Development of the NRTL functional activity coefficient (NRTL-FAC) model using high quality and critically evaluated phase equilibria data. 1

Abstract

The non-randomness two-liquid model (NRTL) has been used successfully in chemical engineering to calculate phase equilibria. Different forms of the NRTL model have been developed, including original NRTL, electrolyte NRTL (e-NRTL), polymer NRTL and segment based NRTL (NRTL-SAC). The mentioned forms of the NRTL model are correlative so that they require experimental data to regress the NRTL interaction parameters, which in turn, limit the application of the NRTL models. In the current study, therefore, the NRTL functional activity coefficient (NRTL-FAC) model was developed based on the high-quality experimental vapor-liquid equilibrium (VLE) data. The quality of experimental data were checked using different thermodynamic consistency tests, including Herington test, Van Ness test, point test, infinite dilution test, EOS test and endpoint test. Of the available VLE data, 2938 isothermal/isobaric data sets including 46,651 data points were used in the development of the model. Besides, 137 molecules with 50 main groups were used to develop the NRTL-FAC model. The Stavermann-Guggenheim term was also used to account the combinatorial contribution of the NRTL-FAC model. The good agreement between the predicted results by the NRTL-FAC and the experimental VLE data is encouraging. The present model performs superior to the previous versions of the UNIFAC model.