Computational Study of Flow Reversal for Improved Thermal Management in a PEMFC Stack With Forced Air Convection Cooling

In a proton exchange membrane fuel cell (PEMFC) stack equipped with a forced-convection open-cathode manifold, significant temperature gradients can develop from the inlet to the outlet due to the incoming cool air heating up as it passes through the cathode flow fields. In order to reduce these gradients, we consider flow-reversal of the air by reversing the flow direction of the fans that are providing the forced convection: This allows cool air to alternately enter the stack from the front and the rear instead of only from the front. The impact of the flow-reversal is studied with a model considering two-phase flow and conservation of mass, species, momentum, charge, and energy in the PEMFC stack and ambient; the fans are treated as interface conditions. The results indicate that the temperature, water and current density distributions become more uniform with an overall reduction of the maximum temperature in the stack.