Effect of channel materials and trapezoidal corner angles on emerging droplet behavior in Proton Exchange Membrane Fuel Cell gas channels

Ex situ experiments were conducted to study water droplet dynamics in Proton Exchange Membrane Fuel Cell (PEMFC) gas channels with different trapezoid channel open angles and GDL materials under controlled air velocities (0.48-7.23 m s−1). High speed videos revealed that the droplets interacted with the channel walls at lower air velocities (0.48-4 m s−1) and led to channel corner filling depending on the channel open angle. However, at higher air velocities (4.1-7.23 m s−1), the droplets did not contact the channel walls and slid off from the GDL surface. For higher air velocities, a correlation was obtained for the minimum velocity required to remove the droplet from the channel without interacting with the channel walls. For lower air velocities, the minimum pressure drop required for removing the droplet from the gas channel for both corner filling and non-filling scenarios was obtained. The study clearly establishes the important role played by the channel sidewalls and the channel angle on the water droplet transport characteristics.