CFD modeling and simulation of proton-conducting solid oxide electrolysis cell for electrochemical hydrogen sulfide decomposition to produce hydrogen

Abstract

Electrochemical hydrogen sulfide decomposition produces hydrogen by recovering hydrogen sulfide using electrical energy. Adopting proton-conducting solid oxide electrolysis cell for electrochemical hydrogen sulfide decomposition carry out hydrogen production and separation in a single step. Electrochemical hydrogen sulfide decomposition technology is still in the stage of developing electrodes. Computational fluid dynamics (CFD) models of electrochemical cells are mandatory to improve the cell performances and efficiency because the CFD model increases an understanding of mass and heat transport and electrochemical mechanisms. Especially for electrochemical hydrogen sulfide decomposition, there is a thermal decomposition through the cell. Therefore, it is important to figure out interactions between electrochemical and thermal decompositions. However, studies on CFD models for electrochemical hydrogen sulfide decomposition are lacking. In this study, a CFD model for electrochemical hydrogen sulfide decomposition is developed on a button cell scale based on experiments using an open-source CFD software, OpenFOAM®. The model implements porous electrodes and electrochemical properties with the Nernst equation and Faraday's law of electrolysis. Thermal properties found in experiments at 600 °C are also implemented by kinetic estimation through the experiment results. The model is validated by comparison of the current density-voltage curve and conversion of hydrogen sulfide with the experiment results. Case studies are carried out to investigate cell variables such as current density, conversion of hydrogen sulfide, electrochemical versus thermal reaction ratio by inlet mole fractions, flow rates, and flow configurations.