Refrigeration cycle device

Abstract

Provided is a refrigeration cycle device with which it is possible to recognize leakage of a refrigerant through the olfactory sense in consideration of reducing a sulfur-based odorant corresponding to an operation condition.　A refrigeration cycle device according to the present disclosure comprises a refrigerant circuit including a compressor. A refrigerant is sealed inside the refrigerant circuit. The refrigerant contains a C1-C4 hydrocarbon and a sulfur-based odorant. The interior of the compressor is filled with a refrigeration machine oil. The initial concentration of the sulfur-based odorant in the refrigerant satisfies formula 1, A applied to formula 1 satisfies formula 2, D satisfies formula 3, F satisfies formula 4, C applied to formula 3 satisfies formula 5, and E applied to formula 4 satisfies formula 6, where [Odo]0 (mass ppm) is the initial concentration of the sulfur-based odorant in the refrigerant, T (K) is the outside air temperature in an installation environment, Mref (g) is the sealing amount of the refrigerant, Moil (g) is the filling amount of the refrigerator oil, MWref is the molecular weight of the hydrocarbon, MWodo is the molecular weight of the sulfur-based odorant, [Odo]min (mass ppm) is the olfactory threshold value for the sulfur-based odorant, and [Ref]LHL (vol%) is the explosion lower limit concentration of the hydrocarbon.

Description

Refrigeration Cycle Equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] Currently, refrigerants used in refrigeration cycle devices are regulated by, for example, the Fluorocarbons Emission Control Act (enforced in April 2015). Specifically, an upper limit is set on the global warming potential (GWP) value of the refrigerants used. For this reason, the use of refrigerants with lower GWP is required.

[0003] In recent years, hydrocarbons with 1 to 4 carbon atoms, such as R-290 (propane), R-1270 (propylene), R-600 (butane), and R-600a (isobutane), have been considered as refrigerants with low GWP values. Hydrocarbons with 1 to 4 carbon atoms have even lower GWP values ​​than saturated fluorinated hydrocarbon compounds (hydrofluorocarbons), which are refrigerants with relatively low GWP values.

[0004] However, hydrocarbons with 1 to 4 carbon atoms have higher flammability than hydrofluorocarbons. For example, in the international standard ISO-817, which defines the safety grades of refrigerants, R-32 (difluoromethane), 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).

[0005] When a highly flammable refrigerant such as a hydrocarbon having 1 to 4 carbon atoms is used as the refrigerant for the refrigeration cycle device, it is preferable that measures be taken to make the refrigerant olfactory or visually recognizable.

[0006] As a measure to make a refrigerant detectable by olfaction, a method is known in which a sulfur-based odorant is mixed into the refrigerant and a refrigerant leak is detected by an unpleasant odor. When a highly polar refrigerating machine oil is used, the sulfur-based odorant dissolves in the refrigerating machine oil inside the compressor. For example, Patent Document 1 discloses a refrigeration cycle device that suppresses the dissolution of the sulfur-based odorant into the refrigerating machine oil and makes it possible to detect a refrigerant leak by olfaction.

[0007] International Publication No. 2023 / 079738

[0008] In the above-described refrigeration cycle device, the concentration of the sulfur-based odorant in the refrigerant is adjusted taking into consideration dissolution in the refrigeration oil and dilution after leakage, thereby making it possible to recognize the refrigerant by olfactory sense.

[0009] However, the inventors discovered that the amount of sulfur-based odorant dissolved in the refrigeration oil changes depending on the operating conditions of the refrigeration cycle device. When the amount of sulfur-based odorant dissolved in the refrigeration oil increases, the amount of sulfur-based odorant circulating in the refrigerant circuit together with the refrigerant decreases, and even when the refrigerant is released from the refrigeration cycle device, it becomes difficult to detect the refrigerant by olfactory sense.

[0010] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a refrigeration cycle device that takes into account the reduction of sulfur-based odorants depending on operating conditions and makes it possible to detect refrigerant leakage through the sense of smell.

[0011] The refrigeration cycle device according to the present disclosure includes a refrigerant circuit including a compressor, a refrigerant is sealed inside the refrigerant circuit, the refrigerant includes hydrocarbons having 1 to 4 carbon atoms and a sulfur-based odorant, the compressor is filled with refrigerating machine oil, and an initial concentration of the sulfur-based odorant in the refrigerant is set to [Odo] ０ (mass ppm), the outside air temperature in the installation environment is T (K), and the amount of refrigerant charged is M ｒｅｆ (g), the amount of refrigerating machine oil filled is M ｏｉｌ (g), the molecular weight of the hydrocarbon is MW ｒｅｆ , the molecular weight of the sulfur-based odorant is MW ｏｄｏ The olfactory threshold of sulfur-based odorants is [Odo] ｍｉｎ (ppm by volume), the lower flammable limit concentration of hydrocarbons is [Ref] ＬＦＬ (vol %), the initial concentration of the sulfur-based odorant in the refrigerant satisfies the following mathematical formula 1, A given by mathematical formula 1 satisfies mathematical formula 2, D satisfies mathematical formula 3, F satisfies mathematical formula 4, C given by mathematical formula 3 satisfies mathematical formula 5, and E given by mathematical formula 4 satisfies mathematical formula 6.

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018] According to the present disclosure, it is possible to provide a refrigeration cycle device that takes into account the reduction of sulfur-based odorants depending on operating conditions and allows refrigerant leakage to be detected by the sense of smell.

[0019] 1 is a schematic diagram showing an example of a refrigeration cycle apparatus according to embodiment 1. FIG. 2 is a cross-sectional schematic diagram showing an example of a compressor of the refrigeration cycle apparatus according to embodiment 1. FIG. 3 is a graph showing the relationship between the outside air temperature and the concentration of tetrahydrothiophene in the recovered refrigerant gas. FIG. 4 is a graph showing the relationship between the mass fraction of refrigerant relative to refrigerating machine oil and the concentration of tetrahydrothiophene in the recovered refrigerant gas. FIG. 5 is a graph showing the relationship between the concentration of THT in the enclosed refrigerant gas and the concentration of tetrahydrothiophene in the recovered refrigerant gas. FIG. 6 is a graph showing a comparison between the predicted result using Equation 16 and the experimental result for the concentration of tetrahydrothiophene in the recovered refrigerant gas. FIG. 7 is a graph showing the change over time in the concentration of tetrahydrothiophene in the recovered refrigerant gas. τ ０．３質量ｐｐｍ 10 is a graph showing the relationship between the natural logarithm of the discharge temperature and the reciprocal of the average value of the discharge temperature.

[0020] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, dimensional relationships such as length, width, thickness, and depth have been appropriately changed for clarity and simplification of the drawings, and do not represent actual dimensional relationships. In the drawings, the same or corresponding parts are designated by the same reference numerals, and their descriptions will not be repeated.

[0021] First Embodiment First, a brief overview of the refrigeration cycle apparatus of this embodiment will be described. Fig. 1 is a schematic diagram showing an example of a refrigeration cycle apparatus according to the first embodiment. The outdoor unit 1 includes a compressor 3, a condenser 4, an outdoor blower 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 blower 8, etc., and the expansion valve 6 and the evaporator 7 are connected by piping.

[0022] 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.

[0023] The refrigerant circuit 100 is formed by the above-described configuration of the refrigeration cycle device, and the refrigerant circulates within the refrigerant circuit 100 via the liquid pipe 9 and the gas pipe 10 .

[0024] The compressor 3 compresses the gaseous refrigerant in the gas pipe 10. The condenser 4 cools the gaseous refrigerant compressed by the compressor 3 to form a high-pressure liquid refrigerant or a two-phase gas-liquid refrigerant. The expansion valve 6 reduces the pressure of the high-pressure liquid refrigerant or the two-phase gas-liquid refrigerant. The evaporator 7 heats the reduced-pressure refrigerant to form a low-pressure gaseous refrigerant. The compressor 3 draws in the low-pressure gaseous refrigerant that has been converted by the evaporator 7 and compresses it again.

[0025] The outdoor fan 5 is a component that sends air to the condenser 4 and is provided to promote heat exchange between the refrigerant flowing through the condenser 4 and the air, thereby absorbing or releasing heat. The indoor fan 8 is a component that sends air to the evaporator 7 and is provided to promote heat exchange between the refrigerant flowing through the evaporator 7 and the air, thereby absorbing or releasing heat.

[0026] In this embodiment, a configuration for performing heat exchange between the condenser 4 and the evaporator 7 and air is described, but this is not limited to this, and for example, the configuration may be such that heat exchange is performed with a liquid such as water instead of air.

[0027] Furthermore, in this embodiment, a configuration in which the evaporator 7 is provided inside the indoor unit 2 is described, but this is not limited to this, and for example, the condenser 4 may be arranged indoors and the evaporator 7 may be arranged outdoors.

[0028] The outdoor unit 1 as described above may be provided with, for example, a four-way valve or a combination of multiple valves and a switching mechanism for switching between the suction pipe and the discharge pipe of the compressor 3. 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 use heat from outside the room to heat the room.

[0029] The refrigeration cycle device may be, for example, a device capable of both cooling and heating, a device capable of only cooling, or a device capable of only heating. The use of the refrigeration cycle device according to the present embodiment is not limited to air conditioning, but may also be for freezing, refrigeration, hot water supply, etc.

[0030] In the present embodiment, a configuration in which the expansion valve 6 is provided in the indoor unit 2 has been described, but the present invention is not limited to this, and for example, the expansion valve 6 may be provided in the outdoor unit 1. Also, 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.

[0031] <Refrigerant> Next, the refrigerant sealed inside the refrigerant circuit in this embodiment will be described. The refrigerant contains a main component that functions as a refrigerant, and further contains a sulfur-based odorant for detecting refrigerant leakage.

[0032] Here, the "main component" refers to the components of the refrigerant excluding sulfur-based odorants and impurities (such as air, moisture, and by-products that may be mixed in during the synthesis and refining of refrigerant compounds). 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.

[0033] The main component that functions as a refrigerant is a hydrocarbon having one to four carbon atoms. Examples of hydrocarbons having one to four carbon atoms include R-290 (propane), R-1270 (propylene), R-600 (butane), and R-600a (isobutane). Preferably, the hydrocarbon having one to four carbon atoms is propane, propylene, or a mixture thereof. This is because these have operating pressures suitable for use in refrigeration cycle devices. From the perspective of oxidation stability, propane is more preferable. According to the IPCC Sixth Assessment Report, propane has an extremely low GWP value of 0.02 and high cooling performance, which can contribute to reducing the environmental impact during the manufacture and operation of refrigeration cycle devices.

[0034] The refrigerant may further contain a halogenated hydrocarbon. Examples of halogenated hydrocarbons include chlorofluorocarbons, hydrochlorofluorocarbons, hydrofluorocarbons, hydrofluoroolefins, hydrochlorofluoroolefins, and fluoroiodocarbons. Halogenated hydrocarbons have lower flammability than hydrocarbons due to the substitution of hydrogen atoms with halogen atoms, and mixing can reduce the flammability of the refrigerant. The halogenated hydrocarbon may be mixed with a hydrocarbon having 1 to 4 carbon atoms and charged into the refrigerant circuit, or an additional hydrocarbon having 1 to 4 carbon atoms may be charged into a refrigerant circuit that is already charged with a halogenated hydrocarbon or that has a small amount of halogenated hydrocarbon remaining.

[0035] The halogenated hydrocarbon preferably has an operating pressure similar to that of hydrocarbons having 1 to 4 carbon atoms. This increases the azeotropic property with the hydrocarbons having 1 to 4 carbon atoms, which are the main components of the refrigerant, and enables high cooling performance to be obtained. Such halogenated hydrocarbons are halogenated hydrocarbons having 1 to 4 carbon atoms, and more preferably halogenated hydrocarbons having 1 to 3 carbon atoms. This is because the halogenated hydrocarbons have larger molecules than hydrocarbons due to halogenation, and therefore have a lower operating pressure than hydrocarbons with the same carbon number. Examples of 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, and HFO- Examples of such HFOs include HFO-1225ye(Z), HFO-1225ye(E), HFO-1225zc, HFO-1234yf, HFO-1234ze(E), HFO-1234ze(Z), HFO-1234ye(Z), HFO-1234ye(E), HFO-1243zf, HFO-1252zf, HFO-1261yf, FIC-13I1 (CF3I), HCFC-22, and CFC-12.

[0036] The refrigerant may also contain carbon dioxide (R-744). Carbon dioxide has a low GWP of 1, which can contribute to reducing the environmental impact during the manufacture of refrigeration cycle devices. In addition, because carbon dioxide is non-flammable, mixing it can reduce the flammability of the refrigerant.

[0037] If air is contained in the refrigerant, it may accelerate deterioration of the refrigerant, sulfur-based odorants, the refrigerating machine oil described below, the materials inside the compressor 3, etc., so it is preferable to remove the air from inside the refrigerant circuit before filling the refrigerant circuit with the refrigerant.

[0038] (Sulfur-Based Odorant) The sulfur-based odorant blended into the refrigerant is an odorant containing elemental sulfur. Examples of sulfur-based odorants include mercaptans, sulfides, and thiophenes. Examples of mercaptans include methyl mercaptan (MM), ethyl mercaptan (EM), normal propyl mercaptan (NPM), isopropyl mercaptan (IPM), and tertiary butyl mercaptan (TBM). Examples of sulfides include dimethyl sulfide (DMS), diethyl sulfide (DES), and methyl ethyl sulfide (MES). Examples of thiophenes include tetrahydrothiophene (THT). These sulfur-based odorants are compounds that have a proven track record of use in fuel gases and have an unpleasant odor. These sulfur-based odorants may be used alone or in combination of two or more.

[0039] The sulfur-based odorant is preferably EM, NPM, IPM, TBM, DMS, MES, THT, or a mixture thereof, which are also used in fuel gas for home use. By mixing a sulfur-based odorant used in fuel gas for home use with the refrigerant, refrigerant leakage can be easily detected by the unpleasant odor characteristic of the sulfur-based odorant.

