| Summary: | 碩士 === 國防大學中正理工學院 === 兵器系統工程研究所 === 95 === Fuel cell is one kind of device which can direct convert chemical energy into electrical power by chemical reaction. The characteristics of fuel cell are low emission and high efficiency. The major advantages of Proton Exchange Membrane Fuel Cell (PEMFC) are applications of lower-temperature operation, quick starting stage, high energy density, long-life operation and simple structure design. Therefore, the PEMFC is regarded as one of the potential candidates in applications of portable power units.
The effects of channel structure of bipolar plate, operation temperature, and relative humidity of cathode gas on the performance of PEMFC are systematically investigated with CFD method. The single fuel cell unit with size of 5cm5cm is tested in present work. Three difference structure designs of parallel-channel, serpentine-channel, and interdigitate-channel of bipolar plates are evaluated and compared with the same fuel supply rate. The tested operation temperature is ranged from 323K to 353K. The relative humidity of anode fuel gas is fixed at 50%, while cathode O2 gas is varied as 50%, 75%, and 100%.
Present results show that the performance of fuel cell is strong relative to the structure of flow paths of bipolar plate at the same operational conditions. Among the tested flow structures, the serpentine-channel has the best performance while the pressure drop is also the highest. This is due to both the convective and diffusion transport phenomena of reaction gases occur within layers of diffusion and catalyst for anode and cathode sections. An enhancement in the performance of PEMFC observed regardless of the bipolar plate flow structures when the operation temperature is increases. The influence of relative humidity of cathode gas on the performance of PEMFC is not apparent at condition of 323K. When the operational temperature is heated up to 353K, it is observed that PEMFC performance increases with decreasing of the relative humidity of cathode gas from 100% to 50%.
|
|---|
