JPH0762335A - Refrigerant composition - Google Patents

Abstract

PURPOSE:To obtain a refrigerant composition which does not cause ozonosphere depletion, can substitute for conventional refrigerants without changing the existing equipment and is noncombustible. CONSTITUTION:This composition comprises difluoromethane, pentafluoroethane and octafluoropropane and has a chemical composition in the range within the polygon having the vertices of the coordinates [59;1;40], [20;1;79], [1;30;69], [1;98;1] and [15;84;1] in terms of the molar percentages of the respective components in the above given order in the triangular diagram.

Description

Detailed Description of the Invention

[0001]

This invention relates to refrigerant compositions. In particular, the present invention relates to a refrigerant composition that can be used as an alternative refrigerant for chlorodifluoromethane without modifying existing equipment.

[0002]

2. Description of the Related Art Conventionally, fluorine-containing halogenated hydrocarbons such as chlorofluorocarbons, hydrochlorofluorocarbons, fluorocarbons, hydrofluorocarbons or mixtures thereof have been used as refrigerants for cooling devices such as air conditioners and refrigerators. ing. In particular, chlorodifluoromethane (CHClF ₂ , hereinafter “H
CFC22 ") is widely used as a refrigerant for home air conditioners, building air conditioners, large refrigerators, and the like.

In recent years, depletion of the ozone layer in the stratosphere due to chlorofluorocarbons has become a serious problem. Hydrochlorofluorocarbons such as HCFC22 have an extremely small ozone depletion potential compared to chlorofluorocarbons, but if the amount used is increased, the possibility of depleting the ozone layer also increases, so their production and use are It has come to be subject to international regulations. Therefore, HCFC that can be used as it is in conventional cooling devices without affecting the ozone layer
22 There is a strong international demand for the development of alternative products. Hydrofluorocarbons are not subject to regulation because they do not have the potential to destroy the ozone layer. In particular, difluoromethane (CH ₂ F ₂ , hereinafter referred to as “HFC32”) has an ozone depletion potential of 0 and a small global warming potential,
Further, since it has a relatively excellent refrigerating capacity, it is considered to be a promising refrigerant for industrial use, particularly in fields requiring low temperature cooling.

[0004]

However, the HFC32 is
HCFC22 at operating temperature of air conditioners and refrigerators
Since the vapor pressure is higher, there is a problem in that it cannot be used as it is in the existing apparatus dedicated to the HCFC22 because of the pressure resistance of the apparatus. Since changing the pressure resistance of the device is very expensive, there is virtually no possibility of replacement. In addition, air conditioners and the like are widely used in general homes and offices, and the alternative refrigerant used must be a nonflammable substance from the viewpoint of safety.
However, since HFC32 is a flammable substance, there is a problem in that it cannot be easily used as an alternative refrigerant from this point of view.

In attempting to solve the above problems when using HFC32 as an alternative refrigerant to HCFC22, HFC
Attempts have been proposed to mix 32 with other hydrofluorocarbons (eg US Pat. No. 497846).
7). However, although the composition of these proposals solves the problem of ozone depletion, it has a narrow selection range of the composition range that makes the temperature / pressure condition and the nonflammability compatible with each other, and thus the composition can be applied to existing devices. It was difficult. Therefore, HCF
There has been a strong demand for a refrigerant composition that can be put to practical use as an alternative refrigerant for C22. The present invention has been made to solve the above problems.

From this point of view, the conditions required as an alternative refrigerant for the HCFC 22 are as follows. (1) When released into the atmosphere, do not destroy the ozone layer in the stratosphere. (2) It can be used as an alternative to existing equipment that uses HCFC22 as a refrigerant without changing the equipment. That is, it should be possible to use within the allowable range of the cooling capacity and the withstand pressure of the existing equipment. (3) It is nonflammable in a wide composition range. In particular, considering the risk of ignition of leaked steam, it is preferable that the refrigerant, including the equilibrium steam of the refrigerant, be non-flammable. Therefore, an object of the present invention is to provide an HCF satisfying all the above conditions.
It is to provide an alternative refrigerant composition of C22.

