JP2001311088A - Freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a freezer having excellent compatibility with HFC, capable of sufficiently securing reliability of a compressor and actualizing a viscosity of refrigerating machine oil to attain a high efficiency, slightly causing formation of an organic acid by hydrolysis and thermal decomposition and controlling a generated CO2 to a level not to exert a bad influence on cooling performances. SOLUTION: In a freezing cycle constituted of a compressor 1, a condenser 2, an expansion mechanism 3, a dryer 5 and an evaporator 4 and using a hydrofluorocarbon as a refrigerant, a refrigerating machine oil 6 comprising a carbonate oil having 2-70 cSt viscosity at 40 deg.C and 1-9 cSt viscosity at 100 deg.C and containing at least one carbonate bond (-O-CO-O-) in the molecule as a base oil is used to provide the objective freezer capable of sufficiently securing reliability of a compressor and actualizing a viscosity of refrigerating machine oil to attain a high efficiency, slightly causing formation of an organic acid by hydrolysis and thermal decomposition and controlling a generated CO2 to a level not to exert a bad influence on cooling performances and having excellent compatibility with an insulating material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle and a refrigerant compressor, and more particularly to a chlorofluorocarbon-based refrigerant having a critical temperature of 40.degree.
The present invention relates to a refrigerating machine provided with a refrigerating machine oil composition conforming to a, and a refrigerating cycle constituent material such as an electric insulating material and a desiccant which are hardly deteriorated by the refrigerating machine oil composition.

[0002]

2. Description of the Related Art In recent years, chlorinated chlorofluorocarbons (chlorofluorocarbons) have been used worldwide due to problems of environmental pollution, particularly ozone depletion and global warming.
Fluorocarbons and CFCs are abbreviated for use, and alternative refrigerants have been promoted.

As an alternative refrigerant, hydrogen fluoride (HF) which has low reactivity with ozone and a short decomposition period in the atmosphere is used.
C) has attracted attention, and HFC134a is a representative of them, and is used as a refrigerant for refrigeration equipment of refrigeration equipment such as refrigerators and air conditioners (air conditioners).

Conventionally, mineral oil or alkylbenzene having good compatibility has been used as a refrigerating machine oil of a compressor of a refrigerating apparatus using CFC12 which is a kind of CFC as a refrigerant. In this combination, since it is completely compatible in all usage ranges of the refrigeration system, the so-called HFC134a in which the refrigeration oil stays in the heat exchanger and the two-layer separation phenomenon of the refrigeration oil and the refrigerant in the compressor and the refrigeration oil There was no need to worry about compatibility issues at all. But,
In the case of HFC134a, a chlorine-free fluorinated hydrocarbon-based refrigerant having unique properties, there was no practical refrigerating machine oil that easily dissolves the refrigerant. It was the biggest problem in practical use. For this reason, refrigerating machine oils having excellent compatibility with HFC134a have been actively developed, and various refrigerating machine oils have been proposed.

[0005] As typical examples thereof, compounds having an ether bond as exemplified below are known.

For example, in Japanese Patent Application Laid-Open No. 1-259093, propylene glycol monoether is used as "refrigeration oil for chlorofluorocarbon compressors", and in Japanese Patent Application Laid-Open No. 1-259094, diether is obtained by etherifying the terminal of propylene glycol. Compounds of the type described in
JP 25095 discloses a monoether type compound of propylene glycol and ethylene glycol copolymer.

[0007] These alkylene glycols are different from conventional mineral oils and alkylbenzene oils in that an ether bond is introduced into the molecule, thereby enhancing the affinity for chlorofluorocarbon 134a and greatly improving the compatibility. This improves the two-layer separation phenomenon and oil return to the compressor.

However, those containing a large number of ether bonds (C—O—C) in the molecule as described above have (1) a large saturated moisture absorption (easy to absorb water) and (2) a low volume resistivity. (3) There is a problem that the oxidation stability is poor and the total acid value is liable to increase, and this is unsuitable for a refrigerant compressor using a hermetic motor as an electric motor.

[0009] On the other hand, in order to improve such problems in the alkylene glycol, a refrigerating machine oil based on a compound having an ester bond (-COO-) in a molecule has been proposed.

For example, Japanese Patent Application Laid-Open No. 4-183788 discloses a refrigerating apparatus using a fatty acid ester oil represented by the following general formulas [Chemical Formula 3] to [Chemical Formula 7] as a refrigerating machine oil. The general formulas [Formula 3] to [Formula 6] are examples of hindered ester oils, and the general formula [Formula 7] is an example of complex ester oils.

[0011]

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[0012]

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[0013]

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[0014]

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[0015]

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Here, the characteristics of a conventional refrigeration system using ester oil as refrigeration oil will be described with reference to the drawings.

