Refrigerant cycle system

Abstract

To solve a problem that when a flammable or toxic refrigerant is used, refrigerant filling amount allowable per indoor volume is restricted in some cases, but there is no description about the restriction of the refrigerant filling amount in Patent Document 1.SOLUTION: A refrigerant cycle system 100 includes a first refrigerant circuit 1 and a second refrigerant circuit 2. The first refrigerant circuit 1 includes a first heat exchanger 11, a first compressor 12 and a first cascade heat exchanger 21. The second refrigerant circuit 2 includes a first cascade heat exchanger 21, a second compressor 22 and second heat exchangers 31A, 31B. The first heat exchanger 11 and the first compressor 12 are accommodated in a first unit 10. The first cascade heat exchanger 21 and the second compressor 22 are accommodated in a second unit 20. The second heat exchangers 31A, 31B are accommodated in a third unit 30. The first unit 10, the second unit 20 and the third unit 30 are disposed to separate from each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This invention relates to a refrigerant cycle system. [Background technology]

[0002] As disclosed in Patent Document 1 (JP 2018-194260 A), there is a refrigeration apparatus such as an air conditioner in which a plurality of utilization-side heat exchangers are connected to one heat source-side heat exchanger. Summary of the Invention [Problem to be solved by the invention]

[0003] When using a flammable or toxic refrigerant, the allowable refrigerant charge amount per indoor volume may be limited, but Patent Document 1 is silent about any restrictions on the refrigerant charge amount. [Means for solving the problem]

[0004] A refrigeration cycle system according to a first aspect includes a first refrigerant circuit and a second refrigerant circuit. The first refrigerant circuit is a vapor compression refrigeration cycle. The second refrigerant circuit is a vapor compression refrigeration cycle. The first refrigerant circuit includes a first heat exchanger, a first compressor, and a first cascade heat exchanger. The second refrigerant circuit includes a first cascade heat exchanger, a second compressor, and a second heat exchanger. The first heat exchanger and the first compressor are housed in a first unit. The first cascade heat exchanger and the second compressor are housed in a second unit. The second heat exchanger is housed in a third unit. The first unit, the second unit, and the third unit are disposed apart from each other. The first cascade heat exchanger exchanges heat between a first refrigerant flowing through the first refrigerant circuit and a second refrigerant flowing through the second refrigerant circuit.

[0005] According to this configuration, it is possible to reduce the amount of refrigerant charged relative to the indoor volume, and to prevent the amount of refrigerant charged from exceeding a limit.

[0006] A refrigeration cycle system according to a second aspect is the system according to the first aspect, further comprising a second cascade heat exchanger, a third compressor, a third heat exchanger, a fourth unit, and a fifth unit. The third refrigerant circuit is configured by connecting the second cascade heat exchanger, the third compressor, and the third heat exchanger. The second cascade heat exchanger and the third compressor are housed in the fourth unit. The third heat exchanger is housed in the fifth unit. The first unit, the fourth unit, and the fifth unit are disposed apart from each other. The second cascade heat exchanger causes heat exchange between the first refrigerant and the third refrigerant flowing through the third refrigerant circuit.

[0007] This makes it possible to connect more utilization-side heat exchangers to one heat source-side heat exchanger.

[0008] A refrigeration cycle system according to a third aspect is the system according to the second aspect, further comprising a first refrigerant flow path switching unit between the first unit and the second unit for switching a flow path of the first refrigerant.

[0009] This allows freedom of flow of the first refrigerant, which can contribute to combined cooling and heating operation.

[0010] A refrigerant cycle system of a fourth aspect is the system of any one of the first aspect to the third aspect, further comprising a second refrigerant flow path switching unit between the second unit and the third unit for switching a flow path of the second refrigerant.

[0011] This allows freedom of flow of the second refrigerant, which contributes to combined cooling and heating operation.

[0012] A refrigeration cycle system according to a fifth aspect is the system according to any one of the first aspect to the fourth aspect, wherein the second refrigerant flowing through the second refrigerant circuit is flammable or toxic.

[0013] The configuration of the refrigerant cycle system disclosed in the present disclosure reduces the amount of refrigerant flowing through each refrigerant circuit, making it possible to ensure greater safety even when using a flammable or toxic refrigerant.

[0014] A refrigeration cycle system according to a sixth aspect is the system according to any one of the first to fifth aspects, wherein the first and second refrigerants are any one of HFC refrigerants, HFO refrigerants, and natural refrigerants, or the first and second refrigerants are mixed refrigerants containing any two or more of HFC refrigerants, HFO refrigerants, natural refrigerants, and CF3I.

[0015] A refrigeration cycle system according to a seventh aspect is the system according to any one of the first aspect to the sixth aspect, in which the first refrigerant is R32.

[0016] A refrigeration cycle system according to an eighth aspect is the system according to any one of the first aspect to the seventh aspect, in which the first refrigerant and the second refrigerant are R32.

[0017] This makes it possible to utilize an existing refrigerant cycle system.

[0018] A refrigeration cycle system according to a ninth aspect is the system according to any one of the first aspect to the eighth aspect, in which the second compressor housed in the second unit is of a horizontal type.

