本文以實驗觀察及理論預測等方法研究常壓環境之二氧化碳稀釋對低雷諾數富氧甲烷噴流擴散火焰結構與燃燒特性之影響。由於二氧化碳稀釋之富氧燃燒系統具有能提供排氣無氮氣與氮氧化物及高濃度二氧化碳氣體之特色，對於降低環境汙染以及高效率二氧化碳回收系統之設計有極佳之效果，但在二氧化碳稀釋之富氧噴流擴散火焰中，由於牽涉到稀釋量之操作，與過去傳統捲入空氣燃燒之操作方法有所差異，故本研究之主要目的在於探討其操作特性以及了解其火焰結構與行為。
在本文中利用實驗觀察火焰外型與長度隨稀釋量之變化情形，得到其火焰長度增長與稀釋量增加呈現指數關係式之結果，並整理歸納得到一廣用經驗式。同時亦利用量測火焰溫度分佈之情形，探討二氧化碳稀釋量對火焰整體熱結構與行為之影響。在火焰外形部分並無適合預測理論作比較，而火焰長度部分，僅有Roper的理論在火焰長度預測上最為接近，但儘管其預測結果遠優於其他預測理論，其結果仍有其些差異之處。本研究中亦利用實驗量測得到火焰不穩定定義出二氧化碳稀釋之富氧甲烷噴流擴散火焰之操作區間，並針對併流場(co-flowing)對火焰之影響作初步之討論。本研究乃針對二氧化碳稀釋之富氧甲烷噴流擴散火焰系統作初步之結論，所得之結論將可供後面陸續相關研究之探討。

In this study, the effects of co-flowing carbon dioxide dilution on the flame structure and characteristics of a low Reynolds number oxy-fuel methane jet diffusion flame are experimentally investigated. Carbon dioxide dilution of oxy-fuel combustion is characterized with no nitrogen (nor NOx) and high concentration of carbon dioxide in the exhaust gas which is of extreme importance to high efficiency CO2 sequestration and capturing as well as zero NOx pollutant emissions for the global issues of global warming and environment. The flame structure and behavior, and combustor operational characteristics are different for the carbon dioxide dilution oxy-fuel from the conventional air dilution diffusion flames. The objective of this study is to investigate the flame structure and operational characteristics of the carbon dioxide diluted oxy-fuel methane jet diffusion flame.
The variation of the flame outlook, shape and flame length with carbon dioxide dilution is first experimentally observed and found that the relation between the flame length and the dilution can be expressed in an general exponential form empirically. The thermal structure for the diluted oxy-fuel methane jet diffusion flame is also studied by using thermocouples. The various existing theoretical models for the diffusion flame shapes are also examined and found strong discrepancy. For the flame length, the predictions of the Roper’s model are found to best agree with experimental data. However, the deviation still exists. The operational range of the carbon dioxide diluted oxy-fuel methane jet diffusion flame is also defined based on experimental measurements of flame stability. In addition, the co-flowing effects are also studied and discussed. The results of the current studies of carbon dioxide diluted oxy-fuel methane jet diffusion flame will serve as the base for future in-depth studies of related combustion CO2 sequestration techniques.

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