JPH0532961A - Mixed cooling medium containing trifluoromethane - Google Patents

Abstract

PURPOSE:To provide the title cooling medium excellent in various characteristics required for the cooling media for refrigerating machines such as freezing capacity, accomplishment factor and delivery gas temperature, also having no adverse effects on the ozone layer even if released into the atmosphere, consisting of a mixture of specific fluoroalkanes. CONSTITUTION:The objective mixed cooling medium consisting of (A) trifluoromethane and (B) compound(s) selected from pentafluoroethane, tetrafluoroethane and octafluorocyclobutane. The weight ratio is normally pref. as follows: (A) component A=5-50wt.% and (B) component B=95-50wt.%. In the case higher stability is needed under severe working conditions, it is recommended that ca.0.01-5wt.% of a stabilizer such as propylene oxide be added to the present cooling medium.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to refrigerants.

[0002]

2. Description of the Related Art Conventionally, monochloropentafluoroethane (CFC11), which is one of regulated chlorofluoroalkanes, has been used as a refrigerant used in a low-temperature refrigerator.
R502 including 5) is mainly used. However, when regulated chlorofluoroalkanes containing chlorine such as CFC115 are released into the atmosphere, they are stable for a long period of time and, therefore, rise to the stratosphere without decomposition,
Therefore, it has been pointed out that the chlorine radicals generated by decomposition destroy the ozone layer and, as a result, have a serious adverse effect on the earth's ecosystem including humankind.

Therefore, there is an urgent need to develop a refrigerant that does not destroy the ozone layer and can replace R502 containing a regulated chlorofluoroalkane.

Chlorofluoroalkanes or fluoroalkanes which are considered as alternatives to R502 include dichloromonofluoromethane (HCFC21), trifluoromethane (HFC23) and difluoromethane (HFC).
32), monochlorotetrafluoroethane (HCFC1
24), pentafluoroethane (HFC125), monochlorotrifluoroethane (HCFC133a), tetrafluoroethane (HFC134a), monochlorodifluoroethane (HCFC142b) and trifluoroethane (HFC143a).

However, these chlorofluoroalkanes and fluoroalkanes do not satisfy well-balanced ozone depletion potential (hereinafter abbreviated as ODP), refrigerating capacity, coefficient of performance, and other various properties required as a refrigerant. .

Attempts have also been made to mix fluoroalkanes. In JP-A-1-108291, H
Although a binary mixture of FC125 and HFC134a is disclosed, there is room for improvement in terms of refrigerating capacity.

[0007]

The object of the present invention is to provide excellent properties such as refrigerating capacity, coefficient of performance, discharge gas temperature, etc. required as a refrigerant for a refrigerator, and ozone even when released into the atmosphere. It is to provide a refrigerant that does not affect the formation.

[0008]

As a result of intensive studies to achieve the above object, the present inventor has found that a mixture of specific fluoroalkanes has excellent properties as a refrigerant, and completed the present invention. .

That is, according to the present invention, (1) trifluoromethane (hereinafter referred to as HFC23), (2) pentafluoroethane (hereinafter referred to as HFC125), tetrafluoroethane (hereinafter referred to as HFC134a) and octafluorocyclobutane (hereinafter referred to as HFC134a). Hereinafter, the mixed refrigerant comprising at least one compound selected from the group consisting of FC-C318) is provided.

Of the present invention, (1) HFC23 and (2) HFC
A two-component mixed refrigerant consisting of one selected from FC125, HFC134a and FC-C318 is preferable, and the mixing ratio is usually (1) HFC23 of 5 to 5
0% by weight and (2) HFC125, HFC134a, FC
-One kind selected from C318 is 95 to 50% by weight.
Further, in the present invention, (1) HFC23 and (2) HF
C134a and (3) HFC125 or FC-C318
A three-component mixed refrigerant composed of and is particularly preferable, and the mixing ratio thereof is (1) HFC23 5-40 wt% and (2) HFC134a 95-20 wt% (3).
Either HFC125 or FC-C318 is 40 wt% or less.

The above-mentioned preferable mixing ratio of the mixed refrigerant of the present invention is appropriately selected in consideration of physical properties such as boiling point, critical temperature and latent heat of vaporization of each component. For example, the HFC 23 improves the refrigerating capacity, but if the ratio becomes too high, the critical temperature of the mixed refrigerant becomes low and the vapor pressure becomes high, and the cycle efficiency decreases. The HFC 125 has an effect of lowering the discharge gas temperature, but if the ratio is high, the latent heat of vaporization becomes small and the refrigeration cycle efficiency decreases. FC-C318 has an effect of lowering the discharge gas temperature, but if the ratio is high, the boiling point becomes high, so that the refrigerating capacity of the refrigerant is lowered, and the latent heat of vaporization is also small, so the cycle efficiency is also lowered.

