射流搅拌反应器中氨/异辛烷的氧化特性研究  

Investigation on Oxidation Characteristics of Ammonia/Iso-Octane in Jet-Stirred Reactor

作　　者：卫海桥[1] 郭颖莹 潘家营[1] 张韧[1] 万思萌 Wei Haiqiao;Guo Yingying;Pan Jiaying;Zhang Ren;Wan Simeng(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学先进内燃动力全国重点实验室,天津300072

出　　处：《天津大学学报(自然科学与工程技术版)》2025年第4期379-386,共8页Journal of Tianjin University:Science and Technology

基　　金：国家自然科学基金资助项目(52222604,T2341001).

摘　　要：大分子烃类燃料普遍具有低温氧化特性,能够有效增强氨(NH3)反应活性.然而,目前关于氨/异构烷烃的氧化特性尚不清楚.本文基于射流搅拌反应器(JSR)和动力学分析方法,对纯氨、异辛烷(IC8H18)及其混合物的氧化特性进行了实验和数值模拟研究.实验工况选择500~1050 K温度范围,同时通过同步辐射真空紫外光电离质谱(SVUV-PIMS)和气相色谱技术(GC)对反应物和生成物进行浓度剖面的在线扫描,并使用改进的动力学机理对氨和异辛烷的氧化过程及其相互作用进行详细分析.研究结果表明,NH3和IC8H18的氧化活性在不同温度区间内存在相互促进与相互竞争并存的机制,从而在整体上表现为非单调的分段氧化特性.在820~1050 K温度条件下,IC8H18氧化(尤其是通过HO2路径)产生大量活性自由基,加强了链分支反应HO2+NO=NO2+OH,从而使得NH3的反应活性随着异辛烷的加入而提高;在500~820 K温度条件下,氨通过NOx反应路径促进羟基自由基的产生,使得IC8H18氧化温度降低、反应速率提高;在800~900 K温度区间内,随着反应温度增加,NH3的反应活性逐渐变强且争夺自由基能力提高,导致系统自由基池总量迅速减少,造成整体氧化反应活性降低,是导致分段氧化现象的主要原因.Large hydrocarbon fuels exhibit low-temperature oxidation properties,which can help enhance the reactivity of ammonia.However,the oxidation characteristics of ammonia/iso-paraffins remain unexplored.Herein,the oxidation characteristics of pure ammonia,iso-octane(IC8H18),and their mixtures were investigated in a jet-stirred reactor(JSR)using synchrotron vacuum ultraviolet photoionization mass spectrometry(SVUV-PIMS),gas chromatography(GC),and kinetics analysis at 500—1050 K.It was observed that depending on the reaction temperature,the ammonia and iso-octane reactivities could promote or compete with each other,and this behavior of segmented oxidation was manifested.Under the temperature condition of 820—1050 K,the oxidation of iso-octane,especially through the HO2 pathway,generated a large pool of reactive radicals,which strengthened the chain branching reaction HO2+NO=NO2+OH.This further resulted in an increase in the reactivity of ammonia with the addition of isooctane.Under the temperature condition of 500—820 K,ammonia facilitated the generation of hydroxyl radicals through the NOx reaction pathway,which resulted in decreasing oxidation temperature and increasing reaction rate of iso-octane.The oxidation temperature of iso-octane was decreased,and the reaction rate was increased.As the reaction temperature was increased within 800—900 K,the ammonia reactivity and its abilities to compete for the radicals were strengthened.This would lead to a rapid decrease in the total radicals,and as such,the overall oxidation reactivity was decreased,which explained the segmented oxidation behavior.

关 键 词：氨/异辛烷 射流搅拌反应器 氧化反应活性 反应动力学 氮氧化物 

分 类 号：TK46[动力工程及工程热物理—动力机械及工程]