In Situ Imaging of Water Distribution in a Gas Diffusion Layer by Neutron Radiography

Abstract

In this study, neutron imaging was used to study water transport in a gas diffusion layer (GDL) during liquid water imbibition and drainage. It was shown that the liquid water saturation level in the GDL above the ribs was less than that above the channels, illustrating the role of the flow field elements on the local water distribution in the GDL. The difference in the liquid saturation level was attributed to the higher compression level of the GDL above the ribs leading to different morphological properties and, consequently, transport properties. Once liquid water breakthrough was reached, water was observed to flow through a single pathway. These results demonstrate that the assumption of isotropic transport properties of the GDLs in PEM fuel cell models needs to be reconsidered.