PAHs controlling soot nucleation in 0.101—0.811MPa ethylene counterflow diffusion flames
PAHs controlling soot nucleation in 0.101—0.811MPa ethylene counterflow diffusion flames
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DOI：
10.1016/j.combustflame.2021.01.015
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发表时间：
2021-05
影响因子：
4.4
通讯作者：
Kevin Gleason;F. Carbone;A. Gomez
中科院分区：
文献类型：
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作者：
Kevin Gleason;F. Carbone;A. Gomez
在大气压乙烯扩散火焰中，通过空间分辨测量多环芳烃（PAHs）浓度和碳烟量，研究了从母体燃料分子到多环芳烃（PAHs）和最终碳烟的转变过程。在此基础上，我们将焦点扩展到在0.101- 0.811MPa压力范围内具有自相似结构的扩散火焰。为此，我们补充高温测量的烟尘体积分数与光散射测量，一旦校正光束转向，产生烟尘颗粒的尺寸和数量浓度分布。一个化学模型，已被验证为所有物种的火焰中的一个在每个压力下的研究和4环的火焰在大气压下的3环芳烃，被用来比较配置文件的化学物种的烟灰量。进一步的分析得出了对烟灰数量成核率的评估以及与多环芳烃二聚率的比较。烟尘成核率是一致的，只有一个和两个环多环芳烃的二聚化，一个观察，确认在大气压火焰中的发现。压力和温度的变化对分子量越来越大的芳烃的浓度有越来越大的影响，甚至对烟灰体积分数和成核速率的影响也越来越大。压力从0.101 MPa增加到0.405 MPa增加了四倍，在具有恒定峰值温度的火焰中增加了烟灰成核速率和PAH二聚化速率，这主要是对双分子碰撞速率的浓度效应;在较高的压力范围（0.405-0.811 MPa）中观察到类似但不太明显的效应。压力和温度的变化对分子量增加的芳烃和烟灰的影响越来越大。
On the heels of a recent study in an atmospheric pressure ethylene diffusion flame in which the transition from parent fuel molecule to Polycyclic Aromatic Hydrocarbons (PAHs) and, eventually, soot was studied byspatially resolvedmeasurements of PAH concentrations and soot quantities, we extended the focus to diffusion flames with self- similar structure in the 0.101–0.811 MPa pressure range. To that end, we complemented pyrometry based measurements of soot volume fraction with light scattering measurements that, once corrected for beam steering, yielded soot particle size and number concentration profiles. A chemistry model, that had been validated for all species up to 3 ring aromatics in one of the flames investigated at each pressure and up to 4-rings for the flame at atmospheric pressure, was used to compare profiles of chemical species to those of soot quantities. Further analysis yielded the assessment of number nucleation rates of soot and their comparison to the dimerization rates of PAHs. Soot nucleation rate is consistent only with the dimerization of one- and two-ring PAHs, an observation that confirms findings in the atmospheric pressure flame. Changes in pressure and temperature have a progressively larger impact on the concentration of aromatics of increasingly larger molecular weight and, even more so, on soot volume fraction and nucleation rate. A four-fold increase in pressure from 0.101 MPa to 0.405 MPa increases the soot nucleation rate and PAH dimerization rate in flames with constant peak temperature, which is primarily a concentration effect on bimolecular collision rates; a similar but less pronounced effect is observed in the higher (0.405–0.811 MPa) pressure range. Changes in pressure and temperature tend to be progressively more consequential on aromatics of increasing molecular weight and soot.