Use as refrigerant and refrigeration cycle apparatus

Abstract

Suppressing pressure rise within the compressor. A composition used as a refrigerant in a refrigerant circuit (10), the composition comprising one or more of the group consisting of ethylene-based fluoroolefins, 2,3,3,3-tetrafluoropropylene (HFO-1234yf) and 1,3,3,3-tetrafluoropropylene (HFO-1234ze), wherein the internal volume of the refrigerant piping (11, 12, 13, 15, 5, 19, 18, 6, 14) and components (23, 31, 24, 41) connected to the compressor (21) in the refrigerant circuit (10) is at least 0.7 times the internal volume of the compressor.

Description

Technical Field

[0001] This relates to its use as a refrigerant and refrigeration cycle devices. Background Technology

[0002] Previously, hydrofluoroolefins (HFO refrigerants) with lower Global Warming Potential (GWP) than HFC refrigerants have been of interest in refrigeration devices. For example, 1,2-difluoroethylene (HFO-1132) was also studied as a refrigerant with low GWP in Patent Document 1 (Japanese Patent Application Publication No. 2019-196312). Summary of the Invention

[0003] The problem that the invention aims to solve

[0004] Although this HFO refrigerant has a low GWP, it also has low stability. Therefore, under certain conditions, it is sometimes prone to a self-decomposition reaction known as disproportionation. A disproportionation reaction refers to a chemical reaction in which two or more molecules of the same kind react with each other to transform into two or more different kinds of substances.

[0005] If such a disproportionation reaction of HFO refrigerant occurs inside the compressor, the pressure inside the compressor may rise sharply.

[0006] The purpose of this invention is to suppress the rapid rise in pressure inside the compressor.

[0007] Methods for solving problems

[0008] The inventors of this application conducted repeated and in-depth research to suppress the propagation of refrigerant disproportionation reactions. As a result, they discovered that even if a refrigerant disproportionation reaction occurs, a rapid increase in the internal pressure of the compressor can be suppressed even with a large internal volume of the connection material to the compressor. Based on the above insights, the inventors of this application conducted further repeated research, thereby completing the content of this invention. This invention provides the following uses as a refrigerant and refrigeration cycle apparatus.

[0009] The first viewpoint's use as a refrigerant refers to the use of the composition as a refrigerant in a refrigerant circuit. The refrigerant circuit includes a compressor, refrigerant piping connected to the compressor, and components. The internal volume of the refrigerant piping and components is at least 0.7 times the internal volume of the compressor. The composition comprises one or more of the following: fluoroolefins selected from the group consisting of ethylene-based fluoroolefins, 2,3,3,3-tetrafluoropropylene (HFO-1234yf), and 1,3,3,3-tetrafluoropropylene (HFO-1234ze).

[0010] It should be noted that the internal volume of the refrigerant piping and components is preferably 1.0 times or more than the internal volume of the compressor, more preferably 2.0 times or more, and even more preferably 5.0 times or more.

[0011] Depending on its intended use as a refrigerant, even if a disproportionation reaction occurs within the compressor, it can suppress a sharp rise in pressure inside the compressor.

[0012] The second viewpoint is the same as the first viewpoint, wherein the composition comprises one or more of the following: 1,2-difluoroethylene (HFO-1132), 1,1-difluoroethylene (HFO-1132a), 1,1,2-trifluoroethylene (HFO-1123), monofluoroethylene (HFO-1141), trifluorochloroethylene (CFO-1113), and perfluoroolefins.

[0013] It should be noted that 1,2-difluoroethylene can be trans-1,2-difluoroethylene [(E)-HFO-1132], cis-1,2-difluoroethylene [(Z)-HFO-1132], or a mixture thereof.

[0014] The use of the third viewpoint is the same as the use of the second viewpoint as a refrigerant, wherein the composition comprises 1,2-difluoroethylene (HFO-1132) and / or 1,1,2-trifluoroethylene (HFO-1123).

[0015] The refrigeration cycle device of the fourth viewpoint includes a refrigerant circuit that uses one or more compositions of a group consisting of fluoroolefins selected from the ethylene group, 2,3,3,3-tetrafluoropropylene (HFO-1234yf), and 1,3,3,3-tetrafluoropropylene (HFO-1234ze) as a refrigerant. The refrigerant circuit includes a compressor, refrigerant piping connected to the compressor, and other components. The internal volume of the refrigerant piping and other components is at least 0.7 times the internal volume of the compressor.

[0016] It should be noted that the internal volume of the refrigerant piping and components is preferably 1.0 times or more than the internal volume of the compressor, more preferably 2.0 times or more, and even more preferably 5.0 times or more.

[0017] This compressor can suppress the propagation of refrigerant disproportionation reaction inside the compressor by controlling the refrigerant's passage through designated areas around the ignition energy generation site. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the refrigeration cycle device.

[0019] Figure 2 This is a block diagram of a refrigeration cycle device.

[0020] Figure 3 This is a schematic diagram illustrating the test apparatus used in Test Example 1 concerning the pressure increase caused by the disproportionation reaction.

