JPH0814675A - Freezer - Google Patents

Abstract

PURPOSE:To avoid serious accident such as fire or explosion or the like under leakage of ignitable refrigerant which becomes a problem when the refrigerant is used by a method wherein hydro-carbon refrigerant enclosed in a freezing cycle is mixed with organic substances containing sulfur such as methylmercaptan and the like. CONSTITUTION:HC refrigerant 17 discharged from a compressor 9 is heat exchanged with surrounding atmosphere at a condensor 10, condensed, liquified and then flowed into a capillary tube 11. The HC refrigerant 17 is reduced in its pressure at the capillary tube 11, evaporated at an evaporator 8, and exchanges exchanges heat with air in an inner box 4. The HC refrigerant 17 here is mixed with an organic substance containing sulfur such as methylmercaptan and the like. Even a small amount of organic substance such as methylmercaptan produces odor, so that even if a small amount of this substance is leaked from a freezing cycle, a leakage of HC refrigerant 17 can be easily detected and so serious accident in which HC refrigerant is ignited and exploded can be avoided.

Description

Detailed Description of the Invention

[0001]

2. Description of the Related Art In recent years, chlorofluorocarbons (hereinafter C
Attention has been focused on environmental problems such as ozone layer depletion and global warming under the influence of FC. From this point of view, the total abolition of CFC, which is a refrigerant, has become an extremely important theme. Currently, CFCs are being converted into hydrochlorofluorocarbons (hereinafter referred to as HCFCs) and hydrofluorocarbons (hereinafter referred to as HFCs), while hydrocarbons that are flammable but have very little impact on global warming (hereinafter referred to as HCs) Is also being developed.

[0002] For example, P of the IIB-IIF Commission B1 / 2 Proceedings in February 1993 in Belgium
281-P291 show that propane (R290) and isobutane (R600a), which are HC, can be applied to a household refrigerator.

An HC refrigerator, which is one of such refrigerating apparatuses, will be described below with reference to the drawings.

FIG. 3 is a sectional view of a conventional HC refrigerator. In FIG. 3, 1 is the body of the refrigerator, 2 is a heat-insulating box,
3 is an outer box, 4 is an inner box, and 5 is a heat insulating material.
A door 6 is installed in the heat insulating box 2. A machine room 7 is provided at a lower rear portion of the main body 1. An evaporator 8 is installed on the back side of the inner box 4.

A compressor 9 is installed in the machine room 7,
Condenser 10, capillary tube 11, evaporation section 8,
The suction pipe 12 is sequentially connected in an annular shape to form a refrigeration cycle. The capillary tube 11 and the suction pipe 12 are installed in close contact with each other by heat exchange, for example, by soldering. The HC refrigerant 13 is enclosed in this refrigeration cycle.

Further, the refrigerating machine oil may be a paraffinic or naphthenic mineral oil, or a synthetic oil such as alkylbenzene or alpha-olefin. Further, when the solution viscosity is too low, synthetic oils such as esters, glycols and carbonates containing oxygen in the molecular structure may be used. Needless to say, these can be mixed and used.

Inside the inner box 4, there is installed an inside temperature control means 14 for controlling the temperature of the inner box 4 by stopping the operation of the compressor 9. Reference numeral 15 is an inside light, and 16 is a door switch for blinking the inside light 15.

Next, the operation of the above configuration will be described with reference to FIG. When the compressor 9 is operated, the high-temperature and high-pressure HC refrigerant 13 discharged from the compressor 9 exchanges heat with the outside air in the condenser 10 to be condensed and liquefied, and then flows into the capillary tube 11. The HC refrigerant 13 is decompressed by the capillary tube 11, evaporated by the evaporator 8, and exchanges heat with the air in the inner box 4.

Here, the evaporated and vaporized HC refrigerant 13 directly passes through the suction pipe 12 and returns to the compressor 9. At this time, since the capillary tube 11 and the suction pipe 12 are arranged in a heat exchange manner, the gas refrigerant HC refrigerant 13 in the suction pipe 12 having a low vapor temperature and the liquefied temperature in the capillary tube 11 are separated from each other. The high liquid HC refrigerant 13 exchanges heat, and the liquid HC refrigerant 13 has its enthalpy decreased and increased in the supercooling direction, and the gaseous HC refrigerant 13 has its enthalpy in the superheated direction. As a result, the refrigerating effect is increased and the refrigerating capacity of the refrigerating cycle is improved. Then, since the evaporator 8 installed on the back side in the inner box 4 is cooled, the inner box 4 is also cooled.

