Refrigeration cycle device

Abstract

This refrigeration cycle device (100) comprises a main circuit (MC), an injection circuit (IC), an internal heat exchanger (10), and a degassing circuit (GC). The main circuit (MC) has a compressor (1), a condenser (2), a first receiver (5a) and a second receiver (5b), an expansion valve (3), and an evaporator (4). The degassing circuit (GC) is connected to the first receiver (5a) and the second receiver (5b) and to the injection circuit (IC), which is between an injection expansion valve (7) and the internal heat exchanger (10). A refrigerant is a supercritical refrigerant. The degassing circuit (GC) has a degassing pipe (GP) and a degassing valve (8) connected to the degassing pipe (GP). The degassing valve (8) is configured to be capable of opening and closing the degassing circuit (GC).

Description

Refrigeration Cycle Equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] In order to realize stable operation of the refrigeration cycle device regardless of uneven distribution of refrigerant in the refrigeration cycle device, a receiver is connected to the liquid pipe of the refrigeration cycle device. ２ When a supercritical refrigerant such as a refrigerant gas is stored in a receiver in a liquid state below its critical pressure, the receiver is connected to an intermediate pressure section of a refrigeration cycle device. In this case, the receiver is vented to control the pressure inside the receiver.

[0003] For example, in a refrigeration cycle device described in Japanese Patent Laid-Open No. 2022-177312 (Patent Document 1), a receiver is connected to a liquid pipe portion of the refrigeration cycle device. Carbon dioxide, which is a supercritical refrigerant, is stored in the receiver in a liquid state. A gas vent passage is connected to the receiver.

[0004] Japanese Patent Application Laid-Open No. 2022-177312

[0005] The refrigeration cycle device described in the above publication has only one receiver. Therefore, if the volume of the receiver is limited by the specifications of the high-pressure vessel, the receiver cannot store a sufficient amount of supercritical refrigerant.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and its purpose is to provide a refrigeration cycle device that can store a sufficient amount of supercritical refrigerant even if the volume of the receiver is limited, and can control the receiver pressure by venting.

[0007] The refrigeration cycle apparatus of the present disclosure includes a main circuit, an injection circuit, an internal heat exchanger, and a degassing circuit. The main circuit includes a compressor that compresses a refrigerant, a condenser that condenses the refrigerant discharged from the compressor, first and second receivers configured to store the refrigerant flowing out from the condenser, an expansion valve that depressurizes the refrigerant flowing out from the first and second receivers, and an evaporator that evaporates the refrigerant flowing out from the expansion valve. The injection circuit includes an injection expansion valve that depressurizes the refrigerant flowing out from the main circuit and is connected to the intermediate pressure side or suction side of the compressor. The internal heat exchanger is configured to exchange heat between the refrigerant flowing through the main circuit and the refrigerant flowing out from the injection expansion valve in the injection circuit. The degassing circuit is connected to the injection circuit between the first and second receivers, the injection expansion valve, and the internal heat exchanger. The refrigerant is a supercritical refrigerant. The degassing circuit includes a degassing pipe and a degassing valve connected to the degassing pipe. The gas vent valve is configured to be able to open and close the gas vent circuit.

[0008] According to the refrigeration cycle device of the present disclosure, even if the volume of the receiver is limited, it is possible to store a sufficient amount of supercritical refrigerant, and it is possible to control the pressure in the receiver by venting the gas.

[0009] It is a refrigerant circuit diagram of a refrigeration cycle device according to an embodiment. It is an enlarged view schematically showing a first receiver and a second receiver and a gas vent valve of the refrigeration cycle device according to the embodiment. It is a refrigerant circuit diagram of a modified example 1 of the refrigeration cycle device according to the embodiment. It is an enlarged view schematically showing a first receiver and a second receiver and a gas vent valve of a modified example 2 of the refrigeration cycle device according to the embodiment.

[0010] Hereinafter, embodiments will be described with reference to the drawings. In the following, the same or corresponding parts will be denoted by the same reference numerals, and overlapping descriptions will not be repeated.

[0011] A configuration of a refrigeration cycle apparatus 100 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a refrigerant circuit diagram of the refrigeration cycle apparatus 100 according to the embodiment. The refrigeration cycle apparatus 100 according to the embodiment is, for example, a refrigerator.

