JP2980448B2 - Lubrication method for compression refrigeration cycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubrication method for a compression refrigeration cycle, and more particularly, to a specific lubricant together with an alternative fluorocarbon refrigerant such as 1,1,1,2-tetrafluoroethane (R-134a). The present invention relates to a method for effectively lubricating a compression refrigeration cycle without impairing abrasion resistance, cooling performance and stability by using a combination thereof.

[0002]

2. Description of the Related Art
In a compression refrigeration cycle including a compressor, a condenser, an expansion valve, and an evaporator, a fluorocarbon fluorocarbon compound such as dichlorodifluoromethane (R-12) or chlorodifluoromethane (R-22) is used as a refrigerant. Used
In addition, many lubricants having no problem have been produced and used in combination therewith. However, it has been feared that this fluorocarbon compound, which has been conventionally used as a refrigerant, may destroy the ozone layer and cause environmental pollution when released into the atmosphere. Recently, from the aspect of environmental pollution countermeasures, the development of fluorinated hydrocarbons (or chlorofluorohydrocarbons) such as 1,1,1,2-tetrafluoroethane (R-134a), which can be used as an alternative, has been promoted. , Already R-13
In addition to 4a, 1,2,2-tetrafluoroethane (R-134) and the like, various so-called alternative fluorocarbons which are less likely to cause environmental pollution and can satisfy the above-mentioned required characteristics have come to market. It is coming. This new alternative CFC-based refrigerant has different properties from the conventional CFC-based refrigerant, and glycol compounds and ester compounds have been proposed as lubricants to be used in combination therewith (US Pat. No. 4,755,316). However, there are still problems in abrasion resistance, cooling performance and stability.

[0003] The present inventor has studied the use of an alternative Freon-based refrigerant in a compression refrigeration cycle and a lubricant suitable for the alternative Freon-based refrigerant. As a result, they have found that a compression-type refrigeration cycle can be efficiently lubricated by using a combination of a CFC substitute refrigerant and a specific lubricant. The present invention has been completed based on such findings.

[0004]

That is, the present invention relates to a compression refrigeration cycle having an oil separator and / or a hot gas line in a refrigeration cycle system comprising a compressor, a condenser, an expansion valve and an evaporator. 1,1,1,2 as refrigerant
-Tetrafluoroethane (R-134a); 1,1,
2,2-tetrafluoroethane (R-134); 1,1
-Dichloro-2,2,2-trifluoroethane (R-1
23); 1-chloro-1,1-difluoroethane (R-
142b); 1,1-difluoroethane (R-152
a); trifluoromethane (R-23); difluoromethane (R-32); pentafluoroethane (R-12).
5) and 1,1,1-trifluoroethane (R-143)
a) An alternative chlorofluorocarbon-based refrigerant having at least one selected from the group consisting of: a) having a kinematic viscosity at 100 ° C. of 2 to 50 cSt and an interfacial tension of 2 as a lubricant;
An object of the present invention is to provide a lubrication method for a compression refrigeration cycle, wherein a lubricant that is liquid at room temperature of 5 dyne / cm or more is used.

[0005] Usually, a compression refrigeration cycle is composed of a compressor, a condenser, an expansion valve, and an evaporator. Generally, a lubricant having good compatibility with a refrigerant used for a refrigerator is used. However, when an alternative refrigerant is used in the above refrigeration cycle, if the refrigerator is lubricated with a commonly used lubricant, or the wear resistance is insufficient,
Lack of stability prevented long-term stable use. Especially,
This tendency is remarkable when a capillary tube is used as an expansion valve as in a refrigeration cycle of an electric refrigerator or a small air conditioner.

The present invention has been completed based on an idea completely opposite to ordinary common sense in order to solve such a problem. That is, the lubricant used in the refrigeration cycle has been completed based on the idea that compatibility with the refrigerant used in the refrigeration cycle is not necessarily required. Accordingly, certain conditions are added to the refrigeration cycle. That is, the present invention provides a method for operating a compression refrigeration cycle having an oil separator and / or a hot gas line using 100 ° C.
Has a kinematic viscosity of 2 to 50 cSt, preferably 3 to 30 cSt.
And a liquid lubricant at room temperature with an interfacial tension of 25 dyne / cm or more, preferably 30 to 80 dyne / cm. There are various lubricants that can be used in the present invention as lubricants having such characteristics. Specifically, various types of lubricants, such as mineral oil (paraffin, naphthene, and intermediate) lubricants, (For example, alkylbenzene, alkylnaphthalene, poly-α-olefin and the like). Various additives can be blended with these lubricants. The additives include phosphate esters,
Including extreme pressure agents such as phosphites, antioxidants, chlorine scavengers, metal deactivators, defoamers, cleaning dispersants, viscosity index improvers, rust inhibitors, corrosion inhibitors, pour point depressants Agents and the like.

