Working medium for heat cycle, method for storing working medium for heat cycle, method for producing working medium for heat cycle, composition for heat cycle system, and container for storing working medium for heat cycle

Abstract

A working medium for a heat cycle, which contains trifluoroethylene, a low-boiling-point compound having a lower boiling point than trifluoroethylene, and a high-boiling-point compound having a higher boiling point than trifluoroethylene, and the use thereof, in which the low-boiling-point compound is at least one compound selected from the group consisting of carbon dioxide, R116, and R41. The high boiling point compound is composed of at least two kinds selected from the group consisting of HFC-32, HFO-1234yf, HFO-1234ze (E), HFO-1243zf, PFC-14, HFC-134, HFC-143a, HFC-227ea, cyclopropane, isobutane, and dimethyl ether.

Description

Technical Field

[0001] The present invention relates to a working medium for a thermal cycle, a method for storing the working medium for a thermal cycle, a method for manufacturing the working medium for a thermal cycle, a composition for a thermal cycle system, and a storage container for the working medium for a thermal cycle. Background Art

[0002] Conventionally, various studies have been conducted on working media for thermal cycles such as refrigerants for refrigerators, refrigerants for air conditioners, working media for power generation systems (such as waste heat recovery power generation), working media for latent heat transfer devices (such as heat pipes), and secondary cooling media.

[0003] In recent years, hydrofluoroolefins (HFOs), that is, HFCs having a carbon-carbon double bond, have been highly anticipated. The carbon-carbon double bond possessed by HFOs is easily decomposed by OH radicals in the atmosphere, so HFOs have little impact on the ozone layer and little impact on global warming. In the present disclosure, unless otherwise specified, saturated fluorohydrocarbons are referred to as HFCs and are used separately from HFOs.

[0004] For example, Patent Document 1 describes a working medium for a thermal cycle that contains trifluoroethylene and a first component composed of at least one substance selected from carbon dioxide, fluoromethane, trifluoroiodomethane, methane, ethane, propane, helium, neon, argon, krypton, xenon, nitrogen, and ammonia. Prior Art Documents Patent Documents

[0005] Patent Document 1: International Publication No. 2016 / 194837 Summary of the Invention Technical Problem to be Solved by the Invention

[0006] In an environment where a working medium for a thermal cycle is used, it is required to reduce the global warming potential, improve the cycle performance, and suppress the disproportionation reaction when using a compound that exhibits a disproportionation reaction. By suppressing the concentration of the compound that exhibits a disproportionation reaction in the gas phase, the disproportionation reaction during the product usage cycle can be suppressed not only under the operating conditions of equipment that may be under high temperature and high pressure but also during transportation, storage, and equipment shutdown.

[0007] The technical problem to be solved by one embodiment of the present disclosure is to provide a working medium for a thermal cycle, a method for storing the working medium for a thermal cycle, and a method for manufacturing the working medium for a thermal cycle, which have a low global warming potential, excellent cycle performance, and can suppress the concentration of trifluoroethylene in the gas phase. Another embodiment of the present disclosure aims to provide a composition for a thermal cycle system containing the above-mentioned working medium for a thermal cycle and a storage container for storing the above-mentioned working medium for a thermal cycle. Means for Solving the Technical Problem

[0008] The present invention includes the following aspects. <1> A working medium for thermal cycling, which comprises trifluoroethylene, a low-boiling compound having a boiling point lower than that of trifluoroethylene, and a high-boiling compound having a boiling point higher than that of trifluoroethylene, wherein the low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane, and the high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia. <2> The working medium for thermal cycling according to <1>, wherein the content of the trifluoroethylene is 30.0% by mass to 80.0% by mass relative to the total content of the trifluoroethylene, the low-boiling compound, and the high-boiling compound, the content of the low-boiling compound is 2.7% by mass to 60.0% by mass relative to the total content, the content of the high-boiling compound is 10.0% by mass to 67.3% by mass relative to the total content, and the total content of the trifluoroethylene, the low-boiling compound, and the high-boiling compound is 90.0% by mass or more relative to the total amount of the working medium for thermal cycling. <3> The working medium for thermal cycling according to <1>, wherein the low-boiling compound contains carbon dioxide, the high-boiling compound contains difluoromethane and 2,3,3,3-tetrafluoropropene, when the content of the trifluoroethylene is set as A% by mass relative to the total content of the trifluoroethylene, the carbon dioxide, the difluoromethane, and the 2,3,3,3-tetrafluoropropene, the content of the carbon dioxide is set as B% by mass relative to the total content, the content of the difluoromethane is set as C% by mass relative to the total content, and the content of the 2,3,3,3-tetrafluoropropene is set as D% by mass relative to the total content, A is 30.0 to 80.0, B is 2.7 to 60.0, C is 5.0 to 45.0, D is 5.0 to 62.3. <4> The working medium for thermal cycling according to <3>, wherein A is 30.0 to 80.0, B is 2.7 to 15.0, C is 5.0 to 45.0, D satisfies the following formula (1) 5.0 ≤ D ≤ (0.000003B 2 −0.00053B + 0.00616) × A 2 +(−0.00013B 2 + 0.07589B − 1.09581) × A + (0.05608 × B 2 − 5.19457B + 79.27652). <5> The working medium for thermal cycling as described in <1>, wherein, The low-boiling compound contains carbon dioxide, The high-boiling compound contains difluoromethane and (E)-1,3,3,3-tetrafluoropropene When the content of the trifluoroethylene is set to E mass% with respect to the total content of the trifluoroethylene, the carbon dioxide, the difluoromethane and the (E)-1,3,3,3-tetrafluoropropene, the content of the carbon dioxide is set to F mass% with respect to the total content, the content of the difluoromethane is set to G mass% with respect to the total content, and the content of the (E)-1,3,3,3-tetrafluoropropene is set to H mass% with respect to the total content, E is 30.0 to 80.0, F is 3.0 to 60.0, G is 5.0 to 45.0, H is 5.0 to 62.0. <6> The working medium for thermal cycling as described in <5>, wherein, E is 30.0 to 80.0, F is 3.0 to 15.0, G is 5.0 to 45.0, H satisfies the following formula (2) 5.0 ≤ H ≤ (0.000005F 2 −0.00037F + 0.00301) × E 2 +(−0.00087F 2 + 0.05802F − 0.54609)E + (0.05969F 2 − 3.39263F + 41.55565). <7> A composition for a thermal cycle system, which comprises a working medium for thermal cycle as described in any one of <1> to <6> and a refrigeration oil. <8> The composition for a thermal cycle system as described in <7>, wherein the refrigeration oil is at least one selected from polyalkylene glycol oils, polyol ester oils, polyethylene ether oils, fluorinated oils, mineral oils, and hydrocarbon synthetic oils. <9> A method for storing a working medium for thermal cycle, which includes a step of storing a working medium for thermal cycle containing trifluoroethylene, a low-boiling compound having a boiling point lower than that of the trifluoroethylene, and a high-boiling compound having a boiling point higher than that of the trifluoroethylene. The low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane. The high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia. <10> A method for manufacturing a working medium for thermal cycle, which includes a step of mixing trifluoroethylene, a low-boiling compound having a boiling point lower than that of the trifluoroethylene, and a high-boiling compound having a boiling point higher than that of the trifluoroethylene. The low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane. The high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia. <11> A storage container for a working medium for thermal cycle, which is a closed storage container for storing a working medium for thermal cycle containing trifluoroethylene, a low-boiling compound having a boiling point lower than that of the trifluoroethylene, and a high-boiling compound having a boiling point higher than that of the trifluoroethylene in a state where the gas phase and the liquid phase coexist. The low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane. The high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia. Advantages of the Invention

[0009] According to an embodiment of the present disclosure, there is provided a working medium for a thermal cycle, a storage method for the working medium for a thermal cycle, and a manufacturing method for the working medium for a thermal cycle, which have a low global warming potential, excellent cycle performance, and can suppress the concentration of trifluoroethylene in the gas phase. According to another embodiment of the present disclosure, there is provided a composition for a thermal cycle system containing the above-mentioned working medium for a thermal cycle, and a storage container for storing the above-mentioned working medium for a thermal cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic structural diagram showing a refrigeration cycle system as an example of a thermal cycle system. Figure 2 is a cycle diagram depicting the state change of the working medium in the refrigeration cycle system on a pressure-enthalpy curve graph. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the present disclosure, the numerical range represented by "~" includes the range with the values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described hierarchically in the present disclosure, the upper limit value or the lower limit value described in one numerical range can be replaced with the upper limit value or the lower limit value of other hierarchically described numerical ranges. In addition, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range can also be replaced with the value shown in the examples. In the present disclosure, the combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, when there are multiple substances corresponding to each component, unless otherwise specified, the amount of each component refers to the total amount of the multiple substances. In the present disclosure, the boiling point refers to the boiling point at atmospheric pressure (101.325 kPa).

[0012] [Working Medium for Thermal Cycle] The working medium for thermal cycling of the present invention (hereinafter also referred to as "working medium") comprises trifluoroethylene (HFO-1123), a low-boiling compound having a boiling point lower than that of HFO-1123, and a high-boiling compound having a boiling point higher than that of HFO-1123. The low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane (R116), and fluoromethane (R41), and the high-boiling compound is at least two selected from difluoromethane (HFC-32), 2,3,3,3-tetrafluoropropene (HFO-1234yf), (E)-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), 3,3,3-trifluoropropene (HFO-1243zf), tetrafluoromethane (PFC-14), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1-trifluoroethane (HFC-143a), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

[0013] In the present disclosure, a compound having a boiling point lower than that of trifluoroethylene is also simply referred to as a "low-boiling compound", and a compound having a boiling point higher than that of trifluoroethylene is also simply referred to as a "high-boiling compound". In addition, when there is no liquid in the properties of the compound, the boiling point is replaced by the sublimation point.

[0014] In the present disclosure, the working medium refers to a medium for heat transfer and is a concept including a refrigerant composition and a heating agent composition. Among them, the refrigerant composition is a medium mainly for cooling the heat source, but can also be used as a medium for heating at the same time. The heating agent composition is a medium mainly for heating, but can also be used as a medium for cooling the heat source at the same time. The working medium of the present disclosure is used for thermal cycling. Specifically, the working medium of the present disclosure is preferably used in a thermal cycling system that generates a series of changes that utilize heat absorption and heat dissipation to implement a state change and then return to the initial state again.

[0015] The working medium of the present disclosure has excellent cycling performance and can suppress the concentration of HFO-1123 in the gas phase. The reason is not yet certain, but it is speculated as follows.

[0016] It is known that HFO-1123 undergoes a disproportionation reaction in the gas phase when the temperature, pressure, and ignition source reach specific thresholds. The disproportionation reaction refers to a self-decomposition reaction that usually generates heat. On the other hand, as compounds that do not exhibit disproportionation reactions and exhibit high environmental performance, HFOs such as HFO-1234yf and HFO-1234ze(E) are known. In the past, as a method for suppressing the disproportionation reaction of HFO-1123, a method of mixing HFO-1123 with a compound that does not exhibit a disproportionation reaction has been proposed. However, the boiling points of HFO-1234yf and HFO-1234ze(E) are higher than that of HFO-1123. Therefore, when storing a working medium containing HFO-1123 and a compound with a boiling point higher than that of HFO-1123 in a closed container, due to the gas-liquid equilibrium, HFO-1123 will move from the liquid phase to the gas phase, and the concentration of HFO-1123 in the gas phase tends to increase compared to the concentration of HFO-1123 in the liquid phase. Therefore, even if a working medium is prepared with a composition that does not cause the disproportionation reaction of HFO-1123, due to the gas-liquid equilibrium, the concentration of HFO-1123 in the gas phase increases, and sometimes it may become a composition in which the disproportionation reaction of HFO-1123 can occur. Therefore, the present inventors focused on the increase in the concentration of HFO-1123 in the gas phase (concentration of HFO-1123), and in order to suppress the disproportionation reaction of HFO-1123, studied a method for suppressing the concentration of HFO-1123 in the gas phase.

[0017] As a result, it was found that by mixing at least one low-boiling compound selected from carbon dioxide, R116, and R41 in addition to HFO-1123, the concentration of HFO-1123 in the gas phase can be suppressed. Moreover, it was found that by mixing at least two high-boiling compounds selected from HFC-32, HFO-1234yf, HFO-1234ze(E), HFO-1243zf, PFC-14, HFC-134, HFC-143a, HFC-227ea, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia in addition to at least one low-boiling compound selected from carbon dioxide, R116, and R41, excellent cycle performance can be obtained while suppressing the concentration of HFO-1123 in the gas phase.

[0018] In contrast, the examples in Patent Document 1 only describe working media containing a first component such as HFO-1123 and carbon dioxide and a second component such as HFC-32, and do not substantially describe a working medium containing at least two high-boiling compounds. Moreover, Patent Document 1 does not focus on the concentration of HFO-1123 in the gas phase.

[0019] Hereinafter, each component contained in the working medium of the present disclosure will be described in detail.

[0020] The working medium of the present disclosure contains HFO-1123, a low-boiling compound, and a high-boiling compound.

[0021] In the working medium of the present disclosure, the total content of HFO-1123, the low-boiling compound, and the high-boiling compound is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, and still more preferably 99.0% by mass or more, relative to the total amount of the working medium. The upper limit of the total content of HFO-1123, the low-boiling compound, and the high-boiling compound is not particularly limited and may be 100% by mass.

[0022] <HFO-1123> The working medium of the present disclosure contains HFO-1123. HFO-1123 has the characteristics of high refrigeration cycle performance, low global warming potential (GWP), and low flammability. The boiling point of HFO-1123 is -61.239 °C at atmospheric pressure.

[0023] From the viewpoints of pressure and critical temperature, the content of HFO-1123 is preferably 80.0% by mass or less, more preferably 70.0% by mass or less, and still more preferably 60.0% by mass or less, relative to the total content of HFO-1123, the low-boiling compound, and the high-boiling compound. In addition, from the viewpoints of reducing GWP and enhancing the capacity per unit volume, the content of HFO-1123 is preferably 30.0% by mass or more, more preferably 35.0% by mass or more, and still more preferably 40.0% by mass or more, relative to the total content of HFO-1123, the low-boiling compound, and the high-boiling compound.

[0024] <Low-boiling compound> The working medium of the present disclosure contains a low-boiling compound having a boiling point lower than that of HFO-1123. The low-boiling compound is at least one selected from carbon dioxide, R116, and R41. The low-boiling compound may be one kind or two or more kinds.

[0025] Carbon dioxide, R116, and R41 are all compounds that do not exhibit disproportionation reactions.