[0012] 1 , the refrigeration cycle apparatus 100 according to the embodiment includes a main circuit MC, an injection circuit IC, a gas vent circuit GC, and an internal heat exchanger 10. The refrigeration cycle apparatus 100 according to the embodiment also includes a downstream injection circuit DC, a downstream internal heat exchanger 11, and a control device 20.

[0013] The refrigerant circulating in the refrigeration cycle device 100 is a supercritical refrigerant. The supercritical refrigerant is a refrigerant used in a state where the pressure of the refrigerant exceeds the critical pressure (supercritical state). The supercritical refrigerant is, for example, carbon dioxide (CO ２ )

[0014] The main circuit MC has a compressor 1, a condenser 2, an expansion valve 3, an evaporator 4, and multiple receivers 5. The main circuit MC is configured by connecting the compressor 1, the condenser 2, the expansion valve 3, the evaporator 4, and the multiple receivers 5 with piping. The main circuit MC is configured so that the refrigerant flows through the compressor 1, the condenser 2, the multiple receivers 5, the expansion valve 3, and the evaporator 4 in this order.

[0015] In this embodiment, the main circuit MC has a first receiver 5a and a second receiver 5b as the multiple receivers 5. In addition, in this embodiment, the main circuit MC has a two-stage throttle valve 6.

[0016] The compressor 1 is configured to compress a refrigerant until the pressure of the refrigerant exceeds the critical pressure (supercritical state). The compressor 1 is configured to compress the refrigerant that it draws in and discharges it. The compressor 1 has an intermediate pressure port P1 provided on the intermediate pressure side, a suction port P2 provided on the suction side, and a discharge port P3 provided on the discharge side.

[0017] The compressor 1 may be configured to have a variable capacity. The compressor 1 may be configured such that the capacity is changed by adjusting the rotation speed through changing the frequency based on an instruction from the control device 20.

[0018] The condenser 2 is configured to condense the refrigerant discharged from the compressor 1. The condenser 2 is configured to cool and condense the refrigerant discharged from the compressor 1. The condenser 2 is, for example, a fin-and-tube heat exchanger having a plurality of fins and a heat transfer tube passing through the plurality of fins.

[0019] The expansion valve 3 is configured to reduce the pressure of the refrigerant flowing out from the first receiver 5 a and the second receiver 5 b. The expansion valve 3 is, for example, a solenoid valve. The expansion valve 3 is configured to be able to adjust the flow rate of the refrigerant based on an instruction from the control device 20.

[0020] The evaporator 4 is configured to evaporate the refrigerant that flows out from the expansion valve 3. The evaporator 4 is configured to heat and evaporate the refrigerant that flows out from the expansion valve 3. The evaporator 4 is, for example, a fin-and-tube heat exchanger having a plurality of fins and a heat transfer tube that passes through the plurality of fins.

[0021] In this embodiment, the multiple receivers 5 include a first receiver 5a and a second receiver 5b. The first receiver 5a and the second receiver 5b are configured to be able to store the refrigerant that flows out from the condenser 2. The first receiver 5a and the second receiver 5b are configured to be able to store liquefied refrigerant. The first receiver 5a and the second receiver 5b are configured to be able to store surplus refrigerant. In this embodiment, the first receiver 5a and the second receiver 5b are configured to be able to store the refrigerant that flows out from the condenser 2 and has been decompressed by the two-stage throttle valve 6.

[0022] In this embodiment, the first receiver 5a and the second receiver 5b are connected in series with each other. In the main circuit MC, the first receiver 5a is arranged upstream of the refrigerant flow, and the second receiver 5b is arranged downstream of the refrigerant flow.

[0023] The two-stage throttle valve 6 is configured to reduce the pressure of the refrigerant flowing out from the condenser 2. The two-stage throttle valve 6 is configured to reduce the pressure of the refrigerant to an intermediate pressure in order to store the refrigerant in a liquid state below its critical pressure. The two-stage throttle valve 6 is, for example, a solenoid valve. The two-stage throttle valve 6 is configured to be able to adjust the flow rate of the refrigerant based on an instruction from the control device 20.

