Why a more uniform fuel/oxygen distribution is critical for fuel cell stack performance improvement

The effect of fuel/oxygen distribution uniformity on fuel cell performance is usually obtained from computational fluid dynamics (CFD) numerical simulations and is not well understood. In this technical note, a simple model is employed to provide easy understanding on why a more uniform fuel/oxygen distribution can enhance fuel cell performance at a given flow rate. Results show that the SOFC performance does not vary too much at a high H2 molar fraction but decreases significantly with decreasing fuel concentration at a low H2 molar fraction. With improved uniformity of fuel/oxygen at given flow rates, the performance improvement in the downstream exceeds the performance reduction in the upstream, leading to better fuel cell performance. The results are based on fuel distribution along the flow channel and can be applied to fuel distribution among different fuel cell units in a stack.