Working medium for thermal cycling, composition for thermal cycling system, and thermal cycling system

Abstract

A working medium for thermal cycling comprising (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene and an application thereof, wherein the total content of the (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene in the working medium for thermal cycling is 90.0 mass% or higher and the ratio shown by [(Z)-1-chloro-2,3,3,3-tetrafluoropropene]:[(E)-1,3,3,3-tetrafluoropropene] is 80.5:19.5 to 89.5:10.5 in terms of mass.

Description

Heat cycle working medium, composition for heat cycle system, and heat cycle system

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

[0002] Conventionally, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) have been used as working media for heat cycles. However, CFCs and HCFCs have been pointed out to have an impact on the ozone layer in the stratosphere. In particular, CFCs have a high ozone depletion potential (hereinafter also referred to as "ODP") and have already been completely phased out in accordance with the Montreal Protocol. For HCFCs, a complete phase-out has been decided in 2020. Therefore, hydrofluorocarbons (HFCs), which have less impact on the ozone layer, have been used as working media for heat cycles instead of CFCs and HCFCs. On the other hand, HFCs are considered to have a problem because their global warming potential (hereinafter also referred to as "GWP") is relatively high.

[0003] In contrast, as working media with less impact on the ozone layer and low GWP, hydrofluoroolefins (HFOs), hydrochlorofluoroolefins (HCFOs), and chlorofluoroolefins (CFOs) having a carbon-carbon double bond are attracting attention. Since these working media have a carbon-carbon double bond, they are easily decomposed by OH radicals in the atmosphere. In this specification, saturated HFCs are referred to as HFCs unless otherwise specified, and are used separately from HFOs. [[ID=I0]]

[0004] Among them, in particular, (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)) has a low ODP and GWP, a low halogen ratio in one molecule, so it has low flammability, a relatively low boiling point, and a high critical temperature. Therefore, it is promising as a working medium for a Rankine cycle or a heat cycle. For example, Patent Document 1 describes a working medium for a heat cycle containing HCFO-1224yd(Z) and (E)-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)) at a specific ratio.

[0005] International Publication No. 2019 / 022138

[0006] Working fluids using HCFO-1224yd(Z) are used in applications such as high-temperature heat pumps because they have a low environmental impact and are non-flammable. Working fluids for high-temperature heat pumps are required to have high volumetric capacity in heating and a small temperature difference between the dew point and boiling point of the working fluid under atmospheric pressure (hereinafter also referred to as "temperature glide under atmospheric pressure"). However, it is difficult to obtain high volumetric capacity in heating with HCFO-1224yd(Z) alone. Furthermore, in the case of mixtures containing multiple compounds, such as the working fluid for thermal cycling described in Patent Document 1, a large temperature glide under atmospheric pressure makes it difficult for the mixture to exhibit its full potential, not only in high-temperature heat pump applications. Therefore, when applying a working fluid for thermal cycling as a working fluid for high-temperature heat pumps, it is necessary to achieve both a small temperature glide under atmospheric pressure and high volumetric capacity in heating.

[0007] The objective of one embodiment of this disclosure is to provide a thermal cycle working fluid that achieves both a small temperature glide (the temperature difference between the dew point and boiling point of the working fluid under atmospheric pressure) and high volumetric capacity for heating. The objective of another embodiment of this disclosure is to provide a thermal cycle system composition and a thermal cycle system using the above-mentioned thermal cycle working fluid.

[0008] This disclosure includes the following aspects: <1> A thermal cycle working medium comprising (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene, wherein the total content of (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene contained in the thermal cycle working medium is 90.0% by mass or more, and the ratio expressed as (Z)-1-chloro-2,3,3,3-tetrafluoropropene:(E)-1,3,3,3-tetrafluoropropene is 80.5:19.5 to 89.5:10.5 by mass. <2> The thermal cycle working fluid according to <1>, wherein the ratio represented by (Z)-1-chloro-2,3,3,3-tetrafluoropropene:(E)-1,3,3,3-tetrafluoropropene is 81.0:19.0 to 89.0:11.0 by mass. <3> The thermal cycle working fluid according to <1> or <2>, wherein the total content of (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene contained in the thermal cycle working fluid is 99.0% by mass or more. <4> A thermal cycle system composition comprising the thermal cycle working fluid according to any one of <1> to <3>. <5> The thermal cycle system composition according to <4>, comprising a lubricating oil. <6> The thermal cycle system composition according to <4> or <5>, comprising a stabilizer that suppresses the deterioration of the thermal cycle working fluid. <7> A thermal cycle system comprising: a thermal cycle working medium described in any one of <1> to <3>; a compressor for compressing the thermal cycle working medium; a condenser for exchanging heat between the thermal cycle working medium discharged from the compressor and a fluid to be heated; a depressurizing device for reducing the pressure of the thermal cycle working medium discharged from the condenser; and an evaporator for exchanging heat between the thermal cycle working medium discharged from the depressurizing device and a fluid to be cooled, wherein the condenser is controlled to have a condensation temperature of 60°C or higher.

[0009] According to one embodiment of the present disclosure, a thermal cycle working fluid is provided that achieves both a small temperature glide, which is the temperature difference between the dew point and boiling point of the working fluid under atmospheric pressure, and high volumetric capacity in heating. According to another embodiment of the present disclosure, a thermal cycle system composition and a thermal cycle system using the above thermal cycle working fluid are provided.

[0010] Figure 1 is a schematic diagram showing an example of a heat pump system. Figure 2 is a cycle diagram showing the state changes of the working fluid for the thermal cycle in the heat pump system, plotted on a pressure-enthalpy diagram.

[0011] In this disclosure, numerical ranges indicated using "~" mean a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. In this disclosure, the amount of each component means the total amount of multiple substances if there are multiple substances corresponding to each component, unless otherwise specified. In this disclosure, pressure refers to absolute pressure and is 0.101325 MPa at atmospheric pressure.

