Visualization of liquid water in a lung-inspired flow-field based polymer electrolyte membrane fuel cell via neutron radiography

Lung-inspired, fractal flow-fields hold great potential in improving the performance of polymer electrolyte membrane fuel cells (PEMFCs) by providing uniform gas distribution across the electrodes and ensuring minimum entropy production in the whole system. However, the inherent susceptibility of th...

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Bibliographic Details
Published in:Energy (Oxford) 2019-03, Vol.170, p.14-21
Main Authors: Cho, J.I.S., Neville, T.P., Trogadas, P., Meyer, Q., Wu, Yunsong, Ziesche, R., Boillat, P., Cochet, M., Manzi-Orezzoli, V., Shearing, P., Brett, D.J.L., Coppens, M.-O.
Format: Article
Language:English
Subjects:
Capillary pressure
Channels
Diffusion layers
Electrolytes
Electrolytic cells
Entropy
Flooding
Flow
Fractal flow-field
Fractals
Fuel cells
Fuel technology
Gaseous diffusion
Hydrophobicity
Lung-inspired flow-field
Lungs
Neutron imaging
Neutron radiography
Outlet channels
Performance degradation
Polymers
Proton exchange membrane fuel cells
Radiography
Serpentine
Water
Water depth
Water management
Water treatment
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Summary:Lung-inspired, fractal flow-fields hold great potential in improving the performance of polymer electrolyte membrane fuel cells (PEMFCs) by providing uniform gas distribution across the electrodes and ensuring minimum entropy production in the whole system. However, the inherent susceptibility of the fractal flow-fields to flooding renders their use inadequate at high humidity conditions. In-depth understanding of water management in lung-inspired flow-fields is indispensable for the implementation of alternative outlet channel geometries or engineered water removal strategies to alleviate flooding. Here, liquid water formation and transport across the lung-inspired and serpentine flow-field based PEMFCs are evaluated using neutron radiography. The results reveal a propensity to flooding in the interdigitated outlet channels of the fractal flow-field with N = 4 generations as a result of slow gas velocity and narrow channel dimensions, which leads to significant performance deterioration. Neutron images also elucidate the importance of ensuring a well-defined internal channel structure of the fractal flow-fields to prevent backflow of liquid water via wicking and capillary pressure build-up arising from the narrow inlet gas channels and hydrophobic gas diffusion layer. •Neutron radiographs are presented for the lung-inspired and serpentine flow-fields.•A well-defined channel structure of the fractal flow-field is indispensable.•Water removal strategies required to alleviate flooding in the fractal flow-field.
ISSN:0360-5442
1873-6785
DOI:10.1016/j.energy.2018.12.143