estimation of uniquac-nrf model parameters for nh3-co2-h2o system

vapor-liquid equilibrium in nh3-co2-h2o system at high pressures has been studied. the uniquac-nrf model for this system was extended by using the goppert 4 maurer reported datas. since the system contains molecules and ionic species the binary interaction parameters considered, where those are of molecule-molecule, molecule-ion and ion-ion types. these interaction parameters are taken as constant values in uniquac-nrf, which are not accurate. in this work the mentioned parameters have been considered as function of temperature in quadratic form. by applying an optimization mathematical program to the uniquac-nrf model and experimental data reported by goppert and maurer the model parameters were obtained in term of temperature. the results of  this model with the new parameters show good agreement with experimental data.