EGR率对生物柴油调合燃料排放颗粒微观结构的影响分析

Effect of EGR Rate on Microstructure of PM Emitted from Biodiesel Blended Fuel

为深入探究燃料性质与燃烧环境改变对柴油机颗粒微观结构的影响,以不同EGR率条件下分别燃用柴油(B0)、生物柴油调合燃料(B50)的排放颗粒为研究对象,运用透射电镜测试技术结合分形理论,对颗粒基本碳粒子的微观结构参数、颗粒团聚体的形貌特征、团簇程度等进行测量与分析,结果表明,柴油中掺混生物柴油,导致基本碳粒子的层面间距、弯曲度减小,微晶尺寸略有增加;而引入EGR后,基本碳粒子的层面间距、弯曲度随EGR率的增加而增大,微晶尺寸逐渐减小。柴油中掺混生物柴油,颗粒间的团簇程度更加紧密;而EGR的引入会导致颗粒间的团簇程度减弱,使颗粒团聚体结构变得松散。

To further explore the influence of fuel properties and combustion environment on the Microstructure of PM for diesel engine,PM of diesel and biodiesel blended fuel under different EGR rates were studied.By using TEM technology,combined with fractal theory,the microstructure parameters of basic carbon particles,the morphology characteristics of particle aggregates and the degree of clusters were measured and analyzed.The results showed that when biodiesel was blended into diesel,the fringe separation distance and tortuosity of basic carbon particles decreased,and the fringe length increased slightly.However,with the increase of EGR rate,the fringe separation distance and tortuosity of basic carbon particles increased,and the fringe length decreased.When biodiesel was blended into diesel,the degree of clusters between PM was closer,while the introduction of EGR would weaken the degree of clusters between PM and made the structure of PM become looser.