二甲醚燃烧双火焰及排放特性

针对二甲醚与空气预混燃烧特性，利用在线光谱与色谱技术研究不同当量比对其燃烧的影响.二甲醚和空气预混气当量比小于1时，出现双火焰，利用光谱在线研究不同当量比时双火焰的发光情况；当量比大于1时，利用气相色谱法在线检测了尾气排放，检测到的非常规排放物除常见的甲醛和甲醇外，还检测到了乙醛，同时探讨了当量比对尾气中三种排放物浓度的影响.光谱结果表明，双火焰时上方火焰只有OH*发光和非常微弱的CH*发光，而下方火焰中有OH*、CH*以及C2*的发光谱带，且CH*和C2*的发光强度随当量比的减小而减弱.气相色谱结果表明，尾气中甲醇和乙醛的浓度随当量比减小而减小，甲醛排放量随当量比减小先增加后减小.
For combustion characteristics of dimethyl ether (DME)/air pre-mixture, the influence of different equivalence ratio on combustion was studied by on-line spectroscopy and chromatography. When the equivalence ratio was less than 1, double flames appeared, and the luminescence of double flames at different equivalence ratio was studied by on-line spectroscopy. When the equivalent ratio was greater than 1, gas chromatography was used to detect the exhaust emissions online, besides the common formaldehyde and methanol, acetaldehyde was also detected, and the influence of equivalent ratio on the concentration of above three exhaust emissions was also discussed. Spectroscopic results show that the upper flame has only OH* and very weak CH* emission, while the lower flame has OH*, CH* and C2* emission bands, and the emission intensity of CH* and C2*decreases with the decrease of equivalence ratio. The results of gas chromatography show that the concentration of methanol and acetaldehyde in tail gas decreases with the decrease of equivalent ratio, and the emission of formaldehyde increases firstly and then decreases with the decrease of equivalent ratio.