应用CHEMKIN化学动力学软件,构建乙醇/正庚烷的芳香烃(PAH)形成机理(包含241种组分,1703个基元反应).在激波管和预混火焰条件下,研究乙醇/正庚烷燃烧过程中前驱体单环芳香烃(苯)和多环芳香烃(萘、菲、芘)的形成,探讨乙醇掺混比对PAH形成的影响.对生成速率的分析结果表明,丙炔基的聚合与环化、苯基的加氢反应是形成苯的主要反应;多个苯环的形成主要通过脱氢加乙炔反应;具有氧化性的H和OH自由基减少了PAH的生成.敏感性分析结果表明,乙醇/正庚烷燃烧过程中,促进苯生成的主要反应是戊基、戊烯、烯丙基和丙基的分解.随着乙醇掺混比的增加,燃烧过程中分解形成的活性羟基(-0H)摩尔分数增加,PAH的生成速率下降,表明乙醇具有抑制PAH形成的作用.
The PAH formation mechanism of ethanol/n-heptane (including 241 species and 1 703 reactions)was built using the CHEMKIN software. The PAH (benzene, naphthalene, phenanthrene, pyrene) formation process of ethanol/n-heptane in shock tube and premixed flame was studied. The effect of ethanol ratios on PAH formation process was analyzed. The formation rate (ROP) analysis results showed that benzene was mainly formed by the polymerization of propargyl and the hydrogenation reaction of phenyl. Naphthalene, phenanthrene, and pyrene were mainly formed by H-abstraction acetylene addition. The H and OH oxidation radicals can reduce the formation of PAH. The sensitivity analysis results showed that during the combustion process of ethanol/n-heptane, the decomposition reaction of pentyl, pentenyl, allyl and propyl promoted the formation of benzene. During the decomposition, with the increase of ethanol ratios, the concentration of reactive --OH increased and the formation rate of PAH decreased. Study results showed that ethanol can reduce PAH formation.