小分子含氧燃料对正庚烷燃烧碳烟前驱物的影响

摘要

为了探讨含氧燃料/正庚烷燃烧过程中芳香烃(PAH)的形成过程,深入理解含氧燃料对柴油机颗粒形成的影响,采用化学动力学软件构建了含氧燃料/正庚烷/PAH着火燃烧模型.在类似柴油机燃烧的条件下,研究添加小分子含氧燃料二甲醚、甲醇和乙醇对正庚烷燃烧过程中碳烟前驱物芳香烃的影响.研究结果表明:随着燃料中氧含量的增加,不完全燃烧中间产物C2H2、C2H4含量和芳香烃含量逐渐降低;二甲醚和乙醇的含氧量相同,但由于其分子结构中氧原子位置的不同,导致燃料碳的迁移路径不同,最终使得二甲醚降低PAH的能力强于乙醇;虽然甲醇、乙醇有相同的含氧官能团,但得益于甲醇分子没有C-C结构,使得甲醇降低PAH的能力要强于乙醇.%An oxygenous fuel-heptane/PAH ignition combustion model was built with chemical kinetic software in order to investigate the polycyclic aromatic hydrocarbon (PAH) formation during the oxygenous fuel-heptane combustion process and deeply understand the effect of oxygenated fuel on the formation of diesel soot.Under the condition of similar diesel engine,the study on the effects of adding small-molecule oxygenous fuel such as DME,methanol and ethanol into n-heptane on soot precursor-aromatics was carried out.The research results showed that with an increase of oxygen content in fuel,the concentrations of incomplete combustion intermediate products such as C2 H2,C2 H4 and aromatics are decreased.Although DME has the same oxygen content as ethanol,there are different fuel carbon reaction paths between these two fuels due to the different position of oxygen atom in the molecular structure.Therefore,DME has greater effectiveness on PAH evolution than ethanol.Although methanol has the same oxygen functional group as ethanol,methanol has greater effectiveness on PAH evolution than ethanol because methanol molecules do not have C-C structure.