| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 93 === The thesis consists of three parts. The first one is the simulation of 1-D model. The obtained results of oxygen distribution and cell polarization curve are compared with these of Gurua [13]. In the oxygen distribution, they are almost identical with the same application of three different porosities in GDL. On the other hand, with single value of porosity, 0.3 in GDL, the present study predicts a lower oxygen concentration. The polarization curve obtained from the present study is exactly the same as the one by Gurau [13]. The second part is the 2-D model. In this model, the distributions of oxygen, water, pressure and the cell polarization curves are compared with four different tapering ratios (100%, 75%, 50% and 25%). The results indicate that the cell performance is improved with a lower tapering ratio. The cell polarization curves in present 1-D model and 2-D model are compared each other, and it shows that the performance of 2-D model is lower than 1-D model due to the lower reaction of oxygen, resulting from one additional diffusion. The third one is the 3-D model. In this 3-D model, we also compare the distributions of oxygen, water, pressure and cell polarization curves with four different ratios. The results are similar to the ones in 2-D model and the cell performance is better with the lower ratio. Finally, we compare the cell polarization curves in present 2-D and 3-D models. The results show that the performance of 3-D model is lower than 2-D model with the same reason mentioned previously.
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