Refrigeration – Processes – Employing diverse materials or particular material in...
Reexamination Certificate
2000-02-14
2001-04-17
McDermott, Corrine (Department: 3744)
Refrigeration
Processes
Employing diverse materials or particular material in...
Reexamination Certificate
active
06216476
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an apparatus having a refrigeration cycle, which uses a flammable refrigerant comprising, as a main component, one of propane (R290), isobutane (R600a) and ethane (R170), or a mixture of a plurality of these components.
BACKGROUND TECHNIQUE
At present, Freon-based refrigerants that have stable properties and are easy to be handled are used as refrigerants of an apparatus having a refrigeration cycle such as a refrigerator and an air conditioner.
However, although the Freon refrigerants have stable properties and are easy to be handled, it is said that the Freon refrigerants destroy the ozone layer, and since the Freon refrigerants adversely affect the global environment, the use of the Freon refrigerants will be entirely prohibited in the future after a preparatory period of time. Among the Freon refrigerants, hydro fluorocarbon (HFC) refrigerants do not seem to destroy the ozone layer, but they have properties to facilitate the global warming. Especially in Europe where the people are concerned about environmental problems, there is a tendency to prohibit the use of this refrigerant also. That is, there is a tendency that the use of the Freon refrigerants that are artificially produced is prohibited, and natural refrigerants such as hydrocarbon are used as in the past. However, such natural refrigerants are flammable, and limited resources must be used effectively, there is a problem that the amount of usage must be controlled.
Therefore, when refrigerant such as propane or isobutane is used in the apparatus having the refrigeration cycle, in order to reduce the amount of refrigerant to be used, it is effective to use refrigerating machine oil having less mutual solubility with the refrigerant.
However, in order to reduce the mutual solubility between the refrigerant and the refrigerating machine oil, since the polarity of the refrigerant is almost nonpolar, it is effective to use refrigerating machine oil having great polarity, but there is a problem that refrigerating machine oil having great polarity is liable to absorb water, and refrigerating machine oil which absorbs water is decomposed by strong sliding movement.
Thereupon, it is an object of the present invention to prevent the decomposition of refrigerating machine oil due to absorption of water, and to reduce the amount of refrigerant used in an apparatus having a refrigeration cycle by using refrigerating machine oil having less mutual solubility with the refrigerant.
Another object of the invention is to further reduce the amount of refrigerant used in the apparatus having the refrigeration cycle by using refrigerating machine oil suitable for reducing the refrigerant.
Another object of the invention is to provide an apparatus having a refrigeration cycle capable of obtaining the long term reliability by using refrigerating machine oil which generates few sediment and which is excellent in sealing performance and lubricating performance of sliding surface.
DISCLOSURE OF THE INVENTION
In a refrigeration cycle formed by annularly connecting a compressor, a condenser, an expansion device and an evaporator with one another, the present invention relates to an apparatus having such a refrigeration cycle, which uses a refrigerant comprising, as a main component, one of propane, isobutane and ethane, or a mixture of a plurality of these components, and uses refrigerating machine oil for the compressor having less mutual solubility with the refrigerant.
Therefore, according to the present invention, it is possible to reduce the solution amount of refrigerant into the refrigerating machine oil by selecting such refrigerant and refrigerating machine oil, and to reduce the amount of refrigerant to be charged into the apparatus having the refrigeration cycle.
To achieve the above object, according to a first aspect of the present invention, there is provided an apparatus having a refrigeration cycle, where the refrigeration cycle is formed by annularly connecting a compressor, a condenser, an expansion device and an evaporator with one another, the apparatus uses a refrigerant comprising, as a main component, one of propane, isobutane and ethane, or a mixture of a plurality of these components, and uses refrigerating machine oil having less mutual solubility with the refrigerant, and a dryer is provided in the refrigeration cycle for absorbing water.
Since propane, isobutane and the like are refrigerants whose polarities are almost nonpolar, refrigerating machine oil having great polarity is preferable as refrigerating machine oil having less mutual solubility, but refrigerating machine oil having great polarity is liable to absorb water in the atmosphere, and if refrigerating machine oil which absorbs water is used as it is, the refrigerating machine oil is decomposed by strong sliding movement of the mechanical portion of the compressor, and loss of the sliding movement is increased and sufficient reliability can not be obtained. Therefore, in order to maintain the concentration of water in the refrigeration cycle at a low level, the dryer is disposed in the refrigeration cycle to absorb, fix and hold the water. With this feature, it is possible to obtain the sufficient reliability even in an apparatus having a refrigeration cycle using refrigerating machine oil having great polarity.
According to a second aspect of the invention, there is provided an apparatus having a refrigeration cycle, where the refrigeration cycle is formed by annularly connecting a compressor, a condenser, an expansion device and an evaporator with one another, the apparatus uses a refrigerant comprising, as main component, one of propane, isobutane and ethane, or a mixture of a plurality of these components, and uses refrigerating machine oil having less mutual solubility with the refrigerant, and an additive which reacts with water is included in the refrigerating machine oil.
By using an additive which reacts with water in the refrigerating machine oil, it is possible to easily maintain the concentration of water in the refrigeration cycle at low level without disposing an element such as the dryer.
According to a third aspect, in the first or second aspect, the refrigerating machine oil is carbonate compound. A base oil of such a refrigerating machine oil is liquid material having linear or annular carbon ester bond in molecular. The carbon ester bond has great polarizability, and the polarity of the compound having this carbon ester bond in its molecular is big, it is possible to suppress the mutual solubility with propane, isobutane or ethane of nonpolarity to a small level, and it is possible to reduce the refrigerant in the apparatus having the refrigeration cycle.
According to a fourth aspect, in the third aspect, the number of carbon forming carbonic acid ester bond occupies at least 10 atomic % of all the number of carbon forming the carbonate compound. By using the carbonate compound having such a structure, greater polarity can be obtained, it is possible to further suppress the mutual solubility with propane, isobutane or ethane of nonpolarity to a small level, and it is possible to further reduce the refrigerant in the refrigeration cycle of the apparatus. Further, if a bond portion including hetero atom such as ether bond, ester bond, amide bond or urea bond is included in a portion of the carbonate compound other than the carbon ester bond portion, the polarity is further increased, and the mutual solubility can be further reduced.
According to a fifth aspect, in the third aspect, the purity of the carbonate compound of the refrigerating machine oil is 99% or higher. With this feature, it is possible to suppress the sediment in the expansion device generated from the refrigerant by controlling the total amount of function group which has not yet reacted, and the sufficient long term reliability can be obtained.
According to a sixth aspect, in the first or second aspect, mutual solubility between the refrigerating machine oil and the refrigerant is 5 wt % or less at 25° C. It is prefer
Fujitaka Akira
Haneda Kanji
Kobayashi Yoshinori
Numoto Hironao
Sato Shigehiro
Armstrong Westerman Hattori McLeland & Naughton LLP
Drake Malik N.
Matsushita Electric - Industrial Co., Ltd.
McDermott Corrine
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