Working medium, composition for heat cycle systems, heat cycle system, and heat cycle method

Abstract

Provided is a working medium which contains HFO-1123, HFO-1234yf, and carbon dioxide, wherein: X and Y satisfy formulae (A1) and (A2) described below, where X mass% is the content of carbon dioxide and Y mass% is the content of HFO-1123 with respect to the total content of the components; and the total content of HFO-1123, HFO-1234yf, and carbon dioxide is 99.0 mass% or more with respect to the total amount of the working medium. Also provided are a composition for heat cycle systems, a heat cycle system, and a heat cycle method, each of which uses the working medium. (A1): -2.20X + 25.60 ≤ Y ≤ -5.58X + 61.74 (A2): 2.5 ≤ X ≤ 6.0

Description

Working fluid, composition for heat cycle system, heat cycle system, and heat cycle method

[0001] The present disclosure relates to a working fluid, a composition for a heat cycle system, a heat cycle system, and a heat cycle method.

[0002] It has been pointed out that working fluids such as refrigerants for refrigeration and freezing equipment, refrigerants for air conditioning equipment, working fluids for heating and hot water supply equipment, working fluids for power generation systems (such as waste heat recovery power generation), working fluids for latent heat transport devices (such as heat pipes), and working fluids for heat cycles such as secondary cooling fluids have had an impact on the stratospheric ozone layer and global warming. For example, R404A, R410A, R407C, difluoromethane (R32), and the like used in cooling systems have a high global warming potential (GWP), and therefore alternatives are being considered.

[0003] Patent Document 1 describes a working fluid for a heat cycle containing trifluoroethylene (HFO-1123) and a first component consisting of at least one substance selected from carbon dioxide, fluoromethane, trifluoroiodomethane, methane, ethane, propane, helium, neon, argon, krypton, xenon, nitrogen, and ammonia.

[0004] International Publication No. 2016 / 194847

[0005] When using azeotropic and non-azeotropic mixtures of working fluids containing low GWP working fluids such as HFO-1123 instead of conventional working fluids such as R404A, the boiling point of the working fluid differs from that of conventional working fluids, resulting in changes in saturated vapor pressure and saturated liquid pressure within the operating temperature range of the heat cycle system. Therefore, if the pressure range within the equipment during operation of the heat cycle system differs significantly from that when conventional working fluids are used, it may become necessary to reconsider the pressure-resistant design of the equipment, or cycle performance and equipment reliability may be reduced in operating environments requiring operation at low temperatures. Therefore, even when using an alternative working fluid, it is desirable to be able to operate the heat cycle system within the same pressure range as that of conventional working fluids.

[0006] One embodiment of the present disclosure relates to providing a working fluid having a saturated vapor pressure that is not too low in a low-temperature environment and a saturated liquid pressure that is not too high in a high-temperature environment, as well as a composition for a heat cycle system, a heat cycle system, and a heat cycle method that use the working fluid.

[0007] The present disclosure includes the following aspects. <1> A working fluid comprising trifluoroethylene, 2,3,3,3-tetrafluoropropene, and carbon dioxide, wherein, when the content of the carbon dioxide relative to the total content of the trifluoroethylene, the 2,3,3,3-tetrafluoropropene, and the carbon dioxide is X% by mass, and the content of the trifluoroethylene relative to the total content of the trifluoroethylene, the 2,3,3,3-tetrafluoropropene, and the carbon dioxide is Y% by mass, X and Y satisfy the following formulas (A1) and (A2), and the total content of the trifluoroethylene, the 2,3,3,3-tetrafluoropropene, and the carbon dioxide is 99.0% by mass or more based on the total amount of the working fluid. -2.20X + 25.60≦Y≦-5.58X + 61.74 (A1) 2.5≦X≦6.0 (A2) <2> The working fluid according to <1>, wherein X and Y further satisfy the following formula (A3): -2.20X + 25.60≦Y≦-5.67X + 56.20 ... (A3) <3> The working fluid according to <1> or <2>, wherein X is 3.0 to 4.0. <4> The working fluid according to any one of <1> to <3>, wherein Y is 25.0 to 40.0. <5> The working fluid according to any one of <1> to <4>, wherein a quantity of heat of combustion is 10.310 MJ / kg or less. <6> A composition for a heat cycle system, comprising the working fluid according to any one of <1> to <5>, and a refrigerating machine oil. <7> The composition for a heat cycle system according to <6>, wherein the refrigerating machine oil contains at least one selected from the group consisting of polyalkylene glycol (PAG), polyol ester (POE), and polyvinyl ether (PVE). <8> A heat cycle system comprising: the working fluid according to any one of <1> to <5>, or the composition for a heat cycle system according to <6> or <7>; a compressor that compresses vapor of the working fluid; a condenser that cools and liquefies the vapor of the working fluid discharged from the compressor; a pressure reducing device that reduces the pressure of the working fluid discharged from the condenser; and an evaporator that heats the working fluid discharged from the pressure reducing device, wherein the evaporator controls the evaporation temperature of the working fluid to −40° C. or higher.<9> The heat cycle system according to <8>, wherein the evaporator controls the evaporation temperature of the working fluid to -35°C or higher. <10> The heat cycle system according to <8> or <9>, wherein the evaporator controls the evaporation temperature of the working fluid to -30°C or higher. <11> A heat cycle method comprising compressing vapor of the working fluid according to any one of <1> to <5>, cooling the vapor of the working fluid to liquefy it, depressurizing the liquefied working fluid, and heating the depressurized working fluid at an evaporation temperature of -40°C or higher. <12> The heat cycle method according to <11>, wherein the depressurized working fluid is heated at an evaporation temperature of -35°C or higher. <13> The heat cycle method according to <11> or <12>, wherein the depressurized working fluid is heated at an evaporation temperature of -30°C or higher.

[0008] According to one embodiment of the present disclosure, there are provided a working fluid having a saturated vapor pressure that is not too low in a low-temperature environment and a saturated liquid pressure that is not too high in a high-temperature environment, as well as a composition for a heat cycle system, a heat cycle system, and a heat cycle method that use the working fluid.

[0009] 1 is a schematic diagram showing an example of a refrigeration cycle device; 2 is a cycle diagram showing the state change of an example of a working medium in a refrigeration cycle device on a pressure-enthalpy diagram; 3 is a diagram showing the saturated liquid pressure and saturated vapor pressure of an example of a single medium and an azeotropic mixed medium on a pressure-enthalpy diagram; and 4 is a diagram showing the saturated liquid pressure and saturated vapor pressure of an example of a non-azeotropic mixed medium on a pressure-enthalpy diagram.

[0010] In the present disclosure, a numerical range indicated using "to" means a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In the numerical ranges described in stages in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the Examples. In the present disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In the present disclosure, when multiple substances corresponding to each component are present, the amount of each component refers to the total amount of the multiple substances unless otherwise specified. In the present disclosure, pressure refers to absolute pressure, and is 0.101 MPa at atmospheric pressure. In the present disclosure, saturated vapor pressure means the pressure of saturated vapor, and refers to the pressure at the intersection of an isotherm and a saturated vapor line on a pressure-enthalpy diagram. In the present disclosure, saturated liquid pressure means the pressure of saturated liquid, and refers to the pressure at the intersection of an isotherm and a saturated liquid line on a pressure-enthalpy diagram. Fig. 3 is a diagram showing the saturated liquid pressure and saturated vapor pressure of an example of a single medium and an azeotropic medium mixture on a pressure-enthalpy diagram, and Fig. 4 is a diagram showing the saturated liquid pressure and saturated vapor pressure of an example of a non-azeotropic medium mixture on a pressure-enthalpy diagram. As shown in Fig. 3, when the working medium is a single medium or an azeotropic medium mixture, the saturated liquid pressure and saturated vapor pressure at the same temperature, as indicated by the isotherms, are substantially the same. On the other hand, as shown in Fig. 4, when the working medium is a non-azeotropic medium mixture, the saturated vapor pressure and saturated liquid pressure at the same temperature, as indicated by the isotherms, are different, and the saturated vapor pressure is lower than the saturated liquid pressure.

