Unified thermodynamic modelling of diffusion and thermodiffusion coefficients

The paper discusses a new approach to thermodynamic modelling of transport coefficients in mixtures, responsible for diffusion and thermodiffusion. A new theoretical framework (A. Shapiro, J. Non-Equilibrium Thermodyn., 45 (2020), 343) expresses these values in terms of the new quantities, penetration distances and emission functions, that may be determined thermodynamically. The goal of the present work is to verify the theoretical scheme by application to the available experimental data on transport coefficients. A consequence of the theory is that the parameters fitted to the values of diffusion coefficients may be applied for prediction of thermodiffusion coefficients. The accuracies of fitting and prediction is verified in the present work. To do so, the theory is simplified for the case of binary mixtures, and the explicit formula for the coefficients are derived. The results indicate good qualitative and, for the most cases, quantitative behaviour of the model, although some problems remain. (C) 2022 The Author(s). Published by Elsevier B.V.