Fundamental study on variable load operation of planar solid oxide fuel cell

The solid oxide fuel cell (SOFC) has a problem in durability of the ceramics used as its cell materials, because its operating temperature is very high and cell temperature fluctuation induces thermal stress to the ceramics. The cell temperature distribution in the SOFC, therefore, should be kept as constant as possible during the variable load operation through the control of the average current density in the cell. Considering this fact, the authors investigate the relation between the average current density and the temperature distribution in the co‐flow‐ and counter‐flow‐type planar SOFC single cells by numerical simulations. In the calculations, the fuel utilization is kept constant and the air utilization is selected as the controllable variable. It is made clear that the change of the temperature distribution can be suppressed to a sufficiently low level and the variable load operation can be realized for both types of cells by properly regulating the air utilization. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(2): 15–24, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20347