Phase equilibria of CFC alternative refrigerant mixtures. Binary systems of trifluoromethane (HFC-23)+1,1,1,2-tetrafluoroethane (HFC-134a) and trifluoromethane (HFC-23)+1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) at 283.15 and 293.15 K

Isothermal vapor-liquid equilibria for the binary mixtures of trifluorometh ane (HFC-23) + 1,1,1,2-tetrafluoroethane (HFC-134a) and trifluoromethane 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea) were measured at 283.15 and 29 3.15 K. The experiments were carried out with a circulation-type equilibriu m apparatus with measurement of the temperature, pressure, and compositions of the liquid and vapor phases. The experimental data were correlated with the Peng-Robinson equation of state using the Wong-Sandler mixing rules. R esults calculated with this equation showed good agreement with the experim ental data. Azeotropic behavior has not been found in either of these mixtu res.