Multi-criteria Optimization for Parametrizing Excess Gibbs Energy Models

Thermodynamic models contain parameters which are adjusted to experimentaldata. Usually, optimal descriptions of different data sets require differentparameters. Multi-criteria optimization (MCO) is an appropriate wayto obtain a compromise. This is demonstrated here for Gibbs excess energy(GE) models. As an example, the NRTL model is applied to the three binarysystems (containing water, 2-propanol, and 1-pentanol). For each system,different objectives are considered (description of vapor-liquid equilibrium,liquid-liquid equilibrium, and excess enthalpies). The resulting MCO problemsare solved using an adaptive numerical algorithm. It yields the Paretofront, which gives a comprehensive overview of how well the given model candescribe the given conicting data. From the Pareto front, a solution that is particularly favorable for a given application can be selected in an instructedway. The examples from the present work demonstrate the benefits of theMCO approach for parametrizing GE-models.

Modelling thermodynamic properties of binary Cu–Eu and ternary Al–Cu–Eu melts

Model calculations of the whole set of thermodynamic properties of liquid alloys for the binary Cu–Eu and ternary Al–Cu–Eu systems have been performed. Authors used the ideal associated solution model (IAS model) for calculation of the entropies and excess Gibbs energies of mixing for these systems. The binaries were given as the Redlich-Kister polynomials. The thermodynamic properties for the ternary system are described using the Redlich-Kister-Muggianu formalism. A comparison of the surfaces of excess Gibbs energy and entropy of mixing for liquid Al–Cu–Eu alloys at 1350 K demonstrates that the ordering related to the formation of rather strong associates in the Al–Eu system significantly affects the concentration dependence of the excess Gibbs energy of mixing in the liquid phase at this temperature.