[0012] In this disclosure, for halogenated hydrocarbons, the abbreviation of the compound is indicated in parentheses after the compound name; however, in this disclosure, the abbreviation may be used instead of the compound name as needed. Furthermore, (E) attached to the name and abbreviation of a compound having geometric isomers indicates the E-isomer (trans isomer), and (Z) indicates the Z-isomer (cis isomer). In the name and abbreviation of a compound, if the E-isomer or Z-isomer is not specified, the name and abbreviation refer to a general term including the E-isomer, the Z-isomer, and mixtures of the E-isomer and Z-isomer.

[0013] In this disclosure, the term "working medium" refers to a medium that carries heat and is a concept that encompasses refrigerant compositions and heat transfer compositions. The refrigerant composition is primarily a medium responsible for cooling a heat source, but may also be used as a medium responsible for heating. Similarly, the heat transfer composition is primarily a medium responsible for heating, but may also be used as a medium responsible for cooling a heat source. The working medium of this disclosure is preferably used for thermal cycling. Specifically, the working medium of this disclosure is preferably used in a thermal cycling system in which a series of changes occur, such as a change of state using heat absorption and heat release, and then returning to the initial state.

[0014] In this disclosure, “thermal cycle system” means a system comprising a thermal cycle system and a thermal cycle system, wherein a thermal cycle working fluid (hereinafter also simply referred to as the working fluid) is introduced into the thermal cycle system to make it capable of performing a thermal cycle. “Thermal cycle system” means a thermal cycle system designed so that heat exchange (thermal cycle) can be performed between the working fluid and other substances other than the working fluid by the flow of the working fluid within the system.

[0015] In this disclosure, "high-temperature heat pump" means a thermal cycle system in which the condensation temperature of the working medium is controlled to 60°C or higher.

[0016] In this disclosure, unless otherwise specified, GWP refers to the 100-year value from the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report (AR6). For mixtures, the GWP is calculated as a weighted average based on compositional mass. When considering the GWP for mixtures, components with a GWP of 1 or less are treated as 1 in the calculation.

[0017] [Working medium] A working medium according to one embodiment of the present disclosure comprises (Z)-1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd(Z)) and (E)-1,3,3,3-tetrafluoropropene (HFO-1234ze(E)), wherein the total content of HCFO-1224yd(Z) and HFO-1234ze(E) contained in the working medium is 90.0% by mass or more, and the ratio expressed as HCFO-1224yd(Z):HFO-1234ze(E) is 80.5:19.5 to 89.5:10.5 by mass.

[0018] The working fluid of this embodiment achieves both low temperature glide under atmospheric pressure and high volumetric capacity in heating. Specifically, compared to cases where the ratio of HCFO-1224yd(Z) to the total amount of HCFO-1224yd(Z) and HFO-1234ze(E) is less than 80.5% by mass or greater than 89.5% by mass, it achieves both low temperature glide under atmospheric pressure and high volumetric capacity in heating. Therefore, the working fluid of this embodiment can be applied, for example, as a working fluid for high-temperature heat pumps.

[0019] The working fluid of this embodiment is used in combination with a thermal cycle system. Alternatively, these working fluids may be combined with compounds other than the working fluid to form a thermal cycle system composition containing these working fluids, which can then be used in the thermal cycle system. Next, the components contained in the working fluid described above will be explained.

[0020] The working medium of this embodiment comprises at least HCFO-1224yd(Z) and HFO-1234ze(E), and may optionally contain other components besides HCFO-1224yd(Z) and HFO-1234ze(E).

[0021] (HCFO-1224yd(Z)) HCFO-1224yd has a halogen that suppresses flammability and a carbon-carbon double bond in its molecule that is easily decomposed by OH radicals in the atmosphere. HCFO-1224yd has two geometric isomers: HCFO-1224yd(Z) and HCFO-1224yd(E). HCFO-1224yd(Z) has higher chemical stability than HCFO-1224yd(E). The working medium of this embodiment contains at least HCFO-1224yd(Z). The boiling point of HCFO-1224yd(Z) is 14.9°C and its GWP is 0.88. The above GWP value for HCFO-1224yd(Z) is the value described in Tokuhashi, K. "Rate Constants for the Reactions of OH Radical with the (E) / (Z) Isomers of CF3CF=CHCl and CHF2CF=CHCl", J. Phys. Chem. A, Volume 122, Issue 12, (2018).

[0022] (HFO-1234ze(E)) HFO-1234ze(E) has a carbon-carbon double bond in its molecule that is easily decomposed by OH radicals in the atmosphere. The boiling point of HFO-1234ze(E) is -19.0°C and its GWP is 0.12.

[0023] In the working medium of this embodiment, the ratio of HCFO-1224yd(Z) to the total amount of HCFO-1224yd(Z) and HFO-1234ze(E) is 80.5 to 89.5% by mass. From the viewpoint of achieving both low temperature glide under atmospheric pressure and high volume capacity in heating, 81.0 to 89.0% by mass is preferred, and 82.0 to 88.0% by mass is more preferred.

[0024] In the working medium of this embodiment, the total content of HCFO-1224yd(Z) and HFO-1234ze(E) relative to the total amount of working medium is 90.0% by mass or more. From the viewpoint of achieving both low temperature glide under atmospheric pressure and high volume capacity in heating, 92.5 to 100.0% by mass is preferred, 95.0 to 100.0% by mass is more preferred, 99.0 to 100.0% by mass is even more preferred, and 100.0% by mass is particularly preferred.

[0025] If the working medium of this embodiment contains an optional component, the optional component may be contained in a proportion of 10.0% by mass or less relative to the total amount of the working medium. When an optional component is contained, the proportion of the optional component to the total amount of the working medium is preferably 10.0% by mass or less, more preferably 7.5% by mass or less, and even more preferably 5.0% by mass or less. The lower limit of the proportion of the optional component to the total amount of the working medium is not particularly limited, and for example, 1.0% by mass can be cited. If the working medium of this embodiment contains an optional component, the total content of HCFO-1224yd(Z) and HFO-1234ze(E) relative to the total amount of the working medium may be 90.0 to 99.0% by mass, 92.5 to 99.0% by mass, or 95.0 to 99.0% by mass.

