| Polymer electrolyte membrane fuel cells (PEMFCs) are attractive power sources due to their high efficiency, low temperature, low noise, and low pollution. However, proper liquid water management within an operating PEMFC stack is one of the limiting factors for achieving high power density. Gas diffusion layers (GDLs) play a critical role in the efficient transport of liquid water away from the catalyst layer at the onset of flooding. Understanding the role GDL morphology and wetting properties on the liquid water distribution can lead to better design and processing for improvements in liquid water management.;The work presented describes the development of a new tool and method for dynamic characterization of partially saturated porous media termed hydraulic admittance. Hydraulic admittance measurements were performed on increasingly more complicated porous media: single capillary, bundle of capillaries, an engineered sample, and GDLs. Hydraulic admittance is shown to be a sensitive characterization tool that can probe the unique hydraulic properties of pores with multiple free-interfaces. The results presented here serve as a foundation for further development of this method to understand the liquid water distribution of water in GDLs. |