[0019] The horizontally-mounted second compressor is preferable for installation in a low-height space such as above the ceiling.

[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 second refrigerant circuit has an expansion mechanism, and the second refrigerant flowing into the expansion mechanism is in a gas-liquid two-phase state.

[0021] This makes it possible to reduce the amount of the second refrigerant flowing through the second refrigerant circuit.

[0022] A refrigeration cycle system according to an eleventh aspect is the system according to any one of the first to tenth aspects, wherein the first refrigerant circuit further includes a fourth heat exchanger and a sixth unit. The fourth heat exchanger is used as a utilization side heat exchanger. The sixth unit houses the fourth heat exchanger. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a diagram showing a refrigerant circuit of the air conditioning device. [Diagram 2] FIG. 2 is a diagram showing an outline of a control unit. [Diagram 3] FIG. 4 is a diagram showing a refrigerant circuit of a first unit. [Figure 4A] FIG. 4 is a diagram showing refrigerant circuits of a second unit and a first branching unit. [Figure 4B] FIG. 13 is a diagram showing refrigerant circuits of a fourth unit and a third branching unit. [Figure 5A] FIG. 4 is a diagram showing refrigerant circuits of a third unit and a second branching unit. [Figure 5B] FIG. 13 is a diagram showing refrigerant circuits of a fifth unit and a fourth branching unit. [Figure 6] FIG. 11 is a diagram showing a first refrigerant circuit in a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] (1) Air conditioning system configuration 1 is a diagram showing a refrigerant circuit of an air conditioner 100. The air conditioner 100, which is one embodiment of a refrigerant cycle system, performs cooling and heating within a building such as a building by 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 device 100 mainly comprises a first unit 10, a second unit 20, multiple (here, two) third units 30A, 30B, a fourth unit 40, multiple (here, two) fifth units 50A, 50B, a first branch unit 60, multiple (here, two) second branch units 70A, 70B, a third branch unit 80, multiple (here, two) fourth branch units 90A, 90B, and a refrigerant connection pipe.

[0026] The first refrigerant circuit 1 is formed by connecting a first unit 10 which is a heat source unit, a second unit 20 which is a cascade unit, a first branch unit 60, a third unit 30 which is also a cascade unit, a third branch unit 80, and refrigerant connection pipes 1A, 1B, and 1C (see Figures 3, 4A, and 4B).

[0027] The second refrigerant circuit 2 is configured by connecting the second unit 20, the third units 30A and 30B which are user side units, the second branch units 70A and 70B, and the refrigerant connection pipes 2A, 2B, and 2C (see FIGS. 4A and 5A). The second refrigerant circuit 2 of the air conditioner 100 is configured to enable a mixed cooling and heating operation in which heating and cooling are selected for each user side unit.

[0028] The third refrigerant circuit 3 is configured by connecting the fourth unit 40, the fifth units 50A and 50B which are user side units, the fourth branch units 90A and 90B, and the refrigerant connection pipes 3A, 3B, and 3C (see Figs. 4B and 5B). The third refrigerant circuit 3 of the air conditioner 100 is configured to enable a mixed cooling and heating operation in which heating and cooling are selected for each user side unit.

[0029] 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.

[0030] The air conditioning device 100 also has a control unit 101 shown in Fig. 2. The control unit 101 is arranged in, for example, the first unit 10, but is not limited to this. The control unit 101 includes a first control unit 19 arranged in the first unit 10, a second control unit 29 arranged in the second unit 20, a third control unit 39 arranged in the third unit 30, a fourth control unit 49 arranged in the fourth unit 40, a fifth control unit 59 arranged in the fifth unit 50, a first branch control unit 69 arranged in the first branch unit 60, a second branch control unit 79 arranged in the second branch unit 70, a third branch control unit 89 arranged in the third branch unit 80, and a fourth branch control unit 99 arranged in the fourth branch unit 90.

[0031] Each of the control units 101, 19, 29, 39, 49, 59, 69, 79, 89, 99 includes a control board on which electrical components such as a microcomputer and a memory are mounted, and the control unit 101 controls the entire air conditioning device 100 via each of the control units 19, 29, 39, 49, 59, 69, 79, 89, 99 arranged in each of the units 10, 20, 30, 40, 50, 60, 70, 80, 90. For example, the control unit 101 receives values ​​detected by sensors provided in each of the units 10, 20, 30, 40, 50, 60, 70, 80, 90 via each of the control units 19, 29, 39, 49, 59, 69, 79, 89, 99 arranged in each of the units 10, 20, 30, 40, 50, 60, 70, 80, 90. Furthermore, for example, the control unit 101 can send control signals and the like to the components included in each of the units 10, 20, 30, 40, 50, 60, 70, 80, and 90.

[0032] (2) Detailed configuration of each unit (2-1) Unit 1 Fig. 3 shows the components of the first unit 10. The first unit 10, which is a heat source side unit, is installed on the roof of a building or around a building, and is connected to the second unit 20 and the fourth unit 40 via refrigerant connection pipes 1A, 1B, and 1C, a first branch unit 60, and a third branch unit 80, and constitutes a part of the first refrigerant circuit 1 (see Fig. 1).