[0011] The working fluid of the present disclosure comprises trifluoroethylene (HFO-1123), 2,3,3,3-tetrafluoropropene (HFO-1234yf), and carbon dioxide, wherein, when the content of carbon dioxide relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide is X% by mass and the content of HFO-1123 relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide is Y% by mass, X and Y satisfy the following formulas (A1) and (A2), and the total content of HFO-1123, HFO-1234yf, and carbon dioxide is 99.0% by mass or more based on the total amount of the working fluid: −2.20X+25.60≦Y≦−5.58X+61.74 (A1) 2.5≦X≦6.0 (A2)

[0012] The working fluid of the present disclosure has a saturated vapor pressure that is not too low in a low-temperature environment (e.g., −40° C.) and a saturated liquid pressure that is not too high in a high-temperature environment (e.g., 55° C.), thereby enabling the operation of a heat cycle system in a pressure range similar to that of conventional working fluids.

[0013] Although HFO-1123 has a low GWP, it is classified as mildly flammable (equivalent to 2 L) in ASHRAE Standard 34, and has a relatively low boiling point of -61.239°C, resulting in higher saturated vapor pressure and saturated liquid pressure than conventional working fluids such as R404A. Therefore, when HFO-1123 is used alone, it becomes necessary to change the pressure-resistant design of equipment that uses conventional working fluids. Although HFO-1234yf has a low GWP, it is classified as mildly flammable (equivalent to 2 L) in ASHRAE Standard 34, and has a relatively high boiling point of -29.485°C. Therefore, in an operating environment requiring operation at a low evaporation temperature, the low-pressure side of the equipment falls below the boiling point, resulting in negative pressure operation, which tends to reduce the intake of working fluid into the compressor and reduce cycle performance and equipment reliability. Carbon dioxide has a low GWP and is classified as non-flammable (1) in ASHRAE Standard 34. However, because its boiling point is relatively low at -78.464°C, when a working fluid containing a large amount of carbon dioxide is used, it becomes necessary to change the pressure-resistant design of equipment that uses conventional working fluids. In response to this, the present inventors have discovered that by mixing HFO-1123, HFO-1234yf, and carbon dioxide in a specific ratio and setting the total content of HFO-1123, HFO-1234yf, and carbon dioxide to 99.0 mass% or more of the working fluid, a working fluid can be obtained that has a saturated vapor pressure that is not too low in a low-temperature environment (e.g., -40°C) and a saturated liquid pressure that is not too high in a high-temperature environment (e.g., 55°C). Furthermore, because the working fluid of the present disclosure contains carbon dioxide in a specific ratio, flammability can also be effectively suppressed. In addition, since HFO-1123, HFO-1234yf, and carbon dioxide all have low GWP, a working fluid with low GWP can be obtained by mixing these.

[0014] The table below shows the boiling points, GWP, ASHRAE Standard 34 combustion classifications, and combustion heat values ​​of conventional working fluids R410A, R404A, and R32, as well as HFO-1123, HFO-1234yf, and carbon dioxide.

[0015]

[0016] Patent Document 1 does not describe a working fluid containing HFO-1123, HFO-1234yf, and carbon dioxide, in which X and Y satisfy formulas (A1) and (A2), and the total content of HFO-1123, HFO-1234yf, and carbon dioxide is 99.0 mass% or more based on the total amount of the working fluid.

[0017] In the present disclosure, the term "working fluid" refers to a medium that transfers heat, and is a concept that encompasses refrigerant compositions and heat transfer medium compositions. The refrigerant composition is a medium that primarily serves to cool a heat source, but may also be used as a medium that simultaneously serves to heat the heat source. The heat transfer medium composition is a medium that primarily serves to heat the heat source, but may also be used as a medium that simultaneously serves to cool the heat source. The working fluid is preferably used for a heat cycle. Specifically, the working fluid is preferably used in a heat cycle system in which a series of changes occurs, such as a change in state using heat absorption and heat release, and then a return to the initial state.

[0018] The working fluid of the present disclosure contains HFO-1123, HFO-1234yf, and carbon dioxide. The content of components other than HFO-1123, HFO-1234yf, and carbon dioxide is preferably low, from the viewpoint of reducing the possibility of affecting the GWP of the working fluid. From the above viewpoints, the total content of HFO-1123, HFO-1234yf, and carbon dioxide in the working fluid is 99.0 mass% or more, and preferably 99.5 mass% or more, based on the total amount of the working fluid. The upper limit of the total content of HFO-1123, HFO-1234yf, and carbon dioxide is not particularly limited, and may be 100 mass%. Each component contained in the working fluid will be described in detail below.

[0019] (HFO-1123, Carbon Dioxide) In the working fluid of the present disclosure, when the content of carbon dioxide relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide is X% by mass and the content of HFO-1123 relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide is Y% by mass, X and Y satisfy the following formulas (A1) and (A2): −2.20X+25.60≦Y≦−5.58X+61.74 (A1) 2.5≦X≦6.0 (A2)

[0020] When X and Y satisfy the formulas (A1) and (A2), the saturated vapor pressure at -40°C is approximately 0.082 MPa or more. Therefore, even at a low temperature of -40°C, deterioration of cycle performance and equipment reliability can be suppressed. Furthermore, when X and Y satisfy the formulas (A1) and (A2), the saturated liquid pressure at 55°C is approximately 3.150 MPa or less. This saturated liquid pressure is approximately 1.219 times or less compared to R404A, making it possible to operate a heat cycle system without significantly changing the pressure-resistant design of existing equipment. In addition, the working fluid of the present disclosure contains 2.5% by mass or more of carbon dioxide relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide, thereby effectively reducing flammability.

[0021] It is preferable that X and Y further satisfy the following formula (A3): −2.20X+25.60≦Y≦−5.67X+56.20 (A3).

[0022] When X and Y further satisfy formula (A3), the saturated liquid pressure at 55°C becomes approximately 3.000 MPa or less. This saturated liquid pressure is approximately 1.160 times or less compared to R404A, making it possible to operate a heat cycle system without significantly changing the pressure-resistant design of existing equipment.

[0023] The content (X) of carbon dioxide relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide is 2.5% by mass or more, and from the viewpoint of preventing an excessive decrease in saturated vapor pressure and reducing the flammability of the working fluid, preferably 3.0% by mass or more. The content (X) is 6.0% by mass or less, and from the viewpoint of preventing an excessive increase in saturated liquid pressure, more preferably 5.0% by mass or less, and even more preferably 4.0% by mass or less. From these viewpoints, the content (X) is 2.5 to 6.0% by mass, preferably 2.5 to 5.0% by mass, and more preferably 3.0 to 4.0% by mass.

[0024] The content (Y) of HFO-1123 relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide is preferably 10.0% by mass or more, more preferably 20.0% by mass or more, and even more preferably 25.0% by mass or more, from the viewpoint of preventing an excessive decrease in saturated vapor pressure. From the viewpoint of preventing an excessive increase in saturated liquid pressure, the content (Y) is preferably 50.0% by mass or less, more preferably 45.0% by mass or less, and even more preferably 40.0% by mass or less. From such viewpoints, the content (Y) is preferably 10.0 to 50.0% by mass, more preferably 20.0 to 45.0% by mass, and even more preferably 25.0 to 40.0% by mass.

[0025] (HFO-1234yf) In the working fluid, the content of HFO-1234yf is not particularly limited, and is appropriately adjusted so that the contents of HFO-1123 and carbon dioxide satisfy formulas (A1) and (A2) and the total content of HFO-1123, HFO-1234yf, and carbon dioxide is 99.0% by mass or more. For example, the content of HFO-1234yf relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide may be 44% by mass or more, 50% by mass or more, or even 56% by mass or more. Furthermore, the content of HFO-1234yf relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide may be 87.5% by mass or less, 77.5% by mass or less, or 72% by mass or less. The content may be 44 to 87.5% by mass, 50 to 77.5% by mass, or 56 to 72% by mass.

[0026] (Other Components) The working fluid may or may not contain other components other than HFO-1123, HFO-1234yf, and carbon dioxide. Examples of other components include hydrofluoroolefins (HFOs) other than HFO-1123 and HFO-1234yf, hydrochlorofluoroolefins (HCFOs), hydrofluorocarbons (HFCs), chlorofluoroolefins (CFOs), other halogenated compounds, hydrocarbons, etc. The other components may be one type only, or two or more types.

