铁基FBC对柴油机颗粒荷电特性的影响

Effect of Fe-FBC on Charge Characteristic of Diesel Particles

按质量比100mg/kg,200mg/kg和300mg/kg向国Ⅴ柴油中加入铁基添加剂(Fe-FBC)制备Fe100,Fe200,Fe3003种燃油,基于自制双极荷电实验台,分析荷电电压对排气颗粒荷电特性的影响。采用发动机粒径谱仪和Zeta电位分析仪测量颗粒粒径分布特征、表面电荷量和柴油机颗粒捕集器(DPF)数量浓度捕集效率。结果表明:在同一工况下,随着燃油中Fe元素含量增加,颗粒峰值浓度粒径向小粒径方向偏移;荷电凝并技术(ECA)可以使柴油机排气中小粒径颗粒凝并成较大粒径颗粒;Fe-FBC可以提高颗粒凝并效率,当颗粒处于相同荷电电压时,Fe300燃油颗粒的凝并效率更大;提高荷电电压可以增加颗粒表面Zeta电位和荷电量,Fe-FBC加入燃油中能够明显提升排气颗粒的荷电性能,其中Fe300颗粒在荷电电压为15kV时表面Zeta电位和荷电量增长速率最大;ECA能够增加DPF在6.04~12.4nm处捕集效率,当荷电电压为15kV时,柴油与Fe300的DPF捕集效率分别增加12.2%和23.8%。

Fe-based additives (Fe-FBC) were added to China V diesel fuel according to the mass fraction of 100 mg/kg, 200 mg/kg and 300 mg/kg in order to prepare the blended fuels of Fe100, Fe200 and Fe300. On a self-made bipolar charge test bench, the effect of charge voltage on the charge characteristic of exhaust particles was analyzed. Engine exhaust particle size device and Malvern ZEN analyzer were used to further measure the particle size distribution, surface charge and DPF number concentration collection efficiency. The results show that the particle size of peak concentration becomes smaller with the increase of Fe content under the same engine operating condition. Electrical charge agglomeration(ECA)can aggregate the small and medium-sized particles to the larger particles in the exhaust of diesel engine. Fe-FBC can improve aggregation efficiency of particles and so the aggregation efficiency of Fe300 fuel particles is higher at the same charge voltage. Increasing the charge voltage can increase the Zeta potential and charge on the particle surface. The charge performance of exhaust particles improves significantly after adding Fe-FBC. The increase rate of Zeta potential and charge on the surface of Fe300 particles is the highest at the charge voltage of 15 kV. ECA can increase the DPF collection efficiency at 6.04~12.4 nm. The DPF efficiency of diesel and Fe300 increases by 12.2% and 23.8% respectively at the charge voltage of 15 kV.