Experimental measurement and analysis of local current density of PEM fuel cells
| Autor: | Mei Sheng-Chin, 梅聖鑫 |
|---|---|
| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 This study examines the effects of angle of PEM fuel cell and operating parameters on cell performance of PEM fuel cells. The experimental methods include the measurement of overall cell performance and local current density with no-contracted magnetic technique. The transport phenomenon of fuel cell is detected by the measurement of the local current density distributions and pressure drop. The topics of this thesis include: (1) posing angle effects of fuel cell, (2) effects of operating parameters. The measured results show that best performance is noted for a 0 degree of posing angle. It is because that the better water management is found for the fuel cell with 0 degree of posing angle. Therefore, better cell performance is noticed. For operating parameter effects, two parts are investigated: (1) effects of steady-state loading, (2) effects of dynamic loading. For stead-state loading, a better cell performance is noted for a higher mass flow rate. But, the cell performance has a limit. Beyond a critical value of the flow rate, the flow rate on the cell performance is insignificant. Additionally, it is found that much more uniform local density distribution is noticed for the condition with lower cell temperature and operating loading. This is due to the lower water production on the cathode side. For the measurement of the pressure drops, the total and cathode pressure drops increase with an increase in the operating current density (loading) between 0.2-0.7A/cm2. For the dynamic loading, the response time would be delayed for a lower flow rate under higher operating loading conditions. In addition, the response time is shorter for a system with a higher cell temperature. But, too much higher cell temperature would cause a lower cell performance due to the non-uniform local current density distributions. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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