A new non-cubic equation of state based on molecular thermodynamics has been developed by considering cell theory and forming the potential energy of a system from the volumetric average of the van der Waals type and the 15-6 Mie type potential energies. The proposed equation has four constants and requires knowledge of the critical temperature, the critical pressure, the critical volume, the excluded volume and an additional parameter to characterize any given fluid. The new equation yields good agreement with experimental saturation properties of 29 non-polar and 16 polar substances from reduced temperatures of 0.5 to the critical temperature. The new equation exactly fits the critical point, generally gives better predictions of liquid volumes than, and predictions of vapor pressures and heats of vaporization equally as good as commonly used cubic equations, and yet only requires two fitting parameters.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry