【摘要】 研究了6114柴油机不同工况下排气颗粒的数浓度、体积浓度和粒径分布特征,测试工况下柴油机排气颗粒数浓度均呈包括核模态(峰值粒径为10 nm~20 nm)和积聚模态(峰值粒径为50 nm~80 nm)的双峰对数正态分布。高转速下排气颗粒数浓度和体积浓度大于中间转速时的数浓度和体积浓度。相同转速下,颗粒体积浓度随负荷增加而增大,而数浓度高转速下随负荷增大而增加,中间转速下随负荷增加没有规律性变化。相同转速下,积聚模态数浓度随负荷增加而增大,核模态数浓度高转速下随负荷增大而增加,但在中间转速下随负荷增加无规律性变化。相同转速下,随负荷增加,核模态峰值粒径有减小趋势。中间转速下积聚模态峰值粒径随负荷增大先增大后减小,高转速下积聚模态峰值随负荷变化无明显变化。中间转速下排气颗粒的核模态峰值粒径小于高转速下核模态的峰值粒径,积聚模态峰值粒径大于高转速下积聚模态的峰值粒径。排气颗粒中核模态粒子占有较大的数量百分比,积聚模态粒子占有较大的体积百分比。更多还原

【Abstract】 Exhaust particle number weighted and volume weighted concentrations and size distribution were measured in a 6114-model diesel engine by a two-stage dilution system and an SMPS.The number weighted size distributions clearly show a bimodal and lognormal in form with a nuclei mode in diameter range of 10 nm to 20 nm and an accumulation mode in diameter range of 50 nm to 80 nm.The total number and volume concentrations at high engine speed are larger than at middle engine speed.At the same engine speed,the total volume concentration increases with the increase of load.The total number concentrations increase with the increase of load at high speed,while the total number concentrations vary little with load at middle engine speed.At same engine speed,the number concentrations of accumulation mode increase with the increase of load.The number concentrations of nuclei mode increase with the increase of load at high engine speed,and the number concentration of nuclei mode varies little with load at middle engine speed.Maximum diameter of nuclei mode at middle engine speed gives smaller value than that at high engine speed.Maximum diameter of accumulation mode at middle engine speed gives larger value than at high engine speed.Nuclei mode gives large number fraction while accumulation mode gives large volume fraction.更多还原