JPH08100170A - Working fluid mixture - Google Patents

Abstract

PURPOSE: To prepare a working fluid mixture containing plural specific fluoroalkanes as essential components, free from the problem of ozonosphere disruption, having excellent refrigerant performance, usable without using a large-sized apparatus and useful for air conditioner, refrigerator, heat pump, etc. CONSTITUTION: This working fluid mixture contains (A) difluoromethane, (B) trifluoromethane, (C) tetrafluoromethane and (D) pentafluoromethane as essential components. The ratios of the components are preferably 3-40wt.% for the component A, 5-60wt.% for the component B, 5-60wt.% for the component C and 10-87-wt.% for the component D. In the case of using the mixture under a thermally severe condition, it is preferable to compound 100 pts.wt. of the mixture with 0.001-10 pts.wt., especially 0.01-5 pts.wt. of a stabilizer such as propylene oxide or diphenyl phosphite to further improve the thermal stability of the composition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to working fluid mixtures used in air conditioners, refrigerators, heat pump devices and the like.

[0002]

2. Description of the Related Art In recent years, chlorofluorocarbons (hereinafter, referred to as chlorofluorocarbons)
The environmental problem of ozone depletion due to the influence of (CFC) is drawing attention, and it has been decided to abolish it at the end of 1995.
In addition, hydrochlorofluorocarbons (hereinafter referred to as HCFCs), which have little influence on the destruction of the ozone layer, will eventually be completely abolished. Therefore, these CFCs
And the early development of alternatives to HCFCs. In particular, difluorochloromethane (hereinafter referred to as HCFC-22) used in low-temperature equipment is 48.8.
% By weight and pentafluoromonochloroethane (hereinafter CF
There is an urgent need to develop a medium that can replace the 51.2 wt% azeotropic mixture refrigerant (hereinafter referred to as C-115) (hereinafter referred to as R-502).

[0003]

SUMMARY OF THE INVENTION The main object of the present invention is to provide a working fluid mixture having an ozone depletion potential of zero, excellent performance as a refrigerant, and usable without major equipment improvement.

Although some candidate media have been disclosed so far, they cannot be said to have satisfactory performance. For example, JP-A-1-108291 discloses a mixed medium of trifluoroethane and pentafluoroethane. This mixed medium has excellent refrigerant performance,
The only drawback is the poor coefficient of performance.

Further, JP-A-6-170585 discloses a mixed refrigerant of three kinds of difluoromethane, tetrafluoromethane and pentafluoroethane. With this mixed refrigerant, it is possible to obtain a composition having an excellent refrigerating capacity and coefficient of performance, but the discharge pressure becomes extremely high, so the equipment strength must be increased. Further, the non-azeotropic property is large, and the temperature gradient in the heat exchanger is extremely large, which requires a large modification of the existing equipment.

On the other hand, JP-A-3-170588 discloses a mixed medium of trifluoroethane, tetrafluoroethane and pentafluoroethane. This mixed medium has performances that satisfy target values in terms of refrigeration capacity, discharge pressure, and discharge temperature, but has the drawback that the coefficient of performance is only inferior.

Further, JP-A-5-70769 discloses a mixed medium of difluoromethane and 1,1,1-trifluoroethane. This mixed medium has a serious safety problem because both components have a combustion range. Further, there is a drawback that the compressor discharge temperature increases as the proportion of difluoromethane increases. As described above, the two-component and three-component mixed media proposed so far cannot be said to have satisfactory properties over all the items required for the R-502 alternative refrigerant.

[0008]

DISCLOSURE OF THE INVENTION As a result of various researches in view of the above-mentioned technical situation, the present invention has revealed that difluoromethane (hereinafter referred to as HFC-32) which is a hydrofluorocarbon (hereinafter referred to as HFC). (1), trifluoroethane, tetrafluoroethane, and pentafluoroethane (hereinafter referred to as HFC-125) as essential components, a working fluid mixture having requirements meeting the purpose. Found out.

When the proportion of HFC-32 is high, there is a drawback that the discharge pressure and discharge temperature of the compressor rise, and there is a risk of flammability. If the proportion of HFC-32 is small, it has a drawback that a high coefficient of performance and a high refrigerating capacity cannot be obtained.
Therefore, the composition of HFC-32 in the mixture of HFC-32, trifluoroethane, tetrafluoroethane and HFC-125 (hereinafter referred to as mixture A) is 3 to 40% by weight, preferably 10 to 20% by weight. Is.

If the proportion of trifluoroethane in the mixture A exceeds 60% by weight, there is a danger of having flammability, and if it is too small, there is a drawback that the performance deteriorates. The composition of trifluoroethane is 5 to 60% by weight, especially 15 to 4
0% by weight is preferred.

When the proportion of tetrafluoroethane in the mixture A is high, the coefficient of performance is increased but the refrigerating capacity is deteriorated. As a result of examination including compressor discharge pressure and discharge temperature characteristics, 5 to 60% by weight, especially 15 to 40%
Weight percent is preferred.

The proportion of pentafluoroethane in the mixture A has an effect of suppressing the combustibility of difluoromethane and trifluoroethane, and the mixing proportion thereof is determined by the composition of the other three refrigerants, but is particularly 10-87. % By weight, preferably 25-60% by weight.