[0024] The injection circuit IC is connected to the main circuit MC and the intermediate pressure side or suction side of the compressor 1. In this embodiment, the injection circuit IC is connected to the main circuit MC and the intermediate pressure side of the compressor 1. In this embodiment, the injection circuit IC is connected to the main circuit MC between the two-stage throttle valve 6 and the internal heat exchanger 10 and the intermediate pressure port P1 of the compressor 1.

[0025] The injection circuit IC has an injection expansion valve 7 that reduces the pressure of the refrigerant flowing out from the main circuit MC. The injection expansion valve 7 is disposed in the injection circuit IC upstream of the internal heat exchanger 10 in the refrigerant flow direction. The injection expansion valve 7 is configured to reduce the pressure of the refrigerant to an intermediate pressure.

[0026] The internal heat exchanger 10 is configured to exchange heat between the refrigerant flowing through the main circuit MC and the refrigerant flowing out of the injection expansion valve 7 in the injection circuit IC. The internal heat exchanger 10 is configured to exchange heat between the refrigerant flowing between the condenser 2 and the first and second receivers 5a and 5b in the main circuit MC and the refrigerant flowing through the injection circuit IC. The internal heat exchanger 10 is configured so that the flow of the refrigerant flowing through the main circuit MC and the flow of the refrigerant flowing through the injection circuit IC are counter-flowing. In other words, the internal heat exchanger 10 is configured so that the flow of the refrigerant flowing through the main circuit MC and the flow of the refrigerant flowing through the injection circuit IC are counter-flowing.

[0027] The vent circuit GC is connected to the first receiver 5a, the second receiver 5b, and the injection circuit IC between the injection expansion valve 7 and the internal heat exchanger 10. The vent circuit GC is connected to the injection circuit IC upstream of the first receiver 5a and the second receiver 5b in the refrigerant flow. The vent circuit GC has a vent pipe GP and a vent valve 8 connected to the vent pipe GP. The vent pipe GP is connected via the vent valve 8 to the injection circuit IC between the first receiver 5a, the second receiver 5b, and the injection expansion valve 7 and the internal heat exchanger 10. The vent valve 8 is configured to open and close the vent circuit GC. The vent valve 8 is, for example, a solenoid valve. The vent valve 8 is configured to open and close based on instructions from the control device 20.

[0028] The gas vent valve 8 has a first valve 8a and a second valve 8b. Each of the first valve 8a and the second valve 8b is configured to be able to open and close the gas vent circuit GC. The first receiver 5a is connected to the first valve 8a. The second receiver 5b is connected to the second valve 8b.

[0029] The downstream injection circuit DC is connected to the main circuit MC and the suction side of the compressor 1. The downstream injection circuit DC is connected to the main circuit MC between the expansion valve 3 and the downstream internal heat exchanger 11, and to the suction port P2 of the compressor 1.

[0030] The downstream injection circuit DC has a downstream injection expansion valve 9a that reduces the pressure of the refrigerant flowing out from the main circuit MC. The downstream injection expansion valve 9a is arranged in the downstream injection circuit DC upstream of the downstream internal heat exchanger 11 in the refrigerant flow direction. The downstream injection expansion valve 9a is configured to reduce the pressure of the refrigerant to a low level.

[0031] The downstream internal heat exchanger 11 is configured to exchange heat between the refrigerant flowing out of the second receiver 5b in the main circuit MC and the refrigerant flowing out of the downstream injection expansion valve 9a in the downstream injection circuit DC. The downstream internal heat exchanger 11 is configured so that the flow of refrigerant flowing through the main circuit MC and the flow of refrigerant flowing through the downstream injection circuit DC are counter-flowing. In other words, the downstream internal heat exchanger 11 is configured so that the flow of refrigerant flowing through the main circuit MC and the flow of refrigerant flowing through the downstream injection circuit DC are counter-flowing.

