Limitations of the Lee-Kesler equation of state

For mixtures in which the components boil at widely varying temperatures, the accuracy of the Lee-Kesler (LK) equation of state (EOS) diminishes at saturated conditions, near critical regions, and near retrograde regions. Nonetheless, even for widely boiling mixtures, prediction by the LK EOS is much better than by the Curl-Pitzer method, because of the former’s improved correlations for the compressibility factor (Z), the pseudo-critical properties (Pcmix and Tcmix), and the acentric factor (w) of the mixture.

Lee and Kesler used n-octane (C8) as the heavy reference fluid. Therefore, we recommend that you use a method other than the LK EOS to calculate liquid densities of hydrocarbons heavier than C8.