| Summary: | 碩士 === 中國文化大學 === 機械工程學系數位機電碩士班 === 106 === This research successfully developed a single channel three dimensional model of high temperature proton exchange membrane fuel cells. The effects of channel blocks and air velocity on the cell performance were studied via the multi-physics coupling software, COMSOL Multiphysics®. The simulation results were verified with experimental data and thus had good credibility. In addition to polarization curves, the fundamental characteristics, including the oxygen concentration distribution, water vapor concentration distribution, air velocity vector and the current density distribution, were discussed as well in this work.
The simulation results show that installing the channel blocks with a blocking ratio higher than 70% increases the cell performance at high air velocities. Under low air velocities, increasing the blocking ratio of the channel block increases the local current density and oxygen utilization in the upstream flow channel, but however causes an increase in cathodic mass transport resistance in the downstream flow channel, leading to increasing the overall mass transport overpotential and decreasing the cell performance. At the air velocity of 0.8 m/s, the cell performance at 0.3 V increases by about 8.8% as the blocking ratio is elevated from 0% to 100%. By contrast, the cell performance at 0.3 V decreases by about 23.1% as the blocking ratio is elevated from 0% to 100% at an air velocity of 0.2 m/s. Moreover, the sensitivity of cell performance to the air velocity increases with increasing the blocking ratio of channel block because the sensitivity of mass transport resistance to the air velocity increases with increasing the blocking ratio.
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