Performance investigation on the bypass ejector for a proton exchange membrane fuel cell system

• Published in: Applied thermal engineering Vol. 241; p. 122349
• Main Authors: Han, Jiquan, Besagni, Giorgio, Mereu, Riccardo, Inzoli, Fabio, Feng, Jianmei, Peng, Xueyuan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.03.2024
• Subjects: Computational fluid dynamics; Ejector; Hydrogen recirculation; Proton exchange membrane fuel cell; Hydrogen recirculation; Ejector; Proton exchange membrane fuel cell; Computational fluid dynamics
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2024.122349

[Display omitted] •The bypass ejector exhibits a notable performance improvement at critical mode.•The optimal position and width of bypass inlet increase as stack power increases.•The hydrogen entrainment ratio increases by 22.1 % for bypass ejector at 101 kW.•Backflow occurs at the bypass inlet when operating below 24 kW. The poor entrainment performance of the conventional ejector is a significant problem that makes it hard to use in proton exchange membrane fuel cell (PEMFC) systems. This study aims to evaluate the entrainment performance of a bypass ejector for a 100 kW PEMFC system. The effects of three critical geometric parameters, namely the axial position, width, and angle of the bypass inlet, on the entrainment performance are thoroughly investigated. The results demonstrate that the bypass flow exhibits a significant performance improvement in the critical mode. In contrast, the performance improvement is negligible and even negative in the subcritical mode. After careful evaluation of the entrainment performance across various stack powers, the optimal axial position, width, and angle of the bypass inlet are found to be 1.1, 2 mm, and 10°, respectively. A comparative analysis between the bypass ejector and the conventional ejector underscores a significant advantage for the former, exhibiting a remarkable 22.1 % increase in the hydrogen entrainment ratio at the stack power of 101 kW. Nevertheless, the entrainment performance of the bypass ejector diminishes when operating at low stack powers below 24 kW.