Abstract:

A bidirectional hydrogen supply strategy and an alternating hydrogen supply strategies were proposed to enhance the operational of air-cooled proton exchange membrane fuel cell (PEMFC) stacks. A combined methodology of numerical simulation and experimental calibration was employed to systematically investigate the distributions of hydrogen concentration and membrane water content within the PEMFC stacks, as well as the corresponding stack output characteristics under all different strategies. The results show that the bidirectional strategy achieves the highest uniformity of hydrogen distribution across the anode catalytic layer, with a maximum hydrogen mass fraction difference of 0.27, significantly lower than the 0.46 observed under the conventional unidirectional strategy. The alternating strategy yields the most uniform water distribution in the proton exchange membrane, markedly outperforming the unidirectional strategy. In the high current density regions, as the load current density increases, the differences in output voltage of the stack under the three strategies become progressively more pronounced; the alternating strategy delivers the superior electrochemical performance, followed closely by the bidirectional strategy. At a current density of 0.5 A/cm², the alternating strategy exhibits a maximum voltage fluctuation of 3.4 mV and a current density standard deviation of 140.2 mA/cm², while the bidirectional hydrogen supply strategy has 2.7 mV, and 136.1 mA/cm², respectively, demonstrating the improved voltage stability and the marginally better current distribution uniformity, thereby outperforming both the other strategies under high-load conditions. The experimental results validate the quantitative accuracy of the simulated performance trends for the bidirectional strategy, thereby confirming its technical feasibility and practical potential.

Key words: proton exchange membrane fuel cell (PEMFC) stacks, water management, water content, hydrogen supply strategy