FIG. 5 is a refrigeration cycle diagram of a conventional refrigeration system. In FIG. 5, 1 is a compressor, 2 is a condenser, 3 is an expansion mechanism (for example, an expansion valve or a capillary tube), 4
Denotes an evaporator, 5 denotes a dryer (dryer), and 7 denotes refrigerating machine oil. The compressor 1 compresses a low-temperature, low-pressure refrigerant gas, and
The high-pressure refrigerant gas is discharged and sent to the condenser 2. The refrigerant gas sent to the condenser 2 becomes a high-pressure refrigerant while radiating the heat into the air, and is sent to the expansion mechanism 3 after the moisture in the liquid refrigerant is removed by the dryer 5. Then, by passing through the expansion mechanism 3, the steam becomes low-temperature, low-pressure wet steam and is sent to the evaporator 4. The refrigerant entering the evaporator 4 absorbs heat from the surroundings and evaporates, and the low-temperature, low-pressure refrigerant gas exiting the evaporator 4 is sucked into the compressor 1, and the same cycle is repeated thereafter.

Here, the inside of the evaporator 4 usually has a low temperature of -30 ° C. or lower, but the above-mentioned hindered ester oil containing two or more ester bonds in the molecule or complex ester oil is used as the refrigerating machine oil 7. By using the base oil as described above, the compatibility is increased to a critical dissolution temperature of -30 ° C. or lower, and the problem of the two-layer separation phenomenon is solved.

The fatty acid ester oil has a smaller moisture absorption rate than the polyalkylene glycol and has a volume resistivity of about 10 times, thereby improving the electrical insulation.

When the viscosity of the refrigerating machine oil is 40.degree.
By defining the range of 1 to 9 cSt at 70 cSt and 100 ° C., high efficiency and high reliability of the compressor 1 are achieved.

As described above, the hindered ester or complex ester refrigerating machine oil is HFC134a
Compatibility with high pressure type compressors and low pressure type compressors, and improve the problems of alkylene glycol.

On the other hand, Japanese Patent Application Laid-Open No. 4-63893 proposes a polycarbonate refrigerating machine oil containing carbonate as a main component represented by the general formula [Chemical Formula 8].

[0023]

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The polycarbonate oil shown here has a critical solubility temperature of <-30 ° C. or less with HFC134a, is compatible, and has a volume resistivity of 10 ^14.
It has the same electrical insulation property as the above-mentioned ester oil at about Ω · cm.

Further, it has been reported that unlike an ester oil, an organic acid is not generated during hydrolysis, and the ester oil is excellent in hydrolyzability.

As described above, the development of a refrigerating machine oil compatible with the HFC refrigerant has been promoted while the alternative refrigerant from the CFC to the HFC is progressing.

[0027]

However, as mentioned above, since the ester refrigerating machine oil contains an ester bond in the molecule as in the above-mentioned conventional art, the refrigerating machine oil is hydrolyzed or decomposed by water contained in the refrigerating cycle. Produces organic acids. The organic acid corrodes metals such as the mechanical part of the compressor in the refrigerating apparatus and generates a metal salt of an organic acid. Then, when precipitation begins on the capillary, which is an expansion mechanism, there is a possibility that the circulation of the refrigerant is obstructed and the cooling performance is reduced.

Further, in the refrigerating machine oil of polycarbonate,
Although organic acids generated by hydrolysis and thermal decomposition are small like esters, they generate a large amount of non-condensable gas, CO ₂ . The generated CO ₂ is mainly present in the condenser on the high pressure side of the refrigeration cycle, and may hinder the circulation of the refrigerant, reduce the cooling performance, and increase the input of the compressor.

Therefore, an object of the present invention is to provide a refrigerating machine oil having excellent electrical insulation properties, good compatibility with HFC, sufficient securing of compressor reliability and high efficiency, and
An object of the present invention is to provide a refrigerating apparatus using a refrigerating machine oil at a level at which generation of organic acids due to hydrolysis and thermal decomposition is small and there is no problem of precipitation on a capillary, and generated CO ₂ does not affect cooling performance.

[0030]

Therefore, the refrigerating apparatus of the present invention comprises at least a compressor, a condenser, an expansion mechanism, a drier and an evaporator, and has a viscosity in a refrigerating cycle using hydrofluorocarbon as a refrigerant. Is from 2 to 70 cSt at 40 ° C. and from 1 to 9 cSt at 100 ° C., using a refrigerating machine oil based on a monocarbonate oil having a carbonate bond (—O—CO—O—) in a molecule. It is. Here, the refrigerating machine oil is represented by the following general formula [Formula 9].

[0031]

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Alternatively, it is a monocarbonate represented by the following general formula [Chemical Formula 10] or a mixture of at least one monocarbonate represented by the general formulas [Chemical Formula 9] and [Formula 10].

[0033]

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According to the present invention, HF having excellent electrical insulation properties
Good compatibility with C, sufficient reliability of the compressor can be ensured, and the viscosity of the refrigerating machine oil can be realized with high efficiency, and the generation of organic acids due to hydrolysis and thermal decomposition is small and there is no problem of precipitation on the capillary. Further, it is possible to provide a refrigerating apparatus using refrigerating machine oil at a level at which generated CO ₂ does not affect cooling performance. Further, it is possible to provide a refrigeration apparatus which is excellent in compatibility with an organic material such as a motor insulating material of a compressor and a rubber material and which can secure long-term reliability.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a refrigeration cycle comprising at least a compressor, a condenser, an expansion mechanism, a dryer and an evaporator, and using hydrofluorocarbon as a refrigerant. A refrigerating machine oil having a viscosity of 2 to 70 cSt at 40 ° C. and 1 to 9 cSt at 100 ° C. and a monocarbonate oil having a carbonate bond (—O—CO—O—) in a molecule was used. Since the refrigerating apparatus is characterized by not having an ester bond (—COO—) in a molecular structure, it is possible to reduce an organic acid generated by hydrolysis or thermal decomposition as compared with a fatty acid ester oil. reducing the CO ₂ emissions compared to polycarbonate oil to carbonate bond a (-O-CO-O-) holds at least 1 pc is possible It has the effect of kill.

According to a second aspect of the present invention, there is provided the refrigeration apparatus according to the first aspect, wherein the refrigerating machine oil is a monocarbonate represented by the general formula [1]. Because it is a monocarbonate composed of only 6 to 10 alkyl groups, the critical dissolution temperature is −30 ° C. or less, and the compatibility is excellent, and the viscosity of the refrigerating machine oil at 40 ° C. can realize 2 to 10 cSt. Further, it has the effect of being highly reliable and capable of achieving high efficiency with respect to a low-pressure compressor.

According to a third aspect of the present invention, the refrigerating machine oil comprises a monocarbonate represented by the general formula [Chemical Formula 2] or a monocarbonate represented by the general formulas [Chemical Formula 1] and [General Chemical Formula 2] And a monocarbonate comprising a hydrocarbon group having an ether bond having 6 to 12 carbon atoms, or a mixture of the monocarbonate and the monocarbonate. Because it is a mixture of at least one or more monocarbonates composed of only alkyl groups having 6 to 10 carbon atoms, the critical melting temperature is −30 ° C. or less, the compatibility is excellent, and the viscosity of the refrigerating machine oil at 40 ° C. is 10%. ~ 70c
Since St can be realized, there is an effect that the reliability can be further improved and the efficiency can be increased with respect to the high-pressure compressor.

The difference between the characteristics of the conventional refrigerating machine oil and the refrigerating machine oil of the present invention will be described below with reference to Table 1. In Table 1, Comparative Example 1 is a hindered ester oil which is a conventional refrigerator oil, Comparative Example 2 is a polycarbonate oil which is a conventional refrigerator oil, Comparative Example 3 is a monocarbonate oil other than the present invention, Examples 1 to Examples 4 is a monocarbonate oil which is the refrigerator oil of the present invention. Further, the shield tube test in Table 1 was realized by the following method in accordance with JIS K2211 Appendix 2.

[0039] 6 mL of refrigerating machine oil has an outer diameter of 13 mm and an inner diameter of 9.
Enclose in a 0 mm glass tube. As a catalyst, iron (99%) having a wire system of 1.0 mm × length of 750 mm, copper (9
(9.99%) and two wires of aluminum (99.99%) were placed in a glass tube. Thereafter, the vacuum shield tube was sealed until the pressure in the glass tube reached 3.3 [MPa]. And at a temperature of 250 ° C.
Heated for 20 h.

[0040]

[Table 1]

Comparative Example 1 A compound synthesized from 2-ethylhexanoic acid and neopentyl glycol (NPG)
This is a mixture of a hindered ester blended with a carboxylic acid ester represented by Chemical Formula 12 synthesized from a carboxylic acid ester represented by 1), 2-ethylhexanoic acid, and pentaerythritol (PE).

[0042]

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[0043]

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Comparative Example 2 This is a mixture of a polycarbonate synthesized from tripropylene glycol and dimethyl carbonate.

[0045]

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(Comparative Example 3) A monocarbonate represented by the formula [Formula 14] synthesized from dimethyl carbonate and a branched alcohol having 10 carbon atoms.

[0047]

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Example 1 A compound synthesized from dimethyl carbonate and a branched alcohol having 10 carbon atoms [formula 1]
5] is a monocarbonate.

[0049]

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Example 2 Dimethyl carbonate was synthesized at a molar ratio of 3:97 between a branched alcohol having an ether bond having 12 carbon atoms and a branched alcohol having an ether bond having 9 carbon atoms. It is a mixture of monocarbonates represented by the following formulas [Formula 16], [Formula 17] and [Formula 18].