[0033] The first unit 10 mainly includes a heat source side heat exchanger 11, a compressor 12, an expansion valve 13, two four-way switching valves 14 and 15 that configure a switching mechanism, and a fan 16.

[0034] The heat source side heat exchanger 11 is a heat exchanger that functions as a radiator or evaporator of the first refrigerant by exchanging heat between the first refrigerant and outdoor air (outdoor air).

[0035] The compressor 12 is a positive displacement compressor such as a rotary type or scroll type, which draws in a first refrigerant, compresses the drawn in first refrigerant, and discharges it.

[0036] The expansion valve 13 is an electric expansion valve that reduces the pressure of the first refrigerant, adjusts the flow rate of the first refrigerant, etc. The opening degree of the expansion valve 13 is controlled by the control unit 101 shown in FIG.

[0037] The four-way switching valve 14 is an electrically operated valve that can be switched between a heat source side heat radiation state in which the heat source side heat exchanger 11 functions as a radiator for the first refrigerant, and a heat source side evaporation state in which the heat source side heat exchanger 11 functions as an evaporator for the first refrigerant. A first port 14a of the four-way switching valve 14 is connected to the discharge side of the compressor 12, a second port 14b is connected to the gas side of the heat source side heat exchanger 11, a third port 14c is connected to a third port 15c of the four-way switching valve 15, and a fourth port 14d is connected to the refrigerant connection pipe 1B. The four-way switching valve 14 can be switched between a state in which the first port 14a is connected to the second port 14b and the third port 14c is connected to the fourth port 14d (heat source side heat dissipation state), and a state in which the second port 14b is connected to the third port 14c and the first port 14a is connected to the fourth port 14d (heat source side evaporation state).

[0038] The four-way switching valve 15 is an electrically operated valve that can be switched between a state in which the discharge side of the compressor 12 is connected to the refrigerant connection pipe 1C and a state in which the discharge side of the compressor 12 is connected to the third port 14c of the four-way switching valve 14. A first port 15a of the four-way switching valve 15 is connected to the refrigerant connection pipe 1C, a second port 15b is connected to the discharge side of the compressor 12, a third port 15c is connected to the third port 15c of the four-way switching valve 14, and a fourth port 15d is connected to the suction side of the compressor 12.

[0039] In addition, the switching mechanism composed of two four-way switching valves 14, 15 is not limited to a mechanism composed of four-way switching valves, and may be configured to have the function of switching the flow direction of the first refrigerant in the same manner as described above, for example, by combining multiple solenoid valves.

[0040] (2-2) Unit 2 4A shows the components of the second unit 20. The second unit 20, which is a first cascade unit, is installed in the ceiling of each floor of a building, etc. One side of the second unit 20 is connected to the first unit 10 via refrigerant connection pipes 1A, 1B, 1C and a first branch unit 60, and the other side of the second unit 20 is connected to the third units 30A, 30B via refrigerant connection pipes 2A, 2B, 2C and second branch units 70A, 70B.

[0041] The second unit 20 mainly has a first cascade heat exchanger 21, a compressor 22, an expansion valve 23 on the first refrigerant circuit 1 side, an expansion valve 24 on the second refrigerant circuit 2 side, and two four-way switching valves 25, 26 that constitute a switching mechanism.

[0042] The first cascade heat exchanger 21 is a heat exchanger that functions as a radiator or an evaporator by performing heat exchange between the first refrigerant flowing through the first refrigerant circuit 1 and the second refrigerant flowing through the second refrigerant circuit 2. When the first cascade heat exchanger 21 functions as a radiator in the first refrigerant circuit 1, it functions as an evaporator in the second refrigerant circuit 2. Furthermore, when the first cascade heat exchanger 21 functions as an evaporator in the first refrigerant circuit 1, it functions as a radiator in the second refrigerant circuit 2.

[0043] The compressor 22 is a positive displacement compressor such as a rotary type or scroll type, which draws in a second refrigerant, compresses the drawn second refrigerant, and discharges it. The compressor 22 is a horizontal type compressor in which a compression element is disposed inside a horizontal casing. A horizontal type compressor is defined as a compressor in which the depth or width is the greatest among the height, depth, and width.

[0044] The expansion valve 23 is an electric expansion valve that reduces the pressure of the first refrigerant, adjusts the flow rate of the first refrigerant, etc. The opening degree of the expansion valve 23 is controlled by the control unit 101 via the first control unit 19.

[0045] The expansion valve 24 is an electric expansion valve that reduces the pressure of the second refrigerant, adjusts the flow rate of the second refrigerant, etc. The opening degree of the expansion valve 24 is controlled by the control unit 101 via the second control unit 29. In the air conditioning device 100, in a cooling operation mode described later, the expansion valve 24 causes the second refrigerant in a gas-liquid two-phase state to flow through the refrigerant communication pipe 2A, thereby performing two-phase transport of the refrigerant to the third units 30A and 30B.

