JPH0625340B2 - Working medium and its use - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a working medium composed of a refrigerant and a lubricating oil used in a refrigerator equipped with a refrigeration compressor or an air conditioner, and particularly to a working medium having excellent heat resistance.

[Conventional technology]

In recent years, in the field of refrigerators and air conditioners, miniaturization and high performance of refrigeration compressors have been promoted, and in particular, demand for quick freezing has increased in refrigerators, and high-speed rotation is trying to cope with this. Since the discharge temperature of the refrigerant increases due to this high speed rotation, a working medium having excellent heat resistance is required to realize this.

Heretofore, among the working media used for this, a combination of dichlorodifluoromethane as a refrigerant for a refrigerator or an air conditioner and naphthene-based mineral oil as a lubricating oil as the other medium has been frequently used. In most cases, as a means for improving heat resistance, a lubricating oil having excellent thermal stability in the presence of a refrigerant has been selected. However, since this refrigerant has chlorine in its molecule, it has a drawback that it desorbs chlorine when exposed to high temperatures, and this chlorine accelerates deterioration of oil.

On the other hand, a method of changing the refrigerant to improve heat resistance is also considered, and various fluorinated hydrocarbons are known as refrigerants having a boiling point similar to that of dichlorodifluoromethane and having no chlorine in the molecule.

[Problems to be Solved by the Invention]

However, the disadvantage of this refrigerant is that it is poorly compatible with the other medium, the lubricating oil, and is not compatible with the naphthenic mineral oil that has been widely used as a lubricating oil until now. Pp. 816, (1985)].

By the way, when operating a refrigeration compressor, a mixture of a working medium, refrigerant and lubricating oil, is pumped up from the bottom of the compressor and supplied to sliding parts such as bearings to reduce friction and prevent seizure. It has become. However, if the refrigerant and the lubricating oil are separated into two phases in the compressor, only the refrigerant having a large specific gravity is supplied, the desired oil film is not formed due to the low viscosity, and the sliding portion may be seized. Most of the refrigerant is compressed by the compressor and carried to the refrigeration cycle consisting of a condenser, evaporator and expansion valve, and participates in refrigeration work, but part of the lubricating oil also circulates in the refrigeration cycle along with the refrigerant. ． At this time, if the refrigerant and the lubricating oil are separated in the evaporator, which becomes a low temperature, the high-viscosity lubricating oil remains at that location, which not only lowers the thermal efficiency of the evaporator, but also may cause a shortage of lubricating oil in the compressor. is there.

The present invention has been made in view of such a current situation, and an object thereof is to provide a working medium for a refrigerating compressor comprising a fluorocarbon as a refrigerant and a lubricating oil having excellent compatibility. is there.

[Means for Solving the Problems]

Briefly describing the present invention, the present invention relates to a working medium, which is a fluorine-containing hydrocarbon refrigerant containing no chlorine and bromine and the following general formula I: And a trifluoroethylene low-polymerization product having a molecular weight of 500 to 800 represented by the following formula as an essential component.

INDUSTRIAL APPLICABILITY The working medium of the present invention is useful as a working medium for a refrigerating compressor, for example, a refrigerator and an air conditioner.

The fluorinated hydrocarbon-based refrigerant of the present invention is a refrigerant having excellent heat resistance as compared with conventional dichlorodifluoromethane, and it is thought that this refrigerant cannot be applied, and various liquids that can be used as a lubricating oil of a refrigeration compressor. As a result of examining the compatibility with fluorinated hydrocarbon refrigerants, as a liquid that does not undergo two-phase separation up to a low temperature at any concentration,
The present invention has been completed by finding a trifluoroethylene chloride low polymer represented by the general formula I.

It is presumed that this trifluoroethylene low-polymerization product has compatibility with one another because it is similar in molecular structure to the fluorocarbon refrigerant which is one medium. Due to this compatibility, sufficient lubrication of the refrigerating compressor can be expected, which makes it possible to improve the efficiency of refrigerators and air conditioners.

Further, this trifluoroethylene low polymer is excellent in heat resistance and chemical resistance, is a liquid that can be used even in a corrosive atmosphere, and can be obtained as a commercial product (for example, Daifloyl manufactured by Daikin Industries, Ltd., Asahi Glass Co., Ltd. CFC).

It should be noted that a silicone oil-based defoaming agent may be added to the working medium as long as the object of the present invention is not impaired.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Examples 1-2, Comparative Examples 1-6 Molecular weight 500 (viscosity 3 cSt, 40 ° C.) and molecular weight 800
The critical dissolution temperature of the trifluoroethylene low-polymerization product (viscosity 80 cSt, 40 ° C.) and the fluorocarbon refrigerant was measured. For comparison, the critical dissolution temperature was measured with naphthene-based mineral oil (viscosity 30 cSt, 40 ° C.) and alkylbenzene (viscosity 34 cSt, 40 ° C.) used in conventional refrigerators and air conditioners, as well as various liquids.