When the temperature of the inside 4 reaches a predetermined temperature, the inside temperature control means 14 stops the compressor 9 and stops cooling. Then, the temperature of the inner box 4 rises and the second
When the temperature reaches the predetermined temperature,
The compressor 9 is operated again and cooling is started.

[0011]

However, in the above conventional configuration, when a flammable HC refrigerant is used as the cooling refrigerant, the refrigerant circuit, the evaporator and the suction pipe,
When the welded portion with the capillary tube is damaged, flammable HC refrigerant leaks to the outside of the refrigerator. There is a problem that there is a danger that a combustor such as a gas stove or an oil stove is provided outside the refrigerator, and these serve as ignition sources to ignite a flammable HC refrigerant and cause an explosive explosion. Further, the HC refrigerant has poor lubricity as compared with the conventional CFC refrigerant, and there is a high possibility of impairing the thermal stability and the oxidation stability of the refrigerating machine oil.

[0012]

In a refrigerating cycle in which a compressor, a condenser, a capillary tube, an evaporator, and a suction pipe are sequentially connected in an annular shape, a hydrocarbon refrigerant enclosed in the refrigerating cycle. It is composed of a mixture of a sulfur-containing organic substance such as methyl mercaptan.

Further, in a refrigeration cycle in which a compressor, a condenser, a capillary tube, an evaporator, and a suction pipe are sequentially connected in an annular shape, the hydrocarbon refrigerant enclosed in the refrigeration cycle contains trimethylamine or the like. It is composed of a mixture of nitrogen-containing organic substances.

[0014]

According to the present invention, with the above-mentioned structure, even if flammable HC refrigerant leaks to the outside of the refrigerator when the welded portion of the refrigerant circuit or the evaporator and the suction pipe or the capillary tube is damaged, methyl mercaptan, etc. Since it is mixed with a sulfur-containing organic substance or a nitrogen-containing organic substance such as trimethylamine, it can be easily detected that leakage has occurred, and ignition by a combustion device such as a gas stove or an oil stove located outside the refrigerator can be detected. It is possible to avoid a serious accident in which the HC refrigerant is ignited and explodes.

Further, when compared with the conventional CFC refrigerant, the HC
Although the refrigerant was poor in lubricity, the lubricity by sulfur can be improved by mixing a sulfur-containing organic substance such as methyl mercaptan. Furthermore, regarding the point of impairing the thermal stability and oxidative stability of refrigerating machine oil, by mixing nitrogen-containing organic materials such as trimethylamine, these nitrogen-containing organic materials react first and the thermal stability of refrigerating machine oil is increased. And oxidative stability can be improved.

[0016]

Embodiments of the present invention will be described below with reference to the drawings, but the detailed description of the same configurations as those of the conventional example will be omitted and the same reference numerals will be given.

FIG. 1 is a sectional view of a refrigerator according to a first embodiment of the present invention. Reference numeral 15 is an HC refrigerant mixed with a sulfur-containing organic substance such as methyl mercaptan, which is enclosed in the refrigeration cycle.

Next, the operation of the above configuration will be described with reference to FIG. When the compressor 9 is operated, the high-temperature and high-pressure HC refrigerant 17 discharged from the compressor 9 exchanges heat with the outside air in the condenser 10 to be condensed and liquefied, and then flows into the capillary tube 11. The HC refrigerant 17 is decompressed by the capillary tube 11, evaporated by the evaporator 8, and exchanges heat with the air in the inner box 4.

Here, the evaporated and vaporized HC refrigerant 17 passes through the suction pipe 12 as it is and returns to the compressor 9. At this time, since the capillary tube 11 and the suction pipe 12 are arranged in a heat exchange manner, the gas refrigerant HC refrigerant 17 in the suction pipe 12 having a low vaporization temperature and the liquefied temperature in the capillary tube 11 are The high liquid HC refrigerant 17 exchanges heat, and the liquid HC refrigerant 17 has its enthalpy decreased and increased in the supercooling direction, and the gas HC refrigerant 17 has its enthalpy in the superheated direction.

