Working medium and heat cycle system

Abstract

To provide: a working medium for heat cycle, which has suppressed flammability, little effect on the ozone layer, and little effect on global warming and provides a heat cycle system having excellent cyclic performance (capacity); and a heat cycle system which secures safety and has excellent cycle performance (capacity).SOLUTION: Provided is a working medium for heat cycle, comprising 1,1,2-trifluoroethylene and hydrofluorocarbon (except, however, one comprising difluoromethane), where a content of working medium, contained in the working medium for heat cycle, other than 1,1,2-trifluoroethylene and hydrofluorocarbon, is 30 mass% or less in a working medium-containing composition (100 mass%) comprising the working medium for heat cycle. The working medium for heat cycle is used for a heat cycle system (Rankine cycle system, heat pump cycle system, refrigeration cycle system 10, heat transport system, and the like).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a working fluid and a heat cycle system using the working fluid for a heat cycle. [Background technology]

[0002] Traditionally, chlorofluorocarbons (CFCs) such as chlorotrifluoromethane and dichlorodifluoromethane, or hydrochlorofluorocarbons (HCFCs) such as chlorodifluoromethane, have been used as refrigerants for refrigerators, refrigerants for air conditioners, 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 media. However, CFCs and HCFCs are currently subject to regulation due to their potential impact on the stratospheric ozone layer.

[0003] Therefore, hydrofluorocarbons (HFCs) such as difluoromethane (HFC-32), tetrafluoroethane, and pentafluoroethane, which have little impact on the ozone layer, are used as working fluids for heat cycles. However, it has been pointed out that HFCs may cause global warming. Therefore, there is an urgent need to develop working fluids for heat cycles that have little impact on the ozone layer and a small global warming potential.

[0004] For example, 1,1,1,2-tetrafluoroethane (HFC-134a), which is used as a refrigerant in automotive air conditioners, has a high global warming potential of 1430 (100-year value). Moreover, in automotive air conditioners, there is a high probability that the refrigerant will leak into the atmosphere from connecting hoses, bearings, etc.

[0005] As refrigerants to replace HFC-134a, carbon dioxide and 1,1-difluoroethane (HFC-152a), which has a lower global warming potential of 124 (100-year value) than HFC-134a, are being considered. However, carbon dioxide has a much higher equipment pressure than HFC-134a, and there are many issues to be resolved before it can be used in all automobiles.HFC-152a has a flammable range, and there are issues to be resolved in order to ensure safety.

[0006] Hydrofluoroolefins (HFOs), which have carbon-carbon double bonds that are easily decomposed by OH radicals in the atmosphere, are considered to be working fluids for heat cycles that have little impact on the ozone layer and little impact on global warming. For example, the following are known working fluids for the heat cycle of HFO: (1) 3,3,3-trifluoropropene (HFO-1243zf), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 2-fluoropropene (HFO-1261yf), 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,1,2-trifluoropropene (HFO-1243yc) (Patent Document 1). (2) 1,2,3,3,3-pentafluoropropene (HFO-1225ye), trans-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), cis-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), and HFO-1234yf (Patent Document 2).

[0007] However, all of the HFOs in (1) have insufficient cycle performance (capacity). In addition, HFOs in (1) that have a low proportion of fluorine atoms are flammable. (2) HFO also has insufficient cycle performance (capacity). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 04-110388 [Patent Document 2] Japan Special Publication No. 2006-512426 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention provides a working fluid for a heat cycle that has reduced flammability, has little impact on the ozone layer, has little impact on global warming, and provides a heat cycle system with excellent cycle performance (capacity), and also provides a heat cycle system that ensures safety and has excellent cycle performance (capacity). [Means for solving the problem]

