New Volume-Explicit Equations of State Based On Statistical-Mechanical Theory

Almost all proposed theory-based equations of state are developed in canonical ensemble (NVT). In chemical engineering applications, however, pressure and temperature are the main specified variables. Therefore, it is more convenient to determine thermodynamic properties from volume-explicit equation of state.  In this work, two new volume-explicit equations of state are proposed based on statistical-mechanical theory. The equations of state are developed by transferring a pressure-explicit equation of state in NVT ensemble to NPT ensemble. The transformation produced two-pair of volume-explicit equations; one for the gas phase and the second for the liquid phase. The new equations of state take into consideration both repulsive and dispersive interactions. The equations are tested to noble gases and short-chain hydrocarbons and show good agreement with experimental data.