Multiphase equilibria modeling with GCA-EoS: Part I: Carbon dioxide with the homologous series of alkanes up to 36 carbons

Abstract

The Group Contribution with Association Equation of State (GCA-EoS) has been successfully applied to represent the global phase behavior of carbon dioxide mixtures with alkanes. Using a single set of parameters, the model is able to predict vapor−liquid and liquid−liquid equilibria of binary mixtures not included in the parametrization procedure. Special emphasis was set on describing the transformation between types of fluid phase behavior to reduce the jeopardy of predicting incorrect liquid split. This family of binary systems has been investigated in previous works; however, this is the first time that GCA-EoS was shown to be able to represent the transformation between types of phase behavior as the length of the alkyl chain increases. The model was tested against an experimental database covering C3−C36 alkanes, temperatures from 210 to 660 K, and pressures up to 400 bar. The wide range of conditions and the parametrization strategy are keys to develop a robust thermodynamic tool forpredicting multiphase behavior.