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

纳米级颗粒物质（Nano - pm）和多环芳烃（PANS）对人体健康有危害。为了减少纳米pm的排放，需要研究燃烧过程中PAHs形成行为的基本特征。本文采用激光诊断和气体采样的方法，研究了液体和气体燃料扩散火焰中的多环芳烃特征。实验燃料为甲烷（CH_4）、丙烷（C_3H_8）和己烷（C_6H_<14>）。采用激光诱导荧光（LIF）法测定了烟灰颗粒前体分子多环芳烃的空间分布。用激光诱导白炽灯（LII）法测定了烟尘的空间分布。从LIF和LIL的结果讨论了从多环芳烃到烟尘的过渡区域，并利用气相色谱（GC）测量了测试火焰中的多环芳烃浓度。比较了试验火焰中多环芳烃的浓度分布。结果表明，低碳燃料如丙烷和甲烷在下游部分燃料中被保留。这些燃料在下游部分变成了大量的多环芳烃。此外，还证实了在掠夺区存在相对较小的多环芳烃，如苯和甲苯，而在烟尘区没有观察到较大的多环芳烃，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.