[0010] The present invention is characterized in that the working fluid for heat cycle (hereinafter also referred to as working fluid) contains 1,1,2-trifluoroethylene (hereinafter also referred to as HFO-1123) and an HFC (excluding those containing difluoromethane). In the present invention, the content of the other working fluid other than HFO-1123 and the HFC contained in the working fluid is such that the content of the other working fluid is 30% by mass or less in the working fluid-containing composition (100% by mass) containing the working fluid. The working medium of the present invention preferably further contains a hydrocarbon. The working fluid of the present invention preferably further contains a hydrochlorofluoroolefin (HCFO) or a chlorofluoroolefin (CFO). The heat cycle system of the present invention is characterized by using the working fluid of the present invention. [Effects of the Invention]

[0011] The working fluid of the present invention contains HFO-1123, which has a carbon-carbon double bond that is easily decomposed by OH radicals in the atmosphere, and therefore has little impact on the ozone layer and little impact on global warming. Furthermore, the inclusion of HFO-1123 provides a heat cycle system with excellent cycle performance (capacity). The thermal cycle system of the present invention uses the working fluid of the present invention, which has excellent thermodynamic properties, and therefore has excellent cycle performance (capacity). Furthermore, the excellent capacity allows the system to be made smaller. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating an example of a refrigeration cycle system. [Figure 2] This is a cycle diagram showing the state change of the working medium in a refrigeration cycle system on a temperature-entropy diagram. [Figure 3] This is a cycle diagram in which the state change of the working medium in a refrigeration cycle system is plotted on a pressure-enthalpy diagram. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Working medium> The working fluid of the present invention contains 1,1,2-trifluoroethylene. The working fluid of the present invention may, if necessary, contain other working fluids that vaporize or liquefy together with HFO-1123, such as hydrocarbons, HFCs, HCFOs, and CFOs. The working fluid of the present invention can also be used in combination with components other than the working fluid (hereinafter, a composition containing a working fluid and a component other than the working fluid is referred to as a working fluid-containing composition). Examples of components other than the working fluid include lubricating oils, stabilizers, leak detection materials, desiccants, and other additives. The content of HFO-1123 in the working fluid (100% by mass) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 100% by mass.

[0014] (hydrocarbons) The hydrocarbon is a component of the working medium that improves the solubility of the working medium in the mineral lubricating oil. The hydrocarbon preferably has 3 to 5 carbon atoms and may be linear or branched. Specific examples of the hydrocarbon include propane, propylene, cyclopropane, butane, isobutane, pentane, and isopentane. The hydrocarbons may be used alone or in combination of two or more.

[0015] The content of hydrocarbons in the working fluid (100% by mass) is preferably 1 to 40% by mass, more preferably 2 to 10% by mass. If the content of hydrocarbons is 1% by mass or more, the solubility of the lubricating oil in the working fluid is sufficiently improved. If the content of hydrocarbons is 40% by mass or less, it is effective in suppressing the flammability of the working fluid.

[0016] (HFC) HFCs are working fluid components that improve the cycle performance (capacity) of heat cycle systems. As the HFC, an HFC that has little impact on the ozone layer and has little impact on global warming is preferable.

[0017] The HFC preferably has 1 to 5 carbon atoms and may be linear or branched. Specific examples of HFCs include difluoromethane, difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, pentafluorobutane, heptafluorocyclopentane, etc. Among these, difluoromethane (HFC-32), 1,1-difluoroethane (HFC-152a), 1,1,2,2-tetrafluoroethane (HFC-134), 1,1,1,2-tetrafluoroethane (HFC-134a), and pentafluoroethane (HFC-125) are particularly preferred because of their small impact on the ozone layer and their small impact on global warming. The HFC may be used alone or in combination of two or more.

[0018] The content of HFC in the working fluid (100% by mass) is preferably 1 to 99% by mass, more preferably 1 to 60% by mass. For example, when the HFC is HFC-32, the coefficient of performance and refrigeration capacity are improved in the range of 1 to 99% by mass. When HFC-134a is used, the coefficient of performance is improved in the range of 1 to 99% by mass. When HFC-125 is used, the coefficient of performance and refrigeration capacity decrease, but the decrease is not significant. The HFC content can be controlled depending on the required properties of the working fluid.

