Abstract
This study observes the water removal process for the cathode-side of a DMFC. During the operation of a DMFC, a large amount of water vapor appears on the surface of GDL and partially condenses into water droplets. Excessive water at the cathode can cause flooding, which hinders oxygen access to the reaction sites and leads to reduced cell performance. To prevent flooding, the flow flied plate adopted capillary parallel channels with their rear ends attached with capillary metal wire mesh for water collection. Assisted by air convection and gravity force, the capillary force pumped out the condensed water effectively. For visualization, through parallel channels with cross-sectional dimensions of 500*1000μm were fabricated on the stainless-steel bipolar plate (BP). The surface of flow field plate was coated with gold to further increase the electrical conductivity and hydrophilicity. Through a hydrophilic glass plate covering the BP, the process of water condensation and subsequent removal can be observed. When the air flow rate was 80ml/min (stoichimetric ratios, λ=4), the power output reaches 15 mW/cm2, with the channels free from clogging.