[0051]

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[0052]

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[0053]

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(Example 3) The molar ratio of dimethyl carbonate to a branched alcohol having an ether bond having 12 carbon atoms and a branched alcohol having 9 carbon atoms was 50:50.
Is a mixture of monocarbonates represented by the formulas [Formula 13], [Formula 14] and [Formula 19]. Here, the monocarbonate is synthesized using a branched alcohol having 9 carbon atoms.
And monocarbonate having the same structure as that of the above-mentioned monocarbonate oil.

[0055]

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From Table 1, it can be seen that the prior art hindered ester of Comparative Example 1 has a critical solution temperature of -50 with HFC134a.
Compatibility with ℃ is good, viscosity at 40 ℃ is 10c
St can be used in a low-pressure compressor and can achieve high efficiency. Also, at 250 ° C., 120
h From the result of the heated shield tube test, almost no generation of CO ₂ was recognized. However, the total acid value is 0.1.
It was as large as 66 [KOH mg / g]. This is because the hindered ester has an (-COO-) structure in the molecule, and thus has generated an organic acid by hydrolysis or thermal decomposition. The prior art polycarbonate of Comparative Example 2 had a critical solution temperature of -65 ° C or less and a viscosity of 90c.
The compatibility between St and HFC134a is ensured, and at the same time, an appropriate viscosity for the high-pressure compressor is realized. However,
As a result of the shield tube test, the total acid value was smaller than that of the hindered ester, but the amount of generated CO ₂ was considerably large at about 2000 mL. this is,
This is because the polycarbonate of Comparative Example 2 contains 2 to 7 carbonate structures (—O—CO—O—) in the molecule, and thus generates a large amount of CO ₂ by hydrolysis or thermal decomposition.

In contrast to these conventional refrigerating machine oils, the monocarbonate of Example 1, which is the refrigerating machine oil of the refrigerating apparatus according to the second aspect of the present invention, has a good volume resistivity and 9 carbon atoms. Since it is composed of only hydrocarbon groups and has one carbonate structure (—O—CO—O—), its critical dissolution temperature is -35 ° C. and its compatibility is good, and its viscosity is also 10 cSt.
And achieves an appropriate viscosity for a low-pressure compressor. In addition, the total acid value in the shield tube test was also 0.1.
01 [KOH mg / g], which was better than the hindered ester of Comparative Example 1. Further, the amount of generated CO ₂ was about 200 mL, which was reduced to about 1/10 as compared with the polycarbonate of Comparative Example 2.

The monocarbonate of Example 2 which is the refrigerating machine oil of the refrigerating apparatus according to claim 3 of the present invention has 9 carbon atoms.
And a hydrocarbon group having 12 ether bonds. This is to achieve a higher viscosity than the monocarbonate shown in Example 1. The viscosity can be increased by increasing the number of carbon atoms. However, as shown in Comparative Example 3, the monocarbonate obtained by adding two carbon atoms to the terminal of the monocarbonate of Example 1 has a higher viscosity, but has a critical solubility. When the temperature is 0 ° C. or higher, compatibility with HFC134a cannot be ensured. Thus, the monocarbonate of Example 2 employs a hydrocarbon group having an ether bond to have high viscosity and improve compatibility with HFC134a. As a result, as shown in Table 1, the volume resistivity was good, the critical dissolution temperature was -65 ° C. or less, the compatibility was good, and the viscosity was 13 cSt, which was higher than that of Example 1. The monocarbonate of Example 3 is composed of a hydrocarbon group having 9 carbon atoms and a hydrocarbon group having 12 ether bonds. In this structure, the volume resistivity is good, the critical dissolution temperature is -65 ° C or less, and the viscosity is 44 cSt.
And suitable viscosity for high pressure compressors. However, since the monocarbonates of Examples 2 and 3 contain an ether bond, the thermal stability is lower than that of the structure having only a hydrocarbon group, and the total acid value is 0.1 to 0.3 [KOHmg / g]. Slightly larger. However, the total acid value is clearly smaller than that of the conventional hindered ester, which is not a problematic level.

As described above, by using the monocarbonate according to claims 1 to 3 of the present invention as a refrigerating machine oil,
It has good compatibility with HFC134a and can realize an appropriate viscosity for increasing the efficiency of low-pressure and high-pressure compressors. Further, it was recognized that the amount of organic acid generated was smaller than that of the conventional hindered ester, and the amount of generated CO ₂ was smaller than that of polycarbonate.

The invention according to claim 4 of the present invention is characterized in that 0.01 to 5% by weight of a phosphate ester extreme pressure agent is added to refrigerating machine oil. This is a refrigeration apparatus, and the phosphate extreme pressure agent is a phosphate represented by the following general formula [Chemical Formula 20]. The surface of an iron-based sliding portion that forms a shaft and a bearing of a compressor. By forming a phosphoric acid ester chemically adsorbed film on the surface, the lubricating properties of the sliding portion are further improved, and the effect of preventing seizure and the like is obtained.

[0061]

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Specific examples of such phosphate ester extreme pressure agents include those represented by the following formula [Chemical formula 21].

