Electrochemical performance analysis of a commercial-scale planar solid oxide fuel cell stack and its sensitivity to operating parameters

Solid oxide fuel cell (SOFC) is a promising energy conversion technology for stationary applications due to its high efficiency, originating from the high operating temperature. It acts as a stable power supply with high space utilization when densely stacked, producing electrical output up to 1∼5 kW. Despite these advantages, it still faces the challenge of resolving thermal imbalance and nonuniform distribution of reaction zones within the stack. This study aims to elucidate the commercial-scale stack's electrochemical response to the key operating conditions including fuel utilization and operating current density, mainly focusing on the changes in the cell voltage trend, the current density distribution, and the temperature profile. Key indexes affecting the stack performance are defined, and their sensitivities are analyzed. A commercial-scale three-dimensional hydrogen-fueled SOFC stack is used as the physical model. The results show that, at high fuel utilization, the voltage loss occurs as heat generation increases, which is caused by reactant depletion. In-plane temperature and current density distribution also deteriorate. Increasing the operating current density has a relatively minor impact on the planar current density distribution while still increasing the in-plane temperature deviation. Integrating the abovementioned insights, effective methods to adjust the operating conditions are suggested.