臺灣博碩士論文加值系統

本論文以實驗方法探討非均質碳纖維雙極板應用在氫燃料質子交換膜燃料電池的性能特性。為了解碳纖維雙極板孔隙率與透氣性，本研究量測適當阻隔的碳纖維束兩側的壓力差及進氣流量，以估算碳纖維束的穿透率。此外，在不同進氣條件下，量測流道不同位置的壓力及不同位置碳纖維束陰陽兩側的電壓，以了解氣體壓力分佈與輸出電壓的關係及反應物在碳纖維雙極板的流場特性。
研究發現以碳纖維束構成平行流道或蛇行流道雙極板時，若採用空氣為氧化劑及單一進出氣口，在大電流密度時，供應給電極的氧化劑容易發生不足的現象，中下游區的輸出電壓遠低於上游區，其中以上游區輸出電壓最高，下游區次之，中游區由於氮氣較不易排除故其I-V曲線最低。在低進氣壓力下，平行流道受制氧氣不足的現象比蛇行流道明顯，功率分佈也較不均勻，尤其在靠近中間的電極性能遠比上下游區差，當提高進氣壓力時，此一現象可明顯改善。使用大面積MEA時，氧化劑不足的問題特別嚴重需要想辦法解決。
為改善陰極端單一進出氣口氧化劑容易發生不足的現象，改採用多進出氣口的平行流道，多入口流道處採用風扇補充新鮮空氣，同時在出氣口處加裝抽風裝置。此種排列可製造同一方向的氣體流動來供應新鮮空氣及吸走反應區的殘存氮氣，避免不反應氣體累積在反應區，如此可改善以空氣為氧化劑時的質傳現象，電池性能可明顯提昇。

In this thesis heterogeneous bipolar plates are applied to pure hydrogen PEMFC (called HFC) stacks. The experimental methods are adopted to study the performance and characteristics of the cell under certain operational conditions. In order to obtain the permeability of carbon fiber bipolar plates the pressure drops and flow rates are measured on the two sides of the carbon fiber bunch. A test device has been developed to separate the gas of the two sides so that the gas can only flow through the gaps between carbon fibers. Additionally, the gas pressures on the flow channel and the output voltage of each cell in several locations are measured to help us to understand their relationships. The flow characteristics of the gas reactants in these carbon fiber bipolar plates can also be understood from these measurements.
A bipolar plate with the parallel or serpentine flow channel can be formed by properly arranging the carbon fiber bunches. However, if the oxidizer is air and only single inlet and outlet in cathode chamber are designed, the oxidizer can always not be supplied sufficiently in high power density. The experimental studies display that the output voltages of cells in the midstream or downstream are far below the output voltage in the upstream. The voltage of cells in the upstream is the highest, the next one is in the downstream, and the lowest one is located in the midstream due to accumulating of nitrogen. The insufficiency of oxidizer occurs more seriously in the parallel flow channel than that in serpentine flow channel in single inlet and outlet design. The distribution of current is not uniform especially near midstream, although this phenomenon can be improved by increasing the air inlet pressure. However, the problems are hard to solve in large MEA if we just increase the inlet pressure. Another strategy is needed to solve this problem.
In order to solve the insufficient supply of air in single inlet and outlet design, multiple inlets and outlets are designed. In this design multiple entries can supply enough fresh air driven by fan, and multiple exits can exhaust inert gas by exhausting fan to avoid accumulating in a reactive chamber so that the performance of stack can be improved dramatically.

