Simulations of Heat and Mass Transfers in Tubular Solid Oxide Electrolysis Cell

Significant research and development efforts are focused on SOFC (Solid Oxide Fuel Cell) technologies. Thus, these investigations have shown that this kind of electrochemical system could be employed with reversible functions: an electric production in Solid Oxide Fuel Cell (SOFC) mode and a hydrogen production in Solid Oxide Electrolysis Cell (SOEC). A model of a singular cell of an anode support SOEC is proposed. The results of simulations will allow us to understand and to analyze the ionic and electronic ohmic drops effects on the cell performances. This paper proposes a model solution using the CFD-Ace+ software package to simulate the behaviour of this tubular SOEC. Modelling is based on solving conservation equations of mass, momentum, energy, species and electric current by using a finite volume approach on 3D grids of arbitrary topology. The electrochemistry in porous electrodes is described using Butler-Volmer equations at the triple phase boundary. The electrode overpotential is computed at each spatial location within the catalyst layer by separately solving the electronic and ionic electric potential equations. The layout in 3D of the current densities, the electronic and ionic potentials allow the analysis of the respective ohmic drops. The simulation results emphasize the critical behaviour of SOEC such as the endothermic, exothermic and thermo-neutral operating mode. Indeed, it can be observed that the thermo-neutral operating mode exhibits also an internal temperature gradient.