How to Manage Complexity in Phase Equilibria Modeling? Application to the Bunsen Reaction

Abstract

The present work focuses on the thermodynamic modeling of the Bunsen section of the Iodine-Sulfur thermochemical cycle for hydrogen production on the basis of a combination of UNIQUAC activity coefficient and solvation models. The complexity of the material system, two immiscible electrolyte aqueous phases (H2SO4 rich and HIx rich), is managed by defining an equivalent material system able to capture the main physical phenomena. Only the key species involved and their mutual interactions are taken into account, reducing the number of parameters to be estimated from a hundred to only 15. Results show a good agreement with published experimental data, with a better description of the impurities in the HIx phase than in the sulfuric acid phase.