Refrigeration cycle device

Abstract

A refrigeration cycle device provided with a refrigerant circuit (100) including a compressor (3) in which a refrigerant is sealed, the refrigerant including a C1-4 hydrocarbon and a sulfur-based odorant, the compressor (3) being filled with a refrigeration oil including a base oil, and the base oil being filled with a refrigerant containing a sulfur-based odorant. The ratio of the number of oxygen atoms to the number of carbon atoms in the molecular structure of the base oil is less than 0.50.

Description

[0001] This application is a divisional application of a patent application with an application date of August 23, 2022, application number 202280073406.5, and invention name “Refrigeration Cycle Device”. Technical Field

[0002] The present disclosure relates to a refrigeration cycle device. Background Art

[0003] At present, the refrigerant used in the refrigeration cycle device is regulated by, for example, the Freon Emission Control Law (implemented in April 2014). Specifically, the upper limit of the Global Warming Potential (GWP) value of the refrigerant used is set. Therefore, it is necessary to use a refrigerant with a lower GWP.

[0004] In recent years, hydrocarbons (hydrocarbons) with a carbon number of 1 to 4, such as R-290 (propane), R-1270 (propylene), R-600 (butane), and R-600a (isobutane) have been studied as refrigerants with low GWP values. Hydrocarbons with a carbon number of 1 to 4 have a lower GWP value than saturated fluorinated hydrocarbon compounds (hydrofluorocarbons), which are refrigerants with relatively low GWP values.

[0005] However, hydrocarbons having carbon numbers of 1 to 4 have higher flammability than hydrofluorocarbons. For example, in ISO-817, an international standard that specifies the safety level of refrigerants, R-32 (difluoromethane), which is a type of hydrofluorocarbon, is registered as slightly flammable (Class 2L), while R-290, R-1270, R-600, and R-600a are registered as highly flammable (Class 3).

[0006] When a highly flammable refrigerant such as hydrocarbons having a carbon number of 1 to 4 is used as the refrigerant of the refrigeration cycle apparatus, it is preferable to adopt a measure that enables the refrigerant to be identified by smell or sight.

[0007] As a measure that enables the refrigerant to be identified by smell, for example, Patent Document 1 (International Publication No. 2021 / 166028) discloses a method of mixing a sulfur-based odorant with the refrigerant and detecting leakage of the refrigerant using an unpleasant odor.

[0008] Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-38135) discloses that tetrahydrothiophene (THT) is preferred as an odorant because it does not react with the materials of the refrigeration circuit, is compatible with the refrigerant, and is compatible with refrigeration oil.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: International Publication No. 2021 / 166028

[0012] Patent Document 2: Japanese Patent Application Publication No. 2002-38135 Summary of the invention

[0013] Problems to be solved by the invention

[0014] However, the inventors have found that sulfur-based odorants such as THT have polarity due to the bias of charges in the molecule, so when using a high-polarity refrigeration oil, the sulfur-based odorant dissolves in the refrigeration oil in the compressor, and the amount of sulfur-based odorant circulating in the refrigerant circuit together with the refrigerant is reduced, and even when the refrigerant is released from the refrigeration cycle device, it is difficult to detect the refrigerant by smell. In particular, polyalkylene glycol, polyol ester, polyvinyl ether, etc. used as the base oil of refrigeration oil contain a large amount of oxygen (O) as an element with high electronegativity in the molecular structure, and therefore are refrigeration oils with high polarity, and sulfur-based odorants are dissolved in large quantities depending on the composition.

[0015] The present disclosure has been made in view of the above-mentioned problems, and an object of the present disclosure is to provide a refrigeration cycle apparatus that suppresses the dissolution of a sulfur-based odorant in refrigeration oil and enables leakage of a refrigerant to be recognized by smell.

[0016] Means for solving problems

[0017] A refrigeration cycle device according to one aspect of the present disclosure includes a refrigerant circuit including a compressor.

[0018] A refrigerant is sealed in the refrigerant circuit.

[0019] The refrigerant contains hydrocarbons having a carbon number of 1 to 4 and a sulfur-based odorant.

[0020] The compressor is filled with refrigeration oil.

[0021] The refrigeration oil contains a base oil.

[0022] The ratio of the number of oxygen atoms to the number of carbon atoms in the molecular structure of the above-mentioned base oil is less than 0.50.

[0023] A refrigeration cycle device according to another aspect of the present disclosure includes a refrigerant circuit including a compressor.

[0024] A refrigerant is sealed in the refrigerant circuit.

[0025] The refrigerant contains hydrocarbons having a carbon number of 1 to 4 and a sulfur-based odorant.

[0026] The compressor is filled with refrigeration oil.

[0027] The refrigeration oil contains a base oil.

[0028] The difference between the HSP distance between the base oil and the sulfur-based odorant and the HSP distance between the base oil and the hydrocarbon having 1 to 4 carbon atoms is -2.0 or more.

[0029] Effects of the Invention

[0030] According to the present disclosure, it is possible to provide a refrigeration cycle apparatus that suppresses the dissolution of a sulfur-based odorant in refrigeration oil and enables leakage of a refrigerant to be recognized by smell. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic configuration diagram showing an example of the refrigeration cycle apparatus according to the first embodiment.

[0032] Figure 2 It is a schematic cross-sectional view showing an example of a compressor of the refrigeration cycle device according to Embodiment 1.

[0033] Figure 3 It is a graph showing the relationship between the concentration of tetrahydrothiophene in the sealed refrigerant and the concentration of tetrahydrothiophene in the recovered refrigerant gas.

[0034] Figure 4 It is a graph showing the relationship between the concentration of tetrahydrothiophene in the sample gas and the odor index (equivalent value). DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that in the drawings, dimensional relationships such as length, width, thickness, and depth are appropriately changed for the sake of clarity and simplification of the drawings, and do not represent actual dimensional relationships.

[0036] Implementation method 1.

[0037] First, the outline of the refrigeration cycle apparatus according to the present embodiment will be briefly described. Figure 1 1 is a schematic diagram showing an example of a refrigeration cycle device according to Embodiment 1. The outdoor unit 1 includes a compressor 3, a condenser 4, an outdoor fan 5, etc., and the compressor 3 and the condenser 4 are connected by piping. The indoor unit 2 includes an expansion valve 6, an evaporator 7, an indoor fan 8, etc., and the expansion valve 6 and the evaporator 7 are connected by piping.

[0038] The compressor 3 of the outdoor unit 1 and the evaporator 7 of the indoor unit 2 are connected by a gas pipe 10. The condenser 4 of the outdoor unit 1 and the expansion valve 6 of the indoor unit 2 are connected by a liquid pipe 9.

[0039] The refrigerant circuit 100 is formed by the configuration of the refrigeration cycle device as described above, and the refrigerant circulates in the refrigerant circuit 100 via the liquid pipe 9 and the gas pipe 10 .

[0040] The compressor 3 compresses the refrigerant in the gaseous state in the gas pipe 10. The condenser 4 cools the gaseous refrigerant compressed by the compressor 3 to make it a high-pressure liquid refrigerant or a gas-liquid two-phase refrigerant. The expansion valve 6 decompresses the high-pressure liquid refrigerant or the gas-liquid two-phase refrigerant. The evaporator 7 heats the decompressed refrigerant to make it a low-pressure gaseous refrigerant. The compressor 3 sucks the refrigerant in the low-pressure gaseous state through the evaporator 7 and compresses it again.

[0041] It is to be noted that the outdoor blower 5 is a component that delivers air to the condenser 4 and is provided to promote heat absorption or release by heat exchange between the refrigerant flowing into the condenser 4 and the air. In addition, the indoor blower 8 is a component that delivers air to the evaporator 7 and is provided to promote heat absorption or release by heat exchange between the refrigerant flowing into the evaporator 7 and the air.

[0042] In the present embodiment, the configuration for performing heat exchange between the condenser 4 and the evaporator 7 and the air is described, but the present invention is not limited thereto. For example, the configuration may be such that heat exchange is performed with a liquid such as water instead of air.

[0043] In addition, in the present embodiment, the configuration in which the evaporator 7 is provided in the indoor unit 2 is described, but the present invention is not limited thereto. For example, the condenser 4 may be arranged indoors, and the evaporator 7 may be arranged outdoors.

[0044] For the outdoor unit 1 as described above, for example, a switching mechanism for switching the suction pipe and the discharge pipe of the compressor 3 may be provided by combining and configuring a four-way valve or a plurality of valves. By providing the switching mechanism, the heat exchanger in the outdoor unit 1 functions as the evaporator 7, and the heat exchanger in the indoor unit 2 functions as the condenser 4, making it possible to heat the indoor space by utilizing the outdoor heat.

[0045] It should be noted that the refrigeration cycle device may be, for example, a device that can perform both cooling and heating, a device that can only perform cooling, or a device that can only perform heating. In addition, the use of the refrigeration cycle device involved in this embodiment is not limited to air conditioning, and may also be freezing, refrigeration, hot water supply, etc.

[0046] In the present embodiment, the configuration in which the expansion valve 6 is provided in the indoor unit 2 is described, but the present invention is not limited thereto, and for example, the expansion valve 6 may be provided in the outdoor unit 1. In addition, for example, the expansion valve 6 may be provided in both the outdoor unit 1 and the indoor unit 2. Furthermore, for example, a plurality of indoor units 2 may be provided in the refrigerant circuit 100, and a plurality of outdoor units 1 may be provided.

[0047] <Refrigerant>

[0048] Next, in the present embodiment, the refrigerant sealed in the refrigerant circuit will be described. The refrigerant includes a main component that functions as a refrigerant and further includes a sulfur-based odorant for detecting leakage of the refrigerant.

[0049] The so-called "main component" is a component in the refrigerant other than sulfur-based odorants and impurities (air, moisture, byproducts that may be mixed during the synthesis and purification of refrigerant compounds, etc.). The main component of the refrigerant may be a single refrigerant or a mixture of multiple refrigerants. The content of the main component in the refrigerant exceeds 50% by mass, preferably 90% by mass or more, and more preferably 95% by mass or more.

[0050] The main component that functions as a refrigerant is a hydrocarbon with a carbon number of 1 to 4. As hydrocarbons with a carbon number of 1 to 4, for example, R-290 (propane), R-1270 (propylene), R-600 (butane), R-600a (isobutane), etc. can be listed. The hydrocarbon with a carbon number of 1 to 4 is preferably propane, propylene, or a mixture thereof. The reason is that they have a working pressure suitable for use in a refrigeration cycle device. From the viewpoint of oxidation stability, propane is more preferred. As for propane, according to the 6th evaluation report of IPCC, the GWP value is 0.02, which is very low, and it has high cooling performance, so it can contribute to the reduction of the environmental load during the manufacture and operation of the refrigeration cycle device.

[0051] In addition, the refrigerant may further include halogenated hydrocarbons. As halogenated hydrocarbons, for example, chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluoroalkanes, hydrofluoroolefins, hydrochlorofluoroolefins, fluoroiodocarbons, etc. may be cited. Halogenated hydrocarbons have a lower flammability than hydrocarbons by replacing the hydrogen atoms of hydrocarbons with halogen atoms, and by mixing, the flammability of the refrigerant can be reduced. Halogenated hydrocarbons can be filled in a refrigerant circuit in a state mixed with hydrocarbons having a carbon number of 1 to 4, and hydrocarbons having a carbon number of 1 to 4 may also be added to a refrigerant circuit filled with halogenated hydrocarbons or in which halogenated hydrocarbons are rarely left.

[0052] Halogenated hydrocarbon preferably has the same degree of working pressure as hydrocarbon with carbon number of 1 to 4. Thus, the azeotropic property with hydrocarbon with carbon number of 1 to 4 as the main component of refrigerant is improved, and high cooling performance can be obtained. Such halogenated hydrocarbon is halogenated hydrocarbon with carbon number of 1 to 4, more preferably halogenated hydrocarbon with carbon number of 1 to 3. This is because, with regard to halogenated hydrocarbon, compared with hydrocarbon, by halogenating hydrocarbon, molecule becomes larger, and compared with hydrocarbon with the same carbon number, working pressure is reduced. Examples of the halogenated hydrocarbons having 1 to 3 carbon atoms include HFC-23, HFC-32, HFC-41, HFC-125, HFC-134, HFC-134a, HFC-143, HFC-143a, HFC-152, HFC-152a, HFC-161, HFO-1141, HFO-1132a, HFO-1132(E), HFO-1132(Z), HFO-1123, HFO-1132a, HFO-1132(E), HFO-1132(Z), HFO-1124, HFO-1132(E), HFO-1132(Z), HFO-1132(E), HFO-1132(Z), HFO-1132(Z), HFO-1132(Z), HFC ... 225ye(Z), HFO-1225ye(E), HFO-1225zc, HFO-1234yf, HFO-1234ze(E), HFO-1234ze(Z), HFO-1234y e(Z), HFO-1234ye(E), HFO-1243zf, HFO-1252zf, HFO-1261yf, FIC-13I1(CF3I), HCFC-22, CFC-12, etc.

[0053] In addition, the refrigerant may contain carbon dioxide (R-744). As for carbon dioxide, since its GWP is as low as 1, it can contribute to the reduction of the environmental load during the manufacture of the refrigeration cycle device. In addition, since carbon dioxide is non-flammable, the flammability of the refrigerant can be reduced by mixing.

[0054] Note that if air is contained in the refrigerant, it may promote the deterioration of the refrigerant, the sulfur-based odorant, the refrigeration oil described later, the materials in the compressor, etc., so it is preferable to remove the air in the refrigerant circuit before filling the refrigerant circuit with the refrigerant.

[0055] (Sulfur odorant)

[0056] The so-called sulfur-based odorant added to the refrigerant is an odorant containing sulfur element. As the sulfur-based odorant, for example, thiols, sulfides, thiophenes, etc. can be listed. As thiols, for example, methyl mercaptan (MM), ethyl mercaptan (EM), n-propyl mercaptan (NPM), isopropyl mercaptan (IPM), tert-butyl mercaptan (TBM), etc. can be listed, as sulfides, for example, dimethyl sulfide (DMS), diethyl sulfide (DES), methyl ethyl sulfide (MES), etc. can be listed, and as thiophenes, for example, tetrahydrothiophene (THT), etc. can be listed. These sulfur-based odorants are compounds actually used in fuel gas and are compounds with unpleasant odors. These sulfur-based odorants can be used alone or in combination of two or more.

[0057] As the sulfur-based odorant, EM, NPM, IPM, TBM, DMS, MES, THT, or a mixture thereof, which are used in fuel gas for households, are preferred. By mixing the sulfur-based odorant used in fuel gas for households with the refrigerant, leakage of the refrigerant can be easily detected by the unpleasant odor peculiar to the sulfur-based odorant.

[0058] As the sulfur-based odorant, THT is more preferred. THT is chemically stable compared to mercaptans and sulfides, and is less likely to undergo decomposition and corrosion reactions in the refrigerant circuit. In addition, since THT has a low melting point of -96°C, it is less likely to solidify in the refrigerant circuit.

[0059] The content of the sulfur-based odorant is preferably 50 mass ppm or more and less than 1100 mass ppm. This is because, when the content of the sulfur-based odorant is within the above range, leakage of the refrigerant from the refrigerant circuit can be easily detected, and the odor is not excessively unpleasant. The content of the sulfur-based odorant is more preferably 90 mass ppm or more and less than 1026 mass ppm, and further preferably 176 mass ppm or more and less than 987 mass ppm.

[0060] However, due to the long-term operation of the refrigeration cycle device, the sulfur-based odorant may be degraded due to the reaction with the mixed oxygen, etc. For example, in the case of THT, due to oxidative degradation, it changes into oxides such as tetramethylene sulfoxide, and the odor may decrease. Therefore, depending on the use of the refrigeration cycle device, in order to maintain the effect of being able to detect the refrigerant by smell for a long time, it is preferable to set the concentration of the sulfur-based odorant to a slightly higher level.

[0061] The sulfur-based odorant may be any compound that is not used as an odorant in the fuel gas as long as it contains sulfur. For example, hydrogen sulfide, carbonyl sulfide, etc. have a unique unpleasant odor like the above-mentioned sulfur-based odorants, and can easily detect refrigerant leakage.

[0062] In addition, the refrigerant may further include a sulfur-free odorant. This is because, like THT, the sulfur-free odorant is unlikely to cause a corrosive reaction of metals in the refrigerant circuit. Examples of the sulfur-free odorant include cyclohexene, acrylates, ammonia, amines, hydrazines, and norbornenes. In addition to such a sulfur-free odorant, a compound having a unique odor may be further included as an odorant.

[0063] <Compressor>

[0064] In this embodiment, the refrigeration cycle device includes a compressor. A refrigerant passes through the inside of the compressor. The compressor is filled with refrigeration oil. The refrigeration oil contains a base oil.