On the other hand, the refrigerants used in the present invention include R-134a, R-134 and R-1 as described above.
23, R-142b, R-152a, R-23, R-3
2, R-125 and R-143a.
These may be used alone or in combination of two or more, and R-134a and R-32 are particularly optimal. When two or more kinds are mixed, R-134a and R-32, R-32 and R-125, or R134a
a, a combination of R-32 and R-125 is preferred.
In addition, the following refrigerants may be mixed and used in a relatively small ratio. That is, the refrigerants that can be mixed and used are chlorotetrafluoroethane (R-124), dichlorotetrafluoroethane (R-141b), 1,1-dichloro-2,2,3,3,3-pentafluoropropane (R
-225ca), 1,3-dichloro-1,1,2,2
3-pentafluoropropane (R-225cb) and the like.

[0008]

Next, the present invention will be described in more detail with reference to examples. Examples 1 to 9 and Comparative Examples 1 to 4 Actual equipment tests were performed using various compression refrigeration cycles.
The results are as follows. The expansion valve used was a capillary tube type. Method of compression refrigeration cycle A: Compression refrigeration cycle of "compressor-condenser-expansion valve-evaporator" having an oil separator and a hot gas line (see Fig. 1) B: "Compressor having an oil separator -Compressor refrigeration cycle of "condenser-expansion valve-evaporator" (see Fig. 2) C: Compressor refrigeration cycle of "compressor-condenser-expansion valve-evaporator" having a hot gas line (see Fig. 3) D: Compression refrigeration cycle of "compressor-condenser-expansion valve-evaporator" (see FIG. 4). D is for comparison. In the actual machine test, R-134a was used as a CFC substitute refrigerant for the A, B, C, and D refrigerators having an output of 100 W, and a refrigeration test was performed for one year with the following lubricant. Operating conditions Suction temperature: -40 ° C Condensation temperature: 30 ° C Evaluation method 1. The temperature of the evaporator was measured. 2. The operation was stopped when an abnormality occurred, and each part was observed to investigate the cause. Table 1 shows the lubricants used in the freezing test.

[0009]

[Table 1]

Table 2 shows the results of the actual machine test.

[0011]

[Table 2]

Examples 10 to 18 and Comparative Examples 5 to 8 The same refrigeration test was carried out using R-32 as an alternative chlorofluorocarbon-based refrigerant. Table 3 shows the results of the actual test.

[0013]

[Table 3]

[0014]

As described above, even if the refrigerant is an alternative CFC-based refrigerant, the kinematic viscosity at 100 ° C. is 2 to 50 c as in the present invention.
If a liquid lubricant is used at room temperature, which is St and has an interfacial tension of 25 dyne / cm or more, operation can be performed without any problem in wear resistance, cooling performance, and stability. Therefore, the method of the present invention is particularly effective in downsizing a refrigeration apparatus, and its industrial value is high.

[Brief description of the drawings]

FIG. 1 is a flowchart of a method A of a compression refrigeration cycle applied in the present invention.

FIG. 2 is a flowchart of a B-type compression refrigeration cycle applied in the present invention.

FIG. 3 is a flowchart of a C type of a compression refrigeration cycle applied in the present invention.

FIG. 4 is a flowchart of a D system diagram of a compression refrigeration cycle applied to a comparative example.

[Explanation of symbols]

 1: Compressor 2: Condenser 3: Expansion valve 4: Evaporator 5: Oil separator 6: Hot gas line 7: Valve for hot gas line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI F25B 1/00 387 F25B 1/00 387B // C10N 20:00 20:02 30:06 40:30 (58) Int.Cl. ⁶ , DB name) C10M 101 / 02,105 / 04 C10M 105 / 06,107 / 02 C09K 5/04 F25B 1/00 387 C10N 40:30

Claims (5)

(57) [Claims] 1. A compression refrigeration cycle having an oil separator and / or a hot gas line in a refrigeration cycle system comprising a compressor, a condenser, an expansion valve, and an evaporator. Tetrafluoroethane; 1,1,
1,2-difluoroethane; 1,1-difluoroethane; trifluoromethane; difluoromethane; a CFC-based alternative containing at least one selected from the group consisting of pentafluoroethane and 1,1,1-trifluoroethane Use refrigerant and 100
Kinematic viscosity at 2 ° C. is 2 to 50 cSt and interfacial tension is 25 to 5
A lubrication method for a compression refrigeration cycle, characterized by using a liquid lubricant at a normal temperature of 3.8 dyne / cm . 2. The lubrication method for a compression refrigeration cycle according to claim 1, wherein the compression refrigeration cycle has an oil separator in a refrigeration cycle system including a compressor, a condenser, an expansion valve, and an evaporator. 3. The lubrication method for a compression refrigeration cycle according to claim 1, wherein the compression refrigeration cycle has a hot gas line in a refrigeration cycle system including a compressor, a condenser, an expansion valve, and an evaporator. 4. The compression type refrigeration cycle has an oil separator and a hot gas line in a refrigeration cycle system including a compressor, a condenser, an expansion valve, and an evaporator.
A lubrication method for the compression refrigeration cycle as described above. 5. The lubrication of a compression refrigeration cycle according to claim 1, wherein the lubricant is at least one selected from paraffinic mineral oil, naphthenic mineral oil, alkylbenzene, alkylnaphthalene and poly-α-olefin. Method.