JP2977971B2 - Lubrication method for compression refrigeration system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for lubricating a compression refrigeration system, and more particularly, to 1,1,1,2-tetrafluoroethane (R-134a) and 1,1-dichloro-2,2,3,4,5.
By using a specific hydrocarbon compound as a refrigerating machine oil together with an alternative chlorofluorocarbon-based refrigerant having 2,2-trifluoroethane (R-123) as a main component, the compression type refrigeration system is improved in abrasion resistance and cooling performance. And a method of efficiently lubricating without impairing stability.

[0002]

2. Description of the Related Art
In a compression refrigeration system including a compressor, a condenser, an expansion valve or a capillary tube, and an evaporator, fluorocarbons such as dichlorodifluoromethane (R-12) and chlorodifluoromethane (R-22) are used as refrigerants. Have been used. In addition, many refrigerating machine oils having no problem have been produced and used in combination therewith. However, these fluorocarbon compounds, which have been conventionally used as refrigerants, are suspected of destroying the ozone layer when released into the atmosphere. It has become That is,
1,1,1,2-tetrafluoroethane (R-134
a), 1,1,2,2-tetrafluoroethane (R-134b), 1,1-dichloro-2,2,2
2-trifluoroethane (R-123), 1-chloro-
1,1-difluoroethane (R-142b), 1,1-
Alternative chlorofluorocarbon-based refrigerants such as dichloro-1-fluoroethane (R-141b) have been developed and put on the market.
Among these alternative CFC-based refrigerants, R-134
a tends to be used instead of the conventional R-12 and R-22. In general, these alternative CFC-based refrigerants have different properties from conventional CFC-based refrigerants, and have a disadvantage that they are poorly compatible with mineral oil mainly used in conventional CFC-based refrigerants. Therefore, synthetic oils such as polyalkylene glycol compounds (PAG) and ester compounds have been developed and used as refrigerating machine oils suitable for these alternative Freon-based refrigerants (US Pat. No. 4,755,311).
No. 6, specification, JP-A-3-33193, etc.). However, these synthetic oils also have some problems with respect to the alternative CFC-based refrigerant. That is, although it has good compatibility with RAG-134a with PAG and ester, it has a drawback that stability is not sufficient. In addition, hydrocarbon compounds such as mineral oil having good stability with respect to R-134a are inferior in compatibility this time, and it is difficult to find a refrigerating machine oil that satisfies both requirements at the same time. Further, R-134a has a high vapor pressure, and therefore can be used alone in a compression refrigerator. However, R-1
No. 23 has a problem that it cannot be used other than a turbo refrigerator because the vapor pressure is low by itself, and further, there remains a problem in wear resistance, cooling property and the like.

[0003] Accordingly, the present inventor has proposed an R-type refrigerant which is recommended as an alternative chlorofluorocarbon-based refrigerant in a compression refrigeration system.
Intensive research was conducted on the lubrication method when 134a was used as a refrigerant. As a result, they found a method of efficiently lubricating a compression refrigeration system by using a combination of another alternative CFC-based refrigerant and a specific refrigeration oil. The present invention has been completed based on such findings.

[0004]

That is, the present invention relates to a compression refrigeration system comprising a compressor, a condenser, an expansion valve or a capillary tube, and an evaporator, wherein 1,1,1,2-tetrafluoroethylene is used as a refrigerant. Fluoroethane and 1,1-
A mixed refrigerant containing dichloro-2,2,2-trifluoroethane as a main component is used, and 4 g
Kinematic viscosity at 0 ° C is 5 to 500 cSt and interfacial tension is 20 dy
An object of the present invention is to provide a lubrication method for a compression refrigeration system, wherein a hydrocarbon compound having a ne / cm or more is used.

[0005] Generally, a compression refrigeration system comprises a compressor, a condenser, an expansion valve (or a capillary tube), and an evaporator. In general, the refrigerating machine oil used in the refrigerating system has good compatibility with the refrigerant used in the refrigerating system. However, when using the alternative Freon refrigerant in the above-mentioned compression type refrigeration system, lubricating with refrigeration oil generally used for refrigerators results in insufficient abrasion resistance or poor compatibility and poor stability. Due to lack of properties, long-term stable use was not possible. In particular, in a refrigeration system such as an electric refrigerator or a small air conditioner, this tendency is remarkable because a capillary tube is used as an expansion valve. The present invention has successfully and successfully solved such a problem.

First, in the present invention, the refrigerant is 1,1,
Mainly, 1,2-tetrafluoroethane (R-134a), and other 1,2-dichloro-2,2,2-trifluoroethane (R-12)
3) is selected and used together. As a result, even if the refrigerant is an alternative CFC-based refrigerant, not only synthetic oil but also mineral oil as the refrigerating machine oil can be lubricated in the compression type refrigerating system without any hindrance to the refrigerating efficiency.
In the present invention, R-134a and R-123 are used in combination. The mixing ratio of R-134a and R-123 may be appropriately selected depending on the situation, and usually R-134a and R-123 are used.
40-95% by weight of 4a, 60-5% by weight of R-123
Preferably, R-134a is set in a range of 50 to 85% by weight, and R-123 is set in a range of 50 to 15% by weight.
When the mixing ratio of R-134a is less than 40% by weight,
If the vapor pressure is lowered, the refrigeration efficiency may be deteriorated. If R-134a exceeds 95% by weight, the refrigerant and the refrigerating machine oil are easily separated into two layers, which is not preferable because the refrigeration efficiency is lowered. In addition, in the mixed refrigerant composed of R-134a and R-123, one or more of the refrigerants shown in the following first group and second group can be blended within 30% by weight. First group 1,3-dichloro-1,1,2,2,3-pentafluoropropane (R-225cb) 1,1-dichloro-2,2,3,3,3-pentafluoropropane (R-225ca) ) 1,1-Dichlorotrifluoroethane (R-141b) 1-Chloro-1,1-difluoroethane (R-142
b) Chlorotetrafluoroethane (R-124) Second group difluoroethane (R-152a) chlorodifluoromethane (R-22) pentafluoroethane (R-125) trifluoroethane (R-143a) difluoromethane (R-32) ) Trifluoromethane (R-23) Here, the first group of refrigerants has an effect of improving the solubility of the refrigerator oil, and the second group of refrigerants has an effect of increasing the vapor pressure.

