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1.
Huan Jing Ke Xue ; 41(1): 133-138, 2020 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854913

RESUMO

In typical cities of East China, more than 900 non-road vehicles were tested for exhaust smoke. Based on the investigation of the properties of these non-road vehicles, exhaust smoke intensities for different kinds of non-road vehicles are recommended. We also quantitatively study the differences in smoke intensity among vehicle age, vehicle power, test conditions, and fuels. The results showed that smoke intensity of non-road vehicles was (1.02±0.57) m-1 and that Ringelmann smoke was 2.10±0.19. In comparison to Chinese national standard (GB 36886), approximately 12%-25% of tested non-road vehicles' smoke intensity exceeded the standard limit. The smoke intensity of 80% of tested non-road vehicles was higher during start-up than under free acceleration. In comparison to ordinary diesel, the smoke intensities of tested non-road vehicles that used automotive diesel were lower. The instantaneous increase in fuel injection during start-up, as well as poor fuel quality, can directly affect the exhaust smoke of non-road vehicles.

2.
Huan Jing Ke Xue ; 39(10): 4463-4471, 2018 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-30229592

RESUMO

The selective catalytic reduction system (SCR) is an essential method to reduce NOx emissions from heavy-duty diesel engine-powered vehicles, which include conventional diesel buses and diesel-electric hybrid buses. Using wireless remote communication technology, the SCR system status and NOx emissions were reviewed for ten fully-operational hybrid buses from Hangzhou China in this research. Under the internal combustion engine mode, the main factors studied were vehicle speed, engine operation conditions and environment temperature, impact on the SCR catalyst outlet temperature and NOx concentration and dosing rate of the urea injector of the SCR system. The research result shows that (32.4±4)% of the operational time of the hybrid buses with SCR system was spent in internal combustion engine mode, and under (26.9±11)% of the operation time of this mode, the SCR system did not dose urea. The average NOx emission reduction rate of the SCR system, when operating normally with hybrid buses, is about 59%. The main reasons for the high NOx emission of the diesel-electric hybrid buses in operation condition are poor satisfaction of the requirements of the SCR system control strategy and the SCR catalyst's low temperature conversion efficiency. Whenever the speed of the hybrid buses was above 40 km·h-1, the SCR catalyst outlet temperatures were higher than the 230℃, and the NOx emission concentrations were significantly reduced, as the urea injector working proportion and urea quantity increased. In the winter, the SCR catalyst outlet temperature and urea injection quantity dropped with the reduced environment temperature, which led to increased NOx emissions.

3.
Huan Jing Ke Xue ; 39(7): 3110-3117, 2018 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-29962133

RESUMO

Organic carbon (OC) and elemental carbon (EC) emission factors from 27 State 3-5 light-duty gasoline vehicles (LDGVs) were tested in this study using a CVS (Constant Volume Sampling) system on a dynamometer. The influences of start conditions, driving cycles, and fuel injection technologies on the OC and EC emissions were analyzed. The results show that the OC emission factors of the tested State 3 to 5 LDGVs were (2.09±1.03), (1.59±0.78), and (0.75±0.31) mg·km-1, respectively, and the EC emission factors were (1.98±1.42), (1.57±1.80), and (0.65±0.49) mg·km-1. Both OC and EC emissions significantly decreased with the promotion of emission standards. The OC/EC ratios were 1.54±0.92, 1.53±0.91, and 1.47±0.66, respectively. OC1, OC2, EC1, and EC2 were the most important carbonaceous components from LDGVs, accounting for 15%, 20.6%, 22.2%, and 21.7%, respectively. OC and EC emission factors under cold-start conditions were 1.4 and 1.8 times those under hot-start conditions. OC and EC emission factors for highway cycles were 2 and 4 times those for urban cycles. OC emission factors from GDI (Gasoline Direct Injection) engines were close to those from PFI (Port Fuel Injection) engines. However, their EC emission factors were 1.7 times those from PFI engines. With the increasing popularity of GDI engines in LDGV fleets in China, the EC emissions from these engines should be paid more attention in the future.

4.
Huan Jing Ke Xue ; 38(7): 2738-2746, 2017 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-29964612

RESUMO

Based on site investigation of non-road vehicles in Shanghai and Hangzhou located in east China, non-road vehicle emission inventory in 2014 was established in these cities as well as its emission inventory technology. Characteristics of non-road vehicle were also analyzed, including classification, type of fuel, power and emission standard. The results showed that diesel consumed by non-road vehicles was 6.1×105 t in Shanghai and 3.2×105 t in Hangzhou; NOx emission was 3.09×104 t in Shanghai and 1.72×104 t in Hangzhou; PM2.5 emission was 1.41×103 t in Shanghai and 8.1×102 t in Hangzhou, 2014. Emissions from excavators and other construction equipment contributed the most in non-road vehicle emission inventory. Non-road vehicle has become one of the important sources of urban air pollution, whose NOx emissions accounted for 11.1% of all urban sources in Shanghai and 16.1% in Hangzhou, and accounted for 18.5% of mobile sources in Shanghai and 32.2% in Hangzhou.

5.
Huan Jing Ke Xue ; 38(6): 2294-2300, 2017 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965346

RESUMO

Gaseous emissions from 25 State 2-5 light-duty gasoline vehicles were tested by Vehicle Mass Analysis System (VMAS) and CVS (Constant Volume Sampling) system, respectively. The correlations of emission factors of tested vehicles measured by these 2 methods were analyzed. The results showed that emission factors of light-duty gasoline vehicle had a decreasing trend with the promotion of emission standard. There were some high-emitting vehicles in the fleet of tested State 2 and State 3 vehicles, but fewer in State 4 or Stated 5 vehicle fleet. The correlations of the emission factors measured by the 2 methods deteriorated with the promotion of emission standard. The relative bias of CO and HC+NOx emission factors measured by the 2 methods reached 197% and 177%, respectively. The correlation coefficient of emission factors of higher-emitting vehicles was 0.75-0.85, while that of lower-emitting vehicles was only 0.46. If tighter emission standard of in-use light-duty gasoline vehicle was adopted, the false positive rate of measurement results by VMAS would rise significantly. In summary, VMAS method is hard to be applied in the emission measurements of light-duty gasoline vehicles with stricter emissions standard. It is necessary to conduct more studies on sophisticated in-use vehicle measurement system.

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