Refrigerant circulation device

Abstract

If the size of the shutoff valve is excessive, the manufacturing cost increases. An air conditioning device (1) that circulates a micro-flammable refrigerant in a refrigerant circuit (10) includes a first shutoff valve (71a) and a second shutoff valve (68a) that suppress leakage of the refrigerant to a prescribed space. The first shutoff valve (71a) and the second shutoff valve (68a) have a leakage amount of air in a shutoff state, when the fluid is air at 20°C and the pressure difference before and after is 1 MPa, of greater than 300 (cm 3 / min) and less than 300 x R (cm 3 / min). Here, R = (p md x V md x A d ) / (C r x (2 x ΔP r / p 1r ) 0.5 x A v x p 1rl + A v x (2 / (l+1)) ((λ+1) / 2(λ‑1)) x (l x P 1r x p 1rg ) 0.5 ).

Description

TECHNICAL FIELD

[0001] The present application relates to a refrigerant cycle device. BACKGROUND

[0002] In the guideline "Guideline for Safety Assurance Facilities at the Time of Refrigerant Leakage of Commercial Air Conditioners Using Microflammable (A2L) Refrigerants" (JRA GL-16:2017) of the Japan Refrigeration and Air-Conditioning Industry Association issued on September 1, 2017, the following provisions are made: provisions for safety assurance against leakage of refrigerants filled in commercial air conditioners using microflammable (A2L) refrigerants, in relation to air conditioning system selection and construction and ventilation and the like construction countermeasures. Refrigerants classified as microflammable (A2L) refrigerants are, for example, R32, R1234yf, or R1234ze.

[0003] The above guideline is a guideline compiled by the Japan Refrigeration and Air-Conditioning Industry Association in order to ensure safety in terms of microflammable (A2L) refrigerants, which are refrigerants useful from the viewpoint of preventing global warming. In the guideline, various aspects such as detectors that detect leakage of refrigerants, alarm devices, safety shutoff valves, and the like are described. SUMMARY

[0004] Technical problem to be solved by the invention

[0005] In the above guideline, in the case where a safety shutoff valve is adopted as a safety countermeasure, it is prescribed that the safety shutoff valve must be provided at an appropriate position in the refrigerant circuit in which shutoff is performed, so that the maximum concentration of refrigerant at the time of leakage of refrigerant in the living room (room) that is the object at the time of leakage of refrigerant is below the value of 1 / 4 of LFL. Furthermore, it is prescribed that the refrigerant circuit must be shutoff in accordance with the signal of the detector that detects leakage of refrigerant.

[0006] In addition, the safety shutoff valve is a valve that shutoffs refrigerant that leaks from the refrigerant circuit to the refrigerant leakage space at the time of leakage of refrigerant. LFL (Lower Flammability Limit) is the minimum concentration of refrigerant that can propagate a flame in a state in which refrigerant and air are uniformly mixed, which is prescribed in ISO 817. The maximum concentration at the time of leakage of refrigerant is a value obtained by dividing the total amount of refrigerant of the refrigerant circuit by the volume of the space in which refrigerant is retained (a value obtained by multiplying the floor area by the leakage height).

[0007] For the specifications of the safety shutoff valve, "Appendix A (Provisions) Specifications of Safety Shutoff Valves" of the above guideline is prepared, and the prescribed specifications must be satisfied. One of the specifications of the safety shutoff valve that must be satisfied is the leakage amount at the time of closing. Specifically, when the fluid is air and the pressure difference before and after the safety shutoff valve is 1 MPa, 300 (cm 3The following values ​​( / min) are specified as the leakage rate that a safety shut-off valve should meet when closed.

[0008] It is believed that if a safety shut-off valve meets the above specifications, the amount of refrigerant leakage when closed is very small, reliably ensuring safety. However, depending on the location of the refrigerant circuit and the type of refrigerant, the above specifications may be excessive, potentially causing an unnecessary increase in the manufacturing cost of the refrigerant circulation system.

[0009] Technical solutions adopted to solve technical problems

[0010] The inventors of this application have discovered that even when using a valve that does not meet the specifications specified in the above guidelines as a safety shut-off valve, the safety requirements can still be met depending on the conditions.

[0011] The first-view refrigerant circulation device is a device that circulates a slightly flammable refrigerant in a refrigerant circuit, and includes a first shut-off valve, a second shut-off valve, a detection unit, and a control unit. The first and second shut-off valves are located on opposite sides of a first section of the refrigerant circuit. The detection unit detects refrigerant leakage from the first section of the refrigerant circuit into a designated space. When the detection unit detects refrigerant leakage into the designated space, the control unit sets the first and second shut-off valves to a shut-off state, suppressing refrigerant leakage into the designated space. The leakage amounts of the first and second shut-off valves in the shut-off state, with the fluid being air at 20°C and a pressure difference of 1 MPa, are respectively...

[0012] Greater than 300 (cm) 3 / min),

[0013] Less than 300×R (cm) 3 / min).

[0014] in,

[0015] R=(ρ md ×V md ×A d ) / (C r ×(2×ΔP r / ρ 1rl ) 0.5 ×A v ×ρ 1rl +A v ×(2 / (λ+1)) ((λ+1) / 2(λ-1)) ×(λ×P 1r ×ρ 1rg ) 0.5 ).

[0016] Av is the valve gap cross-sectional area (m²) of the first and second shut-off valves under their respective shut-off states. 2 ).

[0017] ρ 1rl is the mass concentration of the refrigerant in the liquid phase (kg / m 3 ).

[0018] ρ 1rg is the mass concentration of the refrigerant in the gas phase (kg / m 3 ).

[0019] P 1r is the pressure of the refrigerant on the upstream side of each of the first and second shutoff valves (MPa).

[0020] λ is the specific heat ratio of the refrigerant.

[0021] ρ md is the mass concentration of the mixed gas of air and refrigerant flowing through the gap of the door that separates the inside and outside of the prescribed space (kg / m 3 ).

[0022] V md is the velocity of the mixed gas of air and refrigerant flowing through the gap of the door that separates the inside and outside of the prescribed space (m / s).

[0023] A d is the area of the gap of the door that separates the inside and outside of the prescribed space (m 2 ).

[0024] ΔP r is the pressure difference between the inside and outside of the hole of the portion from which the refrigerant is leaking (Pa).

[0025] C r is the flow coefficient of the refrigerant when the refrigerant in the liquid phase flows through the hole of the portion from which the refrigerant is leaking, and is 0.6.

[0026] Further, the leakage amount at the time of shutoff is the same as the leakage amount at the time of closing in the above-mentioned guideline.

[0027] In the refrigerant circulating device of the first aspect, the above-mentioned first and second shutoff valves are employed. The leakage amount at the time of shutoff of the first and second shutoff valves is greater than 300 (cm 3 / min) and less than 300 x R (cm 3 / min). For example, in a case where R32 is used as the refrigerant and the first portion of the refrigerant circuit is located at a height of 2.2 m from the floor of the prescribed space, if 1 / 4 of the LFL (lower flammable limit) prescribed in ISO 817 is set as the allowable refrigerant concentration of the prescribed space, R = 1.96. In this case, the leakage amount at the time of shutoff of the first shutoff valve and the second shutoff valve (the leakage amount of air when the fluid is air at 20°C and the pressure difference before and after is 1 MPa, as described above) is greater than 300 (cm 3 / min) and less than 300 x 1.96 (cm 3 / min). In other words, as the first shutoff valve and the second shutoff valve, it is not necessary to use an expensive valve having a leakage amount at the time of shutoff of 300 (cm 3 / min) or less, and, for example, a cheap valve having a leakage amount at the time of shutoff of about 550 (cm 3 / min) can be used.

[0028] Thus, in the refrigerant circulating device of the first aspect, a cheaper valve can be used as the first shutoff valve and the second shutoff valve, and the manufacturing cost can be suppressed.

[0029] The refrigerant circulating device of the second aspect is the refrigerant circulating device of the first aspect, and R is 1 < R < 10.1.

[0030] According to the Japan Refrigeration and Air-Conditioning Industry Association, which issues the above-mentioned guideline, refrigerant circulating devices in which actual refrigerant leakage has occurred on the market are collected, and the hole diameter of the refrigerant leakage site is confirmed, and the maximum hole diameter is 0.174 mm (see the Japan Refrigeration and Air-Conditioning Industry Association, "Risk Evaluation Report for Multi-Unit Air Conditioners for Buildings Using Micro-Flammable Refrigerants" (issued on September 20, 2017)).

[0031] The area of the hole having this hole diameter is 10.1 times the valve gap cross-sectional area in the shutoff state of the first shutoff valve and the second shutoff valve when the leakage amount at the time of shutoff is 300 (cm 3 / min). Therefore, if R reaches 10.1 or more, and thus the leakage amount at the time of shutoff of the first shutoff valve and the second shutoff valve reaches 300 x 10.1 (cm 3 / min), the valve gap cross-sectional area becomes the same as or more than the hole area of the refrigerant leakage site. In this way, it is virtually impossible to perform shutoff of the refrigerant, and the significance of providing the first shutoff valve and the second shutoff valve is lost.

[0032] In view of the above, in the refrigerant circulating device of the second aspect, 10.1 is set as the upper limit of R.

