Characteristics of heat, power generation, and energy efficiency study on a novel air-cooled PEMFC stack based on micro heat pipe arrays

This study introduces a novel kilowatt-scale air-cooled proton exchange membrane fuel cell stack utilizing micro heat pipe arrays (MHPA-PEMFC stack). This innovative stack design addresses issues commonly associated with conventional air-cooled fuel cell stacks, such as low heat transfer efficiency, suboptimal performance, and safety concerns, especially during high-load operations. In addition to the output performance of the stack, this study investigates the heat and power generation performance limits, operational security, and energy utilization efficiency of the MHPA-PEMFC stack under high power output and varying flow rates. The study introduces two novel evaluation indexes, namely, relative load gain (RLG) and relative safety gain (RSG), to provide a comprehensive evaluation. These indexes are utilized to link energy efficiency and exergy efficiency to the performance of the MHPA-PEMFC stack. The results show that the MHPA-PEMFC stack exhibits superior heat dissipation performance, uniform temperature distribution, and enhanced load capacity and safety compared with conventional PEMFC stacks. The maximum RLG and RSG achieved by the MHPA-PEMFC stack are 100% and 7.53, respectively. The energy efficiency of the MHPA-PEMFC stack surpasses 29% while maintaining a guaranteed maximum RLG. Notably, a higher RSG leads to a sacrifice in both energy and exergy efficiency.