The critical dissolution temperature here was measured as follows. A thermometer is inserted into a liquefied gas sampling tube made of pressure-resistant glass having a volume of 100 m, and various liquids such as a certain amount of oil (for example, 3.5 m), such as trifluoroethylene chloride low polymer, are weighed.

After attaching this container to the refrigerant introduction device and exhausting the system,
After cooling with a dry ice-methanol bath, about 60 m of fluorinated hydrocarbon was introduced into the container from a refrigerant cylinder and weighed to obtain the oil concentration. Then the container is again dried ice-
Insert in a methanol bath and gradually cool.

During this process, the temperature is raised occasionally, and the temperature at which turbidity occurs when shaken well is continued, and this temperature is taken as the two-phase separation temperature at that oil concentration. Next, the refrigerant in the container is reduced and re-weighed, that is, the oil concentration is changed to determine the two-phase separation temperature. This operation is repeated.

The oil concentration dependence of the two-phase separation temperature thus obtained is schematically shown in FIG. That is, Fig. 1 shows the oil concentration (wt%, horizontal axis) and the two-phase separation concentration (° C, vertical axis).
It is a graph which shows the relationship with. The peak temperature of the diagram shown is the lower limit temperature at which the refrigerant and the oil are compatible with each other at an arbitrary ratio (this is called the critical dissolution temperature), and the lower side of the curve is the region where two phases are separated.

The critical dissolution temperatures of the examples and comparative examples thus measured are shown in Tables 1 and 2.

As is clear from Table 1, the critical melting temperature of 1,1,1,2-tetrafluoroethane and the trifluoroethylene chloride low polymer is -20 ° C or lower. That is, at -20 ° C,
No two-phase separation at any oil concentration. On the other hand, among the comparative examples, dioctyl sebacate showing a low critical dissolution temperature is 30 ° C., and all other liquids are 40 ° C. or higher. Table 2 shows that 1,1,2,2-tetrafluoroethane, It is the critical dissolution temperature of 1,1-difluoroethane and hexafluoropropane with the lubricating oil. The combination with the trifluoroethylene low polymer is compared with the combination with dioctyl sebacate, which has a relatively low critical solution temperature with 1,1,1,2-tetrafluoroethane in the comparative example of Table 1. Even so, it has remarkably excellent compatibility.

The fluorinated hydrocarbon-based refrigerant according to the present invention does not contain chlorine in the molecule unlike conventional refrigerants, and thus may be inferior in flammability. So 200m / from a copper pipe with an inner diameter of 1mm
The refrigerant was made to flow out at a flow rate of a minute, and the presence or absence of combustion when the gas burner flame was applied to this was examined. The flammability of each refrigerant is shown in Table 3. Of the four types of refrigerants, 1,1-difluoroethane has a flammability, so caution is required when applying it.

[Effects of the Invention] As described above, according to the present invention, when the fluorocarbon-based refrigerant is used as a working medium of a refrigerator, an air conditioner or the like, by combining it with the lubricating oil of the present invention, The two-phase separation can be avoided even at low temperatures, and the efficiency and durability of refrigerators and air conditioners can be improved.

[Brief description of drawings]

FIG. 1 is a graph schematically showing the oil concentration dependence of the two-phase separation temperature of the refrigerant and the lubricating oil.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C10N 20:04 30:00 Z 8217-4H 40:00 Z 8217-4H 40:08 (72) Invention Tohru Iizuka, 800, Tomita, Ohira-cho, Shimotsuga-gun, Tochigi, Ltd., Tochigi Plant, Hitachi, Ltd. (56) References JP 62-283193 (JP, A) JP 61-179288 (JP, A)

Claims (4)

[Claims] 1. A fluorine-containing hydrocarbon-based refrigerant which does not contain chlorine and bromine, and the following general formula I: A working medium characterized in that a trifluorinated ethylene chloride low polymer having a molecular weight of 500 to 800 represented by 2. A fluorine-containing hydrocarbon refrigerant containing no chlorine or bromine is 1,1,1,2-tetrafluoroethane, 1,1,2,2-
The working medium according to claim 1, which is selected from tetrafluoroethane, 1,1-difluoroethane and hexafluorocyclopropane. 3. A refrigerator characterized by using the working medium according to claim 1 as the working medium. 4. An air conditioner using the working medium according to claim 1 as the working medium.