[0065] Figure 2 2 is a cross-sectional schematic diagram showing an example of a compressor of the refrigeration cycle device involved in this embodiment. Figure 2 As shown in FIG. 1 , a shell 11 is provided. The shell 11 is provided with a compression mechanism 12 inside and a motor 13 for driving the compression mechanism 12. In addition, a suction pipe 14 for allowing the refrigerant to flow into the inside and a discharge pipe 15 for flowing out to the outside are connected to the shell 11. A storage device 16 that separates gas and liquid in the refrigerant and sends the vapor to the suction pipe 14 is connected to the upstream side of the suction pipe 14.

[0066] The refrigerant passing through the accumulator 16 flows from the suction pipe 14 into the compression mechanism 12 in the shell 11. The refrigerant flowing into the compression mechanism 12 is compressed to a high temperature and high pressure, and is discharged from the discharge pipe 15. That is, the compression mechanism 12 is configured to compress the refrigerant flowing from the suction pipe 14 into the shell 11 and discharge it from the discharge pipe 15.

[0067] The compression mechanism 12 is a rotary compression mechanism composed of a combination of a rolling piston 17 and vanes (not shown), etc. The space surrounded by the inner circumference of the barrel chamber 19 of the barrel 18 and the outer circumference of the rolling piston 17 and the vanes (not shown) changes in volume due to the eccentric rotation of the rolling piston 17, thereby compressing the refrigerant.

[0068] The compressed refrigerant is discharged from the discharge hole 21 of the upper bearing 20 to the muffler space 22, and then discharged from the discharge hole 24 of the discharge muffler 23 to the shell 11. The discharged refrigerant passes through the gap of the motor 13 (the gap between the motor rotor 25 and the motor stator 26, the groove provided on the outer peripheral surface of the motor stator 26, etc.), and is discharged from the discharge pipe 15 to the downstream side of the refrigerant circuit 100.

[0069] It should be noted that the compressor 3 has a sliding portion inside the compression mechanism 12. In order to lubricate the sliding portion, refrigeration oil is stored in the oil storage portion 27 located below the compressor 3. The refrigeration oil stored in the oil storage portion 27 is supplied to the sliding portion inside the compression mechanism 12 by a pump action through an oil supply hole (not shown) provided in the shaft of the drive shaft 28. The refrigeration oil contacts the refrigerant in the compressor 3, so a part of the refrigerant is dissolved in the refrigeration oil.

[0070] <Refrigeration oil>

[0071] Next, in this embodiment, the refrigeration oil filled in order to lubricate the compressor is described. The refrigeration oil contains a base oil. The base oil is at least one selected from oxygenated oil and hydrocarbon oil. As oxygenated oil, for example, polyalkylene glycol (PAG), polyol ester (POE), and polyvinyl ether (PVE) can be listed. As hydrocarbon oil, for example, poly α-olefin (PAO), alkylbenzene (AB), alkylnaphthalene (AN), mineral oil, etc. can be listed.

[0072] The base oil is a component that lubricates the compressor by using its kinematic viscosity. The base oil preferably has a kinematic viscosity higher than that of the refrigerant, and more preferably has a kinematic viscosity of 5 mm at 40°C. 2 / s or more and 250mm 2 / s or less. This is because, when the base oil has a higher kinematic viscosity than the refrigerant, the kinematic viscosity of the base oil is sufficient to lubricate the sliding part of the compressor and does not significantly reduce the cooling efficiency of the refrigeration cycle device. It should be noted that the kinematic viscosity of the base oil can be adjusted to be within the above range by changing the molecular structure and polymerization degree of each base oil.

[0073] (Polyalkylene glycol)

[0074] PAG is a polymer represented by the following Chemical Formula 1 and is at least one selected from an ethylene oxide group (EO group) and a propylene oxide group (PO group).

[0075] [Chemistry 1]

[0076]

[0077] In the above chemical formula 1, m and n are respectively a value greater than or equal to 0 representing the average number of EO groups and PO groups, and R 1 and R 2 It is a hydrogen atom (H) or a hydrocarbon chain having a carbon number of 1 or more. The arrangement of the EO group and the PO group may be any of a random copolymer, an alternating copolymer, and a block copolymer.

[0078] In the above chemical formula 1, m and n preferably satisfy the relationship of the following formulas (1) and (2). If the relationship of the following formulas (1) and (2) is not satisfied, PAG may solidify at a low temperature.

[0079] m+n≤100···(1)

[0080] n / (m+n)≥0.20···(2)

[0081] R 1 and R 2 Preferably, it is a hydrocarbon chain having 1 or more carbon atoms. 1 and R 2 In the case of a hydrogen atom (H), the hygroscopicity of PAG increases, and there is a possibility that water may be mixed in.

[0082] In addition, PAG is not limited to PAG having a single structure but may be a mixture of PAGs having different structures. By using a mixture of PAGs having different structures, the properties of the base oil can be adjusted.

[0083] (Polyol Ester)

[0084] POE is an ester synthesized from a polyol and a fatty acid. There are no particular limitations on the method for synthesizing POE, and examples thereof include dehydration condensation of a polyol and a fatty acid.

[0085] The fatty acid is a monovalent or divalent fatty acid. The fatty acid may be an unsaturated fatty acid or a saturated fatty acid. The fatty acid may be a straight-chain fatty acid or a branched-chain fatty acid. The fatty acid is preferably a saturated fatty acid. This is because saturated fatty acids have high oxidation stability, so POE is unlikely to cause thermal degradation. The carbon number of the fatty acid is preferably 4 to 20. This is because, when the carbon number of the fatty acid is 4 to 20, the kinematic viscosity of POE is sufficient to lubricate the sliding part of the compressor and will not significantly reduce the cooling efficiency of the refrigeration cycle device.

[0086] As the monobasic fatty acid with a carbon number of 4 to 20, for example, butyric acid, valeric acid, caproic acid, enanthic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, etc. can be listed. These monobasic fatty acids can include all isomers. These monobasic fatty acids can be straight-chain or branched. More specifically, at least one of the α and β positions can be a branched fatty acid, for example, preferably 2-methylpropionic acid, 2-methylbutyric acid, 2-methylpentanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-methylheptanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, 2-ethylhexadecanoic acid, etc., more preferably 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid. This is because, due to the steric hindrance of the branched chain, the hydrolysis resistance of the ester is excellent.

[0087] Examples of the divalent fatty acid having 4 to 20 carbon atoms include glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0088] The fatty acid may contain fatty acids other than fatty acids having carbon numbers of 4 to 20. As fatty acids other than fatty acids having carbon numbers of 4 to 20, for example, fatty acids having carbon numbers of 21 to 24 can be cited, and specifically, heneicosanoic acid, docosanoic acid, tricosanoic acid, tetracosanoic acid, etc. can be cited. These fatty acids may be linear or branched.

[0089] The fatty acid constituting POE may be any one of the above-mentioned ones, or may contain two or more kinds.

[0090] The polyol is preferably a polyol having 2 to 6 hydroxyl groups. This is because, in the case of a polyol having 2 to 6 hydroxyl groups, the kinematic viscosity of POE is sufficient to lubricate the sliding portion of the compressor and will not significantly reduce the cooling efficiency of the refrigeration cycle device. As the carbon number of the polyol, preferably 4 to 12, more preferably 5 to 10. As such a polyol, for example, preferably neopentyl glycol, trimethylolethane, trimethylolpropane, trimethylolbutane, di-(trimethylolpropane), tri-(trimethylolpropane), pentaerythritol, dipentaerythritol and other hindered alcohols.

[0091] The polyol constituting POE may be any one of the above-mentioned ones, or may contain two or more kinds.

[0092] POE may be a partial ester in which a part of the hydroxyl groups of the polyol are not esterified and the hydroxyl groups remain, a complete ester in which all the hydroxyl groups are esterified, or a mixture of a partial ester and a complete ester.

[0093] When the fatty acid is a dibasic fatty acid, both carboxyl groups may be esterified, or only one carboxyl group may be esterified. When both carboxyl groups of the dibasic fatty acid are esterified, one carboxyl group may be an ester with a monohydric alcohol instead of a polyhydric alcohol. The monohydric alcohol preferably has 1 to 20 carbon atoms.

[0094] In addition, POE may be not only POE having a single structure but also a mixture of POEs having different structures. By using a mixture of POEs having different structures, the properties of the base oil can be adjusted.

[0095] (Polyvinyl ether)

[0096] PVE is a compound obtained by a polymerization reaction of a vinyl ether compound, and has a polyvinyl ether structure represented by the following Chemical Formula 2.

