SOFC stack reliability and efficiency study under load transitions based on minimum temperature deviation strategy

The requests for adapting to frequency load transitions of solid oxide fuel cell (SOFC) are brought forward due to variable power demand in application. Operating reliability and efficiency should be considered simultaneously to improve the stack performance throughout dynamic operation. A temperature management strategy, termed Minimum Temperature Deviation Strategy (MTDS), is proposed to optimize dynamical operating point selection during load transitions. The strategy accounts for the complex temperature distribution along the cell length, facilitating more rational temperature management and enhanced efficiency optimization for SOFC. A 2D model with multiphysical fields is developed to simulate steady and dynamic performances of a kW-class stack under load transitions. Comparative analysis between the proposed strategy and conventional operating strategies under 20% load-decreasing conditions demonstrates that the MTDS achieves competitive performance, enabling smooth internal state transitions, stable power output, and consistent exhaust fuel concentration while maintaining a relatively short transient duration. The results show merely 0.57% voltage overshoot, a maximum temperature reduction of 30.23 °C, and a transition time of 36.6 min. Subsequently, transition amplitude investigations based on the MTDS are conducted, which exhibit that the stack can maintain high efficiency and stable operation throughout a wide power variation range. Additionally, load-increasing conditions are particularly prone to overshoot in operating voltage and temperature, which can be effectively mitigated through slowing the load ramp or increasing the inflow flux ramp rate within appropriate ranges. Studies on comprehensive management and control strategies for the SOFC in system integration could be inspired based on the proposed strategy.