臺灣博碩士論文加值系統

本研究分析一個二維、穩態高溫型質子交換膜燃料電池模型，以多重物理量有限元素分析軟體COMSOL Multiphysicsy作為分析工具，討論區域包括氣體擴散層、觸媒層及質子交換膜，氣體擴散層為多孔性的碳纖維導電材料，並以Agglomerate 模型描述觸媒層結構，使用PBI (polybenzimidazole)膜參雜磷酸作為質子交換膜，其中包括氣體在電解質及磷酸溶液中的擴散係數及溶解度的修正，針對物種的質量傳遞方程式、Darcy-Brinkman方程式、Maxwell-stefan方程式、電荷守恆方程式及能量方程式，探討在各種不同參數條件下，對電池性能的影響。
本文採用指叉型流道，以不同的溫度、磷酸參雜等級(doping level)、磷酸與水的重量百分比、有效反應面積、容積熱傳係數等因素，發現提高溫度、增加磷酸參雜等級為主要影響電池性能參數，此外，提高陽極及陰極之單位體積電流密度比將導致在高電流密度時嚴重之濃度極化。

Fuel cells operated at high temperature provide two main advantages as compared with their low-temperature counterparts: no water management problem and high carbon monoxide poison resistance at the anode. In this study, a two-dimensional model was developed to study the performance of fuel cell operated at temperature in the ranges of 120 to 190℃ using phosphoric acid doped polyberzimidazole (PBI) membrane. Coupled mass conservation, fluid flow, species transport, and charge conservation were solved numerically. An agglomerate model was used to describe the detail electrochemical reaction inside the catalyst layer. All the major transport phenomena were taken into account. Effects of the operation parameters such as temperature, reference current density, acid doping level, water content in acid solution, effective agglomerate surface area, agglomerate size, and volumetric heat transfer coefficient between solid and gaseous phases on the fuel cell performance in terms of current-density and current power output curves were examined in detail.

Based on the simulated results, it was found that better fuel cell performance can be obtained using high doping level of the acid solution, high effective agglomerate surface area and high anode reference current density. However, the concentration polarization on the cell output becomes more effective under these circumstances. The results also indicated that increasing the heat transfer between the solid and gas phases can improve cell output which suggested that the cell operated with high reactant flow rates would be preferred. In contrast to these parameters, water content in the acid solution and agglomerate size produce insignificant effect on the cell performance.

摘要 i
Abstract ii
目錄 iii
圖目錄 v
表目錄 vii
符號表 viii
第一章 緒論 1
1.1 前言 1
1.2 文獻回顧 7
1.3 研究目的 10
第二章 理論分析和數值方法 11
2.1 物理模型及基本假設 11
2.2 統御方程式 13
2.2.1 氣體擴散層 13
2.2.2觸媒層 16
2.2.3質子交換膜 24
2.2.4 影響質子交換膜燃料電池性能之因素 24
2.3 邊界條件 25
2.3.1氣體擴散層 26
2.3.2 觸媒層 27
2.3.3 質子交換膜 28
2.4 數值方法 30

第三章 結果與討論 31
3.1陽極體積電流密度與陰極體積電流密度的比值對性能的影響 32
3.2 溫度對性能的影響 32
3.3 磷酸參雜等級對性能的影響 33
3.4 磷酸與水的重量百分比對性能的影響 33
3.5 容積熱傳係數對性能的影響 33
3.6 Agglomerate 半徑對性能的影響 34
3.7 觸媒層有效反應面積aratio對性能的影響 34
第四章 結論與建議 49
4.1 結論 49
4.2 建議 49
參考資料 50

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