| Summary: | 碩士 === 元智大學 === 機械工程學系 === 92 === The performance of PEM fuel cell under different operating conditions has been studied experimentally and numerically in the thesis. Five different types of flow channel, including spiral, traditional column, traditional serpentine, and two new serpentine types with different density of turns, have been experimentally investigated for different flow rates and orientations. The uniformity of fuels affects the mass transfer and the corresponding fuel cell performance. The results show that the performance reaches the optimum at the flow rate of 200 cc/min for all the flow types except for the spiral one and that the two new serpentine types with more turns have better performance than the others. It is also found that further increase of the flow rate does not improve the performance. As for the orientations, the original types show their best performance for the two new serpentine flow types; however, the performance of the traditional column type with 180 degree turn-around of the cathode is better than its other orientations; for the traditional serpentine type, the orientation does have any significant effect on the performance. In addition, the spiral flow type is specially appropriate for inlet conditions with no or low humidification due to its specific geometric configuration.
The numerical simulations provide further detailed information inside the fuel cell that can not be seen by experiments. The numerical results show the fuel concentrations, water vapor concentration, pressure and current density distributions and will help understand the physics and phenomena occurring in the fuel cell and can benefit the future studies of improvement.
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