[0040] The initial concentration of the sulfur-based odorant in the refrigerant is such that refrigerant leakage from the refrigerant circuit can be easily detected and the odor is not excessively unpleasant. Here, the initial concentration of the sulfur-based odorant in the refrigerant is a concentration calculated from the ratio of the mass of the sulfur-based odorant to the mass of the refrigerant charged in the refrigerant circuit. The sulfur-based odorant dissolves in the refrigerant oil (described below) inside the compressor 3. The amount of sulfur-based odorant dissolved in the refrigerant oil varies depending on the operating conditions of the refrigeration cycle device, such as the outside air temperature in the installation environment and the mass fraction of the refrigerant relative to the refrigerant oil. Therefore, the initial concentration of the sulfur-based odorant in the refrigerant is determined taking into account the reduction of the sulfur-based odorant depending on the operating conditions of the refrigeration cycle device. Details of the initial concentration of the sulfur-based odorant in the refrigerant will be described later.

[0041] As the sulfur-based odorant, THT is more preferable. THT is chemically stable compared to mercaptans and sulfides, and is less likely to cause decomposition or corrosion reactions in the refrigerant circuit. Furthermore, since THT has a low melting point of -96°C, it is less likely to solidify in the refrigerant circuit.

[0042] The sulfur-based odorant may be a compound that is not used as an odorant for fuel gas, as long as it contains sulfur element. For example, hydrogen sulfide, carbonyl sulfide, etc. have a distinctive unpleasant odor similar to the above-mentioned sulfur-based odorants, and can easily detect refrigerant leaks.

[0043] The refrigerant may further contain a sulfur-free odorant. This is because, like THT, sulfur-free odorants are less likely to cause metal corrosion reactions in the refrigerant circuit. Examples of sulfur-free odorants include cyclohexene, acrylic esters, ammonia, amines, pyrazines, and norbornenes. In addition to these sulfur-free odorants, the refrigerant may further contain a compound with a unique odor as an odorant.

[0044] <Compressor> In this embodiment, the refrigeration cycle device includes a compressor 3. A refrigerant passes through the inside of the compressor 3. The inside of the compressor 3 is filled with refrigerating machine oil. The refrigerating machine oil contains a base oil.

[0045] Fig. 2 is a cross-sectional schematic diagram showing an example of a compressor 3 of a refrigeration cycle apparatus according to this embodiment. As shown in Fig. 2, the compressor 3 includes a shell 11. The shell 11 includes a compression mechanism 12 therein and an electric motor 13 that drives the compression mechanism 12. The shell 11 is also connected to a suction pipe 14 for allowing the refrigerant to flow into the interior and a discharge pipe 15 for allowing the refrigerant to flow out. An accumulator 16 is connected upstream of the suction pipe 14 to separate the refrigerant into gas and liquid and send the vapor to the suction pipe 14.

[0046] The refrigerant that has passed through the accumulator 16 flows from the suction pipe 14 into the compression mechanism 12 in the shell 11. The refrigerant that has flowed into the compression mechanism 12 is compressed to a high temperature and high pressure, and is then discharged from the discharge pipe 15. In other words, the compression mechanism 12 is configured to compress the refrigerant that has flowed into the shell 11 from the suction pipe 14 and discharge it from the discharge pipe 15.

[0047] The compression mechanism 12 is a rotary type compression mechanism that is made up of a combination of a rolling piston 17, a vane (not shown), etc. The eccentric rotation of the rolling piston 17 changes the volume of the space surrounded by the inner circumferential surface of the cylinder chamber 19 of the cylinder 18, the outer circumferential surface of the rolling piston 17, and the vane (not shown), thereby compressing the refrigerant.

[0048] The compressed refrigerant is discharged from discharge hole 21 of upper bearing 20 into muffler space 22, and then from discharge hole 24 of discharge muffler 23 into shell 11. The discharged refrigerant passes through gaps in motor 13 (gaps between motor rotor 25 and motor stator 26, grooves on the outer peripheral surface of motor stator 26, etc.), and then is discharged from discharge pipe 15 to the downstream side of refrigerant circuit 100.

[0049] The compressor 3 has sliding parts inside the compression mechanism 12. To lubricate the sliding parts, refrigeration oil is stored in an oil reservoir 27 located below the compressor 3. The refrigeration oil stored in the oil reservoir 27 is supplied to the sliding parts inside the compression mechanism 12 by pump action through an oil supply hole (not shown) provided in the drive shaft 28. Since the refrigeration oil comes into contact with the refrigerant inside the compressor 3, part of the refrigerant dissolves in the refrigeration oil.

[0050] <Refrigerating Machine Oil> Next, in this embodiment, the refrigerating machine oil filled to lubricate the inside of the compressor 3 will be described. The refrigerating machine oil includes a base oil. The base oil is at least one oil selected from the group consisting of oxygen-containing oils and hydrocarbon oils. Examples of oxygen-containing oils include polyalkylene glycol (PAG), polyol ester (POE), and polyvinyl ether (PVE). Examples of hydrocarbon oils include polyalphaolefin (PAO), alkylbenzene (AB), alkylnaphthalene (AN), and mineral oil.

[0051] Here, the base oil is a component that lubricates the inside of the compressor 3 due to the kinematic viscosity of the material. The base oil is preferably a material that has a kinematic viscosity higher than that of the refrigerant, and the kinematic viscosity at 40°C is preferably 5 mm ２ / s or more 250mm ２ / s or less is more preferable. When the base oil has a kinematic viscosity higher than that of the refrigerant, the kinematic viscosity of the base oil is sufficient to lubricate the sliding parts of the compressor 3 and not significantly reduce the cooling efficiency of the refrigeration cycle device. The kinematic viscosity of the base oil can be adjusted to be within the above range by changing the molecular structure or degree of polymerization of each base oil.

[0052] (Additives in Oil) The refrigerating machine oil may contain, as additives in oil, an antioxidant, an acid scavenger, and an extreme pressure agent (antiwear agent).

[0053] Examples of antioxidants include phenolic antioxidants 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 amine antioxidants such as phenyl-α-naphthylamine and N,N'-di-phenyl-p-phenylenediamine. Antioxidants not only inhibit deterioration of refrigerating machine oils, but also have the effect of inhibiting oxidative deterioration of sulfur-based odorants.

[0054] The content of the antioxidant in the refrigerating machine 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. If the content of the antioxidant in the refrigerating machine oil is less than 0.05% by mass, the antioxidant may not be effective. If the content of the antioxidant in the refrigerating machine oil is more than 2% by mass, the kinematic viscosity of the refrigerating machine oil may decrease, or the antioxidant may deteriorate and block the refrigerant circuit as an impurity.

[0055] Examples of acid scavengers include epoxy compounds such as phenyl glycidyl ether, alkyl glycidyl ester, alkyl glycidyl ether, alkylene glycol glycidyl ether, cyclohexene oxide, α-olefin oxide, and epoxidized soybean oil. Preferred acid scavengers are alkyl glycidyl ester, alkyl glycidyl ether, and α-olefin oxide. Acid scavengers capture acids generated by deterioration of refrigerating machine oil and organic materials (insulating films, sealing materials, etc.) present in the refrigerant circuit, and are therefore effective in suppressing deterioration of sulfur-based odorants due to acids.