[0097] [Chemistry 2]

[0098]

[0099] In the above chemical formula 2, R 1 , R 2 and R 3 Each represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, and they may be the same as or different from each other. 4 is a hydrocarbon group having 2 to 10 carbon atoms, R 5 is a hydrocarbon group having 1 to 10 carbon atoms, and k represents R 4 The average value of the number of O is greater than or equal to 0 and less than or equal to 10. 1 To R 5 Each structural unit may be the same or different from each other. 4 When there are multiple O, multiple R 4 O may be the same or different. n is a numerical value of 2 or more representing the average number of structural units of the polyvinyl ether structure.

[0100] As R 1 , R 2 and R 3 For example, there can be mentioned a hydrogen atom (H), a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, various pentyl groups, various hexyl groups, various heptyl groups, various octyl groups and other alkyl groups, a cyclopentyl group, a cyclohexyl group, various methylcyclohexyl groups, various ethylcyclohexyl groups, various dimethylcyclohexyl groups and other cycloalkyl groups, a phenyl group, various methylphenyl groups, various ethylphenyl groups, various dimethylphenyl groups and other aryl groups, a benzyl group, various phenylethyl groups, various methylbenzyl groups and other arylalkyl groups, and the like. These R 1 , R 2 and R 3 Among them, a hydrogen atom (H) or a hydrocarbon group having 1 to 5 carbon atoms is preferred, and a hydrogen atom (H) or a hydrocarbon group having 1 to 3 carbon atoms is more preferred.

[0101] As R 4 Examples thereof include hydrocarbon groups such as ethylene, phenylethylene, 1,2-propylene, 2-phenyl-1,2-propylene, 1,3-propylene, various butylene groups, various pentylene groups, various hexylene groups, various heptylene groups, various octylene groups, various nonylene groups, and various decylene groups; alicyclic groups having two bonding sites in alicyclic hydrocarbons such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, and propylcyclohexane; aromatic hydrocarbon groups such as various phenylene groups, various methylphenylene groups, various ethylphenylene groups, various dimethylphenylene groups, and various naphthalene groups; alkyl aromatic groups having monovalent bonding sites in the alkyl part and aromatic part of alkyl aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; and alkyl aromatic groups having bonding sites in the alkyl part of polyalkyl aromatic hydrocarbons such as xylene and diethylbenzene. These R 4 Among them, an alkyl group having a carbon number of 2 to 4 is preferred. In addition, k is preferably a numerical value of 0 or more and 5 or less.

[0102] As R 5 , alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, various pentyls, various hexyls, various heptyls, various octyls, various nonyls, and various decyls, cycloalkyl groups such as cyclopentyl, cyclohexyl, various methylcyclohexyls, various ethylcyclohexyls, various propylcyclohexyls, and various dimethylcyclohexyls, aryl groups such as phenyl, various methylphenyls, various ethylphenyls, various dimethylphenyls, various propylphenyls, various trimethylphenyls, various butylphenyls, and various naphthyls, arylalkyl groups such as benzyl, various phenylethyls, various methylbenzyls, various phenylpropyls, and various phenylbutyls can be listed. These R 5 In the above, a hydrocarbon group having a carbon number of 8 or less is preferred. In addition, when k is 0, an alkyl group having a carbon number of 1 to 6 is more preferred, and when k is 1 or more, an alkyl group having a carbon number of 1 to 4 is more preferred.

[0103] In addition, PVE may be not only PVE having a single structure but also a mixture of PVE having different structures. By using a mixture of PVE having different structures, the properties of the base oil can be adjusted.

[0104] (Poly alpha olefin)

[0105] As PAO, for example, products obtained by polymerizing hydrocarbon monomers having olefinic double bonds can be cited. As hydrocarbon monomers having olefinic double bonds, for example, ethylene, propylene, various butenes, various pentenes, various hexenes, various heptenes, various octenes, diisobutylene, triisobutylene, styrene, α-methylstyrene, various alkyl-substituted styrenes, etc. can be cited. The hydrocarbon monomers having olefinic double bonds can be used alone or in combination of two or more.

[0106] In addition, PAO is not limited to PAO having a single structure but may be a mixture of PAOs having different structures. By using a mixture of PAOs having different structures, the properties of the base oil can be adjusted.

[0107] (Alkylbenzene)

[0108] AB is a compound in which at least one of the hydrogen atoms of benzene is replaced by a hydrocarbon group. As AB, a product in which 1 to 4 of the hydrogen atoms are replaced by hydrocarbon groups is preferred, and a product in which 1 to 2 of the hydrogen atoms are replaced by hydrocarbon groups is more preferred. This is because stability and availability are excellent. As the hydrocarbon group, a hydrocarbon group with a carbon number of 1 to 19 is preferred. This is because, in the case of a hydrocarbon group with a carbon number of 1 to 19, the kinematic viscosity of AB is sufficient to lubricate the sliding part of the compressor and does not significantly reduce the cooling efficiency of the refrigeration cycle device.

[0109] Examples of hydrocarbon groups having 1 to 19 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl. These hydrocarbon groups may include all isomers. These hydrocarbon groups may be straight-chain or branched.

[0110] In addition, AB is not limited to AB having a single structure but may be a mixture of ABs having different structures. By using a mixture of ABs having different structures, the properties of the base oil can be adjusted.

[0111] (Alkylated naphthalene)

[0112] AN is a compound in which at least one of the hydrogen atoms (H) of naphthalene is replaced by a hydrocarbon group. As AN, a product in which 1 to 4 of the hydrogen atoms (H) are replaced by hydrocarbon groups is preferred, and a product in which 1 to 3 of the hydrogen atoms (H) are replaced by hydrocarbon groups is more preferred. This is because stability and availability are excellent. The hydrocarbon group is preferably a hydrocarbon group with a carbon number of 1 to 19. This is because, in the case of a hydrocarbon group with a carbon number of 1 to 19, the kinematic viscosity of AN is sufficient to lubricate the sliding part of the compressor and does not significantly reduce the cooling efficiency of the refrigeration cycle device.

[0113] Examples of hydrocarbon groups having 1 to 19 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and eicosyl. These hydrocarbon groups may include all isomers. These hydrocarbon groups may be straight-chain or branched.

[0114] In addition, AN may be not only AN having a single structure but also a mixture of AN having different structures. By using a mixture of AN having different structures, the properties of the base oil can be adjusted.

[0115] (Mineral Oil)

[0116] Mineral oil is a lubricating oil obtained by separation and purification of crude oil. Mineral oil includes paraffinic mineral oil and naphthenic mineral oil, and any one of them may be used or a mixture thereof may be used.

[0117] (Additives in oil)

[0118] Furthermore, the refrigerating machine oil may contain an antioxidant, an acid trapping agent, and an extreme pressure agent (anti-wear agent) as an oil additive.

[0119] As antioxidants, phenols such as 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol) and amines such as phenyl-α-naphthylamine and N,N'-di-phenyl-p-phenylenediamine can be cited. Antioxidants have the effect of suppressing not only the deterioration of refrigeration oil but also the oxidative deterioration of sulfur-based odorants.

[0120] The content of the antioxidant relative to the refrigeration oil is preferably 0.05% by mass or more and 2% by mass or less, and more preferably 0.2% by mass or more and 1% by mass or less. When the content of the antioxidant relative to the refrigeration oil is less than 0.05% by mass, the effect of the antioxidant may not be obtained. When the content of the antioxidant relative to the refrigeration oil exceeds 2% by mass, the kinematic viscosity of the refrigeration oil may be reduced, or the refrigeration oil may be blocked as an inclusion due to deterioration.

[0121] Examples of the acid capture agent include phenyl glycidyl ether, alkyl glycidyl ester, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, epoxidized soybean oil and other epoxy compounds. As the acid capture agent, alkyl glycidyl ester, alkyl glycidyl ether, and α-olefin oxide are preferred. The acid capture agent captures the acid generated by the deterioration of organic materials (insulating film, sealing material, etc.) present in the refrigerator oil and the refrigerant circuit, and thus has the effect of suppressing the deterioration of the sulfur-based odorant caused by the acid.

[0122] The content of the acid capture agent relative to the refrigeration oil is preferably 0.05% by mass or more and 10% by mass or less, and more preferably 0.1% by mass or more and 10% by mass or less. If the content of the acid capture agent relative to the refrigeration oil is less than 0.05% by mass, the effect of the acid capture agent may not be obtained. If the content of the acid capture agent relative to the refrigeration oil exceeds 10% by mass, the kinematic viscosity of the refrigeration oil may decrease, or the refrigeration oil may become an inclusion and block the refrigerant circuit due to deterioration.