[0021] Figure 4 This is a schematic diagram illustrating the test apparatus used in Test Examples 2-6 concerning the pressure increase caused by the disproportionation reaction. Detailed Implementation

[0022] The following examples illustrate the use of the refrigerant of the present invention in a refrigeration cycle device and the refrigeration cycle device in detail, but these descriptions do not limit the scope of the present invention.

[0023] (1) Refrigeration cycle device 1

[0024] The refrigeration cycle device 1 is a device that processes the heat load of the target space by performing a vapor compression refrigeration cycle, such as an air conditioning device for regulating the air in the target space.

[0025] Figure 1 The diagram shows a schematic configuration of the refrigeration cycle device. Figure 2 The diagram shows a block diagram of the refrigeration cycle device.

[0026] The refrigeration cycle device 1 mainly includes: an outdoor unit 20; an indoor unit 30; a liquid-side refrigerant connecting pipe 6 and a gas-side refrigerant connecting pipe 5 connecting the outdoor unit 20 and the indoor unit 30; a remote control (not shown); and a controller 7 for controlling the operation of the refrigeration cycle device 1.

[0027] In the refrigeration cycle device 1, the following refrigeration cycle is performed: the refrigerant sealed in the refrigerant circuit 10 is compressed, cooled or condensed, depressurized, heated or evaporated, and then compressed again. In this embodiment, the refrigerant circuit 10 is filled with refrigerant for performing a vapor compression refrigeration cycle.

[0028] (2) Refrigerant

[0029] The refrigerant filled in the refrigerant circuit 10 is one or more refrigerants selected from the group consisting of fluoroolefins selected from ethylene groups, 2,3,3,3-tetrafluoropropylene (HFO-1234yf), and 1,3,3,3-tetrafluoropropylene (HFO-1234ze). It should be noted that, regarding the combustion rate as defined in ISO 817, 1.2 cm / s for 1,3,3,3-tetrafluoropropylene (HFO-1234ze) is lower than 1.5 cm / s for 2,3,3,3-tetrafluoropropylene (HFO-1234yf), and is therefore preferred. Furthermore, regarding the Lower Flammability Limit (LFL) defined in ISO 817, 1,3,3,3-tetrafluoropropylene (HFO-1234ze) at 65,000 vol.ppm (6.5%) is preferred over 2,3,3,3-tetrafluoropropylene (HFO-1234yf) at 62,000 vol.ppm (6.2%). The refrigerant may contain one or more of the following: 1,2-difluoroethylene (HFO-1132), 1,1-difluoroethylene (HFO-1132a), 1,1,2-trifluoroethylene (HFO-1123), monofluoroethylene (HFO-1141), trifluorochloroethylene (CFO-1113), and perfluoroolefins. The refrigerant is particularly preferably composed of 1,2-difluoroethylene (HFO-1132) and / or 1,1,2-trifluoroethylene (HFO-1123).

[0030] Examples of fluoroolefins derived from the ethylene family include 1,2-difluoroethylene (HFO-1132), 1,1-difluoroethylene (HFO-1132a), 1,1,2-trifluoroethylene (HFO-1123), monofluoroethylene (HFO-1141), trifluorochloroethylene (CFO-1113), and perfluoroolefins. Examples of perfluoroolefins include tetrafluoroethylene (FO-1114).

[0031] It should be noted that refrigeration oil is filled in the refrigerant circuit 10 along with the refrigerant.

[0032] (3) Outdoor Unit 20

[0033] The outdoor unit 20 is connected to the indoor unit 30 via the liquid-side refrigerant connecting pipe 6 and the gas-side refrigerant connecting pipe 5, forming part of the refrigerant circuit 10. The outdoor unit 20 mainly includes a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion valve 24, an outdoor fan 25, a receiver 41, a gas-side shut-off valve 28, a liquid-side shut-off valve 29, and the first refrigerant pipe 11 to the seventh refrigerant pipe 17.

[0034] Compressor 21 is a device that compresses low-pressure refrigerant to high pressure in the refrigeration cycle. Here, compressor 21 can be a hermetically sealed compressor driven by a compressor motor, such as a rotary or scroll compressor. In this embodiment, a rotary compressor is used. The compressor motor is used to change capacity, and its operating frequency can be controlled by an inverter. A seventh refrigerant pipe 17, serving as a suction pipe, is connected to the suction side of compressor 21. A first refrigerant pipe 11, serving as a discharge pipe, is connected to the discharge side of compressor 21.

