Compositions – Vaporization – or expansion – refrigeration or heat or energy...
Patent
1997-07-09
2000-04-25
Skane, Christine
Compositions
Vaporization, or expansion, refrigeration or heat or energy...
62114, C09K 504
Patent
active
060540648
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to refrigerants, to refrigerant compositions containing these refrigerants, and to the use of these refrigerants in heat transfer equipment, in particular in mechanical refrigeration systems.
TECHNOLOGY REVIEW
The invention relates in particular to refrigerants referred to as the "medium and low temperature" type, that is to say refrigerants making it possible to achieve temperatures of between about -25.degree. C. and -50.degree. C., which can be used in all fields of medium and low temperature refrigeration such as, in particular, commercial refrigeration, refrigerated transport, air conditioning and various industrial processes, as well as refrigerants referred to as the "very-low temperature" type, that is to say refrigerants making it possible to achieve temperatures of between about -50.degree. C. and -100.degree. C.
In mechanical refrigeration systems, the evaporation of a liquid refrigerant at low pressure causes heat to be removed from the medium surrounding the evaporator. The gas resulting from the evaporation is then compressed and sent to a condenser where it condenses, giving up the heat to the medium surrounding the condenser. Finally, the condensate is returned to the evaporator through a pressure-relief valve. Systems of this type are described in Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed., 1988, vol. B3, chapter 19, pages 1 to 20.
Chlorodifluoromethane (R-22) or the azeotrope of R-22 with chloropentafluoroethane (R-115), referred to as R-502, are conventionally used in mechanical refrigeration systems of the "medium and low temperature" type. Chlorotrifluoromethane (R-13), bromotrifluoromethane (R-13B1) or the azeotrope of R-13 with trifluoromethane (R-23), referred to as R-503, are conventionally used in "very-low temperature" mechanical refrigeration systems. Chlorofluorocarbons, such as R-13 and R-115, bromofluorocarbons, such as R-13B1, and hydrochlorofluorocarbons, such as R-22, have for a number of years been suspected of having detrimental effects on the stratospheric ozone layer. Various international agreements stipulate the progressive reduction, or even complete cessation, of their manufacture and their use. Further to the possibility of destroying ozone, it has been suggested that significant concentrations of halogenated refrigerants in the atmosphere could contribute to the atmospheric warming phenomenon (this phenomenon is referred to as the greenhouse effect). It is therefore desirable to replace existing refrigerants by substitute refrigerants, which do not contain chlorine, thereby having zero ozone depletion potential (ODP), and which preferably have a relatively short lifetime in the atmosphere, thereby having a low global warming potential (HGWP).
Further to having minimal environmental impact, a substitute refrigerant should preferably be non-toxic, non-inflammable, chemically stable and non-corrosive. Furthermore, it should have suitable physical and thermodynamic properties, ideally making it possible to obtain similar efficiency, refrigeration capacity, compressor discharge temperature and compression ratio to those of the refrigerant which it replaces, as well as, if possible, a higher pressure in the evaporator than atmospheric pressure, in order to prevent any moisture from entering the refrigeration system.
Certain refrigerants which do not destroy the stratospheric ozone layer have already been proposed as a replacement for R-22 or R-502. In particular, U.S. Pat. No. 5,035,823 has proposed a refrigerant consisting of 1,1,1-trifluoroethane (R-143a) and 1,1,1,2-tetrafluoroethane (R-134a); patent application WO 92/19199 has proposed a refrigerant consisting of difluoromethane (R-32) and R-134a; patent application WO 92/16597 has proposed a refrigerant consisting of trifluoromethane (R-23), R-32 and R-134; and U.S. Pat. No. 5,211,867 has proposed a refrigerant consisting of 1,1,1-trifluoroethane (R-143a) and pentafluoroethane (R-125). However, these refrigerants have some drawbacks, including a
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Balthasart Dominique
Barthelemy Pierre
Buchwald Hans
D'Aubarede Bruno
Doering Reinhold
Schneller John W.
Schneller Marina V.
Skane Christine
Solvay ( Societe Anonyme)
Solvay Fluor und Derivate GmbH
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