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 combi ned with the UNIFAC group contribution method to yield a completely pr edictive thermodynamic model for the vapor-liquid and liquid-liquid ph ase behavior of slightly and highly non-ideal mixtures over large rang es of temperature and pressure. We find that the quality of prediction s is very good for systems for which UNIFAC provides an accurate low p ressure description. The mixing rule + UNIFAC model developed is an ac curate and very simple extension of the UNIFAC group contribution meth od to high temperatures and high pressures. Further, since existing UN IFAC parameters are used, no refitting of experimental data is needed.