Generalized f/P, Z T and Z P values for liquids at low reduced temperatures

The three‐parameter correlation of Pitzer et al. for fugacity coefficients ( f / P ) has been extended to liquids in the 0.5 ≤ T r ≤ 0.8 and 0.2 ≤ P r ≤ 9.0 region. In addition, values of the derivative compressibility factors Z T and Z P have also been obtained in the same region. This extension is based on the generalized correlation of the compressibility factor Z recently reported. The isothermal coefficient of bulk compressibility β T compiled by Rowlinson has been employed with the pressure effect on β T taken into consideration. The correlation for f / P obtained in this work is compared with that of Curl and Pitzer at T r = 0.8, Chao et al. at T r from 0.50 to 0.70, and that of Carruth and Kobayashi in the 0.50 ≤ T r ≤ 0.64 region. Using the tabulated Z P and Z T values \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{H^* - H}}{{T_c }},{\rm }\left ({\frac{{\partial V}}{{\partial P}}} \right)_T $\end{document} , and \documentclass{article}\pagestyle{empty}\begin{document}$ \left ({\frac{{\partial V}}{{\partial T}}} \right)_P $\end{document} have been calculated and compared satisfactorily with the corresponding values derived from literature data. In addition, a correlation of vapor pressures of both hydrocarbons and nonhydrocarbons is also presented. The agreement between this correlation and those reported by Pitzer et al. and Carruth and Kobayashi is very satisfactory.