[0026] Since the boiling point of the above-mentioned low-boiling compound is lower than that of HFO-1123, it is easier to move into the gas phase than HFO-1123. Therefore, by including the above-mentioned low-boiling compound in the working medium of the present disclosure, the concentration of HFO-1123 in the gas phase can be suppressed.

[0027] From the viewpoints of pressure and critical temperature, the content of the low-boiling compound is preferably 60.0% by mass or less, more preferably 15.0% by mass or less, still more preferably 12.0% by mass or less, and particularly preferably 10.0% by mass or less, based on the total content of HFO-1123, the low-boiling compound, and the high-boiling compound. In addition, from the viewpoint of further enhancing the effect of suppressing the concentration of HFO-1123 in the gas phase, the content of the low-boiling compound is preferably 2.7% by mass or more, more preferably 3.0% by mass or more, still more preferably 3.5% by mass or more, based on the total content of HFO-1123, the low-boiling compound, and the high-boiling compound. In the case where two or more low-boiling compounds are included, the content of the low-boiling compound means the total content of the two or more low-boiling compounds.

[0028] Among them, the low-boiling compound is preferably at least one selected from carbon dioxide and R41, and more preferably carbon dioxide.

[0029] Carbon dioxide has a tendency to have lower compatibility with refrigeration oils (such as polyalkylene glycol oils, polyol ester oils, polyethylene ether oils, etc.) compared with HFCs and HFOs. Therefore, when the working medium containing HFO-1123 and carbon dioxide coexists with the refrigeration oil in a closed container, carbon dioxide is more likely to concentrate in the gas phase than HFO-1123. The concentration of carbon dioxide in the gas phase inhibits the concentration of HFO-1123 in the gas phase.

[0030] In addition, carbon dioxide has characteristics of high refrigeration cycle performance, excellent heat transfer performance, and non-flammability.

[0031] When the working medium of the present disclosure contains carbon dioxide, from the viewpoints of pressure and critical temperature, the content of carbon dioxide is preferably 60.0% by mass or less, more preferably 15.0% by mass or less, still more preferably 12.0% by mass or less, and particularly preferably 10.0% by mass or less, based on the total content of HFO-1123, the low-boiling compound, and the high-boiling compound. In addition, from the viewpoint of further enhancing the effect of suppressing the concentration of HFO-1123 in the gas phase, the content of carbon dioxide is preferably 2.7% by mass or more, more preferably 3.0% by mass or more, still more preferably 3.5% by mass or more, based on the total content of HFO-1123, the low-boiling compound, and the high-boiling compound.

[0032] <High-boiling compound> The working medium of the present disclosure contains high-boiling compounds with a boiling point higher than that of HFO-1123. The high-boiling compounds are at least two selected from HFC-32, HFO-1234yf, HFO-1234ze(E), HFO-1243zf, PFC-14, HFC-134, HFC-143a, HFC-227ea, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia. The high-boiling compounds can be two or more than three.

[0033] It is difficult to reduce the GWP and improve the cycle performance (such as volumetric capacity, COP, temperature gradient, pressure, etc.) by using only one of the above high-boiling compounds. Since the working medium of the present disclosure contains two or more high-boiling compounds, it can improve the cycle performance with good balance.

[0034] HFC-32, HFO-1234yf, HFO-1234ze(E), HFO-1243zf, PFC-14, HFC-134, HFC-143a, HFC-227ea, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia are all compounds that do not exhibit disproportionation reactions.

[0035] As a combination of two high-boiling compounds, the following combinations are preferred. ·HFC-32, HFO-1234yf ·HFC-32, HFO-1234ze(E) ·HFC-32, HFO-1243zf ·HFC-32, cyclopropane ·HFO-1234yf, cyclopropane ·HFO-1234ze(E), cyclopropane ·HFO-1234yf, HFO-1234ze(E) ·HFO-1234yf, HFO-1243zf ·dimethyl ether, HFO-1234ze(E)

[0036] The content of the high-boiling compounds is preferably 67.3% by mass or less, more preferably 50.0% by mass or less, and further preferably 40.0% by mass or less. In addition, the content of the high-boiling compounds is preferably 10.0% by mass or more, more preferably 15.0% by mass or more, and further preferably 20.0% by mass or more. Herein, the content of the high-boiling compounds refers to the total content of two or more high-boiling compounds.

[0037] Among them, the high-boiling compound is preferably selected from at least one of HFC-32, HFO-1234yf, HFO-1234ze(E), and dimethyl ether, and more preferably selected from at least one of HFC-32, HFO-1234yf, and HFO-1234ze(E).

[0038] HFC-32 has the characteristics of high refrigeration cycle performance, high azeotropy with HFO-1123, and low flammability.

[0039] When the working medium of the present disclosure contains HFC-32, from the perspective of reducing GWP, the content of HFC-32 is preferably 45.0% by mass or less, more preferably 40.0% by mass or less, and further preferably 35% by mass. In addition, from the perspective of enhancing the capacity per unit volume and the azeotropy with HFO-1123, it is preferably 5.0% by mass or more, more preferably 7.0% by mass or more, and further preferably 10.0% by mass or more.

[0040] HFO-1234yf has the effects of low GWP, low flammability, and reducing pressure by mixing with HFO-1123.

[0041] When the working medium of the present disclosure contains HFO-1234yf, from the perspective of improving the coefficient of performance (COP) and the azeotropy with HFO-1123, the content of HFO-1234yf is preferably 62.3% by mass or less, more preferably 50.0% by mass or less, and further preferably 40.0% by mass or less. In addition, from the perspective of reducing GWP, the content of HFO-1234yf is preferably 5.0% by mass or more, more preferably 7.0% by mass or more, and further preferably 10.0% by mass or more.

[0042] HFO-1234ze(E) has the effects of low GWP, low flammability, and reducing pressure by mixing with HFO-1123.

[0043] When the working medium of the present disclosure contains HFO-1234ze(E), from the perspective of improving the coefficient of performance (COP) and the azeotropy with HFO-1123, the content of HFO-1234ze(E) is preferably 62.0% by mass or less, more preferably 50.0% by mass or less, and further preferably 40.0% by mass or less. In addition, from the perspective of reducing GWP, the content of HFO-1234ze(E) is preferably 5.0% by mass or more, more preferably 7.0% by mass or more, and further preferably 10.0% by mass or more.

[0044] Among them, in the working medium of the present disclosure, preferably, the content of HFO-1123 is 30.0% to 80.0% by mass relative to the total content of HFO-1123, low-boiling compounds, and high-boiling compounds, the content of low-boiling compounds is 2.7% to 60.0% by mass relative to the above total content, the content of high-boiling compounds is 10.0% to 67.3% by mass relative to the above total content, and the total content of HFO-1123, low-boiling compounds, and high-boiling compounds is 90.0% by mass or more relative to the total amount of the working medium. The preferred content of each of HFO-1123, low-boiling compounds, and high-boiling compounds is as described above.

[0045] From the viewpoint of further increasing the critical temperature, the content of low-boiling compounds is preferably 40.0% by mass or less, more preferably 20.0% by mass or less.

[0046] The total content of HFO-1123, low-boiling compounds, and high-boiling compounds is more preferably 95.0% by mass relative to the total amount of the working medium, and further preferably 99.0% by mass or more. The upper limit value of the above total content is not particularly limited and may be 100% by mass.

[0047] Hereinafter, a more preferred composition of the working medium of the present disclosure will be described.

[0048] (First mode) In the first mode of the working medium of the present disclosure, preferably, the low-boiling compound contains carbon dioxide, the high-boiling compound contains HFC-32 and HFO-1234yf, and the content of HFO-1123 is set as A% by mass relative to the total content of HFO-1123, carbon dioxide, HFC-32, and HFO-1234yf, the content of carbon dioxide is set as B% by mass relative to the above total content, the content of HFC-32 is set as C% by mass relative to the above total content, and the content of HFO-1234yf is set as C% by mass relative to the above total content. When the content of HFO-1234yf is set as HFO-1234yf relative to the above total content, A is 30.0 to 80.0, B is 2.7 to 60.0, C is 5.0 to 45.0, and D is 5.0 to 62.3.

[0049] When A is 30.0 or more, the GWP is reduced and the capacity per unit volume is increased. When A is 80.0 or less, the pressure is reduced and the critical temperature is increased.

[0050] When B is 2.7 or more, the effect of suppressing the concentration of HFO-1123 in the gas phase is high. When B is 60.0 or less, the critical temperature is increased. From the viewpoint of further increasing the critical temperature, B is preferably 40.0 or less, more preferably 20.0 or less.

[0051] When C is above 5.0, the capacity per unit volume increases and the azeotropy with HFO-1123 improves. When C is below 45.0, the GWP decreases.

[0052] When D is above 5.0, the GWP decreases. When D is below 62.3, the capacity per unit volume increases and the azeotropy with HFO-1123 improves.

[0053] The more preferred contents of HFO-1123, carbon dioxide, HFC-32, and HFO-1234yf are as described above.

[0054] In the first mode, the content of carbon dioxide is preferably 90.0 mass% or more, more preferably 95.0 mass% or more, and preferably 99.0 mass% or more relative to the total amount of the low-boiling compounds. The upper limit value of the content of carbon dioxide is not particularly limited and may be 100 mass%. That is, in the first mode, the low-boiling compound may be carbon dioxide.

[0055] In the first mode, the contents of HFC-32 and HFO-1234yf are preferably 90.0 mass% or more, more preferably 95.0 mass% or more, and preferably 99.0 mass% or more relative to the total amount of the high-boiling compounds. The upper limit value of the contents of HFC-32 and HFO-1234yf is not particularly limited and may be 100 mass%. That is, in the first mode, the high-boiling compounds may be HFC-32 and HFO-1234yf.

[0056] In the first mode, it is preferred that A is 30.0 to 80.0, B is 2.7 to 15.0, C is 5.0 to 45.0, and D satisfies the following formula (1) 5.0 ≤ D ≤ (0.000003B 2 −0.00053B + 0.00616) × A 2 +(−0.00013B 2 + 0.07589B − 1.09581) × A + (0.05608 × B 2 − 5.19457B + 79.27652).

[0057] When A is 30.0 to 80.0, B is 2.7 to 15.0, C is 5.0 to 45.0, and D satisfies formula (1), the temperature gradient becomes smaller, and a temperature gradient of 7.0 °C or less can be achieved.

[0058] (Second mode) In the second mode of the working medium of the present invention, preferably, the low-boiling compound contains carbon dioxide, the high-boiling compound contains HFC-32 and HFO-1234ze(E), when the content of HFO-1123 is set to E mass% relative to the total content of HFO-1123, carbon dioxide, HFC-32 and HFO-1234ze(E), the content of carbon dioxide is set to F mass% relative to the above total content, the content of HFC-32 is set to G mass% relative to the above total content, and the content of HFO-1234ze(E) is set to H% relative to the above total content, E is 30.0 to 80.0, F is 3.0 to 60.0, G is 5.0 to 45.0, and H is 5.0 to 62.0.

[0059] When E is 30.0 or more, the GWP decreases and the capacity per unit volume increases. When E is 80.0 or less, the pressure decreases and the critical temperature increases.

[0060] When F is 3.0 or more, the effect of suppressing the concentration of HFO-1123 in the gas phase is high. When F is 60.0 or less, the critical temperature increases. From the viewpoint of further increasing the critical temperature, F is preferably 40.0 or less, more preferably 20.0 or less.

[0061] When G is 5.0 or more, the capacity per unit volume increases and the azeotropy with HFO-1123 improves. When G is 45.0 or less, the GWP decreases.

[0062] When H is 5.0 or more, the GWP decreases. When H is 62.0 or less, the capacity per unit volume increases and the azeotropy with HFO-1123 improves.

[0063] The more preferred contents of HFO-1123, carbon dioxide, HFC-32 and HFO-1234ze(E) are as described above.

[0064] In the second mode, the content of carbon dioxide relative to the total amount of the low-boiling compounds is preferably 90.0 mass% or more, more preferably 95.0 mass% or more, preferably 99.0 mass% or more. The upper limit value of the content of carbon dioxide is not particularly limited and may be 100 mass%. That is, in the second mode, the low-boiling compound may be carbon dioxide.

[0065] In the second mode, the content of HFC-32 and HFO-1234ze(E) relative to the total amount of the high-boiling compounds is preferably 90.0 mass% or more, more preferably 95.0 mass% or more, preferably 99.0 mass% or more. The upper limit value of the content of HFC-32 and HFO-1234ze(E) is not particularly limited and may be 100 mass%. That is, in the second mode, the high-boiling compound may be HFC-32 and HFO-1234ze(E).

[0066] In the second method, preferably, E is 30.0 to 80.0, F is 3.0 to 15.0, G is 5.0 to 45.0, and H satisfies the following formula (2). 5.0 ≤ H ≤ (0.000005F 2 −0.00037F + 0.00301)×E 2 +(−0.00087F 2 + 0.05802F − 0.54609)E+(0.05969F 2 − 3.39263F + 41.55565).

[0067] When E is 30.0 to 80.0, F is 3.0 to 15.0, G is 5.0 to 45.0, and H satisfies formula (2), the temperature gradient becomes smaller, and a temperature gradient of 7.0°C or less can be achieved.

[0068] In addition to HFO-1123, the above-mentioned low-boiling-point compound, and the above-mentioned high-boiling-point compound, the working medium of the present disclosure may further contain compounds commonly used in working media as optional components. As optional components, for example, HFCs, HFOs, CFOs, HCFOs, halogenated compounds containing iodine and bromine, and hydrocarbons other than HFO-1123, the low-boiling-point compound, and the high-boiling-point compound can be cited. In addition, the optional component may also be a compound that vaporizes and liquefies together with HFO-1123. The optional component may be only one kind or two or more kinds. In the present disclosure, the "halogenated compound" refers to an organic compound having a halogen atom.

[0069] As the optional component of HFC, 1,1-difluoroethane (HFC-152a), pentafluoropropane, hexafluoropropane, pentafluorobutane, and heptafluorocyclopentane can be cited. As the optional component of HFO, 1,1-difluoroethylene (HFO-1132a), (Z)-1,2-difluoroethylene (HFO-1132(Z)), (E)-1,2-difluoroethylene (HFO-1132(E)), 2-fluoropropene (HFO-1261yf), 1,1,2-trifluoropropene (HFO-1243yc), 1,2,3,3,3-pentafluoropropene (HFO-1225ye), and 3,3,3-trifluoropropene (HFO-1243zf) can be cited.

[0070] As the optional component of CFO, 1,1-dichloro-2,3,3-tetrafluoropropene (CFO-1214ya), 1,3-dichloro-1,2,3,3-tetrafluoropropene (CFO-1214yb), and 1,2-dichloro-1,2-difluoroethylene (CFO-1112) can be cited. As an optional component, HCFOs include, for example, 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) and 1-chloro-1,2-difluoroethylene (HCFO-1122). As an optional component, iodine- and bromine-containing halogenated compounds include, for example, methyl iodide (CH 3 I), methylene iodide (CH 2 I 2 ), methylene bromide (CH 2 Br 2 ), methyl bromide (CH 3 Br), methylene chloride (CH 2 Cl 2 ), chloroiodomethane (CH 2 ClI), bromodichloromethane (CHBr 2 Cl), carbon tetraiodide (CI 4 ), carbon tetrabromide (CBr 4 ), bromotrichloromethane (CBrCl 3 ), dibromodichloromethane (CBr 2 Cl 2 ), tribromofluoromethane (CBr 3 F), fluoroiodomethane (CHFI 2 ), difluoroiodomethane (CHF 2 I), difluorodiiodomethane (CF 2 I 2 ), dibromodifluoromethane (CBr 2 F 2 ), trifluoroiodomethane (CF 3 I) and 1,1,1-trifluoro-2-iodoethane (CF 3 CH 2 I). As an optional component, hydrocarbons include, for example, propylene, butane, pentane and isopentane.

[0071] When the working medium of the present disclosure contains an optional component, the content of the optional component is preferably less than 10.0% by mass, more preferably 8.0% by mass or less, and still more preferably 5.0% by mass or less, relative to the total amount of the working medium.

[0072] The water content in the working medium is preferably 20 mass ppm or less, particularly preferably 15 mass ppm or less, as the water content measured by the Karl Fischer coulometric titration method, relative to the total amount of the working medium. When the water content is 20 mass ppm or less, freezing in a capillary tube, etc., which is an example of a decompression device in a thermal cycle system, hydrolysis of the working medium or refrigeration oil, material deterioration caused by acid components generated in the device, occurrence of contamination, etc. can be suppressed.

[0073] The air content in the working medium, as the air concentration measured by gas chromatography, is preferably less than 15,000 mass ppm, and particularly preferably 8,000 mass ppm or less. When the air content is less than 15,000 mass ppm, poor heat transfer in the condenser and evaporator and the increase in the working pressure are suppressed. In particular, the reaction and decomposition of oxygen in the air with the working medium or the refrigerating oil are suppressed.

[0074] The working medium may contain impurities generated as by-products during manufacturing, such as specific components, and inevitable components such as solvents used in manufacturing. From the viewpoint of ensuring stability, the total content of these inevitable components is preferably 1.0 mass% or less, more preferably 0.5 mass% or less, and still more preferably 0.1 mass% or less, relative to the total amount of the working medium. From the viewpoint of simplifying the refining process during manufacturing of specific components, etc., the total content of inevitable components may be 50.0 mass ppm or more, or may be 100.0 mass ppm or more.

[0075] As inevitable components, examples include hydrogen fluoride, methane, chloromethane, dichlorodifluoromethane (CFC-12), 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113), chlorodifluoromethane (HCFC-22), chlorofluoromethane (HCFC-31), dichlorotrifluoroethane (HCFC-123), 1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a), 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124), 1-chloro-1,1,2,2-tetrafluoroethane (HCFC-124a), chlorotrifluoroethane (HCFC-133), 2-chloro-1,1,1-trifluoroethane (HCFC-133a), 1-chloro-1,1,2-trifluoroethane (HCFC-133b), 2-chloro-1,1-difluoroethane (HCFC-142), 1-chloro-1,1-difluoroethane (HCFC-142b), trifluoromethane (HFC-23), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,2-trifluoroethane (HFC143), 1,1,1-trifluoroethane (HFC-143a), 1,1-difluoroethane (HFC-152a), 1,1,1,2,2,3,3-heptafluoropropane (HFC-227ca), 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), 1,1-difluoroethylene (HFO-1132a), (E)-1,2-difluoroethylene (HFO-1132(E)), (Z)-1,2-difluoroethylene (HFO-1132(Z)), fluoroethylene (HFO-1141), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), (Z)-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 3,3,3-trifluoropropene (HFO-1243zf), 3,3-difluoropropene (HFO-1252zf), 1-chloro-2,2-difluoroethylene (HCFO-1122), (E)-1-chloro-1,2-difluoroethylene, (Z)-1-chloro-1,2-difluoroethylene, (E)-1-chloro-2-fluoroethylene (HCFO-1131(E)), (Z)-1-chloro-2-fluoroethylene (HCFO-1131(Z)), (E)-1,2-dichloro-1,2-difluoroethylene (CFO-1112(E)), (Z)-1,2-dichloro-1,2-difluoroethylene (CFO-1112(Z)), chlorotrifluoroethylene (CFO-113), tetrafluoroethylene (CFO-1114), hexafluoropropene (CFO-1216), perfluorocyclobutane, etc.

[0076] <Cycle performance> The characteristics required when the working medium is applied to a heat cycle system, i.e., the cycle performance, can be evaluated by the coefficient of performance (also referred to as "COP" in this disclosure) and the capacity per unit volume (the suction volume of the compressor) (also referred to as "CAP" in this disclosure). When the heat cycle system is a refrigeration cycle system, the capacity is the refrigeration capacity. As evaluation items when the working medium is applied to a refrigeration cycle system, in addition to the above cycle performance, the temperature gradient of the evaporator (also referred to as "temperature gradient" in this disclosure), the condensing pressure, the evaporating pressure, and the compression ratio can also be cited. Specifically, for the reference refrigeration cycle under the temperature conditions shown below, for example, each item is calculated by the method described later. For the condensing pressure, the evaporating pressure, and the compression ratio, the differential and relative values of CAP and COP are converted to the values based on R410A with the values of HFC-32 as the reference for evaluation.

[0077] (Temperature conditions of the reference refrigeration cycle) Evaporating temperature: 5 °C (however, in the case of azeotropic mixtures, it is the average temperature of the starting evaporation temperature and the ending evaporation temperature) Condensing temperature: 40 °C (however, in the case of azeotropic mixtures, it is the average temperature of the starting condensation temperature and the ending condensation temperature) Subcooling degree (SC): 5 °C Superheat degree (SH): 5 °C Compressor efficiency: 0.7

[0078] (Refrigeration cycle system) Hereinafter, a refrigeration cycle system as an example of a heat cycle system will be described. A refrigeration cycle system refers to a system in which a heat transfer medium removes heat energy from a load fluid in an evaporator to cool the load fluid and cool it to a lower temperature.

[0079] Figure 1 is a schematic structural diagram showing an example of the refrigeration cycle system of this disclosure. The refrigeration cycle system 10 is a system generally having a structure including a compressor 11, a condenser 12, an expansion valve 13, an evaporator 14, and a pump 16. Among them, the compressor 11 compresses the working medium vapor A into a high-temperature and high-pressure working medium vapor B, the condenser 12 cools and liquefies the working medium vapor B discharged from the compressor 11 into a low-temperature and high-pressure working medium C, the expansion valve 13 expands the working medium C discharged from the condenser 12 into a low-temperature and low-pressure working medium D, and the evaporator 14 heats the working medium D discharged from the expansion valve 13 into a high-temperature and low-pressure working medium vapor A.

[0080] In the refrigeration cycle system 10, the following cycles (i) to (iv) are repeated. (i) The working medium vapor A discharged from the evaporator 14 is compressed in the compressor 11 into a high-temperature and high-pressure working medium vapor B (hereinafter referred to as the "AB process"). (ii) The working medium vapor B discharged from the compressor 11 is cooled and liquefied in the condenser 12 by the fluid F into a low-temperature and high-pressure working medium C. At this time, the fluid F is heated into a fluid F' and discharged from the condenser 12 (hereinafter referred to as the "BC process"). (iii) The working medium C discharged from the condenser 12 expands in the expansion valve 13 into a low-temperature and low-pressure working medium D (hereinafter referred to as the "CD process"). (iv) The working medium D discharged from the expansion valve 13 is heated in the evaporator 14 by the load fluid E into a high-temperature and low-pressure working medium vapor A. At this time, the load fluid E is cooled into a load fluid E' and discharged from the evaporator 14 (hereinafter referred to as the "DA process").

[0081] The refrigeration cycle system 10 is a cycle system composed of adiabatic - isentropic change, isenthalpic change, and isobaric change. If the state change of the working medium is depicted on the Figure 2 shown pressure - enthalpy line (curve) diagram, the vertices can be represented by A, B, C, and D.

[0082] The AB process is a process in which the low-temperature and low-pressure working medium vapor A is adiabatically compressed in the compressor 11 into a high-temperature and high-pressure working medium vapor B, and is represented by the AB line in the Figure 2 . As described later, the working medium vapor A is introduced into the compressor 11 in a superheated state, and the obtained working medium vapor B is also a superheated state vapor. The density of the gas sucked by the compressor is Figure 2 the density (ρs) in the A state in the Figure 2 . The temperature of the gas discharged from the compressor (discharge temperature) is Figure 2 the temperature (Tx) in the B state in the Figure 2 , which is the highest temperature in the refrigeration cycle. The discharge pressure of the compressor is

[0083] the pressure (Px) in the B state in the Figure 2 , which is the highest pressure in the refrigeration cycle. Among them, since the BC process is an isobaric cooling, the discharge pressure is shown as the same value as the condensation pressure (Pc). Therefore,

[0084] in the

[0083] , for convenience, the condensation pressure is represented by Px.

[0083] The BC process is a process in which the high-temperature and high-pressure working medium vapor B is isobarically cooled in the condenser 12 into a low-temperature and high-pressure working medium C, and is represented by the BC line in the Figure 2 . The pressure at this time is the condensation pressure. Among the intersection points of the pressure - enthalpy line and the BC line, the intersection point T1 on the high-enthalpy side is the condensation temperature, and the intersection point T2 on the low-enthalpy side is the condensation boiling point temperature. Here, the temperature gradient of the condenser when the working medium is a non-azeotropic mixture is represented by the difference between T1 and T2.

[0084] The CD process is an isenthalpic expansion process that occurs in the expansion valve 13, which transforms the working medium C at low temperature and high pressure into the working medium D at low temperature and low pressure. In Figure 2 it is represented by the CD line. Among them, if T3 represents the temperature of the working medium C at low temperature and high pressure, then T2 - T3 becomes the subcooling degree (SC) of the working medium in the cycle of (i) to (iv).

[0085] The DA process is an isobaric heating process that occurs in the evaporator 14, which reverts the working medium D at low temperature and low pressure back to the working medium vapor A at high temperature and low pressure. In Figure 2 it is represented by the DA line. The pressure at this time is the evaporation pressure. Among the intersections of the pressure - enthalpy line and the DA line, the intersection T6 on the high - enthalpy side is the evaporation temperature. Here, when the working medium is a non - azeotropic mixture, the temperature gradient of the evaporator is represented by the difference between T6 and T4. If T7 represents the temperature of the working medium vapor A, then T7 - T6 becomes the superheat degree (SH) of the working medium in the cycle of (i) to (iv). Among them, T4 represents the temperature of the working medium D.

[0086] The CAP and COP of the working medium are respectively obtained by the following formulas (11), (12), (13), (14) using the enthalpies hA, hB, hC, hD of the working medium in each state of A (after evaporation, low temperature and low pressure), B (after compression, high temperature and high pressure), C (after condensation, low temperature and high pressure), D (after expansion, low temperature and low pressure) and the refrigerant mass circulation rate qmr. There is no pressure loss in the piping and heat exchanger.

[0087] When the loss work of the compressor is applied to the working medium in the form of heat, using the compressor efficiency η, the working medium vapor B' after the AB process is expressed by hA, hB, and η as follows. hB’ = hA+(hB - hA) / η

[0088] The cycle performance of the working medium is obtained by performing theoretical calculations of the refrigeration cycle of the working medium under the temperature conditions of the above - mentioned reference refrigeration cycle using the National Institute of Science and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP10.0). In addition, the physical property data of HFO-1123 and the values used in the mixing rule are obtained from Akasaka, R., Higashi, Y., Sakoda, N., Fukuda, S., and Lemmon, E.W., "Thermodynamic properties of trifluoroethene (R1123): (p, ρ, T) behavior and fundamental equation of state", International Journal of Refrigeration., 2020, 119, 457-467, and Akasaka, R., and Lemmon, E.W., "A New Fundamental Equation of State for R1123 and its Applications to Mixture Models for Mixtures with R32 and R1234yf", The 6th IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants, 2021. CAP = (hA - hD) × ρs…(11) COP = Q / P = qmr(hA - hD) / qmr(hB - hA) = (hA - hD) / (hB - hA)…(12) Q = qmr(hA - hD)…(13) P = qmr(hB - hA)…(14) Among them, considering the compressor efficiency, COP and P become the following formulas. COP = Q / P = (hA - hD) / (hB’ - hA)…(15) P = qmr(hB’ - hA)…(16)

[0089] <Temperature gradient> The temperature gradient is an index for measuring the compositional difference of the working medium of a mixture in the liquid phase and the gas phase. The temperature gradient is defined as the property that the starting temperature and the ending temperature of evaporation in a heat exchanger, such as an evaporator, or condensation in a condenser are different. In an azeotropic mixture medium, the temperature gradient is 0, and for a near-azeotropic mixture such as R410A, the temperature gradient is extremely close to 0.

[0090] If the temperature gradient is large, problems such as a decrease in the inlet temperature of the evaporator and an increased possibility of frosting will occur. Furthermore, in a heat cycle system, in order to improve the heat exchange efficiency, the working medium flowing through the heat exchanger and a heat source fluid such as water or air are usually made to flow in a countercurrent. Since the temperature difference of the heat source fluid is small in the stable operating state, it is difficult to obtain a heat cycle system with good energy efficiency in the case of a zeotropic mixture medium with a large temperature gradient. Therefore, when using a mixture as the working medium, a working medium with a moderate temperature gradient is required.

[0091] Moreover, the zeotropic mixture medium has a problem that the composition changes when filling from a pressure vessel to a refrigeration and air-conditioning device. Furthermore, in the case where the refrigerant discharged from the refrigeration and air-conditioning device leaks, the possibility of the refrigerant composition in the refrigeration and air-conditioning device changing is extremely high, and it is difficult to return the refrigerant composition to the initial state. On the other hand, an azeotropic or near-azeotropic mixture medium can avoid the above problems.

[0092] <Compression ratio> The compression ratio is expressed as the condensation pressure Pc (MPa) / evaporation pressure Pe (MPa) in the refrigeration cycle. The smaller the condensation pressure and the larger the evaporation pressure in the refrigeration cycle, the smaller the compression ratio. The smaller the compression ratio, the larger the volumetric efficiency of the compressor. Therefore, the refrigerant circulation amount increases and the device performance improves. In addition, in the present disclosure, the compression ratio is expressed as a relative compression ratio with respect to HFC-32.

