The main objectives of the planned research work are:
- extensive examination of the current group interaction parameters using the Dortmund Data Bank (DDB) in connection with graphical representations
- revision of the existing group interaction parameters using new experimental results from systematic measurements and the currently available data banks
- filling gaps in the existing parameter tables (UNIFAC, Modified UNIFAC (Dortmund) and PSRK)
- introduction of new groups (cyclic thioethers, imidazole, morpholine ...)
- introduction of more flexible groups (e.g. cyclic sulfides, aromatic ethers, nitriles, sulfides, n-formylmorpholine, Hg, polyethylenglycol, pyrrole, glycerol, thionyl, urethane...)
- consideration of proximity and isomeric effects
For this research work besides a large data base a large number of systematic experimental investigations are necessary to fill gaps in the matrices and to revise group interaction parameters. The systematic measurements should increase the data base with supporting experimental data for fitting reliable temperature dependent group interaction parameters. Besides data for vapor-liquid equilibria in particular activity coefficients at infinite dilution, azeotropic data, solid-liquid equilibria of eutectic systems and heats of mixing data at high temperatures (90 and 140 oC) are measured.
DDBST GmbH, responsible for the update of the Dortmund Data Bank (DDB), kindly agreed to support the planned research work by supplying the current version of the Dortmund Data Bank, this means all the phase equilibrium information published in literature. At the first sponsor meeting the representatives also agreed to provide internal company data exclusively for the planned model development work.
At the Chair of Industrial Chemistry at the University of Oldenburg very reliable experimental facilities (in many cases computer driven) have been built up, which are used for the various experimental investigations (VLE, hE, SLE, azeotropic data). Furthermore a sophisticated software package was developed within the last 28 years, which simplifies the fitting of the group interaction parameters. Although a great part of the required preliminary work for a successful completion of the comprehensive research project has already been performed, a constant preoccupation of Consortium is to obtain more reliable parameters. Following this objective, a new software with an user-friendly interface for fitting the parameters for mod. UNIFAC and original UNIFAC is developed by DDBST. The particular features of this program allow the enhancing the model flexibility by considering multiple group-group interaction sets in optimization and by taking into consideration a larger spectrum of data. Multiple standard and deviation diagrams allow simple quality judgment and weighting or removal of data sets. Same data base management for original UNIFAC and mod. UNIFAC is enabled.
The following table shows the available group interaction parameters for the model Modified UNIFAC (Dortmund) 2017
* in the meantime 291 of the already published group interaction parameters have been revised within the consortium.
For a dynamic visualization of the development you may access the following link: