Vapor-liquid equilibria of alternative refrigerants by molecular dynamics simulations

Alternative refrigerants HFC-152a (CHF2CH3), HFC-143a (CF3CH3), HFC-134a (C F3CH2F), and HCFC-142b (CF2ClCH3) are modeled as a dipolar two-center Lenna rd-Jones fluid. Potential parameters of the model are fitted to the critica l temperature and vapor-liquid equilibrium data. The required vapor liquid equilibrium data of the model fluid are computed by the Gibbs-Duhem integra tion for molecular elongations L = 0.505 and 0.67, and dipole moments mu*(2 ) = 0, 2, 4, 5, 6, 7, and 8. Critical properties of the model fluid are est imated from the law of rectilinear diameter and critical scaling relation. The vapor liquid equilibrium data are represented by Wagner equations. Comp arison of the vapor liquid equilibrium data based on the dipolar two-center Lennard-Jones fluid viith data from the REFPROP database shows good-to-exc ellent agreement for coexisting densities and vapor pressure.