[0046] The four-way switching valve 25 is an electrically operated valve that can be switched between a heat source side heat dissipation state in which the first cascade heat exchanger 21 functions as an evaporator for the first refrigerant, and a heat source side evaporation state in which the first cascade heat exchanger 21 functions as a radiator for the first refrigerant. A first port 25a of the four-way switching valve 25 is connected to the discharge side of the compressor 22, a second port 25b is connected to the gas side of the first cascade heat exchanger 21, a third port 25c is connected to a third port 26c of the four-way switching valve 26, and a fourth port 25d is connected to the refrigerant connection pipe 2B. The four-way switching valve 25 can be switched between a state in which the first port 25a is connected to the second port 5b and the third port 25c is connected to the fourth port 25d (heat source side heat dissipation state), and a state in which the second port 25b is connected to the third port 25c and the first port 25a is connected to the fourth port 25d (heat source side evaporation state).

[0047] The four-way switching valve 26 is an electrically operated valve capable of switching between a state in which the discharge side of the compressor 22 is connected to the refrigerant connection pipe 2C and a state in which the discharge side of the compressor 22 is connected to a third port 25c of the four-way switching valve 25. A first port 26a of the four-way switching valve 26 is connected to the refrigerant connection pipe 2C, a second port 26b is connected to the discharge side of the compressor 22, a third port 26c is connected to the third port 25c of the four-way switching valve 25, and a fourth port 26d is connected to the suction side of the compressor 22.

[0048] (2-3) First branch unit The first branching unit 60 is installed, for example, near the second unit 20. The first branching unit 60, together with the refrigerant connection pipes 1A, 1B, and 1C, is interposed between the second unit 20 and the first unit, and constitutes a part of the first refrigerant circuit 1.

[0049] The first branching unit 60 mainly has a first branching path including a branching unit switching valve 61, and a second branching path including a branching unit switching valve 62. The branching unit switching valve 61 is a solenoid valve that switches between communication and non-communication between the refrigerant connection pipe 1B and the first cascade heat exchanger 21. The branching unit switching valve 62 is a solenoid valve that switches between communication and non-communication between the refrigerant connection pipe 1C and the first cascade heat exchanger 21.

[0050] (2-4) 4th Unit 4B shows the components of the fourth unit 40. The fourth unit 40, which is a cascade unit, is installed in the ceiling of each floor of a building, etc. One side of the fourth unit 40 is connected to the first unit 10 via refrigerant connection pipes 1A, 1B, and 1C and a third branch unit 80, and the other side of the fourth unit 40 is connected to the fifth unit 50 via refrigerant connection pipes 3A, 3B, and 3C and a fourth branch unit 90.

[0051] The fourth unit 40 mainly has a second cascade heat exchanger 41, a compressor 42, an expansion valve 43 on the first refrigerant circuit 1 side, an expansion valve 44 on the third refrigerant circuit 3 side, and two four-way switching valves 45, 46 that configure a switching mechanism. In this embodiment, each component of the fourth unit 40 is similar to each component of the second unit, so a description thereof will be omitted.

[0052] (2-5) 3rd branch unit The third branching unit 80 is installed, for example, near the fourth unit 40 in the ceiling of each floor of a building, etc. The third branching unit 80 is interposed between the fourth unit 40 and the first unit together with the refrigerant connection pipes 1A, 1B, 1C, and constitutes a part of the first refrigerant circuit 1.

[0053] The third branching unit 80 mainly has a first branching passage including a branching unit switching valve 81 and a second branching passage including a branching unit switching valve 82. In this embodiment, each component of the third branching unit 80 is similar to each component of the first branching unit 60, and therefore description thereof will be omitted.

[0054] (2-6) Third Unit 5A shows the configuration of the third unit 30. The third units 30A, 30B, which are user-side units, are installed in the ceiling of each room in a building or the like by embedding or hanging, or are installed on a wall by hanging. The third units 30A, 30B are connected to the second unit 20 via the refrigerant connection pipes 2A, 2B, 2C and the second branch units 70A, 70B, and form a part of the second refrigerant circuit 2.

[0055] Next, the configuration of the third units 30A and 30B will be described. The third unit 30A has a utilization side heat exchanger 31A and an expansion valve 32A. The third unit 30B has a utilization side heat exchanger 31B and an expansion valve 32B. The utilization side heat exchangers 31A and 31B are heat exchangers that process the air conditioning load (heat load) in the room by exchanging heat between the second refrigerant and the indoor air. The opening degree of the expansion valves 32A and 32B is controlled by the control unit 101 via the third control unit 39.

[0056] (2-7) Second branch unit The second branch units 70A, 70B are installed, for example, near the third units 30A, 30B. The second branch units 70A, 70B, together with the refrigerant connection pipes 2A, 2B, 2C, are interposed between the third units 30A, 30B and the second unit 20, and constitute a part of the second refrigerant circuit 2. The second branch units 70A, 70B may be installed one for each of the third units 30A, 30B, which are the two user side units, or a plurality of user side units having the same cooling / heating switching timing may be connected to one branch unit.

[0057] The second branching units 70A, 70B mainly have a first branching path including branching unit switching valves 71A, 71B, and a second branching path including branching unit switching valves 72A, 72B. The branching unit switching valves 71A, 71B are solenoid valves that switch between communication and non-communication between the refrigerant connection pipe 2B and the utilization side heat exchangers 31A, 31B. The branching unit switching valves 72A, 72B are solenoid valves that switch between communication and non-communication between the refrigerant connection pipe 2C and the utilization side heat exchangers 31A, 31B.

