Limitations of the PSRK method

The Predictive Soave-Redlich-Kwong (PSRK) method has the following limitations:

• The gradient of the Mathias-Copeman alpha function does not have any thermodynamic background; if you extrapolate the alpha function to higher temperatures, the vapor pressure curve tends to diverge.

• The Soave-Redlich-Kwong (SRK) equation of state (EOS) describes the vapor densities of pure components and mixtures quite well, but the deviations of the liquid density predictions are high. In this scenario, we recommend that you use the API method for the liquid density calculations instead.

• For the vapor-liquid equilibrium (VLE) predictions of mixtures with components which have differing sizes, large systematic errors are found.

• This method poorly predicts heats of mixing and activity coefficients at infinite dilution.