[0035] The four-way switching valve 22 is a valve that switches the flow path by controlling the movement of a valve body (not shown), and it switches the refrigerant circuit 10 to a cooling connection state and a heating connection state. Specifically, in the cooling connection state, the four-way switching valve 22 is switched to the following state: connecting the first refrigerant pipe 11 connected to the discharge side of the compressor 21 and the second refrigerant pipe 12 connected to the outdoor heat exchanger 23, and connecting the seventh refrigerant pipe 17, the receiver 41, the sixth refrigerant pipe 16 connected to the suction side of the compressor 21, and the fifth refrigerant pipe 15 connected to the gas-side shut-off valve 28. In addition, the four-way switching valve 22 is switched to the following state in the heating connection state: the first refrigerant pipe 11 connected to the discharge side of the compressor 21 and the fifth refrigerant pipe 15 connected to the gas side shut-off valve 28 are connected, and the seventh refrigerant pipe 17, receiver 41, sixth refrigerant pipe 16 connected to the suction side of the compressor 21 and the second refrigerant pipe 12 connected to the outdoor heat exchanger 23 are connected.

[0036] The outdoor heat exchanger 23 functions as a radiator or condenser for the high-pressure refrigerant in the refrigeration cycle during cooling operation and as an evaporator for the low-pressure refrigerant in the refrigeration cycle during heating operation. The gas-side end of the outdoor heat exchanger 23 is connected to the four-way switching valve 22 via the second refrigerant pipe 12. The liquid-side end of the outdoor heat exchanger 23 is connected to the expansion valve 24 via the third refrigerant pipe 13.

[0037] Expansion valve 24 is located between the liquid-side outlet of the outdoor heat exchanger 23 in the refrigerant circuit 10 and the liquid-side shut-off valve 29. Expansion valve 24 is an electrically operated expansion valve whose opening is adjusted by controlling a valve body (not shown) through movement of a valve seat (not shown). Expansion valve 24 and liquid-side shut-off valve 29 are connected via a fourth refrigerant pipe 14.

[0038] Outdoor fan 25 draws outdoor air into outdoor unit 20, where it exchanges heat with refrigerant in outdoor heat exchanger 23, generating an airflow to be exhausted to the outside. Outdoor fan 25 is driven by outdoor fan motor.

[0039] The receiver 41 is located between the suction side of the compressor 21 and one of the connection ports of the four-way switching valve 22, and is a refrigerant container capable of storing the remaining refrigerant in the refrigerant circuit 10 as liquid refrigerant. The inlet side of the receiver 41 is connected to the four-way switching valve 22 via the sixth refrigerant pipe 16. The outlet side of the receiver 41 is connected to the suction side of the compressor 21 via the seventh refrigerant pipe 17.

[0040] The liquid-side shut-off valve 29 is a manual valve located in the outdoor unit 20 at the connection point of the refrigerant-connected piping 6.

[0041] The gas-side shut-off valve 28 is a manual valve located in the outdoor unit 20 at the connection point of the gas-side refrigerant connecting pipe 5.

[0042] The outdoor unit 20 has an outdoor unit control unit 27, which controls the operation of each component constituting the outdoor unit 20. The outdoor unit control unit 27 has a microcomputer including a CPU, memory, etc. The outdoor unit control unit 27 is connected to the indoor unit control unit 34 of each indoor unit 30 via a communication line to transmit and receive control signals, etc.

[0043] The outdoor unit 20 is equipped with a discharge pressure sensor 61, a discharge temperature sensor 62, a suction pressure sensor 63, a suction temperature sensor 64, an outdoor heat exchange temperature sensor 65, and an external gas temperature sensor 66. These sensors are electrically connected to the outdoor unit control unit 27 and send detection signals to it. The discharge pressure sensor 61 detects the pressure of the refrigerant flowing in the discharge pipe (i.e., the first refrigerant pipe 11) that connects the discharge side of the compressor 21 to one of the connection ports of the four-way switching valve 22. The discharge temperature sensor 62 detects the temperature of the refrigerant flowing in the discharge pipe (i.e., the first refrigerant pipe 11). The suction pressure sensor 63 detects the pressure of the refrigerant flowing in the suction pipe (i.e., the seventh refrigerant pipe 17) that connects the suction side of the compressor 21 to the receiver 41. The suction temperature sensor 64 detects the temperature of the refrigerant flowing in the suction pipe (i.e., the seventh refrigerant pipe 17). The outdoor heat exchange temperature sensor 65 detects the temperature of the refrigerant flowing through the outlet on the liquid side of the outdoor heat exchanger 23, opposite to the side connected to the four-way switching valve 22. The outdoor gas temperature sensor 66 detects the outdoor air temperature before it passes through the outdoor heat exchanger 23.

[0044] (4) Indoor Unit 30

[0045] The indoor unit 30 is installed, for example, on the wall or ceiling of the interior space that is the target space. The indoor unit 30 is connected to the outdoor unit 20 via the liquid-side refrigerant connecting pipe 6 and the gas-side refrigerant connecting pipe 5, forming part of the refrigerant circuit 10.

[0046] The indoor unit 30 includes an indoor heat exchanger 31, an eighth refrigerant piping 18, a ninth refrigerant piping 19, and an indoor fan 32.

[0047] In the indoor heat exchanger 31, the liquid side is connected to the liquid-side refrigerant connecting pipe 6 via the 8th refrigerant pipe 18, and the gas side is connected to the gas-side refrigerant connecting pipe 5 via the 9th refrigerant pipe 19. The indoor heat exchanger 31 functions as an evaporator for the low-pressure refrigerant in the refrigeration cycle during cooling operation and as a condenser for the high-pressure refrigerant in the refrigeration cycle during heating operation.

