Probing the water content in polymer electrolyte fuel cells using neutron radiography

This work presents an in situ study on the water-content measurement in polymer electrolyte fuel cells (PEFCs) using neutron imaging. The effects of several important operating and design parameters on water content are examined, including the relative humidity (RH), the polytetraflouroethylene (PTFE) loadings in gas diffusion media including the microporous layer (MPL), current density, and flow field configurations including single-/quad-serpentine channels and co-/counter-flow configurations. Efforts are also made to distinguish water contents between the channel and land projected areas, and obtain the water profile along the gas flow path. We find that the highest water content occurs at a low current density for fixed operational stoichiometry, and liquid water emerges downstream at low humidity and increases rapidly after on-set.