An Alternative Method for Correlation and Prediction of Thermo Physical Properties of Fluids-Critical Pressures

Abstract

Based on the linear free energy relationships (LFERs) theory and thermodynamics formulas, an alternative method predicting the critical pressure (Pc) of pure fluids is proposed for the first time. According to the regression result of 15 homologues, 516 substances, correlation equations between Pc and molecular descriptors were obtained. The mean relative deviations (MD) of the 15 equations are from 1.68% to 3.76%. In addition, the squared correlation coefficients (R2) of the most of equations are larger than 0.91. The results reveal that the equations exhibit better effects with a simple form of the equation, high prediction accuracy, definition theory meaning, and wide applicability. This study successfully combines the macroscopic physical properties with the characteristics of molecules and breaks through the experimental or theoretical application scope, while perfecting the calculation of Pc for pure fluids.