JP2010159310A - Stabilizer for working medium, working medium composition, and heat exchange method - Google Patents

Abstract

A stabilizer capable of stabilizing a working medium containing trifluoroiodomethane compressed in the presence of lubricating oil in a compressor, a working medium composition containing the stabilizer, and the stabilizer Provision of heat exchange method used.
A stabilizer for a working medium containing trifluoroiodomethane that is compressed in the presence of a lubricating oil by a compressor, the hydrocarbon having a nitro group as an active ingredient. A working medium composition comprising a working medium containing trifluoroiodomethane and the stabilizer. A heat exchange method comprising a step of compressing a working medium containing trifluoroiodomethane in a compressor in the presence of a lubricating oil and the stabilizer.
[Selection figure] None

Description

  The present invention relates to a stabilizer for a working medium containing trifluoroiodomethane, which has little influence on the ozone layer and little influence on global warming, a working medium composition containing the stabilizer and the working medium, and the The present invention relates to a heat exchange method using a working medium composition.

Conventionally, chlorofluorocarbons (CFCs) such as chlorotrifluoromethane and dichlorodifluoromethane, and hydrochlorofluorocarbons (HCFCs) such as chlorodifluoroethane are used as working media (for example, refrigeration air conditioners, automotive air conditioners). Refrigerants used in cooling systems, working fluids used in waste heat recovery power generation, working media used in latent heat transport devices such as heat pipes, secondary cooling media, etc.), foaming agents, various precision parts Are used in various fields such as cleaning solvents, cleaning solvents, solvents, propellants and the like.
However, it has been pointed out that CFCs and HCFCs, when released into the atmosphere, destroy the ozone layer in the stratosphere, resulting in a serious adverse impact on the earth's ecosystem including humans. It has become. Therefore, instead of CFCs and HCFCs, hydrofluorocarbons (HFCs) such as difluoromethane, tetrafluoroethane, and pentafluoroethane that do not contain the risk of ozone layer destruction and that do not contain chlorine are now preferred. It has come to be.
However, although it is HFCs without the danger of destroying the ozone layer, it has been pointed out that it may cause global warming when released into the atmosphere. In particular, 1,1,1,2-tetrafluoroethane (HFC-134a), which is generally used as a refrigerant for automobile air conditioning equipment, has a large global warming potential of 1300 (100-year value). For this reason, there is an urgent need to develop a compound with a low possibility of ozone layer destruction and a low possibility of global warming.
Examples of media that replace HFC-134a include carbon dioxide (CO ₂ ) that exists in nature, and a global warming potential of 120 (100-year value), which is about 1/10 that of HFC-134a, which is as low as 1,1- Difluoroethane (HFC-152a) has been studied.
However, since carbon dioxide has extremely high equipment pressure, many problems to be solved have been pointed out for application to working media such as automotive air conditioning equipment. Moreover, HFC-152a has a combustion range, and the subject for ensuring safety | security is pointed out.

