Improved Modeling and Understanding of Diffusion-Media Wettability on Polymer-Electrolyte-Fuel-Cell Performance [electronic resource]

• Ngôn ngữ: eng
• Ký hiệu phân loại: 680.2 Manufacture of products for specific uses
• Thông tin xuất bản: Berkeley, Calif. : Oak Ridge, Tenn. : Lawrence Berkeley National Laboratory ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2010
• Mô tả vật lý: Size: 56 : , digital, PDF file.
• Bộ sưu tập: Metadata
• ID: 257015
• Chủ đề: 1. 08 hydrogen; 2. 30 direct energy conversion; 3. 42 engineering; 4. 97 mathematics and computing; 5. Diffusion media; 6. Modeling; 7. Multiphase flow; 8. Pefcs; 9. Water management

Tóm tắt

A macroscopic-modeling methodology to account for the chemical and structural properties of fuel-cell diffusion media is developed. A previous model is updated to include for the first time the use of experimentally measured capillary pressure -- saturation relationships through the introduction of a Gaussian contact-angle distribution into the property equations. The updated model is used to simulate various limiting-case scenarios of water and gas transport in fuel-cell diffusion media. Analysis of these results demonstrate that interfacial conditions are more important than bulk transport in these layers, where the associated mass-transfer resistance is the result of higher capillary pressures at the boundaries and the steepness of the capillary pressure -- saturation relationship. The model is also used to examine the impact of a microporous layer, showing that it dominates the response of the overall diffusion medium. In addition, its primary mass-transfer-related effect is suggested to be limiting the water-injection sites into the more porous gas-diffusion layer.