[0033] The refrigerant circulation device of the third viewpoint is a refrigerant circulation device of the first or second viewpoint, and the refrigerant circuit has a utilization side circuit, a heat source side circuit, and a liquid refrigerant connecting pipe and a gaseous refrigerant connecting pipe connecting the utilization side circuit and the heat source side circuit. The utilization side circuit is a part of the refrigerant circuit of a utilization side unit located in or connected to a specified space. The heat source side circuit is a part of the refrigerant circuit of a heat source side unit. The first part of the refrigerant circuit, which is the object of detection for refrigerant leakage by the detection unit, is the utilization side circuit. A first shut-off valve is installed in the liquid refrigerant connecting pipe. A second shut-off valve is installed in the gaseous refrigerant connecting pipe.

[0034] The refrigerant circulation device of the fourth viewpoint is any of the refrigerant circulation devices of the first to third viewpoints, and the slightly flammable refrigerant is a refrigerant that is classified as slightly flammable (A2L) in ISO 817. Attached Figure Description

[0035] Figure 1 This is a diagram showing a schematic structure of an air conditioning unit as one embodiment of a refrigerant circulation device.

[0036] Figure 2 This is a diagram showing the refrigerant circuit of an air conditioning unit.

[0037] Figure 3 This is a diagram showing a room equipped with air conditioning.

[0038] Figure 4 This is a control block diagram of an air conditioning unit.

[0039] Figure 5 This is a diagram illustrating the control process used to address refrigerant leaks. Detailed Implementation

[0040] (1) Structure of air conditioning unit

[0041] like Figure 1 and Figure 2 As shown, an air conditioning unit 1, as one embodiment of a refrigerant circulation device, is a device for cooling and heating rooms in buildings such as skyscrapers using a vapor compression refrigeration cycle. The air conditioning unit 1 mainly includes a heat source side unit 2, multiple user side units 3a, 3b, 3c, and 3d, relay units 4a, 4b, 4c, and 4d connected to each user side unit 3a, 3b, 3c, and 3d, refrigerant connecting pipes 5 and 6, and a control unit 19 (see reference). Figure 4). The plurality of utilization-side units 3a, 3b, 3c, 3d are connected in parallel with respect to the heat-source-side unit 2. The refrigerant communication pipes 5, 6 connect the heat-source-side unit 2 and the utilization-side units 3a, 3b, 3c, 3d via the relay units 4a, 4b, 4c, 4d. The control portion 19 controls the constituent devices of the heat-source-side unit 2, the utilization-side units 3a, 3b, 3c, 3d, and the relay units 4a, 4b, 4c, 4d. Also, as shown in Figure 2 As shown in FIG. 1, the air-conditioning apparatus 1 is provided with a refrigerant circuit 10 of a vapor compression type. The refrigerant circuit 10 is constituted by connecting a heat-source-side circuit 222 of a heat-source-side unit 2, utilization-side circuits 3aa, 3bb, 3cc, 3dd of utilization-side units 3a, 3b, 3c, 3d, liquid connection pipes 61a, 61b, 61c, 61d and gas connection pipes 62a, 62b, 62c, 62d of relay units 4a, 4b, 4c, 4d, and refrigerant communication pipes 5, 6.

[0042] R32 is filled in the refrigerant circuit 10 as a refrigerant. When R32 leaks from the refrigerant circuit 10 to the room SP (refer to FIG. 1) and thus the refrigerant concentration in the room SP becomes high, there is a possibility that a combustion accident occurs due to the flammability of the refrigerant. It is required to prevent such a combustion accident. Figure 3

[0043] Also, the air-conditioning apparatus 1 switches the utilization-side units 3a, 3b, 3c, 3d to a cooling operation or a heating operation by a switching mechanism 22 possessed by the heat-source-side unit 2.

[0044] (1-1) Refrigerant communication pipes

[0045] The liquid refrigerant communication pipe 5 mainly has a confluence pipe portion extending from the heat-source-side unit 2, first branched pipe portions 5a, 5b, 5c, 5d branched in plurality (four in this case) in front of the relay units 4a, 4b, 4c, 4d, and second branched pipe portions 5aa, 5bb, 5cc, 5dd connecting the relay units 4a, 4b, 4c, 4d and the utilization-side units 3a, 3b, 3c, 3d.

[0046] Also, the gas refrigerant communication pipe 6 mainly has a confluence pipe portion extending from the heat-source-side unit 2, first branched pipe portions 6a, 6b, 6c, 6d branched in plurality (four in this case) in front of the relay units 4a, 4b, 4c, 4d, and second branched pipe portions 6aa, 6bb, 6cc, 6dd connecting the relay units 4a, 4b, 4c, 4d and the utilization-side units 3a, 3b, 3c, 3d.

[0047] (1-2) Utilization-side units ​

[0048] The utilization-side units 3a, 3b, 3c, 3d are provided in a room of a building or the like. As described above, the utilization-side units 3a, 3b, 3c, 3d are connected with the heat-source-side unit 2 via the liquid refrigerant communication pipe 5, the gas refrigerant communication pipe 6, and the relay units 4a, 4b, 4c, 4d to constitute a part of the refrigerant circuit 10.

[0049] Next, the structure of the utilization-side unit 3a, 3b, 3c, 3d will be described. Note that the utilization-side unit 3a and the utilization-side units 3b, 3c, 3d have the same structure, and therefore, here, only the structure of the utilization-side unit 3a will be described, and for the structures of the utilization-side units 3b, 3c, 3d, "b", "c", "d" will be respectively added in place of "a" indicating each part of the utilization-side unit 3a, and the description of each part will be omitted.

[0050] The utilization-side unit 3a mainly has a utilization-side expansion valve 51a and a utilization-side heat exchanger 52a. Further, the utilization-side unit 3a has a utilization-side liquid refrigerant pipe 53a connecting a liquid-side end of the utilization-side heat exchanger 52a with the liquid refrigerant communication pipe 5 (here, the branch pipe portion 5aa), and a utilization-side gas refrigerant pipe 54a connecting a gas-side end of the utilization-side heat exchanger 52a with the gas refrigerant communication pipe 6 (here, the second branch pipe portion 6aa). A utilization-side circuit 3aa of the utilization-side unit 3a is constituted by these utilization-side liquid refrigerant pipe 53a, utilization-side expansion valve 51a, utilization-side heat exchanger 52a, and utilization-side gas refrigerant pipe 54a.

[0051] The utilization-side expansion valve 51a is an electric expansion valve capable of adjusting the flow rate of the refrigerant flowing through the utilization-side heat exchanger 52a while reducing the pressure of the refrigerant, and is provided to the utilization-side liquid refrigerant pipe 53a.

[0052] The utilization-side heat exchanger 52a is a heat exchanger functioning as an evaporator of the refrigerant to cool the indoor air, or functioning as a radiator of the refrigerant to heat the indoor air. Here, the utilization-side unit 3a has a utilization-side fan 55a. The utilization-side fan 55a supplies the indoor air, which is a cooling source or a heating source of the refrigerant flowing through the utilization-side heat exchanger 52a, to the utilization-side heat exchanger 52a. The utilization-side fan 55a is driven by a utilization-side fan motor 56a.

[0053] The utilization-side unit 3a is provided with various sensors. Specifically, the utilization-side unit 3a is provided with a utilization-side heat-exchange liquid-side sensor 57a that detects the temperature of the refrigerant at the liquid-side end of the utilization-side heat exchanger 52a, a utilization-side heat-exchange gas-side sensor 58a that detects the temperature of the refrigerant at the gas-side end of the utilization-side heat exchanger 52a, and an indoor air sensor 59a that detects the temperature of the indoor air drawn into the utilization-side unit 3a. Further, the utilization-side unit 3a is provided with a refrigerant leakage detection section 79a that detects leakage of the refrigerant. The refrigerant leakage detection section 79a can employ, for example, a semiconductor gas sensor, or a detection section that detects a sharp decrease in the pressure of the refrigerant in the utilization-side unit 3a. In the case of employing a semiconductor gas sensor, it is connected to the utilization-side control section 93a (see FIG. 9). In the case of employing a detection section that detects a sharp decrease in the pressure of the refrigerant, a pressure sensor is provided to the refrigerant piping, and a detection algorithm that judges refrigerant leakage based on changes in the sensor value of the pressure sensor is included in the utilization-side control section 93a. Figure 4 ). In the case of employing a detection section that detects a sharp decrease in the pressure of the refrigerant, a pressure sensor is provided to the refrigerant piping, and a detection algorithm that judges refrigerant leakage based on changes in the sensor value of the pressure sensor is included in the utilization-side control section 93a.

[0054] Further, the refrigerant leakage detection section 79a is provided to the utilization-side unit 3a, but is not limited thereto, and can be provided to a remote controller that operates the utilization-side unit 3a, an indoor space that is air-conditioned by the utilization-side unit 3a, or the like.

[0055] (1-3) Heat-source-side unit

[0056] The heat-source-side unit 2 is provided to the outside of a building or the like, such as a roof or the ground. As described above, the heat-source-side unit 2 is connected to the utilization-side units 3a, 3b, 3c, 3d via the liquid refrigerant communication pipe 5, the gas refrigerant communication pipe 6, and the relay units 4a, 4b, 4c, 4d, and constitutes a part of the refrigerant circuit 10.

[0057] The heat-source side unit 2 mainly has the compressor 21 and the heat-source side heat exchanger 23. Further, the heat-source side unit 2 has a switching mechanism 22 which is a cold-heat switching mechanism that switches between a cooling operation state in which the heat-source side heat exchanger 23 functions as a heat sink for refrigerant and the utilization side heat exchangers 52a, 52b, 52c, 52d function as evaporators for refrigerant, and a heating operation state in which the heat-source side heat exchanger 23 functions as an evaporator for refrigerant and the utilization side heat exchangers 52a, 52b, 52c, 52d function as heat sinks for refrigerant. The switching mechanism 22 and the suction side of the compressor 21 are connected by a suction refrigerant pipe 31. A tank 29 that temporarily stores refrigerant sucked into the compressor 21 is provided in the suction refrigerant pipe 31. The discharge side of the compressor 21 is connected to the switching mechanism 22 by a discharge refrigerant pipe 32. The switching mechanism 22 and the gas side end of the heat-source side heat exchanger 23 are connected by a first heat-source side gas refrigerant pipe 33. The liquid side end of the heat-source side heat exchanger 23 and the liquid refrigerant communication pipe 5 are connected by a heat-source side liquid refrigerant pipe 34. A liquid side shutoff valve 27 is provided in the connection portion of the heat-source side liquid refrigerant pipe 34 to which the liquid refrigerant communication pipe 5 is connected. The switching mechanism 22 and the gas refrigerant communication pipe 6 are connected by a second heat-source side gas refrigerant pipe 35. A gas side shutoff valve 28 is provided in the connection portion of the second heat-source side gas refrigerant pipe 35 to which the gas refrigerant communication pipe 6 is connected. The liquid side shutoff valve 27 and the gas side shutoff valve 28 are, for example, manually opened and closed valves. During operation, the liquid side shutoff valve 27 and the gas side shutoff valve 28 are in an open state. The heat-source side circuit 222 of the heat-source side unit 2 is constituted by these suction refrigerant pipe 31, compressor 21, discharge refrigerant pipe 32, first heat-source side gas refrigerant pipe 33, heat-source side heat exchanger 23, heat-source side liquid refrigerant pipe 34, second heat-source side gas refrigerant pipe 35, and the like.

[0058] The compressor 21 is an apparatus for compressing refrigerant, for example, a hermetic type compressor in which a compression element (not shown) of a rotary type, scroll type, or the like volume type is rotated by a compressor motor 21a.

[0059] The switching mechanism 22 is an apparatus that can switch the flow of refrigerant in the refrigerant circuit 10, for example, is constituted by a four-way switching valve. In a case in which the heat-source side heat exchanger 23 functions as a heat sink for refrigerant and the utilization side heat exchangers 52a, 52b, 52c, 52d function as evaporators for refrigerant (hereinafter, referred to as "cooling operation state"), the switching mechanism 22 connects the discharge side of the compressor 21 and the gas side of the heat-source side heat exchanger 23 (refer to FIG. 2). Figure 2line) of the switching mechanism 22. Also, in a case where the heat-source-side heat exchanger 23 functions as an evaporator of the refrigerant and the utilization-side heat exchangers 52a, 52b, 52c, 52d function as radiators of the refrigerant (hereinafter, referred to as "cooling operation state"), the switching mechanism 22 connects the suction side of the compressor 21 and the gas side of the heat-source-side heat exchanger 23 (refer to the solid line of the first switching mechanism 22). Figure 2

[0060] The heat-source-side heat exchanger 23 is a heat exchanger that functions as a radiator of the refrigerant or functions as an evaporator of the refrigerant. Here, the heat-source-side unit 2 has a heat-source-side fan 24. The heat-source-side fan 24 sucks outdoor air into the heat-source-side unit 2 and discharges the outdoor air to the outside after the outdoor air exchanges heat with the refrigerant in the heat-source-side heat exchanger 23. The heat-source-side fan 24 is driven by a heat-source-side fan motor.

[0061] Also, in the air-conditioning apparatus 1, in the cooling operation, the refrigerant flows from the heat-source-side heat exchanger 23 to the utilization-side heat exchangers 52a, 52b, 52c, 52d that function as evaporators of the refrigerant through the liquid refrigerant communication pipe 5 and the relay units 4a, 4b, 4c, 4d. Also, in the air-conditioning apparatus 1, in the heating operation, the refrigerant flows from the compressor 21 to the utilization-side heat exchangers 52a, 52b, 52c, 52d that function as radiators of the refrigerant through the gas refrigerant communication pipe 6 and the relay units 4a, 4b, 4c, 4d. At the time of the cooling operation, a state where the switching mechanism 22 is switched to the cooling operation state, the heat-source-side heat exchanger 23 functions as a radiator of the refrigerant, and the refrigerant flows from the heat-source-side unit 2 side to the utilization-side unit 3a, 3b, 3c, 3d side through the liquid refrigerant communication pipe 5 and the relay units 4a, 4b, 4c, 4d is established. At the time of the heating operation, a state where the switching mechanism 22 is switched to the heating operation state, the refrigerant flows from the utilization-side unit 3a, 3b, 3c, 3d side to the heat-source-side unit 2 side through the liquid refrigerant communication pipe 5 and the relay units 4a, 4b, 4c, 4d, and the heat-source-side heat exchanger 23 functions as an evaporator of the refrigerant is established.

[0062] Also, here, the heat-source-side liquid refrigerant pipe 34 is provided with a heat-source-side expansion valve 25. The heat-source-side expansion valve 25 is an electric expansion valve that depressurizes the refrigerant at the time of the heating operation, and is provided in a portion of the heat-source-side liquid refrigerant pipe 34 that is close to the liquid side end of the heat-source-side heat exchanger 23.

[0063] ​Also, here, the refrigerant return pipe 41 is connected to the heat-source-side liquid refrigerant pipe 34, and the refrigerant cooler 45 is provided. The refrigerant return pipe 41 branches a part of the refrigerant flowing in the heat-source-side liquid refrigerant pipe 34 and sends it to the compressor 21. The refrigerant cooler 45 cools the refrigerant flowing in the heat-source-side liquid refrigerant pipe 34 using the refrigerant flowing in the refrigerant return pipe 41. Here, the heat-source-side expansion valve 25 is provided in the heat-source-side liquid refrigerant pipe 34 in a portion on the heat-source-side heat exchanger 23 side than the refrigerant cooler 45.

[0064] The refrigerant return pipe 41 is a refrigerant pipe that transports the refrigerant branched from the heat-source-side liquid refrigerant pipe 34 to the suction side of the compressor 21. Also, the refrigerant return pipe 41 mainly has a refrigerant return inlet pipe 42 and a refrigerant return outlet pipe 43. The refrigerant return inlet pipe 42 branches a part of the refrigerant flowing in the heat-source-side liquid refrigerant pipe 34 from a portion between the liquid side end of the heat-source-side heat exchanger 23 and the liquid side stop valve 27 (here, a portion between the heat-source-side expansion valve 25 and the refrigerant cooler 45) and sends it to an inlet on the refrigerant return pipe 41 side of the refrigerant cooler 45. The refrigerant return expansion valve 44 is provided in the refrigerant return inlet pipe 42. The refrigerant return expansion valve 44 adjusts the flow rate of the refrigerant flowing through the refrigerant cooler 45 while decompressing the refrigerant flowing through the refrigerant return pipe 41. The refrigerant return expansion valve 44 is constituted by an electric expansion valve. The refrigerant return outlet pipe 43 sends the refrigerant from an outlet on the refrigerant return pipe 41 side of the refrigerant cooler 45 to the suction refrigerant pipe 31. The refrigerant return outlet pipe 43 of the refrigerant return pipe 41 is connected to a portion on the inlet side of the accumulator 29 in the suction refrigerant pipe 31. Also, the refrigerant cooler 45 cools the refrigerant flowing in the heat-source-side liquid refrigerant pipe 34 using the refrigerant flowing in the refrigerant return pipe 41.

[0065] Various sensors are provided in the heat-source-side unit 2. Specifically, the heat-source-side unit 2 is provided with: a discharge pressure sensor 36 that detects the pressure (discharge pressure) of the refrigerant discharged from the compressor 21; a discharge temperature sensor 37 that detects the temperature (discharge temperature) of the refrigerant discharged from the compressor 21; and a suction pressure sensor 39 that detects the pressure (suction pressure) of the refrigerant sucked into the compressor 21. Also, the heat-source-side unit 2 is provided with a heat-source-side heat exchanger liquid side sensor 38 that detects the temperature (heat-source-side heat exchanger outlet temperature) of the refrigerant at the liquid side end of the heat-source-side heat exchanger 23.

[0066] (1-4) Relay Unit

[0067] The relay units 4a, 4b, 4c, 4d are provided in a space SP1 behind the ceiling of a room SP (see FIG. 1) of a building or the like. The relay units 4a, 4b, 4c, 4d are interposed between the utilization-side units 3a, 3b, 3c, 3d and the heat-source-side unit 2 together with the liquid refrigerant communication pipe 5 and the gas refrigerant communication pipe 6, and constitute a part of the refrigerant circuit 10. The relay units 4a, 4b, 4c, 4d are sometimes arranged close to the utilization-side units 3a, 3b, 3c, 3d, sometimes arranged away from the utilization-side units 3a, 3b, 3c, 3d, and sometimes the relay units 4a, 4b, 4c, 4d are concentratedly arranged at one site. Figure 3

[0068] Next, the structure of the relay unit 4a, 4b, 4c, 4d will be described. Since the relay unit 4a has the same structure as the relay units 4b, 4c, 4d, only the structure of the relay unit 4a will be described here, and for the structures of the relay units 4b, 4c, 4d, "b", "c", or "d" will be added instead of "a" of the symbols indicating the respective parts of the relay unit 4a, and the description of the respective parts will be omitted.

[0069] The relay unit 4a mainly has a liquid connection pipe 61a and a gas connection pipe 62a.

[0070] One end of the liquid connection pipe 61a is connected to the first branch pipe portion 5a of the liquid refrigerant communication pipe 5, and the other end is connected to the second branch pipe portion 5aa of the liquid refrigerant communication pipe 5. A liquid relay expansion valve 71a is provided in the liquid connection pipe 61a. The liquid relay expansion valve 71a is an electric expansion valve.

[0071] One end of the gas connection pipe 62a is connected to the first branch pipe portion 6a of the gas refrigerant communication pipe 6, and the other end is connected to the second branch pipe portion 6aa of the gas refrigerant communication pipe 6. A gas relay expansion valve 68a is provided in the gas connection pipe 62a. The gas relay expansion valve 68a is an electric expansion valve.

[0072] Further, the liquid relay expansion valve 71a and the gas relay expansion valve 68a are set to a fully open state when the refrigeration operation or the heating operation is performed.

[0073] (1-5) Control portion

[0074] As Figure 4 ​As shown, the control section 19 is configured by the heat source side control section 92, the relay side control sections 94a, 94b, 94c, 94d, and the utilization side control sections 93a, 93b, 93c, 93d connected via the transmission lines 95, 96. The heat source side control section 92 controls the constituent devices of the heat source side unit 2. The relay side control sections 94a, 94b, 94c, 94d control the constituent devices of the relay units 4a, 4b, 4c, 4d. The utilization side control sections 93a, 93b, 93c, 93d control the constituent devices of the utilization side units 3a, 3b, 3c, 3d. The heat source side control section 92 provided in the heat source side unit 2, the relay side control sections 94a, 94b, 94c, 94d provided in the relay units 4a, 4b, 4c, 4d, and the utilization side control sections 93a, 93b, 93c, 93d provided in the utilization side units 3a, 3b, 3c, 3d can exchange information such as control signals with each other via the transmission lines 95, 96.

[0075] The heat source side control section 92 includes a control substrate on which a microcomputer, a memory, and the like are mounted, and is connected to the various constituent devices 21, 22, 24, 25, 44 of the heat source side unit 2, the various sensors 36, 37, 38, 39. The relay side control sections 94a, 94b, 94c, 94d include a control substrate on which a microcomputer, a memory, and the like are mounted, and are connected to the gas relay shutoff valves 68a to 68d and the liquid relay shutoff valves 71a to 71d of the relay units 4a, 4b, 4c, 4d. Further, the relay side control sections 94a, 94b, 94c, 94d and the heat source side control section 92 are connected via the first transmission line 95. The utilization side control sections 93a, 93b, 93c, 93d include a control substrate on which a microcomputer, a memory, and the like are mounted, and are connected to the various constituent devices 51a to 51d, 55a to 55d of the utilization side units 3a, 3b, 3c, 3d, the various sensors 57a to 57d, 58a to 58d, 59a to 59d, 79a to 79d. Here, the wiring for connecting the refrigerant leakage detection sections 79a, 79b, 79c, 79d to the utilization side control sections 93a, 93b, 93c, 93d is provided as the wiring 97a, 97b, 97c, 97d. Further, the utilization side control sections 93a, 93b, 93c, 93d and the relay side control sections 94a, 94b, 94c, 94d are connected via the second transmission line 96.

[0076] Thus, the control unit 19 performs operation control of the entire air conditioning apparatus 1. Specifically, the control unit 19 performs control of various constituent devices 21, 22, 24, 25, 44, 51a to 51d, 55a to 55d, 68a to 68d, 71a to 71d of the air conditioning apparatus 1 (here, the heat source side unit 2, the utilization side units 3a, 3b, 3c, 3d, and the relay units 4a, 4b, 4c, 4d) based on detection signals of the above-described various sensors 36, 37, 38, 39, 57a to 57d, 58a to 58d, 59a to 59d, 79a to 79d, and the like.

[0077] (2) Basic operation of air conditioning apparatus

[0078] Next, the basic operation of the air conditioning apparatus 1 will be described. As described above, the basic operation of the air conditioning apparatus 1 is the cooling operation and the heating operation. In addition, the basic operation of the air conditioning apparatus 1 described below is performed by the control unit 19 that controls the constituent devices of the air conditioning apparatus 1 (the heat source side unit 2, the utilization side units 3a, 3b, 3c, 3d, and the relay units 4a, 4b, 4c, 4d).

[0079] (2-1) Cooling operation

[0080] In the cooling operation, for example, when all of the utilization side units 3a, 3b, 3c, 3d perform the cooling operation (an operation in which the utilization side heat exchangers 52a, 52b, 52c, 52d all function as evaporators of the refrigerant, and the heat source side heat exchanger 23 functions as a heat sink of the refrigerant), the switching mechanism 22 is switched to the cooling operation state (a state shown by a solid line of the switching mechanism 22), and the compressor 21, the heat source side fan 24, and the utilization side fans 55a, 55b, 55c, 55d are driven. Also, the liquid relay shut-off valves 71a, 71b, 71c, 71d and the gas relay shut-off valves 68a, 68b, 68c, 68d of the relay units 4a, 4b, 4c, 4d are set to the fully open state. Figure 2

[0081] Here, the operation of various devices of the utilization side units 3a, 3b, 3c, 3d is performed by the utilization side control units 93a, 93b, 93c, 93d. The utilization side control units 93a, 93b, 93c, 93d transmit information indicating that the utilization side units 3a, 3b, 3c, 3d perform the cooling operation to the heat source side control unit 92 and the relay side control units 94a, 94b, 94c, 94d via the transmission lines 95, 96. The operation of various devices of the heat source side unit 2 and the relay units 4a, 4b, 4c, 4d is performed by the heat source side control unit 92 and the relay side control units 94a, 94b, 94c, 94d that receive the information from the utilization side units 3a, 3b, 3c, 3d.

[0082] ​During cooling operation, high-pressure refrigerant discharged from the compressor 21 is sent to the heat-source-side heat exchanger 23 through the switching mechanism 22. The refrigerant sent to the heat-source-side heat exchanger 23 is cooled and condensed by heat exchange with outdoor air supplied by the heat-source-side fan 24 in the heat-source-side heat exchanger 23 functioning as a heat sink for the refrigerant. The refrigerant described above flows out of the heat-source-side unit 2 through the heat-source-side expansion valve 25, the refrigerant cooler 45, and the liquid-side shutoff valve 27. At this time, the refrigerant flowing out of the heat-source-side unit 2 is cooled by the refrigerant flowing in the refrigerant return pipe 41 in the refrigerant cooler 45.

[0083] The refrigerant flowing out of the heat-source-side unit 2 is sent to the relay units 4a, 4b, 4c, 4d in branched form through the liquid refrigerant communication pipe 5 (the merging pipe portion and the first branch pipe portions 5a, 5b, 5c, 5d). The refrigerant sent to the relay units 4a, 4b, 4c, 4d flows out of the relay units 4a, 4b, 4c, 4d through the liquid relay shutoff valves 71a, 71b, 71c, 71d.

[0084] The refrigerant flowing out of the relay units 4a, 4b, 4c, 4d is sent to the utilization-side units 3a, 3b, 3c, 3d through the second branch pipe portions 5aa, 5bb, 5cc, 5dd (portions of the liquid refrigerant communication pipe 5 connecting the relay units 4a, 4b, 4c, 4d with the utilization-side units 3a, 3b, 3c, 3d). The refrigerant sent to the utilization-side units 3a, 3b, 3c, 3d is depressurized by the utilization-side expansion valves 51a, 51b, 51c, 51d and then sent to the utilization-side heat exchangers 52a, 52b, 52c, 52d. The refrigerant sent to the utilization-side heat exchangers 52a, 52b, 52c, 52d is heated and evaporated by heat exchange with indoor air supplied from the room by the utilization-side fans 55a, 55b, 55c, 55d in the utilization-side heat exchangers 52a, 52b, 52c, 52d functioning as evaporators for the refrigerant. The evaporated refrigerant flows out of the utilization-side units 3a, 3b, 3c, 3d. On the other hand, the indoor air cooled in the utilization-side heat exchangers 52a, 52b, 52c, 52d is sent to the room, whereby cooling of the room is performed.

[0085] The refrigerant flowing out of the utilization-side units 3a, 3b, 3c, 3d is sent to the relay units 4a, 4b, 4c, 4d through the second branch pipe portions 6aa, 6bb, 6cc, 6dd of the gas refrigerant communication pipe 6. The refrigerant sent to the relay units 4a, 4b, 4c, 4d flows out of the relay units 4a, 4b, 4c, 4d through the gas relay shutoff valves 68a, 68b, 68c, 68d.

[0086] The refrigerant flowing out from the relay units 4a, 4b, 4c, 4d is sent to the heat-source-side unit 2 in a confluent state through the gas refrigerant communication pipe 6 (the confluent pipe portion and the first branch pipe portions 6a, 6b, 6c, 6d). The refrigerant sent to the heat-source-side unit 2 is sucked into the compressor 21 through the gas-side shut valve 28, the switching mechanism 22, and the accumulator 29.