目錄……………………………………………………….……..……. ...I
圖目錄 …………………………………………………….………..….IV
論文摘要(中文)………………………………………………….…..VIII
論文摘要(英文)…………………………………………………….…..X
第一章 緒論……………………...………………….………….….1
1.1 前言…………………………………………………………….1
1.2 何謂燃料電池………………..…………………………..…….1
1.3 燃料電池的種類…………..………………………………..….2
1.4 文獻回顧..............................………………….…………..……4
1.5 研究目的..............................………………….…………..……8

第二章 質子交換膜燃料電池工作原理與架構…….….…....10
2.1 燃料電池的工作原理……………………..……………….....10
2.1.1反應效率……………………………..……………..……11
2.1.2電池理論燃料消耗量…………………..…………..……12
2.2 質子交換膜燃料電池架構……………..…………………….13
2.2.1質子交換膜………………………………………………14
2.2.2電極……………………...……………………………….14
2.2.3催化劑………….…..…………………………………….15

第三章 碳纖維雙極板與製作............…………….….…….….17
3.1 非均質碳纖維雙極板……………………..……….....………17
3.2 非均質碳纖維雙極板優點……………………….…………..18
3.3 本實驗室碳纖維雙極板之製作…………………….………..20
3.3.1 非均質碳纖維單極板之手工製作…………..................20
3.3.2 非均質碳纖維雙極板之自動化製作..............................22

第四章 量測系統…….……..……………….…..….…………....24
4.1碳纖維雙極板接觸電阻量測系統……………….…….…......24
4.2碳纖維雙極板對碳布穿透氣性流速與壓力降量測系統…….25
4.3碳纖維雙極板在不同流道設計下壓力降與電極位置性能量測………..…………………………………………..……....…26
4.4 質子交換膜燃料電池組性能量測系統…….……………..…27


第五章 實驗結果與討論...................................................……...30
5.1 內流場流道構造對性能的影響……................………...........30
5.1.1 平行流道的分析..........................................………......30
5.1.2 蛇行流道的分析..........................................………......32
5.1.3 不同進氣流量比較.......................................……….....32
5.1.4 量測性能.......................................................……….....34
5.2 進氣方式對性能的影響............................................………...35
5.3 陽極燃料進氣壓力對性能的影響...............................………37
5.4 MEA的衰退處理…....……....…...………...……..................38
5.4.1 舊MEA的處理與性能………………………………...39
第六章 結論與建議...........................................................…........40
6.1 結論………..…………………………….……..……………..40
6.1.1 透氣性的影響……………………………………..…..41
6.1.2 進氣壓力的影響………………………………………42
6.2 未來可進行的工作…..............................……….........………42
參考文獻…………………………………………………………..…....44
圖目錄
圖2.1 質子交換膜燃料電池之工作原理示意圖…….………….…47
圖3.1 非均質碳纖維雙極板示意圖…………….…………….……47
圖3.2 非均質碳纖維雙極板與電極碳布之接觸示意圖………......48
圖3.3 傳統統硬質表面雙極板與電極碳布之接觸示意圖….....….48
圖3.4 碳纖維單極熱壓機照片……………………………………..49
圖3.5 碳纖維單極熱壓條照片……………………………………..49
圖3.6 碳纖維單極板製作流程圖………….……………..……..….50
圖3.7 單束碳纖維雙極板……….…….…………………..……..….51
圖4.1 碳纖維單雙極板之接觸電阻量測設備……………….……..52
圖4.2 (a)碳纖維雙極板與(b)碳纖維單極板電阻量測示意圖……..52圖4.3 量測空氣通過碳纖維束壓力降示意圖……………….……..53
圖4.4 碳纖維加碳布與石墨加碳布之壓降與平均流速之關係...…53
圖4.5 量測空氣通過碳纖維束壓力降量測模組照片………….…..54
圖4.6 碳纖維穿透率2.245 x 10-11的壓力降圖…………….………54
圖4.7 平行流道壓力降與輸出電壓關係量測模型…….…………..55
圖4.8 蛇行流道壓力降與輸出電壓關係量測模型…...……………55
圖4.9 燃料電池性能測試系統……………………………………...56
圖4.10 6-cell banded-type 0.5 x 5 cm2 MEA…………………...…….56
圖4.11 加濕器照片………………….…..………………………..…..57
圖5.1 陰極進氣流量45ml/min時，平行流道各電池輸出電壓及功
率vs.電流密度……………………………….……...…..….58
圖5.2 陰極進氣流量100ml/min 時，平行流道各電池輸出電壓及功
率vs.電流密度……………………………………….…..….58
圖5.3 陰極進氣流量145ml/min 時，平行流道各電池輸出電壓及功
率vs.電流密度…………………………………..…...…..….59
圖5.4 陰極進氣流量45ml/min時，蛇行流道各電池輸出電壓及功
率vs.電流密度………………………………….…...…..….59
圖5.5 陰極進氣流量100ml/min時，蛇行流道各電池輸出電壓及功
率vs.電流密度………………………………….…...…..….60
圖5.6 陰極進氣流量145ml/min時，蛇行流道各電池輸出電壓及功
率vs.電流密度……………………………………...…..…..60
圖5.7 陰極進氣流量45ml/min時，平行流道不同位置上量測的
壓力降關係圖………………….………………………..…...61
圖5.8 陰極進氣流量45ml/min時，蛇行流道不同位置上量測的
壓力降關係圖………………….………………………..…...61
圖5.9 陰極進氣流量100ml/min時，平行流道不同位置上量測的
壓力降關係圖……………….…………………………..…...62

