JP2003004320A - Refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration unit using a refrigerating machine oil and a refrigerant containing a hydrofluorocarbon as a working fluid capable of stably working for a long time with suppressing production pf sludge. SOLUTION: An ester-based refrigerating machine oil comprising an ester oil compatible with the hydrofluorocarbon and composed of an unsaturated aliphatic acid as a constituent aliphatic acid is used as the refrigerating machine oil of the refrigeration unit employing the refrigerating machine oil and the refrigerant containing the hydrofluorocarbon as the working fluid in order to suppress the production of the sludge and ensure reliability for a long time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerating apparatus which uses a refrigerant containing hydrofluorocarbon and refrigerating machine oil as a working medium and is provided with an expansion mechanism such as a refrigerating compressor, a condenser, a capillary tube and an evaporator.

[0002]

2. Description of the Related Art Conventionally, in refrigerators, refrigerators, air conditioners, etc., CFCs containing fluorine and chlorine as refrigerants such as R11 (trichloromonofluoromethane) and R12 (dichlorodifluoromethane) which are chlorofluorocarbons (CFCs), Hydrochlorofluorocarbon (HCF
C22 such as R22 (monochlorodifluoromethane) has been used. However, most of these CFC compounds are not decomposed when released into the atmosphere, destroy the ozone layer in the stratosphere, and adversely affect biological systems, and their use is being regulated internationally. Therefore, studies on alternative CFC substances that do not contain chlorine have been widely made. As an alternative to these CFCs and HCFCs, hydrofluorocarbons (H
FC) has come into use. However, in a refrigeration cycle using these HFCs as a refrigerant, polyalkylene glycol (PA) is used from the viewpoint of compatibility with the refrigerant.
It is necessary to use a refrigerating machine oil having polarity such as G) and esters. Since the HFC of the refrigerant itself has a high polarity, the working medium consisting of the refrigerant and the refrigerating machine oil itself has a very high water absorption, and it is necessary to pay attention to deterioration of the refrigerating machine oil. Therefore, Japanese Patent Application Laid-Open No. 4-122792 proposes a refrigeration cycle equipped with an ion exchange resin or an epoxy compound in order to suppress deterioration of refrigerating machine oil. Further, as a refrigerating machine oil, a method of adding various acids and water scavengers to ensure the stability of the base oil has been proposed.
For example, JP-A-4-36387 in which an epoxy-containing fluorine-containing polysiloxane is added to 100 parts by weight of lubricating oil, JP-A-4-55498 in a PAG refrigerating machine oil containing di- or trivalent polyol glycidyl ether, ester oil. JP-A-5-17792 for a refrigerating machine oil composition in which a di- or polyglycidyl ether compound is added to a mixture of benzene and an alkylbenzene or mineral oil, and JP-A-1-1 for a lubricating oil composition in which an epoxy-containing polysiloxane is added.
No. 93393, the alicyclic epoxy compound 0.05-
JP-A-5-105896 in which 15 parts by weight are blended, JP-A-5-209171 in a composition for a working fluid of a refrigerator in which a compound having an epoxycyclohexyl (or pentyl) group is blended in a polyol ester, and glycidyl ether in ester oil JP-A-6-1970 of a composition for refrigerator working fluid to which a type epoxy compound is added, an epoxy compound which is an ethyl-glycidyl ether substituted at the 2-position with two alkyl groups having 1 to 4 carbon atoms is blended. JP-A-6-88087 for refrigerating machine oil, JP-A-6-240279 for refrigerating machine oil in which a base oil is mixed with an epoxy compound selected from the group consisting of limonene oxide, α-pinene oxide and L-carboxylic oxide, poly Aromatic mono- or dicarboxylic acid glycidyl or epoxy cycloalkyl groups on ether JP-6-240277 discloses a refrigerating machine oil chromatic compound was added, JP-A of the refrigerating machine oil obtained by blending an unsaturated alcohol ester-based base oil 6-17078
JP-A-6-240278, which is a refrigerating machine oil in which hydrogen or a C1-20 alkyl group and ethylene oxide having a C4-20 hydroxyalkyl group substituted in the α and β positions are blended with the base oil, an ester or an ester. JP-A-6-287585 for a lubricating oil for a refrigerator in which a glycidylamine compound is blended in a mixture with a mineral oil or a synthetic oil, JP-A-6-336594 for a refrigerator oil in which an epoxy compound is added to a polyether oil, and a polyol ester JP-A-6-293893, which is a refrigerating machine oil containing a compound having an epoxycyclohexyl group or an epoxycyclopentyl group, and a refrigerating machine oil containing a carbodiimide compound have been proposed, "Research on hydrolysis of ester and acid scavenger" (Japan Tribology). Conference Tribology Conference Proceedings No. 4 69-472, 1994).