In addition, iodocarbons such as trifluoroiodomethane have attracted attention as one of compounds that have little influence on the ozone layer and little influence on global warming. For example, trifluoroiodomethane has the same equipment pressure as HFC-134a, has little influence on the ozone layer, and has a relatively low global warming potential.
Therefore, it has been proposed to use iodocarbons as a working medium. For example, in Patent Document 1, trifluoroiodomethane and trifluoroiodomethane and propane, propylene, cyclopropane, dimethyl ether, methylmethyleneamine, difluoromethane, A mixed medium of 1,1,1-trifluoroethane, 1,1-difluoroethane, and fluoroethane is proposed. In Patent Document 2, a mixed working medium of trifluoroiodomethane, difluoromethane, and pentafluoroethane is proposed. ing. In general formula _{C a H b Br c Cl d} F e I f N g O h mixed medium containing fluoro Io de carbon represented by is proposed in Patent Document 3, trifluoroiodomethane in Patent Document 4 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane mixed media have been proposed.
However, since the bond energy between iodine atoms and carbon atoms is extremely small compared to the bond energy between other halogen atoms and carbon atoms, the bonds between iodine atoms and carbon atoms are easily broken and decomposed. There is a problem that is easy to do.
In particular, when iodocarbons are used as a working medium, the decomposition of the iodocarbons may cause deterioration in the performance of equipment such as refrigeration air conditioners and automotive air conditioners.
That is, a refrigerant used in a working medium, such as a refrigeration air conditioner or an automotive air conditioner, generally compresses the working medium into a high-temperature and high-pressure gas, and condenses the working medium compressed by the compressor. Circulates in an apparatus equipped with a condenser for forming a low-temperature liquid, expansion means for adiabatically expanding the working medium condensed by the condenser, a heat exchanger for exchanging cold heat of the working medium expanded by the expansion means, and the like. . At this time, since it is compressed by the compressor in the presence of a lubricant and brought into a high temperature and high pressure state, trifluoroiodomethane is likely to be decomposed. In addition to oxidation of trifluoroiodomethane, oxidation of lubricating oil is likely to occur.
Decomposition of trifluoroiodomethane and oxidation of lubricating oil may cause deterioration in the performance of equipment such as refrigeration air conditioners and automotive air conditioners. In addition, the products generated by these decomposition and oxidation may cause corrosion of the metal material constituting the device and blockage of the expansion device.

Patent Documents 5 to 6 propose blending a radical chain inhibitor in order to prevent decomposition of trifluoroiodomethane. In these patent documents, as specific radical chain inhibitors, it is described that a compound having a hindered phenol structure, an arylamine structure, a hindered piperidine structure, a thioether structure, or a phosphite structure can be used alone or in combination. Yes. Patent Document 7 proposes blending isoprenes, propadiene, terpenes and the like for stabilization of iodocarbons. Patent Document 8 proposes a phenol compound or a combination of a phenol compound and an epoxy compound as a stabilizer for trifluoroiodomethane.
However, with the compounds used in these patent documents, it is difficult to sufficiently prevent the decomposition of trifluoroiodomethane.
On the other hand, Patent Document 9 proposes a foaming agent for a synthetic resin composed of an iodocarbon having 1 to 2 carbon atoms and a low-boiling point aliphatic hydrocarbon having a boiling point of 70 ° C. or less. It is described that nitro compounds, aromatic hydrocarbons, aliphatic unsaturated hydrocarbons, epoxy compounds, phenol compounds, and the like can be blended as decomposition inhibitors. However, Patent Document 9 does not describe a specific effect of the decomposition inhibitor. Further, since Patent Document 9 relates to a synthetic resin foaming agent, particularly polyurethane or polyisocyanurate foaming agent, it is not possible to analogize the effect when the decomposition inhibitor is used in a working medium such as a refrigeration air conditioner. Is possible.
JP-A-4-323294 (Claims) JP-A-8-277389 (Claims) US Pat. No. 5,611,210 (Claims) US Pat. No. 6,270,689 (Claims) JP-A-9-59612 (Claims) JP-A-9-111231 (Claims) International Publication No. 2006/069362 Pamphlet (Claims) US Patent Application Publication No. 2006/0033072 (Claims) JP 2000-191816 A (Embodiment of the Invention)

  The present invention has been made in view of the above circumstances, and includes a stabilizer capable of stabilizing a working medium containing trifluoroiodomethane that is compressed in the presence of lubricating oil by a compressor, and the stabilizer. Provided is a working medium composition to be contained, and a heat exchange method using the stabilizer.

The present invention has the following aspects.
[1] A working medium stabilizer containing trifluoroiodomethane compressed in the presence of lubricating oil in a compressor,
Stabilizers containing hydrocarbons having nitro groups as active ingredients.
[2] The stabilizer according to [1], wherein the hydrocarbon having a nitro group is a nitroalkane and / or an aromatic hydrocarbon having a nitro group.
[3] The stabilizer according to [1] or [2], further comprising an epoxy compound.
[4] A working medium composition containing a working medium containing trifluoroiodomethane and the stabilizer according to any one of [1] to [3].
[5] Heat exchange including a step of compressing the working medium containing trifluoroiodomethane in the compressor in the presence of the lubricating oil and the stabilizer according to any one of [1] to [3]. Method.

