Collect. Czech. Chem. Commun. 1992, 57, 1424-1438

Influence of the Thermophysical Properties Extrapolation, in the Course of Iterative Calculations, on the Convergence Characteristics of Higher Level Simulation Algorithms - A General Analysis

Stefan G. Tsvetkov and Roumiana P. Stateva

Institute of Chemical Engineering, Bulgarian Academy of Sciences, acad. G. Bontchev str., bl. 103, Sofia 1113, Bulgaria


An extrapolating model provides values for thermophysical properties when infeasible specifications (either pressure or temperature) are recognized at a given iteration in process simulator, applying an EOS technique. The model has a considerable effect on the convergence characteristics, accuracy and robustness of a higher level simulation algorithm. The present paper outlines a strategy for evaluating and comparing the abilities of different extrapolating techniques: to promote the convergence of higher level algorithms; to ensure for them a solution, which will be of accuracy, not significantly inferior, to the actual one. The latter could have been obtained using for example a different thermodynamic model.