Second-order thermodynamic derivative properties of binary mixtures of n-alkanes through the SAFT-CP equation of state

Abstract

An analytic version of statistical associating fluid theory (SAFT), the so-called SAFT-CP (critical point) equation of state [J. Chen, J.-g. Mi, Fluid Phase Equilib. 186 (2001) 165–184], has been developed to predict the second-order thermodynamic derivative properties of n-alkane in the wide density and temperature ranges [A. Maghari, M.S. Sadeghi, Fluid Phase Equilib. 252 (2007) 152–161]. In this work, we have extended the SAFT-CP model to predict some main derivative properties of binary mixtures of n-alkanes, including speed of sound and heat capacities. The proposed extension is based on the average segment number and shape parameter for a pair in a mixture of hard convex bodies and the classical Lorentz–Berthelot combining rule for segment size and energy is employed. The SAFT-CP model is found to be able to correctly describe the second-order thermodynamic derivative properties as well as pVT properties of binary mixtures studied in this work.