[0123] As extreme pressure agents (anti-wear agents), phosphorus-based extreme pressure agents such as phosphates, thiophosphates, acidic phosphates, phosphites, acidic phosphites and their amine salts can be cited. As extreme pressure agents (anti-wear agents), phosphates, thiophosphates or mixtures thereof are preferred. Specifically, tricresyl phosphate (O=P-(OC7H7)3), triphenyl thiophosphate (S=P-(OC6H5)3), triphenyl phosphate (O=P-(OC6H5)3), their derivatives or mixtures thereof are preferred. The extreme pressure agent reduces the friction of the sliding part of the compressor, and therefore has the effect of suppressing the deterioration of the sulfur-based odorizer caused by frictional heat.

[0124] The content of the extreme pressure agent relative to the refrigeration oil is preferably 0.05% by mass or more and 5% by mass or less, and more preferably 0.1% by mass or more and 4% by mass or less. When the content of the extreme pressure agent relative to the refrigeration oil is less than 0.05% by mass, the effect of the extreme pressure agent may not be obtained. When the content of the extreme pressure agent relative to the refrigeration oil exceeds 5% by mass, the extreme pressure agent may cause metal corrosion, or the kinematic viscosity of the refrigeration oil may be reduced, or the refrigerant circuit may be blocked as an inclusion due to deterioration.

[0125] In addition, an oxygen capture agent may be included in the refrigerating machine oil. As the oxygen capture agent, for example, sulfur-containing aromatic compounds such as 4,4'-thiobis(3-methyl-6-tert-butylphenol), diphenyl sulfide, dioctyl diphenyl sulfide, dialkyl diphenylene sulfide, benzothiophene, dibenzothiophene, phenothiazine, benzothiapyran, thiapyran, thianthrene, dibenzothiapyran, diphenylene disulfide, various olefins, aliphatic unsaturated compounds such as dienes and trienes, cyclic terpenes with unsaturated bonds such as α-pinene, β-pinene, limonene, and phellandrene can be listed. As the oxygen capture agent, aliphatic unsaturated compounds, cyclic terpenes with unsaturated bonds, etc. are preferred. The oxygen capture agent has the effect of inhibiting not only the oxidative degradation of the refrigerating machine oil but also the oxidative degradation of the sulfur-based odorant.

[0126] The content of the oxygen capture agent relative to the refrigeration oil is preferably 0.05 mass % or more and 5 mass % or less, and more preferably 0.1 mass % or more and 3 mass % or less. If the content of the oxygen capture agent relative to the refrigeration oil is less than 0.05 mass %, the effect of the oxygen capture agent may not be obtained. If the content of the oxygen capture agent relative to the refrigeration oil exceeds 5 mass %, the kinematic viscosity of the refrigeration oil may decrease, or the refrigeration oil may become an inclusion and block the refrigerant circuit due to deterioration.

[0127] (other)

[0128] Refrigerator oil may contain a fluorescent agent, a colorant, etc., in order to visually detect the refrigerant and the refrigeration oil. The fluorescent agent and the colorant are preferably added in an amount not exceeding the saturated solubility amount of the refrigeration oil so that precipitation does not occur at low temperatures.

[0129] It should be noted that if the refrigeration oil contains water, it may promote the deterioration of the refrigerant, refrigeration oil, metals in the refrigeration circuit, organic materials (polyester, etc.) in the refrigeration circuit, etc. Therefore, the water content in the filled refrigeration oil needs to be controlled below 300 mass ppm, preferably below 100 mass ppm.

[0130] In the above-mentioned refrigeration cycle device, the form of using a rotary compressor as the compressor 3 is described, but it is not limited to this. For example, as the compressor 3, a scroll compressor or a screw compressor of a low-pressure shell type (シェル type) or a high-pressure shell type (シェル type) can be used.

[0131] (Ratio of oxygen atoms to carbon atoms in the molecular structure of the base oil)

[0132] The ratio of the number of oxygen atoms (O) to the number of carbon atoms (C) in the molecular structure of the base oil (O / C ratio) (hereinafter also referred to as "O / C ratio") is less than 0.50. When the O / C ratio is less than 0.50, the polarity generated by polarization becomes smaller, the intermolecular interaction between the base oil and the sulfur-based odorant becomes smaller, the amount of sulfur-based odorant dissolved in the base oil becomes smaller, and the refrigerant released from the refrigerant circuit can be identified by smell. The O / C ratio is preferably less than 0.43, and more preferably less than 0.39. In addition, there is no particular restriction on the lower limit of the O / C ratio, and it can be 0 like hydrocarbon oil.

[0133] In refrigeration oil, if the O / C ratio in the molecular structure of the base oil is smaller than that of PAG, other refrigeration oils may be mixed. As other refrigeration oils, for example, polyol esters, polyvinyl ethers, alkylbenzenes, alkylnaphthalenes, mineral oils, poly-α-olefins, or mixtures thereof may be cited. As for polyol esters and polyvinyl ethers, similar to PAG, they have low compatibility with hydrocarbons having 1 to 4 carbon atoms, and therefore are preferred from the perspective of small amount of refrigerant dissolved and ability to reduce the amount of refrigerant charged.

[0134] If the O / C ratio is less than 0.50, the base oil may not have a single structure but may be a mixture of base oils with different structures. The O / C ratio of the mixture is calculated by taking the weighted average of the O / C ratios from the molar ratios of the base oils relative to the entire base oil. For example, when POE (complete esterification of pentaerythritol and 2-ethylhexanoic acid) with an O / C ratio of 8 / 37 and PVE (in the above chemical formula 2, R 1 , R 2 and R 3 is a hydrogen atom (H), k is 0, R 5 In the case of a base oil in which a polymer (in which N is ethyl and n is 10) is mixed at a molar ratio of 1:1, the O / C ratio becomes 8 / 37×0.5+1 / 4×0.5=69 / 236.

[0135] The sulfur-based odorant contained in the refrigerant is a polar molecule having a dipole moment generated by the bias of the charge in the molecule. For example, according to the document (J.Am.Chem.Soc., Vol. 61, pp. 1769-1780, 1939), the dipole moment of THT is 1.87D. Since the dipole moments of H2O and CH3OH, which are polar solvents, are 1.9D and 1.7D, respectively, THT is a polar molecule with a large dipole moment. In addition, according to the document (J.Chem.Phys., Vol. 1, pp. 337-340, 1933), it is reported that the dipole moment of thiols is about 1.3D to 1.5D, and the dipole moment of sulfides is about 1.4D to 1.58D, which are polar molecules like THT.

[0136] As described above, the sulfur-based odorant is a polar molecule, and therefore dissolves in the base oil through electrical interaction with the polar groups (parts having bonds between C and O) of the base oil. In the case of a base oil with a large O / C ratio, since there are many polar groups in the molecular structure, a strong electrical interaction with the sulfur-based odorant occurs. Therefore, when a base oil with a large O / C ratio is mixed with a sulfur-based odorant, it is difficult to release the sulfur-based odorant.

[0137] As for the main component that functions as a refrigerant, that is, hydrocarbons with 1 to 4 carbon atoms, since there is no polar group in the molecule, it is a non-polar molecule with a very small charge bias. For example, according to the document (J. Chem. Phys., Vol. 33, No. 5, pp. 1519-1522, 1960), the dipole moment of R-290 is a small value of 0.083D, which is a non-polar molecule. In addition, according to the document (J. Chem. Phys., Vol. 27, No. 4, pp. 868-873, 1957), the dipole moment of R-1270 is 0.364D, and according to another document (J. Chem. Phys., Vol. 29, No. 4, pp. 914-920, 1958), the dipole moment of R-600a is 0.132D. Therefore, hydrocarbons having 1 to 4 carbon atoms do not have a polar group in the molecule and are therefore non-polar molecules with very small charge bias.

[0138] As described above, since hydrocarbons with a carbon number of 1 to 4 are non-polar molecules, the solubility of sulfur-based odorants in hydrocarbons with a carbon number of 1 to 4 is low. If hydrocarbons with a carbon number of 1 to 4 are dissolved in the base oil, the solubility of the sulfur-based odorant in the base oil decreases. The larger the O / C ratio of the base oil, the more polar groups it has in its molecular structure, so the solubility of hydrocarbons with a carbon number of 1 to 4, which are non-polar molecules, is low. The smaller the O / C ratio of the base oil, the greater the solubility of hydrocarbons with a carbon number of 1 to 4, so a large amount of hydrocarbons with a carbon number of 1 to 4 are dissolved in the base oil. Therefore, the solubility of the sulfur-based odorant in the base oil becomes lower, making it easier for the sulfur-based odorant to be released.

[0139] For example, even if the base oil has an O / C ratio of 0.50 or more, if the weighted average O / C ratio is less than 0.50 due to mixing with other base oils, the polarity of the base oil as a whole decreases, the amount of sulfur-based odorant dissolved decreases, and the refrigerant released from the refrigerant circuit can be identified by smell.