[0048] The indoor fan 32 draws indoor air into the indoor unit 30, where it exchanges heat with the refrigerant in the indoor heat exchanger 31, generating an airflow to be exhausted to the outside. The indoor fan 32 is driven by an indoor fan motor.

[0049] In addition, the indoor unit 30 has an indoor unit control unit 34, which controls the operation of each component constituting the indoor unit 30. The indoor unit control unit 34 has a microcomputer including a CPU, memory, etc. The indoor unit control unit 34 is connected to the outdoor unit control unit 27 via a communication line to transmit and receive control signals, etc.

[0050] The indoor unit 30 is equipped with an indoor liquid-side heat exchange temperature sensor 71, an indoor air temperature sensor 72, etc. These sensors are electrically connected to the indoor unit control unit 34 and send detection signals to it. The indoor liquid-side heat exchange temperature sensor 71 detects the temperature of the refrigerant flowing through the outlet on the liquid refrigerant side of the indoor heat exchanger 31. The indoor air temperature sensor 72 detects the indoor air temperature before it passes through the indoor heat exchanger 31.

[0051] (5) Controller 7

[0052] In the refrigeration cycle unit 1, the outdoor unit control unit 27 and the indoor unit control unit 34 are connected via a communication line, thereby forming a controller 7 that controls the operation of the refrigeration cycle unit 1.

[0053] The controller 7 mainly has a CPU (central processing unit) and memory such as ROM and RAM. It should be noted that the various processing and control based on the controller 7 are realized by the integrated functions of the various parts included in the outdoor unit control unit 27 and / or the indoor unit control unit 34.

[0054] (6) Operating Mode

[0055] The refrigeration cycle device 1 is capable of performing at least a refrigeration operation mode and a heating operation mode.

[0056] The controller 7 determines whether it is in cooling or heating operation mode based on instructions received from the remote control or other means, and then executes the command.

[0057] In the refrigeration operation mode, the compressor 21, for example, performs capacity control on the operating frequency to ensure that the evaporation temperature of the refrigerant in the refrigerant circuit 10 reaches the target evaporation temperature.

[0058] The gaseous refrigerant discharged from compressor 21 passes through first refrigerant pipe 11, four-way switching valve 22, and second refrigerant pipe 12, and then condenses in outdoor heat exchanger 23. The refrigerant flowing through outdoor heat exchanger 23 is depressurized after passing through third refrigerant pipe 13 and expansion valve 24.

[0059] The refrigerant, depressurized by expansion valve 24, flows through the fourth refrigerant pipe 14 and then through the liquid-side shut-off valve 29 in the liquid-side refrigerant connecting pipe 6, and is delivered to the indoor unit 30. Afterwards, the refrigerant passes through the eighth refrigerant pipe 18, evaporates in the indoor heat exchanger 31, and then flows through the ninth refrigerant pipe 19 to the gas-side refrigerant connecting pipe 5. The refrigerant flowing through the gas-side refrigerant connecting pipe 5 passes through the gas-side shut-off valve 28, the fifth refrigerant pipe 15, the four-way switching valve 22, the sixth refrigerant pipe 16, the receiver 41, and the seventh refrigerant pipe 17, before being drawn back into the compressor 21.

[0060] In heating operation mode, compressor 21, for example, performs capacity control on the operating frequency to ensure that the condensation temperature of the refrigerant in refrigerant circuit 10 reaches the target condensation temperature.

[0061] The gaseous refrigerant discharged from compressor 21 flows through refrigerant piping 11, four-way switching valve 22, refrigerant piping 15, and gas-side refrigerant connecting piping 5 before being delivered to indoor unit 30. Afterward, the refrigerant flows through refrigerant piping 19 to the gas-side end of indoor heat exchanger 31, where it condenses or releases heat. The refrigerant that has condensed or released heat in indoor heat exchanger 31 then flows through refrigerant piping 18, liquid-side refrigerant connecting piping 6, and into outdoor unit 20.

[0062] The refrigerant passing through the liquid-side shut-off valve 29 of the outdoor unit 20 is depressurized at the expansion valve 24 after passing through the fourth refrigerant pipe 14. The refrigerant depressurized at the expansion valve 24 then passes through the third refrigerant pipe 13, evaporates in the outdoor heat exchanger 23, and is drawn back into the compressor 21 after passing through the second refrigerant pipe 12, the four-way switching valve 22, the sixth refrigerant pipe 16, the receiver 41, and the seventh refrigerant pipe 17.

[0063] (7) Relationship between volume

[0064] In the refrigerant circuit 10 of the refrigeration cycle device 1 of this embodiment, the total internal volume of the first refrigerant pipe 11, the four-way switching valve 22, the second refrigerant pipe 12, the outdoor heat exchanger 23, the third refrigerant pipe 13, and the expansion valve 24 is at least 0.7 times the internal volume of the compressor 21.

