Crossover VTSRK equation of state for selected alkane + alkane and CO2 + alkane binary mixtures

• The crossover VTSRK EoS for binary mixtures was developed based on the isomorphism approximation.
• The crossover VTSRK EoS needs only one binary interaction parameter to predict VLE and pρT properties.
• The crossover EoS gives better VLE and pρT representations than the VTSRK EoS in the critical region.

Accurate predictions of the thermodynamic properties of binary mixtures, especially in the critical region, are essential for many chemical process designs. In this study, based on the predictive crossover volume translation SRK equation of state (VTSRK EoS) presented in previous work, the crossover VTSRK EoS for binary mixtures was developed. Composition-dependent mixing rules with one adjustable binary interaction parameter, kij, were used for the crossover equation to simplify the crossover EoS. The applicability of the crossver EoS was verified against two kinds of binary mixtures, including alkane + alkane and CO2 + alkane mixtures, because of their wide applications. For the alkane + alkane mixtures with similar intermolecular interactions, the kij in the vdW-1 mixing rules was set to zero which makes the calculation predictive. For the CO2 + alkane mixtures which have large difference between intermolecular interactions, the vapor liquid equilibrium (VLE) and single phase pρT properties were calculated using kij obtained from VLE or pρT experimental data at one temperature. The crossover VTSRK EoS gives better VLE and pρT representations than the VTSRK EoS, especially in the critical region.