In this work, a 3D model of a PEM fuel cell has been developed for water saturation and its effects using a validated approach considering the internal movement of water across the membrane. For different operating levels, it was found that at lower current densities, the maximum saturation occurs faraway region from the air inlet because of the decrease in ability of air to evaporate the liquid water, while at higher current densities, a shift in the maximum value is noticed towards the inlet region due to increase in electro-chemical reaction rate and the electro-osmotic drag.
Apart from water saturation shift at different load conditions, it is also observed that the liquid water tends to accumulate at the interface of the inlet channel and the porous media. Considering the movement of water across the membrane, a linear profile for back diffusion was observed with increasing current density because of higher water content at the cathode. For the electro-osmotic drag, the increase is observed to follow the rate of increase of the electro-chemical reactions and becomes approximately constant at higher current density due to the concentration losses where the electro-chemical reaction rate is limited due to the physical characteristics
of the agglomerates. Although the rise trend of the back diffusion and
electro-osmotic drag followed a dissimilar pattern, the net transport was calculated
to be towards the anode side suggesting that the water content at the cathode side
increases with increasing current density, hence causing more problems for the PEM
fuel cells in terms of water management.
|Konferens||6th International Green Energy Conference (IGEC-VI)|
|Period||2011/06/02 → …|