[0058] (2-8) 5th Unit The plurality of fifth units 50A, 50B, which are user side units, are installed in the ceiling of each room in a building, etc., by embedding or hanging, or installed on a wall surface by hanging, etc. The fifth units 50A, 50B are connected to the fourth unit 40 via refrigerant connection pipes 3A, 3B, 3C and fourth branch units 90A, 90B, and constitute a part of the third refrigerant circuit 3.

[0059] The fifth unit 50A has a utilization side heat exchanger 51A and an expansion valve 52A. The fifth unit 50B has a utilization side heat exchanger 51B and an expansion valve 52B. In this embodiment, the components of the fifth units 50A and 50B are similar to those of the third unit 30, and therefore will not be described.

[0060] (2-9) 4th branch unit The fourth branching units 90A, 90B are installed, for example, near the fifth units 50A, 50B. The fourth branching units 90A, 90B, together with the refrigerant communication pipes 3A, 3B, 3C, are interposed between the fifth units 50A, 50B and the fourth unit 40, and constitute a part of the third refrigerant circuit 3.

[0061] The fourth branching units 90A, 90B mainly have a first branching passage including branching unit switching valves 91A, 91B and a second branching passage including branching unit switching valves 92A, 92B. Note that, in this embodiment, the components of the fourth branching units 90A, 90B are similar to the components of the second branching units 70A, 70B, and therefore will not be described.

[0062] (3) Air conditioner operation As operation modes of the air conditioner according to this embodiment, the operation of each component in a cooling operation mode in which all of the utilization units, the third units 30A, 30B and the fifth units 50A, 50B, are cooled, and a heating operation mode 60b in which all of the utilization units, the third units 30A, 30B and the fifth units 50A, 50B, are heated, will be described. The air conditioner 100 can be operated in a mixed cooling / heating operation mode in which some of the third units 30A, 30B and the fifth units 50A, 50B are operated in cooling operation, while some or all of the remaining units are operated in heating operation. The operation of the air conditioner 100 in the two operation modes will be described below.

[0063] (3-1) Cooling operation mode A cooling operation mode in which all of the third units 30A, 30B and the fifth units 50A, 50B, which are the utilization side units, are cooled, will be described. First, in the first refrigerant circuit 1, the heat source side heat exchanger 11 functions as a radiator of the first refrigerant. The opening degree of the expansion valve 13 is adjusted so as not to reduce the pressure of the refrigerant as much as possible (for example, to be in a fully open state). The first refrigerant passes through the expansion valve 13 and flows to the second unit 20 and the fourth unit 40 via the first branch unit 60 or the third branch unit 80.

[0064] In the first branching unit 60, the branching unit switching valve 61 is closed and the branching unit switching valve 62 is opened to cause the first cascade heat exchanger 21 to function as an evaporator for the first refrigerant in the first refrigerant circuit 1. The first refrigerant evaporated in the first cascade heat exchanger 21 passes through the refrigerant connection pipe 1C and the four-way switching valve 15 and is sucked into the compressor 12. The opening degree of the expansion valve 23 is adjusted according to the cooling load of the first cascade heat exchanger 21.

[0065] In the third branching unit 80, the branching unit switching valve 81 is closed and the branching unit switching valve 82 is opened to cause the second cascade heat exchanger 41 to function as an evaporator for the first refrigerant in the first refrigerant circuit 1. The first refrigerant evaporated in the second cascade heat exchanger 41 passes through the refrigerant connection pipe 1C and the four-way switching valve 15 and is sucked into the compressor 12. The opening degree of the expansion valve 43 is adjusted according to the cooling load of the second cascade heat exchanger 41.

[0066] In the second refrigerant circuit 2, the first cascade heat exchanger 21 functions as a radiator for the second refrigerant, and the expansion valve 24 is adjusted in opening degree so as not to reduce the pressure of the second refrigerant as much as possible (for example, to be in a fully open state). The second refrigerant passes through the expansion valve 24 and flows to the third units 30A, 30B via the second branch units 70A, 70B.

[0067] In the second branching unit 70A, the branching unit switching valve 71A is closed and the branching unit switching valve 72A is opened to cause the utilization side heat exchanger 71A to function as an evaporator of the second refrigerant in the second refrigerant circuit 2. The first refrigerant evaporated in the utilization side heat exchanger 71A passes through the refrigerant connection pipe 2C and the four-way switching valve 26 and is sucked into the compressor 22. The opening degree of the expansion valve 32A is adjusted according to the cooling load of the utilization side heat exchanger 71A.

[0068] In the second branching unit 70B, the branching unit switching valve 71B is closed and the branching unit switching valve 72B is opened to cause the utilization side heat exchanger 31B to function as an evaporator of the second refrigerant in the second refrigerant circuit 2. The first refrigerant evaporated in the utilization side heat exchanger 71B passes through the refrigerant connection pipe 2C and the four-way switching valve 26 and is sucked into the compressor 22. The opening degree of the expansion valve 32B is adjusted according to the cooling load of the utilization side heat exchanger 31B.

