کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1288668 | 973272 | 2011 | 12 صفحه PDF | دانلود رایگان |
A microfluidic device is employed to emulate water droplet emergence from a porous electrode and slug formation in the gas flow channel of a PEM fuel cell. Liquid water emerges from a 50 μm pore forming a droplet; the droplet grows to span the entire cross-section of a microchannel and transitions into a slug which detaches and is swept downstream. Droplet growth, slug formation, detachment, and motion are analyzed using high-speed video images and pressure–time traces. Slug volume is controlled primarily by channel geometry, interfacial forces, and gravity. As water slugs move downstream, they leave residual micro-droplets that act as nucleation sites for the next droplet-to-slug transition. Residual liquid in the form of micro-droplets results in a significant decrease in slug volume between the very first slug formed in an initially dry channel and the ultimate “steady-state” slug. A physics-based model is presented to predict slug volumes and pressure drops for slug detachment and motion.
► We study (ex situ) droplet/slug formation in gas channels of PEM fuel cells.
► Physical modeling successfully estimates slug volume/pressure drops.
► Gravity orientation affects slug formation; pendant droplets form smaller slugs.
► Residual micro-droplets/films alter surface wettability and slug formation/volume.
► Insights from experiments/modeling can enhance fuel cell flow design/operation.
Journal: Journal of Power Sources - Volume 196, Issue 23, 1 December 2011, Pages 10057–10068