柴油/甲烷和柴油/甲醇二元燃料着火反应机理比较研究  

Comparison of Ignition Reaction Mechanism of Diesel/Methane and Diesel/Methanol Dual Fuel

作　　者：姚春德[1] 胡江涛[1] 臧儒振[1] 银增辉[1] 耿培林[1] 

机构地区：[1]天津大学内燃机燃烧学国家重点实验室,天津300072

出　　处：《工程热物理学报》2017年第2期392-398,共7页Journal of Engineering Thermophysics

基　　金：国家自然科学基金重点项目(No.51336005)

摘　　要：本文在定容燃烧弹中利用高速摄像技术研究了柴油在甲烷/空气和甲醇/空气氛围中低温着火特性,并基于正庚烷/甲烷简化机理和正庚烷/甲醇骨架机理,对比分析了两种二元燃料的低温氧化路径。试验和模拟结果均表明甲烷和甲醇都能使柴油着火时刻推迟,且甲醇推迟作用更明显,柴油推迟着火现象随甲烷和甲醇当量比增大而更明显,随环境温度升高而减弱。反应路径分析表明,甲烷和甲醇的脱氢反应消耗了大量OH抑制了正庚烷着火,甲醇抑制作用强于甲烷原因在于甲醇消耗OH速率快,且只通过低温下很稳定的H_2O_2分解向自由基池中提供OH,而甲烷消耗的OH少,还能通过链传递反应(CH_3+HO_2=CH_3O+OH)贡献相当数量的OH。The ignition characteristics of diesel in premixed methane-air and methanol-air mixture atmospheres（MeAA and MoAA） at low temperature were studied respectively in a constant volume combustion chamber equipped with a high-speed camera.Using the reduced reaction mechanism of n-heptane/methane fuel blends and the skeletal reaction mechanism of n-heptane/methanol fuel blends respectively,the oxidation processes at low temperature of these dual fuels were studied by Chemkin-Pro.Results show that,in MeAA and MoAA,ignition delays of diesel become longer;flame lift-off lengths get longer;and flame natural luminosity become weaker.These trends in MoAA are more noticeable than those in MeAA,and these phenomena become more significant with equivalent ratios of methane and methanol increase and initial temperature decrease.Analyses of reaction paths show that,OH is consumed in large quantities by dehydrogenation of methane and methanol,which leads to the activity of the whole reaction system reduced.So ignition delays of n-heptane are prolonged.The rate of methanol dehydrogenation is more quick than methane,so the consumption rate of OH by methanol is also more quick.While the production of OH is only through the decomposition of H_2O_2,which is stable at low temperature,in methanol oxidation process.However,methane dehydrogenation consumes less OH than methanol,and reaction CH_3＋ HO_2= CH_3O ＋OH in methane oxidation process can provide abundant OH to the radical pool.All these factors result in the inhibition for n-heptane ignition by methanol is stronger than methane.

关 键 词：柴油 甲烷 甲醇 滞燃期 着火特性 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]