Abstract
In this work volume-translated Peng–Robinson group contribution equation of state was used to calculate excess enthalpies. Four model systems were selected with the purpose to compare experimental and predicted enthalpy values at different temperatures. After the calculations were performed in Matlab software, results were verified with free software tool of Dortmunder Datenbank (DDB). In a next step, the mixing process and interaction forces were described on the basis of the sign and course of enthalpy values. The endothermic behavior of three systems could be well predicted, while for the most polar system, predictions were less precise. Furthermore, the discrepancy between experimental data from the literature and predicted values was discussed to evaluate the accuracy of the selected model. Lowest mean deviations (<75 J/mol and <15% at all temperatures) could be stated for alkane/benzene mixtures, while highest deviations could be again observed for the most polar mixture. Although the magnitude of deviations was in agreement with the literature, it could be shown that the selected temperature is of major importance for the quality of predictions. Furthermore, a review of different literature values for the n-hexane/benzene system could reveal that the reliability of experimental data has to be carefully checked.
Highlights
In order to design thermal separation processes, the knowledge of fundamental thermodynamic properties as well as equilibria conditions is necessary
While in the first years a focus was set on a good description of vapor liquid equilibria, the model was continuously improved in order to describe excess enthalpies and activity coefficients with a satisfying accuracy as well [3]
To obtain the results for excess enthalpy, a program code was written in Matlab analysis software, which is built of four important parts: 1
Summary
In order to design thermal separation processes, the knowledge of fundamental thermodynamic properties as well as equilibria conditions is necessary. While in the first years a focus was set on a good description of vapor liquid equilibria, the model was continuously improved in order to describe excess enthalpies and activity coefficients with a satisfying accuracy as well [3]. The treatment of supercritical compounds and the prediction of other thermodynamic properties (gas solubilities, enthalpies, densities, heat capacities) is not possible with activity coefficient models [2,3,5]. For this purpose, the group contribution concept was extended to equations of state, and in 1991 the predictive
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