MEASUREMENTS OF THE VAPOR LIQUID COEXISTENCE CURVE IN THE CRITICAL REGION FOR REFRIGERANT MIXTURE R152A/R22

Considering the alternatives of CFCs, measurements of the vapor-liquid coexistence curve in the critical region for the binary refrigerant mixture of 1,1-difluoroethane (R152a, CH3CHF2) / chlorodifluoromethane (R22, CHClF2) system with three compositions of 20, 50 and 80wt% R152a have been carried out by visual observation of meniscus disappearance of the sample at the vapor-liquid interface within an optical cell. Thirty-one saturated vapor and liquid data points in the critical region were measured in the temperature range from 372 to 385 K. Based on these measurements, the critical temperatures and densities at three different compositions for the R152a / R22 system were determined. Critical locus of temperature-density have been discussed analytically and correlations of T(c) and V(c) with the compositions for R152a / R22 system are proposed.