[0027] Examples of HFOs include 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), (Z)-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), (E)-1 , 3,3,3-tetrafluoropropene (HFO-1234ze(E)), 1,2,3,3,3-pentafluoropropene (HFO-1225ye), 3,3,3-trifluoropropene (HFO-1243zf), (Z)-1,1,1,4,4,4-hexafluorobutene (HFO-1336mzz(Z)), and (E)-1,1,1,4,4,4-hexafluorobutene (HFO-1336mzz(E)).

[0028] Examples of HCFOs include (E) 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(E)), (Z) 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)), 2-chloro-1,1,3,3-tetrafluoropropene (HCFO-1224xc), 2-chloro-1,3,3,3-tetrafluoropropene (HCFO-1224xe), 1-chloro-1,1-difluoroethylene (HCFO-1 122), 1-chloro-1,2-difluoroethylene (HCFO-1122a), (E)-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)), (Z)-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(Z)), 2-chloro-1,1,3-trifluoropropene (HCFO-1233xc), and 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf).

[0029] HFCs include difluoromethane (HFC-32), fluoroethane (HFC-161), 1,1-difluoroethane (HFC-152a), 1,1,1-trifluoroethane (HFC-143a), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane (HFC-134a), pentafluoroethane (HFC-125), and 1,1,1,3,3-pentafluoropropane. Examples of fluorofluoroethanes include pentafluoropropanes such as 1,1,2,2,3,3-hexafluoropropane (HFC-236fa), hexafluoropropanes such as 1,1,2,2,3,3-hexafluoropropane (HFC-236fa), pentafluorobutanes such as 1,1,1,3,3-pentafluorobutane (HFC-365mfc), and heptafluorocyclopentanes such as 1,1,2,2,3,3,4-heptafluorocyclopentane (HFC-c447ef).

[0030] Chlorofluoroolefins (CFOs) include 1,1-dichloro-2,3,3,3-tetrafluoropropene (CFO-1214ya), 1,3-dichloro-1,2,3,3-tetrafluoropropene (CFO-1214yb), and 1,2-dichloro-1,2-difluoroethylene (CFO-1112).

[0031] Other halogenated compounds include monoiodomethane (CH ３ I), diiodomethane (CH ２ I ２ ), dibromomethane (CH ２ Br ２ ), bromomethane (CH ３ Br), dichloromethane (CH ２ Cl ２ ), chloroiodomethane (CH ２ ClI), dibromochloromethane (CHBr ２ Cl), tetraiodomethane (Cl ４ ), carbon tetrabromide (CBr ４ ), bromotrichloromethane (CBrCl ３ ), dibromodichloromethane (CBr ２ Cl ２ ), tribromofluoromethane (CBr ３ F), fluoroiodomethane (CHFI２ ), difluoroiodomethane (CHF ２ I), difluorodiiodomethane (CF ２ I ２ ), dibromodifluoromethane (CBr ２ F ２ ), trifluoroiodomethane (CF ３ I), 1,1,1-trifluoroiodoethane (CF ３ CH ２ Iodine- and bromine-containing compounds such as I).

[0032] Hydrocarbons include propane (R290), cyclopropane, butane, isobutane, pentane, and isopentane.

[0033] When the working fluid of the present disclosure contains other components besides HFO-1123, HFO-1234yf, and carbon dioxide, the total content of the other components is 1.0 mass% or less, preferably 0.5 mass% or less, and may be 0 mass% based on the total amount of the working fluid. Furthermore, when two or more types of other components are contained, the content of each of the other components is less than 1.0 mass% and preferably 0.5 mass% or less.

[0034] The water content in the working fluid, as measured by Karl Fischer coulometric titration, is preferably 20 ppm by mass or less, and more preferably 15 ppm by mass or less, relative to the total amount of the working fluid. A water content of 20 ppm by mass or less suppresses freezing in capillary tubes, which are an example of pressure reducing devices in thermal cycle systems, hydrolysis of the working fluid and refrigerating oil, material deterioration due to acid components generated in the device, generation of contaminants, and the like.

[0035] The air content in the gas phase of the working fluid at 25°C, as measured by gas chromatography, is preferably less than 15,000 ppm by volume, more preferably 8,000 ppm by volume or less. When the air content is less than 15,000 ppm by volume, poor heat transfer in the condenser and evaporator and an increase in operating pressure are suppressed. In particular, reaction of oxygen in the air with the working fluid or refrigeration oil and decomposition thereof are suppressed.

[0036] The working fluid may contain unavoidable components such as impurities by-produced during production and solvents used during production. From the viewpoint of ensuring stability, the total content of these unavoidable components is preferably 1.0 mass% or less, more preferably 0.5 mass% or less, and even more preferably 0.1 mass% or less, based on the total amount of the working fluid. From the viewpoint of simplifying the purification step in the production of the working fluid, the total content of the unavoidable components may be 50.0 mass ppm or more, or may be 100.0 mass ppm or more.

[0037] Inevitable components 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), difluoromethane (HFC-32), fluoromethane (HFC-41), pentafluoroethane (HFC-125), 1,1,2,2-tetrafluoroethane (HFC-1 34), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,2-trifluoroethane (HFC-143), 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), (E)-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), (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-1113), tetrafluoroethylene (FO-1114), hexafluoropropene (FO-1216), perfluorocyclobutane, and the like.

[0038] The working fluid of the present disclosure is dichlorodifluoromethane (R12), chlorodifluoromethane (R22), difluoromethane (R32), tetrafluoroethane (R134a), R404A, R407A, R407C, R407F, R407H, R410A, R413A, R417A, R422A, R422B, R422C, R422D, R423A, R424A, R426A, R R427A, R430A, R434A, R437A, R438A, R448A, R449A, R449B, R449C, R452A, R452B, R454A, R454B, R454C, R455A, R465A, R502, R507, R513A, R1234yf, or (E)-1,3,3,3-tetrafluoropropene (R1234ze(E)). Among these, the working fluid of the present disclosure is suitable as a replacement for R12, R22, R32, R134a, R404A, R407C, R407F, R407H, R410A, R448A, R449A, R454C, R455A, R465A, R1234yf, or R1234ze(E). Note that R1234yf is the same as HFO-1234yf.

[0039] In particular, the working fluid of the present disclosure is suitable as a replacement for the currently widely used R404A, R407C, or R410A. Furthermore, the working fluid of the present disclosure has a saturated vapor pressure of about 1.219 or less at 55°C relative to R404A. Furthermore, the saturated vapor pressure of the working fluid of the present disclosure is about 0.915 or less at 55°C relative to R410. The working fluid used in the heat cycle system of the present disclosure is particularly suitable as a replacement for R404A or R410A.

[0040] The working fluid is used in a refrigeration cycle device in which the evaporation temperature is controlled to, for example, -40°C or higher, preferably -35°C or higher, more preferably -30°C or higher.

[0041] <Global Warming Potential (GWP)> In the present disclosure, GWP is the 100-year value from the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6) unless otherwise specified. The GWP of a mixture is a weighted average by composition mass. The GWP of the working fluid of the present disclosure is preferably less than 1.

[0042] <Combustion Heat> The combustion heat per mass (MJ / kg) is defined by the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE) Standard 34 as an index for determining the flammability of a refrigerant. This standard defines a substance with a calorific value of 19,000 MJ / kg or greater as a "highly flammable" refrigerant. The combustion heat is expressed as the difference between the sum of the enthalpies of formation of the products in the combustion reaction and the enthalpies of formation of the compounds in the reaction system. Formation enthalpies are described in chemistry handbooks, international standards (see Reference A), various handbooks, etc. The formation enthalpies of new compounds can be calculated using Benson's group additivity rule (see Reference B) or computational chemistry techniques. The combustion reaction equations for halogen-containing compounds are also defined in international standards (see References A and C). Reference A: ANSI / ASHRAE Standard 34 (2016), Designation and Safety Classification of Refrigerants. Reference B: S. Benson, Thermochemical Kinetics, 2nd Ed., Wiley Interscience, New York (1976). Reference C: ISO 817 (2014), Refrigerant: Designation and Safety Classification. In this standard, the heat of combustion is considered positive for exothermic reactions.

