Effects of novel flow field with channel contraction on cell performance of PEM fuel cells

• Main Authors: Po-Chiao Chiu, 邱柏橋
• Other Authors: Hung-Yi Li
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/09698106208486567519

碩士 === 華梵大學 === 機電工程研究所 === 95 === In this thesis, the computational fluid dynamics software CFDRC is used to establish a three-dimensional numerical model of the proton exchange membrane fuel cell. The effects of the different flow field designs (parallel flow field, serpentine flow field, and Z-type flow field) and flow fields with outlet contraction on the phenomena of the electron/mass transfer in the proton exchange membrane fuel cell are investigated. Different height outlet contraction ratios, length outlet contraction ratios and cathode inlet flow rates are employed to investigate their influences on the liquid water removal, the fuel cell performance, and the pressure drop from the inlet to the outlet of the flow channel. Superior outlet contraction ratios and inlet flow rates for the three flow fields are inferred. For the flow channel outlet height contraction design, owing to the reduction of the cross-section of the outlet contraction region, the fuel velocity increases, and the liquid water removal accelerates. Thus, the fuel reached the catalyst layer to participate the reaction increases and the occurrence of the mass transport losses is delayed which makes the performance of the fuel cells raise. As the flow channel outlet height contraction ratio δH increases, the cross-section of the outlet contraction region decreases. Thus, the velocity increases and the pressure drop enlarges. For the flow channel outlet length contraction design, the outlet contraction region increases as the flow channel outlet length contraction ratio δL increases. Thus, the amount of the liquid water removal increases and the performance of the fuel cell enhances. Besides, when the cathode inlet flow rate increases, the oxygen for the electro-chemical reaction is more sufficient in the flow channel, and the liquid water removal is more effective in the gas diffuser layer, which enhances the performance of the fuel cell.