[0063]

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In the present invention, the phosphate extreme pressure agent is preferably used in a proportion of 0.01 to 5% by weight, preferably 0.1 to 2% by weight, based on the base oil.

The invention according to claim 5 of the present invention is characterized by adding 0.01 to 5% by weight of a phenolic antioxidant represented by the following general formula [Chemical Formula 22] to refrigerating machine oil.
To Refrigeration apparatus according to any one of 4 to 4,
The phenolic antioxidant supplements the chain reaction products generated by the reaction of the base oil with the oxygen in the air mixed into the refrigeration cycle due to insufficient evacuation, etc. And the action of preventing generation of CO ₂ .

[0066]

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Specific examples of such a phenolic antioxidant compound include those represented by the formula [Formula 23].

[0068]

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In the present invention, the phenolic antioxidant compound is preferably used in a proportion of 0.01 to 5% by weight, preferably 0.05 to 5% by weight, based on the base oil.

In the invention according to claim 6 of the present invention, the compressor has a motor having an enamel-coated wire and an insulating film, wherein the enamel-coated wire is a polyester wire (PE);
Upper polyamide imide / lower polyester imide wire (A
I / EI) and polyamide-imide wire (AI), and the insulating film is made of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (P
EN), wherein the refrigerating apparatus according to any one of claims 1 to 5 is an insulating film of any one of the above (1) to (5), which is excellent in compatibility with an electric insulating material of a motor part of a compressor and is used for a long time. This also has the effect of preventing a decrease in the dielectric breakdown voltage of the enamel-coated wire and a decrease in the electrical insulation properties such as the tensile strength of the insulating film.

The material compatibility of the enameled wire and the insulating film of the motor of the compressor was confirmed by conducting the following tests. Refrigeration is performed using a simple system in which an internal system of 4.7 mm and a length of 700 mm is connected to the discharge side pipe and the suction side pipe of the low pressure type compressor, and both are connected by a capillary having an inner diameter of 0.8 mm and a length of 900 mm. The amount of HFC134a charged was adjusted so that 300 mL of machine oil was charged and the discharge pressure was 2.5 MPa and the suction pressure was 0.2 MPa, and the enamel coating wire temperature was 100 ° C under the conditions of 106 ° C and 162 ° C.
I ran for 0h. As the test oil, the refrigerating machine oil of Comparative Example 1 of the hindered ester shown in Table 1 and the refrigerating machine oil of Example 1 of the monocarbonate were used. In addition, the enamel-covered wire was obtained by multi-layer coating of an upper polyamide / lower polyester imide wire (AI to EI), and polyethylene terephthalate (PET) was used as an insulating film.

Table 2 shows the evaluation results of material compatibility after the test.
Shown in

[0073]

[Table 2]

From Table 2, it can be seen that, for the enamel-coated wire, the breakdown voltage was smaller than that of the new product, but there was no temperature dependence and the monocarbonate of the present invention was at the same level as the conventional hindered ester. Met. In addition, the one-way wear was at the same level and was good.

For the insulating film, the tensile strength,
It has been found that the monocarbonate of the present invention is less deteriorated than the conventional hindered ester in both weight average molecular weight and excellent in compatibility.

In the above test, the enamel-coated wire was not evaluated for the polyester wire (PE) and the polyamide-imide wire (AI), but is presumed to have the same characteristics. Further, as for the insulating film, it is estimated that polybutylene terephthalate (PET) and polyethylene naphthalate (PEN) have the same characteristics.

According to a seventh aspect of the present invention, there is provided the refrigeration apparatus according to any one of the first to sixth aspects, wherein the rubber material in the compressor comprises nitrile butadiene rubber (NBR). Since it has good compatibility with machine oil and does not swell even during long-term use, it has the effect of maintaining its function as a rubber seal material used in suction mufflers and the like.

The material compatibility of NBR was confirmed by performing the following tests. Immerse the NBR parts in the refrigerating machine oil, and one of the heating conditions is (150 ° C x 144
h → 30 ℃ × 48h) 5 cycles, one is 150 ℃
An immersion test was performed under two conditions of × 720 h. The refrigerant is H
FC134a was sealed in an amount that gave a pressure condition of 20 to 30 atm at the test temperature. As the test oil, the refrigerator oil of Comparative Example 1 of hindered ester and the refrigerator oil of Example 1 of monocarbonate were used. The test results are shown in [Table 3].

[0079]

[Table 3]

From Table 3, it was found that the monocarbonate of the present invention exhibited a smaller NBR weight change rate under each heating condition and was more excellent in compatibility than the conventional hindered ester.

The invention according to claim 8 of the present invention is characterized in that the water concentration in the refrigeration cycle is adjusted to 900 ppm or less based on the mixed weight of the refrigerant and the refrigerating machine oil. In this case, the amount of CO ₂ generated by hydrolysis with the refrigerating machine oil can be suppressed to a level that does not affect the performance. It has the effect that the cooling performance can be prevented from lowering even without a dryer.

