On the thermodynamics of liquid propane

Abstract

A non-linear three-centre Lennard-Jones (3CLJ) model is used to simulate propane over the entire liquid region. If one uses the potential parameters recently derived through a thermodynamic perturbation theory by one of the authors, good overall agreement between simulation and experimental data for pressure, residual internal energy, and the derivative quantities heat capacity, adiabatic compressibility and thermal pressure coefficient is found. However, at high densities the simulated pressures are significantly higher than experiment. We demonstrate that the agreement can be greatly improved by readjusting the size parameter σ in the potential by less than 0·5 per cent. It is shown that three-body effects from triple dipole interactions have only a small influence on the thermodynamics of liquid propane. Since these results prove the consistency between experiment, theory and simulation we conclude that the 3CLJ potential used here is an excellent effective pair potential for fluid propane.