[0026] (Optional components) Examples of optional components include known compounds used as working fluids, specifically, working fluids such as HFCs, HFOs other than HFO-1234ze(E), HCFOs other than HCFO-1224yd (hereinafter also referred to as "other HCFOs"), and trans-1,2-dichloroethylene. When the working fluid of this embodiment contains optional components, it is preferable that the optional component includes 2,3,3,3-tetrafluoropropene (HFO-1234yf) among HFOs other than HFO-1234ze(E).

[0027] (HFO-1234yf) HFO-1234yf has a carbon-carbon double bond in its molecule that is easily decomposed by OH radicals in the atmosphere. The boiling point of HFO-1234yf is -29.5°C and its GWP is 0.04.

[0028] When the working medium of this embodiment contains HFO-1234yf, the content of HFO-1234yf relative to the total amount of the working medium is 10.0% by mass or less. From the viewpoint of achieving both low temperature glide at atmospheric pressure and high volumetric capacity in heating, 1.0 to 10.0% by mass is preferred, 1.0 to 5.0% by mass is more preferred, and 1.0 to 1.5% by mass is even more preferred. When the working medium of this embodiment contains HFO-1234yf, the total content of HCFO-1224yd(Z) and HFO-1234ze(E) relative to the total amount of the working medium is 90% by mass or more. From the viewpoint of achieving both low temperature glide at atmospheric pressure and high volumetric capacity in heating, 90.0 to 99.0% by mass is preferred, 95.0 to 99.0% by mass is more preferred, and 98.5 to 99.0% by mass is even more preferred.

[0029] (HFCs) HFCs have a higher GWP than HCFO-1224yd, HFO-1234ze(E), and HFO-1234yf. Specifically, HFCs with 1 to 5 carbon atoms are examples of HFCs with relatively low environmental impact such as GWP. HFCs may be linear, branched, or cyclic. Examples of HFCs include difluoromethane, difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane, pentafluoropropane, hexafluoropropane, heptafluoropropane, pentafluorobutane, and heptafluorocyclopentane. HFCs may be used individually or in combination of two or more types.

[0030] (HFO) HFOs other than HFO-1234ze(E) and HFO-1234yf (hereinafter also referred to as "other HFOs") include HFO-1336mzz(Z), HFO-1336mzz(E), 1,1-difluoroethylene (HFO-1132a), (E)-1,2-difluoroethylene (HFO-1132(E)), (Z)-1,2-difluoroethylene (HFO-1132(Z)), trifluoroethylene (HFO-1123), 2-fluoropropene (HFO-1261yf), 1-fluoropropene (HFO-1261ze), 1,2-difluoropropane (HFO-1252ye), 3,3-difluoropropene (HFO-1252zf), and 1,1,2-trifluoroethylene. Examples include olopropene (HFO-1243yc), 1,2,3-trifluoropropene (HFO-1243ye), 1,3,3-trifluoropropene (HFO-1243ze), 3,3,3-trifluoropropene (HFO-1243zf), (Z)-1,3,3,3-tetrafluoropropene (HFO-1234ze(Z)), 1,1,2,3,3-pentafluoropropene (HFO-1225yc), (E)-1,2,3,3,3-pentafluoropropene (HFO-1225ye(E)), (Z)-1,2,3,3,3-pentafluoropropene (HFO-1225ye(Z)), and 1,1,3,3,3-pentafluoropropene (HFO-1225zc). Other preferred HFOs include HFO-1234ze(Z) and HFO-1243zf. These other HFOs may be used individually or in combination of two or more. The boiling point of HFO-1234ze(Z) is 9.73°C, and its GWP is 0.03.

[0031] (HCFO) Other HCFOs include HCFO-1224yd(E), 1-chloro-2,2-difluoroethylene (HCFO-1122), 1,2-dichlorofluoroethylene (HCFO-1121), 1-chloro-2-fluoroethylene (HCFO-1131), 2-chloro-1,1,3-trifluoropropene (HCFO-1233xc), 2-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 1-chloro-2,3,3-trifluoro-1-propene (HCFO-1233yd), (E)-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(E)), and (Z)-1-chloro-3,3,3-trifluoropropene (HCFO-1233zd(Z)). As for other HCFOs, HCFO-1233zd(E) is preferred due to its high critical temperature and excellent durability. Other HCFOs may be used individually or in combination of two or more types.

[0032] (Other optional components) In addition to the components listed above, the working medium of this embodiment may also contain carbon dioxide, hydrocarbons, CFO, water, air, and other unavoidable components. Preferably, the other optional components have little impact on the ozone layer and minimal impact on global warming.

[0033] Examples of hydrocarbons include propane, propylene, cyclopropane, butane, isobutane, pentane, and isopentane. Hydrocarbons may be used individually or in combination of two or more. The presence of hydrocarbons improves the solubility of mineral-based lubricants in the working medium. When the working medium contains hydrocarbons, the hydrocarbon content is preferably 10.0% by mass or less, and more preferably 5.0% by mass or less, based on 100.0% by mass of the working medium, from the viewpoint of flammability.

[0034] Examples of CFOs include chlorofluoropropene and chlorofluoroethylene. Preferred 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), as they easily suppress the flammability of the working fluid without significantly reducing its cycle performance. A single CFO may be used, or two or more may be used in combination.

[0035] The water content in the working medium, as measured by Karl Fischer coulometric titration, is preferably 20 ppm by mass or less, and particularly preferably 15 ppm by mass or less, relative to the total amount of the working medium. When the water content is 20 ppm by mass or less, freezing in the capillary tube of the thermal cycle system, hydrolysis of the working medium and lubricating oil, material degradation due to acidic components generated in the apparatus, and the generation of contaminants are suppressed.