[0087] (2-2) Heating operation

[0088] In the heating operation, for example, when all of the utilization-side units 3a, 3b, 3c, 3d perform the heating operation (an operation in which all of the utilization-side heat exchangers 52a, 52b, 52c, 52d function as heat radiators of the refrigerant, and the heat-source-side heat exchanger 23 functions as an evaporator of the refrigerant), the switching mechanism 22 is switched to the heating operation state (a state indicated by a broken line of the switching mechanism 22), and the compressor 21, the heat-source-side fan 24, and the utilization-side fans 55a, 55b, 55c, 55d are driven. Also, the liquid relay shut valves 71a, 71b, 71c, 71d and the gas relay shut valves 68a, 68b, 68c, 68d of the relay units 4a, 4b, 4c, 4d are set to a full-open state. Figure 2

[0089] Here, the operation of various devices of the utilization-side units 3a, 3b, 3c, 3d is performed by the utilization-side control sections 93a, 93b, 93c, 93d. The utilization-side control sections 93a, 93b, 93c, 93d transmit information indicating that the utilization-side units 3a, 3b, 3c, 3d perform the heating operation to the heat-source-side control section 92 and the relay-side control sections 94a, 94b, 94c, 94d via the transmission lines 95, 96. The operation of various devices of the heat-source-side unit 2 and the relay units 4a, 4b, 4c, 4d is performed by the heat-source-side control section 92 and the relay-side control sections 94a, 94b, 94c, 94d that receive the information from the utilization-side units 3a, 3b, 3c, 3d.

[0090] The high-pressure refrigerant discharged from the compressor 21 flows out from the heat-source-side unit 2 through the switching mechanism 22 and the gas-side shut valve 28.

[0091] The refrigerant flowing out from the heat-source-side unit 2 is sent to the relay units 4a, 4b, 4c, 4d through the gas refrigerant communication pipe 6 (the confluent pipe portion and the first branch pipe portions 6a, 6b, 6c, 6d). The refrigerant sent to the relay units 4a, 4b, 4c, 4d flows out from the relay units 4a, 4b, 4c, 4d through the gas relay shut valves 68a, 68b, 68c, 68d.

[0092] ​The refrigerant flowing out from the relay units 4a, 4b, 4c, 4d is sent to the utilization-side units 3a, 3b, 3c, 3d through the second branch pipe portions 6aa, 6bb, 6cc, 6dd (the portions of the gas refrigerant communication pipe 6 connecting the relay units 4a, 4b, 4c, 4d with the utilization-side units 3a, 3b, 3c, 3d). The refrigerant sent to the utilization-side units 3a, 3b, 3c, 3d is sent to the utilization-side heat exchangers 52a, 52b, 52c, 52d. The high-pressure refrigerant sent to the utilization-side heat exchangers 52a, 52b, 52c, 52d is cooled and condensed in the utilization-side heat exchangers 52a, 52b, 52c, 52d functioning as a heat radiator of the refrigerant, by heat exchange with the indoor air supplied from the indoor by the utilization-side fans 55b, 55c, 55d. The condensed refrigerant flows out from the utilization-side units 3a, 3b, 3c, 3d after being depressurized by the utilization-side expansion valves 51a, 51b, 51c, 51d. On the other hand, the indoor air heated in the utilization-side heat exchangers 52a, 52b, 52c, 52d is sent to the indoor, whereby heating of the indoor is performed.

[0093] The refrigerant flowing out from the utilization-side units 3a, 3b, 3c, 3d is sent to the relay units 4a, 4b, 4c, 4d via the second branch pipe portions 5aa, 5bb, 5cc, 5dd (the portions of the liquid refrigerant communication pipe 5 connecting the relay units 4a, 4b, 4c, 4d with the utilization-side units 3a, 3b, 3c, 3d). The refrigerant sent to the relay units 4a, 4b, 4c, 4d flows out from the relay units 4a, 4b, 4c, 4d through the liquid relay shutoff valves 71a, 71b, 71c, 71d.

[0094] The refrigerant flowing out from the relay units 4a, 4b, 4c, 4d is sent to the heat-source-side unit 2 in a combined state through the liquid refrigerant communication pipe 5 (the merging pipe portion and the first branch pipe portions 5a, 5b, 5c, 5d). The refrigerant sent to the heat-source-side unit 2 is sent to the heat-source-side expansion valve 25 through the liquid-side shutoff valve 27 and the refrigerant cooler 45. The refrigerant sent to the heat-source-side expansion valve 25 is depressurized by the heat-source-side expansion valve 25, and is sent to the heat-source-side heat exchanger 23. The refrigerant sent to the heat-source-side heat exchanger 23 is heated and evaporated by heat exchange with the outdoor air supplied by the heat-source-side fan 24. The evaporated refrigerant is sucked into the compressor 21 through the switching mechanism 22 and the accumulator 29.

[0095] (3) Operation of the air-conditioning apparatus when refrigerant leaks

[0096] Next, the use of the air-conditioning apparatus will be described. Figure 5The illustrated control flow explains the operation of the air conditioning device 1 when a refrigerant leaks. Also, the operation of the air conditioning device 1 when a refrigerant leaks explained below is performed by the control section 19 controlling the constituent devices of the air conditioning device 1 (the heat source side unit 2, the utilization side units 3a, 3b, 3c, 3d, and the relay units 4a, 4b, 4c, 4d) as with the basic operation described above.

[0097] The same control is applied to any of the utilization side units 3a, 3b, 3c, 3d when a refrigerant leaks, and thus, here, the case where a refrigerant is detected to leak to the room in which the utilization side unit 3a is provided is explained as an example.

[0098] In Figure 5 In step S1, it is determined whether or not any of the refrigerant leak detectors 79a, 79b, 79c, 79d of the utilization side units 3a, 3b, 3c, 3d has detected a refrigerant leak. Here, in the case where the refrigerant leak detector 79a of the utilization side unit 3a has detected a refrigerant leak to the installation space (room) of the utilization side unit 3a, the processing proceeds to the next step S2.

[0099] In step S2, in the utilization side unit 3a in which a refrigerant leak has occurred, an alarm (not shown) that emits a warning sound such as a buzzer and lights a lamp is activated to alert a person in the installation space of the utilization side unit 3a.

[0100] Next, in step S3, it is determined whether or not the utilization side unit 3a is performing a cooling operation. Here, in the case where the utilization side unit 3a is performing a cooling operation, or when the utilization side unit 3a is in a stopped or temporarily stopped state in which neither cooling nor heating is performed, the processing proceeds from step S3 to step S4.

[0101] In step S4, the utilization side unit 3a is caused to perform a cooling operation to lower the pressure of the refrigerant of the utilization side unit 3a. However, the cooling operation in this step S4 is different from the usual cooling operation, and is an operation that preferentially lowers the pressure of the refrigerant of the utilization side unit 3a. When the air conditioning device 1 is performing a heating operation, the state of the switching mechanism 22 is switched to a cooling operation state, and the air conditioning device 1 is caused to perform a cooling operation. When the utilization side unit 3a is in a stopped or temporarily stopped state, the utilization side unit 3a is set to a cooling operation state, and the pressure of the refrigerant of the utilization side unit 3a is lowered.

[0102] Immediately after the step S4, the opening degree of the heat source side expansion valve 25 of the heat source side unit 2 is reduced in the step S5. In the normal cooling operation, the heat source side expansion valve 25 is fully opened, and the opening degree of the heat source side expansion valve 25 is reduced here, so that the pressure of the refrigerant flowing to the utilization side units 3a, 3b, 3c, 3d is reduced. In addition, the utilization side expansion valve 51a of the utilization side unit 3a is set to the fully open state.

[0103] Further, in the step S5, the opening degree of the refrigerant return expansion valve 44 is made larger than in the normal cooling operation, so that the amount of the refrigerant flowing through the refrigerant return pipe 41 functioning as a bypass passage is increased. Thus, of the refrigerant that has performed heat release, condensed in the heat source side heat exchanger 23, and is heading toward the utilization side units 3a, 3b, 3c, 3d, more refrigerant returns to the suction side of the compressor 21 through the refrigerant return pipe 41. In other words, the amount of the refrigerant that has performed heat release, condensed in the heat source side heat exchanger 23, and is heading toward the utilization side units 3a, 3b, 3c, 3d is reduced. By the above control, the pressure of the refrigerant of the utilization side unit 3a, in which the refrigerant has leaked, is reduced more quickly. Further, the refrigerant flowing through the refrigerant return pipe 41 flows into the accumulator 29. Thus, a part of the refrigerant flowing in can be stored in the accumulator 29.

[0104] Further, in the step S5, the rotation speed of the utilization side fan 55a is also reduced.

[0105] In the step S6, whether the pressure of the refrigerant of the utilization side unit 3a is sufficiently low is determined on the basis of the sensor values of the utilization side heat liquid side sensor 57a and the utilization side heat gas side sensor 58a of the utilization side unit 3a. When it is determined that the sensor values satisfy a prescribed condition, and the pressure of the refrigerant of the utilization side unit 3a is sufficiently low, the process shifts from the step S6 to the step S7. Further, in the step S6, the elapsed time is also monitored, and if a prescribed time elapses after the step S5 is executed, it is determined that the pressure of the refrigerant of the utilization side unit 3a is reduced to some extent, and the process shifts to the step S7.

[0106] Further, in the step S6, the pressure of the refrigerant of the utilization side unit 3a is monitored, and the control is performed in such a manner that the pressure of the refrigerant in the utilization side unit 3a is not less than the atmospheric pressure in substance. The process shifts from the step S6 to the step S7 before the pressure of the refrigerant in the utilization side unit 3a becomes less than the atmospheric pressure.

[0107] In step S7, the liquid relay shut-off valve 71a and the gas relay shut-off valve 68a of the relay unit 4a corresponding to the refrigerant-leaking unit 3a where the refrigerant leak has occurred are closed. This disconnects the refrigerant circuit 10 from which the refrigerant circulates in the utilization unit 3a, resulting in almost no refrigerant inflow from the heat source unit 2 to the utilization unit 3a. Then, in step S7, the operation of all units, including the other utilization units 3b, 3c, 3d and the heat source unit 2, is stopped.

[0108] (4) Selection of liquid relay shut-off valve and gas relay shut-off valve

[0109] As described above, liquid relay shut-off valves 71a, 71b, 71c, 71d and gas relay shut-off valves 68a, 68b, 68c, 68d are controlled to close when a refrigerant leak is detected (see [link]). Figure 4 Step S7). In other words, when a refrigerant leak is detected in any of the utilizing side units 3a, 3b, 3c, and 3d, the liquid relay shut-off valves 71a, 71b, 71c, and 71d and the gas relay shut-off valves 68a, 68b, 68c, and 68d of the corresponding relay units 4a, 4b, 4c, and 4d switch from the open, non-shutdown state to the closed, shut-off state.

[0110] In the air conditioning unit 1 of this embodiment, the liquid relay shut-off valves 71a, 71b, 71c, 71d and the gas relay shut-off valves 68a, 68b, 68c, 68d are selected in the following manner. The selection method for any of the liquid relay shut-off valves 71a, 71b, 71c, 71d and the gas relay shut-off valves 68a, 68b, 68c, 68d is the same; therefore, they will be simply referred to as shut-off valves in the following description.

[0111] (4-1) Regarding rooms in side units equipped with air conditioning

[0112] First, before selecting the shut-off valve, information about the building equipped with air conditioning unit 1 is obtained, specifically information about the rooms with side units 3a, 3b, 3c, and 3d.

[0113] Here, four units are configured together using side units 3a, 3b, 3c, and 3d and relay units 4a, 4b, 4c, and 4d. Figure 3 The ceiling-back space SP1 of the room (defined space) SP shown. Side units are not installed on the floor FL of this room SP. In other words, side units 3a, 3b, 3c, and 3d are ceiling-mounted units, not floor-mounted units.

[0114] The room SP is provided with a door DR for people to enter and exit. The door DR is closed when people are not entering and exiting. There is a gap (undercut) UC below the door DR. Also, a ventilation port, not shown, is provided in the ceiling of the room SP. The area of the gap UC is A d (m 2 ). For example, if the height dimension of the gap UC is 4 mm and the width dimension is 800 mm, the area A d of the gap UC is their product, 0.0032 (m 2 ).

[0115] Also, the utilization-side units 3a, 3b, 3c, 3d are arranged in the ceiling back space SP1 of the room SP, so the distance H from the floor FL to the utilization-side circuit 3aa, 3bb, 3cc, 3dd of the utilization-side unit 3a, 3b, 3c, 3d is equal to the height dimension (ceiling height) of the room SP.

[0116] (4-2) Maximum allowable air leakage amount allowed during the shutoff state of the shutoff valve (leakage amount during shutoff)

[0117] Next, the calculation method of the leakage amount during shutoff required for selection of the liquid relay shutoff valve and the gas relay shutoff valve will be explained. In the following explanation, general shutoff valves, shutoff valves specific to the utilization-side unit of the air conditioning device 1 of the present embodiment, and the utilization-side unit will be described without designating symbols, so the explanation will be made without designating symbols.

[0118] (4-2-1)

[0119] As explained in the above "SUMMARY", in the guideline "Appendix A (Regulation) Specifications of Safety Shutoff Valves" of the Japan Refrigeration and Air-Conditioning Industry Association, 300 (cm 3 / min) or less is specified as the leakage amount during shutoff that a safety shutoff valve should satisfy when the fluid is air and the pressure difference before and after the safety shutoff valve is 1 MPa. First, the valve gap during shutoff is found according to this condition.

[0120] The valve gap cross-sectional area Av is found according to the air volume flow rate, the inlet absolute pressure of air, the density of air, and the specific heat ratio of air, and the equivalent diameter d v of the valve gap is found assuming the cross section to be circular. The specific heat ratio K of air is set to 1.40 (20°C). When the pressure ratio P2 / P1 exceeds (2 / (K+1))x(K / (K-1)), the flow rate exceeds the sonic speed. In the above pressure difference,

[0121] P2 / P1 = (1+0.1013) / 0.1013 = 10.87

[0122] (2 / (k+1)) x (k / (k-1)) = (2 / 2.4) x 1.4 / 0.4 = 0.528

[0123] Therefore, the flow rate exceeds the supersonic speed.

[0124] Mass flow rate G a , volume flow rate Q a , valve gap equivalent diameter d v is found by the following equation. In the case where the flow rate exceeds the sonic speed,

[0125] (Formula 1):

[0126] G a = A v x (2 / (k+1)) ((κ+1) / 2(κ－1)) x (k x P 1a x p 1a ) 0.5

[0127] (Formula 2):

[0128] A v = Q a x p 2a x (2 / (k+1)) (－(κ+1) / 2(κ－1)) x (k x P 1a x p 1a ) (－0.5)

[0129] (Formula 3):

[0130] d v = (4 x A v / π) 0.5

[0131] In the above "Appendix A (Regulation) of the specifications of safety shutoff valves", the allowable leakage amount at the time of closing (leakage amount at the time of closing) to be satisfied is regulated to be 300 (cm 3 / min) or less, which corresponds to 5 x 10 -6 (m 3 / s). Also, in the guideline, the same allowable leakage amount at the time of closing is regulated for the shutoff valves of the liquid refrigerant communication pipe and the gas refrigerant communication pipe, so that the same valve gap is assumed for the shutoff valves of both.

[0132] This condition is substituted into (Formula 2) and A v is found. The allowable valve gap (d vG ) and the valve gap cross-sectional area (A vG ) in the above "Appendix A (Regulation) of the specifications of safety shutoff valves" are:

[0133] d vG = d vL= 5.47E-5 (m)

[0134] A vG = A vL = 2.24E-9 (m 2 ).

[0135] (4-2-2)

[0136] Next, the leakage speed G vG of the refrigerant leaked from the calculated valve gap (d r ) is calculated.

[0137] The calculation is performed assuming the following case: in the liquid side pipe (liquid refrigerant communication pipe), the upstream side of the shutoff valve from the utilization side unit is the refrigerant in the liquid phase, and in the gas side pipe (gas refrigerant communication pipe), the upstream side of the shutoff valve from the utilization side unit is the refrigerant in the gas phase.

[0138] First, assuming that the leakage hole is an orifice and the refrigerant in the liquid phase passes through the leakage hole, when the leakage speed (G rL ) of the refrigerant in the liquid side pipe is calculated according to Bernoulli's theorem,

[0139] (Formula 4):

[0140] G rL = C r × (2 x ΔP r / p 1rl ) 0.5 x A vL x p 1rl .

[0141] Next, the leakage speed (G rG ) of the refrigerant in the gas side pipe exceeds the speed of sound. The specific heat ratio K takes the value of the 20°C saturated gas of the refrigerant as a representative value. Thus, the leakage speed (G rG ) of the refrigerant in the gas side pipe is

[0142] (Formula 5):

[0143] G rG = A vG x (2 / (λ + 1)) ((λ+1) / 2(λ－1)) x (λ x P 1r x p 1rg ) 0.5 .

[0144] Therefore, the leakage speed G r of the refrigerant to the room SP when the shutoff valve is closed in both the liquid side pipe and the gas side pipe is

[0145] (Formula 6):

[0146] G r = G rL + G rG

[0147] = C r × (2 × ΔP r / ρ 1rl ) 0.5 × A vL × ρ 1rl + A vG × (2 / (λ + 1)) ((λ+1) / 2(λ－1)) × (λ × P 1r × ρ 1rg ) 0.5

[0148] In addition, as variables that affect the leakage speed of refrigerant leaking from the valve gap of the shutoff valve, (4-2-2-A) to (4-2-2-E) can be cited. The respective calculation methods are shown below.

[0149] (4-2-2-A) Type of refrigerant

[0150] Assuming any one of R32, R452B, R454B, R1234yf, and R1234ze(E) as the refrigerant, the physical property values of each refrigerant were calculated using NIST Refprop V9.1.

[0151] (4-2-2-B) Ambient temperature at which the refrigerant pressure on the upstream side of the shutoff valve after the air conditioning apparatus is stopped and the pressure difference between the refrigerant pressure and the atmospheric pressure are determined

[0152] It can be considered that the pressure of the refrigerant located at the unit side (upstream side) of the shutoff valve on the heat source side after the air conditioning apparatus is stopped is determined by the maximum temperature outside the building. According to the high temperature test conditions for air conditioning apparatuses in the United States (Table 1 below), the maximum temperature outside is set to 55°C, and the refrigerant pressure on the upstream side of the shutoff valve is set to the saturation pressure at 55°C.

[0153] [Table 1]

[0154]

[0155] a The outdoor relative humidity is not specified because it has no effect on performance.

[0156] b Dew point temperature and relative humidity evaluated at 0.973 atm (14.3 psi)

[0157] c According to AHRI standards 210 / 240

[0158] ​d T3* is a modified T3 condition in which the indoor setup is similar to the AHRI condition.

[0159] Source:

[0160] Alternative Refrigerant Evaluation for High-Ambient-Temperature Environments: R-22 and R-410A Alternatives for Mini-Split Air Conditioners, ORNL, P5, 2015

[0161] (4-2-2-C) Liquid density, gas density

[0162] The mass concentration of refrigerant in the liquid phase (kg / m3) is calculated using NIST Refprop V9.1. 3 ) and the mass concentration of refrigerant in the gas phase (kg / m3) is calculated using NIST Refprop V9.1. 3

[0163] (4-2-2-D) Ratio of specific heat

[0164] The ratio of specific heat is calculated using NIST Refprop V9.1. In addition, the ratio of specific heat of saturated gas of refrigerant at 27°C is used.