[0019] (HCFO, CFO) HCFOs and CFOs are working fluid components that reduce the flammability of the working fluid and also improve the solubility of lubricating oil in the working fluid. As HCFOs and CFOs, HCFOs that have little impact on the ozone layer and little impact on global warming are preferred.

[0020] The HCFO preferably has 2 to 5 carbon atoms and may be linear or branched. Specific examples of HCFOs include hydrochlorofluoropropene, hydrochlorofluoroethylene, etc. Among these, 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd) and 1-chloro-1,2-difluoroethylene (HCFO-1122) are particularly preferred in terms of sufficiently suppressing the flammability of the working fluid without significantly reducing the cycle performance (capacity) of the heat cycle system. The HCFO may be used alone or in combination of two or more.

[0021] CFO preferably has 2 to 5 carbon atoms and may be linear or branched. Specific examples of CFOs include chlorofluoropropene, chlorofluoroethylene, etc. Among them, 1,1-dichloro-2,3,3,3-tetrafluoropropene (CFO-1214ya) and 1,2-dichloro-1,2-difluoroethylene (CFO-1112) are particularly preferred in terms of sufficiently suppressing the flammability of the working fluid without significantly reducing the cycle performance (capacity) of the heat cycle system.

[0022] The total content of HCFO and CFO is preferably 1 to 60 mass% of the working fluid (100 mass%). Chlorine atoms have the effect of suppressing flammability, and the addition of HCFO and CFO can sufficiently suppress the flammability of the working fluid without significantly reducing the cycle performance (capacity) of the heat cycle system.

[0023] (lubricating oil) As the lubricating oil used in the working fluid-containing composition, a known lubricating oil used in a heat cycle system can be used. Examples of lubricating oils include oxygen-containing synthetic oils (ester-based lubricating oils, ether-based lubricating oils, etc.), fluorine-based lubricating oils, mineral oils, and hydrocarbon-based synthetic oils.

[0024] Examples of ester-based lubricating oils include dibasic acid ester oils, polyol ester oils, complex ester oils, and polyol carbonate ester oils.

[0025] Preferred dibasic acid ester oils are esters of dibasic acids having 5 to 10 carbon atoms (such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid) with monohydric alcohols having 1 to 15 carbon atoms and a linear or branched alkyl group (such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, and pentadecanol). Specific examples include ditridecyl glutarate, di(2-ethylhexyl) adipate, diisodecyl adipate, ditridecyl adipate, and di(3-ethylhexyl) sebacate.

[0026] 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 (linear or branched fatty acids such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, eicosanoic acid, oleic acid, etc., or so-called neo acids in which the α-carbon atom is quaternary). The polyol ester oil may have a free hydroxyl group. Preferred polyol ester oils are esters of hindered alcohols (neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, etc.) (trimethylolpropane tripelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol tetrapelargonate, etc.).

[0027] The complex ester oil is an ester of a fatty acid or dibasic acid with a monohydric alcohol or polyol. The fatty acid, dibasic acid, monohydric alcohol, and polyol may be the same as those described above.

[0028] The polyol carbonate oil is an ester of carbonic acid and a polyol. The polyol may be the same diol or polyol as described above. The polyol carbonate oil may be a ring-opening polymer of a cyclic alkylene carbonate.

[0029] Examples of ether-based lubricating oils include polyvinyl ether oils and polyoxyalkylene-based lubricating oils. Polyvinyl ether oils include those 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. The vinyl ether monomers may be used alone or in combination of two or more. 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. The polyvinyl ether copolymer may be either a block or random copolymer. The polyvinyl ether may be used alone or in combination of two or more kinds.