As a result, the refrigerating effect is increased and the refrigerating capacity of the refrigerating cycle is improved. Then, since the evaporator 8 installed on the back side in the inner box 4 is cooled, the inner box 4 is also cooled.

When the temperature of the inside 4 reaches a predetermined temperature, the inside temperature control means 14 stops the compressor 9 and stops cooling. Then, the temperature of the inner box 4 rises and the second
When the temperature reaches the predetermined temperature,
The compressor 9 is operated again and cooling is started.

The threshold value of methyl mercaptan (the concentration of a substance that can be sensed by humans) is 2.1 ppb, which is considerably small.
That is, since a sulfur-containing organic substance such as methyl mercaptan has an odor even in a small amount, even if only a small amount leaks from the refrigeration cycle, it is possible to easily detect that the HC refrigerant 17 has leaked, and the HC refrigerant ignites and explodes. It is possible to avoid a serious accident of doing.

Although the above-mentioned refrigerating machine oil is enclosed in the compressor 9, the HC refrigerant 17 mixed with a sulfur-containing organic substance such as methyl mercaptan is dissolved in this refrigerating machine oil and supplied to the lubrication surface. Thus, under severe conditions such as boundary lubrication, it acts as an extreme pressure agent and prevents wear.

Evaluation was carried out using a roller pin type abrasion friction tester at a speed of 2 m / s, a load of 75 N and a time of 60 minutes. When a refrigerating machine oil consisting of alkylbenzene is applied to a test piece in advance and a wear test is conducted in a gas atmosphere of isobutane, which is one of HC, the wear amount of the test piece is 5 mg. On the other hand, the amount of wear in a gas atmosphere in which 500 ppm of methyl mercaptan was mixed with isobutane was reduced to 4.3 mg.

FIG. 2 is a sectional view of a refrigerator according to the second embodiment of the present invention. Reference numeral 18 denotes an HC refrigerant mixed with a nitrogen-containing organic substance such as trimethylamine, which is enclosed in the refrigeration cycle.

Next, the operation of the above configuration will be described with reference to FIG. When the compressor 9 is operated, the high-temperature and high-pressure HC refrigerant 18 discharged from the compressor 9 exchanges heat with the outside air in the condenser 10 to be condensed and liquefied, and then flows into the capillary tube 11. The HC refrigerant 18 is decompressed by the capillary tube 11, evaporated by the evaporator 8, and exchanges heat with the air in the inner box 4.

Here, the evaporated and vaporized HC refrigerant 18 passes through the suction pipe 12 as it is and returns to the compressor 9. At this time, since the capillary tube 11 and the suction pipe 12 are arranged in a heat exchange manner, the gas refrigerant HC refrigerant 18 in the suction pipe 12 having a low vaporization temperature and the liquefied temperature in the capillary tube 11 are separated from each other. The high liquid HC refrigerant 18 exchanges heat, and the liquid HC refrigerant 18 has its enthalpy decreased and increased in the supercooling direction, and the gaseous HC refrigerant 18 has its enthalpy increased in the superheat direction.

As a result, the refrigerating effect is increased and the refrigerating capacity of the refrigerating cycle is improved. Then, since the evaporator 8 installed on the back side in the inner box 4 is cooled, the inner box 4 is also cooled.

When the temperature of the inside 4 reaches a predetermined temperature, the inside temperature control means 14 stops the compressor 9 and stops cooling. Then, the temperature of the inner box 4 rises and the second
When the temperature reaches the predetermined temperature,
The compressor 9 is operated again and cooling is started.

The threshold value of trimethylamine (the concentration of a substance that can be sensed by humans) is as small as 0.21 ppb.
That is, since the nitrogen-containing organic substance such as trimethylamine has an odor even in a small amount, even if only a small amount leaks from the refrigeration cycle, it is possible to easily detect that the HC refrigerant 18 has leaked, and the HC refrigerant ignites and explodes. It is possible to avoid such a serious accident.

