Excess enthalpies of 14 binary liquid mixtures of .alpha.,.omega.-dihalo (Cl, Br, I)alkanes (C2-C6) + cyclohexane. Experimental data and group contribution (DISQUAC) analysis of an extended database

Abstract

Experimental pressure-temperature (P-T) data at several constant densíties were obtained for gaseous non­ chlorinated refrigerant fluíds, difluoromethane (R 32), pentaftuoroethane (R 125), 1,1,1,2-tetrafluoroethane (R 134a), and 1,1,1,2,3,3,3-heptafluoropropane (R 227ea), by using of a new constant-volume cell constructed to work at high pressures at temperatures from 273.15 Kto 353.15 K. The vapor pressures were estimated graphically at tM break point of the measured P-T curves. The vapor pressure values were co"elated using Antoine and Wagner equatíons. These data, and the derived acentric factors and enthalpies of vaporization, agree within 2 to 5 % with /iterature values.