Regression Of UNIFAC Group Interaction Parameters And The Applications In Vapor-liquid Equilibra

The group interaction parameter a mn and a nm, are not functions dependesd on temperature in original UNIFAC model, and just the constants. The suitable temperature ranges are very narrow. In order to adapt the uninterrupted development of chemical industry, Gmehling (Dortmund) had brought forward the new improvement to the model and had established the DDB data base (Dortmund data bank), but the parameters'matrix is not perfectly. So, the further study is very important. In this paper, the prediction model of HVOS-PR/MDUNIFAC has been proposed by using PR Equation of state, MDUNIFAC activity coefficient combined with the mixing rule of HVOS.In order to make the parameters'matrix more perfectly, the vapor-liquid phase equilibrium data of seven binary systems include Pyridine/1-Chlorobutane, Pyridine/1, 1-Dichloroethane, Pyridine/Acetic, Tetrahydrofuran/Cyclohexane, Pyridine/Chloroform, Pyridine/Ethyl bromide and Cyclohexane/Trichloroethylene have been measured in this paper, and the thermodynamic consistency checks have been made. And those binary vapor-liquid equilibrium data were applied to the regression of group interaction parameters.The group interaction parameters for 15 group combinations were refitted with Nelder-Mead simplex method by predicting 33 binary vapor-liquid equilibrium systems (2727 experimental data,the data from the seven binary system which have been determined in this paper,"Center of tsinghua membrane's Database"and "scientific Database"). Additionally, 17 new group interaction parameters were fitted by 22 binary vapor-liquid equilibrium systems (1039 experimental data, the data from the"Center of tsinghua membrane's Database"and"scientific Database'); the parameters wer applied to predict the vapor-liquid equilibria for 28 binary systems(739 experimental data) at different temperature and pressure to test the accuracy of modified and supplemented group interaction parameters. Compared results calculated by using this new parameters and original parameters with the experimental data, it shows that the new parameters are much better than original parameters in these systems include alcohol and acid none-polar. The absolute deviation of vapor-composition is less than 0.05 and the relative deviation of bubble-pressure is less than 6%; the results of prediction for the binary and ternary water-polar systems were improved slightly because of the existing hydrogen-bonding and association effect for polar systems with water.According to the result, the original MDUNIFAC group interaction parameters matrix and the range of application of this model are extended. The new group interaction parameters in this paper were proved that have important practical application values in chemical reaction engineering, separating engineering and chemical engineering processes.