摘要
基于正庚烷层流扩散火焰系统以及热泳取样和探针取样系统,结合透射电子显微镜和热重分析技术,研究了甲烷掺混对碳烟颗粒的微观形貌、纳观结构和氧化活性的影响.研究结果表明,随着甲烷添加比例增大,碳烟的分形维数和平均基本粒子直径减小,表明碳烟颗粒的团聚程度下降,且生长受到抑制.此外,随甲烷添加比例增大,碳烟颗粒的微晶片层尺寸减小,曲率和层间距增大,表明碳烟颗粒的纳观结构有序度降低.另一方面,随着甲烷掺混比例从0增加到30%,碳烟样品的表观活化能减少了19.5 kJ/mol,氧化反应特征温度下降了20℃左右,表明氧化反应活性提高.氧化活性的升高与碳烟颗粒纳观结构有序度的下降和分形维数减小有关.
The effects of methane addition on the morphology,nanostructure and oxidation reactivity of in-flame soot particles were investigated based on the n-heptane laminar diffusion flame.The soot samples in the flame were obtained using the thermophoretic sampling and probe sampling systems,with the combination of field emission transmission electron microscopy and thermogravimetric analysis techniques.Experimental results show that the fractal dimension of soot aggregates and the mean size of primary particles decrease in response to the increase in methane addition ratio,suggesting a decrease in the agglomeration degree of soot particles and an abatement of soot growth.Furthermore,with the increase in methane addition ratio,the soot particles exhibit a decrease in fringe length and an increase in separation distance and tortuosity.As a consequence,the soot nanostructure becomes less ordered.On the other hand,with the increase of methane addition ratio from 0 to 30%,the apparent activation energy of soot sample decreases by 19.5 kJ/mol,and the characteristic temperature of oxidation reaction decreases by about 20℃respectively,which means an increase in the oxidation reactivity of soot.The decrease of nanostructure order degree and fractal dimension of soot particles contributes to the increase in oxidation reactivity.
作者
王庚源
张伟
李云强
吕刚
宋崇林
Wang Gengyuan;Zhang Wei;Li Yunqiang;LüGang;Song Chonglin(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)
出处
《燃烧科学与技术》
CAS
CSCD
北大核心
2024年第2期128-136,共9页
Journal of Combustion Science and Technology
基金
国家自然科学基金资助项目(51876142).
关键词
扩散火焰
正庚烷
甲烷
碳烟结构
氧化活性
diffusion flame
n-heptane
methane
soot structure
oxidation reactivity
