燃烧火焰中核态碳烟颗粒粒度分布的在线检测研究

On-line Detection of Particle Size Distribution of Nuclei Soot in Flame

采用非侵入式无干扰针孔采样器与扫描型运动颗粒粒度分级仪(scanning mobility particle sizer,SMPS)相连接的方法,对乙烯/空气反扩散火焰中初始成核碳烟颗粒的粒度分布进行了在线检测。首先确定了SMPS的实时在线检测的实验研究过程,然后分析并讨论了碳烟采样稀释系统的稀释率计算方法。初步检测结果表明,在火焰底部粒径为3 nm的核态碳烟颗粒的数量大约在1012个/cm3以上,随着测量点位置增高,核态碳烟颗粒的数量减少,且粒径增大,碳烟粒度分布曲线逐渐向右移动,说明在火焰底部核态碳烟颗粒处于生长长大的状态。初始成核颗粒由于异相凝结和表面沉积而长大,同时伴随着核态碳烟颗粒之间较为剧烈的颗粒凝并和聚结现象。

On-line detection of nascent soot in ethylene/air inverse diffuse flame was conducted in terms of its particle size distribution （PSD） by use of a none-intrusive pin-hole sampler connected with a scanning mobility particle sizer （SMPS）. According to the preliminary result of the detection, the number of nuclei soot of size 3 nm at the lower part of flame was more than 1012/cm3, whereas the number of nuclei soot decreased at the upper part of the flame while the soot particles became bigger with PSD curves shifted to fight. The phenomena revealed that nuclei soot at lower part of the flame was in the growth state, and the nascent particles were growing due to the heterogeneous condensation and surface deposition, meanwhile, among the soot particles there existed violent coagulation and aggregation.