NOx Emission Factors Research Articles

A 24-h real-time emissions assessment of 41 uncontrolled household raw coal combustion stoves in four provinces of Northern China

Abstract Air pollutants from household heating stoves are attracting growing public concern. Although several previous studies have investigated pollutant emissions from the household heating stoves, the emission factors reported might be less representative because most of the studies conducted the measurement only during the relatively short period for one combustion process, which is far from the real case. In this study, therefore, 24-h continuous measurements of CO, PM2.5, SO2, NOx, and CO2 emissions from the chimneys of household stoves fueled with raw coal in four provinces of Northern China were conducted during winter heating periods to reveal their actual emissions. The measured emission factors of CO, CO2, SO2, NOx, and PM2.5 were 6.163 ± 2.113, 82.875 ± 4.709, 0.190 ± 0.113, 0.076 ± 0.046, and 0.127 ± 0.061 g/MJ for the radiant heating stove; 5.801 ± 2.323, 86.602 ± 8.376, 0.083 ± 0.048, 0.062 ± 0.033, and 0.119 ± 0.081 g/MJ for the water heating stove, respectively. Compared with previously published results with relatively short-time measurements, a lower PM2.5 emission factor (p

Determination of gaseous and particulate emission factors from road transport in a Middle Eastern capital

Road transport is a major source of anthropogenic emissions especially in the Middle East where the regulations enforcement is generally poor. This study aims to quantify the Emission Factors (EF) of traffic-related gaseous and particulate pollutants inside the Salim Slam urban tunnel in Beirut, Lebanon. The fuel-based emission factors of measured pollutants were from the carbon mass balance model. The EF determined showed general higher values than those reported in recent studies from European and American countries, even for speciated NMVOC. The average CO and NOx emission factors for the mixed fleet (HDV + LDV) were determined to be 10.52 ± 3.00 g km−1 and 2.20 ± 0.57 g km−1 respectively, while the EF for PM2.5 55 ± 27 mg km−1. Moreover, IVOC species from gaseous phase were reported for the first time in the region. A reduction trend was observed in comparison with the previous tunnel study from Lebanon, however there is still a need to have tougher regulations to control the local practices such as removal of catalytic converter, adjustment of engine parameters for inspection, etc. The comparison of the EF to those calculated through EMEP or IPCC methodologies shows the need to take local practices while establishing national emission inventories.

The spatial-temporal pattern of sintered flue gas emissions in iron and steel enterprises of China

This study provides a comprehensive survey of emissions from the sintering process in China to give an indication of the actual emission situation. Survey data were taken from China’s continuous emission monitoring system (CEMS) from 209 sintering plants from 2015 to 2016. The standard-reaching rate of national emissions and the oxygen content ratio of the sintering process were considered as two indicators to evaluate the emissions level. Moreover, the CEMS-based emission factor (EF) estimation method was applied to improve the accuracy of EF estimation compared with existing methods. The emission concentration of total suspended particles (PMTPS), SO2 and NOx decreased, and the standard-reaching rate of these three pollutants increased from 92%, 94% and 98%, respectively, to almost 100% during the research period. The average emission concentration in eastern China was lower than that in western China. More samples exceeded the oxygen regulation of <16% in 2016 than in 2015. This indicates that most plants should control air leakage to decrease the oxygen content. The national monthly average EF of PMTPS and SO2 decreased from 0.013 to 0.009 kg/ton-sintering and from 0.036 to 0.026 kg/ton, respectively, during the research period. The EF of NOx remained around 0.068 kg/ton. These results are much lower than the results of former studies.

