Phase equilibria of chlorofluorocarbon alternative refrigerant mixtures. Binary systems of trifluoromethane plus isobutane at 283.15 and 293.15 K and1,1,1-trifluoroethane plus isobutane at 323.15 and 333.15 K

Isothermal vapor-liquid equilibrium data of the binary mixtures of trifluor omethane (HFC-23) + isobutane (R600a) and 1,1,1-trifluoroethane (HEC-143a) + isobutane have been measured at 283.15 and 293.15 K and at 323.15 and 333 .15 K, respectively. The experiment was carried out with a circulation-type equilibrium apparatus with the measurement of temperature, pressure, and t he compositions of the liquid and vapor phases. The experimental data were correlated with the Peng-Robinson equation of state using the Wong and Sand ler mixing rules.