Mass Transport Measurements in Porous Transport Layers of a PEM Fuel Cell

Abstract

Porous transport layers are an integral part of polymer electrolyte fuel cells (PEMFC). In order to optimize the catalyst layer performance and reduce catalyst consumption, a thorough understanding of mass transport through porous media is necessary. Currently, there is a lack of experimental measurements of effective mass transport properties of porous transport layers. Further, mass transport theories in the literature, such as the binary friction model by Kerkhof [1], have not been extensively validated for porous media. In the present study, mass transport measurements have been performed on the porous media of a PEMFC, namely a GDL and an MPL. The experimental setup described by Pant et al. [2] has been used. The setup uses the diffusion bridge/counter-diffusion technique for the mass transport measurements. The experimental setup has the advantage that it can be used to perform studies for pure diffusion and convection-diffusion mass transport. The setup also facilitates measurement of permeability of porous media, which can then be used in convection-diffusion studies. Preliminary permeability measurements of GDL and MPL from the setup show good agreement with values available in literature. In preliminary experimentation, the conventional diffusivity correlations like Bruggeman equation have been found to overpredict the diffusivities.