[0065] Furthermore, in the refrigerant circuit 10 of the refrigeration cycle device 1 of this embodiment, the total volume of the first refrigerant pipe 11, the four-way switching valve 22, the fifth refrigerant pipe 15, the gas-side refrigerant connecting pipe 5, the ninth refrigerant pipe 19, the indoor heat exchanger 31, the eighth refrigerant pipe 18, the liquid-side refrigerant connecting pipe 6, the fourth refrigerant pipe 14, and the expansion valve 24 is at least 0.7 times the volume of the compressor 21.

[0066] Here, the internal volume can be the volume of refrigerant that can be filled under specified temperature conditions when the system is not in operation.

[0067] (8) Features of the implementation method

[0068] In the refrigeration cycle apparatus 1 of this embodiment, a refrigerant that may undergo a disproportionation reaction under specified conditions is used. In the refrigerant circuit 10, the refrigerant is prone to becoming a high-pressure state at high temperatures, and the possibility of a disproportionation reaction occurring in the compressor 21, where electrical energy may be generated at electrical contacts and frictional heat may be generated at sliding parts, is high. Moreover, if a disproportionation reaction occurs in the compressor 21, the internal pressure may rise sharply. Thus, the rapidly rising pressure inside the compressor 21 may exceed four times the design pressure obtained in the compressor design strength verification test (for example, referring to JIS B8240:2015 Structure of Refrigeration Pressure Vessels, "8 Verification of Design Strength of Pressure Vessels with Complex Structures"), and the reliability of the compressor 21 is considered a problem.

[0069] In contrast, the inventors of this application have confirmed through the test results described below that when the combined internal volume of the refrigerant piping 70 connected to the first pressure vessel 50 and the second pressure vessel 60 is more than 0.7 times the internal volume of the first pressure vessel 50 where the disproportionation reaction occurs, even if the disproportionation reaction occurs, the sharp rise in internal pressure of the first pressure vessel 50 can be suppressed.

[0070] Specifically, the trial use Figure 3 The experimental setup shown and Figure 4 The test was conducted using the apparatus shown.

[0071] exist Figure 3In the test apparatus, a first pressure vessel 50 with a cylindrical internal space and constructed of SUS was used. The internal volume of the first pressure vessel 50 is 35 cc. Additionally, the first pressure vessel 50 is equipped with a temperature sensor to detect the temperature of the refrigerant inside and a pressure sensor to detect the pressure of the refrigerant inside. At the center of the internal space of the first pressure vessel 50, an ignition source S, serving as a platinum wire, is positioned to connect two electrodes. In Test Example 1, using... Figure 3 The test apparatus was filled with 1,2-difluoroethylene (HFO-1132(E)) as a refrigerant in the first pressure vessel 50. The temperature of the refrigerant was set to 150°C and the pressure of the refrigerant was set to 1.2 MPa. A disproportionation reaction occurred at the ignition source S.

[0072] exist Figure 4 In the test apparatus, the same as in Figure 3 The test apparatus uses the same first pressure vessel 50 as the second pressure vessel 60, and the first pressure vessel 50 and the second pressure vessel 60 are connected by a refrigerant piping 70. Both the first pressure vessel 50 and the second pressure vessel 60 are containers with cylindrical internal spaces, constructed of SUS (Supersonic Usage). During the test, temperature sensors for detecting the temperature of the refrigerant inside the first pressure vessel 50 and pressure sensors for detecting the pressure of the refrigerant inside the second pressure vessel 60 are provided for each. Furthermore, the refrigerant piping 70 is a 1 / 4-inch SUS refrigerant piping with a length of 20 cm extending from the circumference of the first pressure vessel 50 to the circumference of the second pressure vessel 60. Figure 3 Similarly, in the test apparatus, at the center of the internal space of the first pressure vessel 50, there is an ignition source S, which serves as a platinum wire, arranged to connect the two electrodes. Figure 4 In the test apparatus, the first pressure vessel 50, the second pressure vessel 60, and the refrigerant piping 70 were filled with 1,2-difluoroethylene (HFO-1132(E)) as the refrigerant. The refrigerant temperature was set to 150°C, and the refrigerant pressure was set to 1.2 MPa. A disproportionation reaction occurred at the ignition source S. It should be noted that in Test Examples 2-6, 1,2-difluoroethylene (HFO-1132(E)) was used as the refrigerant. Figure 4 The experimental apparatus described herein involved setting the internal volume of the first pressure vessel 50 to 35 cc and changing the internal volume of the second pressure vessel 60 to induce a disproportionation reaction. The differences in the pressure rise inside the first pressure vessel 50 were observed. The results of each experimental example are shown below.

[0073] It should be noted that in the following table, "overall volume" refers to the combined internal volume of the first pressure vessel and the second pressure vessel. Additionally, "internal volume ratio" is the value obtained by dividing the internal volume of the second pressure vessel by the internal volume of the first pressure vessel.

