| Summary: | 碩士 === 中原大學 === 機械工程研究所 === 89 ===
The purpose of the thesis is to study the effects of the oxidant transport in a ribbed channel of fuel cell cathode. Water produced inside the cathode will arrest the oxidant diffusion into the electrolyte and lead lower power generating performance. In this study, we focus on the effect of enhancing the shear stress and the total pressure to take water away from the fuel cell cathode channel. Examining the flow profiles in the channel may give a better channel structure that can solve the problem of cathode flooding.
PHOENICS software package is employed to simulate the oxidant transport in a cathode channel. Both laminar (Re=1500) and turbulent (Re=3000) flow are examined. The geometry of the channel is either smooth or with ribbed 1/9 to 1/2 height of the channel width. Oxidant consuming rate is a ranging from 10% to 30%.
The results show that: (1) channel with ribs has higher shear stress, total pressure, and pressure drop than smooth channel, which means ribbed channel can take away more liquid water than nonribbed channel，so that can improve the performance of fuel cell. (2)The shear stress, total pressure, and pressure drop are increased as the rib height is raised. (3) The shear stress, total pressure, and pressure drop is smaller as oxidant consumed ratio is higher. (4)Turbulent flow case has higher shear stress, total pressure, and pressure drop than laminar flow.
|
|---|
