| Summary: | 博士 === 元智大學 === 機械工程學系 === 95 === The performance of direct methanol fuel cell (DMFC) was affected by many factors; include membrane electrode assemblies, methanol crossover, concentrations, electrolytes, catalysts, temperatures, flow field design and so on. In this study, we do lots of investigations of the effects of operating parameters, electrolytes (Nafion 211, 112, 117, Nx-424), flow fields designs and combinations on DMFC performance and efficiency.
According to the results, we find the performance increase with the increasing temperature and decreasing membrane thickness no matter the thin membrane cause more methanol crossover. However, the tendency of methanol crossover can be determined by open circuit voltage and crossover current densities measured via electrochemical oxidation technique. In addition, the experiments with flow field designs and different stoichiometric factor were investigated to see the influences of the DMFC with the different combinations as a result of entirely different characteristic of reactants and products in anode and cathode of DMFCs. Among these, cathode flow field holds higher influence than that of anode. However, more detailed experiments needed to be done to find out the reasons. In this study, CFDRC half-cell models are adopted to simulate the flow phenomena within flow fields. We find that gas is well distributed within serpentine flow field while barren region are observed within parallel flow field. In the conclusion, balance the energy demand and the performance export of DMFCs system by using grid flow field design to supply oxygen to the cathode can be verified.
|
|---|
