Analysis of water transfers in micro fuel cells

The problem of water management is crucial in micro fuel cells. Structure and hydraulic characterization of the porous cathode has been carried out in that objective. Absorption (X-rays and neutrons) and SAXS experiments have been done in order to analyse water behaviour within the cell. The wettability of the fuel cell's surface has been modified with the goal of improving the performance. A hydrophobic deposit delays the flooding of the cell, whereas a hydrophilic deposit deteriorates the performance. A model of two phase and transient flow in the porous cathode, with the boundary conditions coupled with a droplet model has been developed and solved with Comsol. We were able to simulate the working tendencies of the cell, that is to say the notable influence of the intensity on the temperature elevation and the relative humidity and surface wettability on the flooding. (author)