叉合型流場於質子交換膜燃料電池之陰極半電池的參數探討; The parametric study in the cathode of PEMFC with the interdigitated flow field

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题名:	叉合型流場於質子交換膜燃料電池之陰極半電池的參數探討;The parametric study in the cathode of PEMFC with the interdigitated flow field
作者:	林弘基;Hong-Ji Lin
贡献者:	機械工程研究所
关键词:	質子交換膜燃料電池;叉合型流場;淨水傳輸效應;質子電場效應;net water transport effect;PEMFC;protonic field effect;interdigitated flow field
日期:	2006-01-10
上传时间:	2009-09-21 11:50:23 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本文以二維數值模擬分析質子交換膜燃料電池的陰極半電池搭配叉合型單相流場，計算區域包括擴散層、催化層和薄膜。數值解著重在探討淨水傳輸效應、質子電場效應和不同參數（入口壓力、薄膜含水量、擴散層和催化層的孔隙率以及Nafion材質中不同亞硫酸根離子濃度）對電流-電壓曲線的影響。數值結果發現淨水傳輸效應對電池性能幾乎沒有影響，但是質子電場效應會強烈壓抑入口流入的氧氣，因而降低電池的電流密度。增加薄膜含水量會提高過電位，使電流密度上升。而入口壓力愈高，入口氧氣濃度亦隨之增加，對於歐姆極化的影響降低，且降低在催化層中逆流的效應。增加擴散層和催化層的孔隙率對於氧氣的擴散能力加強，在濃度極化時可有效提供氧氣參與反應。在催化層內由於質子由高電位往低電位移動會影響氣體流動方向，故本文探討在催化層不同亞硫酸根離子濃度（可視為Nafion材質的成分指標）對於質子電位的影響，有別於一般燃料電池的研究認為Nafion材質中亞硫酸根離子濃度愈高，質子傳導愈多，燃料電池性能愈好。但本文的數值解卻顯示降低亞硫酸根離子濃度，對造成在催化層內逆流的影響愈小，可有助提高電流密度。 A numerical study is performed to analyze the half-cell model for the proton exchange membrane fuel cell (PEMFC) with an interdigitated gas flow field. The modeling domain consists of the diffuser layer, catalyst layer and the membrane. Numerical simulation is focused on effects of the net water transport, protonic field and various parameters on the performance of current density-voltage (I-V) curve. Simulations reveal that the net water transport virtually has no any effect on the I-V curve. However, the inflow oxygen amount is strongly blocked by the action of protonic field and hence the current density is reduced. The increasing of water content in the membrane enhances the overpotential, thus increases the current density. The higher inlet pressure results in more oxygen concentration, and reduce the reversed flow in the catalyst layer. The overall effects minimize the ohmic polarization effect. Increasing the porosity of the diffusion layer and the catalyst layer will enhance the oxygen diffusion which effectively provide oxygen for reaction when the concentration polarization occurred. In the catalyst layer, the direction of the gas flow is affected by the proton migration from the high electric potential to the low electric potential. Results of the protonic field effect due to alteration of the SO3 concentration (a composition index to characterize different type of Nafion) in the catalyst layer are different from others investigation and its explanation is discussed.
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