分析了生物柴油多环芳香烃(PAHs)的形成机理,以及C3自由基、乙炔、OH/O自由基等对PAHs的生成和长大的影响.重新构筑了包含PAHs形成过程的MDP机理,通过与实验数据的比较,验证了MDP机理的有效性.考察了生物柴油芳香烃燃烧产物随当量比、燃烧温度的变化规律,计算了生物柴油燃烧过程中每个基元反应的ROP系数,总结了多环芳香烃苯、萘、菲、芘的主要形成路径.结果表明,生物柴油燃烧过程中,小分子C2、C3自由基首先形成第1个苯环,苯环再经过HACA反应和环化反应形成多环芳香烃;生物柴油第1个苯环不仅可以通过C3H3聚合反应形成,还可以通过C4H5与乙炔加成反应形成.
The PAHs formation mechanism of biodiesel fuel was analyzed, and the impacts of C3 radical, acetylene, OH/O radicals on the formation process of PAHs were studied. The new methyl decanoate oxidation coupling mechanism which includes the formation of PAHs was re-built, and the validity of MDP mechanism was verified through the comparison with the experimental data. The ROP coefficient of each elementary reaction was calculated in the shock tube combustion conditions, and the major formation path of PAHs (benzene, naphthalene, phenanthrene and pyrene) was summarized. The results showed that the first benzene ring was formed by C2, C3 radi- cals in the combustion process, and then polycyclic aromatic hydrocarbons were formed through the HACA reaction and cyclization reaction. The first benzene ring of biodiesel was formed not only by the polymerization of C3H3 but also through the addition reaction between C4H5 and acetylene.