Models representación de los equilibrios líquidos multifásicos de sistemas cuaternarios con los modelos NRTL y UNIQUAC

The modeling of multiphase liquid equilibria for quaternary systems using the activity coefficient models NRTL and UNIQUAC is presented. The numerical procedure used to calculate the multiphase liquid equilibria of these systems is based on the minimization of the system Gibbs energy in conjunction with thermodynamic stability tests to find the most stable state of the system. The algorithms presented to estimate the binary interaction parameters of the NRTL and UNIQUAC models were applied to the correlation of the experimental data for two quaternary systems with two and three liquid phases in equilibrium. The agreement between experimental equilibrium data and those calculated with both models was satisfactory for the two systems studied.