An interpretation of the behavior of EoS/G(E) models for asymmetric systems

The recently developed EoS/G(E) models are mixing rules for the equations o f state energy parameters based on the equality of the G(E,)s as Obtained f rom the EoS and from an explicit G(E)/activity coefficient model, e.g. UNIF AC, NRTL. This equality is, depending on the model, postulated at infinite or zero pressure or at other conditions (system's pressure, constant volume packing fraction). In a number of publications over the last years, the ac hievements and the shortcomings of the various EoS/G(E) models have been pr esented via phase equilibrium calculations. This short communication provid es an explanation of several literature EoSIGE models, especially those bas ed on zero-reference pressure (PSRK, MHV1, MHV2), in the prediction of phas e equilibria for asymmetric systems as well as an interpretation of the LCV M and kappa-MHV1 models which provide an empirical - yet as shown here theo retically justified - solution to these problems. (C) 2000 Elsevier Science Ltd. All rights reserved.