Vapor-liquid equilibrium of binary systems with EoS/GE models at low pressure: Revisiting the Heidemann-Kokal Mixing Rule

Abstract

In this work, a ϕ-ϕ approach is tested in the description of vapor-liquid equilibrium of 18 different binary systems by means of EoS/GE type models. These models combine the potentialities of the Peng-Robinson cubic equation of state and the UNIQUAC local composition model. The focus is on the Heidemann-Kokal Mixing Rule, whose derivation is presented. Systems including nonpolar - nonpolar, weakly polar - weakly polar, water - weakly polar, nonpolar - weakly polar, weakly polar - strongly polar and strongly polar - strongly polar compounds, besides systems involving immiscible components and carboxylic acids, were evaluated. Binary interaction parameters of the UNIQUAC model were estimated using a stochastic particle swarm algorithm, coupled to a Quasi-Newton deterministic algorithm. As a result, average deviations of less than 2% and 1% were obtained for vapor phase composition and bubble temperature or pressure correlation, respectively. The proposed modeling was efficient in the treatment of all evaluated systems and appears as a good alternative for the development of new models.