Extended statistical associating fluid theory (SAFT) equations of state for dipolar fluids

Abstract Polar forces have a considerable effect on the thermodynamic and phase equilibrium properties of pure and mixture fluids. In this work, the statistical associating fluid theory (SAFT) and perturbed chain–SAFT (PC‐SAFT) are extended to explicitly account for dipole–dipole interactions. A recently proposed perturbation theory for pure dipolar fluids is incorporated in both models and further extended to mixtures. Polar SAFT (PSAFT) and PC‐polar SAFT (PC‐PSAFT) are applied to alcohols, ketones, water, and other dipolar fluids. Vapor pressure and saturated liquid densities are correlated over a wide temperature range from low temperature up to very near the critical point. Critical constants, second virial coefficients, and monomer fraction predictions are reported. Furthermore, the models are applied to correlate the vapor–liquid equilibria of binary mixtures. A temperature‐independent binary interaction parameter is regressed from experimental data. Finally, model predictions for representative polar ternary mixtures are presented. In all cases, very good agreement with experimental data is obtained. © 2005 American Institute of Chemical Engineers AIChE J, 2005