[0056] The content of the acid scavenger in the refrigerating machine oil is preferably 0.05% by mass to 10% by mass, more preferably 0.1% by mass to 10% by mass. If the content of the acid scavenger in the refrigerating machine oil is less than 0.05% by mass, the effect of the acid scavenger may not be obtained. If the content of the acid scavenger in the refrigerating machine oil is more than 10% by mass, the kinematic viscosity of the refrigerating machine oil may decrease, or the acid scavenger may deteriorate and block the refrigerant circuit as an impurity.

[0057] Examples of extreme pressure agents (antiwear agents) include phosphorus-based extreme pressure agents such as phosphate esters, thiophosphate esters, acid phosphate esters, phosphites, acid phosphites, and amine salts thereof. Phosphate esters, thiophosphate esters, or mixtures thereof are preferred as extreme pressure agents (antiwear agents). Specifically, tricresyl phosphate (O=P-(OC7H7)3), triphenyl phosphorothioate (S=P-(OC6H5)3), triphenyl phosphate (O=P-(OC6H5)3), derivatives thereof, or mixtures thereof are preferred. Extreme pressure agents reduce friction in the sliding parts of the compressor 3, thereby suppressing the deterioration of sulfur-based odorants due to frictional heat.

[0058] The content of the extreme pressure agent in the refrigerating machine 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. If the content of the extreme pressure agent in the refrigerating machine oil is less than 0.05% by mass, the effect of the extreme pressure agent may not be obtained. If the content of the extreme pressure agent in the refrigerating machine oil exceeds 5% by mass, the extreme pressure agent may corrode metals, reduce the kinematic viscosity of the refrigerating machine oil, or deteriorate and act as impurities to clog the refrigerant circuit.

[0059] The refrigerating machine oil may also contain an oxygen scavenger. Examples of oxygen scavengers include sulfur-containing aromatic compounds such as 4,4'-thiobis(3-methyl-6-tert-butylphenol), diphenyl sulfide, dioctyldiphenyl sulfide, dialkyldiphenylene sulfide, benzothiophene, dibenzothiophene, phenothiazine, benzothiapyran, thiapyran, thianthrene, dibenzothiapyran, and diphenylene disulfide; aliphatic unsaturated compounds such as various olefins, dienes, and trienes; and cyclic terpenes having unsaturated bonds such as α-pinene, β-pinene, limonene, and phellandrene. Preferred oxygen scavengers include aliphatic unsaturated compounds and cyclic terpenes having unsaturated bonds. Oxygen scavengers not only inhibit oxidative degradation of refrigerating machine oils, but also have the effect of inhibiting oxidative degradation of sulfur-based odorants.

[0060] The content of the oxygen scavenger in the refrigerating machine 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 3% by mass or less. If the content of the oxygen scavenger in the refrigerating machine oil is less than 0.05% by mass, the effect of the oxygen scavenger may not be obtained. If the content of the oxygen scavenger in the refrigerating machine oil is more than 5% by mass, the kinematic viscosity of the refrigerating machine oil may decrease, or the oxygen scavenger may deteriorate and block the refrigerant circuit as an impurity.

[0061] (Others) The refrigerating machine oil may contain a fluorescent agent, a coloring agent, etc., so that the refrigerant and the refrigerating machine oil can be visually detected. The fluorescent agent and the coloring agent are preferably added in an amount equal to or less than the saturated solubility of the refrigerating machine oil, so as to prevent precipitation at low temperatures.

[0062] If the refrigerating machine oil contains moisture, it may accelerate the deterioration of the refrigerant, the refrigerating machine oil, metals in the refrigerant circuit, organic materials (polyester, etc.) in the refrigerant circuit, etc., so the moisture content of the refrigerating machine oil to be filled needs to be controlled to 300 ppm by mass or less, preferably 100 ppm by mass or less.

[0063] <Initial Concentration of Sulfur-Based Odorant> As described above, sulfur-based odorants dissolve in refrigerating machine oil. When the amount of sulfur-based odorant circulating in the refrigerant circuit together with the refrigerant decreases due to dissolution in the refrigerating machine oil, it becomes difficult to detect refrigerant leakage by olfaction.

[0064] Furthermore, the amount of sulfur-based odorant dissolved in refrigerating machine oil varies depending on the operating conditions of the refrigeration cycle device, such as the outside air temperature in the installation environment and the mass fraction of the refrigerant relative to the refrigerating machine oil. Specifically, as shown in (Evaluation Test 1) below, the lower the outside air temperature in the installation environment, the greater the amount of sulfur-based odorant dissolved in refrigerating machine oil, making it more difficult to detect refrigerant leakage by olfaction. Furthermore, as shown in (Evaluation Test 2) below, the smaller the mass fraction of the refrigerant relative to the refrigerating machine oil, the greater the amount of sulfur-based odorant dissolved in refrigerating machine oil, making it more difficult to detect refrigerant leakage by olfaction. Therefore, the initial concentration of the sulfur-based odorant in the refrigerant is determined as described below, taking into account the amount of reduction of the sulfur-based odorant, which varies depending on the operating conditions of the refrigeration cycle device.

[0065] The initial concentration of the sulfur-based odorant in the refrigerant satisfies the following formula 1. A given by formula 1 satisfies the following formula 2, D satisfies formula 3, and F satisfies formula 4, C given by formula 3 satisfies formula 5, and E given by formula 4 satisfies formula 6. Here, the initial concentration of the sulfur-based odorant in the refrigerant is [Odo] ０ (mass ppm), the outside air temperature in the installation environment is T (K), and the amount of refrigerant charged is M ｒｅｆ (g), the amount of refrigerating machine oil filled is M ｏｉｌ (g), the molecular weight of the hydrocarbon is MW ｒｅｆ , the molecular weight of the sulfur-based odorant is MW ｏｄｏ The olfactory threshold of sulfur-based odorants is [Odo] ｍｉｎ (ppm by volume), the lower flammable limit concentration of hydrocarbons is [Ref] ＬＦＬ (volume %).

[0066] The value A in Equation 2 is derived from the evaluation tests 1, 2, and 3 described below, and is determined by the ambient temperature T in the installation environment, the mass fraction M of the refrigerant relative to the refrigerating machine oil, and ｒｅｆ / (M ｒｅｆ +M ｏｉｌ ) is used to predict the concentration of the sulfur-based odorant that decreases depending on the concentration of hydrocarbons contained in the refrigerant. C shown in Equation 5 is the minimum volume ppm concentration of the sulfur-based odorant required to recognize the refrigerant by olfaction when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant becomes 0.2 times the lower flammability limit concentration. E shown in Equation 6 is the volume ppm concentration of the sulfur-based odorant when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant becomes 0.2 times the lower flammability limit concentration, and the odor index of the refrigerant exceeds 18, which is the upper limit of "easily detectable odors." Equations 3 and 4 are equations for converting the volume ppm concentrations C and E of the sulfur-based odorant shown in Equation 5 and Equation 6 into mass ppm concentrations D and F, respectively. Here, the reason why an odorant is mixed so that the refrigerant can be detected by the sense of smell when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant reaches 0.2 times the lower flammable limit is that standards for fuel gases such as ISO 13734 and NFPA 58 require measures to make the refrigerant detectable by the sense of smell at 0.2 times the lower flammable limit by mixing an odorant.