[0030] Examples of polyoxyalkylene lubricating oils include polyoxyalkylene monools, polyoxyalkylene polyols, alkyl ethers of polyoxyalkylene monools or polyoxyalkylene polyols, and esters of polyoxyalkylene monools or polyoxyalkylene polyols. Examples of polyoxyalkylene monools or polyoxyalkylene polyols include those obtained by ring-opening addition polymerization of an alkylene oxide having 2 to 4 carbon atoms (e.g., ethylene oxide, propylene oxide, etc.) 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. Examples of initiators include water, monohydric alcohols such as methanol and butanol, and polyhydric alcohols such as ethylene glycol, propylene glycol, pentaerythritol, and glycerol.

[0031] As the polyoxyalkylene lubricating oil, alkyl ethers or esters of polyoxyalkylene monools or polyoxyalkylene polyols are preferred. As the polyoxyalkylene polyol, polyoxyalkylene glycols are preferred. In particular, alkyl ethers of polyoxyalkylene glycols, called polyglycol oils, in which the terminal hydroxyl groups of polyoxyalkylene glycols are capped with alkyl groups such as methyl groups, are preferred.

[0032] Examples of fluorine-based lubricating oils include compounds in which hydrogen atoms of synthetic oils (such as mineral oils, polyα-olefins, alkylbenzenes, and alkylnaphthalenes described below) are substituted with fluorine atoms, perfluoropolyether oils, and fluorinated silicone oils.

[0033] Examples of mineral oils include paraffinic mineral oils and naphthenic mineral oils, which are obtained by refining lubricating oil fractions obtained by atmospheric or vacuum distillation of crude oil through an appropriate combination of refining processes (solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, clay treatment, etc.).

[0034] Examples of hydrocarbon synthetic oils include poly-α-olefins, alkylbenzenes, and alkylnaphthalenes.

[0035] The lubricating oil may be used alone or in combination of two or more. As the lubricating oil, polyol ester oil and / or polyglycol oil are preferred from the viewpoint of compatibility with the working fluid, and polyalkylene glycol oil is particularly preferred from the viewpoint of the remarkable antioxidant effect that can be obtained by the stabilizer.

[0036] The content of the lubricating oil may be within a range that does not significantly reduce the effects of the present invention, and varies depending on the application, type of compressor, etc., but is preferably 10 to 100 parts by mass, more preferably 20 to 50 parts by mass, relative to the working fluid (100 parts by mass).

[0037] (stabilizer) The stabilizer used in the working fluid-containing composition is a component that improves the stability of the working fluid against heat and oxidation. Examples of the stabilizer include an oxidation resistance improver, a heat resistance improver, and a metal deactivator.

[0038] 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, 4,4'-methylenebis(2,6-di-t-butylphenol), etc. 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.

[0039] Examples of metal deactivators include imidazole, benzimidazole, 2-mercaptobenzthiazole, 2,5-dimethylcaptothiadiazole, salicylidin-propylenediamine, pyrazole, benzotriazole, tolutriazole, 2-methylbenzamidazole, 3,5-imethylpyrazole, 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.

[0040] The content of the stabilizer may be within a range that does not significantly reduce the effects of the present invention, and is preferably 5% by mass or less, more preferably 1% by mass or less, of the working fluid-containing composition (100% by mass).

[0041] (Leak detection material) Leak detection materials used in working fluid-containing compositions include ultraviolet fluorescent dyes, odorous gas and odor masking agents, and the like. Examples of ultraviolet fluorescent dyes include 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. Examples of odor masking agents include known fragrances such as those described in JP-A-2008-500437 and JP-A-2008-531836.

[0042] 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. Examples of the solubilizing agent include those described in JP-T-2007-511645, JP-T-2008-500437, and JP-T-2008-531836.

[0043] The content of the leak detection substance may be within a range that does not significantly reduce the effects of the present invention, and is preferably 2 mass % or less, more preferably 0.5 mass % or less, in the working fluid-containing composition (100 mass %).