Seasonal and Long-Term Trend of on-Road Gasoline and Diesel Vehicle Emission Factors Measured in Traffic Tunnels

Emissions of gaseous and particulate pollutants from on-road gasoline and diesel vehicles were measured in a traffic tunnel under real-world driving conditions. Emission factors were attributed to gasoline and diesel vehicles using linear regression against the fraction of fuel consumed by diesel vehicles (% fuelD). We measured 67% higher NOx emissions from gasoline vehicles in winter than in spring (2 versus 1.2 g NO2 kg fuel−1). Emissions of CO, NOx, and particulate matter from diesel vehicles all showed impacts of recent policy changes to reduce emissions from this source. Comparison of our measurements to those of a previous study ~10 years prior in a nearby traffic tunnel on the same highway showed that emission factors for both gasoline and diesel vehicles have fallen by 50–70%. To further confirm this long-term trend, we summarized emission factors measured in previous tunnel studies in the U.S. since the 1990s. More restrictive emission standards are effective at reducing emissions from both diesel and gasoline vehicles, and decreases in observed emissions can be mapped to specific vehicle control policies. The trend of diesel-to-gasoline emission factor ratios revealed changes in the relative importance of vehicle types, though fuel-specific emission factors of NOx and elemental carbon (EC) are still substantially larger (~5–10 times) for diesel vehicles than gasoline vehicles.

Gaseous Emissions from a Seagoing Ship under Different Operating Conditions in the Coastal Region of China

Pollution caused by ship emissions has drawn attention from various countries. Because of the high density of ships in ports, channels, and anchorages and their proximity to the densely populated areas, ship emissions will considerably impact these areas. Herein, a Chinese seagoing ship is selected and a platform is established for monitoring the ship emissions to obtain detailed characteristics of the ship’s nearshore emissions. The ship navigation and pollution emission data are obtained under six complete operating conditions, i.e., berthing, manoeuvring in port, acceleration in a channel, cruising, deceleration before anchoring, and anchoring. This study analyzes the concentrations of the main emission gases (O2, NOX, SO2, CO2, and CO) and the average emission factors (EFs) of the pollution gases (NOX, SO2, CO2, and CO) based on the engine power under different operating conditions. Results show that the change in O2 concentration reflects the load associated with the main engine of the ship. The NOX, SO2, and CO2 emission concentrations are the highest during cruising, whereas the peak CO emission concentration is observed during anchoring. The average EFs of NOX and SO2 based on the power of the main engine are the highest during cruising, and those of CO2 and CO are the highest after anchoring. The ship EFs are different during acceleration and deceleration. By comparing the EFs along the coast of China and the global EFs commonly used to perform the emission inventory calculations in China, the NOX EFs under different operating conditions is observed to be generally lower than the global EFs under the corresponding operating conditions. Furthermore, the SO2 EF is considerably affected by the sulfur content in the fuel oil and the operating conditions of the ship. The average CO2 EFs are higher than the global EFs commonly used during cruising, and the CO EFs are higher than the global EFs under all the conditions. Our results help to supplement the EFs for this type of ship under different operating conditions, resolve the lack of emission data under anchoring conditions, and provide data support to conduct nearshore environmental monitoring and assessment.

Emission inventory for on-road traffic fleets in Greater Yangon, Myanmar

On-road traffic emissions of Greater Yangon in 2015 were estimated using IVE model. Local surveys revealed the engine technology distributions, driving activities and flows for the fleets of bus, personal car (PC), pickup (PU), taxi, van and light duty truck. Vehicles in Greater Yangon were relatively new but recent use of leaded gasoline caused deactivation of catalytic converters that bring about high emission factors (EFs) of CO, VOC and NOx from gasoline-powered vehicles. Pre-Euro diesel-powered buses and trucks were high PM emitters while pre-Euro and Euro1 gasoline vehicles were high emitters of CO and VOC. Composite EFs of CO and VOC were the highest for PU (45.1 and 3.2 g/km, respectively) followed by taxi (34.2 and 2.6 g/km, respectively). CNG vehicles with their small number and low EFs contributed the least to total on-road traffic emissions. The bus fleet, despite being diesel-powered at only 28%, still had the highest EFs of PM and NOx, 1.6 and 2.7 g/km, respectively. Total emissions for 2015 (base case) in Greater Yangon from six surveyed fleets and the motorcycle fleet of CO; VOC; NOx; PM; BC; OC; CO2; CH4 and air toxics, in Gg/year, were 358; 41; 24; 3.8; 1.6; 0.9; 5358, 6.8 and 3.1, respectively. If all vehicles in this domain at least comply with Euro3 standard, the collective emission reduction from the base case of the air pollutants would be 71% while that of GWP (GHGs and short-lived climate pollutants) 43%, hence showing significant potential co-benefits.

