Dynamic modeling of solid oxide fuel cell and engine hybrid system for distributed power generation

Novel hybrid system composed of solid oxide fuel cell (SOFC) and engine has been presented by our previous study. The fuel contents remained in the anode tail gas from the SOFC is reutilized in the engine to improve the system electrical efficiency. Our previous research has confirmed the electrical efficiency of the SOFC-engine hybrid system can be enhanced by about 7.8% compared to the SOFC stand-alone system. Although the hybrid system has higher electrical efficiency than the stand-alone system, higher elaboration for the system operation should be necessary due to higher degree of system complication. The objective of the present study is to develop the dynamic modeling of the SOFC-engine hybrid system. The component dynamic modeling of SOFC, engine, external reformer, air blower, and heat exchanger are developed and integrated into a system using Matlab-Simulinle (R). Component models of SOFC, external reformer, and engine have been verified by comparison with the experimental data. The dynamic behavior of the hybrid system during transients is investigated. Since the time scale for the engine operation is much shorter than that of the SOFC stack, the power generated by the engine is mainly dependent on the characteristics variation of the anode tail gas. Consequently, the overshoot behavior is appeared in the engine power generation during increase of the demand SOFC power. This model is useful to develop the optimal control strategy for the SOFC-engine hybrid system. (C) 2017 Published by Elsevier Ltd.