[0044] (other compounds) The working fluid and working fluid-containing composition of the present invention may contain an alcohol having 1 to 4 carbon atoms or a compound used as a conventional working fluid, refrigerant, or heat transfer medium (hereinafter, such alcohols and compounds will be collectively referred to as "other compounds").

[0045] Other compounds include the following compounds: Fluorinated ethers: perfluoropropyl methyl ether (C3F7OCH3), perfluorobutyl methyl ether (C4F9OCH3), perfluorobutyl ethyl ether (C4F9OC2H5), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (CF2HCF2OCH2CF3, manufactured by Asahi Glass Co., Ltd., AE-3000), etc.

[0046] The content of other compounds may be within a range that does not significantly reduce the effects of the present invention, and is preferably 30 mass% or less, more preferably 20 mass% or less, and particularly preferably 15 mass% or less, of the working fluid-containing composition (100 mass%).

[0047] <Thermal cycle system> The heat cycle system of the present invention is a system using the working fluid of the present invention. Examples of heat cycle systems include Rankine cycle systems, heat pump cycle systems, refrigeration cycle systems, and heat transport systems.

[0048] (Refrigeration cycle system) As an example of a heat cycle system, a refrigeration cycle system will be described. A 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.

[0049] 1 is a schematic diagram showing an example of a refrigeration cycle system of the present invention. The refrigeration cycle system 10 is generally configured to include 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.

[0050] In the refrigeration cycle system 10, the following cycle is repeated. (i) The working medium vapor A discharged from the evaporator 14 is compressed by the compressor 11 to produce high-temperature and high-pressure working medium vapor B. (ii) The working fluid vapor B discharged from the compressor 11 is cooled by the fluid F in the condenser 12 and liquefied to become a low-temperature, high-pressure working fluid C. At this time, the fluid F is heated to become a fluid F' and is discharged from the condenser 12. (iii) The working medium C discharged from the condenser 12 is expanded by the expansion valve 13 to produce a low-temperature, low-pressure working medium D. (iv) The working medium D discharged from the expansion valve 13 is heated by the load fluid E in the evaporator 14 to become a high-temperature, low-pressure working medium vapor A. At this time, the load fluid E is cooled to become a load fluid E' and is discharged from the evaporator 14.

[0051] The refrigeration cycle system 10 is a cycle consisting of adiabatic-isentropic changes, isenthalpic changes, and isobaric changes, and the state changes of the working medium can be expressed on a temperature-entropy diagram as shown in FIG. In Figure 2, process AB is a process in which adiabatic compression is performed in compressor 11 to convert high-temperature, low-pressure working medium vapor A into high-temperature, high-pressure working medium vapor B. Process BC is a process in which isobaric cooling is performed in condenser 12 to convert high-temperature, high-pressure working medium vapor B into low-temperature, high-pressure working medium C. Process CD is a process in which isenthalpic expansion is performed in expansion valve 13 to convert low-temperature, high-pressure working medium C into low-temperature, low-pressure working medium D. Process DA is a process in which isobaric heating is performed in evaporator 14 to return low-temperature, low-pressure working medium D to high-temperature, low-pressure working medium vapor A.

[0052] Similarly, the state change of the working medium can be plotted on a pressure-enthalpy diagram as shown in Figure 3.

[0053] (moisture concentration) Water contamination in thermal cycle systems is a problem. Water contamination can cause freezing in capillary tubes, hydrolysis of the working fluid and lubricating oil, material degradation due to acid components generated in the thermal cycle, and the generation of contaminants. In particular, the aforementioned ether-based lubricating oils and ester-based lubricating oils are highly hygroscopic and prone to hydrolysis. Water contamination reduces their lubricating properties and significantly reduces the long-term reliability of compressors. Furthermore, in automotive air conditioning systems, water tends to be easily introduced through refrigerant hoses used to absorb vibrations and compressor bearings. Therefore, to prevent hydrolysis of the lubricating oil, it is necessary to suppress the water concentration in the thermal cycle system. The water concentration of the working fluid in a thermal cycle system is preferably 100 ppm or less, more preferably 20 ppm or less.