[0069] In the third refrigerant circuit 3, the third refrigerant circulates in the same manner as in the second refrigerant circuit 2. A description thereof will be omitted here.

[0070] (3-2) Heating operation mode In a heating operation mode in which all of the third units 30A, 30B and the fifth units 50A, 50B are heated, in the first refrigerant circuit 1, the first refrigerant discharged from the compressor 12 flows from the four-way switching valve 14 to the refrigerant connection pipe 1B, and then flows from the first branch unit 60 or the third branch unit 80 to the second unit 20 and the fourth unit 40.

[0071] In the first branching unit 60, the branching unit switching valve 61 is opened and the branching unit switching valve 62 is closed to cause the first cascade heat exchanger 21 to function as a radiator for the first refrigerant. The first refrigerant condensed in the first cascade heat exchanger 21 flows through the expansion valve 13 to the heat source side heat exchanger 11, and the first refrigerant evaporated therein is sucked into the compressor 12 through the first and four-way switching valves 14, 15. The opening degree of the expansion valve 13 is adjusted so as to reduce the pressure of the first refrigerant. The opening degree of the expansion valve 23 is adjusted according to the heating load of the first cascade heat exchanger 21.

[0072] In the third branching unit 80, the branching unit switching valve 81 is opened and the branching unit switching valve 82 is closed to cause the second cascade heat exchanger 41 to function as a radiator for the first refrigerant. The second refrigerant condensed in the second cascade heat exchanger 41 flows through the expansion valve 13 to the heat source side heat exchanger 11, and the first refrigerant evaporated therein is sucked into the compressor 12 through the first and four-way switching valves 14, 15. The opening degree of the expansion valve 43 is adjusted according to the heating load of the second cascade heat exchanger 41.

[0073] In the second refrigerant circuit, the second refrigerant discharged from the compressor 22 flows from the four-way switching valve 25 to the refrigerant connection pipe 2B, and then flows from the second branching units 70A, 70B to the third units 30A, 30B.

[0074] In the second branching unit 70A, the branching unit switching valve 71A is opened and the branching unit switching valve 72A is closed to make the utilization side heat exchanger 31A function as a radiator of the second refrigerant. The second refrigerant condensed in the utilization side heat exchanger 31A flows through the expansion valve 32A to the first cascade heat exchanger 21, where the evaporated second refrigerant is sucked into the compressor 22 through the first and four-way switching valves 25 and 26. The opening degree of the expansion valve 24 is adjusted so as to reduce the pressure of the second refrigerant. The opening degree of the expansion valve 32A is adjusted according to the heating load of the utilization side heat exchanger 31A.

[0075] In the branch unit 70B, the branch unit switching valve 71B is opened and the branch unit switching valve 72B is closed to make the utilization side heat exchanger 31B function as a radiator of the second refrigerant. The second refrigerant condensed in the utilization side heat exchanger 31B flows through the expansion valve 32B to the first cascade heat exchanger 21, where the evaporated second refrigerant is sucked into the compressor 22 through the first and four-way switching valves 25 and 26. The opening degree of the expansion valve 24 is adjusted so as to reduce the pressure of the second refrigerant. The opening degree of the expansion valve 32B is adjusted according to the heating load of the utilization side heat exchanger 31B.

[0076] In the third refrigerant circuit 3, the third refrigerant circulates in the same manner as in the second refrigerant circuit 2. A description thereof will be omitted here.

[0077] (4) Features (4-1) The air conditioner 100 as a refrigerant cycle system in this embodiment includes a first refrigerant circuit 1 and a second refrigerant circuit 2. The first refrigerant circuit 1 is a vapor compression refrigeration cycle. The second refrigerant circuit 2 is a vapor compression refrigeration cycle. The first refrigerant circuit 1 has a heat source side heat exchanger 11 as a first heat exchanger, a compressor 12 as a first compressor, and a first cascade heat exchanger 21. The second refrigerant circuit 2 has a first cascade heat exchanger 21, a compressor 22 as a second compressor, and user side heat exchangers 31A and 31B as second heat exchangers. The heat source side heat exchanger 11 and the compressor 12 are housed in the first unit 10. The first cascade heat exchanger 21 and the compressor 22 are housed in the second unit 20. The user side heat exchangers 31A and 31B are housed in the third unit 30. The first unit 10, the second unit 20, and the third unit 30 are disposed apart from each other. The first cascade heat exchanger 21 exchanges heat between a first refrigerant flowing through the first refrigerant circuit 1 and a second refrigerant flowing through the second refrigerant circuit 2.

[0078] Conventionally, refrigerants used in refrigerant cycle systems may be flammable or toxic. When such refrigerants are used, the allowable amount of refrigerant per volume of each room in a building is limited. When the allowable amount of refrigerant per volume exceeds the limited amount, it is necessary to install a refrigerant leakage detection sensor, a shutoff valve for the refrigerant piping, etc., for safety reasons, which increases the equipment cost or installation cost of the refrigerant cycle system.

[0079] The air conditioner 100 as a refrigerant cycle system disclosed in the present disclosure can reduce the amount of refrigerant per volume of each room by connecting the first refrigerant circuit 1 and the second refrigerant circuit 2 using the first cascade heat exchanger 21. This can reduce the number of cases where safety measures are required.

