A consistent three-parameter cubic EOS for precise prediction of volumetric and saturation properties through wide-temperature-ranged adjusted critical compressibility factor

Abstract

Equations of state (EOS) have always been an area of focus in a profusion of studies for which myriads of researchers are continuously developing novel improvements and optimizations, especially to be more adequately employed in the chemical and petroleum industries. Although EOSs with two parameters suffice to predict the vapor pressure (Psat) and phase equilibria, incorporating the third parameter will mainly enhance the estimation of saturated liquid density (ρl,sat) in a company with reliable Psat. Such a process causes the emergence of a component-dependent critical compressibility factor for which the investigations have revealed that the use of its adjusted value (ηc) will remarkably reduce estimated ρl,sat deviations. Researchers have proposed various formats of ηc, either a constant value for all temperatures or variable/piecewise function in the vicinity of the critical point. In the current study, a brand-new cubic EOS is proposed in which ηc is found to be a polynomial function of temperature, for a range extended to a lower limit of normal boiling point. A database of 2142 pure components is employed to compare the performance of the proposed EOS relative to two- and three-parameter EOSs. Results indicate that the EOS provides magnificent predictions of saturation pressure and saturated liquid density without implementing the volume-shift correction with average deviations of 0.78% and 0.75%, respectively. Finally, the performance of the proposed EOS is examined by predicting the densities of 133 binary mixtures with 0.52% average error, almost four times less than the best estimations of other EOSs.