Micro structured flow field for passive water management in miniaturized PEM fuel cells

In this work a novel flow field for the passive water management in proton exchange membrane fuel cells (PEMFC) is described. A triangular micro channel forces condensing water droplets to detach from the gas diffusion layer (GDL) in order to ensure proper oxygen supply. Water droplets are lifted into a secondary channel, and transported out of the fuel cell by capillary forces. Different droplet shapes inside the channels are identified. Preferred shapes cover the GDL only slightly and can be attained for contact angles typical for fuel cell materials. The new channel design was compared in a test fuel cell to standard square channels in particular in the starting phase of the cell at low working temperatures (22degC). The new channel design keeps the cell at 95% of its initial performance compared to 60% when using the standard design.