Rectilinear Diameter for Saturated Vapor and Liquid Enthalpies at the Coexisting Phases of Pure Substances and Mixtures


Khalid Farhod Chasib*, Basma Mohammed Kadhim


Petroleum & Gas Engineering Department College of Engineering, University of ThiQar, Iraq.

Corresponding Author Email: [email protected]

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

For mixtures and pure substances at the coexisting phases to express the saturated liquid and vapor enthalpies, Rectilinear Diameter principle is adopted as new criteria in this study. At the corresponding temperatures another relation is requires to calculate the vaporization enthalpies. For numerous pure substances, the correlations between pressure and saturated liquid and vapor enthalpies are investigated. These investigations exhibit that the enthalpies of saturated liquid and vapor cannot be represent as an easy general correlation. For mixtures and pure substances, modern easy correlations have been developed. Rectilinear Diameter principle reliant on the law of corresponding states is the base of these correlations. By fitting of experimental values for twenty pure substances out of thirty, the second relation developed using Maximum Likelihood Principle and then successfully applying to the remaining components, which point out the correlation generality. Up to the critical region can apply successfully of these correlations. The values of normal boiling point temperature, critical temperature and enthalpies of vaporization (by any suitable correlation), these values are requires to use this method. At the saturation region, the proposed method accuracy is superior to that of Lee and Kesler. Compares with Lee and Kesler method, the present correlations are simpler, easier and straight forward. Further developed of these correlations to be used for processes involves condensation phenomena, vaporization and design purpose of distillation operations.