Application of model-free computation techniques and limiting conditions for azeotropy. An additional assessment of experimental data

The model-free computation technique of Mixon et al. is explored as a complementary tool for the assessment of vapor-liquid equilibrium (VLE) data and for further analysis of binary systems that satisfy standard consistency tests but are not satisfactorily modeled by classical G^E expressions. A numerical procedure is suggested that avoids the use of empirical activity coefficient models by generating vapor phase compositions, activity coefficients and G^E values directly from [T, P, x] data. Important features regarding azeotropy in systems that deviate positively from ideality are discussed and it is shown how these features may influence the proposed calculation method when experimental data are considered.