[0080] (4-2) The air conditioning device 100 further includes a second cascade heat exchanger 41, a compressor 42 as a third compressor, utilization side heat exchangers 51A and 51B as the third heat exchanger, a fourth unit 40, and a fifth unit 50. In the air conditioning device 100, the second cascade heat exchanger 41, the compressor 42, and the utilization side heat exchangers 51A and 51B are connected to configure a third refrigerant circuit 3. The second cascade heat exchanger 41 and the compressor 42 are housed in the fourth unit 40. The utilization side heat exchangers 51A and 51B are housed in the fifth unit 50. The first unit 10, the fourth unit 40, and the fifth unit 50 are disposed apart from each other. The second cascade heat exchanger 41 exchanges heat between the first refrigerant flowing through the first refrigerant circuit 1 and the third refrigerant flowing through the third refrigerant circuit 3.

[0081] For example, by installing the second units 20 separately for each floor, it is possible to separate the refrigerant circuits for each floor, which further reduces the number of cases where safety measures are required.

[0082] (4-3) The air conditioning apparatus 100 further includes a first branching unit 60 between the first unit 10 and the second unit 20, as a first refrigerant flow path switching unit for switching the flow path of the first refrigerant flowing through the first refrigerant circuit 1.

[0083] In addition, the air conditioning apparatus 100 further includes second branching units 70A, 70B between the second unit 20 and the third units 30A, 30B as second refrigerant flow path switching units for switching the flow path of the second refrigerant flowing through the second refrigerant circuit 2.

[0084] The air conditioning apparatus 100 further includes a third branching unit 80 between the first unit 10 and the third unit 30 for switching the flow path of the first refrigerant flowing through the first refrigerant circuit 1.

[0085] The air conditioning apparatus 100 further includes fourth branching units 90A, 90B for switching the flow path of the third refrigerant flowing through the third refrigerant circuit 3 between the fourth unit 40 and the fifth units 50A, 50B.

[0086] This allows the air conditioning apparatus 100 to perform a mixed cooling and heating operation in which heating and cooling are selected for each of the utilization side units 30A, 30B, 50A, 50B.

[0087] (4-4) The second refrigerant flowing through the second refrigerant circuit 2 and the third refrigerant flowing through the third refrigerant circuit 3 of the air conditioner 100 are R32.

[0088] R32 is a refrigerant that is commonly used in air conditioners because it has little impact on the environment. However, R32 is slightly flammable, and it is necessary to ensure safety in the unlikely event that it leaks due to an unforeseen event such as a natural disaster.

[0089] The air conditioning apparatus 100 of the present embodiment is provided with the first cascade heat exchanger 21 and the second cascade heat exchanger 41, thereby making it possible to further reduce the amount of refrigerant flowing through each of the refrigerant circuits 1, 2, and 3. This makes it possible to ensure greater safety.

[0090] (4-5) The second refrigerant circuit 2 of the air conditioner 100 has an expansion valve 24 as an expansion mechanism, and the fluid flowing into the expansion valve 24 is in a two-phase gas-liquid state. The third refrigerant circuit 3 has an expansion valve 44, and the fluid flowing into the expansion valve 44 is in a two-phase gas-liquid state. This allows the amount of refrigerant flowing through each of the refrigerant circuits 2, 3 to be further reduced.

[0091] (4-6) The compressor 22 housed in the second unit 20 of the air conditioning apparatus 100 of this embodiment is of a horizontally placed type. Also, the compressor 42 housed in the fourth unit 40 is of a horizontally placed type.

[0092] The second unit 20 and the fourth unit 40 may be installed in the ceiling of each floor of a building. A horizontal compressor is defined as a compressor in which the depth or width is the greatest among the height, depth, and width. The horizontal compressors 22, 42 are suitable for installation in a low space such as the ceiling.

[0093] (5) Variations (5-1) The first refrigerant circuit 1, the second refrigerant circuit 2, and the third refrigerant circuit 3 of the air conditioning apparatus 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 shown in the present 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.

[0094] The first, second and third refrigerants charged in 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 any 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.

[0095] The second and third refrigerants of the air conditioning apparatus 100 may be flammable or toxic refrigerants.

[0096] By including the first cascade heat exchanger 21 and the second cascade heat exchanger 41, the air conditioning device 100 can reduce the amount of refrigerant flowing through each of the refrigerant circuits 1, 2, and 3. This can ensure greater safety. In addition, it is possible to reuse an existing refrigerant cycle system.

[0097] (5-2) The refrigerant cycle system of this embodiment has been described in relation to the air conditioner 100, but it can also be applied to an air conditioner 200 as shown in FIG.

[0098] The air conditioning apparatus 200 may further include a use side heat exchanger 211A as a fourth heat exchanger, and a sixth unit 210A that houses the use side heat exchanger 211A. The use side heat exchanger 211A is a heat exchanger different from the heat source side heat exchanger 211, the first cascade heat exchanger 221, and the second cascade heat exchanger 241 that serve as the first heat exchangers in the first refrigerant circuit 201, and is used as a use side heat exchanger. The sixth unit 210A houses the use side heat exchanger 211A.

