Effect of gas flow channel structure on the performance of an anode-supported honeycomb solid oxide fuel cell

Abstract

An anode-supported honeycomb SOFC gives high volumetric power density and improves thermo-mechanical durability at high temperatures. We have so far fabricated and tested a honeycomb cell with a cathode layer of LSM and an electrolyte layer of 8YSZ on a porous anode honeycomb substrate of Ni/8YSZ. The anode-supported honeycomb cell exhibited promising volumetric power densities. In the present study, current-voltage and current-volumetric power density characteristics of the cells having different flow channel arrangements of the anode and cathode are measured under various inlet hydrogen fuel flow rates to show the effect of three-dimensional transport and distribution of the fuel in the porous anode substrate on the cell performance. We measure ohmic resistances of the honeycomb cells by current interruption method, and indicate the impact of nickel catalyst re-oxidation in the anode substrate by the fuel depletion with the flow channel arrangements resulting in high ohmic resistances and deactivation of the nickel catalyst. In low inlet fuel flow rate, smaller number of the anode flow channel is thereby advantageous, while larger number of the anode flow channel is advantageous in high inlet fuel flow rate. We also discuss suitable flow channel arrangements depending on inlet fuel flow rate to choose an appropriate operation mode.