Vapor-liquid equilibria in nonpolar/weakly polar systems with different types of mixing rules

Abstract

A comprehensive comparison of six mixing rules: the one- and two-parameter conventional ones (1PCMR and 2PCMR); the pressure- and density-dependent ones (PDMR and DDMR); and two based on G E models (MHV2MR and the Sandler-Wong, SWMR), used with cubic equations of state, is presented using an extensive database of nonpolar/weakly polar binary systems. Parameter values are determined by fitting the P-T-x data and are then used in the prediction of vapor phase mole fractions (y), and saturated liquid (ϱ L) and vapor (ϱ V) densities. Best result are obtained with the 2PCMR, PDMR, MHV2MR and SWMR with typical errors of 2% in P, 3% in ϱ L and 7% in ϱ V ; and deviations in y of 0.012, except for the SWMR which gives poorer predictions for systems where one component is highly supercritical. Surprisingly, the DDMR does not perform as well as it might be expected. All models, however, finally give poorer results in the near-critical region.