HFC23, HFC12 used in the present invention
5, the structures of HFC134a and FC-C318 are as shown below.

[0013]

[Chemical 1]

If desired, a stabilizer may be used in combination with the mixed refrigerant of the present invention. That is, when a high degree of stability is required under severe conditions of use, epoxides such as propylene oxide, 1,2-butylene oxide and glycidol; phosphites such as dimethyl phosphite, diisopropyl phosphite and diphenyl phosphite. Phytes; thiophosphites such as trilauryltrithiophosphite; phosphine sulfides such as triphenoxyphosphine sulfide and trimethylphosphine sulfide; boron compounds such as boric acid, triethylborate, triphenylborate, phenylboronic acid and diphenylboronic acid Phenols such as 2,6-di-tert-butylparacresol; nitroalkanes such as nitromethane and nitroethane; acrylic acid esters such as methyl acrylate and ethyl acrylate; Other stabilizers such as dioxane, tert-butanol, pentaerythritol, and paraisopropenyltoluene may be added in an amount of about 0.01 to 5% by weight based on the weight of the mixture.

Further, other compounds can be mixed with the mixed refrigerant of the present invention within a range not impairing the objects and effects of the present invention. Such compounds include ethers such as dimethyl ether and pentafluorodimethyl ether; amines such as perfluoroethylamine; LPG
Are exemplified.

Further, the mixed refrigerant of the present invention is suitable as a foaming agent or a propellant since it has non-flammability in addition to having an ODP of zero.

[0017]

The mixed refrigerant of the present invention has the following effects.

Since the mixed refrigerant of the present invention is easily decomposable and does not contain chlorine atoms and bromine atoms that affect the ozone layer, there is no danger of causing ozone layer destruction problems.

Further, the mixed refrigerant of the present invention is HFC2
3, HFC125, HFC134a and FC-C31
It is more balanced in various properties required as a refrigerant for a refrigerator, such as refrigerating capacity, coefficient of performance, discharge gas temperature, etc.

Further, since the mixed refrigerant of the present invention has low solubility in a polymer compound and is nonflammable, it can be used as it is in a conventional refrigerator.

Due to these characteristics, it is excellent as a substitute for R502 containing CFC115 which is subject to the above-mentioned international regulation.

[0022]

EXAMPLES Examples and comparative examples will be shown below to further clarify the features of the present invention.

In FIGS. 1 and 2, the upper, middle, and lower three numerical values show the refrigerating capacity (kcal / m ³ ) in the upper part, the coefficient of performance in the middle part, and the discharge gas temperature (° C.) in the lower part. .

[0024]

Example 1 As a refrigerant, H shown as a triangular chart in FIG.
2 consisting of FC23, HFC125 and HFC134a
In a refrigerator using a three-component or three-component mixed refrigerant,
The operation was performed with the evaporation temperature of the refrigerant in the condenser set to -75 ° C, the condensation temperature set to -25 ° C, the superheat temperature set to 0 ° C, and the condenser subcooling degree set to 5 ° C.

Note that R502 and R currently in general use
The refrigerating capacity, the coefficient of performance, and the discharge gas temperature (° C.) under the conditions of No. 22 are shown in Table 1 below.

Table 1 R502 R22 Refrigerating capacity (kcal / m ³ ) 47.3 38.1 Coefficient of performance 3.4 3.2 Discharge gas temperature (° C) 0 36 The results are shown in FIG.

[0027]

Example 2 As a refrigerant, H shown as a triangular chart in FIG.
The refrigerator was operated in the same manner as in Example 1 except that the two-component or three-component mixed refrigerant composed of FC23, FC-C318 and HFC134a was used.

The results are shown in FIG.

[Brief description of drawings]

1 is a composition ratio of a mixed refrigerant according to the present invention, a refrigerating capacity,
It is a triangular chart showing the relationship between the coefficient of performance and the discharge gas temperature. The preferable composition range of the three-component mixed refrigerant is shown by the shaded area in the figure.

2 is a composition ratio of a mixed refrigerant according to the present invention, a refrigerating capacity,
It is a triangular chart showing the relationship between the coefficient of performance and the discharge gas temperature. The preferable composition range of the three-component mixed refrigerant is shown by the shaded area in the figure.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsuki Fujiwara             Daiichi Nishiichitsuya 1-1, Settsu City, Osaka Prefecture             Yodogawa Manufacturing Co., Ltd. (72) Inventor Hiroshi Momota             Daiichi Nishiichitsuya 1-1, Settsu City, Osaka Prefecture             Yodogawa Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. A mixed refrigerant comprising (1) trifluoromethane and (2) at least one compound selected from the group consisting of pentafluoroethane, tetrafluoroethane and octafluorocyclobutane. 2. A mixed refrigerant comprising (1) trifluoromethane, (2) tetrafluoroethane, and (3) any one compound of pentafluoroethane and octafluorocyclobutane.