| Summary: | 碩士 === 國立臺灣大學 === 應用力學研究所 === 92 === The principle concern of this study is about the oxygen transport situation in the cathode side of PEM fuel cells. A steady state and isothermal half-cell model is considered in the present study. It is assume that the oxygen concentration in the gas channel changes in the channel direction. While in the gas diffuser layer, the oxygen concentration varies across the membrane in the membrane direction. We successfully obtain an analytical solution that describe the phenomenon relate to oxygen transport and membrane phase potential. This solution can be used to analyze fuel cell performance with variable operating parameter.
It shows that increasing the porosity of gas diffuser layer allows more oxygen to diffuse across the catalyst layer and improves the cell performance. A thin gas diffuser layer thickness is better than a thick one, because too thick gas diffuser layer makes the transport route longer and resulting in less oxygen could participate in the catalyst and then reduce the cell performance. Considering catalyst layer thickness, catalyst layers that are either too thin or too thick do not give satisfactory results, because a thin layer would lead to lower reaction rate, while a thick layer would form higher Ohm resistance. Therefore, there exists an optimum thickness of catalyst layer. Considering the membrane thickness, it is found that a thick layer would increase cell resistance and eventually reduce the cell performance. Finally, base on the results at different locations it is discovered that oxygen distribution in the gas channel always influences the cell performance. Hence, the discussions and analysis of gas channel design for fuel cells are necessary.
Since the cell present study does not consider water effect, all result presented in this work were based on the situation without water.
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