A refrigerator using a low-pressure compressor with a normal internal volume of 300 L class is filled with 150 g of HFC134a and 300 g of refrigerating machine oil. The amount of water present in the refrigeration cycle is about 0.2 g, and is about 500 ppm based on the mixed weight of the refrigerant and the refrigerating machine oil.

The hydrolysis reaction of monocarbonate is represented, for example, by the following formula [Chemical Formula 24] for the refrigerating machine oil of Example 1.

[0084]

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From the formula (24), since 1 mol of CO ₂ is produced per 1 mol of H ₂ O, a typical refrigerator having a water content of about 0.2 g in the refrigerating cycle generates about 280 mL of CO ₂ at maximum. On the other hand, the effects of non-condensable gas on the cooling performance have been confirmed through the following tests.

Using the refrigerator described above, an ambient temperature of 30
The refrigerator was operated under the conditions of ℃ and JIS installation conditions, and 500 to 1500 mL of CO ₂ or air was sequentially sealed as a non-condensable gas, and the system temperature and the operation rate when the system was stabilized were evaluated.

FIG. 1 shows the operation rate, and FIG. 2 shows the temperature at the entrance of the dryer.
2 shows the measurement results. From FIG. _TwoDrives compared to air
The change in rate is small. Also, from FIG.
Is small, but the CO concentration is 2700ppm_Twoamount
At 1500 mL, the temperature has dropped by 4 ° C, and the refrigerant circulation has been impeded.
The effects were confirmed. Equivalent to a water concentration of 900 ppm
CO_TwoWith a volume of 500 mL, the temperature drop at the drying inlet is 2 ° C.
Yes, the effect on refrigerant circulation is small,
CO equivalent to a concentration of 500 ppm_Two280mL is no problem
It was confirmed.

As described above, if the water concentration is 900 ppm or less with respect to the mixed weight of the refrigerant and the refrigerating machine oil, the amount of generated CO ₂ does not affect the circulation of the refrigerant. It has been found that the decline can be prevented.

According to a ninth aspect of the present invention, there is provided the refrigeration apparatus according to any one of the first to eighth aspects, wherein the amount of air present in the refrigeration cycle is adjusted to 100 mL or less. Since the amount of air present in the refrigeration cycle is 100 mL or less, it has an effect of preventing a decrease in cooling performance.

Regarding the effect of air on the cooling performance,
From the results shown in FIGS. 1 and 2, it can be seen that air has a greater effect on cooling performance than CO ₂ . However, when the air amount is 100 mL or less, there is no change in the operation rate, and the temperature drop at the dryer inlet is also 2 ° C. or less, and the influence on the refrigerant circulation is reduced.

The tenth aspect of the present invention is characterized in that a synthetic zeolite having a carbon dioxide adsorption capacity of 2% by weight or more at 25 ° C. and 250 hPa is used as a desiccant in the dryer. Item 1 is a refrigeration apparatus according to any one of 1 to 9, wherein the desiccant adsorbs CO ₂ generated in the refrigeration cycle, it is possible to further reduce the amount of CO ₂ in the refrigeration cycle, This has the effect of preventing a decrease in cooling performance and an increase in the input of the compressor.

Generally, about 7 g of desiccant XH-9 having a CO ₂ adsorption capacity of 0.2% by weight at 25 ° C. and 250 hPa is used as a desiccant for a refrigerator dryer. In this case, CO ₂ generated by thermal deterioration or hydrolysis of the refrigerating machine oil exists mainly on the high pressure side of a refrigerating cycle in which a dryer is provided. And the pressure is 250
upon reaching hPa CO ₂ is not adsorbed only about 8mL the dryer. The pressure on the high pressure side of the refrigeration cycle is 250 hPa
, The refrigerator on which the low-pressure compressor is mounted has an internal volume of about 200 mL on the high pressure side, so about 70 mL of CO ₂ remains in the refrigeration cycle. In a refrigerator equipped with a high-pressure compressor, the internal volume on the high-pressure side is 1000 m
Since it is about L, about 350 mL of CO ₂ remains in the refrigeration cycle.

Similarly, when the desiccant 4AXH-6 having a CO ₂ adsorption capacity of 4.5% by weight is applied, the pressure becomes 25%.
When 0 hPa is reached, about 180 mL of CO ₂ is adsorbed on the dryer. Similarly, about 70 mL of CO ₂ remains in the refrigeration cycle when the low-pressure compressor is mounted, and about 350 mL when the high-pressure compressor is mounted.

Accordingly, by using a desiccant having a large CO ₂ adsorption capacity, the amount of CO ₂ in the refrigeration cycle can be reduced.

By increasing the filling amount of the desiccant, C
It is possible to use a desiccant having a smaller O ₂ adsorption capacity, but from a practical viewpoint, the CO ₂ adsorption capacity is 2% by weight.
It is desirable that this is the case. As described above, the remaining amount in the refrigeration cycle increases when the volume on the high pressure side is large.
It is preferable to use a desiccant having a large O ₂ adsorption amount.

