Influence of Radial Flows on Power Density and Gas Stream Pressure Drop of Tubular Solid Oxide Fuel Cells

The development of solid oxide fuel cells (SOFCs) for powering vehicles requires high power densities. The radial flows generated by the insert structures in SOFC fuel channels could improve the power density by facilitating the fuel to enter the porous anode for electrochemical reactions. In this paper, we developed a 2D axisymmetric numerical model to examine the influence of a convergent conical ring insert on the flow and mass transfer characteristics in a tubular SOFC. The mass transfer conductance of fuel was analyzed and proposed to quantify the performance of different insert designs. The effects of the radius and offset angle of the convergent conical ring insert were examined and analyzed. We demonstrate that increasing the insert radius could increase the fuel mass transfer conductance and effectively improve the net output power of the tubular SOFC by 12% while the offset angle of the inserts exhibits a negligible impact on the fuel mass transfer conductance. Increasing the offset angle could help reduce the gas-phase pressure drop in fuel channels by 42%. The present study helps improve our understanding of the relationship between fuel mass transfer conductance and electrochemical reactions. It also proposes channel design methods based on mass transfer conductance for high-power-density solid oxide fuel cells.