According to the stabilizer of this invention, the working medium containing the trifluoroiodomethane compressed in presence of lubricating oil with a compressor can be stabilized. Moreover, the oxidation of the lubricating oil when the working medium is compressed can be suppressed. Accordingly, it is possible to prevent deterioration in the performance of equipment such as a refrigeration air conditioner and an automotive air conditioner in which these working media and lubricating oil are used, and corrosion of a metal material constituting the equipment.
Moreover, the working medium composition and heat exchange method of the present invention are excellent in the stability of the working medium when compressed in the presence of lubricating oil by a compressor. Moreover, since trifluoroiodomethane is included as a working medium, there is little influence on an ozone layer and the influence on global warming is small. Therefore, it is suitable as a refrigerant for cooling systems such as refrigeration air conditioners and automotive air conditioners, working fluid such as waste heat recovery power generation, working medium for latent heat transport devices such as heat pipes, secondary cooling medium, and the like.

<Stabilizer>
The stabilizer of the present invention comprises a hydrocarbon having a nitro group (hereinafter sometimes referred to as a nitro group-containing hydrocarbon) as an active ingredient.
Here, in the present specification and claims, “hydrocarbons having a nitro group” are compounds having a hydrocarbon having a nitro group as a basic skeleton, in addition to hydrocarbons having a nitro group, nitro groups. A compound in which some or all of the hydrogen atoms of a hydrocarbon having a group are substituted with a substituent other than a nitro group is included.
The “hydrocarbon” in the nitro group-containing hydrocarbons may be a saturated hydrocarbon or an unsaturated hydrocarbon. Further, it may be an aromatic hydrocarbon or a hydrocarbon having no aromaticity (aliphatic hydrocarbon).
Examples of the “substituent other than the nitro group” that the nitro group-containing hydrocarbons may have include a hydroxyl group, an alkoxy group, and an alkylcarbonyl group.

As the nitro group-containing hydrocarbons, known or well-known compounds are exemplified, but aromatic hydrocarbons having a nitroalkane and / or a nitro group are preferable.
The nitroalkane is preferably a nitroalkane having 1 to 3 carbon atoms, and specific examples thereof include nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane.
As the aromatic hydrocarbon having a nitro group, a compound in which 1 to 3 nitro groups are bonded to a hydrocarbon having a benzene ring is preferable. Examples of the hydrocarbon having a benzene ring include benzene and alkylbenzene. The compound may or may not have a substituent other than a nitro group. Specific examples of the compound include nitrobenzene, o-, m- or p-dinitrobenzene, trinitrobenzene, o-, m- or p-nitrotoluene, o-, m- or p-ethylnitrobenzene, 2,3- 2,4-, 2,5-, 2,6-, 3,4- or 3,5-dimethylnitrobenzene, o-, m- or p-nitroacetophenone, o-, m- or p-nitrophenol, o-, m- or p-nitroanisole and the like can be mentioned.
Any of these may be used alone or in combination of two or more.

The stabilizer of the present invention preferably further contains an epoxy compound. Thereby, decomposition | disassembly of trifluoride methane can be prevented more effectively, and the stability of a working medium further improves.
Examples of the epoxy compound include known or well-known compounds, such as ethylene oxide, 1,2-butylene oxide, propylene oxide, styrene oxide, cyclohexene oxide, glycidol, epichlorohydrin, glycidyl methacrylate, phenyl glycidyl ether, allyl glycidyl ether. , Monoepoxy compounds such as methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, diepoxybutane, vinylcyclohexene dioxide, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, glycerin polyglycidyl ether, trimethylol Examples thereof include polyepoxy compounds such as propane toglycidyl ether.
Any of these may be used alone or in combination of two or more.
In the stabilizer of the present invention, the content of the epoxy compound is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the nitro group-containing hydrocarbons. .