[0043] In this disclosure, the calorific value of combustion of a working fluid is a theoretical value calculated under the following assumptions: the value of the calorific value of combustion obtained by completely combusting 1 mole of working fluid with oxygen stoichiometrically is converted to the value of the calorific value of combustion per kg of working fluid. The compounds in the product and reaction systems are assumed to be gases. The combustion products are HF (g), CO ２ (g) COF ２ (g) and H ２ If nitrogen and iodine are part of the molecular structure of the substance, the combustion products are N ２ (g) or I ２(g) is added. When calculating the combustion heat of the working fluid, each compound contained in the working fluid is decomposed into the atoms that make up each compound, and a virtual substance containing each atom is set taking into account the molar ratio in the working fluid. The combustion heat is calculated using the combustion reaction formula of the virtual substance. Note that C in the following formula ｑ H ｒ F ｓ For example, the combustion reaction formula is defined by the number of H atoms (r) and the number of F atoms (s) in a substance, and the combustion reaction formula used when the number of H atoms (r) is greater than or equal to the number of F atoms (s) is as follows:

[0044] On the other hand, when the number of H atoms (r) is smaller than the number of F atoms (s), the following combustion reaction formula is used:

[0045]

[0046] The combustion heat quantity of the working fluid is preferably 10.310 MJ / kg or less, and more preferably 10.260 MJ / kg or less.

[0047] <Saturated Vapor Pressure> The saturated vapor pressure is determined using the National Institute of Science and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10.0). The same applies to the saturated liquid pressure, cycle performance, discharge temperature, condensation pressure, evaporation pressure, and refrigeration effect described below. When the working fluid is a single medium or an azeotropic mixture, the saturated liquid pressure and saturated vapor pressure at the same temperature are substantially the same. On the other hand, when the working fluid is a non-azeotropic mixture, the saturated vapor pressure and saturated liquid pressure at the same temperature are different, and the saturated vapor pressure is lower than the saturated liquid pressure. The saturated vapor pressure of the working fluid is preferably 0.082 MPa or higher, more preferably 0.104 MPa or higher, and even more preferably 0.130 MPa or higher, within the operating temperature range of the heat cycle system. From the viewpoint of achieving a saturated vapor pressure of 0.082 MPa or higher, the evaporation temperature is preferably −40°C or higher, more preferably −40 to 15°C. From the viewpoint of achieving a saturated vapor pressure of 0.104 MPa or more, the evaporation temperature is preferably −35° C. or more, and more preferably −35 to 15° C. From the viewpoint of achieving a saturated vapor pressure of 0.130 MPa or more, the evaporation temperature is preferably −30° C. or more, and more preferably −30 to 15° C.

[0048] <Saturated liquid pressure> When the working fluid is a single medium or an azeotropic mixture of mediums, the saturated liquid pressure and the saturated vapor pressure at the same temperature are substantially the same. On the other hand, when the working fluid is a non-azeotropic mixture of mediums, the saturated liquid pressure and the saturated vapor pressure at the same temperature are different, and the saturated liquid pressure is higher than the saturated vapor pressure. The saturated liquid pressure of the working fluid at 55°C is preferably 3.150 MPa or less, more preferably 3.100 MPa or less, and even more preferably 3.000 MPa or less.

[0049] <Cycle Performance> The cycle performance, which is a property required when applying a working fluid to a thermal cycle system, can be evaluated by the coefficient of performance (also referred to as "COP" in this disclosure) and the capacity per unit volume (suction volume of the compressor) (also referred to as "CAP" in this disclosure). When the thermal cycle system is a refrigeration cycle system, the capacity is the refrigeration capacity. The COP and CAP can be calculated by the methods described below.

[0050] In the present disclosure, the cycle performance and the preferred ranges of the discharge temperature, condensation pressure, evaporation pressure, and refrigeration effect shown below are preferred ranges calculated using a refrigeration cycle under the temperature conditions of Condition 1, Condition 2, Condition 3, or Condition 4. In the following description, the preferred ranges for each performance are preferred ranges regardless of whether Condition 1, Condition 2, Condition 3, or Condition 4 is adopted.

[0051] (Condition 1) Condensation temperature: 40°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the condensation start temperature and the condensation end temperature) Evaporation temperature: -40°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the evaporation start temperature and the evaporation end temperature) Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0052] (Condition 2) Condensation temperature: 40°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the condensation start temperature and the condensation end temperature) Evaporation temperature: -20°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the evaporation start temperature and the evaporation end temperature) Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0053] (Condition 3) Condensation temperature: 40°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the condensation start temperature and the condensation end temperature) Evaporation temperature: 0°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the evaporation start temperature and the evaporation end temperature) Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0054] (Condition 4) Condensation temperature: 40°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the condensation start temperature and the condensation end temperature) Evaporation temperature: 15°C (however, in the case of a non-azeotropic mixed medium, this is the average temperature between the evaporation start temperature and the evaporation end temperature) Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0055] The COP of the working fluid is preferably 0.980 or more, more preferably 0.990 or more, and even more preferably 0.995 or more, relative to R404A. There is no particular upper limit to the COP, and a higher COP is more preferable.

[0056] The CAP of the working fluid is preferably 0.780 or more, more preferably 0.800 or more, and even more preferably 0.850 or more, in terms of the ratio to R404A. There is no particular upper limit to the CAP, and a higher CAP is more preferable.

[0057] <Discharge Temperature> When the working fluid is applied to a refrigeration cycle system, the discharge temperature is also an evaluation item. From the viewpoint of extending the life of components of the refrigeration cycle system, the discharge temperature of the working fluid is preferably 140°C or less, more preferably 120°C or less, and even more preferably 110°C or less.

[0058] <Condensation Pressure (Pc)> When applying a working fluid to a refrigeration cycle system, another evaluation item is the condensation pressure (also referred to as "Pc" in the present disclosure). From the viewpoint of pressure-resistant design of the refrigeration cycle system, the condensation pressure of the working fluid is preferably 1.100 or less, more preferably 1.090 or less, and even more preferably 1.080 or less, in terms of R404A ratio. The lower limit of the condensation pressure of the working fluid is not particularly limited, and the condensation pressure may be 0.850 or more, 0.860 or more, or 0.870 or more, in terms of R404A ratio.

[0059] <Evaporation Pressure (Pe)> When applying a working fluid to a refrigeration cycle system, evaporation pressure (also referred to as "Pe" in the present disclosure) is another evaluation item. From the viewpoint of improving the intake of the working fluid into the compressor, the evaporation pressure of the working fluid is preferably 0.680 or more, more preferably 0.700 or more, and even more preferably 0.730 or more, in terms of the ratio to R404A. The upper limit of the evaporation pressure of the working fluid is not particularly limited, and may be 1.100 or less, 1.080 or less, or 1.050 or less, in terms of the ratio to R404A.

[0060] <Refrigeration Effect (Wr)> When a working fluid is applied to a refrigeration cycle system, the refrigeration effect (also referred to as "Wr" in the present disclosure) can be further cited as an evaluation item. The refrigeration effect is the amount of heat (kJ / kg) absorbed per unit weight by the working fluid in the evaporator of the refrigeration cycle system. The refrigeration capacity Q is the value obtained by multiplying Wr by the mass circulation amount of the working fluid. The refrigeration effect of the working fluid is preferably 1.000 or more, more preferably 1.100 or more, and even more preferably 1.150 or more, relative to R404A.

[0061] [Composition for Heat Cycle System] The working fluid of the present disclosure may be used in combination with other components such as a refrigerating machine oil, etc. In one embodiment, the composition for a heat cycle system contains the working fluid of the present disclosure and a refrigerating machine oil.

[0062] (Refrigerating machine oil) As the refrigerating machine oil, any known refrigerating machine oil used in a composition for a heat cycle system can be used. Specific examples of the refrigerating machine oil include oxygen-containing synthetic oils (ester-based refrigerating machine oils, ether-based refrigerating machine oils, etc.), fluorine-based refrigerating machine oils, mineral-based refrigerating machine oils, and hydrocarbon-based synthetic oils.

[0063] Examples of ester-based refrigerating machine oils include dibasic acid ester oils, polyol ester oils, complex ester oils, and polyol carbonate ester oils.

[0064] Preferred dibasic acid ester oils are esters of dibasic acids having 5 to 10 carbon atoms (glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, etc.) with monohydric alcohols having 1 to 15 carbon atoms and a linear or branched alkyl group (methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, etc.). Preferred dibasic acid ester oils are ditridecyl glutarate, di(2-ethylhexyl adipate), diisodecyl adipate, ditridecyl adipate, or di(3-ethylhexyl) sebacate.

