柴油机燃烧生成芳香烃、碳烟及NO_x的化学动力学研究

Study on Aromatic Hydrocarbons,Soot and NO_x Formed in Diesel Engine Combustion Using Detailed Chemical Kinetics

在LLNL详细正庚烷氧化反应模型基础上,将苯(A1)和多环芳香烃(A2、A3、A4)的详细反应机理和NOx的生成机理加入其中形成了一个包含芳香烃和NOx的正庚烷氧化反应组合模型,并通过激波管试验验证了该组合模型。在CHEMKIN软件上运用该组合模型对柴油机燃烧反应产物中的芳香烃、碳烟和NOx进行了研究,结果表明:芳香烃的生成在Ф-T图中都呈钟形分布,随着环数的增加它们所对应的生成温度大致呈逐渐升高的趋势。利用芳香烃-Ф-T图可以较准确地预测碳烟-Ф-T图,再结合NOx-Ф-T图可以绘制出芳香烃-碳烟-NOx-Ф-T图,结果表明:芳香烃和碳烟在1 150～2 200K、当量比大于2的范围内大量生成,NOx在温度高于2 350K、当量比小于1.2的范围内大量生成。

Based on the LLNL detailed heptane oxidation model, benzene （A1）, polycyclic aromatic hydrocarbons （A2, A3, A4） detailed reaction mechanism and NO, formation mechanism were added to form a combination model. Verified by shock tube experiments, the combination model was used to study aromatic hydrocarbons, soot and NOx in diesel engine combustion products based on CHEMKIN software. The results indicate that the generation of aromatic hydrocarbons in the Ф-T map shows ＂bell shape＂ distribution and with the ring number increase its formation temperature rises gradually. The aromatic hydrocarbons-Ф -T map can accurately predict soot-Ф-T may, further plot the aromatic hydrocarbons-soot-NOx-Ф-T map combined with NOx-Ф-T map. Aromatic hydrocarbons and soot generate largely at 1 150- 2 200 K and equivalence ratio greater than 2, and at temperatures higher than 2 350 K and equivalence ratio less than 1.2 NO, generates largely.