Chao-Seader

The Chao-Seader method (CS) was one of the first attempts to more rigorously calculate the composition effect on thermodynamic properties of mixtures. The method is a combination of rigorous and empirical techniques as follows:

$image\EDIT03.gif$ The vapor fugacity coefficient is computed with the Redlich-Kwong equation.

$image\EDIT03.gif$ The liquid activity coefficient is computed from the Scatchard-Hildebrand equation which is based on regular solution theory.

$image\EDIT03.gif$ The fugacity coefficients for the liquid are computed using the framework of Pitzer's principle of corresponding states as a function of reduced temperature, reduced pressure and the acentric factor. The liquid fugacity curves were developed from data for light hydrocarbons typically encountered in natural gas processing.

More information on this method, see "Chao-Seader (CS)" under "Generalized Correlation Methods" in Chapter 2, Volume 1 of the PRO/II Reference Manual.

Application Guidelines

Light hydrocarbons at temperatures less than 500 degrees F and pressures less than 1500 psia. Not recommended for systems with large concentrations of H2 or other non-hydrocarbons.