Sensitivity analysis of area-wide, mobile source emission factors to high-emitter vehicles in Los Angeles

The absolute principal component scores (APCS) model was applied to on-road, background-adjusted measurements of NOx, CO, CO2, black carbon (BC), and particle number (PN) obtained from a continuously moving platform deployed during 16 afternoon sampling periods in Los Angeles, CA. High-emitter biasing observations were separated from the vehicle fleet population based on a sensitivity analysis of different a priori screening values of the ratio of CO to CO2. A BC/PN-rich feature consistent with heavy-duty vehicle exhaust, and a separate CO/CO2-rich feature consistent with light-duty vehicle exhaust, described 66% of the variance of the observations. We used bootstrapped APCS model predictions to estimate area-wide, average fuel-based emission factors and their respective 95% confidence limits. If no screening was used, we obtained incongruous average emission factors relative to recent field studies for NOx, CO, BC and PN (5.1, 2.0, 0.13 g/kg, and 1.0 × 10^15 particles/kg for heavy-duty vehicles, and 2.0, 111, 0.023 g/kg, and 0.09 × 10^15 particles/kg for light-duty vehicles, respectively). However, if reasonable a priori screening values were applied, which differentiate measurements reflecting high-emitter outliers, average emission factors for NOx, CO, BC and PN (12.8, 4.0, 0.37 g/kg, and 2.6 × 10^15 particles/kg for heavy-duty vehicles, and 1.5, 40.9, 0.004 g/kg, and 0.08 × 10^15 particles/kg for light-duty vehicles, respectively) were consistent with previous estimates based on remote sensing, vehicle chase studies, and recent dynamometer tests.

Real emissions, driving patterns and fuel consumption of in-use diesel buses operating at high altitude

We report simultaneous measurements of fuel consumption, driving patterns, and CO2, CO, and NOx emission factors for diesel passenger buses under real operating conditions in high altitude cities (>2000 masl) and in mountainous regions with an average road grade of 4%. These measurements were obtained using a Portable Emission Measurement System (PEMS) monitoring a sample of 15 buses during eight months of daily operation. For a city with a high level of vehicular traffic (Mexico City), we obtained an average fuel consumption of 0.41 L/km and emission factors of 965.8, 41.4, and 5.3 g/km for CO2, CO, and NOx, respectively. Fuel consumption and CO2 emissions were within expected values. However, CO emissions were approximately three times higher while the NOx emission were half of the reported values in the literature for buses of similar technology working at low altitude.

Regulated emission characteristics of in-use LNG and diesel semi-trailer towing vehicles under real driving conditions using PEMS