[0032] The control device 20 is configured to control the entire refrigeration cycle apparatus 100. The control device 20 is configured to control the compressor 1, the expansion valve 3, and the two-stage throttle valve 6 in the main circuit MC. The control device 20 is configured to control the injection expansion valve 7 in the injection circuit IC. The control device 20 is configured to control the gas vent valve 8 in the gas vent circuit GC. The control device 20 is configured to control the first valve 8a and the second valve 8b. The control device 20 is configured to open the second valve 8b connected to the second receiver 5b before opening the first valve 8a connected to the first receiver 5a.

[0033] The control device 20 is configured to control the downstream injection expansion valve 9a in the downstream injection circuit DC. The control device 20 is configured, for example, by a microcomputer. The control device 20 includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc. A control program is stored in the ROM.

[0034] Next, a description will be given of the operation of the refrigeration cycle apparatus 100 according to the embodiment. The operation of the refrigeration cycle apparatus 100 according to the embodiment will be described with reference to Figs.

[0035] The refrigerant that flows into the compressor 1 from the intermediate pressure port P1 and the suction port P2 is compressed by the compressor 1 to become high-temperature, high-pressure gas refrigerant and is discharged from the discharge port P3 of the compressor 1. This high-temperature, high-pressure gas refrigerant flows into the condenser 2, where it is condensed to become liquid refrigerant, and then flows out of the condenser 2.

[0036] This liquid refrigerant flows into the internal heat exchanger 10. The liquid refrigerant flowing out of the internal heat exchanger 10 branches off and flows into the main circuit MC and the injection circuit IC. The liquid refrigerant flowing into the injection circuit IC is reduced in pressure by the injection expansion valve 7 to an intermediate pressure, and flows into the internal heat exchanger 10. The liquid refrigerant flowing into the internal heat exchanger 10 exchanges heat with the liquid refrigerant flowing in the main circuit MC in the internal heat exchanger 10 and becomes gas refrigerant. This gas refrigerant flows into the intermediate pressure port P1 of the compressor 1.

[0037] The liquid refrigerant flowing through the main circuit MC is reduced in pressure by the two-stage throttle valve 6 to an intermediate pressure and flows into the first receiver 5a. The liquid refrigerant flowing out of the first receiver 5a flows into the second receiver 5b. The liquid refrigerant flowing out of the second receiver 5b flows into the downstream internal heat exchanger 11. The liquid refrigerant flowing out of the downstream internal heat exchanger 11 branches and flows into the main circuit MC and the downstream injection circuit DC. The liquid refrigerant flowing into the downstream injection circuit DC is reduced in pressure by the downstream injection expansion valve 9a to a low pressure and flows into the downstream internal heat exchanger 11. The liquid refrigerant flowing into the downstream internal heat exchanger 11 exchanges heat with the liquid refrigerant flowing through the main circuit MC in the downstream internal heat exchanger 11 and becomes gas refrigerant. This gas refrigerant flows into the suction port P2 of the compressor 1.

[0038] The liquid refrigerant flowing through the main circuit MC is decompressed by the expansion valve 3 to become a low-pressure gas-liquid two-phase refrigerant, and flows out of the expansion valve 3. This gas-liquid two-phase refrigerant flows into the evaporator 4, where it is evaporated to become gas refrigerant. This gas refrigerant flows into the suction port P2 of the compressor 1. In this way, the refrigerant circulates through the refrigeration cycle apparatus 100 refrigeration circuit.

[0039] Next, the flow of refrigerant flowing through the first receiver 5a, the second receiver 5b, and the degassing circuit GC will be described. Excess refrigerant occurs depending on the operating state of the refrigeration cycle apparatus 100, the outside air temperature, and the like. The first receiver 5a and the second receiver 5b store this excess refrigerant as liquid refrigerant. With the liquid refrigerant stored in the first receiver 5a and the second receiver 5b, degassing of the first receiver 5a and the second receiver 5b is performed to control the pressure in the first receiver 5a and the second receiver 5b.

[0040] The timing for venting the gas is when the pressure in the first receiver 5a and the second receiver 5b exceeds a predetermined value such as a design pressure. The pressure in the first receiver 5a and the second receiver 5b is measured by, for example, a pressure gauge.

[0041] The first valve 8a connected to the first receiver 5a and the second valve 8b connected to the second receiver 5b may be opened simultaneously to release the gas. Alternatively, the second valve 8b connected to the second receiver 5b may be opened to release the gas from the second receiver 5b, and then the first valve 8a connected to the first receiver 5a may be opened to release the gas from the first receiver 5a.

[0042] Next, a description will be given of a modified example of the refrigeration cycle apparatus 100 according to the embodiment. The modified example of the refrigeration cycle apparatus 100 according to the embodiment has the same configuration and operation as the refrigeration cycle apparatus 100 according to the embodiment unless otherwise specified.

[0043] A first modified example of the refrigeration cycle apparatus 100 according to the embodiment will be described with reference to Fig. 3. Fig. 3 is a refrigerant circuit diagram of the first modified example of the refrigeration cycle apparatus 100 according to the embodiment. The first modified example of the refrigeration cycle apparatus 100 according to the embodiment is different from the refrigeration cycle apparatus 100 according to the embodiment in the injection circuit IC, the internal heat exchanger 10, and the degassing circuit GC. Furthermore, the first modified example of the refrigeration cycle apparatus 100 according to the embodiment is provided with an upstream injection circuit UC instead of the downstream injection circuit DC, as compared to the refrigeration cycle apparatus 100 according to the embodiment.

[0044] In the first modification of the refrigeration cycle apparatus 100 according to the embodiment, the injection circuit IC is connected to the main circuit MC and the suction side of the compressor 1. The injection circuit IC is connected to the main circuit MC between the expansion valve 3 and the internal heat exchanger 10 and to the suction port P2 of the compressor 1.

[0045] The internal heat exchanger 10 is configured to exchange heat between the refrigerant flowing between the first receiver 5a and the second receiver 5b and the expansion valve 3 in the main circuit MC and the refrigerant flowing through the injection circuit IC.

[0046] The gas venting circuit GC is connected to the injection circuit IC downstream of the first receiver 5a and the second receiver 5b in the refrigerant flow.

[0047] The upstream injection circuit UC is connected to the main circuit MC and the intermediate pressure side of the compressor 1. The upstream injection circuit UC is connected to the main circuit MC between the two-stage throttle valve 6 and the upstream internal heat exchanger 12, and to the intermediate pressure port P1 of the compressor 1.

[0048] The upstream injection circuit UC has an upstream injection expansion valve 9b that reduces the pressure of the refrigerant flowing out from the main circuit MC. The upstream injection expansion valve 9b is disposed in the upstream injection circuit UC upstream of the upstream internal heat exchanger 12 in the refrigerant flow direction. The upstream injection expansion valve 9b is configured to reduce the pressure of the refrigerant to an intermediate pressure.

[0049] The upstream internal heat exchanger 12 is configured to exchange heat between the refrigerant flowing out from the condenser 2 in the main circuit MC and the refrigerant flowing out from the upstream injection expansion valve 9b in the upstream injection circuit UC. The upstream internal heat exchanger 12 is configured so that the flow of refrigerant flowing through the main circuit MC and the flow of refrigerant flowing through the upstream injection circuit UC are opposite to each other. In other words, the upstream internal heat exchanger 12 is configured so that the flow of refrigerant flowing through the main circuit MC and the flow of refrigerant flowing through the upstream injection circuit UC are opposite to each other.

[0050] The control device 20 is configured to control the upstream injection expansion valve 9b in the upstream injection circuit UC.

[0051] A second modification of the refrigeration cycle apparatus 100 according to the embodiment will be described with reference to FIG. 4 . FIG. 4 illustrates the first receiver 5a, the second receiver 5b, and the gas vent valve 8 of the second modification of the refrigeration cycle apparatus 100 according to the embodiment. In the second modification of the refrigeration cycle apparatus 100 according to the embodiment, the main circuit MC includes a liquid equalizing pipe LE for equalizing the liquid levels of the refrigerant stored in the first receiver 5a and the second receiver 5b. The liquid equalizing pipe LE is connected to the lower part of each of the first receiver 5a and the second receiver 5b. The liquid equalizing pipe LE is connected to the bottom of each of the first receiver 5a and the second receiver 5b. The gas vent pipe GP includes a pressure equalizing pipe PE for equalizing the pressure of the refrigerant stored in the first receiver 5a and the second receiver 5b. The pressure equalizing pipe PE is connected to the upper part of each of the first receiver 5a and the second receiver 5b. The pressure equalizing pipe PE is connected to the ceiling of each of the first receiver 5a and the second receiver 5b. The pressure equalizing pipe PE is connected to the injection circuit IC via a gas vent valve 8 .

[0052] Next, the effects of the refrigeration cycle apparatus 100 according to the embodiment and the modified example will be described.

[0053] Referring to FIG. 1 , in the refrigeration cycle apparatus 100 according to this embodiment, a vent circuit GC is connected to the first receiver 5a, the second receiver 5b, and an injection circuit IC between the injection expansion valve 7 and the internal heat exchanger 10. The vent valve 8 is configured to be able to open and close the vent circuit GC. Therefore, even if the volume of the receiver 5 is restricted by the specifications of the high-pressure container, the first receiver 5a and the second receiver 5b can store a sufficient amount of supercritical refrigerant. The vent valve 8 opens the vent circuit GC to vent gas, thereby controlling the pressure in the first receiver 5a and the second receiver 5b.

[0054] The gas vent circuit GC is connected to the first receiver 5a, the second receiver 5b, and the injection circuit IC between the injection expansion valve 7 and the internal heat exchanger 10. Therefore, when liquid refrigerant flows out from the first receiver 5a and the second receiver 5b into the gas vent circuit GC, the flowing liquid refrigerant can be evaporated in the internal heat exchanger 10. Therefore, the liquid refrigerant can be prevented from flowing into the compressor 1.

[0055] 1 , in the refrigeration cycle apparatus 100 according to the embodiment, the injection circuit IC is connected to the main circuit MC and the intermediate pressure side of the compressor 1. Therefore, by causing the refrigerant to flow from the injection circuit IC into the intermediate pressure side of the compressor 1, it is possible to eliminate the power required by the compressor 1 to compress the refrigerant from low pressure to intermediate pressure. This improves the energy saving performance of the refrigeration cycle apparatus 100.

[0056] 1 and 2, the first receiver 5a and the second receiver 5b are connected in series. The first receiver 5a is connected to a first valve 8a. The second receiver 5b is connected to a second valve 8b. Therefore, gas can be released from the first receiver 5a and the second receiver 5b by opening the first valve 8a connected to the first receiver 5a and the second valve 8b connected to the second receiver 5b. Furthermore, because there are no restrictions on the installation of the first receiver 5a and the second receiver 5b, even low-height first receivers 5a and second receivers 5b are effective.

[0057] 1 and 2, the control device 20 is configured to open the second valve 8b connected to the second receiver 5b before opening the first valve 8a connected to the first receiver 5a. Therefore, the second valve 8b connected to the second receiver 5b is opened to release gas from the second receiver 5b located downstream in the refrigerant flow, and then the first valve 8a connected to the first receiver 5a is opened to release gas from the first receiver 5a located upstream in the refrigerant flow. Liquid refrigerant increases in the first receiver 5a located upstream, and the second receiver 5b located downstream does not become full of liquid. This ensures reliable gas release.

[0058] 3 , in the first modification of the refrigeration cycle apparatus 100 according to the embodiment, the injection circuit IC is connected to the main circuit MC and the suction side of the compressor 1. Therefore, when the pressure on the intermediate pressure side of the compressor 1 is higher than the pressures of the first receiver 5 a and the second receiver 5 b, the refrigerant can be made to flow into the compressor 1 by flowing from the injection circuit IC into the suction side of the compressor 1.

[0059] Referring to FIG. 4 , in the second modification of the refrigeration cycle apparatus 100 according to the embodiment, the liquid equalizing pipe LE is connected to the lower portion of each of the first receiver 5a and the second receiver 5b. The pressure equalizing pipe PE is connected to the upper portion of each of the first receiver 5a and the second receiver 5b. Therefore, the liquid level of the liquid refrigerant stored in the first receiver 5a and the second receiver 5b can be made uniform by the liquid equalizing pipe LE. In this state, gas can be released from the pressure equalizing pipe PE. Therefore, it is possible to prevent the liquid refrigerant from flowing out of the pressure equalizing pipe PE due to uneven distribution of the liquid refrigerant stored in the first receiver 5a and the second receiver 5b.

