Isothermal Vapor–Liquid Equilibrium Data for Binary Mixtures of Hexafluoroethane (R116) + n-Pentane or n-Hexane at Two Temperatures, 288 and 296 K

The isothermal vapor–liquid equilibrium (VLE) data for two hexafluoroethane (R-116)/ n -alkane systems were each measured at two temperatures of 288 and 296 K. The two n -alkanes of interest are n -pentane and n -hexane. The pressures which were measured ranged from 0.017 to 7.040 MPa. A “static-analytic” VLE apparatus, equipped with pneumatic Rapid Online Sampler-Injector (ROLSI) capillary samplers, was used to perform the measurements. The ROLSI gives this apparatus the capability of sampling both the liquid and the vapor phases, without significant equilibrium perturbation with respect to the estimated analytical uncertainties. Vapor–liquid–liquid equilibria and liquid–liquid equilibria were experienced at R-116 compositions close to unity for the R-116 and n -hexane system. Each of the four P – x – y VLE data sets was correlated with the Peng–Robinson equation of state, modified by the inclusion of the Mathias-Copeman alpha function in preference to the original Peng-Robinson configuration. The Wong-Sandler mixing rule, combined with the non-random two-liquid (NRTL) activity coefficient model, was used to account for the properties of the mixture.