[0096]

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a refrigeration cycle diagram of the refrigerator of the present embodiment. The refrigerator in the present embodiment has an internal volume of 420 L and is equipped with a low-pressure compressor. In addition, HFC of refrigerant
In this case, 140 g of 134a and 310 g of refrigerating machine oil are sealed.

In FIG. 3, portions denoted by the same reference numerals as those of the conventional example are portions having the same functions. In FIG. 3, 1
Is a compressor, 2 is a condenser, 3 is a capillary tube as an expansion mechanism, 4 is an evaporator, 5 is a dryer as a dryer, 6
Is refrigeration oil. The desiccant of the dryer 5 is 25 ° C., 25 ° C.
XH-9 made of synthetic zeolite mainly composed of potassium and sodium aluminate and silicic acid having a CO ₂ adsorption capacity of 0.2% by weight at 0 hPa was used. The refrigerating machine oil 6 uses the monocarbonate shown in Example 1 of Table 1 and has a 2,6-phenol phenol additive as an antioxidant.
It is obtained by adding 0.25 wt% of ditertiary butyl methyl phenol (DBPC). The water concentration in the refrigeration cycle is adjusted to 500 ppm or less based on the mixed weight of the refrigerant and the refrigerating machine oil. The amount of air present in the refrigeration cycle is adjusted to 50 mL or less.

FIG. 4 is a sectional view of the compressor of this embodiment. In FIG. 4, a compression element 9 for compressing a refrigerant and an electric element 10 for operating the compression element 9 are provided in a closed container 8, and a refrigerator oil 6 is stored at the bottom of the closed container 8.

The compression element 9 and the electric element 10 are connected by a drive shaft 11. The electric element 10 is constituted by a stator 12 and a rotor 13 instructed by a drive shaft 11 so as to keep a certain distance from an inner peripheral surface of the stator 12. The stator 10 has an insulating film as insulation between the enamel-coated wires and the correlation between the enamel-coated wires. The enamel-coated wire used was a multilayer-coated upper polyamide-imide / lower polyester imide wire (AI / EI). The insulation film is polyethylene terephthalate (PE
A film consisting of T) was used. Further, nitrile butadiene rubber (NBR) was used as a rubber material of a suction muffler (not shown).

A durability test was conducted in which the refrigerator having the above-described configuration was operated for 16200 hours under an overload installation condition of an ambient temperature of 43 ° C. In this test, 0.1% by weight of the antioxidant DBPC was added to the hindered ester shown in Table 1 (Comparative Example 1) with the same refrigerator specifications for comparison.
Was used as a refrigerating machine oil to which was added. Table 4 shows the results of measuring the cooling performance under the installation conditions described in JIS 9607 Annex 2 after the durability test.

[0101]

[Table 4]

From Table 4, it can be seen that in the conventional hindered ester (Comparative Example 1), the temperature at the dryer inlet was slightly decreased and the operation rate was slightly increased. In the case of carbonate, the cooling performance was good without any decrease in the temperature at the inlet of the dryer and no increase in the operation rate.

Next, the disassembly evaluation results after the durability test are shown in [Table 5].

[0104]

[Table 5]

From Table 5, it was confirmed that in the conventional hindered ester (Comparative Example 1), a small amount of precipitate mainly composed of iron carboxylate was present on the inner surface of the capillary. In addition, a slight increase in the total acid value and an increase in the amount of iron in the oil are observed, and it is estimated that the precipitate on the inner surface of the capillary is a product due to thermal degradation and hydrolysis of the oil.

On the other hand, in the monocarbonate of the present example (Example 1), the condition of the inner surface of the capillary was good, and no increase in the total acid value and the amount of iron in oil was observed. CO ₂
Although the amount of generated was larger in the monocarbonate of (Example 1) than in the hindered ester of (Comparative Example 1), it was not at a level affecting the cooling performance.

As a result of disassembly of the compressor, the monocarbonate of (Example 1) showed a small change in the dielectric breakdown voltage and the one-way wear of the enamel-coated wire compared to the hindered ester of (Comparative Example 1) and was excellent. The monocarbonate having the changes in the tensile strength and the weight average molecular weight of the insulating film (Example 1) showed little change compared to the hindered ester of (Comparative Example 1), and no deterioration was observed. Also, in the hindered ester of Comparative Example 1, the deterioration of the NBR parts of the suction muffler,
Some copper plating around the discharge valve was observed (Example 1)
Was good. The wear amount of each sliding component was also good, and exhibited abrasion resistance equal to or higher than that of the hindered ester of Comparative Example 1.

In this embodiment, XH-9 is used as a drying agent.
Was used, but the same characteristics were observed when XH-600 and XH-7 were used. 4ANRG with large CO ₂ adsorption capacity,
When 4AXH-6 is used, the amount of generated CO ₂ is further reduced.

