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Study to Determine the Existence of An Azeotropic R-22 "Drop-In" Substitute.

pdf icon Study to Determine the Existence of An Azeotropic R-22 "Drop-In" Substitute. (1601 K)
Kim, M. S.; Morrison, G.; Mulroy, W. J.; Didion, D. A.

NISTIR 5784; 48 p. March 1996.


Electric Power Research Institute, Palo Alto, CA

Available from:

National Technical Information Service
Order number: PB96-167812


azeotropic refrigerant mixtures; air conditioning; heat pumps; alternative refrigerants; refrigeration; working fluids; HFC-134a; propane; cyclopropane; isobutane


The reduction in chlorofluorocarbon (CFC) and hydrochlorofluorocarbon (HCFC) production and the scheduled phase-out of these ozone depleting refrigerants requires the development and determination of environmentally safe refrigerants for use in heat pumps, water chillers, air conditioners and refrigerators. Azeotropic mixtures are attractive as alternative refrigerants because they behave very nearly as pure materials. A simple correlation scheme that allows one to judge whether or not an azeotrope is likely in a binary refrigerant mixture is discussed. This paper presents laboratory and computer simulation evaluation of two of the azeotropic refrigerant mixtures which were identified, HFC-134a (1,1,1,2-tetrafluoroethane) with R-290 (Propane) and HFC-134a with R-600a (isobutane), in a generic heat pump apparatus. A third azeotropic mixture, HFC-134a with R-C290 (Cyclopropane) is examined by computer simulation only. The performance characteristics of these azeotropes were compared with pure CFC-12, HFC-134a, HCFC-22, and R-290 at high temperature cooling and heating conditions. Use of liquid-line/suction-line heat exchange was evaluated.