激光消光法测量甲苯高温裂解的碳烟产率

建立了碳氢燃料在反射激波作用下高温裂解碳烟生成的检测系统,利用激光消光法测量了甲苯/氩气在高温条件下裂解生成碳烟的产率。实验条件:甲苯摩尔浓度0.25%和0.5%,压力约2和4atm,温度1 630~2 273K。获得了碳烟产率随温度、压力和燃料浓度的变化规律。碳烟产率随温度变化呈高斯分布,随着压力或浓度的增大,碳烟产率增大,碳烟产率最大达55%。产率的峰值温度随压力变化不大,但甲苯摩尔浓度从0.25%增大到0.5%时,峰值温度从1 852变为1 921K。对比了压力为4atm,燃料摩尔浓度为0.5%的甲基环己烷和甲苯的碳烟产率,甲基环己烷裂解碳烟产率峰值对应的温度为2 045K,比甲苯约高135K,但其最大碳烟产率仅有甲苯的1/8。结果为研究发动机内碳烟颗粒物排放及碳烟形成机理提供了实验依据。

Measurement of Soot Yield from the Pyrolysis of Toluene at High Temperatures by Laser Extinction Method

The measurement system for the detection of soot production as high-temperature pyrolysis of hydrocarbon fuels be-hind the reflected shock wave was established.By using the laser extinction method,the soot yields of toluene/argon mixtures were measured at high temperatures.The mole fractions of toluene were 0.25% and 0.5% while the pressures were approximate 2 and 4 atm.The temperatures ranged from 1 630 to 2 273 K.The dependence of soot yield on the temperature,pressure and fu-el concentration was obtained.With the changes of temperature,the soot yield is a Gauss distribution.The soot yield increases as the pressure or fuel concentration increases.The maximum of soot yield was as high as 5 5%.The peak temperature of soot yield was not changed dramatically with the pressure.However,it changed from 1 852 to 1 921 K as the concentration of toluene increase from 0.25% to 0.5%.Moreover,we compared the soot yield between toluene and methylcyclohexane at pressure of 4 atm with fuel concertation of 0.5%.During the pyrolysis of methylcyclohexane,the peak temperature of soot yield was 2 045 K,which is about 135 K higher than that of toluene.However,the maximum soot yield of methylcyclohexane is only 1/8 of tol-uene.This work provides experimental reference for the research of soot particle emission in the engines and the mechanism of soot formation.