[0003]

In a refrigeration cycle equipped with an ion exchange resin, an anion exchange resin can be used to trap organic acids and inorganic acids. However, on the other hand, the hydrolysis of the polyol ester oil is accelerated due to the basicity of the ion exchange resin, an acid component exceeding the acid scavenging capacity is generated, and as a result, sludge generation cannot be suppressed. there were. On the other hand, when an acid / moisture scavenger is added to the refrigerator oil, the added acid / moisture scavenger captures the organic acid generated by the hydrolysis of the ester oil that is the refrigerator oil. Generation of salt can be suppressed. However, the added acid / water scavenger often causes a polymerization reaction as a side reaction at the same time as it captures the acid, and as a result, there is a problem that it causes capillary clogging due to a polymer having a large molecular weight. Further, when the extreme pressure agent is added to the refrigerating machine oil, particularly when it is added excessively, the phosphorus-based extreme pressure agent tends to cause a corrosion reaction, and there is a drawback that remarkable corrosion is caused when the corrosion reaction occurs. Further, when the dryer is removed from the refrigerating apparatus for cost reduction, it is necessary to improve the stability of lubricating oil having high hygroscopicity. Furthermore, when unsaturated alcohol is added, water absorption is increased, so that more strict water management is required.

In consideration of the problems of the conventional refrigerating apparatus, the present invention operates a refrigerant containing hydrofluorocarbon and refrigerating machine oil capable of suppressing sludge formation and performing stable operation for a long period of time. It is an object of the present invention to provide a refrigerating device as a medium. Another object is to suppress the polymerization reaction between ester oils and avoid the occurrence of defects due to water.

[0005]

The refrigerating apparatus of the present invention made in view of the above points is a refrigerating apparatus in which a refrigerant containing hydrofluorocarbon and refrigerating machine oil are used as working media, as described in claim 1. The refrigerating machine oil is characterized in that it is an ester refrigerating machine oil that is compatible with the hydrofluorocarbon and contains unsaturated fatty acids. Also,
The refrigerating apparatus according to claim 2 is the refrigerating apparatus according to claim 1, wherein a refrigerant containing hydrofluorocarbon and refrigerating machine oil are used as working media, and the refrigerating machine oil is compatible with the hydrofluorocarbon. An ester-based refrigerating machine oil comprising an ester oil containing a saturated fatty acid and an unsaturated fatty acid as a constituent fatty acid, and / or an ester oil compatible with the hydrofluorocarbon and containing a saturated fatty acid as a constituent fatty acid, and at least an unsaturated fatty acid constituting a fatty acid. The ester-based refrigerating machine oil is obtained by mixing the ester oil with Further, a refrigerating apparatus according to claim 3 is the refrigerating apparatus according to claim 1 or 2, wherein the unsaturated fatty acid is a monovalent unsaturated fatty acid.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The refrigerating machine oil used in the refrigerating apparatus according to the present invention is an ester refrigerating machine oil compatible with hydrofluorocarbons and containing unsaturated fatty acids.
Specific ester refrigerating machine oils containing unsaturated fatty acids, which consist of ester oils that are compatible with hydrofluorocarbons and that have saturated fatty acids and unsaturated fatty acids as constituent fatty acids, and / or compatibility with hydrofluorocarbons. There is a mixture of an ester oil having a saturated fatty acid as a constituent fatty acid and an ester oil having at least an unsaturated fatty acid as a constituent fatty acid.

