A modified Patel–Teja cubic equation of state: Part I – Generalized model for gases and hydrocarbons

A generalized cubic equation of state is proposed for non-polar substances, including heavy hydrocarbons. The new model is based on the Patel–Teja cubic equation of state and the alpha function of Heyen. The proposed equation is compared with the Peng–Robinson, the Peng–Robinson–Gasem, the original Patel–Teja and the translated Peng–Robinson model proposed by Ahlers and Gmehling. Results show that the model proposed in this work is the best of the models evaluated to represent the saturated thermodynamic properties of non-polar substances, especially in the cases of heavy hydrocarbons and hydrogen. The new model improves the capability of the Patel–Teja equation to predict the second virial coefficient and the Boyle temperature of gases and hydrocarbons. Finally, some generalized expressions are developed to predict the vapor liquid equilibria for aromatic/alkane and aromatic/aromatic system using the proposed model and the Wong–Sandler mixing rules.