[0065] Preferred polyol ester oils are 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 to 20 hydroxyl groups (trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, glycerin, sorbitol, sorbitan, sorbitol-glycerin condensates, etc.) with fatty acids having 6 to 20 carbon atoms (straight-chain or branched fatty acids such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, eicosanoic acid, and oleic acid, or so-called neo acids in which the alpha carbon atom is quaternary). These polyol ester oils may have free hydroxyl groups.

[0066] The polyol ester oil is preferably an ester of a hindered alcohol (neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, etc.), and more preferably trimethylolpropane tripelargonate, pentaerythritol 2-ethylhexanoate, or pentaerythritol tetrapelargonate.

[0067] The complex ester oil is an ester of a fatty acid, a dibasic acid, a monohydric alcohol, and a polyol. The fatty acid, dibasic acid, monohydric alcohol, and polyol may be the same as those described above.

[0068] The polyol carbonate oil is an ester of carbonic acid and a polyol. Examples of the polyol include the same diols and polyols as described above. The polyol carbonate oil may also be a ring-opening polymer of a cyclic alkylene carbonate.

[0069] Examples of ether-based refrigerating machine oils include polyvinyl ether oils and polyoxyalkylene oils.

[0070] Examples of polyvinyl 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. One type of vinyl ether monomer may be used alone, or two or more types may be used in combination.

[0071] Examples of hydrocarbon monomers having an olefinic double bond include ethylene, propylene, various butenes, various pentenes, various hexenes, various heptenes, various octenes, diisobutylene, triisobutylene, styrene, α-methylstyrene, various alkyl-substituted styrenes, etc. One type of hydrocarbon monomer having an olefinic double bond may be used alone, or two or more types may be used in combination.

[0072] The polyvinyl ether copolymer may be either a block copolymer or a random copolymer. The polyvinyl ether oil may be used alone or in combination of two or more kinds.

[0073] Examples of polyoxyalkylene oils include polyoxyalkylene monools, polyoxyalkylene polyols; alkyl ethers of polyoxyalkylene monools or polyoxyalkylene polyols; and esters of polyoxyalkylene monools or polyoxyalkylene polyols.

[0074] Polyoxyalkylene monools and polyoxyalkylene polyols can be produced, for example, by a method of ring-opening addition polymerization of an alkylene oxide having 2 to 4 carbon atoms (e.g., ethylene oxide, propylene oxide) with an initiator such as water or a hydroxyl group-containing compound in the presence of a catalyst such as an alkali hydroxide. Furthermore, the oxyalkylene units in the polyalkylene chain may be the same or may contain two or more types of oxyalkylene units in one molecule. It is preferred that at least an oxypropylene unit is contained in one molecule.

[0075] Examples of initiators 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.

[0076] The polyoxyalkylene oil is preferably, for example, an alkyl ether or ester of a polyoxyalkylene monool or a polyoxyalkylene polyol. Furthermore, the polyoxyalkylene oil is preferably a polyalkylene glycol oil. In particular, an alkyl ether of a polyalkylene glycol, called polyglycol oil, in which the terminal hydroxyl groups of the polyalkylene glycol are capped with an alkyl group such as a methyl group, is preferred.

[0077] Examples of fluorine-based refrigerating machine oils include compounds in which hydrogen atoms of synthetic oils (such as mineral oils, poly-α-olefins, alkylbenzenes, and alkylnaphthalenes described below) are substituted with fluorine atoms, fluorine-containing oils, perfluoropolyether oils, and fluorinated silicone oils.

[0078] Examples of mineral-based refrigerating machine oils include mineral oils (e.g., paraffinic mineral oils and naphthenic mineral oils) obtained by refining refrigerating machine oil fractions obtained by atmospheric or reduced pressure distillation of crude oil through an appropriate combination of refining treatments (solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, clay treatment, etc.).

[0079] Examples of hydrocarbon synthetic oils include poly-α-olefins, alkylbenzenes, and alkylnaphthalenes.

[0080] The refrigerating machine oil contained in the composition for a heat cycle system may be used alone or in combination of two or more kinds.

[0081] In particular, the refrigeration oil preferably contains at least one selected from the group consisting of polyalkylene glycol oil (PAG), polyol ester oil (POE), polyvinyl ether oil (PVE), silicone oil, fluorinated oil, mineral oil, and hydrocarbon synthetic oil, and more preferably contains at least one selected from the group consisting of polyalkylene glycol oil (PAG), polyol ester oil (POE), and polyvinyl ether oil (PVE).

[0082] The refrigerating machine oil may further contain an antioxidant, an extreme pressure agent, an acid scavenger, an oxygen scavenger, a copper deactivator, a rust inhibitor, an oiliness agent, an antifoaming agent, and the like.

[0083] The content of the refrigerating machine oil in the composition for a heat cycle system may be within a range that does not significantly reduce the effects of the present disclosure, and is preferably 10 parts by mass or more and 100 parts by mass or less, and more preferably 20 parts by mass or more and 50 parts by mass or less, relative to 100 parts by mass of the working fluid.

[0084] (Additives) The composition for a heat cycle system may contain, in addition to the working fluid and refrigerating machine oil, known additives such as tracers, stabilizers, polymerization inhibitors, and leak detection substances.

[0085] The tracer is preferably added at a detectable concentration so that any dilution, contamination, or other alteration in the working medium of the present disclosure can be tracked.

[0086] The composition for a heat cycle system may contain only one type of tracer, or two or more types of tracers.

[0087] The tracer is not particularly limited and can be appropriately selected from commonly used tracers. It is preferable to select a compound as the tracer that will not become an impurity that is inevitably mixed into the working fluid of the present disclosure.

[0088] Examples of tracers include hydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons, hydrochlorocarbons, fluorocarbons, deuterated hydrocarbons, deuterated hydrofluorocarbons, perfluorocarbons, fluoroethers, brominated compounds, iodinated compounds, alcohols, aldehydes, ketones, nitrous oxide (N ２ Among these, the tracer is preferably at least one selected from the group consisting of hydrofluorocarbons, hydrochlorofluorocarbons, chlorofluorocarbons, hydrochlorocarbons, fluorocarbons, and fluoroethers.

[0089] Preferred tracers 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, CHClF ２ ) HCFC-31 (chlorofluoromethane, CH ２ 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 OC HFCF ３ ) HFE-236fa (trifluoromethyl-trifluoroethyl ether, CF ３ OCH ２ CF ３ )

[0090] The content of the tracer is preferably from 10 to 1000 ppm by mass, more preferably from 30 to 500 ppm by mass, still more preferably from 50 to 300 ppm by mass, particularly preferably from 75 to 250 ppm by mass, and most preferably from 100 to 200 ppm by mass, based on the total amount of the working fluid.

[0091] The stabilizer is a component that improves the stability of the working fluid against heat and oxidation. Examples of the stabilizer include conventionally known stabilizers, such as oxidation resistance improvers, heat resistance improvers, and metal deactivators.

[0092] Examples of oxidation resistance improvers and heat resistance improvers include N,N'-diphenylphenylenediamine, 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-alkylphenothiazine, 6-(t-butyl)phenol, 2,6-di-(t-butyl)phenol, 4-methyl-2,6-di-(t-butyl)phenol, and 4,4'-methylenebis(2,6-di-t-butylphenol). One type of oxidation resistance improver and one type of heat resistance improver may be used alone, or two or more types may be used in combination.

[0093] Examples of metal deactivators include imidazole, benzimidazole, 2-mercaptobenzthiazole, 2,5-dimethylcaptothiadiazole, salicylidyne-propylenediamine, pyrazole, benzotriazole, tolutriazole, 2-methylbenzamidazole, 3,5-dimethylpyrazole, methylenebis-benzotriazole, organic acids or esters thereof, primary, secondary or tertiary aliphatic amines, amine salts of organic or inorganic acids, heterocyclic nitrogen-containing compounds, amine salts of alkyl acid phosphates or derivatives thereof, and the like.

[0094] The content of the stabilizer may be within a range that does not significantly reduce the effects of the present disclosure, and is typically 0.01 to 5 mass%, preferably 0.05 to 3 mass%, more preferably 0.1 to 2 mass%, even more preferably 0.25 to 1.5 mass%, and particularly preferably 0.5 to 1 mass%, relative to 100 parts by mass of the working fluid.

