当量比对正庚烷预混燃烧下多环芳烃生成影响

Effect of equivalence ratio on polycyclic aromatic hydrocarbons formation in premixed n-heptane combustion

采用107种组分和542个基元反应的化学反应机理,数值模拟正庚烷预混燃烧下多环芳烃的生成.计算分析正庚烷预混燃烧下主要反应物(O2和n-C7H16)、反应生成物(CO、CO2和多环芳烃)和中间产物(CH4、C2H4和C3H6)的分布,并与测量结果进行对比.分析燃烧当量比对多环芳烃生成规律、苯与联苯生成速率及苯生成关键反应基元步敏感性的影响.结果发现,主要反应物、反应生成物及部分中间产物分布规律的计算结果与实测结果吻合,说明该机理可用于正庚烷预混燃烧下产物预测,随燃烧当量比增加,苯、联苯、菲和芘的体积分数升高,苯与联苯的总生成速率显著提高.

Polycyclic aromatic hydrocarbons（PAHs） formation in premixed n-heptane combustion was simulated using a detailed mechanism including 107 species and 542 elementary reactions. The species concentration distri- butions were analyzed numerically, with the species including the main reactants （02 and n-CTHI6 ）, main products（CO and CO2）, intermediate products（CH4, C2H4 and C3H6）, and PAHs. The computational results were compared with the experiment data. The effect of combustion equivalence ratio on PAHs formation, the for- mation speed of benzene（ A1 ） and naphthalene（A2 ）, and the sensitivity to the key reaction of Al formation were analyzed as well. The results show that the computational results for the species concentration distributions of the main reactants, main products and intermediate products agree with the experiment data. The model can be used to predict reaction products in premixed n-heptane combustion. Furthermore, with the combustion equivalence ratio increasing, the mole fractions of A1 , A2, phenanthrene（ A3 ） , and pyrene（ A4 ） are improved. The total for- mation speeds of Al and A2 are also improved.