On-road driving emissions of six liquefied natural gas (LNG) and diesel semi-trailer towing vehicles (STTVs) which met China Emission Standard IV and V were tested using Portable Emission Measurement System (PEMS) in northern China. Emission characteristics of these vehicles under real driving conditions were analyzed and proved that on-road emissions of heavy-duty vehicles (HDVs) were underestimated in the past. There were large differences among LNG and diesel vehicles, which also existed between China V vehicles and China IV vehicles. Emission factors showed the highest level under real driving conditions, which probably be caused by frequent acceleration, deceleration, and start-stop. NOx emission factors ranged from 2.855 to 20.939 g/km based on distance-traveled and 6.719–90.557 g/kg based on fuel consumption during whole tests, which were much higher than previous researches on chassis dynamometer. It was inferred from tests that the fuel consumption rate of the test vehicles had a strong correlation with NOx emission, and the exhaust temperature also affected the efficiency of Selected Catalytic Reduction (SCR) after-treatment system, thus changing the NOx emission greatly. THC emission factors of LNG vehicles were 2.012–10.636 g/km, which were much higher than that of diesel vehicles (0.029–0.185 g/km). Unburned CH4 may be an important reason for this phenomenon. Further on-road emission tests, especially CH4 emission test should be carried out in subsequent research. In addition, the Particulate Number (PN) emission factors of diesel vehicles were at a very high level during whole tests, and Diesel Particulate Filter (DPF) should be installed to reduce PN emission.

Incorporating health co-benefits into regional carbon emission reduction policy making: A case study of China’s power sector

How to maximize the synergies between CO2 and conventional air pollutants (CAP) emission reductions have been extensively discussed in previous studies. However, few studies have explored the essential policy concern, which is, how to maximize the social benefits including both carbon mitigation and human health co-benefits from the co-abated conventional air pollutants. Besides, for some sectors that have extensive inter-regional trade, using more low-carbon technologies to produce goods (and thus reducing its own CO2 emissions) in one region may influence the need of goods imported from another region and consequently the associated conventional air pollutants emissions. Therefore, the health co-benefits may also be transferred to the other regions. This transfer effect has seldom been quantified before. To bridge these research gaps, this paper took China’s power sector as an example and quantified the operating margin (OM) emission factors of SO2, NOX and PM2.5 in China’s six power grids. Then the co-abatement rates of these three pollutants when reducing each kiloton of CO2 in different grids were calculated. Finally, considering different grids’ meteorological conditions, population densities, baseline incidences, baseline death rates, and the inter-grid electricity trade, this paper computed and compared the values and regional distribution of health co-benefits per kiloton of CO2 reduced. It is found that grids with the highest co-abatement rates in conventional air pollutants do not necessarily bring maximum health co-benefits. Although the northeast grid could achieve the largest co-reduction in NOX and PM2.5, it is the south grid that has the largest health co-benefits. The differences in health co-benefits of the same amount of CO2 reduced among grids vary as much as fivefold. Besides, the share of trans-grid health co-benefits can be as high as 14.1% if CO2 reduction takes place in the east grid. Therefore, it is suggested that the health co-benefits of CO2 reduction and their trans-regional distribution should be taken seriously when making regional carbon emission reduction plans, in order to maximize the social benefits of CO2 reduction.

Emissions Characteristics of Hazardous Air Pollutants from the Incineration of Sacrificial Offerings

The incineration of sacrificial offerings generates numerous hazardous air pollutants, including particulate matter (PM), CO, SO2, NOx and non-methane hydrocarbons (NMHC), which has significant effects on the environment and human health. However, due to the concealment of sacrificial offerings incineration, the emission of such pollutants has not received sufficient attention. Relevant quantification of the emission, emission factors and pollution control measures for this pollution source are lacking. To address these problems, herein, we quantified the particulate matter and its chemical composition and the emission levels of gaseous pollutants, including SO2, NOx, NMHC and CO, by performing incineration experiments of four typical sacrificial offerings (Joss paper, Funeral wreath, Taoist paper art and Yuanbao paper), and obtained the emission factors and emission characteristics for the incineration of sacrificial offerings. Therefore, this study lays the foundation and provides support for establishing an emission inventory of the air pollutants from the incineration of sacrificial offerings and introducing corresponding pollution control measures. The results show that the emission concentrations of CO and total suspended particulate (TSP) from the incineration of sacrificial offerings greatly exceed the emission standard, with averages of 621.4 mg m−3 and 142.9 mg m−3 at 11% oxygen content, respectively. The average emission factors of SO2, NOx, NMHC, CO, PM10 and PM2.5 for the incineration of the four offerings are (0.47 ± 0.17) kg t−1, (2.46 ± 0.35) kg t−1, (5.78 ± 2.41) kg t−1, (32.40 ± 8.80) kg t−1, (4.23 ± 0.71) kg t−1 and (2.62 ± 0.48) kg t−1, respectively, among which the emission intensities of NMHC and CO are relatively high. Among the different types of sacrificial offerings, the overall average emission factor of air pollutants generated from the incineration of Yuanbao paper is the highest, which is mainly due to the low burning efficiency and the coating material. For the chemical composition of the particulate matters, ions, OC, EC and metal elements account for proportions of the PM2.5 at (23.55 ± 10.37) %, (29.74 ± 9.95) %, (14.83 ± 6.55) % and (13.45 ± 4.88) %, respectively, indicating that the organic pollution is severe