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] Initial concentration of sulfur-based odorant in refrigerant [Odo] ０ is within the range that satisfies the above-mentioned formula 1, the amount of the sulfur-based odorant circulating in the refrigerant circuit together with the refrigerant is ｒｅｆ / (M ｒｅｆ +M ｏｉｌ Even when the concentration of the sulfur-based odorant in the refrigerant is reduced depending on the operating conditions of the refrigeration cycle device, including the conditions of (1) and (2), the odor is detectable by the sense of smell and is not excessively unpleasant. ０ When the above formula 1 is satisfied, the reduction of the sulfur-based odorant due to dissolution into the refrigerating machine oil can be taken into consideration according to the operating conditions, and the refrigerant leakage can be recognized by the sense of smell.

[0074] Furthermore, the sulfur-based odorant circulating through the refrigerant circuit together with the refrigerant decreases due to deterioration, making it difficult to detect refrigerant leakage by olfaction. Specifically, as shown in Evaluation Test 4 described below, the higher the refrigerant discharge temperature during operation of the refrigeration cycle device and the longer the operating time of the refrigeration cycle device, the more the sulfur-based odorant circulating through the refrigerant circuit together with the refrigerant is thermally decomposed, making it difficult to detect refrigerant leakage by olfaction. Therefore, it is more preferable to determine the initial concentration of the sulfur-based odorant in the refrigerant as described below, taking into account the amount of decrease of the sulfur-based odorant, which changes depending on the operating conditions of the refrigeration cycle device, including the refrigerant discharge temperature and operating time, in addition to the outside air temperature and the mass fraction of the refrigerant relative to the refrigeration oil in the installation environment.

[0075] It is more preferable that the initial concentration of the sulfur-based odorant in the refrigerant satisfies the following formula 7. G given by formula 7 satisfies the following formula 8. Here, the average discharge temperature of the refrigerant is T ｄ (K) The operating time of the refrigeration cycle device is t (hr).

[0076] The value G in Equation 8 is derived from the evaluation test 4 described later, and is the average discharge temperature T ｄ The calculation is for predicting the concentration of the sulfur-based odorant that decreases according to the operating time t of the refrigeration cycle device.

[0077]

[0078]

[0079] Initial concentration of sulfur-based odorant in refrigerant [Odo] ０ is within the range that satisfies the above-mentioned formula 7, the amount of the sulfur-based odorant circulating in the refrigerant circuit together with the refrigerant is ｒｅｆ / (M ｒｅｆ +M ｏｉｌ ) plus the average discharge temperature T ｄ Even when the initial concentration [Odo] of the sulfur-based odorant in the refrigerant is reduced depending on the operating conditions of the refrigeration cycle device, including the operating time t of the refrigeration cycle device, the odor is still detectable by the sense of smell and is not excessively unpleasant. ０ When the above formula 7 is satisfied, the reduction of the sulfur-based odorant due to dissolution in the refrigerating machine oil and deterioration can be taken into consideration according to the operating conditions, and it is possible to detect refrigerant leakage by olfactory sense.

[0080] Next, when the refrigerant is propane and the sulfur-based odorant is THT, the initial concentration [Odo] of the sulfur-based odorant in the refrigerant ０ As described above, it is desirable to use propane as the refrigerant and THT as the sulfur-based odorant. When the refrigeration cycle device is used under the operating conditions shown in Table 1, the initial concentration [Odo] of the sulfur-based odorant in the refrigerant is ０It is preferable that the following formula 9 is satisfied. Formula 9 is an equation obtained by applying the operating conditions listed in Table 1 to Formula 7. The operating conditions listed in Table 1 are examples of operating conditions under which the sulfur-based odorant is likely to be reduced. Specifically, examples of operating conditions under which the amount of sulfur-based odorant dissolved in the refrigerating machine oil increases include a relatively low outside air temperature and a relatively small mass fraction of refrigerant to the refrigerating machine oil, and examples of conditions under which the amount of sulfur-based odorant reduced increases include a relatively high discharge temperature and a relatively long operating time.

[0081]

[0082]

[0083] The refrigerant is propane, the sulfur-based odorant is THT, and the initial concentration of the sulfur-based odorant (THT) in the refrigerant [Odo] ０ is within the range that satisfies the above-mentioned formula 9, even under operating conditions where the sulfur-based odorant (THT) is likely to decrease, when the refrigerant is diluted to 0.2 times the lower flammability limit concentration of propane, it is possible to detect a refrigerant leak by olfactory sense. ０ is within the range that satisfies the above formula 9, the odor will not be excessively unpleasant when the refrigerant is diluted to 0.2 times the lower flammability limit concentration of propane.

[0084] Here, when THT dissolves in refrigerating machine oil, it reduces the viscosity of the refrigerating machine oil. Refrigerating machine oil is required to have a certain viscosity in order to lubricate sliding parts, so when the refrigerant is propane and the sulfur-based odorant is THT, it is more preferable that the initial concentration of the sulfur-based odorant (THT) in the refrigerant be 10,000 (ppm by mass) or less. In other words, when the refrigerant is propane and the sulfur-based odorant is THT, it is preferable that the initial concentration of the sulfur-based odorant (THT) in the refrigerant satisfy the following mathematical formula 12. When the refrigerant is propane and the sulfur-based odorant is THT, it is preferable that the initial concentration of the sulfur-based odorant (THT) in the refrigerant be less than 10,000 (ppm by mass). In other words, when the refrigerant is propane and the sulfur-based odorant is THT, it is preferable that the initial concentration of the sulfur-based odorant (THT) in the refrigerant satisfy the following mathematical formula 10.

[0085] The refrigerant is propane, the sulfur-based odorant is THT, and the initial concentration of the sulfur-based odorant (THT) in the refrigerant [Odo] ０ is within a range that satisfies the above-mentioned formula 10, even under operating conditions in which the sulfur-based odorant (THT) is likely to decrease, when the refrigerant is diluted to 0.2 times the lower flammability limit concentration of propane, it is possible to detect refrigerant leakage by olfactory sense, and it is possible to ensure the reliability of the lubricating function of sliding parts, which is the role of refrigeration oil.

[0086] In the above formulas 1 and 7, the initial concentration of the sulfur-based odorant in the refrigerant [Odo] ０ The lower limit of the sulfur-based odorant is the olfactory threshold [Odo] ｍｉｎ The olfactory threshold of sulfur-based odorants [Odo] is determined based on the following: ｍｉｎ is the minimum concentration that can be detected by the human sense of smell, and is a value determined for each chemical substance through olfactory measurements. The olfactory threshold is divided into a detection threshold, which is the minimum concentration at which a person can detect an odor without knowing what it is, and a recognition threshold, which is the minimum concentration at which a person can detect what the odor is. It is empirically known that the detection threshold is about 10 times the detection threshold. For this reason, in order for the general public to be able to reliably detect a refrigerant leak by their sense of smell, the initial concentration [Odo] of a sulfur-based odorant is empirically set to ０ The lower limit of this is the olfactory threshold [Odo] ｍｉｎ Therefore, in order to ensure that an ordinary person can detect a refrigerant leak by smell, the initial concentration of the sulfur-based odorant in the refrigerant [Odo] ０ may be set to satisfy the following formula 11.

