Three dimensional modeling of an solid oxide fuel cell coupling charge transfer phenomena with transport processes and heat generation

Abstract

Fuel cells are promising for future energy systems, because they are energy efficient and able to userenewable fuels. However, there is still a need for improvement and a fully coupled computational fluiddynamics (CFD) approach based on the finite element method, in three-dimensions, is developed todescribe an anode-supported planar solid oxide fuel cell (SOFC). Governing equations are solved forelectron, ion, heat, gas-phase species and momentum transport, and implemented and coupled to kineticsdescribing electrochemical reactions.It is shown that the heat generation due to the electrochemical reactions results in an increased tem-perature distribution and further current density along the main flow direction. This increase is limiteddue to the consumption of electrochemical reactants within the cell. For cases with a high current den-sity generation, the resistance to electron transport and the oxygen gas-phase flow is high for positions(within the cathode) under the interconnect ribs, which gives a high current density gradient in thedirection normal to the electrode/electrolyte interface. The increase in the current density is acceleratedby an increased temperature along the main flow direction, due to the strong coupling between thelocal current density and the local temperature. It is shown that an increase of the anode active area-to-volume ratio with a factor of two transfers around 20 mV of (activation) polarization from the anode tothe cathode side, for the case investigated in this study. © 2013 Elsevier Ltd. All rights reserved.