Prediction of Critical\nTemperature and Critical Volume\nof Mixtures by a New Group Contribution Method

The vapor–liquid critical properties of mixtures\nare essential\nfor defining the vapor–liquid phase boundary and play a crucial\nrole in predicting various thermophysical properties of mixtures,\nwhich are particularly significant in applications such as supercritical\nextraction and transcritical cycles. While experimental measurement\nis the most efficient and direct approach to obtaining critical properties,\nit is often time-consuming and labor-intensive, necessitating the\nuse of theoretical prediction methods. Nonetheless, existing prediction\nmodels tend to be complex and frequently rely on the critical properties\nof pure substances, which limit their applicability. In this article,\na new group contribution method for predicting the critical temperature\nand critical volume of mixtures is proposed. The new group contribution\nmethod is simple in calculation form, simple in group division, has\ngood accuracy, and does not need the critical temperature and critical\nvolume of pure substances when calculating the critical temperature\nand critical volume of mixtures. This new method includes 24 groups\nand can be applied to systems consisting of organic compounds made\nup of C, H, O, F, Cl, Br, and I elements or CO<sub>2</sub>. The experimental\ncritical temperatures of 272 compounds and 368 groups of binary mixtures\n(3223 data points), as well as the experimental critical volumes of\n224 compounds and 68 groups of binary mixtures (400 data points),\nwere used to determine the group contribution values and model parameters.\nThe average absolute relative deviations (AARDs) for the correlation\nof compounds are 1.28% for critical temperature and 4.93% for critical\nvolume. For binary mixtures, the AARDs are 1.62% for the critical\ntemperature and 7.33% for the critical volume. Additionally, the predictive\ncapability of the new method for critical temperature and critical\nvolume has been evaluated. The AARDs for critical temperature are\n2.48, 1.98, and 0.94% for 25 data points of pure substances, 615 data\npoints of binary mixtures, and 565 data points of ternary mixtures,\nrespectively. For critical volumes, the AARDs are 5.52% for 26 data\npoints of pure substances and 7.49% for 61 data points of binary mixtures.