The tetrafluoroethane used in the present invention includes 1,1,2,2-tetrafluoroethane (hereinafter referred to as HFC-134) and 1,1,1,2-tetrafluoroethane (hereinafter referred to as HFC). (-134a)
Are known, but they may be used alone or as a mixture thereof because they have similar physical properties to each other.

Further, as trifluoroethane, 1,
1,1-trifluoroethane (hereinafter HFC-143a
And 1,1,2-trifluoroethane (hereinafter referred to as
HFC-143)) are known. For the purpose of the present invention, HFC-143a having a standard boiling point of about -47 ° C. is superior, and HFC-1
Although it is preferable to use 43a alone, HFC-143a including isomer HFC-143 may be used.

The working fluid mixture of the present invention is effective when applied to a refrigeration cycle for the purpose of air conditioning, refrigeration and refrigeration in the low to medium temperature and high temperature fields, but for Rankine cycle and other various heat recovery techniques. It can also be used as a working fluid.

The working fluid mixture of the present invention has excellent thermal stability and does not require a stabilizer under normal use conditions, but when it is necessary to improve thermal stability due to severe use conditions, Propylene oxide, 1,2-butylene oxide, epoxides such as glycidol, dimethyl phosphite, diisopropyl phosphite, phosphite such as diphenyl phosphite, thiophosphite such as trilauryl trithiophosphite, triphenoxyphosphine sulfide, Phosphine sulfides such as trimethylphosphine sulfide, boron compounds such as boric acid, triethylborate, triphenylborate, phenylboronic acid and diphenylboronic acid, phenols such as 2,6-di-t-butyl-p-cresol, Nitro Tan, nitroalkanes such as nitroethane, methyl acrylate, acrylic acid esters such as ethyl acrylate, and other dioxane, tert
-Stabilizers such as butanol, pentaerythritol, paraisopropenyltoluene, 0.001-10 parts by weight, preferably 0.0, parts by weight per 100 parts by weight of the working fluid mixture.
1 to 5 parts by weight can be blended.

Further, the working fluid mixture of the present invention contains HFCs such as trifluoromethane and 1,1-difluoroethane other than the mixture A within a range not impairing the object of the present invention.
, Ethers such as dimethyl ether, pentafluoroether and perfluorodimethyl ether, amines such as perfluoroethylamine and perfluorodimethylamine, hydrocarbons such as propane and butane, perfluoro compounds such as perfluoroethane and perfluoropropane Compounds such as can be further mixed.

[0018]

【Example】

"Examples 1 to 7, Comparative Examples 1 to 5" In a 1-hp refrigerator filled with a working fluid mixture having the composition shown in Table 1, the evaporation temperature of the refrigerant in the evaporator was -30 ° C, and the refrigerant was condensed in the condenser. The operation was carried out at a temperature of 40 ° C., a compressor inlet superheat degree of 0 ° C., and an expansion valve inlet supercooling degree of 0 ° C. Polyalkylene glycol oil was used as the refrigerator oil. The coefficient of performance (COP), refrigeration capacity, compressor discharge pressure,
Table 2 shows the compressor discharge temperature and the condenser inlet / outlet temperature difference.

As shown in Examples 1 to 6, the working fluid mixture of the present invention has a coefficient of performance and a refrigerating capacity equivalent to those of R-502, and a maximum increase in compressor discharge pressure and discharge temperature is 300 kPa. Only 8 ℃. Furthermore, the maximum temperature difference in the heat exchanger (condenser inlet / outlet temperature difference) is 4 ° C., which is a working fluid mixture with non-azeotropic properties suppressed.
It will be appreciated that it will perform as well as or better than the R-502 without significant modification of conventional equipment.

On the other hand, HFC-143a / shown in Comparative Example 1
Binary mixed medium consisting of HFC-125, HFC-143a / HFC-134a / HFC-12 shown in Comparative Example 3
The ternary mixed medium consisting of 5 has the drawback of a low coefficient of performance. In addition, HFC-32 / HFC-shown in Comparative Example 2
The two-component mixed medium consisting of 125 has excellent coefficient of performance and refrigerating capacity, but it has a drawback that it requires significant improvement of the equipment because the discharge pressure and discharge temperature of the compressor rise significantly, which makes it practical. Not. In addition, HFC-shown in Comparative Example 4
The ternary mixed medium composed of 32 / HFC-134a / HFC-125 has an excellent coefficient of performance, but has a drawback that the compressor discharge temperature and the temperature inside the heat exchanger are large.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

INDUSTRIAL APPLICABILITY The present invention has excellent performance as an R-502 alternative medium used especially in the low temperature field,
The same performance as R-502 can be obtained without major equipment modification.

Further, since hydrofluorocarbon is an essential component, there is no effect on ozone layer depletion.

Claims (2)

[Claims] 1. Difluoromethane, trifluoroethane,
A working fluid mixture comprising tetrafluoroethane and pentafluoroethane as essential components. 2. Difluoromethane, trifluoroethane,
When the mixing ratio of tetrafluoroethane and pentafluoroethane is difluoromethane / trifluoroethane / tetrafluoroethane / pentafluoroethane = 3 to 40% by weight / 5 to 60% by weight / 5 to 60% by weight / 10 to 87% by weight 2. The working fluid mixture of claim 1.