| Summary: | 碩士 === 元智大學 === 機械工程學系 === 93 === A quasi two-dimensional half-cell model has been developed in this study. A half-cell model which contains the cathode gas channel, gas diffuser, catalyst layer, and the membrane is considered. To account for the effect of gas velocity in the gas channel, axial convection is included in the oxygen transport equation of the gas channel. The analytical solutions are presented in the form of infinite series, and expressions for the oxygen mass fraction distribution in the gas channel, gas diffuser, and catalyst layer, and membrane phase potential and current density in the catalyst layer and membrane have been derived. Furthermore, two different models of the ion conductivity of ionomer have also been studied. The effect of the ion conductivity is analyzed on the oxygen concentration, phase potential and current density distributions. The effects of other parameters, such as operating pressure, diffuser thickness, etc., have been investigated on the performance of fuel cell in the present study. The results show that cell perfomance improves with higher inlet velocity, higher surface potential, higher operating pressure, higher GDL porosity and thinner diffuser. It is also found that oxygen mass fraction, membrane phase potential and current density in catalyst layer are the same no matter the ion conductivity of ionomer is linear variation or a constant. However, the larger value of the ion conductivity of ionomer will result in the higher current density.
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