The compressor 9 is filled with the above-mentioned refrigerating machine oil. When the HC refrigerant 18 mixed with a nitrogen-containing organic substance such as trimethylamine is dissolved in the refrigerating machine oil to reach a high temperature, the nitrogen-containing organic matter is discharged. By allowing the substance to react faster than the refrigerating machine oil, the thermal stability and oxidation stability of the refrigerating machine oil can be improved.

Equal amounts of refrigerating machine oil consisting of isobutane, which is one of the HC refrigerants, and naphthenic mineral oil were filled in a pressure vessel having an internal volume of 200 ml, and a heating test was carried out at 175 ° C. for one month.
A test under the same conditions was conducted using an HC refrigerant in which isobutane was mixed with 200 ppm of trimethylamine. The refrigerating machine oil after heating test with an HC refrigerant mixed with trimethylamine was slightly colored, but the total acid value, which is an index of oxidative deterioration and thermal stability, increased by only 0.02 mgKOH / g. However, the total acid number of the oil after the test with HC refrigerant not containing trimethylamine was 0.08 mgKOH.
/ G greatly changed.

[0033]

As described above, the refrigerating apparatus of the present invention is a refrigerating cycle in which a compressor, a condenser, a capillary tube, an evaporator and a suction pipe are sequentially connected in an annular shape. By mixing a sulfur-containing organic substance such as methyl mercaptan with the hydrocarbon refrigerant sealed in, the flammable HC refrigerant in the refrigerator is broken when the refrigerant circuit or the weld between the evaporator and the suction pipe or the capillary tube is damaged. Even if it leaks to the outside,
Since a sulfur-containing organic substance such as methyl mercaptan is mixed, it is possible to detect the leak easily, avoid ignition by a combustion device such as a gas stove or an oil stove outside the refrigerator, and the HC refrigerant will ignite. It is possible to avoid a serious accident of exploding.

In addition, when compared with the conventional CFC refrigerant, HC
Although the refrigerant was poor in lubricity, the lubricity by sulfur can be improved by mixing a sulfur-containing organic substance such as methyl mercaptan.

In a refrigeration cycle in which a compressor, a condenser, a capillary tube, an evaporator and a suction pipe are sequentially connected in an annular shape, the hydrocarbon refrigerant enclosed in the refrigeration cycle is filled with trimethylamine or the like. By mixing the nitrogen-containing organic substance, even if flammable HC refrigerant leaks to the outside of the refrigerator when the refrigerant circuit or the welded parts of the evaporator and the suction pipe or capillary tube are damaged, even if the flammable HC refrigerant leaks to the outside of the refrigerator, Since the nitrogen organic substance is mixed, it is possible to easily detect the leakage. As a result, it is possible to avoid ignition by a combustion device such as a gas stove or an oil stove outside the refrigerator, and avoid a serious accident in which the HC refrigerant ignites and explodes.

Further, regarding the point of impairing the thermal stability and the oxidation stability with respect to the refrigerating machine oil, the refrigerating machine oil is mixed by mixing the nitrogen-containing organic material such as trimethylamine and the like, and the nitrogen-containing organic material reacts first. The thermal stability and oxidative stability of can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a refrigerating apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a refrigerating apparatus according to a second embodiment of the present invention.

FIG. 3 is a sectional view of a conventional refrigerator.

[Explanation of symbols]

 8 Evaporator 9 Compressor 10 Condenser 11 Capillary tube 12 Suction pipe 17 Sulfur-containing organic HC refrigerant 18 Nitrogen-containing organic HC refrigerant

Claims (2)

[Claims] 1. In a refrigeration cycle in which a compressor, a condenser, a capillary tube, an evaporator, and a suction pipe are sequentially connected in an annular shape, methyl mercaptan or the like is added to the hydrocarbon refrigerant enclosed in the refrigeration cycle. A refrigerating apparatus comprising the sulfur-containing organic substance of 1. 2. In a refrigeration cycle in which a compressor, a condenser, a capillary tube, an evaporator, and a suction pipe are sequentially connected in an annular shape, a hydrocarbon refrigerant enclosed in the refrigeration cycle is filled with trimethylamine or the like. A refrigerating apparatus comprising a mixture of nitrogen-containing organic substances. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerant, and more particularly to a refrigeration system using a flammable refrigerant.