of claim 1 or 2.

4. the first refrigerant and the second refrigerant are any one of an HFC refrigerant, an HFO refrigerant, and a natural refrigerant, or a mixed refrigerant containing any two or more of an HFC refrigerant, an HFO refrigerant, a natural refrigerant, and CF3I; A refrigerant cycle system (100) according to any one of claims 1 to 3.

5. The first refrigerant and the second refrigerant are R32. A refrigerant cycle system (100) according to any one of claims 1 to 4.

6. The first refrigerant is R32, The second refrigerant is carbon dioxide. A refrigerant cycle system (100) according to any one of claims 1 to 4.

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