Enhanced water removal performance of a slope turn in the serpentine flow channel for proton exchange membrane fuel cells.

Graphical abstract Highlights • Slope turn in hydrophobic channel can enhance water removal from MEA surface. • Slope turn should has the same sectional area as the straight channel. • Optimized slope angle is dependent on water behavior and pressure drop. • Large wall contact angle can accelerate water transport. Abstract Aim to effectively improve the removal and transport of liquid water in the flow channel in a proton exchange membrane fuel cell (PEMFC), we designed a slope turn in the serpentine flow channel and conducted numerical simulations using volume-of-fluid method to investigate the water behavior in it. To optimize the slope turn, the effects of the sectional area and slope angle of the slope turn and the wettability of channel wall on the transport and dynamics of water were investigated. Besides, cases with different sizes of single water droplet and the interactions between multiple droplets were also considered. For single droplet, the results suggest that with the designed slope turn, water droplet can be effectively removed from the surface of membrane electrode assembly (MEA) though the channel walls are hydrophobic. Without slope turn, the water droplet is transported downstream, always being attached on the MEA surface. The designed slope turn is also applicable for the case of multiple droplets to enhance water removal from the MEA surface. [ABSTRACT FROM AUTHOR]