Dynamic modeling and experimental validation for the electrical coupling in a 5-cell solid oxide fuel cell stack in the perspective of thermal coupling

The electrical coupling in a 5-cell solid oxide fuel cell (SOFC) stack is investigated in this research. The electrical characteristics tests of a single cell and the stack were performed in an electrical furnace. It was found that the single cell with the highest temperature does not give the highest output voltage in the stack test, which is different from the result that the output voltage increases with temperature in the single cell test. A physical interpretation for this phenomenon is given specifically from the standpoint of electrical coupling on the basis of thermal coupling between cells in the stack. Furthermore, a system level electrical coupling dynamic model is developed to characterize the electrical characteristics of the stack by considering the contact resistance between cells. In addition, the electrical coupling dynamic model is calibrated and validated based on the experimental data. The results demonstrate that the electrical coupling dynamic model can depict and predict accurately the electrical characteristics of SOFC stacks. The accurate electrical coupling dynamic model is important for the system level study of SOFCs, such as the optimization of stack structures and the design of peripheral control systems.