THE SIMPLEST CUBIC EQUATION OF STATE FOR LOW-PRESSURE VAPOR-LIQUID-EQUILIBRIUM CALCULATIONS

A simple, virial-like cubic equation of state has been developed from the general form of the perturbed hard core model. The equation simultaneously incorporates saturation liquid volume and saturation pressure information for pure compounds. With two adjustable parameters per binary, it can represent low-pressure vapor-liquid equilibria as well or better than dual methods. This model applies a single equation to both phases and necessitates only a fraction of the input information required by dual methods. The results indicate that the cubic equations do not necessarily need a van der Waals type hardcore term in order to successfully predict the phase equilibrium. © 1990.