Mass transport analysis of micro direct methanol fuel cell anode

A mathematical model for a micro direct methanol fuel cell (μDMFC) anode was presented. In particular, the flow channels of the anode were simplified as regular porous media. The theoretical model of anode regions including flow channels was established based on the theory of porous media. In addition to the mass transport in the catalyst layer, the model considered methanol crossover caused by diffusion and electro-osmosis. The distribution of liquid saturation and the effect of anode flow rate on current density were investigated. The methanol concentration distribution in the anode was also calculated. Moreover, the characteristics of mass transport in the anode were analyzed. It was found that the methanol concentration decreased along the anode flow channels, and reduced evidently along the direction perpendicular to flow channels with an increase in overpotential. Methanol concentration distribution in the anode diffusion layer and catalyst layer showed similar variations. The methanol crossover flux decreased along the direction parallel to flow channels. A higher current density led to a lower methanol crossover flux.