Measurement and modeling of liquid film thickness evolution in stratified two-phase microchannel flows

• Published in: Applied thermal engineering Vol. 27; no. 10; pp. 1722 - 1727
• Main Authors: Steinbrenner, Julie E., Hidrovo, Carlos H., Wang, Fu-Min, Vigneron, Sebastien, Lee, Eon Soo, Kramer, Theresa A., Cheng, Ching-Hsiang, Eaton, John K., Goodson, Kenneth E.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2007; Elsevier
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Equipments for energy generation and conversion: thermal, electrical, mechanical energy, etc; Exact sciences and technology; Fluorescent imaging; Fuel cells; Liquid film; Microchannel; Stratified flow; Two-phase; Liquid film; Two-phase; Microchannel; Stratified flow; Fluorescent imaging; Measurement; Cooling; Cathode; Fluorescence; Modeling; Thickness; Water injection; Membrane; Silicon; Fuel cell
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2006.07.020

Polymer electrolyte membrane (PEM) fuel cells incorporating microchannels ( D < 500 μm) 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.