A modified Patel–Teja cubic equation of state. Part II: Parameters for polar substances and its mixtures

Abstract

In this work, the parameters of the equation of state formed by the Patel–Teja pressure–volume–temperature relationship and the alpha function of Heyen have been estimated for 184 polar substances. To obtain the parameters of the proposed model, pseudo-experimental data have been generated using the DIPPR correlations for vapor pressure and liquid density. The proposed model in conjunction with the Wong–Sandler mixing rules and the NRTL activity model have been used to describe the vapor liquid equilibria of some complex mixtures. Three kinds of binary systems have been analyzed and they are those of the type: polar substance/aromatic, polar substance/n-alkane and polar substance/n-alkanol. Based on the homologous series concept, generalized expressions for the binary interaction parameters in the Wong–Sandler-NRTL mixing rules were developed in order to correlate vapor–liquid equilibrium at low pressures for the selected mixtures. For n-alkanes and aromatic compounds, the acentric factor has been used to generalize the binary interaction parameters for mixtures with a polar substance and these kinds of compounds. In the case of systems composed by a polar substance and an alcohol, the reduced dipole moment of the alcohols is used to develop the generalized expressions. Ninety-two binary mixtures were analyzed and a relative average absolute deviation of 1.21% was estimated for the bubble pressure. Finally, the model was validated by predicting binary vapor–liquid equilibrium at high pressures and for ternary mixtures. In both cases, the results are satisfactory. The average absolute deviations in bubble pressure are 2.34% for high pressure predictions and 1.15% for ternary mixtures.