JPH0959611A - Refrigerant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerant composition being an azeotropic refrigerant mixture comprising 1,1,1,2-tetrafluoroethane and isobutane and having a boiling point substantially equal to that of a regulated refrigerant, CFC 12 or CFC 500. SOLUTION: This refrigerant composition is obtained by forming an azeotropic mixture comprising 88-71wt.% 1,1,1,2-tetrafluoroethane and 12-29wt.% isobutanc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant composition used in a refrigeration system and having no danger of destroying the ozone layer.

[0002]

2. Description of the Related Art R12 (dichlorofluoromethane) and R50 are conventionally used as refrigerants for refrigerators.
0 (R12 and R152a (1,1-difluoroethane)
Azeotropic mixture with) is often found. The chemical formula of R12 is CCl2F2
It is. Also, its boiling point is -29.65 ° C at atmospheric pressure, and R
The boiling point of 500 is −33.45 ° C., which is suitable for ordinary refrigeration equipment. Further, even if the suction temperature into the compressor is relatively high, the discharge temperature does not become high enough to cause oil sludge of the compressor. Furthermore, R12 has good compatibility with oils of conventional compressors such as mineral oil and alkylbenzene oil, and also plays a role of returning oil in the refrigerant circuit to the compressor.

However, each of the refrigerants, due to its high ozone depletion potential, destroys the ozone layer when it is released into the atmosphere and reaches the ozone layer above the earth. It is known that the destruction of the ozone layer is caused by the chlorine group (Cl) in the refrigerant.

Therefore, this chlorine-free refrigerant, such as R125 (pentafluoroethane) or R134a, is used.
(1,1,1,2-Tetrafluoroethane) is considered as an alternative refrigerant for these. The boiling point of R125 is −48 ° C. at atmospheric pressure, and the boiling point of R134a is −26 ° C.

Further, R22 (chlorodifluoromethane) contains a chlorine group (Cl), but since it has a hydrogen group (H), it is actively decomposed before reaching the ozone layer. The coefficient of destruction is smaller than that of R12. The boiling point of R22 is −40.75 ° C. at atmospheric pressure.

These are described in the prior US Pat. No. 48104.
No. 03 is also mentioned and some examples of blends using these refrigerants which do not destroy the ozone layer are shown.

[0007]

The above-mentioned U.S. Pat. No. 5,837,058 discloses some examples in which a refrigerating capacity equivalent to that of R12 (dichlorofluoromethane) is exhibited by blending a plurality of refrigerants that do not destroy the ozone layer. In addition, R125, etc., which do not contain a chlorine group (Cl), can also be used as a refrigerant containing a chlorine group (Cl) and a hydrogen group (H).
22 and blends by R142b et al. Are shown.

However, the following disadvantages occur in the refrigerant blend as shown in the related art. That is, the refrigerants containing no chlorine group (Cl), R125 and R134a, have extremely poor compatibility with oils such as mineral oils and alkylbenzene oils conventionally used in compressors of refrigeration cycles. It has a chlorine group (C
This is because it depends on the existence of l). Further, although R22 also has a chlorine group (Cl), its compatibility with oil is not good.

When the oil of the compressor does not dissolve in the refrigerant, two-phase separation (separation of oil and refrigerant) occurs in the evaporator of the refrigerant circuit, the oil is not returned to the compressor, and the bearing sliding portion of the compressor is not returned. There is a risk of burning.

An object of the present invention is to solve various problems of the prior art.

[0011]

According to the invention of claim 1,
The refrigerant composition is composed of an azeotropic mixture of 1,1,2-tetrafluoroethane and isobutane, and has a boiling point lower than the boiling point of each of them.

The invention of claim 2 provides a refrigerant composition comprising an azeotropic mixture of 1,1,1,2-tetrafluoroethane of 88% by weight to 71% by weight and isobutane of 12% by weight to 29% by weight. It has a boiling point of −33.7 ° C. and can exhibit sufficient refrigerating capacity as an alternative refrigerant for R12 and R500, and can be used as it is for a compressor using conventional mineral oil or alkylbenzene oil as refrigerating machine oil. It was done like this.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a refrigerant circuit diagram of a normal refrigeration cycle.
FIG. 2 is a characteristic diagram of the azeotropic refrigerant mixture of the present invention.

1 is a compressor driven by an electric motor, 2
Is a condenser, 3 is a capillary tube, 4 is an evaporator, and these are sequentially connected. The compressor 1 is filled with a conventional refrigerating machine oil such as mineral oil or alkylbenzene oil. In addition, the chemical formula in the refrigerant circuit is chlorine group (Cl)
Refrigerant not containing 1,1,1,2-tetrafluoroethane (hereinafter referred to as R134a) and isobutane (hereinafter referred to as R600)
a)) azeotrope. Its composition is 88 to 71 wt% R134a, R600a
Is 12 to 29% by weight.

The operation of the refrigerant in the refrigerant circuit in FIG. 1 will be described. The high-temperature high-pressure gaseous azeotrope discharged from the compressor 1 flows into the condenser 2 to radiate heat, is decompressed by the capillary tube 3 and flows into the evaporator 4, where it evaporates and exerts cooling capacity, Return to the compressor 1. Since R134a that forms an azeotrope is an HFC refrigerant, it does not mix with the conventional refrigerating machine oil such as mineral oil or alkylbenzene oil, but R600a is compatible with the conventional refrigerating machine oil and discharges from the compressor 1 Is melted and returned to the compressor 1. Thereby, the refrigerating machine oil in the refrigerant circuit is collected in the compressor 1 without stagnation.

Further, R134a, which is an HFC refrigerant, does not dissolve in conventional refrigerating machine oil, but has good compatibility with ester oil, and an azeotropic mixture with this refrigerant R600a is used for air conditioning of mineral oil, alkylbenzene oil, ester oil, etc. , Can be used as refrigerating machine oil for refrigeration compressors.

The azeotropic mixture of R134a and R600a can be used as an alternative refrigerant for R12 and R500 because it can obtain a cooling temperature of -33.7 ° C. obtained in the evaporator 4, and can be used as a normal freezing showcase or the like. Has been made available.

Also, since R600a has a high boiling point and is flammable, if the mixing ratio is too large, the required cooling temperature cannot be obtained in the evaporator 4 and there is a risk of explosion, but on the contrary, it is small. If it passes, the oil return function will not work. Experiments show that R60
0a is preferably 12 to 29% by weight of the whole,
It is preferably 22 and 2% by weight.

Further, R134a and R600a are generalized refrigerants and are easily available.

[0020]

EFFECT OF THE INVENTION According to the refrigerant composition of the present invention, there is no risk of depleting the ozone layer, and the compatibility with conventional compressor oils such as mineral oil and alkylbenzene oil is excellent.
Since oil in the refrigerant circuit is returned to the compressor by a, it is possible to prevent seizure of the compressor.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of the present invention.

FIG. 2 is a characteristic diagram of the azeotropic refrigerant mixture of the present invention.

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Capillary tube 4 Evaporator

Claims (2)

[Claims] 1. A refrigerant composition comprising an azeotropic mixture of 1,1,1,2-tetrafluoroethane and isobutane. 2. 88% by weight to 71% by weight of 1,1,1,2-tetrafluoroethane and 12% by weight of isobutane.
To 29% by weight of an azeotropic mixture.