Bidirectionally coupled multiphysics modeling of SOFCs: Start-up acceleration, wave-channel advantages, and dynamic responses

Based on a bidirectionally strongly coupled multiphysics transient model, this study investigated the dynamic characteristics and influencing factors of solid oxide fuel cells (SOFCs) during start-up stage. The effects and mechanisms of operating temperature, flow channel structure, and operational parameters on start-up duration, temperature distribution, current density, and fuel utilization were explored. Additionally, the dynamic impacts of fluctuations in voltage, temperature, and inlet flow velocity on operational stability were analyzed. Results showed that increasing the switching temperature (ST) from 473 K to 973 K reduced the SOFC start-up duration by 38.6%. Maximum temperature gradients were observed at the initial and final stages of start-up. Compared with straight channels, wavy channels prolonged the start-up duration by 23% but enhanced the steady-state current density by 17.5%, with only a 1.3% increase in average temperature. Fluctuations in operating temperature dominated the effects on current density, fuel utilization, and average temperature, while the impact of inlet flow velocity was negligible. Current density responded most rapidly to parameter fluctuations (600–1400 s), and average temperature responded the slowest (2300–2400 s). A 40% reduction in operating temperature led to a 98.4% plummet in current density and a 40.7% decrease in average temperature. This study provided theoretical and practical support for the development of rapid start-up strategies and optimized flow channel designs for SOFCs.