[0095] The polymerization inhibitor is not particularly limited and can be appropriately selected from commonly used polymerization inhibitors. The polymerization inhibitor contained in the composition for a heat cycle system may be one type or two or more types.

[0096] Examples of the polymerization inhibitor include 4-methoxy-1-naphthol, hydroquinone, hydroquinone methyl ether, dimethyl-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, and benzotriazole.

[0097] The content of the polymerization inhibitor is not particularly limited and is usually 0.01 to 5 mass%, preferably 0.05 to 3 mass%, more preferably 0.1 to 2 mass%, still more preferably 0.25 to 1.5 mass%, and particularly preferably 0.5 to 1 mass%, based on the total amount of the working fluid.

[0098] Leak detection materials include ultraviolet fluorescent dyes, odorous gases, and odor masking agents.

[0099] Examples of ultraviolet fluorescent dyes include conventionally known ultraviolet fluorescent dyes such as those described in U.S. Pat. No. 4,249,412, JP-A-10-502737, JP-A-2007-511645, JP-A-2008-500437, and JP-A-2008-531836.

[0100] Examples of odor masking agents include conventionally known fragrances such as those described in JP-A Nos. 2008-500437 and 2008-531836.

[0101] When a leak detection material is used, a solubilizing agent may be used to improve the solubility of the leak detection material in the working medium.

[0102] Examples of the solubilizing agent include those described in JP-T-2007-511645, JP-T-2008-500437, and JP-T-2008-531836.

[0103] The content of the leak detection substance may be within a range that does not significantly reduce the effects of the present disclosure, and is preferably 2 parts by mass or less, and more preferably 0.5 parts by mass or less, per 100 parts by mass of the working fluid.

[0104] The composition for a heat cycle system is used in a heat cycle system. The heat cycle system may be a heat pump system that uses hot heat obtained in a condenser, or may be a refrigeration cycle system that uses cold heat obtained in an evaporator.

[0105] [Heat cycle system] The heat cycle system of the present disclosure includes the working fluid or the composition for a heat cycle system of the present disclosure, a compressor that compresses vapor of the working fluid, a condenser that cools and liquefies the vapor of the working fluid discharged from the compressor, a pressure reducing device that reduces the pressure of the working fluid discharged from the condenser, and an evaporator that heats the working fluid discharged from the pressure reducing device, and the evaporator controls the evaporation temperature of the working fluid to −40° C. or higher.

[0106] The heat cycle system to which the working fluid is applied may be a heat pump device that uses hot heat obtained in a condenser, or may be a refrigeration cycle device that uses cold heat obtained in an evaporator. The heat cycle system of the present disclosure may be a direct expansion type or an indirect expansion type. Examples of indirect expansion types include a flooded evaporator type.

[0107] The thermal cycle includes a series of cycles in which the working medium is (1) compressed in a gaseous state by a compressor, (2) cooled in a condenser to change into a high-pressure liquid state, (3) the pressure is reduced by an expansion valve, which is an example of a pressure reducing device, and (4) vaporized at a low temperature in an evaporator to remove heat by the heat of vaporization. Compressors can be classified into turbo (centrifugal), reciprocating, rotary, twin-screw, single-screw, scroll compressors, etc. depending on the method of compressing the gaseous working medium, and can be selected based on heat capacity, compression ratio, and size.

[0108] (Refrigeration Cycle System) As an example of a heat cycle system, a refrigeration cycle system will be described. The refrigeration cycle system is a system in which a working medium removes thermal energy from a load fluid in an evaporator, thereby cooling the load fluid to a lower temperature.

[0109] 1 is a schematic diagram showing an example of a refrigeration cycle system according to the present disclosure. The refrigeration cycle system 10 generally includes a compressor 11 that compresses working fluid vapor A to produce high-temperature, high-pressure working fluid vapor B, a condenser 12 that cools and liquefies the working fluid vapor B discharged from the compressor 11 to produce low-temperature, high-pressure working fluid C, an expansion valve 13 that expands the working fluid C discharged from the condenser 12 to produce low-temperature, low-pressure working fluid D, an evaporator 14 that heats the working fluid D discharged from the expansion valve 13 to produce high-temperature, low-pressure working fluid vapor A, a pump 15 that supplies a load fluid E to the evaporator 14, and a pump 16 that supplies a fluid F to the condenser 12.

[0110] In the refrigeration cycle system 10, the following cycles (i) to (iv) are repeated: (i) Working fluid vapor A discharged from the evaporator 14 is compressed by the compressor 11 to produce high-temperature, high-pressure working fluid vapor B (hereinafter referred to as the "AB process"); (ii) Working fluid vapor B discharged from the compressor 11 is cooled by fluid F in the condenser 12 and liquefied to produce low-temperature, high-pressure working fluid C. During this process, fluid F is heated to produce fluid F', which is discharged from the condenser 12 (hereinafter referred to as the "BC process"); (iii) Working fluid C discharged from the condenser 12 is expanded by the expansion valve 13 to produce low-temperature, low-pressure working fluid D (hereinafter referred to as the "CD process"); (iv) Working fluid D discharged from the expansion valve 13 is heated by load fluid E in the evaporator 14 to produce high-temperature, low-pressure working fluid vapor A. During this process, load fluid E is cooled to produce load fluid E', which is discharged from the evaporator 14 (hereinafter referred to as the "DA process").

[0111] The refrigeration cycle system 10 is a cycle system consisting of an adiabatic isentropic change, an isenthalpic change, and an isobaric change. When the state change of the working medium is plotted on the pressure-enthalpy curve (curve) shown in Figure 2, A, B, C, and D can be represented as vertices.

[0112] The AB process is a process in which adiabatic compression is performed in the compressor 11 to convert low-temperature, low-pressure working fluid vapor A into high-temperature, high-pressure working fluid vapor B, and is shown by line AB in Figure 2. As described below, the working fluid vapor A is introduced into the compressor 11 in a superheated state, and the resulting working fluid vapor B is also superheated vapor. The compressor suction gas density is the density (ρs) at state A in Figure 2. The compressor discharge gas temperature (discharge temperature) is the temperature (Tx) at state B in Figure 2, which is the maximum temperature in the refrigeration cycle. The compressor discharge pressure (discharge pressure) is the pressure (Px) at state B in Figure 2, which is the maximum pressure in the refrigeration cycle. Note that since the BC process is isobaric cooling, the discharge pressure has the same value as the condensation pressure (Pc). Therefore, for convenience, the condensation pressure is shown as Px in Figure 2.

[0113] The BC process is a process in which isobaric cooling is performed in the condenser 12 to convert high-temperature, high-pressure working fluid vapor B into low-temperature, high-pressure working fluid C, and is shown by line BC in FIG. 2. The pressure at this time is the condensation pressure. Of the intersections of the pressure-enthalpy line and line BC, point T1 on the high-enthalpy side is the condensation temperature, and point T2 on the low-enthalpy side is the condensing boiling point temperature. Here, the temperature glide in the condenser when the working fluid is a non-azeotropic mixture is shown as the difference between T1 and T2.

[0114] In the BC process, the condensation temperature is preferably 75°C or lower, more preferably 70°C or lower, even more preferably 60°C or lower, and particularly preferably 55°C or lower. This is because the condensation temperature is preferably below the critical temperature of the working fluid. The critical temperature is the temperature at the end of the saturated liquid line and saturated vapor line on the high-pressure / high-temperature side. Above the critical temperature, neither evaporation nor liquefaction occurs, the liquid phase and the gas phase become indistinguishable, and no phase change occurs. If the temperature of the working fluid is below the critical temperature, the working fluid can be liquefied (condensed), and refrigeration performance can be maintained.

[0115] In the present disclosure, the critical temperature of the working fluid is preferably 70°C or higher, more preferably 75°C or higher.

[0116] The CD process is a process in which isenthalpic expansion is performed in the expansion valve 13 to convert the low-temperature, high-pressure working medium C into a low-temperature, low-pressure working medium D, and is shown by the line CD in Figure 2. If the temperature of the low-temperature, high-pressure working medium C is represented by T3, T2-T3 is the degree of supercooling (SC) of the working medium in the cycles (i) to (iv).

