- 學位論文
直接甲醇燃料電池陽極端微噴霧式進料系統製作
Direct methanol fuel cell anode mist jetting type fuel supplement system fabrication
摘要
摘要 燃料電池由陽極、陰極與電解質所構成，可將電化學能直接轉化成電能。相較於傳統電力有高電能轉換效率，長時間操作與產生廢熱再利用電力共生等優勢。在眾多類型中又以具有低溫操作能力及高能量密度的直接甲醇燃料電池最有微型化的潛力與商機，供可攜式用品市場使用。 現行直接甲醇燃料電池進料模式大部分為小型蠕動馬達推動液體，流經高純度石墨製流道板後進入陽極發生反應，因此產生許多問題；在材料端的問題有：1.高純度石墨板製作加工不易2.系統增重，石墨塊厚度達3cm以維持切割時材料強度，使單一電池重達2公斤不便攜帶。在系統端的問題有: 1.傳統蛇行流道板(水平進料方式)產生燃料被氣泡或是雜質阻塞，使電性表現下降。2.因流道蜿蜒有一定長度使前後段會產生濃度及溫度梯度，因此燃料在流道各處反應環境不同，導致反應不均勻。 本研究希望發展出新型直接甲醇燃料電池陽極端進料模式，以整合壓電材料產生超音波震盪來達成垂直進料解決以上問題。1.超音波震盪垂直進料可避免因水平進料而產生的阻塞情形。2.垂直進料不需通過蜿蜒流道讓燃料接觸觸媒反應。不因流道長而有溫度、濃度梯度問題。3.噴霧進料可達到DOD(droplet on demand)效果有效的進料及廢物移除。可望有較高的單位時間反應及放電效率。 先以巨觀噴霧測試電池組放電可能性，接著檢測燃料受超音波震盪後是否產生影響。然後製作各微小化部件:1.噴霧震盪片作動參數能耗分析。2.微噴孔片設計並製作改良。3.噴孔片表面處理與液珠噴射現象分析。4.各式攝影(巨觀DV、顯微鏡、高速攝影機)分析液珠噴射狀況，最後以電路控制方式導入週期性進料概念，經各部件微小化並整合成全系統後，可提供直接甲醇燃料電池高效率及高便利性的進料方式。 Abstract Fuel cell is a power generating device composed by anode, cathode and electrolyte. It can directly change electro-chemical energy into electricity. Compared to traditional power generating devices, it has many advantages such as high transformation efficiency, longer time duration and waste heat recycle ability. Since direct methanol fuel cell has low temperature operation ability and high energy density. Among all kinds of fuel cells it has most potential to be miniaturization for portable device usage. Nowadays the major fuel refilling mode for direct methanol fuel cell(DMFC) is using syringe pump to push liquid through high purity carbon flow channel plate into anode for electro-chemical reaction. This method produces many problems. For material’s aspect: 1. Manufacture difficulty for high purity carbon flow channel plate. 2. The carbon plate must be in 3cm width to maintain material strength in cutting, which causes single cell weighing 2 kg and limits its portable application. For system’s aspect: 1.Fuel will be blocked by bubbles or impurities in traditional flow channel. This phenomenon causes electrical performance degradation. 2. Serpentine flow channel resulting concentration and temperature level between the start and end of it. This condition causes different reaction surroundings and inconsistent reaction in the channel. We hope to develop new type direct methanol fuel cell anode fuel supplement system in this research. Solving all the mentioned problems by integrating piezo-electrical material produces ultrasonic vibration to accomplish vertical fuel supplement. 1. Vertical fuel supplement can avoid fuel congestion caused by parallel supplement. 2. Without flow channel avoiding temperature and concentration gradient. 3. Mist jetting supplement have droplet on demand effect can refill fuel and move junks efficiently. Thus, we can have quicker reaction time and higher electrical transforming efficiency. 4. No more complicated system and massive equipment for a single fuel cell. First, we integrate macro mist jetting supplement method with fuel cell system and test functional probability, than checking whether ultrasonic vibration will cause fuel transformation or not. The experiment procedure in micro device fabrication as follows. 1. Piezo-electrical actuating condition analysis.2.Micro nozzle plate design and innovate. 3. Nozzle plate surface treatment and droplet jetting condition analysis. 4. Droplet jetting condition analysis by Digital Camera, Microscope and high-speed recorder, then via integrated with electro-controlling system realize periodic fuel supply concept. After all part fabrication and integration into whole system. Higher efficiency and much convenient fuel supplement model in direct methanol fuel cell could be established.