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Zhihua Liu Asad Naeem Shah Yunshan Ge Yan Ding Jianwei Tan Lei Jiang Linxiao Yu Wei Zhao Chu Wang Tao Zeng 《环境科学学报(英文版)》2011,23(5):798-807
The effects of continuously regenerating diesel particulate filter (CRDPF) systems on regulated gaseous emissions, and number-size
distribution and mass of particles emanated from a diesel engine have been investigated in this study. Two CRDPF units (CRDPF-1
and CRDPF-2) with di erent specifications were separately retrofitted to the engine running with European steady-state cycle (ESC).
An electrical low pressure impactor (ELPI) was used for particle number-size distribution measurement and mass estimation. The
conversion/reduction rate (RCR) of hydrocarbons (HC) and carbon monoxide (CO) across CRDPF-1 was 83% and 96.3%, respectively.
Similarly, the RCR of HC and CO and across CRDPF-2 was 91.8% and 99.1%, respectively. The number concentration of particles
and their concentration peaks; nuclei mode, accumulation mode and total particles; and particle mass were highly reduced with the
CRDPF units. The nuclei mode particles at downstream of CRDPF-1 and CRDPF-2 decreased by 99.9% to 100% and 97.8% to 99.8%
respectively; and the particle mass reduced by 73% to 92.2% and 35.3% to 72.4%, respectively, depending on the engine conditions.
In addition, nuclei mode particles increased with the increasing of engine speed due to the heterogeneous nucleation initiated by the
higher exhaust temperature, while accumulation mode particles were higher at higher loads due to the decrease in the air-to-fuel ratio
(A/F) at higher loads. 相似文献
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During the 2012 Lanzhou International Marathon, the local government made a significant effort to improve traffic conditions and air quality by implementing traffic restriction measures. To evaluate the direct effect of these measures on urban air quality, especially particle concentrations and their size distributions, atmospheric particle size distributions(0.5–20 μm) obtained using an aerodynamic particle sizer(model 3321, TSI, USA) in June 2012 were analyzed. It was found that the particle number, surface area and volume concentrations for size range 0.5–10 μm were(15.0±2.1) cm-3,(11.8±2.6) μm2/cm3and(1.9±0.6) μm2/cm3, respectively, on the traffic-restricted day(Sunday), which is 63.2%, 53.0% and 47.2% lower than those on a normal Sunday. For number and surface area concentrations, the most affected size range was 0.5–0.7 and 0.5–0.8 μm, respectively, while for volume concentration, the most affected size ranges were 0.5–0.8, 1.7–2.0 and 5.0–5.4 μm. Number and volume concentrations of particles in size range 0.5–1.0 μm correlated well with the number of non-CNG(Compressed Natural Gas) powered vehicles, while their correlation with the number of CNG-powered vehicles was very low, suggesting that reasonable urban traffic controls along with vehicle technology improvements could play an important role in improving urban air quality. 相似文献