| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 95 === This study applies the Lattice Boltzmann Method (LBM) to simulate gas flow characteristic in bipolar plate channel of Proton Exchange Membrane Fuel Cells (PEMFCs). The calculated domain includes fluid flow, diffusion, and heat transfer performance in bipolar plate and the porous layer which is been considered as a two-dimensional incompressible steady flow under low Reynolds number. In addition, the interruption within the fluid is induced by different type of obstacles: semicircle, triangularity, and sinusoid. The simulation results show that compared to the straight geometry of a conventional gas flow channel, the wavy-like configuration enhances the transport through the porous layer. The obstacles play the role of causing interruption within the fluid field. The direction of fluid flow toward is changed by obstacles, and the recirculation region formed behind obstacles influence the fluid pass through. As mentioned above, temperature distribution within the channel is improved in local region. According to the simulation results of the heat transfer efficiency and the mass flow rate into diffusion layer, the half circle obstacle has the best performance, followed is the sine wavy obstacle and the tranglar obstacle is ranked third.
Furthermore, the present numerical results are consistent with the field synergy principle, which states that the convective heat transfer is enhanced when the intersection angle between the velocity and the temperature gradient vector decreased by inserting obstacles to fluid field. The results of heat transfer improved significantly.
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