The ester oil which is compatible with the hydrofluorocarbon which constitutes the ester-based refrigerating machine oil according to the present invention can dissolve the hydrofluorocarbon used as a refrigerant and enhance the lubricity of the sliding portion in the compressor. if it whatever including known ones. Such ester oil is generally synthesized from a polyhydric alcohol and a saturated fatty acid by a dehydration reaction. As the polyhydric alcohol, neopentyl glycol, pentaerythritol, dipentaerythritol, etc. are used according to the viscosity of the refrigerating machine oil. As one saturated fatty acid, linear fatty acids such as hexanoic acid, heptanoic acid, nonanoic acid, and decanoic acid, and 2-methylhexanoic acid,
Branched chain fatty acids such as 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid are used. It should be noted that ester oils containing straight chain fatty acids have good sliding properties but are inferior in hydrolyzability, and ester oils containing branched chain fatty acids have characteristics in that they are slightly inferior to sliding properties but are difficult to hydrolyze. Should be.

One embodiment of the ester-based refrigerating machine oil according to the present invention is obtained by substituting unsaturated fatty acid for a part of saturated fatty acid which is a constituent fatty acid of ester oil having compatibility with hydrofluorocarbon as described above. is there. Such ester oil is synthesized by dehydration reaction from polyhydric alcohol, saturated fatty acid and unsaturated fatty acid. There is no limitation on the number of unsaturated bonds in the unsaturated fatty acid, but if it is 2 or more, the reactivity becomes too high, which is not preferable. Further, many compounds having triple bonds have high reactivity, which is not preferable.

Therefore, as the unsaturated fatty acid used in the present invention, 2-hexenoic acid, 3-hexenoic acid, 6-hexenoic acid as a monovalent unsaturated fatty acid having one unsaturated bond is used.
It can be said that straight-chain fatty acids such as heptenoic acid, 10-undecylenic acid and 2-octenoic acid, as well as 2,2-dimethyl-4-pentenoic acid, 2-ethyl-2-hexenoic acid and citronellic acid are desirable.

Another embodiment of the ester-based refrigerating machine oil according to the present invention is a mixture of the above-mentioned ester oil having compatibility with hydrofluorocarbon and ester oil having at least unsaturated fatty acid as a constituent fatty acid. . Both ester oils can be synthesized by the dehydration reaction as described above.

The ester oil containing unsaturated fatty acid as a constituent fatty acid has a function of trapping an acid remaining in the refrigerating apparatus and has an effect of suppressing the generation of sludge. In addition, the unsaturated bond has a function of coordinating with the iron on the sliding surface, and has an effect of preventing corrosion of iron.

[0012]

Embodiments of a refrigerating apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a refrigerating apparatus according to an embodiment of the present invention. It is a block block diagram of a refrigeration equipment provided with a refrigeration compressor, a condenser, an expansion mechanism, and an evaporator. As shown in FIG. 1, the refrigeration system includes a refrigeration compressor 1 for compressing a refrigerant containing hydrofluorocarbon, a condenser 2 for condensing the refrigerant, an expansion mechanism 3 for expanding the refrigerant, such as a capillary, and an evaporator for the refrigerant. And an evaporator 4 for connecting the pipes 5 for connecting these,
It is composed of a four-way valve 6 and an accumulator 7, and uses refrigerant and refrigerating machine oil as working media. Then, by switching the four-way valve 6, the flow path of the working medium is changed, and the functions of the condenser and the evaporator are exchanged. In the refrigeration system of this embodiment,
Except for using an ester-based refrigerating machine oil containing an unsaturated fatty acid that is compatible with hydrofluorocarbons,
The configuration of the refrigerating apparatus itself is almost the same as that of a conventionally known one, and detailed description of the configuration of the refrigerating apparatus and its operation will be omitted.

In the following description, in a refrigerating machine using a refrigerant containing hydrofluorocarbon and a refrigerating machine oil as a working medium, an ester oil which is compatible with hydrofluorocarbon and has a saturated fatty acid as a constituent fatty acid is used as the refrigerating machine oil, and In this embodiment, a mixture of an ester oil containing a saturated fatty acid as a constituent fatty acid is used. The mixing ratio of ester oil containing unsaturated fatty acid as a constituent fatty acid is not particularly specified. If there is a change in refrigerator oil viscosity due to mixing,
It is necessary to avoid mixing a large amount or to adjust the viscosity by mixing other ester oil components. The method for mixing the ester oil containing unsaturated fatty acid as a constituent fatty acid is not particularly limited. It is possible to use a method in which an ester oil containing unsaturated fatty acids as constituent fatty acids is separately synthesized and then added to the base oil. Refrigerating machine oil consisting of ester oil having compatibility with hydrofluorocarbon and saturated fatty acids and unsaturated fatty acids as constituent fatty acids is synthesized by mixing polyhydric alcohol as a raw material, saturated fatty acids and unsaturated fatty acids in appropriate proportions. To do. Further, known additives such as an antioxidant, an acid scavenger and an antiwear agent may be added to the refrigerating machine oil of the present invention. As the antioxidant, known phenol-based or naphthylamine-based compounds such as dibutylparacresol can be used. As the acid scavenger, a compound having one epoxy group in one molecule does not cause a polymerization reaction, so that it is desirable to use it. As the antiwear agent, a phosphorus-based one can be used, but since the ester oil has a high polarity, it is difficult for the phosphorus-based compound to appear at the interface between the iron and the refrigerating machine oil, and the addition amount must be increased. However, it should be noted that the phosphorus-based extreme pressure agent may have an adverse effect on aluminum if the amount added is excessively increased.

Hereinafter, the ester-based refrigerating machine oil which is compatible with the hydrofluorocarbon and contains unsaturated fatty acid according to the present invention will be described with reference to specific examples. (Example 1) Pentaerythritol was used as a polyhydric alcohol, and saturated fatty acids such as 2-ethylhexanoic acid and 3,5,5 were used.
5-trimethylhexanoic acid and 2-which are unsaturated fatty acids
An ester oil was synthesized by dehydration condensation using three types of octenoic acid. At this time, the mixing ratio of the polyhydric alcohol and the organic acid was 80, pentaerythritol, 10, 2-ethylhexanoic acid, 9,3,5,5-trimethylhexanoic acid, and 2-octenoic acid in a molar ratio.
Then, it was confirmed by a gas chromatograph-mass spectrometer that the ester oil having the unsaturated fatty acid was synthesized, that is, the ester refrigerating machine oil containing the unsaturated fatty acid was prepared.

Example 2 Pentaerythritol was used as a polyhydric alcohol, and saturated fatty acids 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid and unsaturated fatty acids 2-ethyl-2-hexenoic acid. An ester oil was synthesized by dehydration condensation using the above three types of fatty acids. At this time, the mixing ratio of the polyhydric alcohol and the organic acid is 80, pentaerythritol is 10, 2-ethylhexanoic acid is 10, 3,5,5-trimethylhexanoic acid is 9, and
2-Ethyl-2-hexenoic acid was set to 1. And, that ester oil having unsaturated fatty acids can be synthesized,
That is, it was confirmed by a gas chromatograph-mass spectrometer that an ester-based refrigerating machine oil containing an unsaturated fatty acid was prepared.

Example 3 Ester oil was synthesized by dehydration condensation using pentaerythritol as a polyhydric alcohol and saturated fatty acids 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid as acids. Next, ester oil was synthesized by dehydration condensation using neopentyl glycol as a polyhydric alcohol and 2-octenoic acid as an unsaturated fatty acid. Furthermore, 9 ester oils with saturated fatty acids
1 part of an ester oil containing an unsaturated fatty acid was mixed with 1 part to prepare an ester refrigerating machine oil containing an unsaturated fatty acid.

Example 4 Ester oil was synthesized by dehydration condensation using pentaerythritol as a polyhydric alcohol and saturated fatty acids 2-ethylhexanoic acid and 3,5,5-trimethylhexanoic acid as acids. Next, pentaerythritol as a polyhydric alcohol and linoleic acid as a divalent unsaturated fatty acid were used to synthesize an ester oil by dehydration condensation. Furthermore, 9 ester oils with saturated fatty acids
1 part of an ester oil containing an unsaturated fatty acid was mixed with 1 part to prepare an ester refrigerating machine oil containing an unsaturated fatty acid.

