Design and Performance Test of a Micro-Reformer for Fuel-cell Application

PEMFC可以應用於微型燃料電池，原因是PEMFC電力密度高，而唯一要克服的是它需要攜帶足夠的氫氣能源。現代甲醇微型重組器可克服氫氣攜帶量的瓶頸，而重組可以利用適當的觸媒改善，其關鍵技術為甲醇重組觸媒種類與塗佈、反應器流道設計及系統控制，是值得研發者繼續克服的問題。甲醇重組為氫時，必須先將甲醇與水混合，並加熱成為氣態，然後才進入反應器，從中與觸媒接觸產生反應。因此，反應物溫度、甲醇與水的比例、反應物與觸媒的接觸面積與時間長短對於整體反應效率有極大的影響。因此，本研究將針對這些因素設計並建立一個微型重組系統，此微型甲醇重組器尺寸設計為100mm×120mm×15mm，其流道尺寸則為750μm×150μm×60mm，而塗佈之觸媒重量約為10mg左右，且觸媒CuO-ZnO-Al2O3係直接塗佈於流道上，以減少重組器的體積、製作成本。 實驗結果顯示，反應溫度越高，則甲醇轉化率隨溫度之增加而增加，氫氣產量也隨之變大。在反應溫度從180℃增加至260℃時，甲醇轉化率由5％增加到72％，氫氣產量由0.80E-04（mole/min）增加到7.50E-04（mole/min）。進料率方面，反應物進料率增大，氫氣產量也會跟著增加，但卻會導致甲醇轉化率降低。反應器面積明顯越大對反應效率越好，當反應面積為5.70E+03mm2、溫度增加至260℃、進料率為0.01ml/min時，甲醇轉化率即可高達85％，在進料率為0.50ml/min，氫氣產量也高達2.90E-03（mole/min），為實驗中最佳之數據，此氫氣產量也足以供應一般微型燃料電池的氫氣需求量。述會影響整個重組性能的因素都將逐一加以測試研究，而系統的性能則以甲醇轉化率、氫產生率及產物中的CO濃度為指標。最後則將甲醇的重組與其氫產物的純化併入一微型燃料電池，以測試整個系統的性能，並試圖找出最佳的匹配。PEMFC may be applied in micro-scale for its high density of energy. However, the disadvantage of the difficulty in storing gaseous hydrogen in the PEMFC system must be overcome. Fortunately, the problem may be solved by a fuel-processing system for generating hydrogen through the reformation of liquid methanol. The reforming process may be greatly improved by the use of some proper catalysts. The key points for the reformation are, therefore, the type and amount of the catalyst, the design of the reacting channel, and the control of the processing system.o generate hydrogen from methanol, the latter must be mixed with water and the solution of the reactants must be heated into gaseous state before entering the reactor. The temperature of the reactants and the ratio between methanol and water are thus also important. Furthermore, the area and time of contact between the reactants and the catalyst may affect the reaction rate significantly. The research project is, therefore, the dimensions of the reforming sub-system set up for the investigation will be 100mm x 120mm x 15mm, while those of the flow channels will be 750μm x 150μm x 60 mm. The catalyst CuO-ZnO-Al2O3 of about 10mg will be directly coated on the flow channel to save space and cost.he experimental results show that the methanol conversion and hydrogen yield increase with reacting temperature. When reacting temperature is set at 260℃, the maximum of methanol conversion rate obtained 72％ and the maximum of hydrogen yield obtained 7.50E-04（mole/min）. The methanol conversion increase with methanol feeding rate, decrease with hydrogen yield. The experimental results also show that the methanol conversion increase obviously with reacting area. It has been discovered that the optimal conversion rate which occurs when the reacting area is set at 5.70E+03mm2、the feeding rate is set at 0.01 ml/min、the reacting temperature is set at 260℃ is 85％ and the hydrogen yield is 2.90E-03 mole/min when the feeding rate is set at 0.5 ml/min.he effect of the above-mentioned factors, which may affect the performance of the complete reforming system, will be experimentally investigated within proper ranges, while the performance indicators of the system will be the conversion rate of methanol, the yielding rate of hydrogen, and the concentration of CO in the final products. Finally, the complete reforming system will be incorporated into a micro-PEMFC and tests will be conducted to show the appropriateness of the design.目錄容 頁次文摘要.....................................................................................................I文摘要....................................................................................................II錄..........................................................................................................IV目錄.....................................................................................................VII目錄....................................................................................................VIII號說明................................................................................................XIII一章 緒論............................................................................................1.1 燃料電池...................................................................................1.2 微型重組器...............................................................................3 1.3 重組器反應機制與原理...........................................................5.3.1蒸汽重組法............................................................................6.3.2部分氧化重組法.....................................................................7.3.3自發熱重組法.........................................................................7.3.4 甲醇重組方法比較.................................................................8 1.4 研究動機...................................................................................9二章 文獻回顧..................................................................................10.1 重組器的設計及實驗研究.......................................................10.1.1 蒸汽重組法.........................................................................10.1.2 自發熱重組法…..................................................................12.2 微型重組器的設計及實驗研究.............................................13.3 重組器的應用.........................................................................14.4 微型重組器的設計目標……………….................................15 2.5 反應速率與溫度……………….............................................16三章 實驗設備與過程......................................................................19.1 甲醇溶液供應系統.................................................................19.1.1 微甲醇水泵.........................................................................19.1.2 管柱加熱器.........................................................................20.1.3 甲醇水槽............................................................................20.2 重組反應系統……..................................................................20.2.1 反應器…….........................................................................20 3.2.1.1 反應器本體…...........................................................21 3.2.1.2 防洩環…..................................................................21 3.2.1.3 ㄇ型加熱器..............................................................21 3.2.1.4 隔熱裝置….............................................................22 3.2.1.5 溫度控制器..............................................................22 3.2.1.6 熱電偶…..................................................................22.2.2 物理乾燥器….....................................................................22.2.3 觸媒種類………..................................................................23.3 氣體收集系統.........................................................................23.3.1 真空壓力幫浦......................................................................24.3.2 氣體收集瓶.........................................................................24.4 量測設備.................................................................................24.5 實驗流程.................................................................................25四章 結果與討論..............................................................................27.1 甲醇轉化率的計算……………….........................................27.2 蒸汽重組反應………………………………………….........29.2.1甲醇蒸汽重組設定測試與分析..…………………................29.2.2 系統反應溫度…………………........................................30.2.3 甲醇水溶液進料率的影響…………………………..................32.2.4 微流道反應面積與空間速度………………………..................34.2.5 甲醇蒸汽重組氣體成分………………………………...............36.3 觸媒種類與穩定性.................................................................36.4 甲醇水溶液濃度( 比)的影響..............................................37.5 甲醇反應器之熱效率.............................................................38五章 結論與建議..............................................................................40.1 結論.........................................................................................40.2 建議.........................................................................................41考文獻..................................................................................................43表..........................................................................................................48圖..........................................................................................................57錄A 誤差分析...................................................................................93錄B 微甲醇水泵...............................................................................9