Pollutant Emissions from Improved Cookstoves of the Type Used in Sub-Saharan Africa

ABSTRACT Emissions from traditional cookstoves are a major health concern in developing world households. Improved cookstoves can reduce fuel use and pollutant emissions and here we compare three types of improved cookstoves widely used in Sub-Saharan Africa. These are a raised-bed charcoal stove, a rocket-type stove using wood and straw, and a gasifier stove. Laboratory measurements were made of the main gaseous pollutants, particle size distribution and composition. The genotoxicity of the particles was assessed using a comet assay. The rocket-type stove using dry wood had the highest emission factors for particulate matter and NOX. Emissions of CO and CH4 were a factor of 6–7 higher from the charcoal stove compared with the other stoves tested in this work, and also higher for burning high moisture wood. Fuel properties were critical for emitted particle size, and for the emissions of NOX, black carbon and organic matter.

Benefits of current and future policies on emissions of China's coal-fired power sector indicated by continuous emission monitoring

Emission inventories are critical to understanding the sources of air pollutants, but have high uncertainties in China due in part to insufficient on-site measurements. In this study, we developed a method of examining, screening and applying online data from the country's improving continuous emission monitoring systems (CEMS) to reevaluate a “bottom-up” emission inventory of China's coal-fired power sector. The benefits of China's current national emission standards and ultra-low emission policy for the sector were quantified assuming their full implementation. The derived national average emission factors of SO2, NOx and particulate matter (PM) were 1.00, 1.00 and 0.25 kg/t-coal respectively for 2015 based on CEMS data, smaller than those of previous studies that may not fully recognize improved emission controls in recent years. The annual emissions of SO2, NOx and PM from the sector were recalculated at 1321, 1430 and 334 Gg respectively, 75%, 63% and 76% smaller than our estimates based on a previous approach without the benefit of CEMS data. The results imply that online measurement with proper data screening can better track the recent progress of emission controls. The emission intensity (the ratio of emissions to economic output) of Northwest China was larger than that of other regions, attributed mainly to its less intensive economy and industry. Transmission of electricity to more-developed eastern provinces raised the energy consumption and emissions of less-developed regions. Judged by 95 percentiles of flue-gas concentrations measured by CEMS, most power plants met the current national emission standards in 2015 except for those in Northwest and Northeast China, while plants that met the ultra-low emission policy were much scarcer. National SO2, NOx and PM emissions would further decline by 68%, 55% and 81% respectively if the ultra-low emission policy can be strictly implemented, implying the great potential of the policy for emission abatement.