[0140] <HSP distance>

[0141] The difference between the HSP distance between the base oil and the sulfur-based odorant and the HSP distance between the base oil and hydrocarbons having 1 to 4 carbon atoms ([HSP distance between the base oil and the sulfur-based odorant] - [HSP distance between the base oil and hydrocarbons having 1 to 4 carbon atoms]) is -2.0 or more. In the following, the HSP distance between the base oil and the sulfur-based odorant may be referred to as "HSP distance with the sulfur-based odorant", and the HSP distance between the base oil and hydrocarbons having 1 to 4 carbon atoms may be referred to as "HSP distance with hydrocarbons".

[0142] Among them, "HSP" stands for "Hansen Solubility Parameter", which is a value used to predict the solubility between substances based on the idea that "substances with similar intermolecular interactions tend to dissolve each other". Specifically, HSP is expressed as a three-dimensional vector using three parameters (dD, dP, dH), which are dispersion term, polarization term, and hydrogen bond term. For two substances, the more similar the vectors (dD, dP, dH) are, the greater the solubility.

[0143] The HSP of a substance can be obtained by quoting from a database or calculating from a molecular structure using HSPiP (Hansen Solubility Parameter in Practice) Ver. 5.3, which is computer software.

[0144] In addition, "HSP distance" is the distance between the HSP values ​​of two substances, and is a value representing the similarity between the vectors ((dD1, dP1, dH1) and (dD2, dP2, dH2)) of the two substances. Specifically, based on the above three parameters (dD, dP, dH), it is calculated using the following formula (3). It should be noted that in the following formula (3), for the two substances whose HSP distance is calculated, the dD, dP and dH of one substance are set to dD1, dP1 and dH1, and the dD, dP and dH of the other substance are set to dD2, dP2 and dH2. For two substances, the larger the HSP distance, the smaller the solubility.

[0145] HSP distance = {4 × (dD1-dD2) 2 +(dP1-dP2) 2 +(dH1-dH2) 2} 0.5

[0146] ···(3)

[0147] The smaller the amount of sulfur-based odorant dissolved in the base oil, the greater the amount of sulfur-based odorant circulating in the refrigerant circuit, and the refrigerant discharged from the refrigerant circuit can be identified by smell. In addition, the greater the amount of hydrocarbons having a carbon number of 1 to 4 dissolved in the base oil, the smaller the amount of sulfur-based odorant dissolved in the base oil for the reasons described below, and as a result, the greater the amount of sulfur-based odorant circulating in the refrigerant circuit, and the refrigerant discharged from the refrigerant circuit can be identified by smell. That is, the greater the difference between the HSP distance to the sulfur-based odorant and the HSP distance to the hydrocarbon ([HSP distance to the sulfur-based odorant] - [HSP distance to the hydrocarbon]), the smaller the amount of sulfur-based odorant dissolved in the base oil, and the refrigerant discharged from the refrigerant circuit contains a large amount of sulfur-based odorant, which can be identified by smell.

[0148] When the difference between the HSP distance to the sulfur-based odorant and the HSP distance to hydrocarbons is -2.0 or more, the amount of the sulfur-based odorant dissolved in the base oil is small enough to identify the refrigerant released from the refrigerant circuit by smell. The difference between the HSP distance to the sulfur-based odorant and the HSP distance to hydrocarbons is preferably -0.5 or more, more preferably -0.4 or more. In addition, the upper limit of the difference between the HSP distance to the sulfur-based odorant and the HSP distance to hydrocarbons is not particularly limited, and may be 10 or less, or 5.0 or less.

[0149] Example

[0150] Hereinafter, the present disclosure will be described in detail with reference to Examples, but the present disclosure is not limited to these Examples.

[0151] <Evaluation Test 1>

[0152] In order to evaluate the amount of sulfur-based odorant released together with the refrigerant when the refrigerant, sulfur-based odorant and refrigeration oil are mixed, a refrigerant gas obtained by mixing the refrigerant, sulfur-based odorant and refrigeration oil was prepared under the conditions shown in Table 1. As the refrigeration oil, a refrigeration oil using PAG as a base oil was used. Regarding the base oil, m in the above chemical formula 1 is 7 (rounded to the first decimal place), n is 36 (rounded to the first decimal place), R 1 and R 2 In addition, Table 2 shows the concentration of the sulfur-based odorant (THT) in the refrigerant gas.

[0153] [Table 1]

[0154]

[0155] [Table 2]

[0156]

[0157] The refrigerant gas was sealed in a test container, stirred by vibration at 140° C., and then left to stand at 25° C. After 24 hours from the start of the standing, a teraphone bag (1-2711-05 manufactured by Aswan Co., Ltd.) was connected to the discharge port of the test container to recover the refrigerant gas at 25° C. The recovered refrigerant gas was measured for THT concentration using a gas chromatograph mass spectrometer (JMS-K9 manufactured by JEOL Ltd.).

[0158] The relationship between the concentration of THT in the sealed refrigerant gas and the concentration of THT in the recovered refrigerant gas is shown in FIG. Figure 3 As for the concentration of THT in the recovered refrigerant gas, the concentration of THT in the sealed refrigerant gas increases in a linear relationship from 2.3 mass ppm to 987 mass ppm, and increases in a linear relationship with a larger slope from 987 mass ppm to 2230 mass ppm. Figure 3 In terms of the mathematical formula of the approximate line in , y=0.047x is obtained when the concentration of THT is in the range of 2.3 mass ppm to 987 mass ppm, and y=1.66x-774 is obtained when the concentration of THT in the sealed refrigerant gas is in the range of 2.3 mass ppm to 987 mass ppm. That is, in the range of 2.3 mass ppm to 987 mass ppm, the amount of THT released together with R-290 is about 4.7% of the sealed THT, and the remaining about 95.3% is still dissolved in PAG and is not released as gas.

[0159] Even if THT is mixed in R-290 as described above, PAG dissolves THT, so only a part of THT in the sealed refrigerant gas is released together with R-290. It has been confirmed that it is difficult to detect the refrigerant by smell even when the refrigerant is released from the refrigeration cycle device.

[0160] <Evaluation Test 2>

[0161] In order to quantitatively evaluate the relationship between the concentration of the sulfur-based odorant in the air and the intensity of the odor, a sample gas in which air and a sulfur-based odorant (THT) were mixed was prepared under the conditions shown in Table 3. Table 4 also shows the concentration of THT in the sample gas.

[0162] [Table 3]

[0163]

[0164] [Table 4]

[0165]

[0166] For the above sample gas, the odor index (equivalent value) is measured. The so-called "odor index" refers to an index that quantifies the degree of odor using human sense of smell, and is a value obtained by multiplying the common logarithm of the odor concentration of the odor component (the concentration of the odor component when diluted with air until the odor is no longer felt by human sense of smell) by 10. In addition, the so-called "odor index (equivalent value)" is a numerical value equivalent to the odor index obtained in the measurement using an odor recognition device. The measurement uses nitrogen (N2) as a carrier gas, and the dilution ratio of the sample using the carrier gas is set to 100 times.

[0167] The relationship between the concentration of THT in the sample gas and the odor index (equivalent value) is shown in Figure 4 . The relationship between the concentration of THT in the sample gas and the odor index (equivalent value) is a logarithmic function. This means that the result of the Weber-Fechner law, which represents the relationship between the concentration of odorous substances and the intensity of odor, was obtained. It should be noted that in this test, high-purity air was used as the gas for diluting THT, and when THT was diluted with R-290, since R-290 is odorless, it is considered that the same correlation as that between the concentration of THT and the odor index (equivalent value) was obtained.

[0168] In addition, the odor index has a relationship with the odor intensity in the 6-level odor intensity representation method as shown in Table 5. The concentration of THT shown in Table 5 is Figure 4 The relationship between the THT concentration and the odor index (equivalent value) was calculated, and the THT concentration corresponding to the odor intensity of 2.5 to 3.5 was obtained.

[0169] [Table 5]

[0170]

[0171] In order to identify the refrigerant by smell, it is necessary to identify the presence of the sulfur-based odorant contained in the refrigerant. That is, the odor intensity of the refrigerant is preferably 2 (a weak odor that is known to have a certain odor) or more, and more preferably 3 (an odor that can be easily perceived) or more.

[0172] The refrigerant released from the refrigerant circuit to the atmosphere is diluted by air, and the concentration of THT decreases. In the international standard ISO-13734 related to the odorization treatment of natural gas, it is stated that natural gas must have an odor even when diluted to 20% by volume of its LFL (Lower Flammability Limit). In ISO-817, it is stated that the LFL of R-290 is 21000 volume ppm, so 20% of the LFL is 4200 volume ppm.

