乙炔火焰中添加H_2O/CO_2对碳烟颗粒尺寸分布的影响

Effects of H_2O/CO_2Addition to Acetylene Flame on Soot Particle Size Distribution

基于颗粒群平衡理论,构建一维层流预混火焰中碳烟颗粒动力学演化过程的数学模型.该模型包含了颗粒的成核、凝并、表面生长和氧化等过程,采用Monte Carlo随机算法进行求解.结合详细的化学反应机理,搭建了求解碳烟颗粒尺寸分布的计算平台.分析了乙炔层流预混火焰中添加二氧化碳和水两种组分时对碳烟生成的影响,获得了0%、20%和40%3组不同添加比例下的碳烟尺寸分布.结果表明,在当量比为2.5且保持不变的情况下,添加二氧化碳和水能够有效降低碳烟的生成,其中添加40%水时对碳烟的抑制效果更加明显;同时,二氧化碳和水的添加使得大粒径碳烟颗粒数量降低.

In this paper,first,a mathematical model based on the particle population balance theory,which takes into consideration the nucleation,coagulation,surface growth and oxidation of particles,is established to describe the dynamic evolution of soot particles in one-dimension laminar premixed flames.Next,the model is solved by means of Monte Carlo stochastic method.Then,based on a detailed chemical kinetic mechanism,a computation platform of particle size distribution is established.With this platform,the effects of CO_2 and H_2O addition on the soot formation in laminar acetylene / air premixed flames are analyzed,and the particle size distribution affected by the CO_2/ H_2 O dosage( 0%,20% and 40%) is obtained8.The results show that the addition of CO_2 and H_2O slows down the soot formation when the equivalence ratio remains unchanged at 2.5,especially at a H_2 O addition of 40%;and that fewer particles in large size may form due to the addition of CO_2 and H_2O.