Characterisation of the diffusion properties of metal foam hybrid flow-fields for fuel cells using optical flow visualisation and X-ray computed tomography

Results using dyed water show that metallic foams provide excellent fluid distribution across the fuel cell flow-field, closely following the theoretical filling rate. The time for dye to cover 80% of the flow-field area was 61% faster with a foam flow-field then with no flow-field present. Pressure drop was seen to reduce with increasing foam inlet area to levels comparable to multi-serpentine flow-fields. The introduction of flow channels in the foam can further reduce pressure drop and provide more even filling of the foam, at the expense of increased residence time.