EGR氛围参数对柴油机颗粒物氧化特性的影响

Effects of EGR Atmosphere Parameters on Particulate Oxidation Activity of Diesel Engine

针对柴油机EGR氛围产生的颗粒,采用热重分析法,考察了各颗粒样品的氧化失重过程,分析了EGR率、EGR废气组分、EGR温度等EGR氛围参数对颗粒氧化特性的影响,研究了不同氧化氛围、升温速率等氧化氛围参数对颗粒氧化过程的影响。结果表明,随着EGR率的升高,颗粒中SOF组分含量增加,炭烟组分含量减少,失重率峰值在低温失重区升高,在高温失重区降低,且对应的峰值温度均增加。相同EGR率时,随着EGR废气温度的升高,颗粒的氧化性能随着反应温度的提高而降低。EGR组分不同时,与废气、N2循环相比,在CO2循环下生成的颗粒失重速率更快,反应温度降低,颗粒更易氧化。随着升温速率的提高,颗粒的失重率峰值变化不大,颗粒的氧化反应出现滞后现象,特征点温度升高,颗粒的氧化性能随着升温速率的提高而降低。

The processes of oxidation and weight loss for the particles produced in EGR atmosphere of diesel engine were researched by using thermogravimetry and the effects of EGR rate,EGR exhaust gas component and EGR temperature on particulate oxidation activity were analyzed. The influences of oxidation atmosphere parameters such as different atmospheres and heating rates on particle oxidation process were investigated. The results showed that the content of SOF component increased,the soot content decreased,and the weight loss rate increased at low temperature weight loss area,decreased at high temperature weightlessness zone and its corresponding peak temperature increased with the increase of EGR rate. When the EGR rate was constant and the EGR exhaust gas temperature was increasing,the oxidation property of particle deteriorated with the increase of reaction temperature. When the EGR components were different,the particles produced in the CO2 cycle had faster weight loss rate,lower reaction temperature and easier oxidation property than those produced in exhaust or nitrogen cycle. With the increase of heating rate,the particle weight loss rate had little change,the oxidation reaction delayed and the characteristic point temperature increased. In addition,the oxidation property of particle deteriorated with the increase of heating rate.