• Emissions from 53 in-use diesel-fueled off-road equipment were measured.• There exists a large off-road equipment variability in emissions.• Engine operations have significant impacts on real-world tailpipe emissions.• Emission inventory development should take into account job duties and operations. The objective of this paper is to quantify the variability in emissions of off-road equipment using a portable emission measurement system. A total of 53 commonly used equipment for agriculture, base construction, paving construction, and material handling were selected. Time-based and fuel-based emissions were quantified by different duty and engine modes. Three duty modes (idling, moving, and working) were used. Ten engine modes were defined based on normalized engine revolutions-per-minute and manifold absolute pressure, respectively. Composite emission factors taking into account both duty modes and its corresponding time percentage during a typical duty cycle were estimated. Results showed that there existed a large off-road equipment variability in emissions. Depending on duty and engine modes, time-based NO emissions ranged from 3.1 to 237.9, 29.1‒1475.6, 83.2‒681.6, and 3.2‒385.2 g/h for agriculture, base construction, paving construction and material handling equipment, respectively while for fuel-based NO emissions these ranges were 5.3‒52.0, 11.7‒69.0, 4.8‒30.8, and 11.0‒54.6 g/kg, respectively. Furthermore, emission factors derived from this study exhibited a much larger variability compared to those used in NONROAD by US EPA and National Guideline for Off-road Equipment of China. This implied that localized measurements of emissions are needed for improvement of accuracy of emission inventory. Furthermore, both equipment types and operations should be considered for development of emission inventory and control strategy. 相似文献
Tailpipe emissions from light-duty gasoline vehicles usually deteriorate over time. The accumulation of engine deposits due to inadequate gasoline detergency is considered to be one of the major causes of such emission deterioration. Six in-use light-duty gasoline vehicles in Beijing were tested to investigate the impact of engine deposits on emissions of hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). Emissions under cold start and hot running test conditions from the six light duty vehicles were measured before and after engine deposits were removed. Results show that although individual vehicles reacted differently for each of the pollutants, elimination of engine deposits on average reduced HC emissions under hot running conditions by 29.4%, CO emissions under cold start conditions by 23.0% and CO emissions under hot running conditions by 35.5% (t < 0.05 in all cases). No pollutant emissions increased with statistical significance (t < 0.05) after the removal of engine deposits. Variations of emission changes upon removal of engine deposits were observed. Such variations are in line with previous studies, implying that the impact patterns of engine deposits on vehicle emissions may be subject to many influencing factors that are not fully understood and difficult to control under all conditions. A statistical view of the impact of engine deposits on vehicle emissions may be appropriate for evaluation of emissions reductions across a city or a country. It is necessary to maintain sufficient and effective gasoline fuel detergency in practice to keep the engines clean and in turn reduce vehicle emissions. 相似文献
Utilizing oil extracted from waste engine oil and waste plastics, by pyrolysis, as a fuel for internal combustion engines has been demonstrated to be one of the best available waste management methods. Separate blends of fuel from waste engine oil and waste plastic oil was prepared by mixing with diesel and experimental investigation is conducted to study engine performance, combustion and exhaust emissions. It is observed that carbon monoxide (CO) emission increases by 50% for 50% waste plastic oil (50WPO:50D) and by 58% for 50% waste engine oil (50WEO:50D) at full load as compared to diesel. Unburnt hydrocarbon (HC) emission increases by 16% for 50WPO:50D and by 32% for 50WEO:50D as compared to diesel at maximum load. Smoke is found to decrease at all loading conditions for 50WPO:50D operation, but it is comparatively higher for 50WEO:50D operation. 50WPO:50D operation shows higher brake thermal efficiency for all loads as compared to 50WEO:50D and diesel fuel operation. Exhaust gas temperature is higher at all loads for 50WPO:50D and 50WEO:50D as compared to diesel fuel operation.
Twenty five measurements in triplicate of heterotrophic activity in sea water showed good reproducibility. The mean coefficient of variation was 6.2%, which is lower than the coefficient of variation obtained with a similar method for primary production measurements. This result indirectly confirms that most heterotrophic activity can be attributed to a great number of small cells, i.e., bacteria which, if not free-swimming, are fixed to particles of smaller size than the average phytoplankton. The good reproducibility obtained also suggests that there was no extraneous contamination despite non-sterile working conditions. 相似文献
The contamination of soils with pollutants by human activities has increased over a period of some decades. Deposited pollutants are immobilized in different ways depending on their chemical properties, or they are biologically available. This potential hazard requires a permanent control. An extensive investigation of topsoil in the surroundings of the fertilizer factory at Dorndorf-Steudnitz (Thuringia) was carried out to assess the size and extension of contamination and to estimate the potential risk which originates from the deposited pollutants. The fertilizer factory at Dorndorf-Steudnitz was one of the biggest dust emission sources in the middle part of the Saale river valley. Considerable damages of vegetation could be noticed already in the seventies and eighties. The trees and other plants in the neighbourhood of the factory died. The loadings of the investigated area may be attributed to a direct influence of gaseous and also of dustlike pollutants on the vegetation and resorption from the soil. Frequently, the content of pollutants in soils varies considerably. For this reason a univariate statistical evaluation of the data is not usually adequate. The use of geostatistical methods permits the characterization of the spatial structure of the investigated area and the undistorted assessment of the pollutant contents at unsampled points. The degree and extension of the contamination can be determined on the basis of the kriging estimation. The classification of analyzed features in regard to common sources of contamination can be realized by means of methods of multivariate data analysis. 相似文献