Flow Pattern and Electrical Conductance on a Planar Solid Oxide Fuel Cell

[摘要] References(9)Cited-By(1)The flow pattern and electrical resistance of a planar solid oxide fuel cell (SOFC) are dependent on the configuration of the cell. Chemical engineering approaches for a continuous tubular reactor with a rectangular cross section were applied to planar SOFCs using a 50 × 50 × 0.2 mm zirconia electrolyte. First, three (front, center and rear) separated anodes were printed on a zirconia electrolyte to investigate the flow pattern. Hydrogen fuel was supplied at rates of between 125 and 1250 mm3/s and the open circuit voltage of the front anode was measured when the back was discharged at 0.5 A. The theoretical voltage of the front was estimated by the Nernst equation using the fuel utilization which was equal to the fraction of hydrogen converted to steam at the back anode. The measured front voltage was in fair agreement with the theoretical value for the fuel utilization between 0.1 and 0.5. This result indicated that the hydrogen flow is approximated by the perfectly mixed model in this range. Furthermore, the dispersed plug flow model was applied. However, the measured voltage that deviated from the perfect mixed model below fuel utilization of 0.1 was ambiguous.The influence of cell configuration on electrical conductance was also investigated. Five planar SOFCs were fabricated using three configurations of separator and two kinds of cathodes. Simulated conductances were derived from a simple model which involves the current paths from the cathode to separator that consisted of rutted paths and ribs. In this model, the generated current in the rutted path flow in the cathode was collected by the edge of the rib and the current was then directly collected at the ribs where the separator touched the cathode. Simulated conductances were adequately correlated with the measured values. The error might be caused by the contact conductance.

[关键词] Zirconia;Fuel Cell;Electrical Resistance;Peclet Number;Reactor Design;Complete Mixing