近年來能源議題包含燃料短缺以及環境污染等議題，迫使研究和開發以減少排放和利用可再生能源/潔淨能源的戰略為主，因此在最近的研究當中，生質混合燃料時常被當作研究與探討的主題。而在生質混合燃氣方面，氫氣、一氧化碳與甲烷是最主要且常見的組成物。在先前研究，其結果顯示一氧化碳與甲烷混合燃料在固定當量比下，改變燃料比例會有遠高於個別燃料火焰速度的火焰速度總和，且相當多文獻也指出添加氫氣於燃料中會明顯提升火焰速度同時增進火焰的燃燒穩定性。因此本論文探討混合燃氣之拉伸極限影響火焰結構特性在空氣及純氧燃燒條件下，利用實驗及模擬觀察其火焰結構與燃燒特性。
當氫氣混摻比例從0 vol%增加至10 vol%，且當量比從0.4增加至0.8，火焰拉伸率為200s-1、300s-1、400s-1。從火焰現象觀察發現，隨著拉伸率的增加，流體效應明顯地使其火焰厚度變薄，火焰位置越靠近火焰停滯面(stagnation plane)並且厚度越來越薄；隨著當量比增加與一氧化碳比例增加，火焰顏色由藍色火焰轉變成橘色火焰產生，且橘色火焰的區域也隨一氧化碳濃度比例增加而擴大；而當氫氣比例的增加雖然火焰現象並無明顯變化，但從火焰厚度會隨氫氣混摻比例增加而變大；值得一提地，當拉伸率越大時，火焰外態會出現皺褶的象限。
藉由CHEMKIN Pro進行數值計算搭配GRI-mech3.0反應機構進行模擬分析。隨著氫氣混摻比例的增加至空氣及純氧燃燒條件下，雖然絕熱火焰溫度隨之增加，但增加的幅度卻不明顯，但層流火焰速度卻相對地有明顯的改變。從火焰結構的分析結果，發現其火焰速度的變化過程主要受到化學機構的改變所造成。在無氫氣混摻條件下，比較不同拉伸極限差異下，化學反應機構在火焰預熱區經由自由基分岐鏈鎖(chain branching)反應步驟R99主導，但在火焰反應區則是由R38及R99所主導；因此，在拉伸極限條件下，對衝火焰存在的因素除了流體效應外，化學反應的引響也不容小覷。在氫氣混摻條件下，在拉伸極限的流體效應下，發現化學主導反應是R38及R84，由於化學物種與自由基的濃度及化學反應變化所造成的結果；但隨著氫氣混摻比例增加，反而影響整體火焰的化學主導反應則是R84。討論在純氧燃燒條件且比較拉伸極限條件下，發現氫氣混摻比例增加時，整體化學主導反應為R38及R84，其變化皆由化學物種與自由基的濃度以及化學反應路徑變化所造成

The study is aimed to investigate the effect of hydrogen addition on bio syngas combustion at air-fuel and oxy-fuel condition. The fuel composition of syngas, including methane, carbon monoxide, and hydrogen, was specified with identical heating value. The adiabatic flame temperature, laminar flame velocity, and extinction strain rate were determined by CHEMKIN PRO with GRI-Mech 3.0. In order to discuss the diluent effect of carbon dioxide, the oxidizer condition of oxy-fuel combustion was set to 32% of oxygen and 68% of carbon oxidate, and the corresponding adiabatic flame temperature is similar to that of air-fuel combustion. The results of reaction rate showed that the reaction of OH + CO = CO2 + H would be reduced and replaced by the reaction of H + O2 = O + OH when the condition shifts from air-fuel condition to oxy-fuel condition. Furthermore, the effect of strain rate on flame structure of air-fuel and oxy-fuel condition increased greatly with hydrogen addition.

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