The Direct Method and Equations of State for Hpvle Computation
J. David Raal, Andreas L. Mühlbauer · 2023
This chapter reviews the equations of state (EOS) of greatest significance in high-pressure vapor-liquid equilibrium (HPVLE) computation, including the virial and complex virial EOS, traditional cubic EOS, their modifications and mixing rules for application to mixtures, and the perturbed theory EOS. An EOS can be used to determine the vapor pressures, critical properties, and densities of pure substances and their mixtures in addition to their use in vapor-liquid equilibrium data calculations. The traditional thermodynamic cubic equations of state are popular because of their relatively simple computational procedures. They are generally capable of supplying sufficiently accurate thermal property and vapor-liquid equilibrium information for nonpolar and slightly polar systems at moderate to high pressures except for the critical region. Real gas molecules, versus an ideal gas molecule, have a finite size and by their very nature possess rotational, vibrational, and potential energies in addition to translational energy.