JPH06220433A - Refrigerant composition - Google Patents

Abstract

PURPOSE:To obtain a refrigerant compsn. which does not deplete the ozonosphere, can substitute for the conventional refrigerants without the necessity for any change in the existing apparatuses, and is nonflammable. CONSTITUTION:This refrigerant compsn. comprises difluoromethane, pentafluoroethane, and octafluorocyclobutane in such a molar ratio that the points indicating the proportions (in mol %, in the above order) in a triangular coordinate exists in the polygon having vertexes at the points expressed by [75:1:24], [53:1:46], [1:66:33], [1:98:1], and [19:80:1].

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 have no possibility of depleting the ozone layer. Especially difluoromethane (CH ₂ F ₂ , hereinafter “HFC
32) has an ozone depletion potential of 0, a small global warming potential, and a relatively excellent refrigerating capacity, and is therefore considered to be a promising refrigerant for industrial use, particularly in fields requiring low temperature cooling. There is.

[0005]

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 an attempt to solve the above problems when using HFC32 as an alternative refrigerant for HCFC22, HFC32
And other hydrofluorocarbons have been proposed in an attempt to mix them (eg US Pat. No. 4,497,846).
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 difluoromethane (“HFC32” above), pentafluoroethane (CF ₃ CHF ₂ , hereinafter referred to as “HFC125”).
And octafluorocyclobutane (C ₄ F ₈ , hereinafter “C
318 ”), wherein when the mol% of each component is represented in the above order in the triangular coordinate system having 100 mol% of the above components as a vertex, the mol% of each component is [75; 1; 24], [53; 1; 46], [1; 6
6; 33], [1; 98; 1], and [19; 80;
The problem can be solved by providing a refrigerant composition within the range of a polygon having each point represented by [1] as a vertex. The refrigerant composition provided herein is hereinafter referred to as "refrigerant composition R". In the above, the mol% of each component is [62; 19; 1
9], [49; 6; 45], [1; 66; 33],
It is preferably within the range of a polygon having the vertices at the points represented by [1; 98; 1] and [19; 80; 1]. The refrigerant composition having this composition is hereinafter referred to as "refrigerant composition S". The composition range of the refrigerant composition S is the refrigerant composition R
Is included in the composition range.

The refrigerant composition R or S 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. Further, any of the refrigerant compositions contains C318 containing no hydrogen atom as a component, and thus is nonflammable over a wide composition range. In particular, the refrigerant composition S is nonflammable even to its equilibrium vapor.

Next, the refrigerant composition of the present invention will be described in detail with reference to the drawings. 1 and 2 are triangular coordinates showing the composition range of the refrigerant composition R or S, respectively. This coordinate has 100 mol% of HFC32, HFC125, and C318 as vertices, and a line segment representing 0 to 100 mol% of the vertices of each vertex is adjacent to each vertex in the counterclockwise direction. It is composed of triangles. 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 (C318) 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 (C318) is defined as the mol% of the component C318. , [HFC32; HFC
125; C318] in the order of mol% of each component.

In FIG. 1, the refrigerant composition R is indicated by a point A [7].
5; 1; 24], point B [53; 1; 46], point C [1;
66; 33], point D [1; 98; 1], and point E [1
9; 80; 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,
The vapor pressure at this time is 28 kgf / cm ² G. The temperature during vaporization is -15 ° C, and the saturated vapor pressure at this time is 2 kgf / cm ² G. Therefore, the refrigerant composition R must satisfy this condition. That is, the refrigerant composition R has a vapor pressure of 28 kg at 55 ° C.
f / cm ² G or less and a saturated vapor pressure at −15 ° C. of 2 kgf / cm ² G or more. The line AE shows an isothermal isotherm of a composition showing a vapor pressure of 28 kgf / cm ² G at 55 ° C., and for use as an alternative refrigerant for the HCFC22, for example, C318 is set to this line, that is, 24 to 1 mol% or more. Is selected. Further, the line BC shows an isothermal isotherm of a composition showing a vapor pressure of 2 kgf / cm ² G at -15 ° C. For use as an alternative refrigerant for the HCFC22, for example, C318 is this line, that is, 46 to 33 mol%. The following composition is selected.

