| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 91 === Abstract
The characteristics of PEMFC stacks in different designs and operational conditions are studied and manufactured in this thesis. There are many factors that affect the PEMFC performance. They include the familiar humidity, the torque, the inlet pressure, the geometries of inlet ports and the flow channels in reaction regions, the cell numbers of the stacks, the type of the oxidizer and its flow rate. To understand the performance characteristics of stacks the voltage and current density will be measured as well as the interior temperature of stacks in this research.
The membrane exchange assembly (MEA) with Nafion 112, anode Pt 0.4 mg/cm² and cathode Pt 1.0 mg/cm² is used in these experimental works. The experimental results display that increasing the applied torque will reduce the contact resistance between bipolar plate and diffusion layer but increase the difficulty of gas penetrating into the reaction region beneath the bipolar rib. So proper torque is necessary to obtain the best voltage output. The voltage vs. current density also increases as the inlet pressure increases, but its effect will reduce when the inlet pressure increases over 2atm. The geometry and size of inlet port to each cell for a multi-cell stack will influence the voltage output, especially in high current density, so that special attention is needed in designing inlet port.
When the air is used as an oxidizer, the fan with a high rotation speed is helpful in an open circuit design. The high air volume flow rate can avoid that the voltage output decays greatly in high current density. Increasing the cell number may cause extra internal resistance due to assembling improperly and reduce the voltage output. So special attention is also needed in assembling.
Keyword: Proton Exchange Membrane Fuel Cell Stacks
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