Comparison of SAFT-VR-Mie and CP-PC-SAFT in predicting phase behavior of associating systems II. Ammonia – Hydrocarbons

This study compares the accuracies of CP-PC-SAFT and CS-SAFT-VR-Mie in the entirely predictive estimation of the available data on ammonia-hydrocarbon systems. The nitrogen(1) – ammonia(2) and R1234yf(1) – ammonia(2) systems are considered as well. CS-SAFT-VR-Mie is also implemented for predicting phase equilibria in the aqueous systems of aromatic hydrocarbons and compared with the previously published results of CP-PC-SAFT. Both approaches comprise predictive parametrization schemes for the non-associative compounds replacing the fitting procedures. In all the cases k₁₂ = 0 along with a universal value of ε^cross = 0.6 ε^AB for the systems of aromatic compounds are used. It is demonstrated that despite the differences between their molecular assumptions and parametrization strategies, these models can be characterized by a comparable over-all accuracy, while CP-PC-SAFT is advantageous in estimating the global phase behavior. Nevertheless, both models could be assumed as reliable enough for raw predictions of the unavailable data in the considered systems. Bearing in mind the fact that all parts of the thermodynamic phase-space are closely inter-related, the current results could rather be attributed to the realistic values of co-volume along with the capability of the considered models to describe the critical and sub-critical pure compound data simultaneously, than to a profundity of their molecular backgrounds.