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在新一代轿车用共轨柴油机上对生物柴油及柴油燃烧排放的颗粒粒径分布和纳米颗粒的生成机理进行了研究.试验结果表明,柴油机的颗粒粒径分布为双态分布:核态和聚集态,基本以50nm为分界线.在2000r/min,50N·m工况下,颗粒粒径分布为单一的聚集态分布,当转矩超过100N·m后,颗粒粒径分布从单态转化为双态分布.对于本试验中的生物柴油混合燃料,当燃料混合比小于60%,发动机高负荷下其粒径分布也为双态,相同条件纯生物柴油的颗粒粒径分布仅为单一聚集态.低负荷时,对比所有燃料的颗粒粒径分布都为单一聚集态.生物柴油混合燃料可以明显降低柴油机的聚集态颗粒数量浓度.而颗粒中核态纳米颗粒的形成可解释为随着负荷的增大,燃料的耗油量和排气温度的上升,燃烧生成的SO2被氧化催化器转化为SO3,其水化物硫酸的形成促成了核态纳米颗粒的形成.所以生物柴油混合燃料的硫含量决定带有氧化催化器的轻型柴油机的纳米颗粒的形成和数量.
The particle size distribution and nanoparticle formation mechanism of biodiesel and diesel combustion on a common-rail diesel engine for a new generation passenger car were studied.The experimental results show that the particle size distribution of diesel engine is bimodal distribution: nuclear state and aggregation State, the basic 50nm as the dividing line at 2000r / min, 50N · m conditions, the particle size distribution of a single aggregate distribution, when the torque exceeds 100N · m, the particle size distribution from single to Bimodal distribution.For the biodiesel fuel mixture in this experiment, when the fuel mixture ratio is less than 60%, the particle size distribution is also bimodal at high engine load, and the particle size distribution of pure biodiesel under the same conditions is only a single aggregation state At low load, the particle size distribution of all the fuels compared to a single aggregation state. Biodiesel blend fuels can significantly reduce the concentration of diesel particulate matter concentration. The formation of particles in the nucleation state nanoparticles can be interpreted as the load increased Large, fuel consumption and exhaust temperature rise, the combustion of the generated SO2 by the oxidation catalyst into SO3, the formation of hydrated sulfuric acid contributed to the formation of nuclear-state nano-particles. So biodiesel Sulfur content of fuel determined engagement formation and the number of nanoparticles with a light-duty diesel oxidation catalyst.