Experimental study on the operating state of high-power vehicular fuel cell system hydrogen supply subsystem with an in-situ ultrasonic-based gas component monitoring equipment

High-power fuel cell systems represent a critical pathway toward large-scale hydrogen technology commercialization. These systems feature high-power stacks with larger active areas and more cells, which exacerbate issues such as local fuel starvation and voltage consistency deterioration, caused by nitrogen accumulation at the anode, flooding, and uneven gas flow distribution. While existing experimental studies on anode management have focused on low-power stacks, there remains a distinct lack of rapid, sensitive in-situ monitoring methods for internal state assessment of anode. To address these gaps, this paper introduces a novel ultrasonic-based sensor designed to monitor the concentration and flow rate of mixed gases simultaneously in the anode of the fuel cell system. Detailed observations and analyses were conducted on the variations in gas mixture concentration and flow rates within a 130 kW fuel cell system's hydrogen supply subsystem, examining their impacts on system output stability, hydrogen utilization rate, and energy conversion efficiency under various operational settings. The results reveal that increasing the nitrogen concentration from 1 % to 49 % has a minimal effect on the overall stack performance, as the average voltage decreases by only 1.53 %. However, the voltage fluctuation rate increases by 260 %, indicating a significant deterioration in voltage consistency. The voltage fluctuation rate proves to be an effective indicator for purge management in high-power systems. This study uniquely identifies a functional relationship between voltage fluctuation rate and hydrogen stoichiometric ratio. These insights will significantly contribute to advancing anode management strategies for high-power fuel cell systems in the future.