Thermodynamic properties of hydrocarbons and fluorocarbons using the SAFT equation of state

Abstract

The necessary analytical derivatives of SAFT have been taken and a computer code has been developed to calculate phase equilibria and other thermodynamic properties such as enthalpy, entropy, heat capacity, velocity of sound and compressed liquid density. Although SAFT had been previously used to fit phase equilibria, no other study has attempted to simultaneously model thermal properties. The ability of SAFT to model phase equilibria and these other thermodynamic properties with a single set of parameters is examined. It is determined that SAFT predicts phase equilibria well, but does not do as well in predicting the other thermodynamic properties. Modified versions of the SAFT equation of state such as SAFT-Dimer and SAFT-Lennard-Jones are applied to improve the predictions of thermodynamic properties. No significant improvements in the phase equilibria results are observed. Monte Carlo simulations in Isothermal-Isobaric ensemble are performed to confirm the results for a Ring equation of state (15). SAFT and the Ring equation predict similar results for benzene and toluene.