Effects of porosity and humidity on cell performance of PEM fuel cells

Autor: Chien-Yao Juan, 阮健堯
Rok vydání: 2008
Druh dokumentu: 學位論文 ; thesis
Popis: 96
The purpose of this study is to establish a three-dimensional computational model of the proton exchange membrane (PEM) fuel cell. The main objective is to investigate the phenomena of the electron/mass transfer inside a PEM fuel cell with 5 different flow field designs. Particular attention is focused on the effects of a porosity of gas diffusion layer and fuel humidity on the detailed transport phenomena in PEM fuel cells. It is expected to obtain the optimal conditions which would produce the best cell performance under different flow fields design, porosity and humidity. Compared the conventional flow field (serpentine flow field, parallel flow field and z-type flow field) with the interdigitated flow field (z-type interdigitated flow field and parallel interdigitated flow field), it is found that for the conventional flow field, the cell performance enhances by increasing the field channel number, corner numbers and length. Regarding to the interdigitated flow fields, with the baffle, the fuel is forced through the catalyst layer, which in turn, causes a strong chemical reaction. In addition, the liquid water is removed effectively. These make cell performance of the PEM fuel cell with interdigitated flow field better than that with conventional flow field. On the other hand, by changing the porosity of gas diffusion layer at both anode and cathode sides, it is observed that better cell performance is noted for the PEM fuel cell with larger porosity of gas diffusion layer. It is also found that for the PEM fuel cell with conventional flow field, the cell performance decreases with an increase in the fuel humidity. In the same situation, the PEM fuel cell with interdigitated flow field performs effectively than that with conventional flow field.
Databáze: Networked Digital Library of Theses & Dissertations
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