A perturbed-hard-sphere-chain equation of state for phase equilibria of mixtures containing a refrigerant and a lubricant oil

A modification of the perturbed-hard-sphere-chain equation of state (EOS) i s used to describe vapor-liquid (VLE) and liquid-liquid equilibria (LLE) of mixtures containing new-generation refrigerants and a lubricant oil. For r efrigerants, pure-component parameters are obtained from thermodynamic data . For the oil, they are predicted by a group-contribution method, and the c alculation is checked on liquid density values of polyol-ester lubricants. Extension to mixtures is performed by using conventional one-fluid mixing r ules with binary interaction parameters regressed from VLE experimental dat a, VLE calculations are reported for mixtures containing a refrigerant and a polyol-ester lubricant over wide temperature and concentration ranges. Th e thermodynamic condition for LLE is checked. If two liquid phases are pres ent, LLE is calculated and compared with experimental measurements. (C) 199 9 Elsevier Science B.V. All rights reserved.