In a four part series of papers Koppany modified the original van der Waals equation by making it a three parameter dependent (Tc, Pc, w) equation of state where w is the well known Pitzer acentric factor. This work was done in order to make the VDW equation better predict pure component vapor pressures and mixture vapor-liquid equilibria.
In this second paper of a two part series we show detailed graphical comparisons between reduced vapor pressures (PRSat vs TR) generated from the modified van der Waals equation and actual experimental data for a series of selected hydrocarbons and non hydrocarbon gases covering a range of acentric factors up to nearly 0.50. The modified VDW predictions are also graphically compared against the PRSat versus TR curves independently generated from the three-parameter Lee-Kesler correlation for the same components considered above.