Effects of Contact Angle Variation of the Gas Flow Channel Walls on Liquid Water Removal in PEMFC

Three-dimensional two-phase flow simulations have been performed by employing the volume of fluid (VOF) method to examine the effects of contact angle of gas flow channel walls on the droplet dynamics in the serpentine flow channel of PEMFC. Liquid water is injected from four adjacent pores on the bottom gas diffusion layer (GDL) surface. The droplets grow and they are detached and finally discharged due to gas flow in the channel. The influences of the channel wall contact angle on liquid water dynamics have been examined quantitatively for liquid water saturation and its coverage on the GDL surface. The present numerical results reveal that spatial variation of channel wall hydrophobicity can effectively control the liquid water removal in the gas flow channel. The spatiotemporal evolutions of liquid water droplets in the gas flow channels show that the hybrid case is most effective since the hydrophobic wall at the turning part reduces the water saturation in the channel and the hydrophilic wall at the straight part prevents the liquid water from covering the GDL surface.