[0093] <Critical temperature> The critical point is the end point on the high-pressure and high-temperature side of the saturated liquid line and the saturated vapor line. The temperature at this point is the critical temperature. Above the critical point, there is neither evaporation nor liquefaction phenomenon, and the difference between the liquid phase and the gas phase becomes unclear, and there is no phase change. When using the working medium of the present disclosure in a refrigeration cycle device, when the temperature of the air cooling the condenser is at a relatively high temperature condition, the temperature of the refrigerant after heat exchange is close to or exceeds the critical temperature on the lower temperature side than the critical temperature. Therefore, the working medium cannot be liquefied (condensed), resulting in a problem of a decrease in refrigeration performance. Therefore, the higher the critical temperature of the working medium, the better.

[0094] <Global warming potential (GWP)> In the present disclosure, unless otherwise specified, the GWP is the 100-year value of the Fifth Assessment Report (2013) of the Intergovernmental Panel on Climate Change (IPCC). The GWP of the mixture is the weighted average based on the compositional weight. To account for the GWP of the mixture, those with a GWP of less than 1 are calculated as 1.

[0095] <Concentration of HFO-1123 in the gas phase> In the present disclosure, the concentration of HFO-1123 in the gas phase (hereinafter also referred to as "HFO-1123 concentration") means the concentration (%) obtained by subtracting the concentration of HFO-1123 in the working medium filled in a closed container (set as X mass%) from the concentration of HFO-1123 in the gas phase (set as Xv mass%).

[0096] When the present inventors evaluated the HFO-1123 concentration, they obtained the following findings regarding the parameters affecting the evaluation results.

[0097] In the composition of the working medium during filling into a closed container, the lower the azeotropy, the greater the tendency for the HFO-1123 concentration to increase. The smaller the filling rate of the working medium during filling into a closed container, the greater the tendency for the HFO-1123 concentration to increase. The lower the storage temperature of the working medium in a closed container, the greater the HFO-1123 concentration.

[0098] In addition, according to the American ANSI / ASHRAE34-2016 standard, referring to the initial conditions of leakage of containers and equipment during storage, transportation, and use for determining the Worst Case of Fractionation for Flammability (WCFF), based on the above findings, the concentration of HFO-1123 is evaluated under the gas-liquid equilibrium state at -40°C after filling into a closed container at 54.4°C with a filling rate of 15%.

[0099] The gas-phase concentration of the working medium is determined by performing gas-liquid equilibrium calculations under the above conditions using the National Institute of Science and Technology (NIST) ((National Institute of Standards and Technology of the United States)) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10.0) and the National Institute of Science and Technology (NIST) Standard Reference Data Base REFLEAK Version 6.0. In addition, for the physical property data and mixing rules of HFO-1123, the values described in Akasaka, R., Higashi, Y., Sakoda, N., Fukuda, S., and Lemmon, E.W., Thermodynamic properties of trifluoroethene (R1123): (p, ρ, T) behavior and fundamental equation of state, International Journal of Refrigeration (behavior and fundamental equation of state)., 2020, 119, 457-467, Akasaka, R., and Lemmon, E.W., A New Fundamental Equation of State for R1123 and its Applications to Mixture Models for Mixtures with R32 and R1234yf (A new fundamental equation of state for R1123 and its applications in mixture models for mixtures with R32 and R1234yf), The 6th IIR Conference on Thermophysical Properties and Transfer Processes of Refrigerants (The 6th International Institute of Refrigeration Conference on the Thermophysical Properties and Transfer Processes of Refrigerants), 2021 are used.

[0100] As described above, when the concentration of HFO-1123 at the time of filling the working medium of the present disclosure is X mass%, and the concentration of HFO-1123 in the gas phase after storage is Xv mass%, the amount of HFO-1123 concentration (mass%) is represented by Xv - X. In addition, to evaluate whether the concentration of HFO-1123 in the gas phase is inhibited, a composition obtained by removing carbon dioxide from the working medium of the present disclosure is prepared. When the concentration of HFO-1123 is x mass% when the composition is filled and the concentration of HFO-1123 in the gas phase after storage is xv mass%, the amount of HFO-1123 concentrated (mass%) is represented by xv - x. The working medium of the present disclosure is compared with a composition containing no carbon dioxide, and the reduction degree of the amount of HFO-1123 concentrated (hereinafter also referred to as "concentration reduction degree") is calculated. The concentration reduction degree is based on the following formula. Concentration reduction degree (%) = [((xv - x) - (Xv - X)) / (xv - x)] × 100 It can be said that the greater the concentration reduction degree, the higher the effect of inhibiting the concentration of HFO-1123 in the gas phase. The concentration reduction degree is preferably 20% or more, more preferably 45% or more.

[0101] [Composition for thermal cycle system] The composition for a thermal cycle system of the present disclosure preferably contains the working medium for a thermal cycle of the present disclosure and a refrigeration oil.

[0102] [Refrigeration oil] As the refrigeration oil, conventionally known refrigeration oils used in a thermal cycle system can be used. Specific examples of the refrigeration oil include oxygen-containing synthetic oils (ester-based refrigeration oils, ether-based refrigeration oils, etc.), fluorine-based refrigeration oils, mineral-based refrigeration oils, and hydrocarbon synthetic oils.

[0103] As the ester-based refrigeration oil, for example, dibasic acid ester oils, polyol ester oils, complex ester oils, and polyol carbonate oils can be cited.

[0104] As the dibasic acid ester oil, preferably an ester of a dibasic acid having 5 or more and 10 or less carbon atoms (glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, etc.) and a monohydric alcohol having 1 or more and 15 or less carbon atoms with a straight-chain or branched alkyl group (methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tetradecanol, pentadecanol, etc.). The dibasic acid ester oil is preferably tricosanyl glutarate, bis(2-ethylhexyl) adipate, diisodecyl adipate, tricosanyl adipate, or bis(3-ethylhexyl) sebacate.

[0105] Examples of polyol ester oils include esters of diols (ethylene glycol, 1,3 - propanediol, propylene glycol, 1,4 - butanediol, 1,2 - butanediol, 1,5 - pentanediol, neopentyl glycol, 1,7 - heptanediol, 1,12 - dodecanediol, etc.) or polyols having 3 or more and 20 or less hydroxyl groups (trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, glycerin, sorbitol, sorbitan, sorbitol glycerol condensate, etc.) and fatty acids having 6 or more and 20 or less carbon atoms (hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, eicosanoic acid, oleic acid, etc., linear or branched fatty acids, or so - called neo - acids in which the α - carbon atom is a quaternary carbon, etc.). In addition, these polyol ester oils may also have free hydroxyl groups.

[0106] The polyol ester oil is preferably an ester of a hindered alcohol (neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, etc.), more preferably trimethylolpropane trinonanoate, pentaerythritol 2 - ethylhexanoate or pentaerythritol tetranonanoate.

[0107] The complex ester oil refers to an ester of a fatty acid and a dibasic acid with a monohydric alcohol and a polyol. The same substances as those described above can be used as the fatty acid, dibasic acid, monohydric alcohol, and polyol.

[0108] The polyol carbonate oil refers to an ester of carbonic acid and a polyol. Examples of the polyol include the same diols as those described above or the same polyols as those described above. In addition, as the polyol carbonate oil, it can also be a ring - opening polymer of a cyclic alkylene carbonate.

[0109] Examples of ether - based refrigeration oils include polyethylene ether oils and polyoxyalkylene oils.

[0110] Examples of polyethylene ether oils include polymers obtained by polymerizing vinyl ether monomers such as alkyl vinyl ethers and copolymers obtained by copolymerizing vinyl ether monomers with hydrocarbon monomers having an olefinic double bond.

[0111] The vinyl ether monomer can be one kind or two or more kinds.

[0112] Examples of hydrocarbon monomers having an olefinic double bond include ethylene, propylene, various butenes, various pentenes, various hexenes, various heptenes, various octenes, diisobutene, triisobutene, styrene, α - methylstyrene, various alkyl - substituted styrenes, etc. The hydrocarbon monomer having an olefinic double bond can be one kind or two or more kinds.

[0113] The polyethylene ether copolymer can be either a block copolymer or a random copolymer. The polyethylene ether oil can be one kind or two or more kinds.

[0114] Examples of the polyoxyalkylene oil include: polyoxyalkylene monohydric alcohols, polyoxyalkylene polyhydric alcohols; alkyl ether compounds of polyoxyalkylene monohydric alcohols or polyoxyalkylene polyhydric alcohols; and ester compounds of polyoxyalkylene monohydric alcohols or polyoxyalkylene polyhydric alcohols.

[0115] The polyoxyalkylene monohydric alcohols and polyoxyalkylene polyhydric alcohols can be produced, for example, by a method of ring-opening addition polymerization of an alkylene oxide having 2 to 4 carbon atoms (ethylene oxide, propylene oxide, etc.) in an initiator such as water or a hydroxyl group-containing compound in the presence of a catalyst such as an alkali hydroxide. In addition, the oxyalkylene units in the polyoxyalkylene chain may be the same in one molecule or may contain two or more types of oxyalkylene units. It is preferred to contain at least an oxypropylene unit in one molecule.

[0116] Examples of the initiator used in the reaction include: water; monohydric alcohols such as methanol and butanol; and polyhydric alcohols such as ethylene glycol, propylene glycol, pentaerythritol, and glycerol.

[0117] As the polyoxyalkylene oil, for example, an alkyl ether compound or an ester compound of a polyoxyalkylene monohydric alcohol or a polyoxyalkylene polyhydric alcohol is preferred. In addition, as the polyoxyalkylene oil, a polyalkylene glycol oil is preferred. Particularly preferred is an alkyl ether compound of a polyalkylene glycol in which the terminal hydroxyl group of the polyalkylene glycol called polyglycol oil is capped with an alkyl group such as a methyl group.

[0118] Examples of the fluorine-based refrigeration oil include compounds in which hydrogen atoms of a synthetic oil (mineral oil, polyalpha-olefin, alkylbenzene, alkylnaphthalene, etc. described later) are replaced with fluorine atoms, fluorine-containing oils, perfluoropolyether oils, and fluorosilicone oils.

[0119] Examples of the mineral-based refrigeration oil include mineral oils (e.g., paraffinic mineral oils and naphthenic mineral oils) refined by appropriately combining and refining the refrigeration oil fractions obtained by atmospheric distillation or vacuum distillation of crude oil (solvent desulfurization, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, clay treatment, etc.).

[0120] Examples of the hydrocarbon synthetic oil include polyalpha-olefins, alkylbenzenes, and alkylnaphthalenes.

[0121] The refrigeration oil contained in the composition for a heat cycle system may be one type or two or more types.

[0122] Among them, the refrigeration oil is preferably at least one selected from polyalkylene glycol oils, polyol ester oils, polyethylene ether oils, fluorine-containing oils, mineral oils, and hydrocarbon synthetic oils.

[0123] The above refrigeration oil may further contain at least one selected from antioxidants, extreme pressure agents, acid scavengers, oxygen scavengers, copper passivators, rust inhibitors, oiliness agents, and defoamers.

[0124] The content of the refrigeration oil in the composition for the thermal cycle system may be within a range where the effects of the present disclosure are not significantly reduced. Relative to 100 parts by mass of the working medium, it is preferably 10 to 100 parts by mass, more preferably 20 to 50 parts by mass.

[0125] (Additive) The composition for the thermal cycle system may further contain at least one known additive selected from a tracer, a stabilizer, a polymerization inhibitor, and a leak detection substance in addition to the working medium and the refrigeration oil.

[0126] The tracer is preferably added at a detectable concentration capable of detecting any dilution, contamination, or other changes in the working medium of the present disclosure.

[0127] The tracer contained in the working medium of the present disclosure may be only one kind or two or more kinds.

[0128] The tracer is not particularly limited and can be appropriately selected from commonly used tracers. It is preferable to select a compound that will not inevitably become an impurity mixed into the working medium of the present disclosure as the tracer.

[0129] Examples of the tracer include hydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons, hydrochlorocarbons, fluorocarbons, deuterated hydrocarbons, deuterated hydrofluorocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodinated compounds, alcohols, aldehydes, ketones, nitrous oxide (N 2 O), etc. Among them, the tracer is preferably selected from at least one of hydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons, hydrochlorocarbons, fluorocarbons, and fluoroethers.

[0130] Examples of the preferred tracer include the following compounds. HC-40 (chloromethane, CH 3 Cl) HFC-161 (fluoroethane, CH 3 CH 2 F) HFC-245fa (1,1,1,3,3-pentafluoropropane, CF 3 CH 2 CHF 2 ) HFC-236fa (1,1,1,3,3,3-hexafluoropropane, CF 3 CH 2 CF 3 ) HFC-236ea (1,1,1,2,3,3-hexafluoropropane, CF 3 CHFCHF 2 ) HCFC-22 (chlorodifluoromethane, CHClF2 ) HCFC-31 (chlorofluoromethane, CH 2 ClF) CFC-1113 (chlorotrifluoroethylene, CF 2 =CClF) HFe-125 (trifluoromethyl-difluoromethyl ether, CF 3 OCHF 2 ) HFe-134a (trifluoromethyl-fluoromethyl ether, CF 3 OCH 2 F) HFe-143a (trifluoromethyl-methyl ether, CF 3 OCH 3 ) HFe-227ea (trifluoromethyl-tetrafluoroethyl ether, CF 3 OCHFCF 3 ) HFE-236fa (trifluoromethyl-trifluoroethyl ether, CF 3 OCH 2 CF 3 )

[0131] The content of the tracer is preferably 10 ppm to 1000 ppm, more preferably 30 ppm to 500 ppm, further preferably 50 ppm to 300 ppm, particularly preferably 75 ppm to 250 ppm, and most preferably 100 ppm to 200 ppm, relative to the total amount of the working medium.

[0132] The stabilizer is a component that improves the stability of the working medium for thermal cycling against heat and oxidation. As the stabilizer, conventionally known stabilizers can be exemplified, such as oxidation resistance improvers, heat resistance improvers, and metal deactivators.

[0133] As the oxidation resistance improver and heat resistance improver, for example, N,N'-diphenylbenzidine, p-octyldiphenylamine, p,p'-dioctyldiphenylamine, N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine, N-(p-dodecyl)phenyl-2-naphthylamine, di-1-naphthylamine, di-2-naphthylamine, N-alkylphenylthiazine, 6-(tert-butyl)phenol, 2,6-di-(tert-butyl)phenol, 4-methyl-2,6-di-(tert-butyl)phenol, 4,4'-methylenebis(2,6-di-tert-butylphenol) can be exemplified. The oxidation resistance improver and heat resistance improver can be one kind or two or more kinds.

