Molecular modeling of systems related to the biodiesel production using the PHSC equation of state

Abstract

In this study, capability of the Perturbed Hard Sphere Chain (PHSC) equation of state (EoS) is investigated for thermodynamic modeling of binary and ternary systems related to the biodiesel processing. Vapor-liquid, liquid-liquid and solid-liquid equilibria (VLE, LLE and SLE, respectively) in mixtures containing fatty acid alkyl ester, non – polar and polar compounds are investigated. The PHSC model parameters are calculated for both fatty acid methyl ester (FAME) and Fatty acid ethyl ester (FAEE) molecules by fitting on the experimental pure liquid density and vapor pressure data. Using the obtained parameters, the phase behavior of binary systems over wide range of thermodynamic conditions is studied. The average deviation between model calculations and experimental equilibrium data of water + ester, alcohol + ester, ester + ester, hydrocarbon + ester and carbon dioxide + ester systems are about 5.57, 2.42, 0.31, 3.61 and 6.45%, respectively. Furthermore, the capability of the model has then been assessed by prediction of LLE phase behavior of ternary systems. The results show that, the predicted and correlated results are in good agreement with the experimental data. In the case of SLE, the melting and eutectic points of fatty acid ester systems have been predicted over wide range of composition.