Improved water removal from fuel cell flow channels via natural frequency excitation of free surfaces
The accumulation of water drops and the subsequent formation of plugs in the reactant flow channels of proton exchange membrane (PEM) fuel cells can result in an uneven distribution of reactants leading to decreased performance and degradation. Small water drops, when excited at their natural frequency, will oscillate with little energy input. These drops can accumulate sufficient inertia, even at very small length scales, to overcome contact angle hysteresis, allowing the water drop to be expelled from the channel at low reactant flow rates. An ex-situ experiment designed to mimic a low-pressure drop reactant flow field was used to test this concept. The liquid surfaces were excited at their natural frequency using an acoustic pressure wave superimposed on the gas flow rate. The gas flow rate required to maintain water movement within one channel in parallel with unrestricted channels was significantly reduced when using this method. © 2011 ECS - The Electrochemical Society.
Improved water removal from fuel cell flow channels via natural frequency excitation of free surfaces.
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