Refrigerant compositions

Details Refrigerant compositions Refrigerant compositions

1999-05-07

2000-09-12

Skane, Christine

Compositions

Vaporization, or expansion, refrigeration or heat or energy...

62114, C09K 504

Patent

active

061173568

DESCRIPTION:

BRIEF SUMMARY
This invention relates to compositions which are suitable for refrigeration applications and to the use of such compositions in heat transfer devices such as refrigeration and air conditioning systems. The invention relates, in particular, to refrigerant compositions which can be used in the applications currently satisfied by dichlorodifluoromethane (refrigerant R-12).
Heat transfer devices of the mechanical compression type such as refrigerators, freezers, heat pumps and air conditioning systems are well known. In such devices a refrigerant liquid of a suitable boiling point evaporates at low pressure taking heat from a neighbouring heat transfer fluid. The resulting vapour is then compressed and passes to a condenser where it condenses and gives off heat to another heat transfer fluid. The condensate is then returned through an expansion valve to the evaporator so completing the cycle. The mechanical energy required for compressing the vapour and pumping the liquid may be provided by an electric motor or an internal combustion engine.
In addition to having a suitable boiling point and a high latent heat of vaporisation, the properties preferred of a refrigerant include low toxicity, non-flammability, non-corrosivity, high stability and freedom from objectionable odour.
Hitherto, heat transfer devices have tended to use fully and partially halogenated chlorofluorocarbon refrigerants such as bromotrifluoromethane (refrigerant R-13B1), trichlorofluoromethane (refrigerant R-11), dichlorodifluoromethane (refrigerant R-12), chlorodifluoromethane (refrigerant R-22) and the azeotropic mixture of chlorodifluoromethane and chloropentafluoroethane (refrigerant R-115); the azeotrope being refrigerant R-502. Refrigerant R-12, for example, has been widely used in automobile air conditioning and domestic refrigeration systems.
However, the fully halogenated chlorofluorocarbons in particular have been implicated in the destruction of the earth's protective ozone layer and as a result the use and production thereof has been limited by international agreement.
Whilst heat transfer devices of the type to which the present invention relates are essentially closed systems, loss of refrigerant in the atmosphere can occur due to leakage during operation of the equipment or during maintenance procedures. It is important, therefore, to replace fully halogenated chlorofluorocarbon refrigerants by materials having low or zero ozone depletion potentials.
In addition to the possibility of ozone depletion, it has been suggested that significant concentrations of chlorofluorocarbon refrigerants in the atmosphere might contribute to global warming (the so-called greenhouse effect). It is desirable, therefore, to use refrigerants which have relatively short atmospheric lifetimes as a result of their ability to react with other atmospheric constituents such as hydroxyl radicals.
Replacements for some of the chlorofluorocarbon refrigerants presently in use have already been developed. These replacement refrigerants tend to comprise selected hydrofluoroalkanes, i.e. compounds which contain only carbon, hydrogen and fluorine atoms in their structure. Thus, refrigerant R-12 is generally being replaced by 1,1,1,2-tetrafluoroethane (R-134a).
Although suitable replacement refrigerants are available, there is still a need for new refrigerants having a low or zero ozone depletion potential that are capable of replacing the chlorofluorocarbon refrigerants presently in use such as R-12. Furthermore, very real benefits could be realised by a new replacement refrigerant having a higher refrigeration capacity than the chlorofluorocarbon refrigerant it is replacing.
The present invention provides a composition comprising a mixture of compounds having zero ozone depletion potentials which can be used as a replacement for refrigerant R-12 in the automobile air conditioning and domestic refrigeration systems. The composition of the invention can exhibit an advantageously high refrigeration capacity.
According to the present invention there is provided a

REFERENCES:
patent: 5736063 (1998-04-01), Richard et al.
Chemical Abstracts, AN 129:124258, "Ternary mixture as R22 replacement in heat pumps", Maczek et al., no month available 1997.

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