Abstract
The process of flooding has been examined with a single-channel fuel cell that permits direct observation of liquid water motion and local current density. As product water flows through the largest pores in the hydrophobic GDL, drops detach from the surface, aggregate, and form slugs. Flooding in polymer electrolyte membrane (PEM) fuel cells occurs when liquid water slugs accumulate in the gas flow channel, inhibiting reactant transport. Because of the importance of gravity, we observe different characteristics with different orientations of the flow channels. Liquid water may fall away from the GDL and be pushed out with minimal effect on the local current density, accumulate on the GDL surface and cause local fluctuations, or become a pulsating flow of liquid slugs and cause periodic oscillations. We show that flooding in PEM fuel cells is gravity-dependent and the local current densities depend on dynamics of liquid slugs moving through the flow channels.
Original language | English (US) |
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Pages (from-to) | 1313-1332 |
Number of pages | 20 |
Journal | AIChE Journal |
Volume | 54 |
Issue number | 5 |
DOIs | |
State | Published - May 2008 |
All Science Journal Classification (ASJC) codes
- Biotechnology
- Environmental Engineering
- General Chemical Engineering
Keywords
- Fuel cells
- Multi-phase flow
- Porous media
- Transport