Reagents in a PEMFC in Operation, Part I: Dry Gases.

Several mass transport phenomena develop during the operation of a PEMFC, each one of this generates a mechanical- physics resistance to some extent, implying limitations during operation. In a conventional fuel cell, the feeding reactive gases to the sites of reaction are performed by a series of elements such as: channels in the polar plates, diffusion layer on the electrodes and the active layer where it realizes the electrochemical semi reaction. Several studies reported show the generation of gradients of concentration in reagents between the channels of distribution and diffusion layer, representing a limiting in the transport of reagents to the active sites. Additionally, at high values of current density, the resistance to the mass transport of reagents is increased by the presence of water-product in the pores of electrodes, reducing significantly the performance of the PEMFC, including the complete cessation of its operation for flood. In consequent, this work focuses on reducing the resistance to mass transport by applying a rigid gas diffusion media with high number of macropores as distributor of reagents with the purpose to encourage the mass transport phenomena to the active sites on the electrodes. This gas distributor is manufactured using a commercial material, mixing carbon and graphite powders. The results show significant effects on the zone of diffusion in the PEMFC polarization curves, it is possible to reduce the mass transport limitations at high curren