The stabilizer of the present invention includes, in addition to hydrocarbons and epoxy compounds having a nitro group, as other stabilizers such as phenols, amines, α-methylstyrene, p-isopropenyltoluene and isoprenes. Further, hydrocarbons such as propadiene and terpene may be contained.
Examples of the phenols include phenols containing various substituents such as alkyl groups, alkenyl groups, alkoxy groups, carboxyl groups, carbonyl groups, and halogens in addition to the hydroxyl groups. For example, 2,6-di-t-butyl-p-cresol, o-cresol, m-cresol, p-cresol, thymol, pt-butylphenol, o-methoxyphenol, m-methoxyphenol, p-methoxyphenol, eugenol Monohydric phenols such as isoeugenol, butylhydroxyanisole, phenol and xylenol, or divalent phenols such as t-butylcatechol, 2,5-di-t-aminohydroquinone and 2,5-di-t-butylhydroquinone Etc. are exemplified.
Examples of amines include pentylamine, hexylamine, diisopropylamine, diisobutylamine, di-n-propylamine, diallylamine, triethylamine, N-methylaniline, pyridine, morpholine, N-methylmorpholine, triallylamine, allylamine, α-methylbenzyl. Amine, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, dibutylamine, tributylamine, diventylamine, triventylamine, 2-ethylhexylamine, Aniline, N, N-dimethylaniline, N, N-diethyleniline, ethylenediamine, propylenediamine, diethylenetriamine, tetrae Renpentamin, benzylamine, dibenzylamine, diphenylamine, Gillet chill hydroxylamine and the like.
Any of these may be used alone or in combination of two or more.
In the stabilizer of the present invention, the content of the other stabilizer is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass of the total amount of the nitro group-containing hydrocarbons and the epoxy compound, 10 mass parts is more preferable.

Examples of the method of using the stabilizer of the present invention, that is, the method of stabilizing a working medium containing trifluoroiodomethane using the stabilizer of the present invention include, for example, trifluoroiodide in the presence of lubricating oil in a compressor. The method of performing the process which compresses the working medium containing methane in presence of the stabilizer of the said this invention is mentioned.
In such a method, the stabilizer may be added in advance to one or both of the working medium and the lubricant, or may be added alone in the compressor.
At this time, although the usage-amount of a stabilizer is not specifically limited, 0.001-20 mass parts is preferable with respect to trifluoroiodomethane (100 mass parts), 0.01-10 mass parts is more preferable, 0.05-5 mass parts is more preferable. When it is at least the lower limit of the above range, the effects of the present invention are sufficiently obtained, and when it is at most the upper limit, it is preferable in terms of working medium characteristics, refrigerant performance and the like.
The working medium and the lubricant will be described in detail in the section of the working medium composition of the present invention below.

<Working medium composition>
The working medium composition of the present invention contains a working medium containing trifluoroiodomethane and the stabilizer of the present invention.

In the working medium, the proportion of trifluoroiodomethane is, for example, preferably 25 to 100% by mass, and more preferably 25 to 75% by mass.
The working medium may contain a compound conventionally known as a working medium in addition to trifluoroiodomethane. Examples of such compounds include halogenated compounds such as iodocarbons other than trifluoroiodomethane, hydrofluorocarbons (HFCs), unsaturated HFCs, cyclic HFCs, and cyclic unsaturated HFCs, carbon dioxide, and hydrocarbons. Etc.
Examples of the iodocarbons other than trifluoroiodomethane include pentafluoroiodoethane and difluoroiodomethane.
Examples of HFCs include difluoromethane, difluoroethane, trifluoroethane, tetrafluoroethane, pentafluoroethane and the like.
Examples of unsaturated HFCs include 3,3,3-trifluoropropylene, 1,3,3,3-tetrafluoropropylene, 2,3,3,3-tetrafluoropropylene, 1,2,3,3- Examples thereof include tetrafluoropropylene, 1,1,3,3,3-pentafluoropropylene, 1,2,3,3,3-pentafluoropropylene and the like.
Examples of hydrocarbons include propane, butane, isobutane, pentane and the like.
Any of these may be used alone or in combination of two or more.