(Reliability Test) The reliability test was carried out as follows. A dryer was not used in all reliability tests. (Reliability test 1 to 4) The refrigerating machine oil prepared in the above Examples 1 to 4 is put in a compressor to prepare a 2.8kW type room air conditioner (refrigerating device), and cooling is performed while keeping the discharge temperature at about 115 ° C. Continuous operation was carried out. The room air conditioner created here contains 300 g of refrigerator oil, 700 g of refrigerant R410A, and 1 g of water.
Was filled. (Reliability Test Comparative Examples 1 and 2) A room air conditioner similar to those used in the reliability tests 1 to 4 was used as a comparative example except for the refrigerating machine oil.
In Comparative Example 1, pentaerythritol and 2 were used as refrigerating machine oils.
-Ethylhexanoic acid and 3,5,5-trimethylhexanoic acid were mixed at a molar ratio of 4: 2: 2, and ester oil consisting of only saturated fatty acids synthesized by dehydration condensation was used. In Comparative Example 2, 3% of tricresyl phosphate was added to the ester oil consisting of the saturated fatty acid of Comparative Example 1 and used as a refrigerator oil. (Results) After operating for 3000 hours, the room air conditioner was disassembled and the constituent parts were analyzed. In Comparative Example 2, discoloration of the oil was observed. On the other hand, in Examples 1 to 3, the oil had almost no discoloration. In Example 4, some discoloration was observed. When the capillary tube was cut, in Examples 1 to 3, no conspicuous deposit was found on the inner surface of the pipe. In Example 4, some deposits were seen. Comparative Example 1
In Nos. 2 to 3, a large amount of sludge-like substances adhered to the inner surface of the pipe. That is, in the reliability test of the refrigerating apparatus according to the present invention (Example), since the ester oil containing unsaturated fatty acid is used as the refrigerating machine oil, since the unsaturated bond is adsorbed on the iron surface, the generation of sludge is suppressed. It is thought to have been done.

[0019]

Since the present invention is constructed as described above, it has the following effects. According to the first or second aspect of the present invention, in a refrigerating apparatus using a refrigerant containing hydrofluorocarbon and refrigerating machine oil as a working medium, the refrigerating machine oil is compatible with hydrofluorocarbon and unsaturated fatty acids are constituent fatty acids. By using the ester oil, the unsaturated bond effectively acts on the iron surface, so that the generation of sludge can be suppressed. Therefore, the long-term reliability is further improved as compared with the conventional case. Further, according to the invention described in claim 3, by making the unsaturated fatty acid monovalent, it is possible to suppress the wasteful polymerization reaction of ester oils with each other, and the durability of the refrigerating device against moisture is improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a refrigerating apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 Refrigeration compressor 2 condenser 3 expansion mechanism 4 evaporator 5 piping 6 four-way valve 7 Accumulator

Claims (3)

[Claims] 1. A refrigerating machine using a refrigerant containing hydrofluorocarbon and a refrigerating machine oil as working medium, wherein the refrigerating machine oil is an ester type refrigerating machine oil compatible with the hydrofluorocarbon and containing an unsaturated fatty acid. Refrigerating device characterized by. 2. A refrigerating apparatus using a refrigerant containing hydrofluorocarbon and refrigerating machine oil as a working medium, wherein the refrigerating machine oil is compatible with the hydrofluorocarbon and is an ester oil containing a saturated fatty acid and an unsaturated fatty acid as constituent fatty acids. And / or an ester-based refrigeration obtained by mixing an ester oil having compatibility with the hydrofluorocarbon and having a saturated fatty acid as a constituent fatty acid and an ester oil having at least an unsaturated fatty acid as a constituent fatty acid. The refrigerating apparatus according to claim 1, which is a machine oil. 3. The refrigerating apparatus according to claim 1, wherein the unsaturated fatty acid is a monovalent unsaturated fatty acid.