Prediction of vapor pressures and saturated molar volumes with a simple cubic equation of state: Part II: The Van der Waals - 711 EOS

Abstract

A simple cubic equation of state (EOS), the VdW-711 translation of the Van der Waals EOS is presented. It is applicable to nonpolar and slightly polar compounds. It was developed by using the reliable data base of vapor pressure, critical property, acentric factor, and saturated liquid volume values of Part I. Excellent results for vapor pressures, from 0.1 kPa to the critical, and for saturated molar volumes are obtained with errors below 5% and typically about 2 to 3%. Below 0.1 kPa, it is demonstrated that all of the cubic EOS investigated are unreliable for vapor pressure predictions. The equation has been successfully applied to compounds with acentric factors of up to 0.907, including several fossil fuel model compounds. It is shown that in the case of uncertainies in the critical properties and acentric factor values of hydrocarbons, good vapor pressure predictions are obtained with the VdW-711 EOS using estimates of these properties from the Lin and Chao correlation.