A Slope Right-angle Turn Applied in the Flow Channel Promotes Water Management in Proton Exchange Membrane Fuel Cells

Effective water removal and transport in the flow field is significantly important to the critical water management in proton exchange membrane fuel cells (PEMFCs). In this work, a slope turn was proposed in the hydrophobic channel of the multi-serpentine flow field, and the transport and dynamics of water in the modified flow channel were numerically investigated with the volume-of-fluid method. The simulation results indicated that, with the presence of the slope turn, the water droplet can be effectively detached from the surface of the gas diffusion layer although the channel walls are hydrophobic. Meanwhile, the hydrophobic channel walls are beneficial to decrease interfacial resistance of water transport, avoiding water accumulation in the flow channel. The wall contact angle, slope angle and gas flow velocity are three important factors which significantly affect water behavior and pressure drop in the flow channel. For considered cases in this work, the appropriate wall contact angle, slope angle, and gas flow velocity were proved to be 140 degrees, 110 degrees, and higher than 2 m s(-1), respectively.