Vapor-liquid equilibrium calculations of pure compounds from a hard-sphere-chain equation of state: The structure effect

An equation of state for pure fluids including hydrocarbons such as chain - like molecules and ring compounds, alcohols and ketones is developed by combining a reference equation for hard-sphere-chain fluids established by Hu et al. and perturbation term proposed by Sadowski. This perturbation equation, however, is obtained by a rough approximation and therefore, only can be admitted by introducing another model parameter that scales the non-ideal behavior of several types of fluids. In this study, the structure parameter, zeta(KB), is introduced and determined according to the type of molecular structure and intermolecular forces. We examine the proposed model to various chemical structures of fluids such as normal alkanes, cycloalkanes, aromatic rings, ketones, and alcohols. Theoretical calculations for the vapor-liquid equilibria of pure fluids show good agreement with the experimental data. Each chemical structure has its own values of zeta(KB). (c) 2005 Elsevier B.V. All rights reserved.