燃料電池微型重組器設計與性能測試

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

袁國傑(Kuo-Chieh Yuan)

指導教授 ： 蘇金佳

國立臺灣大學/工學院/機械工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.00986

摘要

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。
將甲醇重組為氫時，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。
上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。

關鍵字

質子交換膜燃料電池 ； 氫 ； 微型重組器 ； 觸媒 ； 純化

並列摘要

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.
To 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.
The 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.
The 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.

並列關鍵字

PEMFC ； Hydrogen ； Micro-reformer ； Catalyst ； Purification

參考文獻

[15] 黃智勇，”實驗研究小型重組器產氫之性能”，博士論文，國立臺灣大學機械工程研究所，中華民國96年

[2] X.F. Peng and G.P. Peterson, ”The effect of thermofluid and geometrical parameters on convection of liquid through rectangular microchannels”, Int. J. Heat Mass Transfer, 38, 1995, pp.755-758.

[3] X.F. Peng and G.P. Peterson, “Convective heat transfer and flow friction for water flow in microchannel structures”, Int. J. Heat Mass Transfer, 39, 1996, pp.2599-2608.

[5] 邱輝煌、賴維祥與陳泓政，”燃料電池用之甲醇重組器氫氣產生之研究”，碩士論文，國立成功大學航太工程研究所，中華民國91年。

[6] Y.M. Lin and M.H. Rei, “Study on the Hydrogen Production from Methanol Steam Reforming in Supported Palladium Membrane Reactor”, Catalysis. Today, Vol. 67, pp. 77-84 (2001)