[0036] The air content in the gas phase of the working fluid at 25°C is preferably 3.5% by volume or less, more preferably 2.5% by volume or less, even more preferably 2.0% by volume or less, and particularly preferably 1.5% by volume or less, as measured by a gas chromatograph. When the air content is 3.5% by volume or less, discoloration and rust formation on the metal surface that comes into contact with the working fluid in the thermal cycle system are suppressed. This is presumed to be because the reaction of oxygen in the air with the working fluid or lubricating oil suppresses the decomposition of the metal.

[0037] The working medium may contain impurities produced as by-products during the manufacturing of the working medium, solvents used in the manufacturing process, and other unavoidable components. From the viewpoint of ensuring stability, the total content of these other unavoidable components is preferably 1.5% by mass or less, more preferably 1.3% by mass or less, and even more preferably 1.0% by mass or less, based on the total amount of the working medium. From the viewpoint of simplifying the purification process in the manufacturing of the working medium, the total content of these other unavoidable components may be 50.0 ppm by mass or more, or 100.0 ppm by mass or more.

[0038] Other unavoidable components include 1,1,2,2,3-pentafluoro-1,3-dichloropropane (HCFC-225cb), 1,1,1,2-tetrafluoropropane (HFC-254eb), 1,3,3,3-tetrafluoropropane (HFC-254fb), 1,1,2,3-tetrafluorobutane (HFC-374pee), CFO-1214ya, HCFO-1224yd(E), (Z)2-chloro-1,3,3,3-tetrafluoropropene (HCFO-1224xe(Z)), (E)-2-chloro-1,3,3,3-tetrafluoropropene (HCFO-1224xe(E)), HCFO-1233xf, HFO-1234yf, H Examples include FO-1234ze(Z), HFO-1354yf, HCFO-1233zd(E), HCFO-1233zd(Z), HCFO-1233xc, fluorinated hydrocarbons represented as C4H4F4, 2-chloro-1,1,1,2-tetrafluoropropane (HCFC-244bb), HFC-245fa, 2-chloro-1,1,3,3,3-pentafluoro-1-propene (CFO-1215xc), 3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC-225ca), 1,1,1,2,2,3,3-heptafluoropropane (FC-227ca), methanol, ethanol, acetone, chloroform, hexane, and the like.

[0039] (Temperature glide of the working fluid under atmospheric pressure) In mixtures containing multiple compounds, such as the working fluid in this embodiment, it is necessary to consider the temperature difference between the dew point and the boiling point under atmospheric pressure, i.e., the temperature glide under atmospheric pressure. For individual compounds and azeotropic mixtures, the temperature glide under atmospheric pressure is 0, and for pseudo-azeotropic mixtures that exhibit behavior similar to azeotropic mixtures during evaporation (little change in gas-liquid composition), the temperature glide under atmospheric pressure is extremely close to 0. On the other hand, the working fluid in this embodiment is a mixture containing HCFO-1224yd(Z) and HFO-1234ze(E), and since it is a non-azeotropic mixed fluid that does not form an azeotrope at any mixing ratio, the above-mentioned temperature glide under atmospheric pressure occurs. Here, if the temperature glide under atmospheric pressure of the mixture containing HCFO-1224yd(Z) and HFO-1234ze(E) becomes large, the temperature glide in the evaporator and condenser of the cycle will also become large when the above mixture is applied as the working fluid in a thermal cycle system. Therefore, when the pressure in the mixture in the condenser and evaporator is constant, the temperature of the mixture decreases from the inlet to the outlet in the condenser, and increases from the inlet to the outlet in the evaporator, which tends to reduce the heat transfer performance in the heat exchanger. Consequently, from the viewpoint of obtaining an energy-efficient thermal cycle system, a smaller temperature glide under atmospheric pressure is preferable.

[0040] The temperature glide of the working medium in this embodiment under atmospheric pressure is preferably 10.2°C or less, more preferably 10.1°C or less, and even more preferably 10.0°C or less, from the viewpoint of equipment operation, i.e., heat exchanger efficiency. The lower limit of the temperature glide of the working medium in this embodiment under atmospheric pressure is not particularly limited, and for example, 7.2°C can be cited.

[0041] The temperature glide of the working medium under atmospheric pressure is determined by the difference between the dew point of the working medium under atmospheric pressure and the boiling point of the working medium under atmospheric pressure, as described above. The dew point of the working medium under atmospheric pressure and the boiling point of the working medium under atmospheric pressure are determined using the National Institute of Science and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10.0).

[0042] <Composition for Thermal Cycle System> When applied to a thermal cycle system, the working medium of this embodiment can be used as the composition for the thermal cycle system of this embodiment including the same. The composition for the thermal cycle system of this embodiment may directly use the working medium of the above-described embodiment, or may contain a lubricating oil in addition to the working medium of the above-described embodiment. Further, the composition for the thermal cycle system of this embodiment may contain known additives such as a stabilizer for suppressing deterioration of the working medium and a leak detection substance. These lubricating oils and additives can also be used in combination.

[0043] (Lubricating Oil) As the lubricating oil, known lubricating oils conventionally used in the working medium composition can be adopted without particular limitation together with the working medium composed of halogenated hydrocarbons. Specifically, examples of the lubricating oil include oxygen-containing synthetic oils (such as ester-based lubricating oils and ether-based lubricating oils), fluorine-based lubricating oils, mineral-based lubricating oils, and hydrocarbon-based synthetic oils.

[0044] Examples of the ester-based lubricating oil include dibasic acid ester oil, polyol ester oil, complex ester oil, and polyol carbonate ester oil. Examples of the ether-based lubricating oil include polyvinyl ether oil and polyoxyalkylene oils such as polyalkylene glycol oil. Examples of the fluorine-based lubricating oil include compounds in which hydrogen atoms of synthetic oils (mineral oils, polyalpha-olefins, alkylbenzenes, alkylnaphthalenes, etc. described later) are replaced with fluorine atoms, perfluoropolyether oil, and fluorinated silicone oil.

