Design and numerical analysis of air-cooled proton exchange membrane fuel cell stack for performance optimization

Abstract

Proton exchange membrane fuel cell (PEMFC) is a promising electrical power source for the unmanned aerial vehicles (UAVs). In this paper, a novel kW-scale air-cooled PEMFC stack based on graphite plate is designed with 125 cm2 reaction area for the UAVs applications. The extra edge channels of air cooling are designed for enhanced performance and lowered weight of the stack. Meanwhile, for optimized power system integration of the stack, the counter-cross and co-cross operations are compared in terms of performance and thermal behaviors. Validated by the 5-cell short stack tests, a 3D multi-physical model is developed to investigate the uniformity of local performance and thermal behaviors under various operating conditions. The results suggest that the counter-cross operation has better performance than that of the co-cross with enhanced uniformity of reaction current and water content distributions. The multiple-island shaped electrolyte current distribution patterns are observed while the local water content and temperature distributions accord with the cathode flow field structure. The thermal convection of the extra edge channels could enhance the stack performance with lowered membrane dehydration and uniformity of the temperature distributions. The findings of this work are beneficial for optimization of the stack design with relevant operation strategy.