JPH11199863A - Mixed working fluid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mixed working fluid capable of minimizing its effect on the earth warming and becoming a substitute for R12 with only slight affection on ozonosphere in the stratosphere by using butane, trifluoroiodomethane and difluoroethane in a specific mixing ratio. SOLUTION: This mixed working fluid is composed of <=10 wt.% of butane (R600) or isobutane (R600a) and trifluroiodomethane (CF3 I) and 1,1-difluoroethane (R152a). The fluid is obtained by further adding and mixing the CF3 I not containing chlorine as an explosion countermeasure when mixing the R152a not containing chlorine with a hydrocarbon such as the R600 or the R600a, and is useful as a coolant of a cooling cycle device such as a refrigerator or a freezer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed working fluid used as a refrigerant in a refrigeration cycle device such as a refrigerator and a refrigerator.

[0002]

2. Description of the Related Art Conventionally, a refrigerating cycle device such as a refrigerator and a refrigerator is connected to a compressor, a condenser, a throttle device such as a capillary tube and an expansion valve, an evaporator, an accumulator, and a four-way valve used as necessary. Then, a cooling or heating action is performed by circulating a coolant inside the inside. In these refrigeration cycle apparatuses, halogenated hydrocarbons derived from methane or ethane, called chlorofluorocarbons (hereinafter referred to as ROO or ROO), have been used as refrigerants.

[0003] In a refrigerator, a refrigerator or the like, a utilization temperature is usually about 40 ° C. for a condensing temperature and about −30 ° C. for an evaporating temperature.
It is in the range of -40 ° C. And, R12 (dichlorodifluoromethane CCl ₂ F ₂ , boiling point −29.7 ° C.) has been widely used as a refrigerant. However, in recent years, stratospheric ozone depletion due to chlorofluorocarbon has become a global environmental problem, and its use and production have already been abolished by the Montreal International Treaty because of its stratospheric ozone depletion potential (ODP).
For this reason, in order to reduce the influence on the stratospheric ozone layer at present, R134a (1,1,1,2-tetrafluoroethane CF ₃ —CH ₂₎ , which is a fluorinated hydrocarbon containing no chlorine in the molecular structure, is used. F, boiling point −26.1 ° C.)
Since the boiling point is close to 2, it is used as a substitute refrigerant for R12.

[0004]

However, fluorocarbon refrigerants have a relatively large global warming potential (hereinafter referred to as GWP), which indicates the effect on global warming, which is another environmental problem. Have been. 1995 I
PCC (Intergovernmental Panel on ClimateChange,
The Intergovernmental Panel on Climate Change reports that carbon dioxide (CO
₂ ) When the GWP is set to 1, the comparison value of the integrated horizontal axis for 100 years is as follows: GWP of R12 is 8500, and among fluorinated hydrocarbons containing no chlorine, GWP of R134a is 1300.
It has been. Therefore, although the GWP of R134a is reduced to about 1 / 6.5 of R12, further reduction is desired from the viewpoint of global warming.

[0005] Refrigerants of fluorocarbons such as R134a have poor compatibility with synthetic oils such as paraffinic and naphthenic mineral oils and some alkylbenzene oils which have been used as conventional lubricating oils for compressors. For this reason, the lubricating oil discharged together with the refrigerant from the compressor may not return from the low-temperature evaporator to the compressor. Therefore, R134a
When fluorocarbons such as are used as refrigerants, ester oils having good compatibility are generally used as lubricating oils for compressors in new products. However, ester oils are susceptible to hydrolysis and require careful attention to chemical reliability.

[0006] In view of the above problems, an object of the present invention is to provide a working fluid that has almost no effect on the stratospheric ozone layer and can reduce the effect on global warming as an alternative to R12. .

[0007]

According to the present invention, when mixing chlorine-free 1,1-difluoroethane with a hydrocarbon of R600 (butane) or R600a (isobutane), a chlorine-free trichloride is used as an explosion-proof measure. Provided is a mixed working fluid further mixed with fluoroiodomethane. That is, the mixed working fluid of the present invention is characterized by comprising 10% by weight or less of butane or isobutane, trifluoroiodomethane, and 1,1-difluoroethane.

1,1-difluoroethane (R152a,
CHF ₂ —CH ₃ , boiling point −24.0 ° C.) has two carbon atoms and two
Since it is composed of one fluorine atom and four hydrogen atoms and does not contain chlorine in its molecular structure, it has almost no ozone destruction ability.
R152a is weakly flammable, but the GWP of R152a is 140, which can be reduced to about 1/9 of R134a.

R600 (butane nC ₄ H ₈ , boiling point -0.5
° C.) and R600a (isobutane _{(CH 3) 2 -CH-CH} 3, boiling point -1
(1.8 ° C.) hydrocarbons have almost no ozone depleting ability and GWP is almost zero. Also, its chemical structure is close to that of mineral oil and some synthetic oils, so it has good compatibility. The refrigerant obtained by mixing hydrocarbons with R152a fluorinated hydrocarbons in a small amount is a conventional lubricant for compressors other than ester oil. It can be used with oil. Where R600 (butane) and R600a (isobutane)
Produced an azeotropic mixture with R152a. In particular, those having a mixing amount of hydrocarbons of 10% by weight or less can be handled as a substantially azeotropic mixture while improving the compatibility with the lubricating oil.

Trifluoroiodomethane (CF ₃ I, boiling point-
22.7 ° C.) is also called iodotrifluoromethane or trifluoromethyl iodide, which is composed of one carbon atom, three fluorine atoms, and one iodine atom, and contains no chlorine in its molecular structure. Almost no ozone depletion ability. Further, the GWP of CF ₃ I is almost zero, and as the mixing amount of CF ₃ I increases, R15 further increases.
GWP of 2a can be reduced. CF ₃ I
Is attracting attention as a non-combustible substance having a negative catalytic effect, and can reduce the flammability of hydrocarbons and R152a and can be made non-combustible depending on the mixing amount. Further, the hydrocarbons can be used together with a compressor lubricating oil other than the ester oil without impairing the compatibility with the mineral oil and some synthetic oils. What should be particularly noted here is that R152a forms an azeotropic composition with R152a.
Or R600a, CF ₃ 3-component mixing the working fluid obtained by mixing I also is that the most azeotrope-like mixture.

The mixed working fluid of the present invention can be used not only as a new refrigerant but also as a retrofit refrigerant. Then, it can be used as it is in an ordinary refrigeration cycle device together with a conventional compressor lubricating oil as well as the ester oil. When the mixed working fluid is used together with a conventional compressor lubricating oil, R600 or R600a is selectively dissolved in the conventional compressor lubricating oil,
R600 or R6 in the circulating composition of the refrigeration cycle device
The proportion of 00a is reduced, further avoiding the danger to flammability.

The present invention provides, by the above-mentioned combination, a fluorine-free hydrocarbon containing no chlorine, a hydrocarbon,
Further, by using a mixture of CF ₃ I (trifluoroiodomethane) as a working fluid, it is possible to almost eliminate the influence on the stratospheric ozone layer. ODP in a specified composition range is also reduced. Expected to be 0.

Further, such a mixture comprises R152a, G
Hydrocarbons with little WP and CF ₃ I
(Trifluoroiodomethane), the effect of mixtures of these on global warming is R
It can be made even smaller than the GWP of 134a or R152a.

[0014]

Embodiments of the present invention will be described below.

<< Embodiment 1 >> Table 1 shows that R600 (butane) or R600a (isobutane) of 10% by weight or less.
And R152a (1,1-difluoroethane) and CF
_It shows the vapor pressure (saturated liquid pressure) at a constant temperature of 0 ° C. for a mixture of various components of two or three components consisting of ₃ I (trifluoroiodomethane).

[0016]

[Table 1]

As can be seen from Table 1, a binary R152a / R600 mixture or R15 containing up to 10% by weight of R600 (butane) or R600a (isobutane).
The 2a / R600a mixture has a higher vapor pressure than the single refrigerant of R152a and has an almost azeotropic mixture composition. Also, 1
Three-component R1 containing 0% by weight or less of hydrocarbons
52a / CF ₃ I / R600 mixture or R152a /
In the CF ₃ I / R600a mixture, for all CF ₃ I and R152a ratios shown in Table 1, R15
The vapor pressure is higher than that of the single refrigerant 2a, and the mixture has an almost azeotropic mixture composition.

Here, 10% by weight or less of R600 (butane) or R600a (isobutane), CF ₃ I, R1
The GWP of the mixed working fluid composed of 52a is almost zero because the GWP of hydrocarbons and CF ₃ I is almost zero.
As the mixing amount of CF ₃ I was increased, R152a
Is reduced to be smaller than the GWP of R134a.

<< Embodiment 2 >> Table 2 shows that the specific composition of R1
The ideal refrigeration performance of a ternary system consisting of a 52a / CF ₃ I / R600 mixture is shown. However, the average condensation temperature is 40
° C, average evaporation temperature -40 ° C, supercooling degree at condenser outlet is 0
deg, the performance when the degree of superheat at the evaporator outlet is 70 deg. The refrigeration capacity does not include the sensible heat in the evaporator outlet superheated area.

[0020]

[Table 2]

As can be seen from Table 2, when the ratio of R600 is fixed at 5% by weight, both the refrigerating capacity and the coefficient of performance are improved over R134a in all three-component systems containing CF ₃ I. Further, the temperature gradient in both the condensation process and the evaporation process is 1 deg or less, and the azeotropic mixture can be handled almost in the same manner as a single refrigerant.

Table 3 shows the R152a / CF ₃ I having a specific composition.
/ R600a shows ideal refrigeration performance of a three-component system comprising a mixture. However, the average condensing temperature is 40 ° C., the average evaporating temperature is −40 ° C., the supercooling degree at the condenser outlet is 0 deg, and the superheat degree at the evaporator outlet is 70 deg. Sensible heat is not included.

[0023]

[Table 3]

As can be seen from Table 3, when the ratio of R600 is fixed at 10% by weight, in all three-component systems containing CF ₃ I, both the refrigerating capacity and coefficient of performance are R134a.
Better than that. In addition, the temperature gradients in the condensation process and the evaporation process are all 1 deg or less, and the azeotropic mixture can be handled almost as a single refrigerant.

[0025]

As apparent from the above description, the following effects can be obtained according to the present invention. (1) The mixed working fluid according to the present invention is an azeotropic mixture, and R134a is used as an alternative refrigerant to R12.
GWP is significantly smaller than that of the above, and both the refrigerating capacity and the coefficient of performance are improved. (2) When the mixed working fluid according to the present invention is used as a refrigerant in a refrigeration cycle apparatus containing a conventional compressor lubricating oil other than ester oil, R600 or R600a is selectively dissolved in the lubricating oil and circulated. Since the proportion of R600 or R600a in the composition is reduced and CF ₃ I is a non-combustible substance having a negative catalytic effect, danger to flammability can be avoided.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuharu Matsuo 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A mixed working fluid comprising 10% by weight or less of butane or isobutane, trifluoroiodomethane, and 1,1-difluoroethane.