  In the working medium composition of the present invention, the content of the stabilizer is not particularly limited, but is preferably 0.001 to 20 parts by mass with respect to trifluoroiodomethane (100 parts by mass), and 0.01 to 10 mass parts is more preferable, and 0.05-5 mass parts is further more preferable. When it is at least the lower limit of the above range, the effects of the present invention are sufficiently obtained, and when it is at most the upper limit, it is preferable from the viewpoint of working medium characteristics and the like.

The working medium composition of the present invention may further contain a lubricating oil.
As the lubricating oil, generally known or well-known compounds used in a compressor for compressing a working medium can be used.
In the present invention, the lubricating oil preferably has a kinematic viscosity at 100 ° C. of ^{2 to} 150 mm ² / s (cSt), and more preferably 4 to 100 mm ² / s. Further, preferably a kinematic viscosity at 40 ° C. is 2~300mm ² / s, more preferably 4~150mm ² / s.
Here, in the present invention, the kinematic viscosity of the lubricating oil is a value measured by a kinematic viscosity test method defined in JIS K2283.

Specific examples of the lubricating oil include oxygen-containing synthetic oils such as ester-based lubricating oils, ether-based lubricating oils, and polyglycol oils, fluorine-based lubricating oils, mineral oils, and hydrocarbon-based synthetic oils.
Examples of ester-based lubricating oils include dibasic acid ester oils, polyol ester oils, complex ester oils, and polyol carbonate oils.
Dibasic acid esters include dibasic acids having 5 to 10 carbon atoms such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, methanol, ethanol, propanol, butanol, pentanol, hexanol, Esters with a monohydric alcohol having 1 to 15 carbon atoms having a linear or branched alkyl group such as heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol and the like are preferable. Specific examples include ditridecyl glutarate, di (2-ethylhexyl) adipate, diisodecyl adipate, ditridecyl adipate, di (3-ethylhexyl) sebacate and the like.

The polyol ester oil is preferably an ester of a polyol having 3 to 20 diols or hydroxyl groups and a fatty acid having 6 to 20 carbon atoms.
Here, as the diol, ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,2-butanediol, 1,5-pentadiol, neopentyl glycol, 1,7-heptane Diol, 1,12-dodecanediol, etc. are mentioned.
Examples of the polyol having 3 to 20 hydroxyl groups include trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, glycerin, sorbitol, sorbitan, and sorbitol glycerin condensate.
Examples of fatty acids having 6 to 20 carbon atoms include straight-chain or branched fatty acids such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, eicosanoic acid, oleic acid, and α carbon atoms There are so-called neoacids in which is a fourth grade.
The polyol ester oil may have a free hydroxyl group.
Polyol ester oils include esters of hindered alcohols such as neopentyl glycol, trimethylol ethane, trimethylol propane, trimethylol butane, pentaerythritol, trimethylol propane tripelargonate, pentaerythritol 2-ethylhexanoate. And pentaerythritol tetrapelargonate are preferred.

  The complex ester oil is an ester of a fatty acid and a dibasic acid, and a monohydric alcohol and a polyol. The above-mentioned fatty acids, dibasic acid, monohydric alcohol and polyol can be used in the same manner.

The polyol carbonate oil is an ester of carbonic acid and polyol. As a polyol here, the polyglycol which homopolymerized or copolymerized diol, the polyol similar to what was illustrated by description of the above-mentioned polyol ester, what added polyglycol to the polyol, etc. can be used.
As diol, the thing similar to what was illustrated by description of the above-mentioned polyol ester can be used. As the polyglycol, polyalkylene glycol, an ether compound thereof, a modified compound thereof and the like are preferably used.
Examples of the polyalkylene glycol include those obtained by a method in which an alkylene oxide having 2 to 4 carbon atoms such as ethylene oxide or propylene oxide is polymerized using water or an alkali hydroxide as an initiator. Moreover, what etherified the hydroxyl group of polyalkylene glycol can also be used. The oxyalkylene units in the polyalkylene glycol may be the same in one molecule, and two or more oxyalkylene units may be included. It is preferable that at least an oxypropylene unit is contained in one molecule.

