Performance assessment of Tao–Mason equation of state: Results for vapor–liquid equilibrium properties

Abstract

The present work evaluates the performance of a molecular-based equation of state in predicting thermodynamic properties of several fluids in a very wide range of temperatures encompassing 100 K < T < 1100 K and pressures ranging from zero to 3200 bar. The theoretical equation of state (EOS) is that of Tao–Mason (TM) which is based on statistical mechanical perturbation theory. The 21 fluids including: argon (Ar), krypton (Kr), xenon (Xe), nitrogen (N 2), oxygen (O 2), carbon dioxide (CO 2), methane (CH 4), ethane (C 2H 6), propane (C 3H 8), normal butane (n-C 4H 10), isobutene (i-C 4H 10), ethene (C 2H 4), benzene (C 6H 6), toluene (C 7H 8) as well as refrigerants consisting of 1,1,1,2 tetra fluoroethane (R134a), tetrafluoromethane (R14), chlorodifluromethane (R22), 1,1,1-trifluoroethane (R143a), 1,1,1-trifluoro,2,2-dichloroethane (R123), octafluoropropane (R218), and 1,1-difluoroethane (R152a) are selected and compared with literature data. The calculations cover the ranges from the dilute vapor or gas to the highly compressed liquid and supercritical regions. The thermodynamic properties are the vapor and liquid densities, the vapor pressure, the internal energy, the enthalpy, the entropy, the heat capacity at constant pressure and constant volume, and the speed of sound. It was found that the overall agreement with literature in all phases especially the vapor/gas phase is remarkable. Furthermore, the Zeno line regularity can be well represented by the TM EOS. Finally, the TM EOS is further assessed through comparing with the Ihm–Song–Mason (ISM) equation of state. In general, the TM EOS outperforms the ISM equation of state.