Experimental Study of the Effect of Flow Variables and Screw Torque on the Performance of DMFC

直接甲醇燃料電池（DMFC）以甲醇水和氧氣作為反應物，因使用方便，而且沒有氫氣爆炸的危險，適合個人隨身電子產品，未來應用潛力無窮，近年來相關研究蓬勃發展。 本實驗為提升DMFC性能，以流動變數與螺栓扭矩作為操作變數，來觀察DMFC電壓-電流關係曲線，並且紀錄極限電流。其中，流動變數包含甲醇水與氧氣的濃度、流量、壓力，而螺栓扭矩代表的是電池組的密合壓力，也就是MEA和石墨流道板之間的接觸壓力。本實驗亦探討各變數之間對DMFC影響的原因，及它們之間存在的關係。 實驗結果顯示，陽極端甲醇水濃度與流量對DMFC的影響，只有在氧氣濃度降低時顯現，影響效果較小。而陰極氧氣濃度與流量對DMFC有直接影響，氧氣濃度提升使得DMFC性能提升，影響效果較大。單向對陰極加壓有可能使接觸電阻增加，而使DMFC性能變得很差。螺栓扭矩（密合壓力）加大DMFC性能影響亦大，但扭矩大小有其限制。Direct Methanol Fuel Cell (DMFC) working based on the reactants of methanol liquid and oxygen. It provide an advantage of convenience of use and no danger of a hydrogen explosion and has extended itself as a part of the portable electronic products for individuals. Its largely potential application in the future has made it very popular in research and development in recent years. The main purpose of this experiment is to raise the performance of DMFC through change the factors of flow variables and screw torque from observation of the voltage-current curve varying and recording of the limiting current. Flow variables cover concentration, volume flow rate, and pressure of methanol liquid and oxygen, and screw torque indicates the tightness pressure of fuel cell stack that is the contact pressure between MEA and graphite channel board. This experimental study is also to explore the influence of different variables on DMFC and the relationship between them. The outcome of experiment shows that the concentration and volume flow rate of anodic methanol liquid will have an effect on DMFC only at the time while the concentration of oxygen is declining, but the concentration and volume flow rate of cathode oxygen will have a direct and large effect on DMFC. It will raise the performance of DMFC through an increase of concentration of oxygen. An unidirectional increase of pressure to cathode oxygen will make the performance of DMFC become weak because the contact resistance will possibly become large. And the soaring but limited screw torque (tightness pressure) has a great influence on the performance of DMFC.中文摘要.........................................I 英文摘要........................................II 目錄............................................III 表目錄..........................................VII 圖目錄.........................................VIII 符號說明.........................................X 第一章 緒論.....................................1 1-1 燃料電池發展簡介............................1 1-2 質子交換膜燃料電池的特點....................2 1-3 液體燃料電池................................4 1-4 DMFC工作原理................................5 第二章 文獻回顧..................................7 2-1 數值模擬....................................7 2-2 實驗量測....................................8 第三章 實驗設備與過程..........................12 3-1 電池主體...................................12 3-1.1 MEA......................................12 3-1.2 石墨流道板...............................14 3-1.3 電極銅片.................................15 3-1.4 鋁製壓力端板、螺桿螺栓...................16 3-1.5 防漏與絕緣墊片...........................17 3-1.6 電池組裝.................................18 3-2 甲醇供應系統...............................19 3-2.1 甲醇水溶液...............................19 3-2.2 甲醇水槽.................................19 3-2.3 甲醇水泵.................................20 3-2.4 甲醇水回收槽.............................20 3-3 氧氣供應系統...............................20 3-3.1 氧氣鋼瓶.................................21 3-3.2 空氣壓縮機...............................21 3-4 量測系統...................................21 3-4.1 壓力錶...................................22 3-4.2 流量計...................................22 3-4.3 電子式負載計.............................22 3-5 配管迴路...................................23 3-5.1 管路.....................................23 3-5.2 閥、接頭.................................23 3-5.3 旁通迴路.................................24 3-6 變數設定與實驗過程.........................24 3-6.1 甲醇水濃度、流量.........................25 3-6.2 氧氣濃度、流量、壓力.....................25 3-6.3 螺栓扭矩（密合壓力）.....................26 3-6.4 量測電壓與電流關係.......................26 第四章 實驗結果與分析........................28 4-1 濃度與流量分析.............................28 4-1.1 莫爾流率與反應率.........................29 4-1.2 反應物濃度與流量的影響...................33 4-2 螺栓扭矩（密合壓力）的影響..................36 4-3 陰極端單向加壓的影響........................38 4-4 最大功率....................................39 4-5 終止電流....................................40 第五章 結論與建議..............................42 5.1 結論.......................................42 5.2 建議.......................................43 參考文獻........................................45 附表............................................48 附圖............................................51 附錄A 誤差分析.................................80 附錄B 其他相關圖表.............................83 作者簡介........................................9