期刊
ELECTROCHIMICA ACTA
卷 256, 期 -, 页码 279-290出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.electacta.2017.10.012
关键词
porous media; fuel cells; phase-change-induced flow; evaporation; X-ray tomography
资金
- National Science Foundation under CBET [1605159]
- Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy [DE-AC02-05CH11231]
- DOE Office of Science [DE-AC02-06CH11357]
- Fuel Cell Performance and Durability Consortium (FC-PAD)
- Fuel Cell Technologies Office (FCTO), Office of Energy Efficiency and Renewable Energy (EERE), of the U.S. Department of Energy [DE-AC02-05CH11231]
- Div Of Chem, Bioeng, Env, & Transp Sys
- Directorate For Engineering [1605159] Funding Source: National Science Foundation
The performance of polymer-electrolyte fuel cells is heavily dependent on proper management of liquid water. One particular reason is that liquid water can collect in the gas diffusion layers (GDLs) blocking the reactant flow to the catalyst layer. This results in increased mass-transport losses. At higher temperatures, evaporation of water becomes a dominant water-removal mechanism and specifically phase-change-induced (PCI) flow is present due to thermal gradients. This study used synchrotron based micro X-ray computed tomography (CT) to visualize and quantify the water distribution within gas diffusion layers subject to a thermal gradient. Plotting saturation as a function of through-plane distance quantitatively shows water redistribution, where water evaporates at hotter locations and condenses in colder locations. The morphology of the GDLs on the micro-scale, as well as evaporating water clusters, are resolved, indicating that the GDL voids are slightly prolate, whereas water clusters are oblate. From the mean radii of water distributions and visual inspection, it is observed that larger water clusters evaporate faster than smaller ones. (C) 2017 Elsevier Ltd. All rights reserved.
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