[0007]

[Means for Solving the Problems] The above problems are solved by difluoromethane (“HFC32” above), pentafluoroethane (CF ₃ CHF ₂ , hereinafter referred to as “HFC125”), and octafluoropropane (CF ₃ CF ₂ CF).
₃ , hereinafter referred to as “FC218”), wherein when the mol% of each component in the triangular coordinate system having 100 mol% of the above components as the vertex is represented in the above order, the mol% of each component is [ 59; 1; 40], [20; 1; 7
9], [1; 30; 69], [1; 98; 1], and [15; 84; 1], provided with a refrigerant composition within the range of a polygon having each point as an apex. It can be solved by The refrigerant composition provided herein is hereinafter referred to as "refrigerant composition R".

The refrigerant composition R of the present invention does not destroy the ozone layer in the stratosphere even when it is released into the atmosphere. Further, any of the refrigerant compositions can be used as a substitute for an existing device that uses HCFC22 as a refrigerant without changing the device. Furthermore, since any refrigerant composition contains FC218 that does not contain hydrogen atoms as a component, not only the composition but also its equilibrium vapor are nonflammable over a wide composition range.

Next, the refrigerant composition of the present invention will be described in detail with reference to the drawings. FIG. 1 is triangular coordinates showing the composition range of the refrigerant composition R. These coordinates are HFC32 and H
Each of FC125 and FC218 has an apex with 100 mol% as the apex, and adjacent to each apex in the counterclockwise direction is a regular triangle with one side representing a line segment representing 0 to 100 mol% of the apex component. An arbitrary point X (not shown) in this coordinate is defined as a point where a straight line including the point X and parallel to the side (HFC125) intersects with the side (HFC32) as the mol% of the component HFC32. The point where the straight line parallel to (FC218) intersects the side (HFC125) is defined as mol% of the component HFC125, and the point where the straight line including the point X and parallel to the side (HFC32) intersects the side (FC218) is defined as the mol% of the component FC218. , [HFC32; HFC125; FC218], in the order of mol% of each component.

In FIG. 1, the refrigerant composition R is indicated by a point A [5
9; 1; 40], point B [20; 1; 79], point C [1;
30; 69], point D [1; 98; 1], and point E [1
5; 84; 1] and has a composition represented by any one point within the range of a polygon having each point as a vertex. Neither component of the refrigerant composition R contains halogen other than fluorine. Each of these components has an ozone depletion potential of 0, and any mixture of these components also has an ozone depletion potential of 0. Therefore, the refrigerant composition R does not destroy the ozone layer in the stratosphere. Lines AE and BC in FIG. 1 indicate composition limits for satisfying the temperature / pressure conditions required when the refrigerant composition R is used as a substitute for the existing cooling device dedicated to the HCFC 22.

Generally, in a cooling device including a compressor, a temperature / pressure condition for compressing and liquefying a refrigerant vapor and a temperature / pressure condition for vaporizing a liquefied refrigerant must be satisfied. . In the cooling device dedicated to the HCFC22, the maximum temperature during compression is 55 ° C, and the vapor pressure at this time is 28 kgf / cm ² G. The vaporization temperature is -15 ℃, and the saturated vapor pressure is 2kgf / cm.
It is ² G. Therefore, the refrigerant composition R must satisfy this condition. That is, the refrigerant composition R is 55
Vapor pressure at 28 ° C is 28 kgf / cm ² G or less, -15
It is selected from those having a saturated vapor pressure at 2 ° C of 2 kgf / cm ² G or more. Line AE shows a vapor pressure of 28 kgf / cm ² at 55 ° C.
2 shows the isotherm isotherm of a composition showing G, HCFC2
2 For use as a substitute refrigerant, for example, a composition in which FC218 is in this line, that is, 40 to 1 mol% or more is selected.

Line BC has a vapor pressure of 2 kgf / at -15 ° C.
The isothermal isotherm of a composition showing cm ² G is shown as HCF
To use as a C22 alternative refrigerant, for example, FC218
The composition is selected so that this line, that is, 79 to 69 mol% or less. Lines AB, CD and DE show the lower limit of the blending ratio of HFC32 which allows a wide selection of three component compositions as the refrigerant composition R. That is, in this three-component system, HFC125, HFC32, and FC218 must all be contained in an amount of 1 mol% or more. This condition increases the degree of freedom in selecting the composition of the refrigerant composition R as the HCFC22 alternative refrigerant.

