Effects of CO_2 Dilution on Methane Ignition in Moderate or Intense Low-oxygen Dilution(MILD) Combustion:A Numerical Study  

CO_2稀释对甲烷高温低氧条件下自燃着火特性影响的数值模拟(英文)

作　　者：曹甄俊 朱彤 

机构地区：[1]College of Mechanical Engineering,Tongji University [2]Shanghai DFYH Tech Services Co.,Ltd.

出　　处：《Chinese Journal of Chemical Engineering》2012年第4期701-709,共9页中国化学工程学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China (50206014);the Shuguang Scholar Program of Shanghai Education Development Foundation (05SG23)

摘　　要：Homogeneous mixtures of CH4/air under moderate or intense low-oxygen dilution（MILD） combustion conditions were numerically studied to clarify the fundamental effects of exhaust gas recirculation（EGR）,espe-cially CO2 in EGR gases,on ignition characteristics.Specifically,effects of CO2 addition on autoignition delay time were emphasized at temperature between 1200 K and 1600 K for a wide range of the lean-to-rich equivalence ratio（0.2~2）.The results showed that the ignition delay time increased with equivalence ratio or CO2 dilution ratio.Fur-thermore,ignition delay time was seen to be exponentially related with the reciprocal of initial temperature.Special concern was given to the chemical effects of CO2 on the ignition delay time.The enhancement of ignition delay time with CO2 addition can be mainly ascribed to the decrease of H,O and OH radicals.The predictions of tem-perature profiles and mole fractions of CO and CO2 were strongly related to the chemical effects of CO2.A single ignition time correlation was obtained in form of Arrhenius-type for the entire range of conditions as a function of temperature,CH4 mole fraction and O2 mole fraction.This correlation could successfully capture the complex be-haviors of ignition of CH4/air/CO2 mixture.The results can be applied to MILD combustion as ＂reference time＂,for example,to predict ignition delay time in turbulent reacting flow.在中等或强烈的低氧的冲淡下面的 CH4/air 的同类的混合物(温和) 燃烧条件数字地被学习澄清基本效果用尽煤气的再通行(EGR ) ，特别在 EGR 气体的 CO2，在点火特征上。明确地，在自动点火延期时间的 CO2 增加的效果在在 1200 K 和 1600 K 之间的温度被强调为大量 lean-to-rich 等价比率(0.22 ) 。结果证明点火延期时间与等价比率或 CO2 冲淡比率增加了。而且，点火延期时间被看见指数地相关与起始的温度相互。特殊担心在点火延期时间被给 CO2 的化学效果。有 CO2 增加的点火延期时间的改进能主要被归功于到 H 的减少， O 并且哦激进分子。温度侧面的预言和公司和 CO2 的鼹鼠部分是强烈与 CO2 的化学效果有关。单个点火时间关联被获得处于良好的竟技状态为条件的全部范围的 Arrhenius 类型作为温度， CH4 鼹鼠部分和 O2 鼹鼠的功能部分。这关联能成功地捕获 CH4/air/CO2 混合的点火的复杂行为。例如，结果能作为参考时间被用于温和燃烧在狂暴的反应流动预言点火延期时间。

关 键 词：moderate or intense low-oxygen dilution combustion ignition delay time autoignition METHANE 

分 类 号：X928.7[环境科学与工程—安全科学]