[0060] In addition, one gas vent valve 8 is connected to the pressure equalizing pipe PE. Therefore, the number of gas vent valves 8 can be minimized.

[0061] According to the refrigeration cycle apparatus 100 of the embodiment and the modified example, the supercritical refrigerant is carbon dioxide, and therefore carbon dioxide can be suitably used as the supercritical refrigerant.

[0062] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0063] 1 Compressor, 2 Condenser, 3 Expansion valve, 4 Evaporator, 5 Receiver, 5a First receiver, 5b Second receiver, 6 Two-stage throttle valve, 7 Injection expansion valve, 8 Gas vent valve, 8a First valve, 8b Second valve, 9a Downstream injection expansion valve, 9b Upstream injection expansion valve, 10 Internal heat exchanger, 11 Downstream internal heat exchanger, 12 Upstream internal heat exchanger, 20 Control device, 100 Refrigeration cycle device, DC Downstream injection circuit, GC Gas vent circuit, GP Gas vent pipe, IC Injection circuit, LE Liquid equalizing pipe, MC Main circuit, PE Pressure equalizing pipe, UC Upstream injection circuit.

Claims

1. A compressor for compressing a refrigerant, a condenser for condensing the refrigerant discharged from the compressor, a first receiver and a second receiver configured to store the refrigerant flowing out from the condenser, an expansion valve for reducing the pressure of the refrigerant flowing out from the first receiver and the second receiver, and an evaporator for evaporating the refrigerant flowing out from the expansion valve; an injection circuit having an injection expansion valve for reducing the pressure of the refrigerant flowing out from the main circuit, and connected to the main circuit and the intermediate pressure side or the suction side of the compressor; an internal heat exchanger configured to exchange heat between the refrigerant flowing through the main circuit and the refrigerant flowing out from the injection expansion valve in the injection circuit; and a gas venting circuit connected to the injection circuit between the first receiver, the second receiver, the injection expansion valve and the internal heat exchanger, wherein the refrigerant is a supercritical refrigerant, and the gas venting circuit has a gas venting pipe and a gas venting valve connected to the gas venting pipe, The gas vent valve is configured to be able to open and close the gas vent circuit.

2. A refrigeration cycle device as described in claim 1, wherein the injection circuit is connected to the main circuit and the intermediate pressure side of the compressor, and the internal heat exchanger is configured to exchange heat between the refrigerant flowing between the condenser and the first receiver and the second receiver in the main circuit and the refrigerant flowing through the injection circuit.

3. A refrigeration cycle device as described in claim 1, wherein the injection circuit is connected to the main circuit and the suction side of the compressor, and the internal heat exchanger is configured to exchange heat between the refrigerant flowing between the first receiver and the second receiver and the expansion valve in the main circuit and the refrigerant flowing through the injection circuit.

4. A refrigeration cycle device as described in any one of claims 1 to 3, wherein the first receiver and the second receiver are connected in series to each other, the gas vent valve has a first valve and a second valve, each of the first valve and the second valve is configured to be able to open and close the gas vent circuit, the first receiver is connected to the first valve, and the second receiver is connected to the second valve.

5. A refrigeration cycle apparatus as described in claim 4, further comprising a control device configured to control the first valve and the second valve, wherein in the main circuit, the first receiver is arranged upstream of the refrigerant flow and the second receiver is arranged downstream of the refrigerant flow, and the control device is configured to open the second valve connected to the second receiver and then open the first valve connected to the first receiver.

6. A refrigeration cycle apparatus as claimed in any one of claims 1 to 3, wherein the main circuit has a liquid equalizing pipe for equalizing the liquid levels of the refrigerant stored in the first receiver and the second receiver, the liquid equalizing pipe being connected to the lower part of each of the first receiver and the second receiver, the gas vent pipe has a pressure equalizing pipe for equalizing the pressures of the refrigerant stored in the first receiver and the second receiver, and the pressure equalizing pipe is connected to the upper part of each of the first receiver and the second receiver.

7. A refrigeration cycle device according to any one of claims 1 to 6, wherein the supercritical refrigerant is carbon dioxide.

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