[0087]

[0088] Furthermore, in order to more reliably detect refrigerant leakage by olfactory sense, the initial concentration of the sulfur-based odorant [Odo] ０ The lower limit value of the formula 11 may be set to twice the value of the formula 11. In other words, in order to more reliably detect the refrigerant leakage by the sense of smell, the initial concentration [Odo] of the sulfur-based odorant is ０may be set to satisfy the following formula 12. This is because, according to the Weber-Fechner law, which states that the relationship between the concentration of an odorant and the odor intensity has a logarithmic correlation, doubling the concentration has the effect of moderately increasing the odor intensity to a degree that is less than double.

[0089]

[0090] In the above-described refrigeration cycle device, a rotary compressor is used as the compressor 3, but this is not limited to this. For example, a low-pressure shell type or high-pressure shell type scroll compressor or screw compressor may be used as the compressor 3.

[0091] The present disclosure will be described in detail below with reference to examples, but the present disclosure is not limited to these examples.

[0092] <Equation 1> First, to explain Equation 1, (Evaluation Test 1), (Evaluation Test 2), and (Evaluation Test 3) will be explained.

[0093] (Evaluation Test 1) In order to evaluate the influence of the outside air temperature T in the installation environment on the amount of sulfur-based odorant circulating in the refrigerant circuit together with the refrigerant, a refrigerant gas mixture containing a refrigerant, a sulfur-based odorant, and a refrigerating machine oil was prepared under the conditions shown in Table 2.

[0094]

[0095] The refrigerant gas was sealed in a test container and stirred by shaking, and then placed in a small environmental test chamber (SH-221 manufactured by Espec Corporation) to adjust the temperature. After stabilizing the temperature of the test container at the value shown in Table 3, a pressure gauge was connected to measure the internal pressure of the container, and the refrigerant gas was then collected in a Tedlar bag (1-2711-05 manufactured by AS ONE Corporation). The concentration of THT in the collected refrigerant gas was analyzed using a gas chromatograph mass spectrometer (JMS-K9 manufactured by JEOL Ltd.).

[0096] Table 3 shows the temperature of the test container (outside air temperature T in the installation environment), the container internal pressure P, and the THT concentration [Odo] in the recovered refrigerant gas. Figure 3 shows the relationship between the outside air temperature T in the installation environment and the THT concentration [Odo] in the recovered refrigerant gas. The correlation between the outside air temperature T and the THT concentration [Odo] in the recovered refrigerant gas is thought to represent the vapor pressure of THT at a certain temperature and a certain refrigeration oil mixing ratio. Therefore, based on the Clausius-Clapeyron equation, which shows the relationship between temperature and vapor pressure, the relationship between the outside air temperature T and the THT concentration [Odo] in the recovered refrigerant gas was formulated as shown in Equation 13 below.

[0097]

[0098]

[0099] As shown in Figure 3, the THT concentration [Odo] in the recovered refrigerant gas decreased as the outside air temperature T decreased. This is thought to be because as the outside air temperature T decreased, the temperature of the refrigerant gas decreased, which reduced the vapor pressure of THT and increased the amount of THT dissolved in the refrigerating machine oil.

[0100] As described above, it was confirmed that the lower the outside air temperature T in the installation environment, the smaller the amount of THT circulating through the refrigerant circuit together with propane, and that even when the refrigerant is released from the refrigeration cycle device, it becomes more difficult to detect the refrigerant by olfactory sense.

[0101] Note that, although the above evaluation was performed to determine the effect of the outside air temperature T on the amount of sulfur-based odorant dissolved in refrigerating machine oil when THT was used, it is believed that similar results would be obtained when a sulfur-based odorant other than THT was used. Sulfur-based odorants have polarity due to the presence of sulfur atoms, and like THT, they are easily dissolved in refrigerating machine oil, causing a drop in vapor pressure due to the influence of the refrigerating machine oil. For this reason, it is believed that the lower the outside air temperature T, the lower the vapor pressure of the sulfur-based odorant, and the greater the amount of sulfur-based odorant dissolved in refrigerating machine oil. Furthermore, when a refrigerating machine oil other than PAG is used, the amount of dissolution decreases because it is not as highly polar as PAG, but similarly, it is believed that the lower the temperature, the less the amount of sulfur-based odorant circulating.

[0102] (Evaluation Test 2) Mass Fraction M of Refrigerant to Refrigerating Machine Oil ｒｅｆ / (Mｒｅｆ +M ｏｉｌ In order to evaluate the influence of the sulfur-based odorant circulating in the refrigerant circuit together with the refrigerant, a refrigerant gas containing a refrigerant, a sulfur-based odorant, and a refrigerating machine oil was prepared under the conditions shown in Table 4.

[0103]

[0104] The refrigerant gas was sealed in a test container, stirred by shaking, and then allowed to stand at 25°C. After 24 hours of standing, the refrigerant gas was collected in a Tedlar bag (1-2711-05, manufactured by AS ONE Corporation). The THT concentration in the collected refrigerant gas was analyzed using a gas chromatograph mass spectrometer (JMS-K9, manufactured by JEOL Ltd.).

[0105] Temperature of the test container (outside air temperature T in the installation environment), amount of refrigerant enclosed M ｒｅｆ , refrigerant oil filling amount M ｏｉｌ , the mass fraction M of the refrigerant relative to the refrigerating machine oil ｒｅｆ / (M ｒｅｆ +M ｏｉｌ ), and the concentration of THT in the recovered refrigerant gas [Odo] are shown in Table 5, and the mass fraction M of the refrigerant to the refrigerating machine oil ｒｅｆ / (M ｒｅｆ +M ｏｉｌ 4 shows the relationship between the mass fraction M of the refrigerant relative to the refrigerating machine oil and the THT concentration [Odo] in the recovered refrigerant gas. ｒｅｆ / (M ｒｅｆ +M ｏｉｌ A proportional relationship was obtained between the temperature of the outside air (T) and the concentration of THT in the recovered refrigerant gas [Odo], as shown in the following formula 14. This indicates that, under the conditions of constant outside air temperature T and constant amount of THT charged, when the amount of refrigerating machine oil charged decreases, the amount of THT dissolved in the refrigerating machine oil and present in the liquid phase decreases, and the amount of THT in the gas phase increases.

[0106]

[0107]

[0108] As described above, the mass fraction M of the refrigerant to the refrigerating machine oil ｒｅｆ / (M ｒｅｆ +M ｏｉｌIt was confirmed that the more the ratio of refrigerant oil to refrigerant, the smaller the amount of THT circulating in the refrigerant circuit together with propane, and the more difficult it is to detect the refrigerant by olfactory sense even when the refrigerant is released from the refrigeration cycle device.

