Computational Modeling of Planar SOFC: Effects of Volatile Species/Oxidant Mass Flow Rate and Electrochemical Reaction Rate on Convective Heat Transfer

Abstract

A three-dimensional computational simulation of an intermediate temperature planar, tri-layered solid oxide fuel cell is considered for steady incompressible fully developed laminar flow in the interconnect ducts of rectangular cross section, with uniform supply of volatile species (80% H2 + 20% H2O vapor) and oxidant (20% O2 + 80% N2) at the electrolyte surface. The governing equations of mass, momentum and energy conservation coupled with that for electrochemical species are solved computationally. The Darcy-Forchheimer model described the fuel and oxidant transport through the porous electrodes, where the flow is in thermal equilibrium with the electrolyte matrix. The anode-side triple phase boundary is computationally resolved to capture the electrochemical reaction that results in current and volumetric heat generation. Parametric effects of the interconnect design (contact area and channel size) on the variation of thermal-hydrodynamic and electrical performances of the cell are presented. These highlight the effect of the flow rate on the Nernst potential and, in turn, the variations in current density, temperature and mass/species distributions, flow friction factor, and convective heat transfer coefficient. Interconnect channels of different cross-section aspect ratio (width/depth ∼ 0.5–2.0) with electrode-interface-contract half widths for minimum and unchanged area specific resistance) are contrasted so as to evaluate the optimal overall electrical and convective cooling performance of the planar anode-supported SOFC.