[0165] (4-2-2-E) State of refrigerant in liquid-side pipe and gas-side pipe

[0166] After the shutoff valve is made into a shutoff state, the refrigerant in the liquid-side pipe and the refrigerant in the gas-side pipe on the upstream side of the shutoff valve are assumed to be in a liquid phase and a gas phase, or in a gas phase and a gas phase. Here, calculation is performed assuming the former in which the amount of leakage of refrigerant is calculated to be larger. In other words, calculation is performed assuming that, after the shutoff valve is made into a shutoff state, the refrigerant in the liquid-side pipe on the upstream side of the shutoff valve is in a liquid phase and the refrigerant in the gas-side pipe on the upstream side of the shutoff valve is in a gas phase.

[0167] If the variables are calculated as described above, the leakage speed of refrigerant leaked from the valve gap is, for example, as shown in Table 2 below for different refrigerants.

[0168] [Table 2]

[0169] Leakage speed of refrigerant passing through the valve gap when the shutoff valve is closed

[0170] ​

[0171] (Conditions) Ambient temperature 55°C, shut-off valve gap equivalent to 300 cc / min, specific heat ratio 27°C.

[0172] Furthermore, by simply changing the physical property values, the leakage rates for different ambient temperatures (external building temperatures) can be calculated using equations (4), (5), and (6) above. There is a tendency for higher ambient temperatures to result in higher leakage rates. Therefore, by determining the leakage rates under the external temperatures (highest external gas temperatures) of each region, it is possible to select and design shut-off valves suitable for each region.

[0173] (4-2-3)

[0174] Next, calculate the refrigerant discharge rate G of the refrigerant discharged from the gap UC below the door DR to the outside of the room. d .

[0175] (Equation 7): G d =ρ md ×V md ×A d

[0176] (Equation 8): V md =C d ×(2×Δp d / ρ md ) 0.5

[0177] (Equation 9): Δp d =(ρ md -ρ a )×g×h s

[0178] (Equation 10): ρ md =ρ mr +ρ ma

[0179] (Equation 11): ρ mr =N / 100×(U r ×10 -3 ) / (24.5×10 -3 )

[0180] (Equation 12): ρ ma = (100-N) / 100×(U) a ×10 -3 ) / (24.5×10 -3 )

[0181] (Formula 13): N=LFL / S

[0182] As variables that affect the refrigerant discharge speed, (4-2-3-A) and (4-2-3-B) can be cited.

[0183] (4-2-3-A) Leakage height

[0184] (4-2-3-B) Safety factor of average refrigerant concentration in the room with respect to LFL

[0185] The leakage height is, for example, 2.2 m in the case where the utilization-side unit is provided at the ceiling, and 0.6 m in the case where the utilization-side unit is provided on the floor (refer to IEC 60335-2-40:2016). Also, the allowable average concentration is formed by dividing the LFL by the safety factor, and the refrigerant discharge speed is affected, for example, as shown in Table 3 below, in terms of whether the safety factor is set to 4 or 2.

[0186] [Table 3]

[0187] Refrigerant discharge speed G that is discharged toward the outside of the room through the door lower gap d [kg / h]

[0188]

[0189] (4-2-4)

[0190] Next, the maximum allowable air leakage amount (Q max ) in the shutoff state of the shutoff valve when the gap UC is present below the door DR is calculated.

[0191] As long as the refrigerant discharge speed G d that is discharged toward the room SP outside through the gap UC is greater than the refrigerant leakage speed G r when the shutoff valve is in the shutoff state, the allowable air leakage amount can be made greater than 300 (cm 3 / min). As described in (4-2-1) above, if the same maximum allowable air leakage amount (Q max ) is specified for the shutoff valves of the liquid-side line and the gas-side line, the ratio R with respect to 300 (cm 3 / min) specified by the guideline of the Japan Refrigeration and Air-Conditioning Industry Association is the same in each of the shutoff valves of the liquid-side line and the gas-side line.

[0192] (Formula 14):

[0193] R = G d / G r

[0194] (Formula 15):

[0195] Q max = 300 x R

[0196] Here, it is considered that liquid-phase refrigerant exists upstream of the shutoff valve of the liquid-side line and gas-phase refrigerant exists upstream of the shutoff valve of the gas-side line before the shutoff valve becomes the shutoff state. If (Formula 6) and (Formula 8) are substituted into (Formula 15), the following (Formula 16) is formed.

[0197] (Formula 16):

[0198] R = (p md × V md × A d ) / (C r × (2 × ΔP r / p 1r ) 0.5 × A v × p 1rl + A v × (2 / (λ + 1)) ((λ+1) / 2(λ－1)) × (λ × P 1r × p 1rg ) 0.5 )

[0199] If the allowable multiple R related to each refrigerant is found using this (Formula 16), it is shown in Table 4 below, for example.

[0200] [Table 4]

[0201] Maximum allowable air leakage amount Q v of the allowable multiple R

[0202]

[0203] (4-2-5)

[0204] Next, based on the results of investigating actual refrigerant leakage cases occurring on the market, a refrigerant leakage hole opened on the heat source side circuit of the utilization side unit was examined.

[0205] Cases of opening of holes and refrigerant leakage due to corrosion and the like of a part of the utilization side circuit of the utilization side unit of an air conditioning device have been reported. According to the “Risk Evaluation Report on Multi-Connected Air Conditioners for Buildings Using Micro-Flammable Refrigerants” (issued on September 20, 2017) of the Japan Refrigeration and Air-Conditioning Industry Association, utilization side units in which refrigerant leakage actually occurred on the market were collected and investigated for the leakage hole diameter, and as a result, the maximum leakage hole diameter was 0.174 mm. This value is 3.18 times the valve gap equivalent diameter d v = 5.47E-2 (mm) when the shutoff valve is in the shutoff state. If converted to the cross-sectional area, it is 10.1 times. Therefore, the maximum allowable air leakage amount Q maxWhen the valve gap of the shutoff valve is larger than the leak hole diameter of the utilization-side unit at the time of shutoff, the meaning of providing the shutoff valve is lost. Therefore, it is appropriate to adopt the method of stopping the above-mentioned allowable multiple R at 10.1 times.

[0206] (4-2-6)

[0207] The above, the calculation related to the leakage amount at the time of shutoff, and regarding the symbols used in each formula, etc., the symbols, etc. include the following (4-2-6-1) ~ (4-2-6-3) in the case where there is no particular limitation.

[0208] (4-2-6-1) Symbols

[0209] A: Area (unit is m 2 )

[0210] C: Flow coefficient

[0211] d: Equivalent diameter (unit is m)

[0212] G: Mass flow velocity (unit is kg·s -1 )

[0213] g: Acceleration of gravity (unit is m·s -2 )

[0214] h: Leakage height (unit is m)

[0215] L: Lower flammable limit LFL of refrigerant (unit is kg·m -3 )

[0216] N: Volume concentration of refrigerant (unit is vol%)

[0217] P: Pressure (unit is Pa)

[0218] Q: Volume flow velocity (unit is m 3 ·s -1 )

[0219] R: Valve leakage amount allowable multiple

[0220] ΔP: Pressure difference (unit is Pa)

[0221] S: Safety factor

[0222] U: Molecular weight of refrigerant

[0223] v: Velocity (unit is m·s -1 )

[0224] (4-2-6-2) Greek letters

[0225] κ: Air specific heat ratio

[0226] λ: specific heat ratio of refrigerant

[0227] p: mass concentration (unit is kg m -3 )

[0228] (4-2-6-3) subscript

[0229] a : air

[0230] d : gap under door

[0231] g : gas phase

[0232] l : liquid phase

[0233] m : mixture of refrigerant and air

[0234] r : refrigerant

[0235] s : refrigerant leakage point

[0236] v : shutoff valve

[0237] G : gas side line

[0238] L : liquid side line

[0239] 1: upstream

[0240] 2: downstream

[0241] max : allow

[0242] (5) Features of air conditioning device

[0243] (5-1)

[0244] In the air conditioning device 1, the maximum allowable air leakage amount (leakage amount at shutoff) required for the shutoff valve is calculated using the method described in (4-2) above in conjunction with conditions such as the size of the room SP in which the utilization side units 3a, 3b, 3c, 3d are installed (the size of the gap UC under the door DR, the ceiling height), the type of refrigerant (R32), the installation site of the utilization side units 3a, 3b, 3c, 3d (not floor type but ceiling installation type), and the like, and the specifications of the liquid relay shutoff valves 71a, 71b, 71c, 71d and the gas relay shutoff valves 68a, 68b, 68c, 68d are determined. Specifically, the maximum allowable air leakage amount (leakage amount at shutoff) is calculated to be 300 (cm 3the reference value of the leakage amount at the time of the cut-off, how much the allowable amount is increased is calculated as a ratio R with respect to 300 (cm 3 / min). Also, the value of the specific ratio R as in Table 4 above is found. Here, in the case where R32 is used as the refrigerant and the utilization-side units 3a, 3b, 3c, 3d are provided on the ceiling of the room SP, if the safety factor S is set to 4, then the ratio R = 1.96 as shown in Table 4.

[0245] Concomitantly therewith, in the air conditioning device 1, the specifications of the liquid relay cut-off valves 71a, 71b, 71c, 71d and the gas relay cut-off valves 68a, 68b, 68c, 68d are determined in a form such that the maximum allowable air leakage amount (leakage amount at the time of the cut-off) becomes 300 x 1.96 (cm 3 / min) or less. By this, compared to the case where the specifications are determined based on the reference value 300 (cm 3 / min), the manufacturing cost or the purchase cost of the liquid relay cut-off valves 71a, 71b, 71c, 71d and the gas relay cut-off valves 68a, 68b, 68c, 68d is reduced, and the introduction cost of the air conditioning device 1 that uses the refrigerant (R32) that prevents global warming is also suppressed.