Refrigerant composition R exhibits full range nonflammability. In this composition range, HFC32 is mixed with various hydrofluorocarbons or various fluorocarbons,
As a result of actually measuring the combustion range, if the number of hydrogen atoms contained in the gas is less than or equal to the number of fluorine atoms × 0.64, it was obtained as a result of finding the fact that the gas exhibits noncombustibility, and the HFC32 alone Is flammable, the composition contains FC218, which is nonflammable. Therefore, the blending limit of HFC32 capable of maintaining nonflammability is higher than that of the composition containing only hydrofluorocarbons. In addition, the refrigerant composition R is nonflammable not only in liquid but also in vapor in equilibrium with it over the entire range.

[0014]

EXAMPLES Examples of the present invention will be described below. (Example 1) HFC32, HFC125, and FC218 were mixed in the proportions of 30 mol%, 20 mol%, and 50 mol%, respectively, to obtain Example 1.

Example 2 Example 2 was prepared by mixing HFC32, HFC125 and FC218 in the proportions of 20 mol%, 50 mol% and 30 mol%, respectively.

(Comparative Example) HCFC22 was used as a comparative example.

(Ozone Depletion Coefficient) The compositions of Examples 1 and 2 contain no halogen atom other than fluorine in any of the components thereof, and thus the ozone depletion coefficient is 0. (Temperature / Vapor Pressure Conditions) The vapor pressures at −15 to 55 ° C. of the compositions of Examples 1 and 2 were measured. The vapor pressure was measured by charging a certain amount of the composition into a measuring cylinder, stirring and leaving the composition at a predetermined temperature, and then reading the pressure when the pressure became stable. The results are shown in Table 1. In addition, Table 1 also shows the literature values of Comparative Examples.

Flammability The compositions of Examples 1 and 2 were tested for flammability. The flammability test method was as follows. The composition was sealed together with air in a cylindrical container having a spark electrode and a capacity of about 1.5 liters, a voltage of 15 kV was applied to generate an electric spark, and the presence or absence of flame propagation was observed. The case where no ignition phenomenon was observed at any air concentration was judged as "non-combustible". The results are shown in Table 1.

[0019]

[Table 1]

The above results are summarized as follows. (1) Neither Example 1 nor Example 2 destroys the ozone layer in the stratosphere. (2) In Examples 1 and 2, the vapor pressure at -15 ° C is 2 kgf / cm ² G or more, and the vapor pressure at 55 ° C is 28 kgf / cm ² G or less. That is, all of them satisfy the condition that they can be used as a substitute refrigerant for the HCFC 22 without changing the device. (3) Both Examples 1 and 2 are nonflammable. Therefore, it is clear that the compositions of Examples 1 and 2 are refrigerant compositions that can be used as alternative refrigerants for HCFC22.

[0021]

The refrigerant composition of the present invention is a composition containing difluoromethane, pentafluoroethane, and octafluoropropane, and the mol% of each component in triangular coordinates is [59; 1] in the above order. 40], [20;
1; 79], [1; 30; 69], [1; 98; 1],
And [15; 84; 1] are within the range of the polygon with each point as the apex, so even if it is released into the atmosphere, it does not destroy the ozone layer in the stratosphere, and chlorodifluoromethane It can be used as an alternative to existing equipment used as a refrigerant without modification of the equipment, and is nonflammable over a wide composition range.

[Brief description of drawings]

FIG. 1 is a triangular coordinate showing a composition range of a refrigerant composition of the present invention.

[Explanation of symbols]

 A, B, C, D, E composition point of each three-component system

Claims (1)

[Claims] 1. When the refrigerant composition contains difluoromethane, pentafluoroethane and octafluoropropane, and when the mol% of each component on the triangular coordinate system having 100 mol% of the above components as the apex is expressed in the above order, each component [59; 1; 40], [20; 1; 79],
[1; 30; 69], [1; 98; 1] and [15; 8
4; 1] is within the range of a polygon having each point as an apex.