NIST Time|NIST Home|About NIST|Contact NIST

HomeAll Years:AuthorKeywordTitle2005-2010:AuthorKeywordTitle

Simulation of Isothermal and Adiabatic Leak Processes of Zeotropic Refrigerant Mixtures.


pdf icon Simulation of Isothermal and Adiabatic Leak Processes of Zeotropic Refrigerant Mixtures. (1322 K)
Kim, M. S.; Didion, D. A.

HVAC&R Research, Vol. 1, No. 1, 3-20, January 1995.

Keywords:

refrigerants; predictive models; isothermal leak process; adiabatic leak process; heat pumps; air conditioners; simulation

Abstract:

Nonflammable zeotropic mixtures of flammable and nonflammable rerigerants are possible alternative refrigerants for use in domestic heat pumps and air conditioners. Refrigerant leakage from such a system is of paramount concern since it is possible that a mixture composition will shift to a flammable range. This paper presents simulations of leak processes of zeotropic refrigerant mixtures. Idealized cases of isothermal and adiabatic leak processes are considered in this study as representations of slow and fast leaks, respectively. Results of simulations are presented for a selected composition of binary and ternary refrigerant mixtures: R-32/134a and R-32/125/134a. Mass fraction changes of the mixtures are presented with respect to the percentage leak of the original charge. In the isothermal leak process, the fraction of the more volatile refrigerant in both vapor and liquid phases decreases for either a vapor or a liquid leak. The mass fraction changes at a low initial temperature are greater than those at a high initial temperature. During the adiabatic leak process, the vapor mass fraction of the more volatile component increases, while the liquid mass fraction of that component decreases for both vapor and liquid leak processes.