Figs. 13 and 14 show the mole fract

Figs. 13 and 14 show the mole fractions of the gas species O2, H2, and H2O at the interface GDL/channel. While xO2 clearly decreases in the direction of the gas flow due to its consumption, xH2 decreases close to the anode inlet and then slowly increases again. This can be explained as follows :towards the anode outlet, the water transport across the membrane rises (see Fig. 10) caused by the higher current density in this region (see Fig. 8 left) which enhances electro-osmosis. Consequently, the mole fraction of water vapor xH2O in theanode channel decreases leading to the increase of xH2 .As expected, in the cathode channel xH2O increases towards the outlet. Finally, Fig.15 shows the relative pressures for both flow channels.