Experimental Study on the Droplet Transport and Dynamic Behavior in Flow Channel with Microprotrusions of PEMFC

Water management plays a crucial role in the performance of proton exchange membrane fuel cells (PEMFC). In this paper, to speed up the removal of water in the flow channel, the microprotrusions are fabricated on the flow channel surface by using laser remelting, and the surface is then sprayed with nanohydrophobic materials. The contact angle of the surface after spraying the hydrophobic material and laser processing increases from 115° to 132° when only the hydrophobic material is sprayed. Through visualization experiments, the movements of droplets in the smooth and microstructured flow channel are compared at different gas inlet pressures and different water inlet mass flows. The results show that the contact form of droplets with smooth surface is a solid-liquid contact, whereas there is also a liquid-gas contact with a microstructured surface. The main movement form of droplets in the smooth flow channel is sliding, whereas in the microstructured flow channel it is rolling. Under different experimental conditions, the movement speed of droplets in the microstructured flow channel is faster than that of the smooth flow channel, which indicates that the flow channel with microprotrusions has a better drag reduction performance. As the gas inlet pressure increases, the initial diameter of the droplet gradually decreased, and the velocity of the droplet increases. The water inlet mass flow has little effect on the oscillation amplitude of the droplets in the smooth flow channel, whereas in the microstructured flow channel, the droplet oscillation amplitude increases with the increase of the water inlet velocity. This work provides a new choice for the design of a flow channel.