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, the fact that the gas exhibits noncombustibility is obtained, and the HFC32 is independent. Although it is flammable, since the composition contains C318 which is a fluorocarbon, the blending limit of HFC32 that can maintain nonflammability is higher than that of the composition containing only hydrofluorocarbons.

Lines AB, CD and DE are HFC12 which allow a wide selection of three component compositions as refrigerant composition R.
5, the lower limit of the compounding ratio of HFC32 and C318 is shown. That is, in this three-component system, HFC
125, HFC32, and C318 must all be contained in an amount of 1 mol% or more. By this condition, H
The degree of freedom in selecting the composition of the refrigerant composition R as the CFC22 alternative refrigerant is increasing.

FIG. 2 shows the composition range of the refrigerant composition S whose equilibrium vapor is also nonflammable. In FIG. 2, the refrigerant composition S has a point F [62; 19; 19] and a point G [49;
6; 45], point C [1; 66; 33], point D [1; 9
8; 1] and a point E [19; 80; 1], which has a composition represented by any one point within the range of a polygon having vertices. This composition range is included in the composition range of the refrigerant composition R. Therefore, the refrigerant composition S does not destroy the ozone layer in the stratosphere.

Lines EF and CG correspond to lines AE and BC in FIG. 1, and the refrigerant composition S is H
The composition limits for satisfying the temperature / pressure conditions required when used as a substitute for the CFC22 dedicated device are shown.
That is, the line EF has a temperature of 55 ° C. and a vapor pressure of 28 kgf / cm.
Isothermal isobars showing a ² G, line CG is -15 ° C., 2k
Isothermic isobaric lines showing gf / cm ² G. Also, line C
D and DE are the same as the lines CD and DE in FIG.
This ternary system indicates that HFC32 and C318 should be 1 mol% or more.

The line FG represents the composition of the liquid in equilibrium with the vapor having the composition indicated by any one point on the nonflammability limit composition line in this ternary system. That is, if the concentration of HFC32 is lower than the composition shown by the points on the line FG,
The composition is non-combustible not only in liquids, but also in vapors in equilibrium with it.

[0017]

EXAMPLES Examples of the present invention will be described below. (Example 1) HFC32, HFC125, and C318 were mixed at a ratio of 40 mol%, 30 mol%, and 30 mol%, respectively, to obtain Example 1. (Example 2) Example 2 was prepared by mixing HFC32, HFC125, and C318 in the proportions of 20 mol%, 60 mol%, and 20 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 zero. (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. (Combustibility) The compositions of Examples 1 and 2 were tested for combustibility. In the flammability test method, the composition was enclosed together with air in a cylindrical container equipped with a spark electrode, an electric spark of 15 kV was generated, 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 octafluorocyclobutane, and the mol% of each component in triangular coordinates is [75; 24], [5]
3; 1; 46], [1; 66; 33], [1; 98;
1] and [19; 80; 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, It can be used as an alternative to existing equipment that uses difluoromethane as a refrigerant, and it is nonflammable over a wide range of compositions.

[Brief description of drawings]

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

FIG. 2 is triangular coordinates showing a preferable composition range of the refrigerant composition of the present invention.

[Explanation of symbols]

A, B, C, D, E, F, G ... Composition points of ternary system.

Claims (2)

[Claims] 1. When the refrigerant composition contains difluoromethane, pentafluoroethane, and octafluorocyclobutane, and when the mol% of each component in the triangular coordinate system having 100 mol% of the above components as the apex is expressed in the above order, The mol% of the components is [75; 1; 24], [53; 1; 4]
6], [1; 66; 33], [1; 98; 1], and [19; 80; 1] within a polygon having vertices at respective points. Composition. 2. In the above, the mol% of each component is [6
2; 19; 19], [49; 6; 45], [1; 66;
33], [1; 98; 1], and [19; 80; 1] are in the range of a polygon having vertices at the respective points, and the refrigerant composition according to claim 1.