Application of multiparameter fundamental equations of state to predict the thermodynamic properties and phase equilibria of technological oil fractions

摘要

A new mixture model, explicit in the reduced Helmholtz energy, is proposed for modeling the thermodynamic properties and phase equilibria of technological oil fractions. The model covers a broad temperature and pressure range in gaseous, liquid, and supercritical regions. Based on the given hydrocarbon composition, a complex mixture is modeled by individual substances, which are identified by the acentric factor and critical parameters, while calculations of thermodynamic properties are carried out with use of individual and generalized equations of state. The generalized equation of state for normal alkanes has been used to describe the thermodynamic properties of a seven-component mixture for which there are no individual equations of state. To improve the description of the thermodynamic properties, the binary interaction parameters for ten binary systems were adjusted. The fitting procedure is based on a cubic equation of state with the group contribution and the evolutionary optimization algorithm.