微型質子交換膜燃料電池為最適用於可攜帶性電子產品之潔淨科技,為提供其氫氣來源須搭配穩定微型氫氣產生設備,本研究建置一套微型甲醇蒸氣重組系統,藉此探討在不同操作條件下對於甲醇轉化率與氫氣產生率之影響,其設定實驗參數分別為反應溫度、甲醇水溶液濃度、甲醇水溶液進料率、流道長度與微流道截面尺寸。 甲醇蒸氣重組反應為甲醇水溶液經重組後生成氫氣與二氧化碳,為此本實驗設計一三上三下蛇行流道之重組反應器,其尺寸設計為100mm×120mm×15mm,單流道截面則有0.75 mm *0.75 mm與0.75 mm *1.5mm,流道長度分別為633mm、1015mm與1392mm,觸媒選擇為CuO-ZnO-Al2O3,其塗佈量上下蓋分別為0.08g與0.14g。 實驗結果顯示,在實驗設定之200-280℃區間,隨著反應溫度增加,甲醇轉化率與氫氣產生率均大幅提升。在280℃時,甲醇進料率0.005ml/min,其轉化率接近100%,氫氣產生率5.4sccm;若甲醇進料率0.02ml/min,其轉化率83.4%,但氫氣產生率18.0sccm,約可供給微型質子交換膜燃料電池產生22.5W功率,為本實驗最高值。反應物濃度方面,水對甲醇比α=1.4相對於其他濃度,如較高之α=1.6與較低之α=1.0、1.2,在不同操作條件下,有較好之甲醇轉化率表現。在進料率方面,甲醇轉化率隨著甲醇進料率調升而降低,氫氣產生率則隨著甲醇進料率調升而上升。反應時間方面,在化學反應初期,增加化學反應的時間能有效促進系統之轉化率,加長反應器流道長度與增大流道截面尺寸則能增加反應流體之反應時間,提高蒸氣重組系統之甲醇轉化率與氫氣產生率。
Reformed methanol fuel cell (RMFC) technology uses a steam reforming reactor to generate fuel-cell-ready hydrogen from a highly concentrated methanol solution. For PEMFC at portable electronic devices application, it is needed to develop micro RMFC which will work with micro PEMFC. At this research, a micro reformer was build for experimental study, which was construed with three channels included serpentine flow and has the dimension of 100mm×120mm×15mm. The micro channels have a width of 0.75mm and two kinds of depth, i.e. 0.75mm and 1.5mm. Three length of the channel was designed as 633mm、1015mm and 1392mm. Commercially available CuO-ZnO-Al2O3 catalyst was coated inside the micro channels for steam reforming. The catalyst was used about 0.08g for top plate and about 0.14g for base. The experimental results show the methanol conversion and hydrogen production rate increase with reaction temperature raise at 200-280℃. When reaction temperature at 280℃, 0.005ml/min feeding rate cause that the methanol conversion reaches 100% approximately. But as feeding rate set 0.02ml/min, the methanol conversion was 83.4%, and hydrogen production rate reaches 18.0sccm which can produce power output of 22.5W from micro PEMFC. The experimental results also show that the methanol conversion decrease and the hydrogen production rate increase with feeding rate raise. For different concentration, the water to methanol ratio at 1.4 has optimal methanol conversion. Increasing the length of channel and the dimension of cross section would add the chemical reaction time, and then increase the methanol conversion and hydrogen production rate.