正庚烷对冲扩散火焰中添加长链醚类对碳烟前体生成特性的影响  

The effects of adding long-chain ethers in n-heptane counterflow diffusion flames on the formation characteristics of soot precursors

作　　者：包嘉靖 别洪飞 王子威 肖睿[1] 刘冬[2] 吴石亮 BAO Jiajing;BIE Hongfei;WANG Ziwei;XIAO Rui;LIU Dong;WU Shiliang(Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education,School of Energy and Environment,Southeast University,Nanjing 210096,Jiangsu,China;Advanced Combustion Laboratory,School of Energy and Power Engineering,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China)

机构地区：[1]东南大学能源与环境学院教育部能源热转换与控制重点实验室,江苏南京210096 [2]南京理工大学能源与动力工程学院先进燃烧实验室,江苏南京210094

出　　处：《化工学报》2023年第4期1680-1692,共13页CIESC Journal

基　　金：江苏省基础研究计划青年基金项目(BK20190363);国家自然科学基金青年科学基金项目(51906043)。

摘　　要：生物质基长链含氧燃料具有良好的碳烟减排特性,是富有前景的柴油添加剂。通过实验和数值模拟分析了25%三丙二醇单甲醚(TPGME)和25%聚甲氧基二甲醚(PODE)添加对正庚烷对冲扩散火焰中碳烟前体生成特性的影响。通过气相色谱(GC)测量了对冲扩散火焰中C1~C4烃类的摩尔分数,实验结果表明TPGME和PODE的添加减少了乙烯和乙炔的形成。通过反应动力学机理结合解耦方法实现了燃烧动力学过程模拟,能够很好匹配实验结果。模拟结果表明核心燃烧区域的温差不超过50 K,说明含氧添加剂对火焰温度影响较小;稀释效应和热效应降低了乙炔、乙烯的浓度,而化学效应则有利于乙烯和乙炔的生成。生产率(ROP)和反应路径计算表明不饱和烃主要由正庚烷的氢提取和β-断键反应生成,两种添加剂均不会对该路径产生实质性影响。由于氧原子的存在,TPGME和PODE分子中碳原子极易转化为醛和一氧化碳(CO)而非不饱和烃。最终,稀释效应和热效应是降低正庚烷火焰中碳烟前体排放的关键因素。Biomass-derived long-chain oxygenated fuels have good soot emission reduction properties and are promising diesel additives.In this work,the effects of 25%tripropylene glycol methyl ether(TPGME)and 25%polyoxymethylene dimethyl ether(PODE)additions on the soot precursor formation characteristics in n-heptane counterflow diffusion flames were experimentally and numerically analysed.The mole fractions of C1—C4 hydrocarbons in counterflow diffusion flames were measured by gas chromatography(GC).The experiments showed that the additions of TPGME and PODE suppressed the formation of ethylene and acetylene.The numerical simulations were performed through a reaction kinetic mechanism combined with the decoupling strategy,which could well capture the experimental observations.The simulations showed that the temperature differences in the key combustion zone were not more than 50 K,indicating that the oxygenated additives had little effects on the flame temperature.The dilution effect and thermal effect reduced the concentration of acetylene and ethylene,while chemical effect was beneficial to the formation of acetylene and ethylene.The rate of production(ROP)and reaction pathway analyses illustrated that unsaturated hydrocarbons were mainly generated via hydrogen abstraction andβ-scission of n-heptane,and neither of the two additives had a remarkable impact on the pathways.Due to the presence of oxygen atoms,the carbon atoms on TPGME and PODE molecules trended to be converted into aldehydes and carbon monoxide(CO)instead of unsaturated hydrocarbons.Ultimately,the dilution effect and thermal effect played dominant roles in reducing the soot precursor emissions of n-heptane flame.

关 键 词：含氧添加剂 碳烟前体 对冲火焰 生物油 动力学机理 

分 类 号：TK6[动力工程及工程热物理—生物能]