[0117] The DA process is a process in which isobaric heating is performed in the evaporator 14 to return the low-temperature, low-pressure working medium D to high-temperature, low-pressure working medium vapor A, and is shown by line DA in Figure 2. The pressure at this time is the evaporation pressure. Of the intersections of the pressure-enthalpy line and the DA line, point T6 on the high-enthalpy side is the evaporation temperature. Here, the temperature glide in the evaporator when the working medium is a non-azeotropic mixture is shown as the difference between T6 and T4. If the temperature of working medium vapor A is shown as T7, then T7 - ​​T6 is the degree of superheat (SH) of the working medium in cycles (i) to (iv). Note that T4 indicates the temperature of the working medium D.

[0118] The CAP and COP of the working fluid can be calculated from the following equations (11), (12), (13), and (14) using the enthalpies hA, hB, hC, and hD of the working fluid in each of the states A (after evaporation, low temperature and low pressure), B (after compression, high temperature and high pressure), C (after condensation, low temperature and high pressure), and D (after expansion, low temperature and low pressure), and the mass circulation rate qmr of the working fluid, respectively. It is assumed that there is no pressure loss in the piping and heat exchangers.

[0119] When the compressor's loss work is added to the working medium as heat, the working medium vapor B' after the A and B steps is expressed by the following formula using hA, hB, and η, using the compressor efficiency η: hB' = hA + (hB - hA) / η

[0120] The cycle performance of the working fluid is determined by performing theoretical calculations of the refrigeration cycle of the working fluid under the temperature conditions of a specified refrigeration cycle using the National Institute of Science and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10.0). The physical property data and mixing rule of HFO-1123 are calculated using the values ​​and measured values ​​described in Akasaka, R., Higashi, Y., Sakoda, N., Fukuda, S., and Lemmon, EW, 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, EW, 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 = wr × 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) Taking compressor efficiency into consideration, COP and P are expressed by the following formulas: COP = Q / P = (hA - hD) / (hB' - hA) (15) P = qmr(hB' - hA) (16)

[0121] The evaporator controls the evaporation temperature of the working medium to -40°C or higher, preferably -35°C or higher, and more preferably -30°C or higher.

[0122] The evaporator preferably controls the evaporation temperature of the working medium to −40 to 15° C., more preferably −35 to 15° C., and even more preferably −30 to 15° C. The evaporation temperature of the working medium in the evaporator may be automatically controlled.

[0123] In this disclosure, the evaporation temperature refers to the temperature at which a working fluid absorbs heat and becomes vapor during the evaporation process of a heat cycle system. In this disclosure, the condensation temperature refers to the temperature at which a working fluid vapor releases heat and becomes liquid during the condensation process of a heat cycle system. The evaporation temperature can be determined by measuring the temperature at the evaporator inlet and / or outlet. For single media and azeotropic media mixtures, the evaporation temperature is constant. However, for non-azeotropic media mixtures, the evaporation temperature is the average temperature between the evaporation start temperature and the evaporation completion temperature. Therefore, the evaporation temperature is calculated as "evaporation temperature = (evaporation start temperature + evaporation completion temperature) / 2." The condensation temperature can be determined by measuring the temperature at the condenser inlet and / or outlet. For single media and azeotropic media mixtures, the condensation temperature is constant. However, for non-azeotropic media mixtures, the condensation temperature is the average temperature between the condensation start temperature and the condensation completion temperature. Therefore, the condensation temperature is calculated as "condensation temperature = (condensation start temperature + condensation completion temperature) / 2."

[0124] Specific examples of thermal cycle systems include refrigeration and freezing equipment, air conditioning equipment, heating and hot water supply equipment, power generation systems, heat transport devices, and secondary cooling machines. Among these, thermal cycle systems are preferably used as air conditioning equipment, which is often installed outdoors, because they can stably and safely demonstrate thermal cycle performance even in higher temperature operating environments. Thermal cycle systems are also preferably used as refrigeration and freezing equipment.

[0125] Specific examples of air conditioning equipment include room air conditioners, packaged air conditioners (packaged air conditioners for stores, packaged air conditioners for buildings, packaged air conditioners for facilities, etc.), gas engine heat pumps, train air conditioners, automotive air conditioners, etc. The automotive air conditioners are preferably air conditioners for gasoline vehicles, air conditioners for hybrid vehicles, air conditioners for electric vehicles, or air conditioners for hydrogen vehicles, and more preferably air conditioners for electric vehicles.

[0126] Specific examples of refrigeration and freezing equipment include showcases (refrigerated showcases, freezer showcases, etc.), refrigerators, freezers, water chillers, freezing and refrigeration units, freezers for refrigerated and frozen warehouses, chillers (chilling units), turbo freezers, screw freezers, vending machines, and ice makers.

[0127] Specific examples of the heating and hot water equipment include heat pump water heaters, heat pump hot water heaters, heat pump hot air heaters, steam hot air generating heat pumps, and exhaust heat recovery heat pumps.

[0128] The power generation system is preferably a Rankine cycle power generation system, specifically, a system in which a working medium is heated in an evaporator by geothermal energy, solar heat, or waste heat in a medium to high temperature range of about 50°C to 200°C, and the working medium is adiabatically expanded in an expander to become high-temperature, high-pressure vapor, and the work generated by the adiabatic expansion drives a generator to generate electricity.

[0129] The heat transport device is preferably a latent heat transport device. Examples of latent heat transport devices include heat pipes and two-phase closed thermosiphon devices, which transport latent heat by utilizing phenomena such as evaporation, boiling, and condensation of a working medium sealed within the device. Heat pipes are used in relatively small cooling devices, such as cooling devices for heat-generating parts of semiconductor elements and electronic devices. Two-phase closed thermosiphon devices do not require a wig and have a simple structure, so they are widely used in gas-gas heat exchangers, for promoting snow melting and preventing freezing on roads, etc.

[0130] [Thermal Cycle Method] The thermal cycle method of the present disclosure is a method of compressing the vapor of the working fluid of the present disclosure, cooling and liquefying the vapor of the working fluid discharged from the compressor, depressurizing the liquefied working fluid, and heating the depressurized working fluid at an evaporation temperature of −40° C. or higher. The evaporation temperature is preferably −35° C. or higher, more preferably −30° C. or higher. Details of the working fluid and the thermal cycle are as described above.

[0131] In the heat cycle method of the present disclosure, the reduced pressure working fluid is preferably heated at an evaporation temperature of -40 to 15°C, more preferably at an evaporation temperature of -35 to 15°C, and even more preferably at an evaporation temperature of -30 to 15°C.

[0132] The present disclosure will be described in more detail below with reference to examples, but the embodiments of the present disclosure are not limited to the following examples. Examples 1 to 4 are reference examples, Examples 5 to 9 are comparative examples, and Examples 10 to 45 are working examples.

[0133] Working fluids containing HFO-1123, HFO-1234yf, and carbon dioxide, whose compositions (mass%) are shown in Tables 2 and 3, were evaluated. In the tables, "-" means that the corresponding component was not contained. For the working fluids, the saturated vapor pressures at -40°C, -35°C, and -30°C, the saturated liquid pressure at 55°C, GWP, and combustion heat quantity were calculated. The saturated vapor pressure and saturated liquid pressure were also calculated as relative values ​​when the saturated vapor pressure and saturated liquid pressure of R404A were set to 1.000, respectively. The calculation method was as described above.

[0134] When the working medium is a single medium or an azeotropic mixture, the saturated liquid pressure and saturated vapor pressure at the same temperature are substantially the same. On the other hand, when the working medium is a non-azeotropic mixture, the saturated liquid pressure and saturated vapor pressure at the same temperature are different values. The evaporation pressure is calculated as "evaporation temperature = (evaporation start temperature + evaporation end temperature) / 2," where the evaporation temperature is the average temperature of the evaporation start temperature and the evaporation end temperature. Therefore, the minimum evaporation pressure in a heat cycle system can be determined from the saturated vapor pressure at the temperature set and controlled as the evaporation temperature. The condensation pressure is calculated as "condensation temperature = (condensation start temperature + condensation end temperature) / 2," where the condensation temperature is the average temperature of the condensation start temperature and the condensation end temperature. Therefore, the maximum condensation pressure in a heat cycle system can be determined from the saturated liquid pressure at the temperature set and controlled as the condensing temperature.