[0045] Examples of mineral-based lubricants include paraffinic mineral oils and naphthenic mineral oils, which are obtained by refining lubricant fractions obtained by atmospheric or vacuum distillation of crude oil, using an appropriate combination of refining processes (solvent delamination, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, clay treatment, etc.). Examples of hydrocarbon-based synthetic oils include poly-α-olefins, alkylbenzenes, and alkylnaphthalenes.

[0046] The lubricating oil may be used alone or in combination of two or more types. From the viewpoint of compatibility with the working medium, one or more lubricating oils selected from ester-based lubricating oils, ether-based lubricating oils, and mineral-based lubricating oils are preferred, one or more selected from polyol ester oils, polyvinyl ether oils, polyalkylene glycol oils, paraffin-based mineral oils, and naphthenic mineral oils are more preferred, and one or more selected from polyol ester oils, polyvinyl ether oils, and polyalkylene glycol oils are preferred. The amount of lubricating oil added should not significantly reduce the effects of the present invention, and is preferably 10 to 100 parts by mass, and more preferably 20 to 50 parts by mass, per 100 parts by mass of the working medium.

[0047] (Stabilizers) Stabilizers are components that improve the stability of the working fluid against heat and oxidation. As stabilizers, known stabilizers used in thermal cycle systems, such as oxidation resistance improvers, heat resistance improvers, and metal deactivators, can be used without particular limitation, along with working fluids made of halogenated hydrocarbons.

[0048] Examples of the oxidation resistance improver and heat resistance improver include N,N'-diphenyl-p-phenylenediamine, 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), and the like. The oxidation resistance improver and heat resistance improver may be used alone or in combination of two or more kinds.

[0049] Examples of the metal deactivator include imidazole, benzimidazole, 2-mercaptobenzothiazole, 2,5-dimethylmercapto-thiadiazole, salicylidene-propylenediamine, pyrazole, benzotriazole, tolutriazole, 2-methylbenzimidazole, 3,5-dimethylpyrazole, methylenebis-benzotriazole, an organic acid or its ester, a primary, secondary or tertiary aliphatic amine, an amine salt of an organic acid or an inorganic acid, a heterocyclic nitrogen-containing compound, an amine salt of an alkyl acid phosphate or its derivative, and the like.

[0050] The addition amount of the stabilizer may be in a range that does not significantly reduce the effects of the present invention, and is preferably 5 parts by mass or less, more preferably 1 part by mass or less, based on 100 parts by mass of the working medium.

[0051] (Leak detection substance) Examples of the leak detection substance include an ultraviolet fluorescent dye, an odor gas, an odor masking agent, and the like. Examples of the ultraviolet fluorescent dye include those described in U.S. Patent No. 4,249,412, JP-T-10-502737, JP-T-2007-511645, JP-T-2008-500437, JP-T-2008-531836, and the like, and known ultraviolet fluorescent dyes conventionally used in a thermal cycle system together with a working medium composed of a halogenated hydrocarbon.

[0052] Examples of odor masking agents include those described in Japanese Patent Publication No. 2008-500437 and Japanese Patent Publication No. 2008-531836, as well as other known fragrances that have been conventionally used in thermal cycle systems together with working media consisting of halogenated hydrocarbons. When a leak detection substance is used, a solubilizer may be used to improve the solubility of the leak detection substance in the working media. Examples of solubilizers include those described in Japanese Patent Publication No. 2007-511645, Japanese Patent Publication No. 2008-500437 and Japanese Patent Publication No. 2008-531836. The amount of leak detection substance added should not significantly reduce the effect of the present invention, 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 media.

[0053] (Uses of the composition for thermal cycle systems) The composition for thermal cycle systems of this embodiment is used in thermal cycle systems. The thermal cycle system to which the composition for thermal cycle systems of this embodiment is applied may be a heat pump system that utilizes the heat obtained from a condenser, or a refrigeration cycle system that utilizes the cold energy obtained from an evaporator.

[0054] Examples of thermal cycle systems include heating and hot water supply equipment, air conditioning equipment, power generation systems, heat transport devices, refrigeration and freezing equipment, and secondary coolers. Among these, thermal cycle systems are preferably used as air conditioning equipment, which is often installed outdoors, because they can stably and safely perform thermal cycle performance even in higher temperature operating environments. Thermal cycle systems are also preferably used as heating and hot water supply equipment. Among heating and hot water supply equipment and air conditioning equipment, thermal cycle systems are preferably used as heat pumps, and more preferably as high-temperature heat pumps.

[0055] Examples of heating and hot water supply equipment include heat pump water heaters, heat pump hot water heaters, heat pump hot air heaters, steam-heated heat pumps, and waste heat recovery heat pumps. Among these, steam-heated heat pumps and waste heat recovery heat pumps are preferred as heating and hot water supply equipment.

[0056] Examples of air conditioning equipment include room air conditioners, packaged air conditioners (packaged air conditioners for shops, buildings, and facilities), gas engine heat pumps, train air conditioning systems, and automobile air conditioning systems. Examples of automobile air conditioning systems include air conditioning systems for gasoline vehicles, hybrid vehicles, electric vehicles, or hydrogen vehicles.

[0057] Refrigeration and freezing equipment specifically includes display cases (refrigerated display cases, frozen display cases, etc.), refrigerators, freezers, water coolers, refrigeration and freezing units, freezers for refrigerated and frozen warehouses, chillers (chilling units), turbo chillers, screw chillers, vending machines, and ice makers.

[0058] As a power generation system, a Rankine cycle system is preferred. Specifically, an example of such a power generation system is one in which a working medium is heated in an evaporator using geothermal energy, solar heat, or waste heat in the medium to high temperature range of approximately 50°C to 200°C, the working medium becomes a high-temperature, high-pressure vapor, and is adiabatically expanded in an expander, and the work generated by this adiabatic expansion drives a generator to produce electricity.

