ON THE CALCULATIONS OF AZEOTROPES FROM THE NRTL AND UNIQUAC MODELS

The local composition models of NRTL and UNIQUAC have been used in pre dicting of azeotropic data for binary and ternary liquid mixtures of v arious types. Activity coefficients have been calculated using the tem perature dependent parameters of the models. In order to avoid the con vergence problem of Newton's method due to initializing the unknowns,t he step controlled Newton's method has been used. The results show tha t the performance of the UNIQUAC model is slightly better than that of the NRTL model. However the performances of the models change from on e mixture to another.