[0134] Examples of the metal deactivator include imidazole, benzimidazole, 2-mercaptobenzothiazole, 2,5-dimethylthiadiazole, salicylpropylenediamine, pyrazole, benzotriazole, tolyltriazole, 2-methylbenzimidazole, 3,5-dimethylpyrazole, methylenebis-benzotriazole, organic acids or their esters, primary, secondary or tertiary aliphatic amines, amine salts of organic or inorganic acids, heterocyclic nitrogen-containing compounds, amine salts of alkyl phosphates or their derivatives.

[0135] The content of the stabilizer only needs to be within the range that does not significantly reduce the effect of the present disclosure. Relative to 100 parts by mass of the working medium, it is usually 0.01% by mass to 5% by mass, preferably 0.05% by mass to 3% by mass, more preferably 0.1% by mass to 2% by mass, further preferably 0.25% by mass to 1.5% by mass, and particularly preferably 0.5% by mass to 1% by mass.

[0136] The polymerization inhibitor is not particularly limited and can be appropriately selected from commonly used polymerization inhibitors. The polymerization inhibitor contained in the working medium of the present disclosure can be only one kind or two or more kinds.

[0137] Examples of the polymerization inhibitor include 4-methoxy-1-naphthol, hydroquinone, methyl ether of hydroquinone, dimethyl-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, and benzotriazole.

[0138] The content of the polymerization inhibitor is not particularly limited. Relative to the total amount of the working medium, it is usually 0.01% by mass to 5% by mass, preferably 0.05% by mass to 3% by mass, more preferably 0.1% by mass to 2% by mass, further preferably 0.25% by mass to 1.5% by mass, and particularly preferably 0.5% by mass to 1% by mass.

[0139] Examples of the leak detection substance include ultraviolet fluorescent dyes, odors, and odor masking agents.

[0140] Examples of the ultraviolet fluorescent dye include ultraviolet fluorescent dyes known in the past, such as those described in U.S. Patent No. 4,249,412, Japanese Patent Application Laid-Open No. Hei 10-502737, Japanese Patent Application Laid-Open No. 2007-511645, Japanese Patent Application Laid-Open No. 2008-500437, and Japanese Patent Application Laid-Open No. 2008-531836.

[0141] Examples of the odor masking agent include known perfumes, such as those described in Japanese Patent Application Laid-Open No. 2008-500437 and Japanese Patent Application Laid-Open No. 2008-531836.

[0142] When using the leak detection substance, a solubilizer that improves the solubility of the leak detection substance in the working medium for thermal cycling can also be used.

[0143] Examples of solubilizers include those described in Japanese Patent Application Laid-Open No. 2007-511645, Japanese Patent Application Laid-Open No. 2008-500437, and Japanese Patent Application Laid-Open No. 2008-531836.

[0144] The content of the leak detection substance only needs to be within a range that does not significantly reduce the effects of the present disclosure. Preferably, it is 2 parts by mass or less, and more preferably 0.5 parts by mass or less, relative to 100 parts by mass of the working medium.

[0145] The composition for a heat cycle system is used in a heat cycle system. The heat cycle system can be a heat pump system that utilizes the warmth obtained from a condenser, or a refrigeration cycle system that utilizes the cold obtained from an evaporator.

[0146] Specific examples of the heat cycle system include refrigeration and freezing equipment, air conditioning equipment, power generation systems, heat transfer devices, and secondary coolers. Among them, the heat cycle system can stably and safely exhibit heat cycle performance even in a higher-temperature working environment, so it is preferably used as air conditioning equipment that is usually installed outdoors. In addition, the heat cycle system is also preferably used as refrigeration and freezing equipment.

[0147] Specific examples of the air conditioning equipment include household air conditioners (such as indoor air conditioners and house air conditioners), commercial air conditioners (such as shop combined air conditioners, building combined air conditioners, and equipment combined air conditioners), gas engine heat pumps, train air conditioning devices, and automotive air conditioning devices. The automotive air conditioning device is preferably an air conditioning device for gasoline vehicles, hybrid vehicles, electric vehicles, or hydrogen vehicles, and more preferably an air conditioning device for electric vehicles.

[0148] Specific examples of the refrigeration and freezing equipment include display cabinets (such as refrigerated display cabinets and frozen display cabinets), refrigerators, freezers, chillers, refrigeration and freezing units, refrigerators for refrigerated and frozen warehouses, turbo refrigerators, screw refrigerators, vending machines, and ice makers.

[0149] As the power generation system, a power generation system based on a Rankine cycle system is preferred. As the power generation system, specifically, a system can be exemplified in which a working medium that heats a working medium using geothermal energy, solar energy, medium to high-temperature waste heat of about 50°C or more and 200°C or less in an evaporator to make it into a high-temperature and high-pressure state steam adiabatically expands in an expander, and the work generated by this adiabatic expansion is used to drive a generator to generate electricity.

[0150] As a heat transfer device, a latent heat transfer device is preferred. As the latent heat transfer device, heat pipes and two-phase closed thermosyphon devices that utilize phenomena such as evaporation, boiling, and condensation of the working medium enclosed in the device for latent heat transfer can be cited. Heat pipes are suitable for relatively small cooling devices such as cooling devices for the heat-generating parts of semiconductor elements or electronic devices. Since the two-phase closed thermosyphon device does not require a wick, it has a simple structure and is therefore widely used in gas-fired heat exchangers, promoting road snow melting and anti-freezing, etc.

[0151] [Storage Method of Working Medium for Heat Cycle] The storage method of the working medium of the present invention includes the step of storing a working medium for heat cycle containing HFO-1123, the above-mentioned low-boiling compound, and the above-mentioned high-boiling compound. The low-boiling compound is at least one selected from carbon dioxide, R116, and R41, and the high-boiling compound is at least two selected from HFC-32, HFO-1234yf, HFO-1234ze(E), HFO-1243zf, PFC-14, HFC-134, HFC-143a, HFC-227ea, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

[0152] The preferred forms of HFO-1123, the low-boiling compound, and the high-boiling compound used in the storage method of the working medium of the present invention are as described above.

[0153] [Manufacturing Method of Working Medium for Heat Cycle] The manufacturing method of the working medium of the present disclosure includes the step of mixing HFO-1123, the above-mentioned low-boiling compound, and the above-mentioned high-boiling compound. The low-boiling compound is at least one selected from carbon dioxide, R116, and R41, and the high-boiling compound is at least two selected from HFC-32, HFO-1234yf, HFO-1234ze(E), HFO-1243zf, PFC-14, HFC-134, HFC-143a, HFC-227ea, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

[0154] The preferred forms of HFO-1123, the low-boiling compound, and the high-boiling compound used in the manufacturing method of the working medium of the present invention are as described above.

[0155] The method of mixing HFO-1123, the above-mentioned low-boiling compound, and the above-mentioned high-boiling compound is not particularly limited. It can be a method of adding each component to the container simultaneously, or a method of adding each component to the container separately.

[0156] [Storage Container for Working Medium for Heat Cycle] The storage container for the working medium of the present disclosure is a sealed storage container in which the working medium for thermal cycling containing HFO-1123, the above-mentioned low-boiling compound, and the above-mentioned high-boiling compound is stored in a state where the gas phase and the liquid phase coexist. The low-boiling compound is at least one selected from carbon dioxide, R116, and R41, and the high-boiling compound is at least two selected from HFC-32, HFO-1234yf, HFO-1234ze(E), HFO-1234zf, PFC-14, HFC-134, HFC-143a, HFC-227ea, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

[0157] The storage container only needs to be a container that can store the working medium in a state where the gas phase and the liquid phase coexist under the internal pressure, and there is no particular limitation.

[0158] The material of the surface of the storage container in contact with the working medium is preferably a resin material, a metal material, or a glass material. The storage container can be, for example, a container entirely made of resin or metal, or a container having a multilayer structure with the innermost layer made of resin or metal, or a container having a film made of resin or metal on the surface in contact with the working medium. In addition, the storage container can be a glass container or a glass-lined container.

[0159] As the resin used for the container, for example, it is preferably a resin containing at least one selected from polyvinyl chloride resin (PVC), polyethylene resin (PE), polypropylene resin (PP), polystyrene resin (PS), acrylonitrile-butadiene-styrene resin (ABS), acrylonitrile-styrene resin (AS), polymethyl methacrylate resin (PMMA), polyvinyl alcohol resin (PVA), polyvinylidene chloride resin (PVDC), polyethylene terephthalate resin (PET), polyamide (nylon) resin (PA), polyacetal resin (POM), polycarbonate resin (PC), polyphenylene ether resin (PPE), polybutylene terephthalate resin (PBT), polyvinylidene fluoride resin (PVDF), perfluoroalkoxy alkane resin (PFA), polytetrafluoroethylene resin (PTFE), polysulfone resin (PSU), polyethersulfone resin (PES), polyphenylene sulfide resin (PPS), polyarylate resin (PAR), polyamideimide resin (PAI), polyetherimide resin (PEI), polyetheretherketone resin (PEEK), polyimide resin (PI), phenolic resin (PF), urea resin (UF), melamine resin (MF), unsaturated polyester resin (UP), epoxy resin (EP), silicone resin (SI), polyurethane resin (PUR), epoxy-phenolic resin, and phenol butyral resin.

[0160] As the metal used for the container, preferably: a metal selected from the group consisting of iron, copper, aluminum, stainless steel, titanium, nickel, zinc, tin, brass, magnesium, chromium, lead, silver, tungsten, and tantalum; an alloy containing at least one selected from the above metal group; or a compound containing at least one selected from the above metal group.

[0161] As the alloy, for example, nickel-chromium plating, solder, tin plating, etc. can be cited. As the metal-containing compound, for example, aluminum sulfate, zinc phosphate, iron phosphate, etc. can be cited.

[0162] As the glass used for the container, soda-lime glass, borosilicate glass, quartz glass, etc. can be cited.

[0163] The storage container can be made of a material different from the surface in contact with the container body and the working medium. As the material for the container body, iron (steel), stainless steel, carbon steel, manganese steel, chrome-molybdenum steel, other low-alloy steels, aluminum alloy, glass can be cited. As the stainless steel, SUS316, SUS304, and JFE443CT can be cited.

[0164] The shape and size of the storage container can be designed to match the purpose. As the fixed storage container, storage tanks, transportable containers, containers for transportation, etc. can be cited. As the transportable container, 1L glass bottles, 20L pails (pail cans), 200L drums, ton containers, aerosol cans, high-pressure gas containers (non-refillable containers, welded containers, seamless containers, etc.) can be cited. As the container for transportation, oil tank trucks, ISO containers, self-loading machines, etc. can be cited. Examples

[0165] Hereinafter, the present disclosure will be described more specifically by way of examples. However, the present disclosure is not limited to the following examples as long as it does not exceed the gist.

[0166] [Examples 1-1 to 1-100, Examples 1A to 1Z, Example 1a] In Examples 1-1 to 1-100, a working medium containing HFO-1123, carbon dioxide, HFC-32, and HFO-1234yf was prepared to achieve the compositions (mass %) shown in Tables 1 to 9. In Examples 1A to 1Z, Example 1a, a working medium containing HFO-1123, HFC-32, and HFO-1234yf was prepared to achieve the compositions (mass %) shown in Tables 1 to 9. Each working medium was filled into a closed container at 54.4 °C with a filling rate of 15%, and evaluated under the gas-liquid equilibrium state at -40 °C.

[0167] In Examples 1-1 to 1-100, the concentration of HFO-1123 at the time of filling is set to X mass%, and the concentration of HFO-1123 in the gas phase after storage is set to Xv mass%. The amount of HFO-1123 concentrated (mass%) is represented by Xv - X. Here, both Xv and X are based on the total content (100 mass%) of HFO-1123, carbon dioxide, HFC-32, and HFO-1234yf. In Examples 1A to 1Z and Example 1a, the concentration of HFO-1123 at the time of filling is set to x mass%, and the concentration of HFO-1123 in the gas phase after storage is set to xv mass%. The amount of HFO-1123 concentrated (mass%) is represented by xv - x. Here, both xv and x are based on the total content (100 mass%) of HFO-1123, HFC-32, and HFO-1234yf. Among the working media containing carbon dioxide (four-component system) and the working media not containing carbon dioxide (three-component system), the working media with the same composition other than carbon dioxide are compared with each other, and the reduction degree of the amount of HFO-1123 concentrated (hereinafter also referred to as "concentration reduction degree") is calculated. For example, Comparative Examples 1-1 to 1-3 are compared with Example 1A. The concentration reduction degree is calculated according to the following formula. Concentration reduction degree (%) = [{(xv - x) - (Xv - X)} / (xv - x)] × 100

[0168] [Examples 2-1 to 2-100, Examples 2A to 2Z, Example 2a] In Examples 2-1 to 2-100, a working medium containing HFO-1123, carbon dioxide, HFC-32, and HFO-1234ze(E) is prepared to achieve the compositions (mass%) shown in Tables 10 to 18. In Examples 2A to 2Z and Example 2a, a working medium containing HFO-1123, HFC-32, and HFO-1234ze(E) is prepared to achieve the compositions (mass%) shown in Tables 10 to 18. Each working medium is filled into a closed container at 54.4°C and a filling rate of 15%, and evaluated under the gas-liquid equilibrium state at -40°C.

[0169] In Examples 2-1 to 2-100, the concentration of HFO-1123 at the time of filling is set to X mass%, and the concentration of HFO-1123 in the gas phase after storage is set to Xv mass%. The amount of HFO-1123 concentrated (mass%) is represented by Xv - X. Here, both Xv and X are based on the total content (100 mass%) of FO-1123, carbon dioxide, HFC-32, and HFO-1234ze(E). In Examples 2A to 2Z and 2a, the concentration of HFO-1123 during filling was set to x mass%, and the concentration of HFO-1123 in the gas phase after storage was set to xv mass%. The amount of HFO-1123 concentrated (mass%) is represented by xv - x. Here, both xv and x are based on the total content (100 mass%) of HFO-1123, HFC-32, and HFO-1234ze(E). In the working media containing carbon dioxide (four-component system) and the working media without carbon dioxide (three-component system), the working media with the same composition other than carbon dioxide were compared with each other, and the degree of concentration reduction was calculated. For example, Comparative Examples 2-1 to 2-3 were compared with Example 2A. The calculation method of the degree of concentration reduction is as described above.