[0173] In addition, the Japanese government order related to gas odorization (government order stipulating technical standards for gas working materials (Order of the Ministry of International Trade and Industry No. 111 of 1998)) states that for gas odorization, it is necessary to "be able to detect the presence or absence of odor when the mixed volume ratio of gas in air is one thousandth". That is, when the concentration of R-290 is diluted to 1000 volume ppm in the air, R-290 needs to be able to be identified by odor, requiring odorization stronger than ISO-13734.

[0174] In a mixed gas of air and THT containing 1000 ppm of R-290, in order to make the odor intensity of the mixed gas to be above 2, THT needs to be contained at a concentration of 2.1 volume ppb or more. In other words, the mixed gas of R-290 and THT needs to contain 2.1 volume ppm (4.2 mass ppm) or more of THT.

[0175] In order to make the odor intensity of the mixed gas 3 or more, THT needs to be contained at a concentration of 4.1 volume ppb or more. In other words, the mixed gas of R-290 and THT needs to contain 4.1 volume ppm (8.2 mass ppm) or more of THT.

[0176] As described above, by quantitatively clarifying the relationship between the concentration of THT in the sample gas and the intensity of the odor, the concentration of THT required for identifying the refrigerant by smell is confirmed.

[0177] exist Figure 3 In the results of the evaluation test 1 shown, the concentrations of THT in the released refrigerant gas were 90 mass ppm and 176 mass ppm, respectively, when the THT concentration in the released refrigerant gas was 4.2 mass ppm and 8.2 mass ppm. That is, when the PAG used in the evaluation test 1 is used in a refrigeration cycle device, if the THT concentration in the refrigerant is 90 mass ppm or more, even if the refrigerant gas released from the refrigerant circuit is diluted to 1 / 1000 times in the air, it can be recognized by smell.

[0178] On the other hand, if the odor intensity of the air containing the refrigerant gas reaches 5 (strong odor), the odor of the released refrigerant gas is excessively unpleasant. Figure 3 In the results of the evaluation test 1 shown in , the concentration of THT in the discharged refrigerant is 77 volume ppm (154 mass ppm), and the concentration of THT is 514 volume ppm (1026 mass ppm). That is, when the PAG shown in Table 2 is used in a refrigeration cycle device, if the THT concentration in the refrigerant is less than 1026 mass ppm, the refrigerant gas discharged from the refrigerant circuit will not become an excessively unpleasant odor when diluted to 1 / 1000 times in the air.

[0179] However, long-term operation of the refrigeration cycle device may cause degradation due to the reaction between THT and mixed oxygen, etc. Therefore, it is preferred that the concentration of THT is set high according to the use of the refrigeration cycle device so that the effect of long-term olfactory detection of the refrigerant can be sustained.

[0180] Note that the concentration of the sulfur-based odorant and the odor index have a correlation according to the Weber-Fechner law, which is not limited to THT. Therefore, the above method can determine the concentration that produces a sufficient odor for any sulfur-based odorant.

[0181] <Evaluation Test 3>

[0182] In order to confirm the influence of the molecular structure of the refrigeration oil on the results of the evaluation test 1, a refrigerant gas was prepared by mixing R-290 containing a sulfur-based odorant (THT) as a refrigerant with a refrigeration oil having a PAG as a base oil as shown in Table 6 under the conditions shown in Table 7. The concentration of THT in the refrigerant was set to 600 mass ppm so that the odor intensity of the refrigerant described in Table 5 would be 3.

[0183] [Table 6]

[0184]

[0185] [Table 7]

[0186]

[0187] The molecular structures of PAGs shown in Table 6 are values ​​determined based on the number average degree of polymerization of the compositions of the respective PAGs, and m and n are values ​​rounded off to the first decimal place. In addition, the O / C ratio is a value represented by rounding off the third digit from the ratio of the number of oxygen atoms (O) to the number of carbon atoms (C) in the molecular structure to two significant figures.

[0188] The above-mentioned refrigerant gas was sealed in a test container, stirred by vibration at 140°C, and then allowed to stand at 25°C. After 24 hours from the start of the standing, a tedala bag (1-2711-05 manufactured by Azwan Co., Ltd.) was connected to the discharge port of the test container to recover the refrigerant gas at 25°C. The recovered refrigerant gas was diluted to 1 / 1000 times using high-purity air (ZER0-A manufactured by Sumitomo Seika Co., Ltd.), and the odor intensity was evaluated by the odor sensory test method with reference to the literature (Journal of the Atmospheric Pollution Society, Vol. 27, No. 2, P.A17-A24, 1992). The results of the odor intensity of the recovered refrigerant gas expressed by the 6-level odor intensity representation method are shown in Table 8. The evaluation was conducted by five testers, with odor intensity of 2 or more being designated as "A" and odor intensity of 1 or less being designated as "B".

[0189] [Table 8]

[0190] PAG No. O / C Ratio Odor intensity evaluate 1 0.58 0～1 B 2 0.53 0～1 B 3 0.43 2～3 A 4 0.43 2～3 A 5 0.43 3～4 A 6 0.42 3～4 A 7 0.39 3～4 A 8 0.39 3～4 A 9 0.36 3～4 A 10 0.35 3～4 A 11 0.35 3～4 A 12 0.35 2～3 A 13 0.33 3～4 A

[0191] As for the results of the above evaluation, for the refrigerant gas mixed with PAG (No. 3-13) having an O / C ratio of less than 0.50, as described above, the amount of THT dissolved in PAG became sufficiently small, and the odor intensity ranged from 2 (a weak odor that was known to have a certain odor) to 4 (a strong odor), and it was confirmed that THT was contained in the refrigerant gas. On the other hand, for the refrigerant gas mixed with PAG (No. 1 and 2) having an O / C ratio of more than 0.50, the odor intensity ranged from 0 (odorless) to 1 (an odor that was barely perceptible), and it was not confirmed that THT was contained in the refrigerant gas.

[0192] This result means that the amount of THT dissolved in PAG and not released together with the refrigerant gas can be explained by the ratio of polar groups (sites having bonds of C and O) in the molecular structure of PAG.

[0193] As described above, THT is a polar molecule with a dipole moment of 1.87D, so it is absorbed by the molecular chain of PAG and dissolved through electrical interaction with the polar groups (parts with bonds between C and O) of PAG. For PAG with a large O / C ratio, since there are a large number of polar groups in the molecular structure, the strong electrical interaction of THT is exerted. Therefore, when PAG with a large O / C ratio is mixed with THT, it is difficult to release THT.

[0194] In addition, as mentioned above, R-290 is a non-polar molecule with a dipole moment of 0.083D, so the solubility of THT in R-290 is low. If R-290 is dissolved in PAG, the solubility of THT in PAG decreases. For PAG with a large O / C ratio, since it has a large number of polar groups in its molecular structure, the solubility of R-290 as a non-polar molecule is low. For PAG with a small O / C ratio, since R-290 has a high solubility, more R-290 is dissolved in PAG, the solubility of THT in PAG becomes smaller, and THT is more easily released.

[0195] It is considered that when the O / C ratio is less than 0.50, the ratio of polarized atomic groups in the molecular structure of PAG is reduced to less than half, thereby achieving an effect of increasing the amount of THT emission. Therefore, the O / C ratio is preferably less than 0.50.

[0196] From the above results, in order to circulate THT together with R-290 in the refrigerant circuit by suppressing the dissolution of THT in PAG, it is preferable to use PAG having an O / C ratio of less than 0.50.

[0197] In addition, regarding the results shown in Evaluation Test 1, it is believed that even when using hydrocarbons with a carbon number of 1 to 4 other than R-290, sulfur-based odorants other than THT, and refrigeration oils other than PAG, the relationship between the O / C ratio and the odor intensity is obtained in the same manner. The reason is that the amount of sulfur-based odorants dissolved in refrigeration oil is determined by the polarity of the base oil, regardless of the types of hydrocarbons with a carbon number of 1 to 4, sulfur-based odorants, and base oil. It is believed that, as for hydrocarbons with a carbon number of 1 to 4 other than R-290, as described above, they are non-polar molecules with a small dipole moment like R-290, and therefore the same results as R-290 are obtained. It is believed that, as for sulfur-based odorants other than THT, as described above, they are polar molecules with a dipole moment of the same degree as THT, and therefore the same results are obtained. Although the difference in the O / C ratio occurs due to the difference in the type of base oil, the principle of the dissolution of the sulfur-based odorant is not changed.

