JP2003268357A - Hydrocarbon coolant and air conditioner for automobile using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a coolant which exhibits excellent performances equal to those of Freon (R) hitherto employed without destroying the ozone layer of the earth, and an air conditioner for an automobile using the same. <P>SOLUTION: A hydrocarbon mixture comprising dimethyltrifluoroethane and propane is used as a coolant. Preferably, the mixing ratio is such that dimethyltrifluoroethane accounts for 5-95 wt.% and propane accounts for 95-5 wt.%. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant used in an air conditioner for an automobile, and an air conditioner for an automobile using the refrigerant.

[0002]

2. Description of the Related Art Conventionally, hydrocarbon compounds containing chlorine and fluorine such as fluorodichloromethane and difluorochloroethane have been widely used as refrigerants since the 1930s as so-called CFCs. These compounds have been widely used because they are relatively stable, less corrosive to metals, safe and inexpensive. That is, monochlorodifluoromethane and the like have been used for home air conditioners and the like. On the other hand, in fields that require low temperatures of -40 to -60 degrees Celsius,
Monobromotrifluoromethane with a boiling point of -57.8 ° C, a mixture of monochlorodifluoromethane and monochloropentafluoroethane, etc. have been used. However, these hydrocarbons containing chlorine and bromine are not completely decomposed on the ground, and when they reach the ozone layer, they may react with ozone in the ozone layer to reduce ozone and adversely affect terrestrial organisms. It has been pointed out that it is also related to global warming.

The ozone layer is formed in the so-called stratosphere of the earth and has a function of absorbing harmful ultraviolet rays from the sun. If such an ozone layer is destroyed, there is a danger that it will have a serious adverse effect on the survival of organisms including humans. It has already been observed that the ozone layer has disappeared in Antarctica, and such fears may become a reality.

For this reason, attempts have been made to regulate the use of such harmful CFCs, which has become an internationally urgent issue, and the development of CFC substitutes is urgent.

Conventionally, fluorocarbons that have been widely used have chlorine and fluorine in the molecule, but it has been clarified that chlorine is involved in the reaction with ozone. That is, it has been found that chlorine molecules or free radicals generated from chlorine are likely to destroy ozone. On the contrary, it is said that fluorine or free radicals generated from fluorine do not relatively destroy ozone. The ozone depletion potential of an ozone depleting substance is a sequence of elements contained in the substance (F <Cl <B
It is understood that the reason determined by r) reflects the stability order of the produced hydrogen halide (high stability HF>HC1> HBr low stability).

A compound containing no halogen such as chlorine and fluorine (eg, propane) is safer against destruction of the ozone layer, but has a problem in safety and performance such as flammability.

In view of the present situation, various developments have been made in the past, and countermeasures such as making a hydrocarbon containing fluorine or a mixture of a hydrocarbon containing fluorine and a hydrocarbon such as propane have been tested. For example, JP-A-8-41449 proposes a pentafluoroethane-propane mixed refrigerant. In this method, the boiling point range is -40
It is intended to be used as a refrigerant for commercial equipment such as environmental testing machines and freezers in the range of -60 ℃, and is not intended for general use such as household air conditioners. Therefore, for general use, there are disadvantages such as the high fluorine content of pentafluoroethane and the economical disadvantage. In many cases, the CFC substitute is inferior in performance as a refrigerant and has not been widely put into practical use.

[0008]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a refrigerant which is remarkably excellent in flame retardancy, ozone depletion, and performance as a refrigerant.

That is, the present invention is as follows. 1. A hydrocarbon-based refrigerant composed of dimethyltrifluoroethane and propane. 2. A hydrocarbon-based refrigerant composed of 5-95% dimethyltrifluoroethane and 95% -5% propane. 3. A hydrocarbon-based refrigerant composed of 65 to 70% of dimethyltrifluoroethane and 35 to 30% of propane, Dimethyltrifluoroethane 67.5-68.5
%, Propane 32.5 to 31.5% hydrocarbon-based refrigerant, An air conditioner for an automobile, which uses the hydrocarbon-based refrigerant described in 1 to 4 above.

