The modified UNIFAC model Dortmund

The UNIFAC model diseussed in the previous section does suffer from a number of shortcomings, particularly for values of the activity coefficients in infinite dilution, the enthalpies of mixing and the values obtained for highly-asymmetrical systems. In order to improve the data, adjustments were made in three directions (1987)  

Obviously, the consequence of this is the provision of four extra parameters per pair and c ). 

All of these improvements were brought together in the creation of a new model, called the Dortmund modified UNIFAC model, which is characterized, for each binary system, by four structural parameters and six energy parameters contained in a database. 

The UNIFAC consortium also gives its subscribers a piece of software capable of calculating various thermodynamic values on the basis of the model and its database. 

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