Spatiotemporal evolution of SOFC multiphysics under system operating constraints

The dynamic safety performance of solid oxide fuel cell-combined heat and power (SOFC-CHP) systems are pivotal for practical deployment. A cross-scale system-level dynamic model with bidirectional real-time coupling between macroscopic system components and 3D multi-physics SOFC model is developed in this work. A three-stage dynamic evolution pattern under typical variation modes: transient mutation (Stage I), gas diffusion-dominated recovery (Stage II), and heat transfer-dominated stabilization (Stage III). Stage I induces a current overshoot that is highly prone to local fuel starvation inside SOFC. In particular, the overshoots of the operating voltage and fuel flow modes reach 66.59% and 21.51%, with the local fuel concentration near outlet approaching zero. In Stage II, the current density evolves synchronously with the anode hydrogen concentration. The stabilization time of Stage III is on the order of hundreds to thousands of seconds. The exhaust gas heat from the afterburner and the electrochemical reaction heat jointly dominate the SOFC thermal properties. Flow variation modes feature a long stabilization time. Reducing the inlet hydrogen concentration improves the spatial uniformity of current density but exacerbates the temperature gradient inside the SOFC. The thermo-electric performance is extremely sensitive to fluctuations in power demand and inlet hydrogen purity.