Influence of droplets arrangement on an optically characterized GDL and correlation to water management

Proton Exchange Membrane (PEM) Fuel Cell (FC) presents itself as a promising technology in view of zero-tailpipe emission vehicles. In addition, the constant development of renewable energy sources will lead to an increase in green hydrogen availability, and thus completely eliminate emissions for devices that use H2 as an energy vector. However, PEM FCs are still far from being fully developed as a technology: thermal and water management are the main issues that researchers are studying through experiments and Computational Fluid Dynamics (CFD) simulations. For the numerical approach, H2O removal models often consider a simplified flat surface, but the microgeometry of the Gas Diffusion Layer (GDL) has a leading role in determining the critical dimension for droplet detachment and how much resistance the surface poses to water sliding.

The aim of this paper is to investigate the influence of droplets number on a GDL. The GDL has been characterized through optical analysis (5 μm/pixel spatial resolution) and the key features of the interlaced structure has been determined by using an approach typical of the textile industry. Droplet size (diameter ranging from 200 to 600 μm) and reciprocal distance have been parametrized and their behavior has been observed under the effect of 10 m/s cross airflow in a closed PEM FC channel layout. A different texture has been generated with the aim of evaluating the influence of the microstructure on water removal rates.