[0170] When the degree of concentration reduction is less than 25%, it is evaluated as C; when it is 25% or more and less than 45%, it is evaluated as B; when it is 45% or more, it is evaluated as A. The GWP was also calculated. Tables 1 to 18 show the evaluation results.

[0171] Table 1 Example 1A Example 1-1 Example 1-2 Example 1-3 Example 1B Example 1-4 Example 1-5 Example 1-6 Example 1-7 Example 1C Example 1-8 Example 1-9 Example 1-10 Example 1-11 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 70.0 68.6 68.25 67.9 67.2 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 - 2.0 2.50 3.0 4.0 HFC-32 6.0 5.9 5.9 5.8 6.0 5.9 5.85 5.8 5.8 6.0 5.9 5.85 5.8 5.8 HFO-1234yf 63.0 61.7 61.4 61.1 54.0 52.9 52.65 52.4 51.8 24.0 23.5 23.40 23.3 23.0 GWP 41 40 40 40 41 40 40 40 40 41 40 40 40 39 Degree of concentration reduction 19.76 24.72 28.81 20.31 25.13 29.78 38.99 28.48 35.41 42.27 55.65 Evaluation C C B C B B B B B B A

[0172] Table 2 Example 1D Example 1-12 Example 1-13 Example 1-14 Example 1E Example 1-15 Example 1-16 Example 1-17 Example 1-18 Example 1F Example 1-19 Example 1-20 Example 1-21 Example 1-22 HFO-1123 31.0 30.4 30.2 30.07 40.0 39.2 39.0 38.8 38.4 60.0 58.8 58.5 58.2 57.6 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 HFC-32 11.0 10.8 10.7 10.67 11.0 10.8 10.7 10.7 10.6 11.0 10.8 10.7 10.7 10.6 HFO-1234yf 58.0 56.8 56.6 56.26 49.0 48.0 47.8 47.5 47.0 29.0 28.4 28.3 28.1 27.8 GWP 75 74 73 73 75 73 73 73 72 75 73 73 73 72 Degree of concentration reduction 19.39 24.19 28.58 20.31 25.08 29.99 39.22 25.18 31.20 37.41 49.26 Evaluation C C B C B B B B B B A

[0173] Table 3 Example 1G Example 1-23 Example 1-24 Example 1-25 Example 1-26 Example 1H Example 1-27 Example 1-28 Example 1-29 Example 1I Example 1-30 Example 1-31 Example 1-32 Example 1-33 HFO-1123 70.0 68.6 68.3 67.9 67.2 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 <![CDATA[CO 2 > - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 HFC-32 11.0 10.8 10.7 10.7 10.6 16.0 15.7 15.6 15.5 16.0 15.7 15.6 15.5 15.4 HFO-1234yf 19.0 18.6 18.5 18.4 18.2 53.0 51.9 51.7 51.4 44.0 43.1 42.9 42.7 42.2 GWP 75 73 73 72 72 109 107 106 106 109 107 106 106 104 Degree of concentration reduction 32.05 39.55 47.86 63.13 19.17 24.02 28.24 20.39 25.30 30.15 39.63 Evaluation B B A A C C B C B B B

[0174] Table 4 Example 1J Example 1-34 Example 1-35 Example 1-36 Example 1-37 Example 1K Example 1-38 Example 1-39 Example 1-40 Example 1-41 Example 1L Example 1-42 Example 1-43 Example 1-44 HFO-1123 60.0 58.8 58.5 58.2 57.6 70.0 68.6 68.25 67.9 67.2 31.0 30.4 30.2 30.07 <![CDATA[CO 2 > - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 HFC-32 16.0 15.7 15.6 15.5 15.4 16.0 15.7 15.60 15.5 15.4 21.5 21.1 21.0 20.86 HFO-1234vf 24.0 23.5 23.4 23.3 23.0 14.0 13.7 13.65 13.6 13.4 47.5 46.6 46.3 46.08 GWP 109 106 106 105 104 108 106 106 105 104 146 143 142 142 Degree of concentration reduction 26.87 33.41 39.80 52.66 36.70 45.68 54.55 72.16 19.24 24.10 28.51 Evaluation B B B A B A A A C C B

[0175] Table 5 Example 1M Example 1-45 Example 1-46 Example 1-47 Example 1-48 Example 1N Example 1-49 Example 1-50 Example 1-51 Example 1-52 Example 1O Example 1-53 Example 1-54 Example 1-55 Example 1-56 HFO-1123 40.0 39.2 39.0 38.8 38.4 60.0 58.8 58.5 58.2 57.6 70.0 68.6 68.25 67.9 67.2 <![CDATA[CO 2 > - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 HFC-32 21.5 21.1 21.0 20.9 20.6 21.5 21.1 21.0 20.9 20.6 21.5 21.1 20.96 20.9 20.6 HFO-1234yf 38.5 37.7 37.5 37.3 37.0 18.5 18.1 18.0 17.9 17.8 8.5 8.3 8.29 8.2 8.2 GWP 146 143 142 142 140 146 143 142 141 140 146 143 142 141 140 Degree of concentration reduction 20.71 25.75 30.72 40.15 30.67 35.93 43.01 56.35 43.27 53.65 64.33 84.21 Evaluation C B B B B B B A B A A A

[0176] Table 6 Example 1P Example 1-57 Example 1-58 Example 1-59 Example 1Q Example 1-60 Example 1-61 Example 1-62 Example 1-63 Example 1R Example 1-64 Example 1-65 Example 1-66 Example 1-67 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 60.0 58.8 58.5 58.2 57.6 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 HFC-32 29.0 28.4 28.3 28.1 29.0 28.4 28.3 28.1 27.8 29.0 28.4 28.3 28.1 27.8 HFO-1234vf 40.0 39.2 39.0 38.8 31.0 30.4 30.2 30.1 29.8 11.0 10.8 10.7 10.7 10.6 GWP 197 193 192 191 197 193 192 191 189 196 193 192 191 189 Degree of concentration reduction 19.18 24.23 39.33 20.99 26.17 31.21 40.92 31.63 39.46 46.96 61.74 Evaluation C C B C B B B B B A A

[0177] Table 7 Example 1S Example 1-68 Example 1-69 Example 1-70 Example 1T Example 1-71 Example 1-72 Example 1-73 Example 1-74 Example 1U Example 1-75 Example 1-76 Example 1-77 Example 1-78 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 50.0 49.0 48.75 48.5 48.0 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 2.0 2.50 3.0 4.0 HFC-32 36.0 35.3 35.1 34.9 36.0 35.3 35.1 34.9 34.6 36.0 35.3 35.10 34.9 34.6 HFO-1234yf 33.0 32.3 32.2 32.0 24.0 23.5 23.4 23.3 23.0 14.0 13.7 13.65 13.6 13.4 GWP 244 239 238 237 244 239 238 237 234 244 239 238 237 234 Degree of concentration reduction 19.26 24.30 28.46 21.39 26.61 31.67 41.57 25.35 31.45 37.46 49.29 Evaluation C C B C B B B B B B A

[0178] Table 8 Example 1V Example 1-79 Example 1-80 Example 1-81 Example 1W Example 1-82 Example 1-83 Example 1-84 Example 1-85 Example 1× Example 1-86 Example 1-87 Example 1-88 Example 1-89 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 50.0 49.0 48.75 48.50 48.0 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 - 2.0 2.50 3.00 4.0 HFC-32 40.0 39.2 39.0 38.8 40.0 39.2 39.0 38.8 38.4 40.0 39.2 39.00 38.80 38.4 HFO-1234yf 29.0 28.4 28.3 28.1 20.0 19.6 19.5 19.4 19.2 10.0 9.8 9.75 9.70 9.6 GWP 271 266 264 263 271 266 264 263 260 271 266 264 263 260 Degree of concentration reduction 19.39 24.44 28.59 21.53 25.02 31.84 41.75 25.64 31.87 37.91 49.82 Evaluation C C B C B B B B B B A

[0179] Table 9 Example 1Y Example 1-90 Example 1-91 Example 1-92 Example 1Z Example 1-93 Example 1-94 Example 1-95 Example 1-96 Example 1a Example 1-97 Example 1-98 Example 1-99 Example 1-100 HFO-1123 31.0 30.4 30.2 30.07 45.0 44.1 43.9 43.65 43.2 50.0 49.0 48.75 48.50 48.00 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.00 4.0 - 2.0 2.50 3.00 4.00 HFC-32 44.0 43.1 42.9 42.68 44.0 43.1 42.9 42.68 42.2 44.0 43.1 42.90 42.68 42.24 HFO-1234vf 25.0 24.5 24.4 24.25 11.0 10.8 10.7 10.67 10.6 6.0 5.9 5.85 5.82 5.76 GWP 298 292 291 289 298 292 291 289 286 298 292 291 289 286 Degree of concentration reduction 19.41 24.45 28.89 23.40 28.93 34.63 45.35 25.87 32.17 38.29 50.14 Evaluation C C B C B B A B B B A

[0180] Table 10 Example 2A Example 2-1 Example 2-2 Example 2-3 Example 2B Example 2-4 Example 2-5 Example 2-6 Example 2-7 Example 2C Example 2-8 Example 2-9 Example 2-10 Example 2-11 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.00 38.8 38.4 70.0 68.6 68.25 67.9 67.2 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.50 3.0 4.0 - 2.0 2.50 3.0 4.0 HFC-32 6.0 5.9 5.9 5.8 6.0 5.9 5.85 5.8 5.8 6.0 5.9 5.85 5.8 5.8 HFO-1234ze(E) 63.0 61.7 61.4 61.1 54.0 52.9 52.65 52.4 51.8 24.0 23.5 23.40 23.3 23.0 GWP 41.3 40.4 40.2 40.0 41.2 40.4 40.2 40.0 39.6 40.9 40.1 39.9 39.7 39.3 Degree of concentration reduction 18.31 22.67 26.37 18.35 22.53 26.62 34.54 24.88 30.73 36.46 48.09 Evaluation C C B C C B B C B B A

[0181] Table 11 Example 2D Example 2-12 Example 2-13 Example 2-14 Example 2E Example 2-15 Example 2-16 Example 2-17 Example 2-18 Example 2F Example 2-19 Example 2-20 Example 2-21 Example 2-22 HFO-1123 31.0 30.4 30.2 30.07 40.0 39.2 39.0 38.8 38.4 60.0 58.8 58.5 58.2 57.6 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 HFC-32 11.0 10.8 10.7 10.67 11.0 10.8 10.7 10.7 10.6 11.0 10.8 10.7 10.7 10.6 HFO-1234ze(E) 58.0 56.8 56.6 56.26 49.0 48.0 47.8 47.5 47.0 29.0 28.4 28.3 28.1 27.8 GWP 75.1 73.6 73.2 72.8 75.0 73.5 73.1 72.7 72.0 74.8 73.3 72.9 72.6 71.8 Degree of concentration reduction 17.71 21.86 25.79 18.15 22.28 26.51 34.39 21.90 27.01 32.33 42.23 Evaluation C C B C C B B C B B B

[0182] Table 12 Example 2G Example 2-23 Example 2-24 Example 2-25 Example 2-26 Example 2H Example 2-27 Example 2-28 Example 2-29 Example 2I Example 2-30 Example 2-31 Example 2-32 Example 2-33 HFO-1123 70.0 68.6 68.3 67.9 67.2 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 <![CDATA[CO 2 > - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 HFC-32 11.0 10.8 10.7 10.7 10.6 16.0 15.7 15.6 15.5 16.0 15.7 15.6 15.5 15.4 HFO-1234ze(E) 19.0 18.6 18.5 18.4 18.2 53.0 51.9 51.7 51.4 44.0 43.1 42.9 42.7 42.2 GWP 74.7 73.2 72.8 72.5 71.7 108.9 106.7 106.2 105.6 108.8 106.6 106.1 105.5 104.5 Degree of concentration reduction 27.87 34.20 41.21 54.02 17.42 21.63 25.31 18.16 22.38 26.52 34.59 Evaluation B B B A C C B C C B B

[0183] Table 13 Example 2J Example 2-34 Example 2-35 Example 2-36 Example 2-37 Example 2K Example 2-38 Example 2-39 Example 2-40 Example 2-41 Example 2L Example 2-42 Example 2-43 Example 2-44 HFO-1123 60.0 58.8 58.5 58.2 57.6 70.0 68.6 68.25 67.9 67.2 31.0 30.38 30.2 30.07 <![CDATA[CO 2 > - 2.0 2.5 3.0 4.0 - 2.0 2.50 3.0 4.0 - 2.0 2.5 3.0 HFC-32 16.0 15.7 15.6 15.5 15.4 16.0 15.7 15.60 15.5 15.4 21.5 21.07 21.0 20.86 HFO-1234ze(E) 24.0 23.5 23.4 23.3 23.0 14.0 13.7 13.65 13.6 13.4 47.5 46.55 46.3 46.08 GWP 108.6 106.4 105.9 105.3 104.3 108.5 106.3 105.8 105.2 104.2 146.0 143.1 142.4 141.7 Degree of concentration reduction 23.36 28.87 34.31 45.15 31.98 39.60 47.11 62.33 17.44 21.68 25.48 Evaluation C B B A B B A A C C B

[0184] Table 14 Example 2M Example 2-45 Example 2-46 Example 2-47 Example 2-48 Example 2N Example 2-49 Example 2-50 Example 2-51 Example 2-52 Example 2O Example 2-53 Example 2-54 Example 2-55 Example 2-56 HFO-1123 40.0 39.2 39.0 38.8 38.4 60.0 58.8 58.5 58.2 57.6 70.0 68.6 68.25 67.9 67.2 <![CDATA[CO 2 > - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 - 2.0 2.50 3.0 4.0 HFC-32 21.5 21.1 21.0 20.9 20.6 21.5 21.1 21.0 20.9 20.6 21.5 21.1 20.96 20.9 20.6 HFO-1234ze(E) 38.5 37.7 37.5 37.3 37.0 18.5 18.1 18.0 17.9 17.8 8.5 8.3 8.29 8.2 8.2 GWP 145.9 143.0 142.3 141.6 140.1 145.7 142.8 142.1 141.4 140.0 145.6 142.8 142.0 141.3 139.9 Degree of concentration reduction 18.40 22.78 27.01 34.98 25.32 31.44 37.41 48.83 38.53 979.51 975.00 965.98 Evaluation C C B B B B B A B A A A

[0185] Table 15 Example 2P Example 2-57 Example 2-58 Example 2-59 Example 2Q Example 2-60 Example 2-61 Example 2-62 Example 2-63 Example 2R Example 2-64 Example 2-65 Example 2-66 Example 2-67 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 60.0 58.8 58.5 58.2 57.6 <![CDATA[CO 2 > - 2.0 2.5 3.0 - 2.0 2.5 3.0 4.0 - 2.0 2.5 3.0 4.0 HFC-32 29.0 28.4 28.3 28.1 29.0 28.4 28.3 28.1 27.8 29.0 28.4 28.3 28.1 27.8 HFO-1234ze(E) 40.0 39.2 39.0 38.8 31.0 30.4 30.2 30.1 29.8 11.0 10.8 10.7 10.7 10.6 GWP 196.7 192.8 191.8 190.9 196.6 192.7 191.8 190.8 188.8 196.4 192.5 191.6 190.6 188.6 Degree of concentration reduction 17.45 21.83 25.49 18.82 23.33 27.62 36.02 28.54 35.54 42.15 55.36 Evaluation C C B C C B B B B B A

[0186] Table 16 Example 2S Example 2-68 Example 2-69 Example 2-70 Example 2T Example 2-71 Example 2-72 Example 2-73 Example 2-74 Example 2U Example 2-75 Example 2-76 Example 2-77 Example 2-78 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 50.0 49.0 48.75 48.5 48.0 <![CDATA[CO 2 > 2.0 2.5 3.0 2.0 2.5 3.0 4.0 2.0 2.50 3.0 4.0 HFC-32 36.0 35.3 35.1 34.9 36.0 35.3 35.1 34.9 34.6 36.0 35.3 35.10 34.9 34.6 HFO-1234ze(E) 33.0 32.3 32.2 32.0 24.0 23.5 23.4 23.3 23.0 14.0 13.7 13.65 13.6 13.4 GWP 244.1 239.2 238.0 236.8 244.0 239.1 237.9 236.7 234.2 243.9 239.0 237.8 236.6 234.1 Degree of concentration reduction 17.68 22.07 25.83 19.49 24.03 28.52 37.30 23.16 28.66 34.08 44.69 Evaluation C C B C C B B C B B B

[0187] Table 17 Example 2V Example 2-79 Example 2-80 Example 2-81 Example 2W Example 2-82 Example 2-83 Example 2-84 Example 2-85 Example 2X Example 2-86 Example 2-87 Example 2-88 Example 2-89 HFO-1123 31.0 30.4 30.2 30.1 40.0 39.2 39.0 38.8 38.4 50.0 49.0 48.75 48.50 48.0 <![CDATA[CO 2 > 2.0 2.5 3.0 2.0 2.5 3.0 4.0 2.0 2.50 3.00 4.0 HFC-32 40.0 39.2 39.0 38.8 40.0 39.2 39.0 38.8 38.4 40.0 39.2 39.00 38.80 38.4 HFO-1234ze(E) 29.0 28.4 28.3 28.1 20.0 19.6 19.5 19.4 19.2 10.0 9.8 9.75 9.70 9.6 GWP 271.1 265.7 264.3 263.0 271.0 265.6 264.3 262.9 260.2 270.9 265.5 264.2 262.8 260.1 Degree of concentration reduction 17.88 22.37 26.13 19.75 24.49 29.03 37.92 23.94 29.68 35.33 46.13 Evaluation C C B C C B B C B B

[0188] Table 18 Example 2× Example 2-90 Example 2-91 Example 2-92 Example 2Z Example 2-93 Example 2-94 Example 2-95 Example 2-96 Example 2a Example 2-97 Example 2-98 Example 2-99 Example 2-100 HFO-1123 31.0 30.4 30.2 30.07 40.0 39.2 39.0 38.80 38.4 50.0 49.0 48.75 48.50 48.00 <![CDATA[CO 2 > 2.0 2.5 3.0 2.0 2.5 3.00 4.0 2.0 2.50 3.00 4.00 HFC-32 44.0 43.1 42.9 42.68 44.0 43.1 42.9 42.68 42.2 44.0 43.1 42.90 42.68 42.24 HFO-1234ze(E) 25.0 24.5 24.4 24.25 16.0 15.7 15.6 15.52 15.4 6.0 5.9 5.85 5.82 5.76 GWP 298.1 292.2 290.7 289.2 298.0 292.1 290.6 289.1 286.2 297.9 292.0 290.5 289.0 286.1 Degree of concentration reduction 17.99 22.55 26.54 20.12 24.97 29.60 38.59 24.73 30.67 36.52 47.78 Evaluation C C B C C B B C B B A

[0189] As shown in Tables 1 to 18, in Examples 1-1 to 1-100 and Examples 2-1 to 2-100, the concentration of HFO-1123 in the gas phase can be suppressed.

[0190] [Examples 3-1 to 3-78] In Examples 3-1 to 3-78, for a working medium containing HFO-1123, carbon dioxide, HFC-32, and HFO-1234yf with the compositions (mass %) shown in Tables 19 to 21, the temperature gradient of the evaporator (denoted as "TG" in the table, unit: °C), the condensation pressure (denoted as "Pc" in the table), the compression ratio (denoted as "Pc / Pe" in the table), CAP, and COP are obtained by performing theoretical calculations of the refrigeration cycle under the above conditions. In Tables 19 to 21, when the formula (1) is satisfied, it is denoted as A, and when it is not satisfied, it is denoted as B. In addition, the degree of concentration reduction is calculated in the same manner as in Example 1-1. When the degree of concentration reduction is less than 25%, it is evaluated as C, when it is 25% or more and less than 45%, it is evaluated as B, and when it is 45% or more, it is evaluated as A. The GWP is also calculated. Tables 19 to 21 show the measurement results and evaluation results.

[0191] Table 19 HFO-1123 <![CDATA[CO 2 > HFC-32 HFO-1234vf GWP TG Pc Pc / Pe CAP COP Equation (1) Degree of concentration reduction Evaluation Example 3-1 60 2.7 3 34.3 21 7.7 0.949 0.990 0.920 0.977 B 31.45 B Example 3-2 60 2.7 5 32.3 34 7.4 0.973 0.987 0.942 0.974 B 32.40 B Example 3-3 80 2.7 5 12.3 34 4.0 1.154 0.953 1.083 0.946 A 59.13 A Example 3-4 85 2.7 5 7.3 34 2.7 1.203 0.943 1.121 0.939 A 89.75 A Example 3-5 40 2.7 44 13.3 298 2.8 1.133 0.970 1.133 0.977 A 29.35 B Example 3-6 50 2.7 44 3.3 298 1.7 1.209 0.959 1.200 0.969 A 35.91 B Example 3-7 54 3 11 32 75 7.1 0.997 0.986 0.969 0.974 B 35.08 B Example 3-8 60 3 11 26 75 6.3 1.047 0.977 1.010 0.967 A 39.06 B Example 3-9 38 3 21.5 37.5 146 6.8 0.971 0.993 0.959 0.983 A 30.44 B Example 3-10 40 3 21.5 35.5 146 6.6 0.986 0.990 0.972 0.981 A 30.89 B Example 3-11 45 3 21.5 30.5 146 6.1 1.025 0.984 1.005 0.976 A 33.03 B Example 3-12 50 3 21.5 25.5 146 5.5 1.064 0.977 1.039 0.970 A 35.61 B Example 313 55 3 21.5 20.5 146 4.7 1.105 0.970 1.073 0.965 A 39.71 B Example 3-14 60 3 21.5 15.5 146 3.9 1.147 0.963 1.108 0.960 A 45.73 A Example 3-15 30 3 29 38 197 6.1 0.971 0.994 0.968 0.987 A 28.48 B Example 3-16 40 3 29 28 197 5.2 1.046 0.982 1.033 0.978 A 31.63 B Example 3-17 50 3 29 18 197 4.0 1.124 0.969 1.101 0.968 A 37.48 B Example 3-18 30 3 36 31 244 4.9 1.020 0.987 1.020 0.985 A 28.63 B Example 3-19 40 3 36 21 244 4.0 1.094 0.975 1.086 0.976 A 32.24 B Example 3-20 50 3 36 11 244 2.8 1.171 0.963 1.153 0.968 A 38.92 B Example 3-21 30 3 44 23 298 3.8 1.067 0.981 1.075 0.985 A 28.67 B Example 3-22 40 3 44 13 298 2.9 1.140 0.970 1.140 0.976 A 32.41 B Example 3-23 45 3.5 21.5 30 146 6.2 1.038 0.983 1.017 0.974 A 38.35 B Example 3-24 50 3.5 21.5 25 146 5.6 1.077 0.976 1.050 0.969 A 41.68 B Example 3-25 55 3.5 21.5 20 146 4.8 1.118 0.969 1.085 0.964 A 46.43 A Example 3-26 60 3.5 21.5 15 146 4.0 1.161 0.962 1.119 0.958 A 53.73 A

[0192] Table 20 HFO-1123 <![CDATA[CO 2 > HFC-32 HFO-1234yf GWP TG Pc Pc / Pe CAP COP Equation (1) Degree of concentration reduction Evaluation Examples 3-27 55 4 11 30 75 7.3 1.033 0.983 1.000 0.969 B 47.11 A Examples 3-28 60 4 11 25 75 6.6 1.075 0.975 1.035 0.963 A 51.86 A Examples 3-29 42 4 21.5 32.5 146 6.7 1.027 0.987 1.009 0.976 A 42.11 B Examples 3-30 45 4 21.5 29.5 146 6.4 1.051 0.983 1.028 0.973 A 43.83 B Examples 3-31 50 4 21.5 24.5 146 5.7 1.091 0.975 1.062 0.967 A 47.65 A Examples 3-32 55 4 21.5 19.5 146 4.9 1.132 0.968 1.096 0.962 A 53.20 A Examples 3-33 60 4 21.5 14.5 146 4.1 1.174 0.960 1.131 0.957 A 61.77 A Examples 3-34 30 4 29 37 197 6.5 0.997 0.993 0.991 0.984 A 37.82 B Examples 3-35 40 4 29 27 197 5.5 1.071 0.981 1.056 0.975 A 42.12 B Examples 3-36 50 4 29 17 197 4.2 1.150 0.967 1.124 0.965 A 50.24 A Examples 3-37 30 4 36 30 244 5.2 1.044 0.986 1.043 0.982 A 37.75 B Examples 3-38 40 4 36 20 244 4.2 1.119 0.975 1.109 0.974 A 42.77 B Examples 3-39 50 4 36 10 244 3.0 1.197 0.961 1.176 0.965 A 51.97 A Examples 3-40 30 4 44 22 298 4.1 1.092 0.981 1.097 0.982 A 37.98 B Examples 3-41 40 4 44 12 298 3.1 1.165 0.969 1.162 0.974 A 43.03 B Examples 3-42 45 4 44 7 298 1.9 1.241 0.958 1.229 0.965 A 47.07 A Examples 3-43 45 4.5 21.5 29 146 6.5 1.064 0.982 1.040 0.971 A 49.02 A Examples 3-44 50 4.5 21.5 24 146 5.8 1.104 0.975 1.074 0.966 A 53.65 A Examples 3-45 55 4.5 21.5 19 146 5.0 1.145 0.968 1.108 0.961 A 60.01 A Examples 3-46 60 4.5 21.5 14 146 4.2 1.188 0.960 1.143 0.955 A 69.82 A Examples 3-47 55 5 11 29 75 7.6 1.061 0.982 1.025 0.966 B 58.69 A Examples 3-48 60 5 11 24 75 6.8 1.103 0.973 1.059 0.960 A 64.97 A Examples 3-49 45 5 21.5 28.5 146 6.7 1.077 0.982 1.052 0.970 A 54.40 A Examples 3-50 50 5 21.5 23.5 146 5.9 1.117 0.974 1.086 0.964 A 59.34 A Examples 3-51 55 5 21.5 18.5 146 5.1 1.159 0.967 1.120 0.959 A 66.62 A Examples 3-52 60 5 21.5 13.5 146 4.2 1.201 0.959 1.155 0.954 A 78.16 A Examples 3-53 30 5 29 36 197 6.8 1.022 0.992 1.014 0.981 A 46.27 A Examples 3-54 40 5 29 26 197 5.7 1.097 0.979 1.080 0.972 A 51.89 A Examples 3-55 50 5 29 16 197 4.4 1.176 0.966 1.147 0.962 A 62.55 A Examples 3-56 30 5 36 29 244 5.5 1.069 0.985 1.066 0.979 A 46.41 A Examples 3-57 40 5 36 19 244 4.5 1.144 0.974 1.131 0.971 A 52.56 A Examples 3-58 50 5 36 9 244 3.1 1.222 0.960 1.198 0.962 A 64.67 A Examples 3-59 30 5 44 21 298 4.4 1.116 0.979 1.119 0.979 A 46.39 A Examples 3-60 40 5 44 11 298 3.4 1.189 0.968 1.184 0.971 A 52.91 A

[0193] Table 21 HFO-1123 <![CDATA[CO 2 > HFC-32 HFO-1234yf GWP TG Pc Pc / Pe CAP COP Equation (1) Degree of concentration reduction Evaluation Examples 3-61 70 10 5 15 34 7.1 1.276 0.955 1.193 0.935 B 157.35 A Examples 3-62 80 10 5 5 34 4.1 1.372 0.933 1.264 0.923 A 384.45 A Examples 3-63 65 10 11 14 75 6.5 1.293 0.955 1.216 0.937 A 158.41 A Examples 3-64 70 10 11 9 75 5.1 1.339 0.945 1.251 0.931 A 216.07 A Examples 3-65 55 10 21.5 13.5 146 5.8 1.297 0.958 1.239 0.944 A 134.04 A Examples 3-66 60 10 21.5 8.5 146 4.7 1.341 0.949 1.274 0.939 A 167.68 A Examples 3-67 63 10 21.5 5.5 146 3.9 1.367 0.944 1.295 0.937 A 203.25 A Examples 3-68 45 10 29 16 197 6.0 1.270 0.966 1.230 0.952 A 106.69 A Examples 3-69 50 10 29 11 197 5.1 1.310 0.958 1.264 0.947 A 122.13 A Examples 3-70 55 10 29 6 196 4.0 1.351 0.950 1.298 0.943 A 147.93 A Examples 3-71 35 10 36 19 244 6.2 1.235 0.973 1.214 0.960 A 89.12 A Examples 3-72 40 10 36 14 244 5.5 1.274 0.966 1.246 0.956 A 97.29 A Examples 3-73 45 10 36 9 244 4.6 1.313 0.959 1.279 0.952 A 109.07 A Examples 3-74 30 10 44 16 298 5.6 1.241 0.975 1.232 0.964 A 70.01 A Examples 3-75 40 10 44 6 298 4.2 1.315 0.963 1.296 0.956 A 97.35 A Examples 3-76 55 15 21.5 8.5 146 6.0 1.441 0.947 1.359 0.928 A 209.16 A Examples 3-77 30 15 44 11 298 6.4 1.368 0.967 1.344 0.950 A 109.66 A Examples 3-78 30 20 44 6 298 6.8 1.496 0.961 1.454 0.935 A 130.85 A

[0194] As shown in Tables 19 to 21, it can be seen that in Examples 3-1 to 3-78, the cycling performance is excellent and the concentration of HFO-1123 in the gas phase can be suppressed. In particular, in Examples 3-3, 3-5, 3-8 to 3-26, 3-28 to 3-46, 3-48 to 3-60, and 3-62 to 3-77, when the content of HFO-1123 is A mass% with respect to the total content of HFO-1123, carbon dioxide, HFO-32, and HFO-1234yf, the content of carbon dioxide is B mass% with respect to the total content, the content of HFO-32 is C mass% with respect to the total content, and the content of HFO-1234yf is D mass% with respect to the total content, A is 30.0 to 80.0, B is 2.7 to 15.0, C is 5.0 to 45.0, and D satisfies formula (1). Therefore, the temperature gradient reaches 7.0 °C or less and the cycling performance is excellent. In addition, the content of HFO-1123 in Example 3-3 is 80.0 mass% or less, so the COP is higher than that in Example 3-4. The content of HFO-1234yf in Example 3-5 is 5.0 mass% or more, so the condensation pressure is lower than that in Example 3-6. The content of carbon dioxide in Example 3-77 is 15.0 mass% or less, so the condensation pressure is lower than that in Example 3-78.

