Study on a laser probe measurement for precursors of nano-PM generated in combustion fields

纳米颗粒物(Nanum-PM)和多环芳烃(PAN)对人体健康有一定的危害。研究燃烧过程中多环芳烃生成行为的基本特征是减少纳米颗粒物排放的关键。本研究采用激光诊断法和气体采样法研究了液体燃料和气体燃料扩散火焰中多环芳烃的特征。试验燃料为甲烷(CH4)、丙烷(C3H8)和己烷(C6H&lt；14&gt；)。利用激光诱导荧光(LIF)方法获得了碳烟颗粒前驱体分子多环芳烃的空间分布。用激光诱导白炽法(LII)测量了碳烟的空间分布。根据LIF和LIL的结果，进一步讨论了多环芳烃向碳烟的转变区域，并用气相色谱(GC)测定了试验火焰中的多环芳烃浓度。对实验火焰的多环芳烃浓度分布进行了比较。结果表明，丙烷、甲烷等低碳数燃料残留在下游部分燃料中。而且，这些燃料在下游部分被转化为大分子多环芳烃。此外，还证实了洗刷区存在苯和甲苯等较小的多环芳烃物种，而在煤烟区没有观察到较大的多环芳烃物种，如氟和芘。

Nano meter size particulate matter (nano-PM) and polycyclic aromatic hydrocarbons (PANS) have harmful effects for human health. Investigations of fundamental characteristic of formation behavior of PAHs in combustion process were required for the reduction of nano-PM emission. In this study, PAHs characteristics in diffusion flames of liquid and gas fuels were investigated using laser diagnostic and gas sampling methods. Methane (CH_4), propane (C_3H_8) and hexane (C_6H_<14>) were used as the test fuels. A laser induced fluorescence (LIF) method was used to obtain the spatial distributions of PAHs, which were precursor molecules of soot particles. Spatial distributions of soot were also measured by a laser induced incandescence (LII) method. A transition region from PAHS to soot was discussed from the results of LIF and LIL Further, PAH concentrations in the test flames were measured using a gas chromatography (GC). Profiles of PAHs concentrations of test flames were compared. As the results, it was found that the low carbon number fuels such as propane and methane are remained to some fuel at downstream part. And, these some fuels were changed to large PAHs at downstream part. Moreover, it was confirmed that relatively small PAHs species such as benzene and toluene existed in looting region, however, the larger PAHs such as fluorine and pyrene could not be observed in the sooting region.