[0099] (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 described in the claims. [Explanation of symbols]

[0100] 1,201 1st refrigerant circuit 2 Second refrigerant circuit 3 Third refrigerant circuit 10,210 1st unit 11,211 1st heat exchanger 12 First compressor 20,220 2nd Unit 21,221 First cascade heat exchanger 22 Second compressor 30 Unit 1 31A,31B 2nd heat exchanger 32A, 32B Expansion mechanism 40,240 1st unit 41,241 Second cascade heat exchanger 42 Third compressor 50 Unit 1 51A,51B 3rd heat exchanger 60,260 First refrigerant flow path switching unit 70A, 70B Second refrigerant flow path switching unit 100 Refrigerant cycle system 200 Refrigerant cycle system 210A Unit 6 211A 4th heat exchanger [Prior art documents] [Patent documents]

[0101] [Patent Document 1] JP 2018-194260 A

Claims

1. A first refrigerant circuit (1, 201) which is a vapor compression refrigeration cycle, A second refrigerant circuit (2) which is a vapor compression refrigeration cycle, Comprising, The first refrigerant circuit (1, 201) has a first heat exchanger (11, 211), a first compressor (12), and a first cascade heat exchanger (21, 221), The second refrigerant circuit (2) has a first cascade heat exchanger (21, 221), a second compressor (22), and a second heat exchanger (31A, 31B), The first heat exchanger (11, 211) and the first compressor (12) are housed in a first unit (10, 210), The first cascade heat exchanger (21, 221) and the second compressor (22) are housed in a second unit (20, 220), The second heat exchanger (31A, 31B) is housed in a third unit (30A, 30B), The first unit (10, 210), the second unit (20, 220), and the third unit (30A, 30B) are arranged separately from each other, The first cascade heat exchanger (21, 221) performs heat exchange between the first refrigerant flowing through the first refrigerant circuit (1, 201) and the second refrigerant flowing through the second refrigerant circuit (2), An air conditioner (100, 200).

2. A second cascade heat exchanger (41, 241), a third compressor (42), a third heat exchanger (51A, 51B), a fourth unit (40, 240), a fifth unit (50A, 50B), Further comprising, The second cascade heat exchanger (41, 241), the third compressor (42), and the third heat exchanger (51A, 51B) are connected to form a third refrigerant circuit (3), The second cascade heat exchanger (41, 241) and the third compressor (42) are housed in the fourth unit (40, 240), The third heat exchanger (51A, 51B) is housed in the fifth unit (50A, 50B), The first unit (10, 210), the fourth unit (40, 240), and the fifth unit (50A, 50B) are arranged separately from each other, The second cascade heat exchanger (41, 241) causes heat exchange between the first refrigerant and the third refrigerant flowing through the third refrigerant circuit (3), The air conditioner (100, 200) according to Claim 1.

3. Between the first unit (10, 210) and the second unit (20, 220), a first refrigerant flow path switching unit (60, 260) for switching the flow path of the first refrigerant is further provided. The air conditioner (100, 200) according to claim 2.

4. Between the second unit (20, 220) and the third unit (30A, 30B), a second refrigerant flow path switching unit (70A, 70B) for switching the flow path of the second refrigerant is further provided. The air conditioner (100, 200) according to any one of claims 1 to 3.

5. The second refrigerant flowing through the second refrigerant circuit (2) includes flammability or toxicity. The air conditioner (100, 200) according to any one of claims 1 to 4.

6. The first refrigerant and the second refrigerant are any one of HFC refrigerants, HFO refrigerants, natural refrigerants, or a mixed refrigerant containing two or more of HFC refrigerants, HFO refrigerants, natural refrigerants, and CFC ３ I. The air conditioner (100, 200) according to any one of claims 1 to 5.

7. The first refrigerant is R32. The air conditioner (100, 200) according to any one of claims 1 to 6.

8. The first refrigerant and the second refrigerant are R32. The air conditioner (100, 200) according to any one of claims 1 to 7.

9. The second compressor (22) accommodated in the second unit (20, 220) is a horizontally placed type. The air conditioner (100, 200) according to any one of claims 1 to 8.

10. The second refrigerant circuit (2) has an expansion mechanism (32A, 32B). The second refrigerant flowing into the expansion mechanism (32A, 32B) is in a gas-liquid two-phase state. The air conditioner (100, 200) according to any one of claims 1 to 9.

11. The first refrigerant circuit (201) includes a fourth heat exchanger (211A) used as a utilization-side heat exchanger. A sixth unit (210A) that houses the fourth heat exchanger (211A). It is further provided with. The air conditioner (200) according to any one of claims 1 to 10.

12. The first cascade heat exchanger (21, 221) performs heat exchange between the first refrigerant discharged from the first compressor and the second refrigerant discharged from the second compressor. The air conditioner (100, 200) according to any one of claims 1 to 11.

13. The first refrigerant circuit further has a four-way switching valve (14) capable of switching between a heat source side heat dissipation state in which the first heat exchanger functions as a radiator for the first refrigerant and a heat source side evaporation state in which the first heat exchanger functions as an evaporator for the first refrigerant. The first unit further houses the four-way switching valve. The air conditioner (100, 200) according to any one of claims 1 to 12.

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