[0195] [Examples 4-1 to 4-48] In Examples 4-1 to 4-48, for a working medium containing HFO-1123, carbon dioxide, HFC-32, and HFO-1234ze(E) having the compositions (mass%) shown in Tables 22 to 23, the temperature gradient (denoted as "TG" in the table, unit: °C), condensation pressure (denoted as "Pc" in the table), compression ratio (denoted as "Pc / Pe" in the table), CAP, and COP are obtained by performing theoretical calculations of the refrigeration cycle under the above conditions. In Tables 22 to 23, it is denoted as A when formula (2) is satisfied, and B when not satisfied. In addition, the degree of concentration reduction is calculated in the same manner as in Example 1-1. When the degree of concentration reduction is less than 25%, it is evaluated as C, when it is 25% or more and less than 45%, it is evaluated as B, and when it is 45% or more, it is evaluated as A. The GWP is also calculated. The measurement results and evaluation results are shown in Tables 22 to 23.

[0196] Table 22 HFO-1123 <![CDATA[CO 2 > HFC-32 HFO-1234ze(E) GWP TG Pc Pc / Pe CAP COP Equation (2) Degree of concentration reduction Evaluation Examples 4-1 75 3 3 19 21 8.5 1.047 0.988 1.002 0.959 B 41.79 B Examples 4-2 75 3 5 17 34 7.8 1.074 0.982 1.025 0.955 B 44.63 B Examples 4-3 80 3 5 12 34 6.0 1.132 0.968 1.069 0.946 A 57.72 A Examples 4-4 85 3 5 7 34 4.0 1.194 0.952 1.114 0.938 A 89.44 A Examples 4-5 70 3 11 16 75 7.2 1.094 0.980 1.051 0.957 B 45.09 A Examples 4-6 75 3 11 11 75 5.4 1.153 0.966 1.095 0.949 A 58.26 A Examples 4-7 60 3 21.5 15.5 146 6.6 1.105 0.981 1.077 0.963 A 40.02 B Examples 4-8 65 3 21.5 10.5 146 4.9 1.161 0.968 1.121 0.956 A 49.07 A Examples 4-9 70 3 21.5 5.5 146 3.0 1.220 0.953 1.167 0.950 A 68.57 A Examples 4-10 72 3 21.5 3.5 146 2.2 1.243 0.948 1.187 0.948 A 83.55 A Examples 4-11 55 3 29 13 196 5.4 1.128 0.977 1.108 0.966 A 38.33 B Examples 4-12 60 3 29 8 196 3.8 1.184 0.965 1.152 0.960 A 46.45 A Examples 4-13 50 3 36 11 244 4.6 1.140 0.975 1.129 0.970 A 35.87 B Examples 414 55 3 36 6 244 3.1 1.195 0.963 1.174 0.964 A 42.31 B Examples 4-15 40 3 44 13 298 4.9 1.105 0.984 1.112 0.979 A 30.20 B Examples 4-16 45 3 44 8 298 3.6 1.156 0.973 1.156 0.974 A 33.59 B Examples 4-17 70 4 11 15 75 7.2 1.124 0.978 1.076 0.953 B 60.95 A Examples 4-18 80 4 11 5 75 3.2 1.244 0.947 1.167 0.939 A 138.53 A Examples 4-19 60 4 21.5 14.5 146 6.6 1.134 0.979 1.101 0.960 A 53.81 A Examples 4-20 65 4 21.5 9.5 146 4.8 1.190 0.966 1.146 0.953 A 67.51 A Examples 4-21 55 4 29 12 196 5.4 1.157 0.975 1.132 0.963 A 51.36 A Examples 4-22 60 4 29 7 196 3.7 1.212 0.962 1.177 0.957 A 63.34 A Examples 4-23 45 4 36 15 244 6.0 1.116 0.985 1.110 0.972 A 42.22 B Examples 4-24 50 4 36 10 244 4.6 1.168 0.973 1.153 0.967 A 47.86 A Examples 4-25 32 4 44 20 298 6.8 1.053 0.998 1.068 0.986 A 35.57 B Examples 4-26 35 4 44 17 298 6.1 1.082 0.992 1.094 0.982 A 37.06 B Examples 4-27 40 4 44 12 298 4.9 1.132 0.981 1.136 0.976 A 40.16 B Examples 4-28 45 4 44 7 298 3.6 1.183 0.971 1.180 0.971 A 44.71 B

[0197] Table 23 HFO-1123 <![CDATA[CO 2 > HFC-32 HFO-1234ze(E) GWP TG PC Pc / Pe CAP COP Equation (2) Degree of concentration reduction Evaluation Examples 4-29 70 5 11 14 75 7.2 1.154 0.974 1.101 0.949 B 78.03 A Examples 4-30 75 5 11 9 75 5.2 1.213 0.960 1.146 0.942 A 107.64 A Examples 4-31 60 5 21.5 13.5 146 6.6 1.163 0.975 1.126 0.956 A 68.17 A Examples 4-32 65 5 21.5 8.5 146 4.7 1.220 0.962 1.171 0.950 A 87.09 A Examples 4-33 55 5 29 11 196 5.4 1.185 0.972 1.156 0.959 A 64.71 A Examples 4-34 60 5 29 6 196 3.7 1.241 0.959 1.202 0.954 A 81.08 A Examples 4-35 45 5 36 14 244 6.1 1.143 0.982 1.134 0.969 A 52.31 A Examples 4-36 50 5 36 9 244 4.6 1.196 0.971 1.178 0.963 A 59.68 A Examples 4-37 35 5 44 16 298 6.3 1.109 0.990 1.117 0.979 A 45.35 A Examples 4-38 40 5 44 11 298 5.0 1.159 0.980 1.160 0.973 A 49.43 A Examples 4-39 75 10 5 10 34 7.4 1.294 0.959 1.206 0.929 B 185.58 A Examples 4-40 80 10 5 5 34 5.0 1.356 0.941 1.253 0.923 A 336.47 A Examples 4-41 60 10 21.5 8.5 146 6.2 1.314 0.961 1.253 0.939 A 148.95 A Examples 4-42 55 10 29 6 196 5.1 1.332 0.958 1.282 0.943 A 136.96 A Examples 4-43 45 10 36 9 244 6.1 1.285 0.971 1.257 0.953 A 101.08 A Examples 4-44 35 10 44 11 298 6.6 1.244 0.980 1.238 0.963 A 83.10 A Examples 4-45 40 10 44 6 298 5.2 1.297 0.969 1.281 0.957 A 93.07 A Examples 4-46 57 15 21.5 6.5 146 6.7 1.435 0.953 1.355 0.927 A 212.39 A Examples 4-47 35 15 44 6 298 6.6 1.385 0.968 1.360 0.947 A 115.29 A Examples 4-48 35 16 44 5 298 6.5 1.414 0.966 1.384 0.944 A 121.32 A

[0198] As shown in Tables 22 to 23, it can be seen that in Examples 4-1 to 4-48, the cycle performance is excellent and the concentration of HFO-1123 in the gas phase can be suppressed. In particular, in Examples 4-3, 4-6 to 4-9, 4-11 to 4-16, 4-18 to 4-28, 4-30 to 38, 4-40 to 4-47, when the content of HFO-1123 is set to E mass % relative to the total content of HFO-1123, carbon dioxide, HFC-32 and HFO-1234ze(E), the content of carbon dioxide is set to F mass % relative to the total content, the content of HFO-32 is set to G mass % relative to the total content, and the content of HFO-1234ze(E) is set to H mass % relative to the total content, E is 30.0 to 80.0, F is 3.0 to 15.0, G is 5.0 to 45.0, and H satisfies formula (2). Therefore, the temperature gradient reaches 7.0 °C or less and the cycle performance is excellent. In Example 4-3, the content of HFO-1123 is 80.0 mass % or less, so the COP is higher than that in Example 4-4. In Example 4-9, the content of HFO-1234ze(E) is 5.0 mass % or more, so the condensation pressure is lower than that in Example 4-10. In Example 4-47, the carbon dioxide content is 15.0 mass % or less, so the condensation pressure is lower than that in Example 4-48.

[0199] In addition, the entire disclosure of Japanese Patent Application No. 2022-171785 filed on October 26, 2022 is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications and technical standards described in this specification are incorporated into this specification by reference to the same extent as if each of the documents, patent applications and technical standards were specifically and separately incorporated by reference.

Claims

1. A working medium for thermal cycle, which comprises trifluoroethylene, a low-boiling compound having a boiling point lower than that of the trifluoroethylene, and a high-boiling compound having a boiling point higher than that of the trifluoroethylene, wherein the low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane, and the high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

2. The working medium for thermal cycle according to claim 1, wherein the content of the trifluoroethylene is 30.0% by mass to 80.0% by mass relative to the total content of the trifluoroethylene, the low-boiling compound, and the high-boiling compound, the content of the low-boiling compound is 2.7% by mass to 60.0% by mass relative to the total content, the content of the high-boiling compound is 10.0% by mass to 67.3% by mass relative to the total content, and the total content of the trifluoroethylene, the low-boiling compound, and the high-boiling compound is 90.0% by mass or more relative to the total amount of the working medium for thermal cycle.

3. The working medium for thermal cycle according to claim 1, wherein the low-boiling compound contains carbon dioxide, the high-boiling compound contains difluoromethane and 2,3,3,3-tetrafluoropropene, when the content of the trifluoroethylene is set as A% by mass relative to the total content of the trifluoroethylene, the carbon dioxide, the difluoromethane, and the 2,3,3,3-tetrafluoropropene, the content of the carbon dioxide is set as B% by mass relative to the total content, the content of the difluoromethane is set as C% by mass relative to the total content, and the content of the 2,3,3,3-tetrafluoropropene is set as D% by mass relative to the total content, A is 30.0 to 80.0, B is 2.7 to 60.0, C is 5.0 to 45.0, D is 5.0 to 62.

3.

4. The working medium for thermal cycle according to claim 3, wherein A is 30.0 to 80.0, B is 2.7 to 15.0, C is 5.0 to 45.0, D satisfies the following formula (1): 5.0 ≤ D ≤ (0.000003B 2 −0.00053B + 0.00616) × A 2 +(−0.00013B 2 + 0.07589B − 1.09581) × A + (0.05608 × B 2 − 5.19457B + 79.27652).

5. The working medium for thermal cycle according to claim 1, wherein the low-boiling compound contains carbon dioxide, the high-boiling compound contains difluoromethane and (E)-1,3,3,3-tetrafluoropropene when the content of the trifluoroethylene is set as E% by mass relative to the total content of the trifluoroethylene, the carbon dioxide, the difluoromethane, and the (E)-1,3,3,3-tetrafluoropropene, the content of the carbon dioxide is set as F% by mass relative to the total content, the content of the difluoromethane is set as G% by mass relative to the total content, and the content of the (E)-1,3,3,3-tetrafluoropropene is set as H% by mass relative to the total content, E is 30.0 to 80.0, F is 3.0 to 60.0, G is 5.0 to 45.0, H is 5.0 to 62.

0.

6. The working medium for thermal cycling according to claim 5, wherein, E is 30.0 to 80.0, F is 3.0 to 15.0, G is 5.0 to 45.0, H satisfies the following formula (2): 5.0 ≤ H ≤ (0.000005F 2 −0.00037F + 0.00301)×E 2 +(−0.00087F 2 + 0.05802F − 0.54609)E + (0.05969F 2 − 3.39263F + 41.55565)。 7. A composition for a thermal cycling system, comprising the working medium for thermal cycling according to any one of claims 1 to 6 and a refrigeration oil.

8. The composition for a thermal cycling system according to claim 7, wherein, the refrigeration oil is at least one selected from polyalkylene glycol oils, polyol ester oils, polyethylene ether oils, fluorinated oils, mineral oils, and hydrocarbon synthetic oils.

9. A method for storing a working medium for thermal cycling, which includes a step of storing a working medium for thermal cycling containing trifluoroethylene, a low-boiling compound having a boiling point lower than that of the trifluoroethylene, and a high-boiling compound having a boiling point higher than that of the trifluoroethylene, the low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane, the high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

10. A method for manufacturing a working medium for thermal cycling, which includes a step of mixing trifluoroethylene, a low-boiling compound having a boiling point lower than that of the trifluoroethylene, and a high-boiling compound having a boiling point higher than that of the trifluoroethylene, the low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane, the high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

11. A storage container for a working medium for thermal cycling, which is a closed storage container for storing a working medium for thermal cycling containing trifluoroethylene, a low-boiling compound having a boiling point lower than that of the trifluoroethylene, and a high-boiling compound having a boiling point higher than that of the trifluoroethylene in a state where the gas phase and the liquid phase coexist, the low-boiling compound is at least one selected from carbon dioxide, hexafluoroethane, and fluoromethane, the high-boiling compound is at least two selected from difluoromethane, 2,3,3,3-tetrafluoropropene, (E)-1,3,3,3-tetrafluoropropene, 3,3,3-trifluoropropene, tetrafluoromethane, 1,1,2,2-tetrafluoroethane, 1,1,1-trifluoroethane, 1,1,1,2,3,3,3-heptafluoropropane, cyclopropane, isobutene, isobutane, dimethyl ether, and ammonia.

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