[0074] Furthermore, the "theoretical value" of "maximum pressure" represents the maximum pressure detected by the pressure sensor inside the first pressure vessel, assuming that all the refrigerant inside the first pressure vessel decomposes due to the disproportionation reaction, and that no disproportionation reaction of the refrigerant occurs in the second pressure vessel. It should be noted that in Test Example 1, where all the refrigerant inside the first pressure vessel decomposes due to the disproportionation reaction, the pressure inside the first pressure vessel before the disproportionation reaction (1.2 MPa) rose to 9.6 MPa. Therefore, it was confirmed that the pressure inside the first pressure vessel reached 8.0 times (9.6 MPa / 1.2 MPa) due to the refrigerant decomposition caused by the disproportionation reaction. Therefore, the "theoretical value" of "maximum pressure" is obtained by calculating (pressure inside the first pressure vessel before the disproportionation reaction × refrigerant decomposition rate × 8.0) + (pressure inside the first pressure vessel before the disproportionation reaction × (100 - decomposition rate)). It should be noted that the "pressure change rate" as a "theoretical value" is the value obtained by dividing the "maximum pressure" as a "theoretical value" by the pressure inside the first pressure vessel before the disproportionation reaction occurs.

[0075] Additionally, the "maximum pressure" as a "measured value" represents the maximum pressure detected by the pressure sensor inside the first pressure vessel during the disproportionation reaction. The "pressure change rate" as a "measured value" represents the value obtained by dividing the "maximum pressure" as a "measured value" by the pressure inside the first pressure vessel before the disproportionation reaction occurs.

[0076] Table 1

[0077]

[0078] Based on the above test results, it can be seen that the larger the ratio of the internal volume of the second pressure vessel 60 to the internal volume of the first pressure vessel 50, the greater the tendency to suppress pressure rise even when a disproportionation reaction occurs within the first pressure vessel 50. In particular, by ensuring that the internal volume of the second pressure vessel 60 is at least 0.7 times that of the first pressure vessel 50, the pressure change rate under disproportionation reaction conditions can be suppressed to below 4.0, which is within the range of the compressor's design strength verification test (pressure four times the design pressure). Therefore, it can be concluded that the compressor's reliability can be ensured. It should be noted that comparing the "pressure change rate" in the "theoretical value" and the "pressure change rate" in the "measured value" of Table 1, it can be seen that the pressure increase can be suppressed in terms of the measured value. Therefore, by connecting the second pressure vessel 60 to the first pressure vessel 50 via the refrigerant piping 70, the pressure rise can be suppressed to a value smaller than expected.

[0079] Furthermore, in the refrigeration cycle device 1 of this embodiment, the total internal volume of the first refrigerant pipe 11, the four-way switching valve 22, the second refrigerant pipe 12, the outdoor heat exchanger 23, the third refrigerant pipe 13, and the expansion valve 24 is at least 0.7 times the internal volume of the compressor 21. Therefore, even if a disproportionation reaction occurs inside the compressor 21 during refrigeration operation, the pressure rise inside the compressor 21 can be suppressed to less than 4.0 times. Additionally, the total internal volume of the first refrigerant pipe 11, the four-way switching valve 22, the fifth refrigerant pipe 15, the gas-side refrigerant connecting pipe 5, the ninth refrigerant pipe 19, the indoor heat exchanger 31, the eighth refrigerant pipe 18, the liquid-side refrigerant connecting pipe 6, the fourth refrigerant pipe 14, and the expansion valve 24 is at least 0.7 times the internal volume of the compressor 21. Therefore, even if a disproportionation reaction occurs inside the compressor 21 during heating operation, the pressure rise inside the compressor 21 can be suppressed to below 4.0 times.

[0080] Therefore, the reliability of the compressor 21 in the refrigeration cycle device 1, which uses a refrigerant that may undergo a disproportionation reaction, can be ensured.

[0081] Furthermore, by suppressing the pressure rise during the disproportionation reaction in compressor 21, it is also possible to suppress the rapid pressure rise in the first refrigerant pipe 11, four-way switching valve 22, second refrigerant pipe 12, outdoor heat exchanger 23, third refrigerant pipe 13, expansion valve 24, fifth refrigerant pipe 15, gas-side refrigerant connecting pipe 5, ninth refrigerant pipe 19, indoor heat exchanger 31, eighth refrigerant pipe 18, liquid-side refrigerant connecting pipe 6, and fourth refrigerant pipe 14 connected to the discharge side of compressor 21. This improves the reliability of these pipes and components. Additionally, pipes and components with low pressure resistance can also be used as these pipes and components.

[0082] (9) Its implementation method

[0083] (9-1) Other implementation methods A

[0084] In the above embodiment, a refrigerant circuit 10, whose total internal volume of the first refrigerant piping 11, the four-way switching valve 22, the second refrigerant piping 12, the outdoor heat exchanger 23, the third refrigerant piping 13, and the expansion valve 24 connected to the discharge side of the compressor 21 is described as an example, and is at least 0.7 times the internal volume of the compressor 21.