[0109] (Evaluation Test 3) In order to evaluate the influence of the initial concentration of the sulfur-based odorant in the refrigerant on the concentration of the sulfur-based odorant circulating through the refrigerant circuit together with the refrigerant, a commercially available household room air conditioner having a refrigerant circuit (manufactured by Mitsubishi Electric Corporation, indoor unit model number MSZ-RW35VG-E1 / outdoor unit model number MUZ-RW35VGHZ-E1) was used, and the refrigerant gas released from the refrigerant circuit was collected. The refrigerant gas to be sealed in the refrigerant circuit was prepared under the conditions shown in Table 6.

[0110]

[0111] A residential room air conditioner was operated for one hour and then stopped, and refrigerant gas was released from between the evaporator 7 and the compressor 3 when the temperature of the discharge pipe 15 of the compressor 3 was 60°C, and collected in a Tedlar bag (1-2711-05, manufactured by AS ONE Corporation). The concentration of THT in the collected refrigerant gas was analyzed using a gas chromatograph mass spectrometer (JMS-K9, manufactured by JEOL Ltd.).

[0112] Concentration of THT in the refrigerant gas to be sealed [Odo] ０ The concentration of THT in the collected refrigerant gas [Odo] is shown in Table 7, and the concentration of THT in the enclosed refrigerant gas [Odo] ０ The relationship between the concentration of THT in the collected refrigerant gas [Odo] and the concentration of THT in the collected refrigerant gas [Odo] is shown in Figure 5. ０ In other words, is the initial concentration of the sulfur-based odorant in the refrigerant.

[0113] As shown in FIG. 5, the concentration of THT in the refrigerant gas [Odo] ０and the THT concentration [Odo] in the recovered refrigerant gas, a proportional relationship was obtained as shown in the following formula 15. This is because there is a proportional relationship between the amount of THT enclosed and the vapor pressure of THT in the refrigerant circuit. Since the amount of THT is very small compared to the amount of refrigerating machine oil as a solvent, Henry's law holds true, and the partial pressure of the sulfur-based odorant is proportional to the amount of sulfur-based odorant enclosed.

[0114]

[0115]

[0116] As described above, the initial concentration of the sulfur-based odorant in the refrigerant [Odo] ０ There is a proportional relationship between the initial concentration [Odo] of the sulfur-based odorant in the refrigerant circuit and the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit. ０ It was confirmed that the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit increases as the concentration [Odo] increases.

[0117] (Derivation of Equation 1) Equation 1 is derived based on Equations 13, 14, and 15 derived from the above-described (Evaluation Test 1), (Evaluation Test 2), and (Evaluation Test 3).

[0118] Equation 13 shows the dependency of the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit on the outside air temperature T, and is based on the characteristic that the sulfur-based odorant does not evaporate from the refrigerating machine oil to the gas phase as the temperature drops. Therefore, the outside air temperature T is proportional to the mass fraction M of the refrigerant to the refrigerating machine oil. ｒｅｆ / (M ｒｅｆ +M ｏｉｌ ) and the amount of sulfur-based odorant enclosed affect the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit. That is, Equation 13 is established independently of Equation 14 and Equation 15. Equation 15 is the initial concentration [Odo] of the sulfur-based odorant in the refrigerant established by Henry's law. ０ and the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit. Therefore, the initial concentration [Odo] of the sulfur-based odorant sealed inside the refrigerant circuit ０ The relationship between the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit and the outside air temperature T and the mass fraction M of the refrigerant relative to the refrigerating machine oil isｒｅｆ / (M ｒｅｆ +M ｏｉｌ ) is satisfied as long as the amount of refrigerant oil charged is small relative to the amount of sulfur-based odorant charged. In other words, Equation 14 is satisfied independently of Equation 15. From the above, Equation 13, Equation 14, and Equation 15 are each satisfied independently, and by multiplying Equation 13, Equation 14, and Equation 15, the outside air temperature T, the mass fraction M of the refrigerant relative to the refrigerant oil, ｒｅｆ / (M ｒｅｆ +M ｏｉｌ ) the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit can be predicted.

[0119] Here, Equation 13 and Equation 15 are ｒｅｆ = 10, (M ｒｅｆ +M ｏｉｌ )=20, [Odo] ０ = 640 (ppm by volume). Therefore, the concentration [Odo] of the sulfur-based odorant circulating in the refrigerant circuit can be predicted by the following formula 16. For confirmation, the comparison result between [Odo] predicted using formula 16 and [Odo] measured by experiment is shown in FIG. 6. At this time, [Odo] in formula 16 ０ The experiment was carried out under the condition of 640 mass ppm. It was confirmed that the prediction using Equation 16 could reproduce the experimental results.

[0120]

[0121] The concentration [Odo] of the sulfur-based odorant circulating through the refrigerant circuit is required to be equal to or greater than the minimum sulfur-based odorant concentration required for the refrigerant to be olfactory-detectable when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant becomes 0.2 times the lower flammability limit, and to be within a range where the odor is not too strong. Here, if the mass ppm concentration of the sulfur-based odorant required for the refrigerant to be olfactory-detectable when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant becomes 0.2 times the lower flammability limit is D, and the mass ppm concentration of the sulfur-based odorant at which the refrigerant's odor index exceeds 18, which is the upper limit of "easily detectable odors," when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant becomes 0.2 times the lower flammability limit is F, the concentration [Odo] of the sulfur-based odorant circulating through the refrigerant circuit is required to satisfy the following formula 17.

[0122]

[0123] Note that D and F shown in Equation 17 are expressed by Equation 3 and Equation 4, respectively. The odor index is a numerical representation of the level of odor using the human sense of smell, and is the value obtained by multiplying the common logarithm of the odor concentration of an odor component (the concentration of an odor component when diluted with air until the odor is no longer detectable by the human sense of smell) by 10. The odor index has a relationship with odor intensity in the 6-level odor intensity rating system, as shown in Table 8.

[0124] In order to recognize a refrigerant by olfaction, it is necessary to recognize the presence of a sulfur-based odorant contained in the refrigerant. That is, the odor intensity of the refrigerant is preferably 2 (a weak odor that can be identified), and more preferably 3 (an odor that can be easily detected), and is also required to be within a range where the odor is not too strong. That is, the odor intensity of the refrigerant must be less than 5 (a strong odor), and it is desirable that the odor intensity of the refrigerant be within the range of 3 (an odor that can be easily detected). Therefore, in Equation 17, the upper limit is set to F, which is the mass ppm concentration of the sulfur-based odorant when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant becomes 0.2 times the lower flammability limit concentration, and the odor index of the refrigerant exceeds 18, which is the upper limit of "an odor that can be easily detected."

[0125] From Equation 16 and Equation 17, the initial concentration of the sulfur-based odorant filled in the refrigerant circuit [Odo] ０ is expressed by the following Equation 18.

[0126]

[0127] By modifying the above formula 18, formula 1 can be derived.

[0128] <Equation 7> Next, in order to explain Equation 7, (Evaluation Test 4) will be explained.

