A MODIFIED UNIFAC MODEL .2. PRESENT PARAMETER MATRIX AND RESULTS FOR DIFFERENT THERMODYNAMIC PROPERTIES

Several years ago a modified UNIFAC (Dortmund, FRG) method was proposed, which shows various advantages when compared with the group contribution methods UNIFAC or ASOG; the latter are used worldwide for the synthesis and design of rectification processes. These advantages were reached by using a modified combinatorial part and by using a large data base to fit temperature-dependent group interaction parameters simultaneously to vapor-liquid equilibrium (VLE), liquid-liquid equilibrium (LLE), h(E), and gamma(infinity) data. The main advantages of the modified UNIFAC method are a better description of the temperature dependence and the real behavior in the dilute region and that it can be applied more reliably for systems involving molecules very different in size. To increase the range of its applicability, the temperature-dependent group interaction parameters of the modified UNIFAC have been fitted for 45 main groups using phase equilibrium information (VLE, h(E), gamma(infinity), LLE) stored in the Dortmund Data Bank. A comprehensive comparison with the results of other group contribution methods confirms the high reliability of the modified UNIFAC (Dortmund) method.