[0085] In contrast, for example, the refrigerant circuit 10 may be configured such that the total internal volume of the first refrigerant piping 11, the four-way switching valve 22, the second refrigerant piping 12, and the outdoor heat exchanger 23 connected to the discharge side of the compressor 21 is more than 0.7 times the internal volume of the compressor 21.

[0086] (9-2) Other implementation methods B

[0087] In the above embodiment, a refrigerant circuit 10, whose total internal volume of the first refrigerant pipe 11, four-way switching valve 22, fifth refrigerant pipe 15, gas-side refrigerant connecting pipe 5, ninth refrigerant pipe 19, indoor heat exchanger 31, eighth refrigerant pipe 18, liquid-side refrigerant connecting pipe 6, fourth refrigerant pipe 14, and expansion valve 24 connected to the discharge side of compressor 21 is described as being at least 0.7 times the internal volume of compressor 21.

[0088] In contrast, for example, the refrigerant circuit 10 may be configured such that the total internal volume of the first refrigerant pipe 11, the four-way switching valve 22, the fifth refrigerant pipe 15, the gas-side refrigerant connecting pipe 5, the ninth refrigerant pipe 19, and the indoor heat exchanger 31 connected to the discharge side of the compressor 21 is more than 0.7 times the internal volume of the compressor 21.

[0089] (9-3) Other implementation methods C

[0090] In the above embodiment, a refrigerant circuit 10 is described as an example, in which the total internal volume of the refrigerant piping, heat exchanger, etc., connected to the discharge side of the compressor 21 is more than 0.7 times the internal volume of the compressor 21.

[0091] In contrast, for example, the refrigerant circuit 10 may be configured such that the total internal volume of the refrigerant piping, heat exchanger, etc. connected to the suction side of the compressor 21 is more than 0.7 times the internal volume of the compressor 21.

[0092] Specifically, the refrigerant circuit 10 can also be configured as follows: When the refrigerant circuit 10 is in a refrigeration connection state, the total volume of the 7th refrigerant pipe 17, receiver 41, 6th refrigerant pipe 16, four-way switching valve 22, 5th refrigerant pipe 15, gas-side refrigerant connecting pipe 5, 9th refrigerant pipe 19, indoor heat exchanger 31, 8th refrigerant pipe 18, liquid-side refrigerant connecting pipe 6, 4th refrigerant pipe 14, and expansion valve 24 is not more than 0.7 times the internal volume of compressor 21; when the refrigerant circuit 10 is in a heating connection state, the total volume of the 7th refrigerant pipe 17, receiver 41, 6th refrigerant pipe 16, four-way switching valve 22, 2nd refrigerant pipe 12, outdoor heat exchanger 23, 3rd refrigerant pipe 13, and expansion valve 24 is more than 0.7 times the internal volume of compressor 21.

[0093] Alternatively, the refrigerant circuit 10 may be a refrigerant circuit whose internal volume, including the refrigerant piping and heat exchanger connected to the discharge side of the compressor 21, and the internal volume of the refrigerant piping and heat exchanger connected to the suction side of the compressor 21, together ensure that the internal volume of the compressor 21 is at least 0.7 times that of the compressor 21.

[0094] (9-4) Other implementation methods D

[0095] In the above embodiment, a refrigerant circuit 10 is described as an example, in which the total internal volume of the refrigerant piping, heat exchanger, etc., connected to the discharge side of the compressor 21 is more than 0.7 times the internal volume of the compressor 21.

[0096] In contrast, to easily and reliably ensure the total volume of the refrigerant piping, heat exchanger, etc., connected to the discharge side of compressor 21, one or more refrigerant containers, such as receivers, may be provided on the discharge side of compressor 21. For example, a refrigerant circuit 10 may be provided with a refrigerant container along the path from the discharge side of compressor 21 to expansion valve 24.

[0097] Furthermore, in order to easily and maximally ensure the total internal volume of the refrigerant piping, heat exchanger, etc., connected to the suction side of the compressor 21, one or more refrigerant containers, such as receivers, may be provided on the suction side of the compressor 21. For example, a refrigerant circuit 10 may be provided with a refrigerant container along the path from the suction side of the compressor 21 to the expansion valve 24.

[0098] (9-5) Other implementation methods E

[0099] In the above embodiments, the example described is that the refrigeration cycle device 1 has a refrigerant circuit 10 that can switch between refrigeration operation and heating operation.

[0100] In contrast, the refrigeration cycle device 1 may also have a refrigerant circuit dedicated to refrigeration operation.

[0101] (Postscript)

[0102] The embodiments of the present invention have been described above. However, it should be understood that various changes can be made to the methods and details without departing from the spirit and scope of the present invention as set forth in the claims.

