国六轻型汽车超细颗粒排放特性研究

Study on Emission Characteristics of Ultrafine Particles from China6 Light-duty Vehicles

国内外汽车排放标准对空气动力学直径23 nm以上的固态颗粒提出控制要求,未对23 nm以下的颗粒做要求.文章采用满足PMP工作组技术要求的23 nm以下颗粒测试设备,选取6辆国六阶段轻型汽车,研究不同排放控制技术路线车辆在全球统一工况(WLTC)下的颗粒物排放特性.研究发现,在WLTC循环实验中,国六进气道喷射(PFI)车辆在超高速阶段产生大量10~23 nm的固态颗粒物,循环Sub23增量达到120%~150%;国六缸内直喷(GDI)和混合喷射(MxI)车辆Sub23增量在40%~60%之间;国六柴油颗粒捕集器(DPF)或汽油颗粒捕集器(GPF)车辆的Sub23增量在0~20%左右,DPF和GPF对SPN23和SPN10颗粒排放有较好的过滤作用.同时,WLTC循环颗粒瞬态排放特性和各速度段排放结果表明,冷起动仍是车辆SPN23和SPN10排放的主要阶段.

At present,solid particles with aerodynamic diameters above 23 nm are required to be controlled by domestic and foreign vehicle emission standards,but particles below 23 nm are not required.In this paper,particle emission characteristics of six China6 light-duty vehicles equipped with different emission control technology routes are studied under the worldwide harmonized light vehicles test cycle(WLTC)by using particle testing equipment meeting the requirements of PMP.It is found that the PFI vehicle produces a large number of solid particles at 10 nm~23 nm during the period of WLTC extra high-speed phase,and the Sub23 increment of the cycle is the highest,which reaches 120%~150%.The Sub23 increment of GDI and MxI vehicles ranges from 40%to 60%.For the vehicles equipped with a diesel particle filter(DPF)or gasoline particle filter(GPF),the increment of Sub23 is about 0~20%.Both DPF and GPF show good particle filtering performance for SPN23 and SPN10.Meanwhile,the results of particle transient and phase emission during the WLTC cycle show cold start is still the main stage of SPN23 and SPN10 emission for most vehicles.