[0135] In Tables 2 and 3, the value shown in "the left side value of formula (A1)" is a value calculated from "-2.20X + 25.60" when the carbon dioxide content is X% by mass. The value shown in "the right side value of formula (A1)" is a value calculated from "-5.58X + 61.74" when the carbon dioxide content is X% by mass. The value shown in "the right side value of formula (A3)" is a value calculated from "-5.67X + 56.20" when the carbon dioxide content is X% by mass. When the content of HFO-1123 is Y% by mass, if Y is equal to or greater than "the left side value of formula (A1)", "Y" is entered in the "left side value of formula (A1)" column, and if Y is less than "the left side value of formula (A1)", "N" is entered. When the content of HFO-1123 is Y mass%, if Y is equal to or less than the "right side value of formula (A1)", "Y" is entered in the column for "right side value of formula (A1)", and if Y exceeds the "right side value of formula (A1)", "N" is entered. When the content of HFO-1123 is Y mass%, if Y is equal to or less than the "right side value of formula (A3)", "Y" is entered in the column for "right side value of formula (A3)", and if Y exceeds the "right side value of formula (A3)", "N" is entered.

[0136]

[0137]

[0138] As shown in Tables 2 and 3, in Examples 10 to 45, the working fluid contained HFO-1123, HFO-1234yf, and carbon dioxide, and when the content of carbon dioxide relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide was X% by mass, and the content of HFO-1123 relative to the total content of HFO-1123, HFO-1234yf, and carbon dioxide was Y% by mass, X and Y satisfied the formulas (A1) and (A2), and the total content of HFO-1123, HFO-1234yf, and carbon dioxide was 99.0% by mass or more based on the total amount of the working fluid, the saturated vapor pressure at -40°C was 0.082 MPa or more, the saturated vapor pressure at -35°C was 0.104 MPa or more, and the saturated vapor pressure at -30°C was 0.130 MPa or more. Furthermore, the saturated liquid pressure at 55°C was 3.150 MPa or less. Therefore, it is considered that the working fluids of Examples 10 to 45 can be suitably used as substitutes for R404A. Furthermore, the saturated liquid pressure at 55°C of the working fluids of Examples 10 to 45 is equal to or less than the saturated liquid pressure of R410A at 55°C. Therefore, it is considered that the working fluids of Examples 10 to 45 can be suitably used as substitutes for R410A.

[0139] In particular, in Examples 10 to 27, 29 to 30, 32, 34, and 36 to 40, X and Y satisfied the formulas (A1), (A2), and (A3), respectively, and therefore the saturated vapor pressure at 55° C. was 3.000 MPa or less.

[0140] In addition, in Examples 10 to 45, the working fluid contains an appropriate amount of carbon dioxide, so the amount of heat of combustion is kept to 10.310 MJ / kg or less.

[0141] On the other hand, in Examples 6 and 7, the working fluid had an HFO-1123 content less than the value of the left side of formula (A1), and therefore the saturated vapor pressure at −40° C. was less than 0.082 MPa, the saturated vapor pressure at −35° C. was less than 0.104 MPa, and the saturated vapor pressure at −30° C. was less than 0.130 MPa.

[0142] In Examples 5, 8 and 9, the content of HFO-1123 was greater than the value of the right-hand side of formula (A1), and therefore the saturated vapor pressure at 55°C exceeded 3.150 MPa.

[0143] For the working fluids of Examples 1, 5 to 10, 12, 14 to 36, 38, 40, 42, 43, and 45 (Conditions 1 and 2), or Examples 1, 2, 5 to 10, 12, 14 to 36, 38, 40, 42, 43, and 45 (Conditions 3 and 4), the refrigeration cycle state was calculated based on the theoretical refrigeration cycle performance calculation, with the condensation temperature, evaporation temperature, degree of superheat (SH), degree of subcooling (SC), and compressor efficiency set as follows. The discharge temperature (referred to as "Td" in the table), condensation pressure (referred to as "Pc" in the table), evaporation pressure (referred to as "Pe" in the table), refrigeration effect (referred to as "Wr" in the table), coefficient of performance (referred to as "COP" in the table), and capacity per unit volume (referred to as "CAP" in the table) were calculated. The measurement methods for Td, Pc, Pe, Wr, COP, and CAP are as described above. The results are shown in Tables 4 to 7. In Tables 4 to 7, Pc, Pe, Wr, COP, and CAP were evaluated by converting them into relative values ​​with the value of R404A as the standard (R404A=1.000).

[0144] (Conditions in Table 4: Condition 1) Condensation temperature: 40°C Evaporation temperature: -40°C Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0145] (Conditions in Table 5: Condition 2) Condensation temperature: 40°C Evaporation temperature: -20°C Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0146] (Conditions in Table 6: Condition 3) Condensation temperature: 40°C Evaporation temperature: 0°C Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0147] (Conditions in Table 7: Condition 4) Condensation temperature: 40°C Evaporation temperature: 15°C Superheat (SH): 20°C Subcooling (SC): 0°C Compressor efficiency: 0.7

[0148]

[0149]

[0150]

[0151]

[0152] From Tables 4 to 7, it can be seen that in the refrigeration cycles using the working fluids of Examples 10 to 45 that satisfy formulas (A1) and (A2), the COP tends to be 0.985 or more and the CAP tends to be 0.781 or more, relative to R404A. Furthermore, it can be seen that the working fluids of Examples 10 to 45 provide good COP and CAP, even compared to R410A. From the above, the heat cycle system of the present disclosure that uses these working fluids instead of R404A or R410A provides excellent cycle performance.

[0153] The disclosure of Japanese Patent Application No. 2023-100364, filed on June 19, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

[0154] REFRIGERATION CYCLE SYSTEM 10 11 Compressor 12 Condenser 13 Expansion valve 14 Evaporator 15, 16 Pump

Claims

1. A working fluid containing trifluoroethylene, 2,3,3,3-tetrafluoropropene, and carbon dioxide, wherein, when the content of the carbon dioxide relative to the total content of the trifluoroethylene, the 2,3,3,3-tetrafluoropropene, and the carbon dioxide is X mass % and the content of the trifluoroethylene relative to the total content of the trifluoroethylene, the 2,3,3,3-tetrafluoropropene, and the carbon dioxide is Y mass %, X and Y satisfy the following formulas (A1) and (A2), and the total content of the trifluoroethylene, the 2,3,3,3-tetrafluoropropene, and the carbon dioxide is 99.0 mass % or more relative to the total amount of the working fluid. -2.20X+25.60≦Y≦-5.58X+61.74 ... (A1) 2.5≦X≦6.0 ... (A2) 2. The working fluid according to claim 1, wherein X and Y further satisfy the following formula (A3): -2.20X + 25.60 ≦ Y ≦ -5.67X + 56.20 ... (A3).

3. The working medium according to claim 1, wherein X is 3.0 to 4.

0.

4. The working medium according to claim 1, wherein Y is 25.0 to 40.

0.

5. The working medium according to claim 1, having a combustion heat of 10.310 MJ / kg or less.

6. A composition for a heat cycle system, comprising the working fluid according to any one of claims 1 to 5 and a refrigeration oil.

7. The composition for a heat cycle system according to claim 6, wherein the refrigeration oil comprises at least one selected from the group consisting of polyalkylene glycol oil (PAG), polyol ester oil (POE), and polyvinyl ether oil (PVE).

8. A heat cycle system comprising: a working medium according to any one of claims 1 to 5; a compressor that compresses the vapor of the working medium; a condenser that cools and liquefies the vapor of the working medium discharged from the compressor; a pressure reducing device that reduces the pressure of the working medium discharged from the condenser; and an evaporator that heats the working medium discharged from the pressure reducing device, wherein the evaporator controls the evaporation temperature of the working medium to be -40°C or higher.

9. The heat cycle system according to claim 8, wherein the evaporator controls the evaporation temperature of the working medium to -35°C or higher.

10. The heat cycle system according to claim 8, wherein the evaporator controls the evaporation temperature of the working medium to -30°C or higher.

11. A heat cycle method comprising compressing vapor of the working medium according to any one of claims 1 to 5, cooling and liquefying the vapor of the working medium, depressurizing the liquefied working medium, and heating the depressurized working medium at an evaporation temperature of -40°C or higher.

12. The heat cycle method according to claim 11, wherein the reduced pressure working medium is heated to an evaporation temperature of -35°C or higher.

13. The heat cycle method according to claim 11, wherein the reduced pressure working medium is heated to an evaporation temperature of -30°C or higher.