On the other hand, the refrigerating machine oil has a kinematic viscosity at 40 ° C. of 5 to 500 cSt, preferably 10 to 300 cSt, and has a kinematic viscosity and an interfacial tension (JIS-K-2241) of 20 dyne / d. cm or more, especially 2
A hydrocarbon compound of 5 dyne / cm or more can be mentioned. Here, if the kinematic viscosity at 40 ° C. is less than 5 cSt, the lubricity deteriorates, and if it exceeds 500 cSt, the refrigerant and the refrigerating machine oil are separated into two layers, and the oil return is unfavorably deteriorated. There are various refrigerating machine oils that can be used in the present invention. Specific examples include paraffinic, naphthenic, aromatic and intermediate mineral oils. Examples of the synthetic oil include alkylbenzene, alkylnaphthalene, and olefin (co) polymer. Of course, various additives can be added to these refrigerating machine oils as needed.
The additives include extreme pressure agents such as phosphate esters and phosphite esters, antioxidants, chlorine scavengers, metal deactivators, defoamers, detergents / dispersants, viscosity index improvers, Rust agents, corrosion inhibitors, pour point depressants and the like can be mentioned.

[0008] In the present invention, the refrigerant mixture of CFC alternative and R-123, which is mainly composed of R-134a and R-123, can be used at various mixing ratios. 50-95% by weight, 50% refrigeration oil
It is used in a mixing ratio of ５5% by weight. By using the alternative CFC mixed refrigerant and the refrigerating machine oil at such a mixing ratio, the compatibility between the two and the lubricating property can be improved. Here, if the ratio of the refrigerating machine oil is too large, the vapor pressure of the refrigerant may decrease, which may cause a decrease in the refrigerating efficiency.

[0009]

Next, the present invention will be described in more detail based on examples and comparative examples. First, the properties of each refrigerating machine oil used in the examples and comparative examples, the mixing ratio of the alternative mixed CFC refrigerant, and other information are shown in Tables 1 and 2. The interfacial tension and hygroscopicity were measured as follows. 1) Interfacial tension Measured according to JIS-K-2241. 2) Hygroscopicity Take 10 g of refrigerating machine oil in a 50 cc beaker,
After being allowed to stand in a thermo-hygrostat at 85 ° C. and a humidity of 85% for 2 days, the amount of moisture absorbed (% by weight) was measured.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

Examples 1 to 7 and Comparative Examples 1 to 5 In each of the examples and comparative examples, the ratio between the refrigerating machine oil and the refrigerant was 1 unit.
0/90 (weight ratio), and a compression refrigerator (capacity 16) composed of "compressor-condenser-capillary tube-evaporator"
0W). The test results were as shown in Table 3.

[0015]

[Table 5]

[0016]

[Table 6]

Each performance test was performed as follows. 1) Measurement of two-layer separation temperature Mixing ratio of refrigerant oil and refrigerant (% by weight) = 10/90 2) Measurement of vapor pressure under oil-refrigerant mixing Ratio of refrigerant oil and refrigerant (% by weight) = 10/90 Temperature 40 ° C 3) Measurement of cooling rate of actual machine Freezer temperature of refrigerator (capacity 160W) is -20 ° C
Was evaluated based on the relative cooling rate to reach. 4) Shield tube test: 175 ° C, 10 days, catalyst: Fe, Cu, Al Refrigerant = 1 g, refrigerating machine oil = 4 cc, water = 1 wt% (based on oil) Test method The acid value was measured. 5) Falex abrasion test Refrigerant 10wt% mixed, rotation speed 290rpm, load 300L
Weared at bs for 60 minutes. The test piece used was a standard test piece.

[0018]

As described above, the alternative chlorofluorocarbon refrigerant is R
Even with 134a, use of R123 in combination with a hydrocarbon compound having a kinematic viscosity at 40 ° C. of 5 to 500 cSt and an interfacial tension of 20 dyne / cm or more makes it possible to use economically advantageous mineral oils and synthetic oils. Even in this case, the operation can be performed without any problem in wear resistance, cooling performance and stability. Therefore, the lubrication method of the present invention is particularly effective in reducing the size of a refrigeration apparatus, and its industrial utility value is high.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10M 107/02 C10M 107/02 // C10N 20:00 20:02 30:06 40:30 (58) Investigated field (Int. Cl. ⁶ , DB name) C10M 171/02 C09K 5/04 C10M 101/00-101/04 C10M 105/02-105/06 C10M 107/02-107/08 C10N 20:00 C10N 20:02 C10N 40: 30 CA (STN)

Claims (1)

(57) [Claims] In a compression refrigeration system comprising a compressor, a condenser, an expansion valve or a capillary tube, and an evaporator, 40 to 95% by weight of 1,1,1,2-tetrafluoroethane and 1,1 are used as refrigerants. 1-dichloro-2,2
A mixed refrigerant containing 60 to 5% by weight of 2-trifluoroethane as a main component is used.
Has a kinematic viscosity of 5-500 cSt and an interfacial tension of 20 dy
A method for lubricating a compression refrigeration system, wherein a hydrocarbon compound having a ne / cm or more is used.