Modeling analysis of flow field geometrical features in polymer electrolyte fuel cells porous media

The present work gets insights into the mass transport phenomena taking place in hydrogen PEMFC with a modelling analysis based on computational fluid dynamics to interpret experimental data. Experimental polarization curves and electrochemical impedance spectroscopy (EIS) have been performed on membrane electrode assembly in H2/O2 and H2/Air configurations. PEMFC models (2D and 3D) have been considered and ad hoc simulations have been carried out to investigate the effects of geometrical features present in real flow fields: oxygen depletion under current collector, flow mixing in channel bends, flow bypass between adjacent channels. In addition to polarization curves, impedance spectra are simulated: local spectra are simulated along a 3D channel showing a low frequency feature that appears progressively moving along the channel in consequence of oxygen depletion on active sites. This feature is adopted to assess the effect of mass transport in PEMFC and discuss the effect of channel bends and rib/channel.