Transient performance analysis of a solid oxide fuel cell during power regulations with different control strategies based on a 3D dynamic model

Solid oxide fuel cell (SOFC) is a promising power technology, which has the attributes of clean, high efficiency, and high flexibility. In this research, a 3D-dynamic model of a planar SOFC was established and experimentally verified. Based on the developed model, the dynamic response characteristics of SOFC are investigated after every step change in the inlet gas temperature, inlet gas flow, and output voltage. For the output voltage of 0.9V, 0.7V, and 0.6V, the power density varies by +13.6%/-16.7%, +11.0%/-15.3%, and +5.1%/-9.7%, respectively, against every increase/decrease the inlet gas temperature by 100 K. The response processes of the power density to the changes in both inlet gas flow and output voltage are divided into fast-response and slow-response stages. The power density changes in these two stages can be attributed to the change in reactant concentration within the functional layers (fast-response stage) and the slow evolution of cell temperature (slow-response stage), respectively. Subsequently, four control strategies are employed to increase/decrease the power density by 20%. The comparative results show that the integrated control strategy of changing multiple operating parameters simultaneously can reduce the change range of a single controlled parameter, thereby improving the power regulating capability and increasing the regulating speed.