ACCURATE EQUATION OF STATE PREDICTIONS AT HIGH-TEMPERATURES AND PRESSURES USING THE EXISTING UNIFAC MODEL

A recently developed mixing rule for cubic equations of state is combined with the UNIFAC group contribution method to yield a completely predictive thermodynamic model for the vapor-liquid and liquid-liquid phase behavior of slightly and highly non-ideal mixtures over large ranges of temperature and pressure. We find that the quality of predictions is very good for systems for which UNIFAC provides an accurate low pressure description. The mixing rule + UNIFAC model developed is an accurate and very simple extension of the UNIFAC group contribution method to high temperatures and high pressures. Further, since existing UNIFAC parameters are used, no refitting of experimental data is needed.