Molecular thermodynamic models for the vapor-liquid equilibrium of nonpolar fluids

We propose simple expressions giving the main vapor-liquid properties for 4 2 nonpolar fluids. These expressions are molecular models based on a pertur bative procedure, where the Lennard-Jones (LJ) system is taken as reference , the perturbed expressions being simple polynomial functions of the temper ature for a given substance. The molecular parameters used, which are the only input needed in the molec ular models, are the two LJ parameters, related to molecular size and the m olecular interaction intensity, and the acentric factor, related to the mol ecular shape, The proposed molecular models are extrapolatable outside the temperature ra nge used in the fit and seem to be easily applicable to other nonpolar flui ds.