[0054] One method for suppressing the moisture concentration in a heat cycle system is to use a desiccant (silica gel, activated alumina, zeolite, etc.). Zeolite-based desiccants are preferred as desiccants in terms of their chemical reactivity with the working fluid and their moisture absorption capacity.

[0055] When using a lubricating oil that has a higher moisture absorption capacity than conventional mineral lubricating oils, a zeolite-based desiccant containing as its main component a compound represented by the following formula (1) is preferred because of its excellent moisture absorption capacity. M 2 / n O·Al2O3·xSiO2·yH2O ···(1). where M is a Group 1 element such as Na or K or a Group 2 element such as Ca, n is the valence of M, and x and y are values ​​determined by the crystal structure. The pore size can be adjusted by changing M.

[0056] In selecting a desiccant, pore size and crushing strength are important. When a desiccant having a pore size larger than the molecular diameter of the working fluid is used, the working fluid is adsorbed into the desiccant, resulting in a chemical reaction between the working fluid and the desiccant, which can lead to undesirable phenomena such as the generation of non-condensable gases, a decrease in the strength of the desiccant, and a decrease in its adsorption capacity. Therefore, it is preferable to use a zeolite-based desiccant with a small pore size. In particular, sodium-potassium A-type synthetic zeolite with a pore size of 3.5 Å or less is preferred. By using sodium-potassium A-type synthetic zeolite with a pore size smaller than the molecular size of the working fluid, it is possible to selectively adsorb and remove only the moisture in the heat cycle system without adsorbing the working fluid. In other words, since the working fluid is less likely to be adsorbed onto the desiccant, thermal decomposition is less likely to occur, which in turn suppresses deterioration of the materials that make up the heat cycle system and the generation of contaminants.

[0057] The size of the zeolite desiccant is preferably about 0.5 to 5 mm, since if it is too small it can clog the valves and piping of the heat cycle system, while if it is too large it reduces the drying ability.The shape is preferably granular or cylindrical. Zeolite-based desiccants can be formed into any shape by solidifying powdered zeolite with a binder (such as bentonite). As long as the main component is zeolite-based desiccants, other desiccants (such as silica gel and activated alumina) may be used in combination. The ratio of the zeolite-based desiccant to the working fluid is not particularly limited.

[0058] (chlorine concentration) The presence of chlorine in a heat cycle system can have undesirable effects, such as deposit formation due to reactions with metals, wear of bearings, and decomposition of working fluids and lubricants. The chlorine concentration in the heat cycle system is preferably 100 ppm or less, particularly preferably 50 ppm or less, in terms of mass ratio to the working fluid.

[0059] (non-condensable gas concentration) If non-condensable gases are introduced into a heat cycle system, they can have adverse effects such as poor heat transfer in the condenser and evaporator and an increase in operating pressure, so their introduction must be minimized. Oxygen, a non-condensable gas, in particular, reacts with the working fluid and lubricating oil, promoting their decomposition. The concentration of non-condensable gases in the gas phase of the working fluid is preferably 1.5% by volume or less, and more preferably 0.5% by volume or less, based on the volume ratio of the working fluid. [Example]

[0060] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0061] (Evaluation of refrigeration cycle performance) The refrigeration cycle performance (refrigeration capacity and coefficient of performance) was evaluated as the cycle performance (capacity and efficiency) when a working fluid was applied to the refrigeration cycle system 10 of FIG. The evaluation was carried out by setting the average evaporation temperature of the working medium in the evaporator 14, the average condensation temperature of the working medium in the condenser 12, the degree of subcooling of the working medium in the condenser 12, and the degree of superheat of the working medium in the evaporator 14. In addition, it was assumed that there was no equipment efficiency or pressure loss in the piping or heat exchanger.

