Thermodynamic Properties of HFC-32/HFC-134a Binary System

In this paper, we discussed the development of equation of state for a binary mixture refrigerant from the equations of state for both constituent refrigerants.We have developed IS-coefficient modified Benedict-Webb -Rubin equations of state for HFC-134a (1,1,1,2-tetraflu oroethane), HCFC-123 (1,1dichloro-2,2,2-t rifluoroethane), and HFC-32 (difluoromethan e), respectively.The van der Waals mixing rule has been applied on the 2nd virial coefficients of the equations of state for HFC-32 and HFC-134a, and a linear mixing rule on the other coefficients.The equation of state for the refrigerant mixture represents all of the available PVTx measurements ofHFC-32/HFC -134a at 20, 40, 60, and 80 wt% within ±0.5 % in pressure.For two phase region, the Peng-Robinson equation of state and the Hankinson-Bro bst-Thomson equation optimized by Widiatmo et al.(l) are adopted in this study.The thermodynamic properties of HFC-32/HFC-1 34a in superheated vapor phase and two phase region at any composition could be calculated from the developed equations.The thern10dynamic property tables and pressure-enthalp y diagram for HFC-32/HFC-1 34a binary system with 30/70 wt% are also included in the present paper. INTRODUCT IONHCFC-22 (chloroditluorom ethane) is one of the most important working fluids in the air-conditioning systems.But it is scheduled to be phased out before 2030 due to the possibility of ozone depletion and global wanning effect, and the time limit for the phaseout seems to be forwarded.There is no singlecomponent refrigerant to replace HCFC-22 at the moment, and some of the binary and/or ternary mixtures were proposed.HFC-32/HFC-l 34a binary system is considered as one of the most probable substances to replace HCFC-22.Both ofHFC-32 and HFC-134a do not have chlorine atoms, so that the