- 學位論文
燃料電池重組器性能分析與觸媒影響之研究
An Experimental Study of the Performance on Reformer of Fuel Cell and Effect of Catalysts
摘要
燃料電池能直接將燃料中的化學能轉變為電能，其中以甲醇為原料的質子交換膜燃料電池（PEMFC）更是具有反應溫度低、能量密度高等多項優點，是未來取代傳統發電方式的理想裝置。 為了提供燃料電池所需的富氫氣燃料，本研究設計一小型燃料重組器系統。其特色為系統內有一逆流式熱交換器，可讓低溫的反應物與反應後高溫的產物做熱交換，如此可增加系統熱效率，並免去蒸發器與凝結器兩元件。並設計一反應器以探討反應溫度、反應物進料率、反應物中甲醇濃度、觸媒種類、觸媒擔體孔徑密度、和觸媒擔體長度，等六項參數彼此之間的關係。 實驗結果顯示，當反應溫度越高、觸媒擔體孔徑越密時，則甲醇轉化率隨溫度之增加而增加，氫氣產量也隨之變大。其中單位孔徑密度400 CPSI（Cell per Square Inch）之觸媒擔體在反應溫度從200℃增加至320℃時，甲醇轉化率由14％增加到83％，氫氣產量由0.027（mole/min）增加到0.137（mole/min）。但200 CPSI之觸媒擔體在反應溫度從200℃增加至320℃時，甲醇轉化率僅由16％漸進增加到45％。 在反應物的濃度方面，以S/C比（Steam to Carbonate Ratio）為1.18左右為較佳，反應溫度320℃時甲醇轉化率可達83％；超過此S/C比越大反應效率越差，S/C比在1.9，反應溫度320℃時甲醇轉化率僅達42％。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。另外，在測試的三種反應觸媒中，以銅-鋅和鉑-鈀混合的觸媒在各方面的表現都較為穩定，是小型重組器系統較佳的選擇。 觸媒擔體長度明顯越長對反應效率越好，觸媒擔體長度105mm時，甲醇轉化率僅需280℃即可高達92％，在320℃時轉化率更達到反應率94％，氫氣產量也高達0.19（mole/min），為實驗中最佳之實驗數據。
並列摘要
Full cell converts the chemical energy within the fossil fuel directly to electrical energy without combustion. There are several different kinds of fuel cells. Among them, PEMFC with the advantages of low temperature of reaction and high density of energy, and can satisfy the requirements for the power supply of a portable electronics, has drawn the most attention recently. Though the reforming process, a methanol could be converted into a hydrogen-rich gas for PEMFC. In this research, a heat exchanger has been designed to make the heat transfer from hydrogen-rich gas to methanol solution and take the place of condenser and evaporator. Effects of experimental parameters of the design methanol reformer, such as reacting temperature, methanol feeding rate, steam-to-methanol mole ratio (S/C) , kinds of catalysts, cell per square inch of catalyst supports and length of catalyst supports, are investigated and the performance of the methanol reformer is evaluated. The experimental results show that the methanol conversion and hydrogen yield increase with reacting temperature and cell per square inch of catalyst supports. When the steam-to-methanol mole ratio is set at 1.18, reacting temperature 320℃, the maximum of methanol conversion rate obtained 83％, and when the steam-to-methanol mole ratio is set at 1.9, the maximum of methanol conversion rate only obtained 42％. The methanol conversion increase with methanol feeding rate, decrease with hydrogen yield. The experimental results also show that the methanol conversion increase obviously with the length of catalyst supports. It has been discovered that the optimal conversion rate which occurs when the length of catalyst supports is set at 105 mm is 94％ and the hydrogen yield is around 0.19 mole/min.