本文以實驗搭配數值模擬研究二氧化碳或氮氣稀釋氧氣為併流(co-flow)之富氧甲烷擴散火焰之燃燒特性。由於二氧化碳稀釋富氧甲烷燃燒系統可達到無氮燃燒，且可回收高濃度之二氧化碳做後續二氧化碳之高效率捕抓(capture)與有效封存(sequestration)，此燃燒系統所有燃燒後的氣體幾乎都可被回收，對於降低環境汙染與降低溫室效應有相當大的幫助。以純氧燃燒將造成相當高溫的火焰，所以實務尚需要回流部分含二氧化碳的煙道氣(flue gas)作為火焰降溫稀釋之用，但由於回流稀釋量太多會造成火燄不穩定，稀釋量太低氧氣濃度高卻容易造成局部高溫，對燃燒室設計相當不利，且高溫對於燃燒室材料選用會變得極為困難，成本也隨之提高。
由模擬結果得知，當甲烷擴散燃燒時，周圍的併流場會捲入燃料底部，造成部分預混的效果，使得火焰提早獲得氧氣而提前反應，火焰長度進而變短，當氧氣濃度提高時，燃燒速度變快，火焰變得更為短小，溫度也跟著提升，高溫時的二氧化碳Cp值為氮氣的1.67倍，高吸熱效果會使整體火焰溫度降低、火焰速度降低，反應變得比氮氣時更加延緩，OH量減少且有延後的情況發生，不完全的燃燒使得CO量變多。

In this paper, experiments with a numerical simulation of oxygen to carbon dioxide or nitrogen dilution and flow (co-flow) of the oxygen-enriched combustion characteristics of methane diffusion flame. Dilution of oxygen-enriched combustion of methane as carbon dioxide to nitrogen-free combustion system, and the high concentration of carbon dioxide recycled to do the follow-up of carbon dioxide efficient catch them (capture) and the effective storage (sequestration), the combustion system almost all the combustion gases can be be recycled, for reducing environmental pollution and reduce greenhouse there is a big help. To pure oxygen combustion will result in considerable heat in the flame, so still need to return part of the practice of carbon dioxide containing flue gas (flue gas) used as flame cooling diluted, but dilution of the amount returned will cause too much instability in the flame, the amount is too dilute Low oxygen concentrations are likely to cause high local temperature on the combustion chamber design of considerable disadvantage, and high-temperature materials used for the combustion chamber will become extremely difficult, cost will increase.
From the simulation results, when the diffusion combustion of methane, and the flow field around the bottom will get involved in the fuel, resulting in some of the effects of premixed, the flame of oxygen and the early response of early, flame length and then shortened, when the oxygen concentration increases, combustion speed becomes faster, the flame becomes more short, temperature increase with high temperature when the nitrogen dioxide Cp value of 1.67 times, the high endothermic effect will reduce overall flame temperature, flame speed reduces the reaction time becomes more than the nitrogen delay, OH reduced to happen and there is delayed, incomplete combustion of CO made more quantitative.

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