[0010]

Each means of the present invention will be described below.

Examples of dimethyltrifluoroethane used in the present invention include 1,1-dimethyl-2,2,2-trifluoroethane, 1,1-dimethyl-1,2,2-trifluoroethane, and 2-methyl. -1,2,3-Trifluoropropane and 2-methyl-1,3,3-trifluoropropane can be mentioned. In addition, examples of propane used in the present invention include n-propane and 2-methylethane.

The mixture of dimethyltrifluoroethane and propane of the present invention exists as a liquid at normal temperature under pressure. It is easily obtained by weighing and mixing predetermined amounts of each component, and stored in a sealed stainless steel container. At the time of use, it can be easily given a function as a refrigerant by injecting it into a machine such as a refrigerator or an air conditioner.

In the present invention, dimethyltrifluoroethane 65 to 70%, propane 30 to 35%, more preferably dimethyltrifluoroethane 67.5 to 68.5.
%, The reason for limiting to 32.5-31.5% propane is
This is because excellent performance is exhibited in this range. Next, examples will be given to explain the present invention in more detail.

[0014]

[Embodiment 1] A sample gas cylinder is connected to a closed container cooled by a cooler, and a vacuum pump is connected between them. First, the air in the entire system is removed by a vacuum pump, and then the sample gas is filled. The filling amount is calculated from the weight change of the sample gas cylinder. In this way, dimethyltrifluoroethane 68
Parts by weight (hereinafter referred to as "parts") and 32 parts of propane were mixed and filled in a 360 ml capacity closed container 100 g each to obtain a product. This mixture exhibited the following properties. Physical properties 1. Boiling point (℃) -30.68 2. Vapor pressure at 25 ℃ (KPa) 507.3 3. Vapor pressure at 35 ℃ (Kpa) 781.0 4. Explosion limit (volume%) 2.02 to 9.1 5. Density (25 ℃) (g / m3) 597.13 Safety 6. Ozone-Depletion Potential (ODP) 0 7. Global Warning Potential (GWP) 0 The analysis test results are as follows. Water content: 0.005% (maximum) Acid content: 0.0001% (maximum)

[0015]

[Example 2] The mixed refrigerant of Example 1 was connected to an automobile air conditioner through a pressure resistant tube, and 400 g was press-fitted. It was 20 when the air temperature of 35 ℃ was sent in and the outlet temperature of the air conditioner was measured.
It was confirmed that the refrigerant of the present invention was operating effectively by delivering the air of ℃. Furthermore, it operated without any problem in the continuous operation test for 8 to 10 hours, and the effectiveness of the refrigerant of the present invention was confirmed.

[0016]

Since the composition of the present invention does not contain chlorine atoms, it does not decompose ozone by reacting with ozone, and since it uses a compound containing fluorine atoms, it has excellent flame retardancy. In addition, the performance as a refrigerant is equivalent to that of the conventionally used CFCs.

The composition of the present invention can be widely used in automobile air conditioners, household air conditioners, etc. because of the above-mentioned excellent performance.
And since it is non-polluting, it meets the needs of society and its industrial significance is extremely large.

Claims (5)

[Claims] 1. A hydrocarbon refrigerant comprising dimethyltrifluoroethane and propane. 2. A hydrocarbon-based refrigerant comprising 5 to 95% by weight of dimethyltrifluoroethane (hereinafter referred to as%) and 95% to 5% of propane. 3. Dimethyltrifluoroethane 65-70%
A hydrocarbon-based refrigerant consisting of 35 to 30% of propane. 4. Dimethyltrifluoroethane 67.5-6
A hydrocarbon-based refrigerant composed of 8.5% and propane 32.5 to 31.5%. 5. A vehicle air conditioner using the hydrocarbon-based refrigerant according to any one of claims 1 to 4.