[0062] The refrigeration capacity Q and the coefficient of performance η can be calculated from the following equations (2) and (3) using the enthalpy h of each state (where the subscript of h indicates the state of the working medium). Q=h A -h D ···(2). η = refrigeration capacity / compression work =(h A -h D ) / (h B -h A ) ···(3).

[0063] The coefficient of performance (COP) represents the efficiency of a refrigeration cycle system, and a higher COP value means that a greater output (refrigeration capacity) can be obtained with a smaller input (amount of electricity required to operate the compressor).

[0064] On the other hand, refrigeration capacity refers to the ability to cool a load fluid, and the higher the refrigeration capacity, the more work can be done in the same system. In other words, a large refrigeration capacity means that the desired performance can be achieved with a small amount of working fluid, allowing the system to be made more compact.

[0065] The thermodynamic properties required for calculating the refrigeration cycle performance were calculated based on the generalized equation of state (Soave-Redlich-Kwong equation) based on the corresponding state principle and various thermodynamic equations. When property values ​​were not available, calculations were performed using an estimation method based on the atomic group contribution method.

[0066] [Example 1] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) was evaluated when a working fluid consisting of HFO-1123 and an HFC shown in Table 1 was applied to the refrigeration cycle system 10 of Figure 1. The evaluation was performed under the following conditions: the average evaporation temperature of the working fluid in the evaporator 14 was 0°C, the average condensation temperature of the working fluid in the condenser 12 was 50°C, the degree of subcooling of the working fluid in the condenser 12 was 5°C, and the degree of superheat of the working fluid in the evaporator 14 was 5°C.

[0067] Using the refrigeration cycle performance of HFC-134a as the standard, the relative performance (each working fluid / HFC-134a) of the refrigeration cycle performance (refrigeration capacity and coefficient of performance) of each working fluid to HFC-134a was calculated. The results for each working fluid are shown in Table 1.

[0068] [Table 1]

[0069] The results in Table 1 confirm that the addition of HFC-32 to HFO-1123 can improve the coefficient of performance and refrigeration capacity of HFO-1123. The addition of HFC-134a improved the coefficient of performance. The addition of HFC-125 decreased the coefficient of performance and refrigeration capacity, but maintained a refrigeration capacity of 1.0 or higher. HFC-125 has an excellent effect of suppressing flammability and can sufficiently suppress the flammability of the working fluid, so it is thought to be effective when flammability suppression is required for the working fluid.

[0070] [Example 2] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) was evaluated when a working fluid consisting of HFO-1123 and an HFO shown in Table 2 or Table 3 was applied to the refrigeration cycle system 10 of FIG. The evaluation was performed with the average evaporation temperature of the working medium in the evaporator 14 set to 0°C, the average condensation temperature of the working medium in the condenser 12 set to 50°C, the degree of subcooling of the working medium in the condenser 12 set to 5°C, and the degree of superheating of the working medium in the evaporator 14 set to 5°C.

[0071] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) of each working fluid relative to HFC-134a was determined using the refrigeration cycle performance of HFC-134a in Example 1 as the standard (each working fluid / HFC-134a). The results are shown for each working fluid in Tables 2 and 3.

[0072] [Table 2]

[0073] [Table 3]

[0074] The results in Tables 2 and 3 confirm that HFO-1123 has a higher refrigeration capacity than conventional HFOs. It was also confirmed that the addition of HFO can improve the coefficient of performance without significantly reducing refrigeration capacity.

[0075] [Example 3] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) was evaluated when a working fluid consisting of HFO-1123 and the hydrocarbons shown in Table 4 was applied to the refrigeration cycle system 10 of Figure 1. The evaluation was performed under the following conditions: the average evaporation temperature of the working fluid in the evaporator 14 was 0°C, the average condensation temperature of the working fluid in the condenser 12 was 50°C, the degree of subcooling of the working fluid in the condenser 12 was 5°C, and the degree of superheat of the working fluid in the evaporator 14 was 5°C.

