Addition of non-reacting gases to the anode flow field of DMFCs leading to improved performance

Abstract

Contrary to conventional conceptions, we find that an external addition of non-reacting gases to the anode flow field of a direct methanol fuel cell led to improved cell performance. Our theoretical analysis shows that an increase in void fraction of the gas phase in flow channels reduces the cross sectional area of the liquid phase, thereby increasing the liquid velocity. The increased liquid velocity enhances the mass transfer of methanol from the flow channel to the gas diffusion layer and hence, improves cell performance. Following the same idea of accelerating the liquid velocity by reducing channel depth, we further demonstrate experimentally that thinning channel from 3.0 to 0.5 mm resulted in an increase in peak power density by 67.5%.