  The polyglycol oil is preferably a polyalkylene glycol oil based on polyalkylene glycol. Examples of the polyalkylene glycol include hydroxy group-initiated polyalkylene glycols such as compounds in which an alkylene oxide having 2 to 4 carbon atoms is added to a monovalent or polyhydric alcohol such as methanol, butanol, pentaerythritol, and glycerol. . In addition, a hydroxy group-initiated polyalkylene glycol whose end is capped with an alkyl group such as a methyl group is also exemplified.

Illustrative examples of fluorine-based lubricating oils include mineral oils, poly α-olefins, compounds obtained by replacing hydrogen atoms in synthetic oils such as alkylbenzene and alkylnaphthalene with fluorine atoms, perfluoropolyether oils, and fluorinated silicone oils. Is done.
As mineral oil, for example, a lubricating oil fraction obtained by subjecting crude oil to atmospheric distillation or reduced pressure distillation is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, clay. Paraffinic mineral oils, naphthenic mineral oils, and the like purified by appropriately combining purification treatments such as treatment can be used.
As the hydrocarbon-based synthetic oil, for example, poly-α-olefin, alkylbenzene, and alkylnaphthalene can be used.

These various lubricating oils can be used alone or in combination of two or more.
In the present invention, considering compatibility with the working medium, mineral oil and / or polyglycol oil are preferable, and naphthenic mineral oil and / or polyalkylene glycol oil are more preferable. Among them, polyalkylene glycol oil is preferable because a remarkable antioxidant effect is obtained by the stabilizer of the present invention.
In the working medium composition of the present invention, the content of the lubricating oil is not particularly limited and varies depending on the application, the type of the compressor, etc., but is usually 10 to 100 mass with respect to the working medium (100 parts by mass). Part is preferable, and 20-50 mass parts is more preferable.

  In addition to the above, the working medium composition of the present invention may contain any additive as long as the effects of the present invention are not impaired. Examples of the additive include additives such as an oxidation resistance improver, a heat resistance improver, a metal deactivator, and a load bearing additive, an antifoaming agent, an extreme pressure agent, and a rust preventive agent that are used in lubricating oils. And various additives such as a viscosity index improver and a pour point depressant.

<Heat exchange method>
The heat exchange method of the present invention includes a step of compressing a working medium containing trifluoroiodomethane in a compressor in the presence of a lubricating oil and the stabilizer of the present invention.
The heat exchange method of the present invention can be applied to, for example, a heat exchange cycle system whose schematic configuration is shown in FIG.
A heat exchange cycle system 20 shown in FIG. 1 compresses a working medium vapor (working medium vapor) G to convert the working medium vapor G into a high-temperature and high-pressure working medium vapor H, and discharges it from the compressor 21. The condenser 22 that cools the liquefied working medium vapor H and liquefies it into a low temperature and high pressure working medium I, and the expansion valve that expands the working medium I discharged from the condenser 22 to form a low temperature and low pressure working medium J 23, a heat exchanger (evaporator) 24 for exchanging the cold heat of the working medium J discharged from the expansion valve 23 and using the working medium as a high-temperature and low-pressure steam (working medium steam G), and a heat exchanger 24 The system schematically includes a pump 25 that supplies a heat source fluid K and a pump 26 that supplies a load fluid L to the condenser 22.