[0059] As a heat transport device, a latent heat transport device is preferred. Examples of latent heat transport devices include heat pipes and two-phase sealed thermal siphon 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 applied to relatively small cooling devices, such as cooling devices for heat-generating parts of semiconductor elements and electronic equipment. Two-phase sealed thermal siphon devices do not require a wig and have a simple structure, so they are widely used in gas-gas heat exchangers, road snow melting acceleration, and de-icing prevention.

[0060] The thermal cycle system to which the thermal cycle system composition of this embodiment is applied is preferably a heat pump system that utilizes the heat obtained from a condenser, and more preferably a high-temperature heat pump system in which the condensation temperature of the working medium in the condenser is controlled to 60°C or higher. An example of a thermal cycle system to which the thermal cycle system composition of this embodiment is applied will be described below.

[0061] [Thermal cycle system] The thermal cycle system of the present disclosure comprises the working medium according to the present embodiment described above, a compressor for compressing the working medium, a condenser for exchanging heat between the working medium discharged from the compressor and a fluid to be heated, a depressurizing device for reducing the pressure of the working medium discharged from the condenser, and an evaporator for exchanging heat between the working medium discharged from the depressurizing device and a fluid to be cooled.

[0062] The thermal cycle system to which the working fluid is applied may be a heat pump device that utilizes the heat obtained from a condenser, or a refrigeration cycle device that utilizes the cold energy obtained from an evaporator. The thermal cycle system of this disclosure may be a direct expansion type or an indirect expansion type. Examples of indirect expansion types include flooded evaporators.

[0063] A thermal cycle involves a series of steps: (1) compressing the working fluid in a gaseous state using a compressor; (2) cooling it in a condenser to convert it into a high-pressure liquid state; (3) reducing the pressure using an expansion valve, which is an example of a pressure reducing device; and (4) vaporizing it at a low temperature in an evaporator to remove heat through the latent 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 working fluid in a gaseous state, and can be selected based on heat capacity, compression ratio, and size.

[0064] <Cycle Performance> Cycle performance, a property required when applying a working fluid to a thermal cycle system, can be evaluated by its capacity per unit volume. In the case of a heat pump system, the capacity is the heating capacity. Hereinafter, the heating capacity per unit volume in a heat pump system, that is, the volumetric capacity in heating, will also be called "CAP". In addition to the cycle performance mentioned above, another evaluation item when applying a working fluid to a heat pump system is the temperature difference between the dew point and boiling point of the working fluid under atmospheric pressure (i.e., the temperature glide under atmospheric pressure). Specifically, the cycle performance is calculated, for example, using the temperature conditions and methods described later. The temperature glide under atmospheric pressure is an absolute value, and CAP is evaluated by converting it to a relative value based on the value of HFO-1224yd(Z). Hereinafter, the CAP of the working fluid being evaluated, when the CAP of a working fluid of 100 mass% HCFO-1224yd(Z) is set to 1.00, will also be called "CAP (relative value)".

[0065] (High-Temperature Heat Pump System) As an example of a thermal cycle system, a high-temperature heat pump system will be described. A heat pump system is a system that heats a fluid to be heated to a higher temperature by transferring thermal energy to the fluid to be heated in a condenser through a working fluid. The fluid to be heated and the fluid to be cooled, which will be described later, may be a gas or a liquid. Examples of gases include air. Examples of liquids include water, brine, and silicone oil. Furthermore, a high-temperature heat pump system is a type of heat pump system in which the condensation temperature of the working fluid in the condenser is controlled to be 60°C or higher.

[0066] In this disclosure, condensation temperature refers to the temperature at which the vapor of the working medium releases heat and becomes a liquid during the condensation process of a thermal cycle system. The condensation temperature can be determined by measuring the temperature at the condenser inlet and / or condenser outlet. For single media and azeotropic mixed media, the condensation temperature is constant, but for non-azeotropic mixed media, it is the average temperature of the condensation start temperature and the condensation completion temperature, and is calculated as "condensation temperature = (condensation start temperature + condensation completion temperature) / 2". Also in this disclosure, evaporation temperature refers to the temperature at which the working medium absorbs heat and becomes vapor during the evaporation process of a thermal cycle system. The evaporation temperature can be determined by measuring the temperature at the evaporator inlet and / or evaporator outlet. For single media and azeotropic mixed media, the evaporation temperature is constant, but for non-azeotropic mixed media, it is the average temperature of the evaporation start temperature and the evaporation completion temperature, and is calculated as "evaporation temperature = (evaporation start temperature + evaporation completion temperature) / 2". The difference between the condensation temperature and the evaporation temperature (condensation temperature - evaporation temperature) is also called the temperature lift.

[0067] Figure 1 is a schematic diagram showing an example of a high-temperature heat pump system of the present disclosure. The high-temperature heat pump system 10 is a system that is schematically configured to include a compressor 11 that compresses working medium vapor A into high-temperature, high-pressure working medium vapor B, a condenser 12 that cools the working medium vapor B discharged from the compressor 11 by heat exchange with the fluid to be heated F and liquefies it into a low-temperature, high-pressure working medium C, an expansion valve 13 that expands the working medium C discharged from the condenser 12 into a low-temperature, low-pressure working medium D, an evaporator 14 that heats the working medium D discharged from the expansion valve 13 by heat exchange with the fluid to be cooled E to produce high-temperature, low-pressure working medium vapor A, a pump 15 that supplies the fluid to be cooled E to the evaporator 14, and a pump 16 that supplies the fluid to be heated F to the condenser 12.

