Optimal design of a novel nested-nozzle ejector for PEMFC's hydrogen supply and recirculation system

The ejector-based hydrogen supply and recirculation system (HSRS) for a Proton Exchange Membrane Fuel Cell (PEMFC) system has the advantages of compact size and zero power consumption, compared with the HSRS using a recirculation pump. However, the conventional ejector with a single venturi nozzle c...

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Bibliographic Details
Published in:International journal of hydrogen energy 2023-08, Vol.48 (70), p.27330-27343
Main Authors: Chen, Li, Xu, Keda, Yang, Zuyong, Yan, Zhen, Zhai, Chengliang, Dong, Zuomin
Format: Article
Language:English
Subjects:
CFD simulation
Design optimization
Hydrogen supply and recirculation
Nested-nozzle ejector
PEMFC
Testing
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Summary:The ejector-based hydrogen supply and recirculation system (HSRS) for a Proton Exchange Membrane Fuel Cell (PEMFC) system has the advantages of compact size and zero power consumption, compared with the HSRS using a recirculation pump. However, the conventional ejector with a single venturi nozzle can only function within a narrow power range of the PEMFC system due to its restricted primary inlet pressure. This study proposed a novel ejector design with nested nozzles to solve this problem. The key geometric parameters, including the nozzle diameters of a large nozzle (BN), a small nozzle (SN), and the axial distance between two nozzles, were optimized using CFD simulations to obtain the maximum entrainment capability. The BN mode is responsible for the stack's higher load operations, while the SN mode supports the lower power operations. Additionally, a bypass was used parallel to the nested-nozzle ejector in the HSRS to extend the ejector operating range further. The consistent CFD simulation and testing results of the nested-nozzle ejector showed effective hydrogen entrainment capability between 9% and 100% of power output for a 150 kW PEMFC stack. Moreover, the new nested-nozzle ejector HSRS showed much-reduced anode inlet pressure fluctuation compared to the HSRS using two conventional ejectors. •Optimal design and testing of a nested-nozzle PEMFC hydrogen ejector.•Optimization of seven key geometric parameters using CFD simulations.•Incorporated a bypass in HSRS to extend ejector operating range.•Investigation of PEMFC anode pressure fluctuation of alternative HSRS.
ISSN:0360-3199
1879-3487
DOI:10.1016/j.ijhydene.2023.03.403