生物柴油调合燃料在EGR氛围下的燃烧颗粒结构特征分析

Analysis on the structural characteristics of combustion particles of biodiesel blended fuel in EGR atmosphere

以某农用单缸柴油机为研究对象,在EGR率分别为0,15%,30%的条件下,测试其燃用生物柴油调合燃料时的碳烟排放特性,探究EGR率对生物柴油调合燃料燃烧颗粒结构特征的影响。研究结果表明:生物柴油调合燃料可以缓解因引入EGR而导致的碳烟排放量升高问题,且大EGR率工况下的改善效果更显著;柴油机排放颗粒物的粒径为20~80 nm,呈正态分布;相同EGR率条件下,燃用生物柴油调合燃料形成的颗粒粒径明显减小,且颗粒间的团聚程度增强,颗粒的孔隙率增大,界面层厚度增加;采用EGR技术,颗粒群的平均粒径增大,团聚程度增强,颗粒的孔隙率减小,界面层厚度增加;掺混生物柴油及引入EGR均会导致形成的颗粒表面粗糙程度和不规则程度有所提高。

Taking an agricultural single cylinder diesel engine as the research object,the soot emission characteristics of biodiesel blended fuel were tested under the conditions of EGR rates of 0,15%and 30%,and the influence of EGR rate on the combustion particle structure characteristics of biodiesel blended fuel was explored.The results indicate that biodiesel blended fuel can alleviate the problem of increased soot emissions caused by the introduction of EGR,and the improvement effect is more significant under high EGR rate conditions.The diesel engine exhaust particle size range is mainly between 20 nm and 80 nm,mainly showing normal distribution.Under the same EGR rate conditions,the particle size formed by burning biodiesel blended fuel significantly decreases,and the degree of agglomeration between particles increases,the porosity of particles increases,and the thickness of the interface layer increases.By adopting ECR technology,the average particle size of the particle group increases,the degree of agglomeration increases,the porosity of the particles decreases,and the thickness of the interface layer increases.Mixing biodiesel and introducing EGR can both increase the roughness and irregularity of the formed particles.