Experimental analysis of water transport in the diffusion layer of a PEM fuel cell

Optimization of water management in Polymer Electrolyte Fuel Cells (PEMFC) is a very important factor for the achievement of high performances. A good hydration of the electrolyte membrane is essential for correct operation in order to avoid flooding at electrodes causing severe reduction in performances. Many studies on water transport across the gas diffusion layer (GDL) have been carried out to improve these components; anyway efforts in this field are affected by the lack of an effective and shared experimental method. The present work reports an experimental investigation with the purpose to determine the global coefficient of water transport across a GDL under real operating conditions. An appropriate experimental apparatus has been built to test the single GDL under a wide range of operating conditions. Experiments have been realized by feeding on both GDL sides a humidified air flow and a dry air flow respectively and measuring the quantity of water that crosses the GDL. Both temperature and relative humidity of air fluxes as well as distributors geometries are typical of real applications. Flooding onset has been observed and a simple characterization is presented.