[0076] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) of each working fluid relative to HFC-134a was determined using the refrigeration cycle performance of HFC-134a in Example 1 as the standard (each working fluid / HFC-134a). The results for each working fluid are shown in Table 4.

[0077] [Table 4]

[0078] The results in Table 4 confirm that the coefficient of performance of HFO-1123 can be improved by adding hydrocarbons to HFO-1123 without significantly reducing the refrigeration capacity.

[0079] [Example 4] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) was evaluated when a working fluid consisting of HFO-1123 and the HCFOs shown in Table 5 was applied to the refrigeration cycle system 10 of Figure 1. The evaluation was performed under the following conditions: the average evaporation temperature of the working fluid in the evaporator 14 was 0°C, the average condensation temperature of the working fluid in the condenser 12 was 50°C, the degree of subcooling of the working fluid in the condenser 12 was 5°C, and the degree of superheat of the working fluid in the evaporator 14 was 5°C.

[0080] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) of each working fluid relative to HFC-134a was determined using the refrigeration cycle performance of HFC-134a in Example 1 as the standard (each working fluid / HFC-134a). The results are shown for each working fluid in Table 5.

[0081] [Table 5]

[0082] The results in Table 5 confirm that the coefficient of performance of HFO-1123 can be improved by adding HCFO to HFO-1123 without significantly reducing the refrigeration capacity.

[0083] [Example 5] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) was evaluated when HFO-1123 was applied as the working fluid to the refrigeration cycle system 10 of FIG. The evaporation temperature of the working medium in the evaporator 14, the condensation temperature of the working medium in the condenser 12, the degree of subcooling of the working medium in the condenser 12, and the degree of superheat of the working medium in the evaporator 14 were set to the temperatures shown in Table 6.

[0084] The refrigeration cycle performance (refrigeration capacity and coefficient of performance) of HFO-1123 relative to HFC-134a (HFO-1123 / HFC-134a) was determined using the refrigeration cycle performance of HFC-134a in Example 1 as the standard. The results are shown in Table 6.

[0085] [Table 6] [Industrial Applicability]

[0086] The working fluid of the present invention is useful as a working fluid for heat cycles such as a refrigerant for a refrigerator, a refrigerant for an air conditioner, a working fluid for a power generation system (such as waste heat recovery power generation), a working fluid for a latent heat transport device (such as a heat pipe), and a secondary cooling medium. The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2011-112417, filed on May 19, 2011, are incorporated herein by reference as the disclosure of the specification of the present invention. [Explanation of symbols]

[0087] 10 Refrigeration cycle system

Claims

1. A working fluid for heat cycles containing 1,1,2-trifluoroethylene and a hydrofluorocarbon (excluding those containing difluoromethane), the content of the hydrofluorocarbon is 1 to 60 mass% in the working fluid for heat cycle (100 mass%), the content of the other working fluid other than 1,1,2-trifluoroethylene and the hydrofluorocarbon contained in the working fluid for heat cycle is such that the content of the other working fluid in a working fluid-containing composition (100% by mass) containing the working fluid for heat cycle is 30% by mass or less; Working medium for heat cycles.

2. 2. The working medium for heat cycle according to claim 1, wherein the hydrofluorocarbon comprises at least one selected from the group consisting of difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, pentafluorobutane, and heptafluorocyclopentane.

3. 2. The working medium for heat cycle according to claim 1, wherein the hydrofluorocarbon comprises at least one selected from the group consisting of 1,1-difluoroethane, 1,1,2,2-tetrafluoroethane, 1,1,1,2-tetrafluoroethane, and pentafluoroethane.

4. A heat cycle system using the working fluid for heat cycle according to any one of claims 1 to 3.

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