In the present embodiment, the enamel-coated wire is
Although a multi-layer coating of the upper layer polyamide imide / lower layer polyester imide wire (AI / EI) was used, the same characteristics can be expected with a single coating of the polyester wire (PE) and the polyamide imide wire (AI). In this embodiment, the insulating film is made of polyethylene terephthalate (P
ET), but polybutylene terephthalate (PBT), polyethylene naphthalate (P
EN) can be expected to have the same effect.

[0110]

As described above, according to the present invention, the refrigerating cycle comprising at least a compressor, a condenser, an expansion mechanism, a dryer and an evaporator and using hydrofluorocarbon as a refrigerant has a viscosity of 40 ° C. 2 ~ 70c
St, 1 to 9 cSt at 100 ° C., using a refrigerating machine oil based on monocarbonate oil having a carbonate bond (—O—CO—O—) in the molecule, and the compressor is insulated from the enamel-coated wire. Having a motor with a film,
The enamel-coated wire is a polyester wire (PE), an upper polyamide imide / lower polyester imide wire (AI /
EI) and a polyamide imide wire (AI), and the insulating film is made of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PE).
N), any one of the insulating films
Good compatibility with FC, sufficient compressor reliability can be ensured, high-efficiency refrigerating machine oil viscosity can be realized, and organic acid generation due to hydrolysis and thermal decomposition is small and there is no problem of precipitation on the capillary. Further, it is possible to provide a refrigerating apparatus using refrigerating machine oil at a level at which generated CO ₂ does not affect cooling performance. Also, motor insulation materials for compressors,
It is possible to provide a refrigeration apparatus that is excellent in compatibility with organic materials such as rubber materials and can secure long-term reliability.

[Brief description of the drawings]

FIG. 1 is a characteristic diagram of an operation rate with respect to a non-condensable gas amount.

FIG. 2 is a characteristic diagram of a temperature at a dryer inlet portion with respect to a non-condensable gas amount.

FIG. 3 is a refrigeration cycle diagram of the refrigerator according to the embodiment of the present invention.

FIG. 4 is a sectional view of a compressor according to an embodiment of the present invention.

FIG. 5 is a refrigeration cycle diagram of a conventional refrigeration apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2 Condenser 3 Expansion mechanism 4 Evaporator 5 Dryer 6 Refrigerator oil 8 Airtight container 9 Compression element 10 Electric element 11 Drive shaft 12 Stator 13 Rotor

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // C10N 20:02 C10N 20:02 30:00 30:00 Z 40:30 40:30

Claims (10)

[Claims] 1. A refrigerating cycle comprising at least a compressor, a condenser, an expansion mechanism, a drier and an evaporator and using hydrofluorocarbon as a refrigerant, when the viscosity is 40 ° C., 2 to 70 cSt, and 100 ° C. 1-9
cSt, and a carbonate bond (-O-CO
A refrigerating machine characterized by using a refrigerating machine oil based on a monocarbonate oil having -O-). 2. The refrigerating apparatus according to claim 1, wherein the refrigerating machine oil is a monocarbonate represented by the following general formula [1]. Embedded image 3. The refrigerating machine oil is obtained by mixing at least one kind of a monocarbonate represented by the following general formula [Chemical formula 2] or a monocarbonate represented by the general formula [Chemical formula 1] and [Chemical formula 2]. The refrigeration device according to claim 1, wherein Embedded image 4. The refrigerating apparatus according to claim 1, wherein a phosphate ester extreme pressure agent is added to the refrigerating machine oil in an amount of 0.01 to 5% by weight. 5. The refrigerating apparatus according to claim 1, wherein a phenolic antioxidant is added to the refrigerating machine oil in an amount of 0.01 to 5% by weight. 6. The compressor has a motor having an enamel-coated wire and an insulating film, wherein the enamel-coated wire is a polyester wire (PE), an upper polyamideimide / lower polyesterimide wire (AI / EI) and a polyamide wire. Imide wire (AI) is any kind of enamel coated wire, and the insulating film is polyethylene terephthalate (PE)
The refrigeration apparatus according to any one of claims 1 to 5, wherein the refrigeration apparatus is any one of insulating films of T), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN). 7. The refrigeration apparatus according to claim 1, wherein the rubber material in the compressor comprises nitrile butadiene rubber (NBR). 8. The refrigeration apparatus according to claim 1, wherein a water concentration in the refrigeration cycle is adjusted to 900 ppm or less based on a mixed weight of the refrigerant and the refrigerating machine oil. 9. The amount of air present in the refrigeration cycle is 100 m.
The refrigeration apparatus according to any one of claims 1 to 8, wherein the refrigeration apparatus is adjusted to be equal to or less than L. 10. A desiccant in a dryer at 25 ° C., 2
2. A synthetic zeolite having a carbon dioxide gas adsorption capacity of 2% by weight or more at 50 hPa is used.
10. The refrigeration apparatus according to any one of claims 9 to 9.