正丁烷燃料中低温氧化的骨架反应机理

A Skeletal Mechanism for Low-to-Mediate Temperature Oxidation of n-Butane

本文基于Healy等人建立的正丁烷详细反应机理(230个组分,1328个反应),采用直接关系图法,反应路径分析以及敏感性分析相结合的方法,构建了一个包含83个组分,397个反应的中低温反应动力学骨架模型。路径分析发现,在低温反应中,正丁烷氧化着火主要受链传播反应中的放热循环控制。而在中温反应中,正丁烷及其下游产物正丁基的裂解反应变得重要,大分子裂解后的小分子氧化加快反应进程。本文骨架模型在温度范围550~1050 K、压力范围0.1~3MPa、当量比范围0.5~2.0条件下对着火延迟时间、层流火焰速度、温度以及重要组分浓度分布的预测均与详细机理保持很好的一致性,同时与文献中快压机、定容燃烧弹和搅拌射流反应器的实验结果也吻合较好。

Based on the detailed reaction mechanism of n-butane(230 species and 1328 reactions)established by Healy et al.,a skeletal chemical kinetics model for low-to-mediate temperature oxidation of n-butane including 83 species and 397 reactions was derived using an integrated reduction method that contains directed relation graph method,reaction path analysis,and sensitivity analysis.The reaction path analysis showed that the dominant factor for ignition was the exothermic cycle in chain propagation paths during the low-temperature reaction.However,for the mediate-temperature reaction,the cracking reactions of n-butane and its downstream product n-butyl started to become important,and the oxidation of small molecules decomposed from large molecules could accelerate the ignition process.The skeletal mechanism exhibited a high accuracy for low-to-mediate temperature(550~1050 K) in predicting oxidization characteristics parameters over a wide range of pressures(0.1~3 MPa) and equivalence ratios(0.5~2.0),such as ignition delay times,laminar flame speeds,distribution of temperatures,and the detailed profiles of main species concentrations.In addition,the skeletal mechanism was validated well against the experimental data in rapid compression machines,constant volume combustion bombs,and stirred jet reactors.Although the size of the skeletal mechanism was greatly reduced,the mechanism could reflect the low-to-mediate oxidation characteristics of n-butane.