[0246] Also, in the air conditioning device 1 where the specifications of the liquid relay cut-off valves 71a, 71b, 71c, 71d and the gas relay cut-off valves 68a, 68b, 68c, 68d have been determined as such, after the air conditioning device 1 is stopped at the step S7 based on the above Figure 5 , the amount of the refrigerant that leaks from the valve gaps of the liquid relay cut-off valves 71a and the gas relay cut-off valves 68a and flows out to the room SP is also suppressed, and the refrigerant concentration in the room SP is suppressed to a value that is sufficiently low compared to the LFL.

[0247] (5-2)

[0248] As described in (4-2-5) above, if the maximum allowable air leakage amount (leakage amount at the time of the cut-off) of the liquid relay cut-off valves 71a, 71b, 71c, 71d and the gas relay cut-off valves 68a, 68b, 68c, 68d becomes excessively large, then the meaning of the cut-off is lost.

[0249] Therefore, in view of the results of the market survey, in the air conditioning device 1, the upper limit value of the maximum allowable air leakage amount (leakage amount at the time of the cut-off) of the liquid relay cut-off valves 71a, 71b, 71c, 71d and the gas relay cut-off valves 68a, 68b, 68c, 68d is set to 300 x 10.1 = 3030 (cm 3 / min).

[0250] (6) Modified Example

[0251] (6-1)

[0252] The air conditioning apparatus 1 of the above-described embodiment is provided in a room of a building or the like, and in the case of being provided in an internal space of another building, the selection of the specification of the shutoff valve can also be changed to conform to the conditions of the target space. For example, the selection of the shutoff valve can be appropriately made for various spaces such as an internal space of a factory, a kitchen, a data center, a computer room, an internal space of a commercial facility, and the like.

[0253] (6-2)

[0254] In the above-described embodiment, as the refrigerant circulating in the refrigerant circuit 10 of the air conditioning apparatus 1, R32 is exemplified, and in the case of using other microflammable refrigerants such as R1234yf, R1234ze(E), R452B, the ratio R is calculated according to the difference in the molecular weight, LFL, and the like of the refrigerant as described above, and the specification of the shutoff valve conforming thereto is selected.

[0255] (6-3)

[0256] In the above-described embodiment, as an example of the operation of the air conditioning apparatus 1 at the time of refrigerant leakage, the control flow shown in FIG. 12 is shown, but other operations can also be performed as the operation at the time of refrigerant leakage. For example, upon detection of refrigerant leakage, the following control can be performed: the evacuation operation is performed, and then the shutoff valve is closed. Figure 5

[0257] (6-4)

[0258] In the above-described embodiment, in steps S4 and S5, the refrigeration operation by the utilization-side units 3a, 3b, 3c, 3d is performed, the opening degree of the heat-source-side expansion valve 25 is reduced, and the pressure of the refrigerant flowing to the utilization-side units 3a, 3b, 3c, 3d is lowered. However, this control is one example, and other controls can also be performed.

[0259] For example, in the case where refrigerant leakage to the installation space of the utilization-side unit 3a is detected, only the liquid relay shutoff valve 71a and the gas relay shutoff valve 68a of the relay unit 4a corresponding to this utilization-side unit 3a can be immediately closed.

[0260] Further, the following control can also be employed: in the case where refrigerant leakage to the installation space of the utilization-side unit 3a is detected, all of the liquid relay shutoff valves 71a, 71b, 71c, 71d and the gas relay shutoff valves 68a, 68b, 68c, 68d are closed in a manner such that all of the utilization-side units 3a, 3b, 3c, 3d are disconnected from the heat-source-side unit 2, and the compressor 21 of the heat-source-side unit 2 is also stopped.

[0261] (6-5)​

[0262] In the above-described embodiments, as examples of the utilization-side units, the utilization-side units 3a, 3b, 3c, 3d provided in the form of being buried in a ceiling are cited, but even if the utilization-side units of other forms are used, the selection method of the shutoff valve is the same. For example, a ceiling-suspended utilization-side unit, a floor-standing utilization-side unit, and a wall-mounted utilization-side unit fixed to a side wall can also obtain the multiplication factor R by the above-described (Formula 16).

[0263] The embodiments of the present disclosure have been described above, but it should be understood that various modifications in form and details can be made without departing from the spirit and scope of the present disclosure as recited in the claims.

[0264] Symbol explanation

[0265] 1 Air conditioning device (refrigerant circulation device);

[0266] 2 Heat-source-side unit;

[0267] 3a, 3b, 3c, 3d Utilization-side unit;

[0268] 3aa, 3bb, 3cc, 3dd Utilization-side circuit;

[0269] 5 Liquid refrigerant communication pipe;

[0270] 6 Gaseous refrigerant communication pipe;

[0271] 10 Refrigerant circuit;

[0272] 19 Control unit;

[0273] 68a, 68b, 68c, 68d Gaseous relay shutoff valve (second shutoff valve);

[0274] 71a, 71b, 71c, 71d Liquid relay shutoff valve (first shutoff valve);

[0275] 79a, 79b, 79c, 79d Refrigerant leakage detection unit (detection unit);

[0276] 222 Heat-source-side circuit.

[0277] Prior art document

[0278] Patent document

[0279] Non-patent document 1: Guidelines for Safety Assurance Facilities at the Time of Refrigerant Leakage for Commercial Air Conditioners Using Micro-flammability (A2L) Refrigerants (JRA GL-16:2017; Japan Refrigeration and Air-Conditioning Industry Association); and Appendix A (Provisions) Specifications for Safety Shutoff Valves.

Claims

1. A refrigerant circulation device (1) that circulates a slightly flammable refrigerant in a refrigerant circuit (10), the slightly flammable refrigerant being classified as slightly flammable (A2L) in ISO 817, characterized in that, include: The first shut-off valve (71a, 71b, 71c, 71d) and the second shut-off valve (68a, 68b, 68c, 68d) are disposed on both sides of the first part (3aa, 3bb, 3cc, 3dd) of the refrigerant circuit. Detection units (79a, 79b, 79c, 79d) detect leakage of refrigerant from the first portion of the refrigerant circuit to a designated space (SP); and When the detection unit detects refrigerant leakage into the designated space, the control unit (19) sets the first shut-off valve and the second shut-off valve to a shut-off state to suppress refrigerant leakage into the designated space. The leakage rates of the first and second shut-off valves under the shut-off state, where the fluid is air at 20°C and the pressure difference across them is 1 MPa, are respectively greater than 300 (cm³). 3 / min), Less than 300×R (cm) 3 / min), in, R=(ρ md ×V md ×A d ) / (C r ×(2×ΔP r / r 1rl ) 0.5 ×A v ×r 1rl +A v ×(2 / (λ+1)) ((λ+1) / 2(λ-1)) ×(λ×P 1r ×r 1rg ) 0.5 ), A v It is the valve gap cross-sectional area (m²) of the first and second shut-off valves under the shut-off state respectively. 2 ), ρ 1rl It is the mass concentration of the refrigerant in the liquid phase (kg / m³) 3 ), ρ 1rg It is the mass concentration of the refrigerant in the gas phase (kg / m³). 3 ), P 1r It refers to the refrigerant pressure (MPa) upstream of both the first and second shut-off valves, which is the refrigerant saturation pressure when the maximum external temperature of the building is set at 55°C. λ is the specific heat ratio of the refrigerant. ρ md This refers to the mass concentration (kg / m³) of the air and refrigerant mixture when the refrigerant concentration reaches the permissible average concentration of the refrigerant in the specified space after leakage into the specified space, flowing through the gap of the door separating the inside and outside of the specified space. 3 ), V md It is the velocity (m / s) of the air and refrigerant mixture as it flows through the gap of the door separating the inside and outside of the specified space, after the refrigerant has leaked into the specified space and reached the permissible average concentration of refrigerant in the specified space. A d It is the area (m²) of the gap between the doors that separate the inside and outside of the specified space. 2 ), ΔP r It is the pressure difference (Pa) between the inside and outside of the hole at the location of refrigerant leakage. It is the pressure difference between the saturation pressure of the refrigerant and atmospheric pressure when the maximum external temperature of the building is set at 55°C. C r It is the refrigerant flow coefficient when liquid refrigerant flows through the orifice at the location where refrigerant is leaking, and it is 0.

6.

2. The refrigerant circulation device (1) as described in claim 1, characterized in that, The R is 1 <R<10.1。 3. The refrigerant circulation device (1) as described in claim 1 or 2, characterized in that, The refrigerant circuit (10) includes the utilization side circuits (3aa, 3bb, 3cc, 3dd) of the utilization side units (3a, 3b, 3c, 3d), the heat source side circuit (222) of the heat source side unit (2), a liquid refrigerant connecting pipe (5), and a gaseous refrigerant connecting pipe (6). The utilization side units are located in or connected to the designated space (SP). The liquid refrigerant connecting pipe and the gaseous refrigerant connecting pipe connect the utilization side circuit and the heat source side circuit. The first part of the refrigerant circuit is the utilization side circuit. The first shut-off valves (71a, 71b, 71c, 71d) are installed in the liquid refrigerant connecting pipe. The second shut-off valve (68a, 68b, 68c, 68d) is installed in the gas refrigerant connecting pipe.

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