In-situ measurement of RH/T distribution in the straight-channel PEMFC under long-term operation with NEDC mode

This paper presents the development of an experimental system designed to evaluate the durability of a custom-designed single proton exchange membrane fuel cell (PEMFC) during extended operation, utilizing the New European Driving Cycle (NEDC). In particular, multiple micro-RH/T sensors are installed within the flow field plate channels to enable in-situ measurements of relative humidity and temperature (RH/T) distribution across the PEMFC flow field. Two case studies of 200 h durability test are conducted, incorporating shutdown recovery periods of 15 h and 45 h after every 50 h test block, to investigate the impact of shutdown duration on the PEMFC recovery. Comprehensive analyses focusing on temperature and water behavior demonstrate that the elevated risk of flooding is an unavoidable consequence of water accumulation during prolonged operation. This accumulation adversely affects reactant circulation and compromises the heat and water management capabilities of the PEMFC. Flooding can lead to several detrimental effects, including the membrane electrode assembly (MEA) structural deterioration, the formation of hotspots, and elevated cell temperature, ultimately resulting in accelerated performance degradation. Furthermore, this study highlights that water reduction within the PEMFC during shutdown recovery plays a critical role in enhancing water management and mitigating flooding. Notably, the shutdown recovery procedure restores approximately 60 % of performance losses after a 15 h shutdown. However, extended shutdown durations result in excessive water depletion, reducing recovery effectiveness to an average of 48 % after 45 h shutdown periods.