JPH06220435A - 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, 1,1,1,2- tetrafluoroethane, and carbon dioxide 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 [1:85:14], [1:93:6], [35:64:1], [44:55:1], and [44:51:5].

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 to be mixed (for example, JP-A-3-287688). 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), 1,1,1,2-tetrafluoroethane (CF ₃ CH ₂ F, hereinafter “HFC1”).
34a ”) and carbon dioxide (CO ₂ , hereinafter“ C ”).
O ₂ )), wherein when the mol% of each component on the triangular coordinate system having 100 mol% of the above-mentioned components as apexes is expressed in the above order, the mol% of each component is [1; 14 ;, [1; 93; 6], [35; 6
4; 1], [44; 55; 1], and [44; 51;
[5] The problem can be solved by providing a refrigerant composition within the range of a polygon having each point as an apex. The refrigerant composition provided herein is hereinafter referred to as "refrigerant composition R". In the above, the mol% of each component is [1; 85; 1
4], [1; 93; 6], [26; 72; 2], and [40; 54; 6] are preferably in the range of a polygon having vertices at the respective points. The refrigerant composition having this composition is hereinafter referred to as "refrigerant composition S". The composition range of the refrigerant composition S is included in the composition range of the refrigerant composition R.

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. Furthermore, since any refrigerant composition contains CO ₂ containing no hydrogen atom as a component, it 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. The coordinates, the HFC32, and the HFC134a, respectively apex 100 mole% of CO _2, respectively next counterclockwise for each vertex, a line segment representing a 0-100 mole% of the vertex component and one side It is composed of regular triangles. An arbitrary point X (not shown) in this coordinate is a straight line including the point X and parallel to the side (HFC134a).
The point that intersects with the component HFC32 is mol%, the point where a straight line including the point X and parallel to the side (CO ₂ ) intersects with the side (HFC134a) is the mol% of the component HFC134a, and includes the point X and is parallel to the side (HFC32). The point where a straight line intersects the side (CO ₂ ) is defined as mol% of the component CO ₂ , and [HFC32; HFC1
34a; CO ₂ ], in the order of mol% of each component.

In FIG. 1, the refrigerant composition R is indicated by a point A.
[1; 85; 14], point B [1; 93; 6], point C [3
5; 64; 1], point D [44; 55; 1], and point E.
It has a composition represented by any one point within the range of a polygon having each point of [44; 51; 5] as vertices.
Of the components of the refrigerant composition R, HFC32, HFC134
a contains no halogen other than fluorine, and CO ₂ contains no halogen atom. Each of these components has an ozone depletion potential of 0
And the ozone depletion potential of any mixture of these components is zero. 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. Line AE shows the isothermal isotherm of a composition having a vapor pressure of 28 kgf / cm ² G at 55 ° C. For use as an alternative refrigerant for the HCFC22, for example CO ₂ is 1
The composition is selected to be 4 to 5 mol% or less. Also line B
C shows an isotherm isotherm of a composition having a vapor pressure of 2 kgf / cm ² G at -15 ° C, and for use as an alternative refrigerant of HCFC22, for example, CO ₂ is 6 to
The composition is selected to be 1 mol% or more.

The line DE shows the critical composition which makes the refrigerant composition R nonflammable. This critical composition is obtained by mixing HFC32 with various hydrofluorocarbons or various fluorocarbons and measuring the combustion range, and as a result, if the number of hydrogen atoms contained in the gas is the number of fluorine atoms × 0.64 or less, the gas is It was obtained as a result of finding out the fact that it shows nonflammability, and since HFC32 is flammable by itself, the composition contains CO ₂ which is nonflammable.
The blending limit of HFC32, which can maintain nonflammability, is higher than that of the composition containing only hydrofluorocarbons.

Lines AB and CD are HFC32 and CO which allow a wide selection of three component compositions as refrigerant composition R.
The lower limit of the mixing ratio of each of ₂ and is shown. That is, in this three component system, the HFC32 and CO ₂ must be contained 1 mol% or more either. Under this condition, the refrigerant composition R as an alternative refrigerant for HCFC22
The degree of freedom in selecting the composition 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 points A [1; 85; 14] and points B [1; 9].
3; 6], point F [26; 72; 2], and point E [40;
54; 6], and has a composition represented by any one point within the range of a polygon having vertices at each point. 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 AE and BF 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 AE has a temperature of 55 ° C and a vapor pressure of 28 kgf / cm.
^It is an isothermal isobaric line showing ² G, and line BF is -15 ° C, 2k.
Isothermic isobaric lines showing gf / cm ² G. Also, line AB
Is the same as line AB in FIG. 1 and indicates that HFC32 should be at least 1 mol% in this ternary system.

Line EF shows the composition of the liquid in equilibrium with the vapor having the composition shown at any one point on line DE in FIG. That is, if the concentration of HFC32 is lower than the composition indicated by the point on the line EF, the composition is inflammable not only in liquid but also in vapor in equilibrium therewith.

[0017]

EXAMPLES Examples of the present invention will be described below. Example 1 Example 1 was prepared by mixing HFC32, HFC134a and CO _{2 in} the proportions of 10 mol%, 80 mol% and 10 mol%, respectively. (Example 2) HFC32, HFC134a, and FC218
And were mixed in the proportions of 20 mol%, 75 mol% and 5 mol%, respectively, to obtain Example 2. (Comparative Example) HCFC22 was used as a comparative example.

(Ozone Depletion Coefficient) The compositions of Examples 1 and 2 have HFC32 and HFC134a containing no halogen atom other than fluorine, and CO ₂ containing no halogen atom, and thus have an ozone depletion coefficient of 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, 1,1,1,2-tetrafluoroethane, and carbon dioxide, wherein the mol% of each component in triangular coordinates is the above. [1; 85; 14], [1;
93; 6], [35; 64; 1], [44; 55;
1] and [44; 51; 5] are within the range of the polygon with each point as the apex, it does not destroy the ozone layer in the stratosphere even if it is released into the atmosphere, 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 ... Each composition point of the three-component system.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Kiyomitsu Kanno 1-13-9 Shibadaimon, Minato-ku, Tokyo Within Showa Denko KK

Claims (2)

[Claims] 1. A refrigerant composition comprising difluoromethane, 1,
When 1,1,2-tetrafluoroethane and carbon dioxide are included and the mol% of each component in the triangular coordinate system having 100 mol% of the above component as the vertex is represented in the above order,
The mol% of each component is [1; 85; 14], [1; 93;
6], [35; 64; 1], [44; 55; 1], and [44; 51; 5] within a polygon having vertices at respective points. Composition. 2. In the above, the mol% of each component is [1;
85; 14], [1; 93; 6], [26; 72;
2] and [40; 54; 6] are within the range of a polygon having vertices at the respective points, The refrigerant composition according to claim 1.