Large–scale DMFC stack model: The effect of a condensation front on stack performance

The cathode flooding has a significant impact on DMFC performance. Liquid water reduces diffusion of oxygen through the cathode GDL. Oxygen transport problems on the cathode side redistribute the rate of methanol consumption and eventually lead to transport limitations on the anode side. Our model shows that there is a critical level of flooding of the cathode backing layer below which the cell performance suffers greatly, eventually running the risk of cell reversal. This critical point is reached when the oxygen diffusivity in the flooded domain drops by a factor of five with respect to the normal non-flooded level.

► A Large-scale DMFC stack model is used to determine the effect of cathode flooding on stack performance.
► In each cell, flooded domain is modelled as the region with reduced oxygen diffusion coefficients in the cathode GDL.
► A critical level of flooding is found below which performance loss is severe.