In the heat exchange cycle system 20, the following steps (i) to (iv) are repeated.
(I) A step of compressing the working medium vapor G discharged from the heat exchanger 24 in the presence of lubricating oil in the compressor 21 to obtain a high-temperature and high-pressure working medium vapor H.
(Ii) A step of cooling the working medium vapor H discharged from the compressor 21 with the load fluid L in the condenser 22 and liquefying it to obtain a low temperature and high pressure working medium I. At this time, the load fluid L is heated to become a fluid L ′ and is discharged from the condenser 22.
(Iii) A step of expanding the working medium I discharged from the condenser 22 by the expansion valve 23 to obtain a low temperature / low pressure working medium J.
(Iv) A step of heating the working medium J discharged from the expansion valve 23 by the heat source fluid K in the heat exchanger 24 to obtain a high temperature / low pressure working medium vapor G. At this time, the heat source fluid K is cooled to become a fluid K ′ and is discharged from the heat exchanger 24.

In the step (i), the working medium vapor G is converted into high-temperature and high-pressure vapor (for example, vapor at a temperature of 120 to 170 ° C. and a pressure of about 1 to 2 MPa) by compression.
In the present invention, when the working medium vapor G of (i) is compressed by the compressor 21, the working medium can be stabilized by the presence of the stabilizer of the present invention together with the lubricating oil, For example, decomposition of trifluoroiodomethane can be suppressed. In addition, oxidation of the lubricating oil can be prevented.
The stabilizer may be added in advance to one or both of the working medium and the lubricant, or may be added alone in the compressor.
Although the usage-amount of a stabilizer is not specifically limited, 0.001-20 mass parts is preferable with respect to trifluoroiodomethane (100 mass parts), 0.01-10 mass parts is more preferable, 0.05 -5 mass parts is more preferable. When it is at least the lower limit of the above range, the effects of the present invention are sufficiently obtained, and when it is at most the upper limit, it is preferable in terms of working medium characteristics, refrigerant performance and the like.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
The measurement methods used in the following examples and comparative examples are shown below.
[Purity of trifluoroiodomethane]
The purity and acid content of trifluoroiodomethane were measured in accordance with the provisions of “4.4 Purity” and “4.6 Acid Content” of JIS K1560, respectively.
[Kinematic viscosity and total acid value of lubricating oil]
The kinematic viscosity and the total acid value of the lubricating oil are respectively defined by the measurement methods defined in JIS K2211 (refrigeration machine oil), that is, JIS K2283 (crude oil and petroleum products-kinematic viscosity test method and viscosity index calculation method). It measured based on the kinematic viscosity test method and the total acid value test method and strong acid value test method prescribed | regulated to JISK2501 (petroleum product and lubricating oil-neutralization number test method).

[Examples 1-8, Comparative Examples 1-10]
A Pyrex (registered trademark) glass intubation tube was introduced into a stainless steel (SUS-316) pressure vessel (portable reactor, TVS-N2 type, internal volume 200 mL; pressure-resistant techno).
On the other hand, three types of metal pieces (iron, copper, and aluminum) (30 mm × 30 mm × 3 mm plate shape with a hole of 3 mm in diameter) are directly attached to the spacer made of polytetrafluoroethylene. It fixed with the SUS bolt so that it might not contact, and this was thrown into the pressure vessel.
Next, 50 g of the lubricating oil shown in Table 1 and a stabilizer are put into the pressure vessel, and then the pressure vessel is covered and completely sealed, and then the pressure vessel is cooled to −50 ° C. Thus, the lubricating oil was solidified. Next, the inside of the pressure vessel was evacuated and then filled with 50 g of trifluoroiodomethane to obtain a working medium composition.
After confirming that there was no leakage from the pressure vessel, the pressure vessel was placed in a hot air circulation type thermostat and held (aged) at 125 ° C. for 14 days.
After 14 days, the pressure vessel was taken out, and the purity and acid content of trifluoroiodomethane and the total acid value of the lubricating oil were measured by the above measuring method.
In addition, as a control (before the test), a working medium composition was prepared in the same manner as described above except that no stabilizer was added, and the working medium composition was purified in the same manner as above, and the purity and acid content of trifluoroiodomethane. And the total acid number of the lubricating oil was measured.
The results are shown in Table 2. In Table 2, it shows that trifluoroiodomethane has decomposed | disassembled, so that purity is low or the value of acid content is large. Moreover, it shows that lubricating oil is oxidizing, so that the value of total acid value is large.

