Analysis of an ethanol-fuelled solid oxide fuel cell system using partial anode exhaust gas recirculation

Abstract

This paper presents an analysis of a solid oxide fuel cell (SOFC) system integrated with an ethanol reforming process. The recycling of the anode exhaust gas in the integrated SOFC system is considered to improve its performance. The results indicate that under the same operating conditions, the SOFC system operated with the recycle of the anode exhaust gas has higher electrical and thermal efficiencies than a non-recycling SOFC system. The required conditions to prevent carbon formation in the ethanol reformer are also examined. When the SOFC system with anode exhaust gas recycling is operated at a higher recirculation ratio and fuel utilization, the carbon formation can be reduced, which in turn decreases the reformer operating temperature. However, the recirculation ratio has to be carefully selected because an increase in the recirculation ratio has an adverse impact on the electrical efficiency of the SOFC system. In addition, the results show that the electrical efficiency depends on the fuel utilization of the SOFC. At low fuel utilization (0.5–0.6), the electrical efficiency increases as the recirculation ratio increases. In contrast, when the SOFC is operated at a higher fuel utilization (>0.6), an increase in the recirculation ratio results in a decrease in the electrical efficiency.