[0129] (Evaluation Test 4) In order to evaluate the amount of odorant reduction due to long-term operation of a refrigeration cycle device, a commercially available household room air conditioner having a refrigerant circuit (manufactured by Mitsubishi Electric Corporation, indoor unit model number MSZ-RW35VG-E1 / outdoor unit model number MUZ-RW35VGHZ-E1) was used, and refrigerant gas released from the refrigerant circuit was recovered. Two types of refrigerant gas were prepared under the conditions shown in Table 9 to be filled into the refrigerant circuit.

[0130]

[0131] A residential room air conditioner was operated for one hour and then stopped, and refrigerant gas was released from between the evaporator 7 and the compressor 3 when the temperature of the discharge pipe 15 of the compressor 3 was 60°C, and collected in a Tedlar bag (1-2711-05, manufactured by AS ONE Corporation). The concentration of THT in the collected refrigerant gas was analyzed using a gas chromatograph mass spectrometer (JMS-K9, manufactured by JEOL Ltd.).

[0132] Figure 7 shows the change over time in the THT concentration [Odo] in the recovered refrigerant gas when the average discharge temperature Td is 102°C and when the average discharge temperature is 66°C. As shown in Figure 7, the higher the average discharge temperature Td and the longer the time that has passed, the lower the THT concentration [Odo] in the recovered refrigerant gas. This is because the longer the time exposed to high temperatures, the more easily THT deteriorates and decomposes.

[0133] The time change of [Odo] shown in Figure 7 was approximated by an exponential function, and the relationship between the average discharge temperature Td and the decreasing tendency of the THT concentration [Odo] in the recovered refrigerant gas was formulated as shown in the following Equation 17 based on the Arrhenius equation. Here, t in Equation 19 is the time until the THT concentration [Odo] reaches a certain value. Also, [Odo] shown in Equation 19 ０ｈｒ is A shown in Equation 1.

[0134]

[0135] Here, we will explain how to derive Equation 19. As shown in Figure 7, the decreasing trend of [Odo] can be approximated by an exponential function, which shows that this reaction is a first-order reaction that depends on [Odo]. In the case of a first-order reaction, [Odo] is proportional to [Odo]. ０ｈｒ , reaction rate constant k, and time t, it is expressed by the following Equation 20.

[0136]

[0137] The reaction rate constant k is calculated by the Arrhenius equation using the frequency factor k ａ , the activation energy of the reaction E ａ , gas constant R, and temperature T, the following equation 21 is expressed: Equation 21 can be converted to Equation 22 by taking the natural logarithm of both sides.

[0138]

[0139]

[0140] When the time it takes for a chemical reaction to change from an initial value to a certain value is τ, the reaction rate constant k is proportional to 1 / τ, and therefore Equation 22 can be expressed as Equation 23 below.

[0141]

[0142] Here, for the two exponential functions shown in FIG. 7, the time until [Odo] reaches 0.3 mass ppm is defined as τ ０．３質量ｐｐｍ From Equation 23, when the average discharge temperature is 102°C and 66°C, τ ０．３質量ｐｐｍ are calculated as 15270 hr and 122839 hr, respectively. ０．３質量ｐｐｍThe relationship between the natural logarithm of THT and the reciprocal of the average value of the discharge temperature is shown in Figure 8. From the equation obtained by linear approximation, the decrease in THT is ａ / R = 7369. ａ From / R and the exponential function in Figure 7, the frequency factor k ａ is calculated as 171702.

[0143] According to the above-derived formula 19, the average discharge temperature T ｄ and the amount of sulfur-based odorant that decreases depending on the operating time t of the refrigeration cycle device. As described above, the initial concentration of the sulfur-based odorant expressed by Equation 19 is required to be equal to or greater than the minimum concentration of the sulfur-based odorant required to allow the refrigerant to be recognized by the sense of smell when the refrigerant diffuses in the air and the concentration of hydrocarbons contained in the refrigerant becomes 0.2 times the lower flammability limit concentration, and to be within a range in which the odor is not too strong. Therefore, Equation 7 can be derived from Equation 17 and Equation 19.

[0144] Although the present disclosure has been described above based on each embodiment, the present disclosure is not limited to each embodiment. Furthermore, appropriate combinations, modifications, omissions, etc. of each embodiment are also included within the scope of the technical idea of ​​the present disclosure.

[0145] REFERENCE SIGNS LIST 1 outdoor unit 2 indoor unit 3 compressor 4 condenser 5 outdoor blower 6 expansion valve 7 evaporator 8 indoor blower 9 liquid pipe 10 gas pipe 11 shell 12 compression mechanism 13 electric motor 14 suction pipe 15 discharge pipe 16 accumulator 17 rolling piston 18 cylinder 19 cylinder chamber 20 upper bearing 21 discharge hole 22 muffler space 23 discharge muffler 24 discharge hole 25 electric motor rotor 26 electric motor stator 27 oil reservoir 28 drive shaft 100 refrigerant circuit

Claims

1. A refrigerant circuit including a compressor is provided, a refrigerant is sealed inside the refrigerant circuit, the refrigerant includes hydrocarbons having 1 to 4 carbon atoms and a sulfur-based odorant, the compressor is filled with refrigerating machine oil, and an initial concentration of the sulfur-based odorant in the refrigerant is [Odo] ０ (mass ppm), the outside air temperature in the installation environment is T (K), and the amount of the refrigerant charged is M ｒｅｆ (g) The amount of the refrigerating machine oil filled is M ｏｉｌ (g) The molecular weight of the hydrocarbon is MW ｒｅｆ The molecular weight of the sulfur-based odorant is MW ｏｄｏ The olfactory threshold of the sulfur-based odorant is [Odo] ｍｉｎ (ppm by volume), the lower flammable limit concentration of the hydrocarbon is [Ref] ＬＦＬ (volume %), an initial concentration of the sulfur-based odorant in the refrigerant satisfies the following formula 1, A given by formula 1 satisfies formula 2, D satisfies formula 3, F satisfies formula 4, C given by formula 3 satisfies formula 5, and E given by formula 4 satisfies formula 6.

2. The average discharge temperature of the refrigerating machine oil is T ｄ (K) When an operating time is t (hr), an initial concentration of the sulfur-based odorant in the refrigerant satisfies the following formula 7, and G given by formula 7 satisfies formula 8. The refrigeration cycle device according to claim 1, 3. The refrigeration cycle device according to claim 2, wherein the hydrocarbon is propane, the sulfur-based odorant is tetrahydrothiophene, the refrigerating machine oil is polyalkylene glycol, and an initial concentration of the sulfur-based odorant in the refrigerant satisfies the following mathematical formula 9.

4. The refrigeration cycle device according to claim 3, wherein the hydrocarbon is propane, the sulfur-based odorant is tetrahydrothiophene, the refrigerating machine oil is polyalkylene glycol, and an initial concentration of the sulfur-based odorant in the refrigerant satisfies the following mathematical formula 10.

5. The refrigeration cycle device according to claim 2, wherein an initial concentration of the sulfur-based odorant in the refrigerant satisfies the following formula 11.

6. The refrigeration cycle device according to claim 2, wherein an initial concentration of the sulfur-based odorant in the refrigerant satisfies the following formula 12.

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