GAUSSIAN-LIKE VOLUME SHIFTS FOR THE PENG-ROBINSON EQUATION OF STATE

The original form of the Peng-Robinson (PR) cubic equation of state do es not predict liquid densities that are accurate enough to be used fo r process calculations. Liquid densities predicted by the PR equation have been improved by incorporating a Gaussian-like volume translation which is a strong function of temperature near the critical point but becomes a constant value away from the critical point, without any di scontinuities in the critical region. This simple method provides liqu id densities for 283 nonpolar, polar, and hydrogen-bonding fluids with an overall average absolute deviation of 0.70%, which compares favora bly with existing volume translation and dedicated liquid density calc ulation methods.