[0068] In the high-temperature heat pump system 10, the following cycles (i) to (iv) are repeated: (i) The working medium vapor A discharged from the evaporator 14 is compressed in the compressor 11 to become high-temperature, high-pressure working medium vapor B (hereinafter referred to as the "AB process"). (ii) The working medium vapor B discharged from the compressor 11 is cooled in the condenser 12 by the heated fluid F and liquefied to become low-temperature, high-pressure working medium C. At this time, the heated fluid F is heated to become heated fluid F' and discharged from the condenser 12 (hereinafter referred to as the "BC process"). (iii) The working medium C discharged from the condenser 12 is expanded in the expansion valve 13 to become low-temperature, low-pressure working medium D (hereinafter referred to as the "CD process"). (iv) The working medium D discharged from the expansion valve 13 is heated in the evaporator 14 by the cooled fluid E to become high-temperature, low-pressure working medium vapor A. In this process, the fluid to be cooled E is cooled to become the fluid to be cooled E', which is then discharged from the evaporator 14 (hereinafter referred to as the "DA process").

[0069] The high-temperature heat pump system 10 is a cyclic system consisting of adiabatic / isentropic changes, isenthalpy changes, and isobaric changes. When the state changes of the working fluid are plotted on the pressure-enthalpy curve diagram shown in Figure 2, they can be represented with peaks A, B, C, and D.

[0070] The AB process is a process in which adiabatic compression is performed in the compressor 11 to convert low-temperature, low-pressure working medium vapor A into high-temperature, high-pressure working medium vapor B, and is shown by the AB line in Figure 2. As described later, working medium vapor A is introduced into the compressor 11 in a superheated state, and the resulting working medium vapor B is also superheated vapor. The compressor intake gas density is the density (ρs) in state A in Figure 2. The compressor discharge gas temperature (discharge temperature) is the temperature (Tx) in state B in Figure 2, and is the highest temperature in the heating cycle. The compressor discharge pressure (discharge pressure) is the pressure (Px) in state B in Figure 2, and is the highest pressure in the heating cycle. Since the BC process is isobaric cooling, the discharge pressure is the same value as the condensation pressure (Pc). Therefore, in Figure 2, for convenience, the condensation pressure is shown as Px.

[0071] The BC process is a process in which isobaric cooling is performed in the condenser 12 to convert the high-temperature, high-pressure working medium vapor B into a low-temperature, high-pressure working medium C, and is shown by the BC line in Figure 2. The pressure at this time is the condensation pressure. Of the intersections of the pressure-enthalpy line and the BC line, the intersection T1 on the high-enthalpy side is the condensation start temperature, and the intersection T2 on the low-enthalpy side is the condensation completion temperature. Here, the temperature glide in the condenser when the working medium is a non-azeotropic mixed medium is shown as the difference between T1 and T2.

[0072] In the BC process, the condensation temperature is 60°C or higher, preferably 65°C or higher, more preferably 70°C or higher, and even more preferably 75°C or higher, from the viewpoint of being able to heat the heating medium to a higher temperature. Furthermore, there is no particular upper limit to the condensation temperature. The condensation temperature is preferably below the critical temperature of the working medium. The critical temperature is the temperature at the end point of the high-pressure, high-temperature side of the saturated liquid line and saturated vapor line. Above the critical temperature, neither evaporation nor liquefaction occurs, the distinction between the liquid phase and the gas phase disappears, and no phase change occurs. By keeping the temperature of the working medium below the critical temperature, the working medium can be liquefied (condensed), and the refrigeration performance can be maintained.

[0073] The CD process is a process in which isenthalpy expansion is performed in the expansion valve 13, converting the low-temperature, high-pressure working medium C into a low-temperature, low-pressure working medium D, and is shown by the CD line in Figure 2. If the temperature of the low-temperature, high-pressure working medium C is denoted by T3, then T2-T3 represents the degree of supercooling (SC) of the working medium in cycles (i) to (iv).

[0074] 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 the high-temperature, low-pressure working medium vapor A, and is shown by the DA line in Figure 2. The pressure at this time is the evaporation pressure. Of the intersections of the pressure-enthalpy line and the DA line, the intersection T4 on the low-enthalpy side is the evaporation start temperature, and the intersection T6 on the high-enthalpy side is the evaporation completion temperature. Here, the temperature glide in the evaporator when the working medium is a non-azeotropic mixed medium is shown as the difference between T6 and T4. If the temperature of the working medium vapor A is shown as T7, then T7 - ​​T6 is the degree of superheating (SH) of the working medium in cycles (i) to (iv). Note that T4 represents the temperature of the working medium D.

[0075] The CAP of the working fluid can be calculated using the following formula (11), where hA, hB, hC, and hD are the enthalpy values, hA, hB, hC, and hD of the working fluid in each of the following 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). Assume there are no pressure losses in the piping and heat exchanger.

[0076] When the work lost by the compressor is added to the working fluid as heat, the enthalpy hB' in the working fluid vapor B' after the AB process is expressed by the following equation (10) using the compressor efficiency η, where hA, hB, and η: hB' = hA + (hB - hA) / η ... (10)

[0077] The CAP for evaluating the cycle performance of the working fluid is determined by performing theoretical calculations of the working fluid's heating cycle under the temperature conditions described below, using the National Institute of Science and Technology (NIST) Reference Fluid Thermodynamic and Transport Properties Database (REFPROP 10.0).

[0078] The thermophysical properties of HCFO-1224yd(Z) were obtained using the values ​​described in Akasaka, R. and Lemmon, EW, "A Helmholtz Energy Equation of State for cis-1-Chloro-2,3,3,3-tetrafluoropropene [R-1224yd(Z)]", Int. J. Thermophys., Volume 44, No. 166, (2023). The thermophysical properties of HFO-1234ze(E) were obtained using the values ​​described in Thol, M and Lemmon, EW, "Equation of State for the Thermodynamic Properties of trans-1,3,3,3-Tetrafluoropropene [R-1234ze(E)]", Int. J. Thermophys., Volume 37, No. 1-16, (2016). CAP = (hB - hC) × ρs ... (11) Furthermore, considering the compressor efficiency, CAP becomes the following: CAP = (hB' - hC) × ρs ... (12)

[0079] (Temperature conditions) Examples of temperature conditions include: Superheating degree (SH): 10°C Supercooling degree (SC): 5°C Compressor efficiency η: 0.7 Evaporation temperature: 30°C Condensation temperature: 60°C, 80°C, 100°C, or 120°C Temperature lift: 30°C, 50°C, 70°C, or 90°C

[0080] From the viewpoint of equipment efficiency, the CAP (relative value) of the working medium of this embodiment, calculated under the above temperature conditions and by the method described above, is preferably 1.120 or higher even when the temperature lift is 90°C. When the temperature lift is 90°C, the CAP (relative value) is more preferably 1.125 or higher, and even more preferably 1.130 or higher. When the temperature lift is 70°C, the CAP (relative value) is preferably 1.140 or higher, more preferably 1.150 or higher, and even more preferably 1.160 or higher.

[0081] [Thermal Cycle Method] The thermal cycle method of the present disclosure is a method which involves compressing the vapor of a working medium, cooling and liquefying the vapor of the working medium discharged from the compressor by heat exchange with the fluid to be heated at a condensation temperature of 60°C or higher, reducing the pressure of the liquefied working medium, and heating the reduced-pressure working medium by heat exchange with the fluid to be cooled.

[0082] The working fluid used in the thermal cycling method of this disclosure is the same as the working fluid used in the thermal cycling system of this disclosure.

[0083] The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to the following examples unless it exceeds the spirit of the disclosure. Examples 3 to 13 are examples, and Examples 1, 2, and 14 are comparative examples.

[0084] [Examples 1-14] Working media were prepared by mixing HCFO-1224yd(Z) and HFO-1234ze(E) in the proportions shown in Table 1, and the volume capacity (heating capacity per unit volume CAP) in temperature glide and heating under atmospheric pressure was calculated using the following method.

[0085] <Calculation of Volumetric Capacity (CAP) in Heating> The volumetric capacity (CAP) in heating was calculated by applying a working fluid to the high-temperature heat pump system 10 shown in Figure 1, and performing the thermal cycle shown in Figure 2, namely adiabatic compression by the compressor 11 in the AB process, isobaric cooling by the condenser 12 in the BC process, isenthalpy expansion by the expansion valve 13 in the CD process, and isobaric heating by the evaporator 14 in the DA process. The calculation conditions were as follows: the evaporation temperature of the working fluid in the evaporator 14 (average temperature of the evaporation start temperature and evaporation completion temperature) was 30°C; the condensation completion temperature of the working fluid in the condenser 12 (average temperature of the condensation start temperature and condensation completion temperature) was 60°C, 80°C, 100°C, or 120°C; the degree of subcooling (SC) of the working fluid in the condenser 12 was 5°C; and the degree of superheating (SH) of the working fluid in the evaporator 14 was 10°C. In other words, the temperature lift was set to 30°C, 50°C, 70°C, or 90°C, respectively. Furthermore, the compressor efficiency η was set to 0.7, and it was assumed that there were no pressure losses in the piping and heat exchanger. The above CAP was determined using the enthalpy h of each state of the working medium: A (after evaporation, high 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), from the above formulas (10) and (12) using the method described above. The CAP was then determined as a relative ratio with the CAP of a working medium of HCFO-1224yd(Z) 100 mass% set to 1.00. The results are shown in Table 1 ("CAP (relative value)" in the table).

[0086] <Calculation of Temperature Glide under Atmospheric Pressure> The temperature glide under atmospheric pressure was determined using the method described above. The results are shown in Table 1 ("Temperature Glide" in the table).

[0087]

[0088] As shown in Table 1, in Examples 3 to 13, the CAP is higher than in Examples 1 and 2, and the temperature glide is smaller than in Example 14, indicating a good balance between CAP and temperature glide. In other words, it was confirmed that in Examples 3 to 13, a smaller temperature glide (the temperature difference between the dew point and boiling point of the working fluid under atmospheric pressure) and a higher volume capacity for heating are achieved simultaneously, compared to Examples 1, 2, and 14.

[0089] The disclosure of Japanese Patent Application No. 2024-171518, filed on 30 September 2024, is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if the incorporation of each individual document, patent application, and technical standard were specifically and individually noted.

[0090] 10... Heat pump system 11... Compressor 12... Condenser 13... Expansion valve 14... Evaporator 15, 16... Pump

Claims

1. A thermal cycle working medium comprising (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene, wherein the total content of (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene contained in the thermal cycle working medium is 90.0% by mass or more, and the ratio expressed as (Z)-1-chloro-2,3,3,3-tetrafluoropropene:(E)-1,3,3,3-tetrafluoropropene is 80.5:19.5 to 89.5:10.5 by mass.

2. The thermal cycle working fluid according to claim 1, wherein the ratio represented by (Z)-1-chloro-2,3,3,3-tetrafluoropropene:(E)-1,3,3,3-tetrafluoropropene is 81.0:19.0 to 89.0:11.0 by mass.

3. The thermal cycle working medium according to claim 1, wherein the total content of (Z)-1-chloro-2,3,3,3-tetrafluoropropene and (E)-1,3,3,3-tetrafluoropropene contained in the thermal cycle working medium is 99% by mass or more.

4. A composition for a thermal cycle system comprising a thermal cycle working fluid according to any one of claims 1 to 3.

5. The composition for a thermal cycle system according to claim 4, comprising a lubricating oil.

6. The composition for a thermal cycle system according to claim 4, comprising a stabilizer that suppresses the deterioration of the thermal cycle working medium.

7. A thermal cycle system comprising: a thermal cycle working medium according to any one of claims 1 to 3; a compressor for compressing the thermal cycle working medium; a condenser for exchanging heat between the thermal cycle working medium discharged from the compressor and a fluid to be heated; a depressurizing device for reducing the pressure of the thermal cycle working medium discharged from the condenser; and an evaporator for exchanging heat between the thermal cycle working medium discharged from the depressurizing device and a fluid to be cooled, wherein the condenser is controlled to have a condensation temperature of 60°C or higher.

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