The naphthenic mineral oils in Table 1 are Suniso 5GS (manufactured by Idemitsu Kosan Co., Ltd., kinematic viscosity at 100 ° C .: 8.09 mm ² / s, kinematic viscosity at 40 ° C .: 95.9 mm ² / s, pour point: − 27.5 ° C.).
In addition, polyalkylene glycol oil is a compressor oil for car air conditioners for HFC134a ND-oil 8 (manufactured by Denso Corporation).
Moreover, the compounding quantity (%) of a stabilizer is a ratio (mass%) with respect to trifluoroiodomethane (100 mass%).

Examples 1 and 3 and Comparative Examples 6 to 9 in which naphthenic mineral oil is blended as a lubricating oil and the blending amount of stabilizer (relative to trichloroiodomethane) is the same, and naphthenic mineral oil is used as a lubricating oil When Comparative Example 3 in which no stabilizer was added was compared, Examples 1 and 3 had the same or higher purity as Comparative Examples 3 and 6 to 9, and both the acid content and the total acid value were Comparative Examples. Compared with 6-9, it was greatly improved.
On the other hand, Comparative Examples 6 to 9 in which stabilizers other than nitro group-containing hydrocarbons were blended had worse acid content and total acid value than Comparative Example 3 in which no stabilizer was blended. From this result, it is presumed that the decomposition of trifluoroiodomethane and the oxidation of the lubricating oil were promoted by adding a stabilizer other than the nitro group-containing hydrocarbons.
Similarly, when naphthenic mineral oil is blended as a lubricating oil and the total blending amount of stabilizer (relative to trichloroiodomethane) is the same, Examples 2 and 4-7 are compared with Comparative Examples 1 and 2. In Examples 2, 4 to 7, all items of purity, acid content, and total acid value were significantly improved as compared with Comparative Examples 1 and 2. Of Examples 2 and 4 to 7, Examples 5 to 7 in which nitro group-containing hydrocarbons and an epoxy compound are used in combination have particularly good results for the pure content, and the pure content is almost the same as before the test. It had been.
In addition, when Example 8 in which polyalkylene glycol oil was blended as a lubricating oil was compared with Comparative Example 4, Example 8 was improved in all items of purity, acid content, and total acid value as compared with Comparative Example 4. In particular, the result of the total acid value was good.
From the above results, it was confirmed that the stabilizer containing the nitro group-containing hydrocarbons could effectively suppress the decomposition of trifluoroiodomethane and the oxidation of the lubricating oil.

  Further, when Comparative Examples 3 to 4 in which the lubricating oil was blended and the stabilizer was not blended were compared with Comparative Example 5 in which both the lubricating oil and the stabilizer were not blended, Comparative Example 3 in which the lubricating oil was blended. In -4, the pure content of trifluoroiodomethane was significantly reduced. From this result, it was found that the decomposition of trifluoroiodomethane was promoted in a system in which lubricating oil was present.

It is a schematic structure figure showing an example of a heat exchange cycle system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Heat exchange cycle system, 21 ... Compressor, 22 ... Condenser, 23 ... Expansion valve, 24 ... Heat exchanger, 25 ... Pump, 26 ... Pump

Claims (5)

A working medium stabilizer comprising trifluoroiodomethane compressed in the presence of lubricating oil in a compressor,
Stabilizers containing hydrocarbons having nitro groups as active ingredients.   The stabilizer according to claim 1, wherein the hydrocarbon having a nitro group is a nitroalkane and / or an aromatic hydrocarbon having a nitro group.   Furthermore, the stabilizer of Claim 1 or 2 containing an epoxy compound.   The working-medium composition containing the working medium containing a trifluoroiodomethane, and the stabilizer as described in any one of Claims 1-3.   The heat exchange method including the process which compresses the working medium containing a trifluoroiodomethane in presence of lubricating oil and the stabilizer as described in any one of Claims 1-3 in a compressor.

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