Equations for the Regular Solution Model method

The activity coefficient expression is:

where:

niL is the liquid molar volume of component i

di is the solubility parameter of component i

There are no adjustable parameters in the regular solution model. It is useful for mixtures of nonpolar components, but it should not be used for highly non-ideal mixtures, especially if they contain polar components. Solubility parameters have been tabulated for numerous compounds, and these parameters are included for most components in the library.