[0198] <Evaluation Test 4>

[0199] The results of evaluation test 3 confirm that by using PAG as a base oil with a small O / C ratio, the solubility of THT in PAG is reduced, and THT is released together with R-290. However, the difference in odor intensity of the refrigerants PAG3 to 13 cannot be explained. Therefore, using HSP, the correlation between the molecular structure of PAG and the emission amount of THT was studied. The HSP of THT, R-290 and each No. of PAG is shown in Table 9. For the HSP of THT and R-290, the values ​​registered in the database of HSPiP Ver.5.3, which is computer software, are used to calculate, and for the HSP of each No. of PAG, the Van Krevelen method, which is a calculation method installed in HSPiP Ver.5.3, is used to calculate.

[0200] [Table 9]

[0201]

[0202] The HSP distance between R-290 and THT is greater than the HSP distance between PAG and THT, and the solubility of THT in R-290 is smaller than that in PAG. That is, if R-290 is dissolved in PAG, R-290 reduces the solubility of THT in the base oil, so it is considered that the amount of THT dissolved in PAG is reduced.

[0203] In addition, the larger the HSP distance between PAG and THT, the smaller the solubility of THT in PAG, and the smaller the HSP distance between PAG and R-290, the greater the solubility of R-290 in PAG. Therefore, R-290 dissolves more in PAG, and THT is more difficult to dissolve in PAG. That is, it is believed that the larger the difference between the HSP distance between PAG and THT and the HSP distance between PAG and R-290 is, the smaller the amount of THT dissolved in PAG, and the more THT is contained in the refrigerant gas released from the refrigerant circuit. The relationship between the difference between the HSP distance between PAG and THT and the HSP distance between PAG and R-290 and the odor intensity in Evaluation Test 3 is shown in Table 10.

[0204] [Table 10]

[0205] PAG No. O / C Ratio Difference in HSP distance Odor intensity 1 0.60 -7.3 0～1 2 0.53 -6.5 0～1 9 0.36 -1.6 2～3 12 0.35 -1.1 2～3 4 0.43 -0.8 2～3 5 0.43 --0.4 3～4 13 0.33 -0.4 3～4 7 0.39 -0.3 3～4 3 0.43 -0.1 3～4 6 0.42 0.0 3～4 8 0.39 0.3 3～4 11 0.35 1.0 3～4 10 0.35 1.6 3～4

[0206] The results of the above evaluations respectively confirmed that: when the difference between the HSP distance between PAG and THT and the HSP distance between PAG and R-290 was greater than -2.0, the amount of sulfur-based odorant dissolved in the base oil became sufficiently small as described above, and the released refrigerant gas had an odor intensity of greater than 2; and when it was greater than -0.5, the released refrigerant gas had an odor intensity of greater than 3.

[0207] From the above results, in order to circulate THT together with R-290 in the refrigerant circuit, it is preferable to use a PAG having a difference in HSP distance of -2.0 or more, and more preferably a PAG having a difference in HSP distance of -0.5 or more.

[0208] As shown in the results of this test, by using HSP, the solubility of THT in PAG can be confirmed in detail. It should be noted that HSP can explain the solubility between substances without relying on the type of molecule. Therefore, it is believed that the relationship between the difference in the above-mentioned HSP distance and the odor of the refrigerant gas is not limited to PAG, and the same result is obtained for POE, PVE, and hydrocarbon oil. In addition, it is believed that the same result is obtained for other hydrocarbons with a carbon number of 1 to 4, not limited to R-290, and the same result is obtained for sulfur-based odorants other than THT.

[0209] <Evaluation Test 5>

[0210] A commercial household indoor air conditioner (manufactured by Mitsubishi Electric Corporation, indoor unit model MSZ-GV5620S / outdoor unit model MUCZ-G5620S) having a refrigerant circuit was used to recover the refrigerant gas released from the refrigerant circuit. In the refrigerant circuit, 450 g of R-290 as the main component of the refrigerant and 290 mg (643 mass ppm relative to the mass of the refrigerant) of THT as a sulfur-based odorant were sealed. In the compressor, 400 g of a refrigeration oil using the PAG used in the evaluation test 1 (PAG No. 10 in the evaluation test 3) as the base oil was sealed.

[0211] After the household indoor air conditioner was operated, the refrigerant gas was released from between the expansion valve and the evaporator in a stopped state and recovered in a tedala bag (1-2711-05 manufactured by Azwan Co., Ltd.). The recovered refrigerant gas was diluted to 1 / 1000 times with high-purity air (ZERO-A manufactured by Sumitomo Seika Co., Ltd.) and the odor was sensory evaluated. The sensory evaluation was carried out by 5 testers in the same manner as in the evaluation test 3.

[0212] As a result, the odor of the refrigerant gas was odor intensity 3 to 4. For confirmation, the concentration of THT was analyzed using a gas chromatograph mass spectrometer (JMS-K9 manufactured by JEOL Ltd.) in the same manner as in Evaluation Test 1. As a result, THT was contained in the refrigerant gas at a concentration of 80 mass ppm (40 volume ppm). That is, it was confirmed that the THT concentration when diluted 1 / 1000 times with high-purity air was 40 volume ppb, so the odor intensity of Evaluation Test 2 was equivalent to odor intensity 4, which was consistent with the results of the sensory evaluation.

[0213] The above results confirmed that by using PAG having low solubility of THT, suppressing the dissolution of THT in PAG, and circulating THT together with R-290 in the refrigerant circuit, the refrigerant gas released from the refrigerant circuit can be identified by smell.

[0214] It should be noted that the refrigerant, sulfur-based odorant, and refrigeration oil are not limited to those used in evaluation tests 1 to 5. The same applies to the concentration of the sulfur-based odorant. For other sulfur-based odorants, the concentration can be calculated from the O / C ratio of the refrigeration oil, the HSP distance, etc., and appropriately adjusted to obtain a sufficient odor.

[0215] The embodiments and examples disclosed this time should be considered to be illustrative in all aspects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0216] Description of Reference Numerals

[0217] 1 outdoor unit, 2 indoor unit, 3 compressor, 4 condenser, 5 outdoor fan, 6 expansion valve, 7 evaporator, 8 indoor fan, 9 liquid pipe, 10 gas pipe, 11 shell, 12 compression mechanism, 13 motor, 14 suction pipe, 15 discharge pipe, 16 storage, 17 rolling piston, 18 barrel, 19 barrel chamber, 20 upper bearing, 21 discharge hole of upper bearing, 22 muffler space, 23 discharge muffler, 24 discharge hole of muffler, 25 motor rotor, 26 motor stator, 27 oil storage part, 28 drive shaft, 100 refrigerant circuit.

Claims

1. A refrigerating machine oil for a refrigerating cycle device using a refrigerant, wherein: The refrigerant comprises a hydrocarbon having a carbon number of 1 to 4 and a sulfur-based odorant. The refrigeration oil comprises a base oil, The ratio of the number of oxygen atoms to the number of carbon atoms in the molecular structure of the base oil is less than 0.

50. The difference between the HSP distance between the base oil and the sulfur-based odorant and the HSP distance between the base oil and the hydrocarbons having 1 to 4 carbon atoms is -2.0 or more.

2. The refrigerating machine oil according to claim 1, wherein The base oil is at least one selected from oxygen-containing oil and hydrocarbon oil.

3. A refrigerating machine oil for a refrigerating cycle device using a refrigerant, wherein: The refrigerant comprises a hydrocarbon having a carbon number of 1 to 4 and a sulfur-based odorant. The refrigeration oil comprises a base oil, The base oil is at least one selected from oxygen-containing oil and hydrocarbon oil, wherein the oxygen-containing oil does not include polyalkylene glycol. The ratio of the number of oxygen atoms to the number of carbon atoms in the molecular structure of the base oil is less than 0.

50.

4. A refrigerating machine oil for a refrigerating cycle device using a refrigerant, wherein: The refrigerant comprises a hydrocarbon having a carbon number of 1 to 4 and a sulfur-based odorant. The refrigeration oil comprises a base oil, The base oil includes a polyalkylene glycol represented by the following Chemical Formula 1, The ratio of the number of oxygen atoms to the number of carbon atoms in the molecular structure of the base oil is less than 0.

50. In the chemical formula 1, m and n are respectively a value greater than or equal to 0 representing the average number of ethylene oxide groups and propylene oxide groups, 1 and R 2 is a hydrogen atom or a hydrocarbon chain having 1 or more carbon atoms, satisfying the following formulas (1) and (2): m+n≤100· · · (1) n / (m+n)≥0.20· · · (2).

5. A composition for a refrigeration cycle device, comprising: a hydrocarbon having 1 to 4 carbon atoms, a sulfur-based odorant, and the refrigeration oil according to any one of claims 1 to 4.

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