[0103] Symbol Explanation

[0104] 1. Refrigeration cycle unit; 5. Gas-side refrigerant connection piping (refrigerant piping)

[0105] 6. Liquid-side refrigerant connection piping (refrigerant piping)

[0106] 10 Refrigerant Circuit

[0107] 10a Refrigerant Circuit 11 First Refrigerant Piping (Refrigerant Piping)

[0108] 12. Second refrigerant piping (refrigerant piping)

[0109] 13. Third refrigerant piping (refrigerant piping)

[0110] 14. Fourth refrigerant piping (refrigerant piping)

[0111] 15. Fifth refrigerant piping (refrigerant piping)

[0112] 18. Refrigerant piping for the 8th refrigerant section (refrigerant piping)

[0113] 19.9 Refrigerant Piping (Refrigerant Piping)

[0114] 21 compressor

[0115] 23 Outdoor heat exchanger (component)

[0116] 24 Expansion Valve (Component)

[0117] 31 Indoor heat exchanger (component)

[0118] 41. Receiver (component)

[0119] Existing technical documents

[0120] Patent documents

[0121] Patent Document 1: Japanese Patent Application Publication No. 2019-196312

Claims

1. Use of a composition as a refrigerant in a refrigerant circuit (10), the composition comprising one or more of a group selected from the group consisting of ethylene-based fluoroolefins, 2,3,3,3-tetrafluoropropylene (HFO-1234yf) and 1,3,3,3-tetrafluoropropylene (HFO-1234ze), wherein the internal volume of the refrigerant piping (11, 12, 13, 15, 5, 19, 18, 6, 14) and components (23, 31, 24, 41) connected to the compressor (21) in the refrigerant circuit (10) is at least 0.7 times the internal volume of the compressor. The refrigerant circuit includes the compressor (21), outdoor heat exchanger (23), indoor heat exchanger (31), and a four-way switching valve (22), which switches between states where refrigerant discharged from the compressor is sent to the outdoor heat exchanger and states where refrigerant discharged from the compressor is sent to the indoor heat exchanger. The internal volume of the space from the discharge side of the compressor through the four-way switching valve to the outdoor heat exchanger and the internal volume of the space from the discharge side of the compressor through the four-way switching valve to the indoor heat exchanger are both at least 0.7 times the internal volume of the compressor.

2. The use as described in claim 1, wherein, The composition comprises one or more of the following: 1,2-difluoroethylene (HFO-1132), 1,1-difluoroethylene (HFO-1132a), 1,1,2-trifluoroethylene (HFO-1123), monofluoroethylene (HFO-1141), trifluorochloroethylene (CFO-1113), and perfluoroolefins.

3. The use as described in claim 2, wherein, The composition comprises 1,2-difluoroethylene (HFO-1132) and / or 1,1,2-trifluoroethylene (HFO-1123).

4. The use as described in any one of claims 1 to 3, wherein, The refrigerant circuit includes the compressor (21), outdoor heat exchanger (23), indoor heat exchanger (31), and a four-way switching valve (22), which switches between states where refrigerant discharged from the compressor is sent to the outdoor heat exchanger and states where refrigerant discharged from the compressor is sent to the indoor heat exchanger. The internal volume of the space from the discharge side of the compressor through the four-way switching valve to the outdoor heat exchanger and the internal volume of the space from the discharge side of the compressor through the four-way switching valve to the indoor heat exchanger are both more than 5.0 times the internal volume of the compressor.

5. A refrigeration cycle device (1) that uses a composition of one or more of the following as a refrigerant: a fluoroolefin selected from the ethylene group, 2,3,3,3-tetrafluoropropylene (HFO-1234yf), and 1,3,3,3-tetrafluoropropylene (HFO-1234ze). It has a refrigerant circuit (10) with a compressor (21), refrigerant piping (11, 12, 13, 15, 5, 19, 18, 6, 14) and components (23, 31, 24, 41). The internal volume of the refrigerant piping and the component is at least 0.7 times the internal volume of the compressor. The refrigerant circuit includes the compressor (21), outdoor heat exchanger (23), indoor heat exchanger (31), and a four-way switching valve (22), which switches between states where refrigerant discharged from the compressor is sent to the outdoor heat exchanger and states where refrigerant discharged from the compressor is sent to the indoor heat exchanger. The internal volume of the space from the discharge side of the compressor through the four-way switching valve to the outdoor heat exchanger and the internal volume of the space from the discharge side of the compressor through the four-way switching valve to the indoor heat exchanger are both at least 0.7 times the internal volume of the compressor.

6. The refrigeration cycle apparatus as described in claim 5, wherein, The composition comprises 1,2-difluoroethylene (HFO-1132) and / or 1,1,2-trifluoroethylene (HFO-1123).

7. The refrigeration cycle apparatus as described in claim 5 or 6, wherein, The refrigerant circuit includes the compressor (21), outdoor heat exchanger (23), indoor heat exchanger (31), and a four-way switching valve (22), which switches between states where refrigerant discharged from the compressor is sent to the outdoor heat exchanger and states where refrigerant discharged from the compressor is sent to the indoor heat exchanger. The internal volume of the space from the discharge side of the compressor through the four-way switching valve to the outdoor heat exchanger and the internal volume of the space from the discharge side of the compressor through the four-way switching valve to the indoor heat exchanger are both more than 5.0 times the internal volume of the compressor.

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