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Julie E Steinbrenner, Carlos H Hidrovo, Fu-Min Wang, Sebastien Vigneron, Eon Soo Lee, Theresa A Kramer, Ching-Hsiang Cheng, John K Eaton, Kenneth E Goodson

Applied Thermal Engineering, Volume 27, Issue 10, July 2007, Pages 1722-1727

Abstract: Polymer electrolyte membrane (PEM) fuel cells incorporating microchannels (D < 500μm) can benefit from improved fuel delivery and convective cooling. However, this requires a better understanding of two-phase microchannel transport phenomena, particularly liquid–gas interactions and liquid clogging in cathode air-delivery channels. This paper develops optical fluorescence imaging of water films in hydrophilic channels with varying air velocity and water injection rate. 

Micromachined silicon test structures with optical access and distributed water injection simulate the cathode channels of a PEM fuel cell. Film thickness data vary strongly with air velocity and are consistent with stratified flow modeling. This work facilitates the study of regime transitions in two-phase microchannel flows and the effects of flow regimes on heat and mass transfer and axial pressure gradients.