Investigation of consistency and uniformity for commercial-size proton-exchange membrane fuel cell stack based on multipoint impedance measurement

Résumé fourni par la source

Abstract The proton-exchange membrane fuel cell is a highly attractive clean energy technology for the future. However, differences in the consistency and uniformity of commercial-size fuel cell stacks significantly impact their health status and lifespan. This study is based on a commercial-size 10-cell stack. First, the characteristic frequency was determined by multipoint voltage and impedance sweeping experiments. Subsequently, the consistency and uniformity of the output characteristics of the stack at various loads under standard operating conditions were comprehensively analyzed using fixed-frequency multipoint impedance. Finally, a sensitivity analysis was conducted to quantitatively assess the effects of key parameters, including the air stoichiometry ratio and operating temperature, on the consistency and uniformity of voltage and high-frequency resistance. The inconsistency is more pronounced at high current densities, especially at the cathode inlet side compared to the outlet side. At low-current-density operation, the high-frequency resistance is greater at the cathode inlet side compared to the outlet side due to uneven gas distribution and more severe membrane drying at the inlet side. Increasing the air stoichiometry ratio enhances the consistency and uniformity of the stack. The effect of temperature on stack consistency is not significant in the appropriate temperature interval, but higher temperatures can reduce cell uniformity differences. The analytical approach in this study can provide guidance for stack consistency and uniformity studies.

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