Phase Equilibria for Perfluoroethane + (n‑Perfluorohexane or n‑Perfluorooctane) Binary Systems: Measurement and Modeling

Isothermal vapor–liquid equilibrium (VLE) data are presented for binary systems of perfluoroethane with either n-perfluorohexane or n-perfluorooctane. The measurements were performed at five temperatures ranging from (272.80 to 312.92) K for the perfluoroethane + n-perfluorohexane binary system and at four temperatures ranging from (282.89 to 312.95) K for the perfluoroethane + n-perfluorooctane binary system. Vapor pressure data were measured for perfluoroethane, n-perfluorohexane, and n-perfluorooctane. The data was measured using a “static-analytic” type apparatus. The expanded uncertainties in temperature, pressure, and both the liquid and vapor compositions (mole fractions) were estimated as 0.09 K, 0.01 MPa, and 0.015 and 0.006, respectively. The VLE data were correlated with the Peng–Robinson equation of state utilizing the classical one-fluid mixing rule. The experimental data were accurately represented by the model. The relative deviations in pressure and composition were within 1%. The critical region of the phase envelope was well represented by the model.