圖5.10 陰極進氣流量100ml/min時，蛇行流道不同位置上量測的 壓力降關係圖………………….………………………..…...62
圖5.11 陰極進氣流量145ml/min時，平行流道不同位置上量測的
壓力降關係圖………………….………………………..…...63
圖5.12 陰極進氣流量145ml/min時，蛇行流道不同位置上量測的
壓力降關係圖………………….………………………..…...63
圖5.13 平行流道中3rd cell，在不同進氣流量下性能與壓降之比較圖
………………….…………………………..….......................64

(a) 輸出電壓及功率vs.電流密度圖
(b) 壓力降vs.電流密度圖不同進氣流量壓力降分佈圖
圖5.14 蛇行流道中3rd cell，在不同進氣流量下性能與壓降之比較圖
………………….…………………………..….......................65
(a) 輸出電壓及功率vs.電流密度圖
(b) 壓力降vs.電流密度圖不同進氣流量壓力降分佈圖
圖5.15 平行流場與蛇形流場串聯性能圖…………….……………..66
圖5.16 分別量測6 band性能圖………….….............……………….66
圖5.17 單一電極性能圖….……………..…………………………....67
圖5.18 封閉式流場單一進氣陰極端模組照片…….....…..…...…….67
圖5.19 單一進氣時不同位置上輸出電壓及功率對電流密度分佈圖…………..….…………………………..….........................68
圖5.20 開放式流場陰極端進出口位置………..…………………….68
圖5.21 不同位置上量測的輸出電壓及功率對電流密度分佈圖..….69
圖5.22 陰陽兩極12條碳纖維接觸電阻值…..……………….……..69
圖5.23 不同空氣入口數之輸出電壓及功率對電流密度分佈圖…...71
(a) 左邊單一入口進氣…....…………………………………70
(b) 左邊兩入口進氣……...……………………………….…70
(c) 三入口進氣………………………………………………71
圖5.24 進氣風扇加抽風裝置之輸出電壓及功率對電流密度分佈圖……………………………………………………………..71
圖5.25 提供三種不同功率風扇之性能差異圖……….………....…..72
圖5.26 不同飽和蒸汽加濕溫度之性能差異圖…....………...…..…..72
圖5.27 用0.5M稀硫酸溶液煮過MEA性能差異圖…………….….73
圖5.28 陰極端供應不同的氧化劑性能圖……………...……………73
圖5.29 熱處理機照片…………………..……………...…...………...74
圖5.30 不同方法處理MEA性能差異圖…….………...…..………..74
圖5.31 用0.5M稀硫酸溶液煮不同時間性能差異圖……..………...75

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