Theoretical model and control-parameter classification analysis for solid oxide fuel cell systems with cooling air bypass into burner

The burner is central to the thermal management of solid oxide fuel cell (SOFC) system. Using cooling air bypass (CA) into burner is simple and effective to control the excessive temperature. A novel theoretical model for SOFC systems equipped with CA into burner is developed and verified with multiple experimental data. A comprehensive control-parameter classification analysis is carried out with the model, revealing quantitatively the impacts of the fuel utilization (Uf), air flow rate (Vair), and maximum burner temperature (TBM), on the system performance. The results confirm CA can minimize thermal shock to the stack. Favorable combinations of (Uf, Vair, TBM) satisfying the thermal constrains of maximum cell temperature and temperature difference are identified, and capable of achieving a system alternating current efficiency of 55 % or more. The theoretical model can help the system design optimization targeting the specifics of the stack.