Transient Analysis of Cell Performance of PEM Fuel Cell with Different Serpentine Flow Field

• Main Authors: Ping-Chun Hsieh, 謝秉鈞
• Other Authors: Hung-Yi Li
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/15310981801466345618

碩士 === 華梵大學 === 機電工程學系博碩專班 === 99 === In this thesis, a commercial software package of CFDRC was used to simulate the three-dimensional, two-phase, transient transport pheno-mena of proton exchange membrane fuel cell. The effects of cathode flow field design and the load-change-rate on the transient characteristics of proton exchange membrane fuel cell are examined in details. The tran-sient response time and the local fuel distributions were then obtained to understand the overshoot phenomenon of the current density of the PEM fuel cell. Predicted results show that when the fuel cell voltage operates at 0.7 V, the low current density distributions was obtained due to the weak electrochemical reaction. When the voltage drops from 0.7 V to 0.5 V, the electrochemical reactions become severe, resulting to the overshoot phenomenon, thus higher local current density was obtained. To ensure sufficient oxygen supply for the fuel cell reaction, higher oxygen concen-tration in the cathode catalyst layer and the diffusion layer is necessary. Therefore, greater load-change rate leads to shorter transient response time and larger overshoot phenomenon were observed. Otherwise, small-er load-change rate induces to longer transient response time and smaller overshoot phenomenon were interpreted. For the baffle effects, the predicted results indicate that better cell performance is noted for the flow field design with more baffle. As a consequence, relatively larger overshoot phenomenon and longer tran-sient response time were showed. Besides, by varying the width ratio of cathode flow channel, the PEM fuel cell with larger channel width ra-tio results in better cell performance and more obscure overshoot pheno-menon were recorded. However, lower flow rate was resulted and the fuel cell required longer time to achieve steady state was obtained.