Lee and Kesler developed a threeparameter correspondingstates correlation for pure, nonpolar, nonhydrogenbonding fluids—especially, hydrocarbons. Values are provided for


The correlation is based on the BenedictWebbRubin equation of state. For the equation of state, the LeeKesler correlation expresses the compressibility factor Z as a linear function of the acentric factor ω:
Z = Z_{0} + ω Z_{1}
where Z_{0} is the compressibility factor for simple fluids, ω is Pitzer's acentric factor, and Z_{1} corrects Z for the effects of nonspherical intermolecular forces (primarily dispersion and overlap). Similarly, linear expressions are used for residual properties:
h^{res}/RT_{c} = (h^{res}/RT_{c})_{0} + ω (h^{res}/RT_{c})_{1}
s^{res}/R = (s^{res}/R)_{0} + ω (s^{res}/R)_{1}
Once you have values for Z, h^{res}, and s^{res}, then values for all other residual properties can be computed using standard thermodynamic relations. Finally, the correlation estimates the purefluid fugacity coefficient by
ln(φ) = ln(φ)_{0} + ω ln(φ)_{1}
The Macatea calculator will provide values for each of the quantities shown in these equations. For details on the computational procedure, see B. I. Lee and M. G. Kesler, AIChE J, 21, 510 (1975).
To use the correlation, you will need to enter five things about your fluid: