Numerical analysis of output characteristics of tubular SOFC with internalreformer

a the solid oxide fuel cell (SOFC) system, the internal reforming of raw fu el will act as an efficient cooling system. To realize this cooling system, a special design of the internal reformer is required to avoid the inhomog eneous temperature distribution caused by the strong endothermic reforming reaction at the entrance of the internal reformer. For this purpose, a tubu lar internal reformer with adjusted catalyst density can be inserted into t he tubular SOFC stack. By arranging this, the raw fuel flows along the axis of the internal reformer to be moderately reformed and returns at the end of the internal reformer as a sufficiently reformed fuel. In this paper, the output characteristics of this configuration are simulat ed using mathematical models, in which one-dimensional temperature and mola r distributions are computed along the flow direction. By properly mounting the catalyst density in the internal reformer, the temperature distributio n of the cell stack becomes moderate, and the power generation efficiency a nd the exhaust gas temperature are higher. Effects of other operating condi tions such as fuel recirculation, fuel inlet temperature, air recirculation and air inlet temperature are also examined under the condition where the maximum temperature of the stack is kept at 1300 K by adjusting the air flo w rate. Under this condition, these operating conditions exert a considerab le effect on the exhaust temperature but have a slight effect on the effici ency. (C) 2001 Elsevier Science B.V. All rights reserved.