Rethinking NOx emission factors considering on-road driving with malfunctioning emission control systems: A case study of Korean Euro 4 light-duty diesel vehicles

This study aims to quantify the differences between the standard laboratory-based NOx emissions factor (EF) and on-road measurements, and to estimate how much NOx emissions exceed the current EF under typical Korean road traffic conditions. Four Euro 4 light-duty diesel vehicles (LDVs) manufactured in Korea were driven on a chassis dynamometer and on test routes that included urban and rural roads and a motorway. NOx emissions, average speed, and acceleration were measured and calculated for each 1 km trip. We focused in particular on the possibility of vehicle malfunctions causing increased NOx emissions, and compared NOx emissions before and after the repair of faulty exhaust gas recirculation (EGR) valves, which are a key NOx reduction system for LDVs. The current NOx EF for Euro 4 LDVs only estimates 27–31% of on their on-road NOx emissions, and low acceleration during the standard driving cycle is a part of the reason for this weak representativeness. Another is the lack of tools with which to monitor EGR valve degradation. Even with fully functioning EGR valve hardware, the capability of vehicles to control NOx emissions differ in laboratory and on-road conditions; it is weaker for the latter compared to the former because the software controls are different. The findings here provide insights for different regions where Euro 4 LDVs are still in use, depending on their age. For Korea and the EU, where the fleet is old, accurate assessments of the real risk of NOx emissions are beneficial in terms of increasing the effectiveness of control measures. In countries where the Euro 4 fleet is still young, comprehensive changes are recommended for the on-board diagnostic system and the subsequent maintenance of the hardware and software of EGR valve.

The relationship between atmospheric pollutant emissions and fuel qualities of inland vessels in Jiangsu Province, China

ABSTRACTAir pollution caused by ship exhaust emission is receiving more and more attention. The physical and chemical properties of fuels, such as sulfur content and PAHs content, potentially had a significant influence on air pollutant emissions from inland vessels. In order to investigate the effects of fuel qualities on atmospheric pollutant emissions systematically, a series of experiments was conducted based on the method of actual ship testing. As a result, SO2, PM and NOx emission rates all increased with the increase of main engine rotating speed under cruise mode, while PM and NOx emission factors were inversely proportional to the main engine rotating speed. Moreover, SO2 emission factor changed little with the increase of the main engine rotating speed. In summary, the fuel-dependent specific emission of SO2 was a direct reflection of the sulfur content in fuel. The PM emission increased with the increase of sulfur content and PAHs content in fuel. However, fuel qualities impacted little on NOx emissions from inland vessels because of NOx formation mechanisms and conditions.Implications: Ship activity is considered to be the third largest source of air pollution in China. In particular, air pollutants emitted from ships in river ports and waterways have a direct impact on regional air quality and pose threat on the health of local residents owing to high pollutants concentration and poor air diffusion. The study on the relationship between air pollutant emissions and fuel quality of inland vessels can provide foundational data for local authority to formulate reasonable and appropriate policies for reducing atmospheric pollution due to inland vessels.

Characterization and quantification of PM2.5 emissions and PAHs concentration in PM2.5 from the exhausts of diesel vehicles with various accumulated mileages

Road traffic is one of the main sources of particulate matter in the atmospheric environment. Notwithstanding its significance, there are noteworthy challenges in quantitative assessment of its contribution to the concentrations of airborne. This study reports on the characterization and quantification of PM2.5 emissions and PAHs concentration in PM2.5 from the exhausts of on-road diesel vehicles with various accumulated mileages in Kaohsiung City, Taiwan. Urban areas could be a subject matter not just in connection to deprived air quality, but similarly to pollution of other significant environmental media by air contaminants. To that end, our study intends to estimate the PM2.5 emissions from diesel vehicles using diesel fuels and to analyze the PM2.5 emissions and PAHs concentration in PM2.5. In this study, particulate matters (PM2.5) were characterized and quantified from a place impacted by diesel vehicles fueled with diesel in Kaohsiung City, Taiwan. The tested diesel vehicles with various accumulated mileages overs the model year comprising of the vehicles registered from 1984 to 2012 from different manufacturers (or brands) ranging from 8733 to 965,026 km (average 445,433 km) accumulative mileages. Exhaust constituents include CO, NOx, PM2.5 and particle phase PAHs. The concentrations of twenty-one (21) priority polycyclic aromatic hydrocarbons (PAHs) were studied in the samples by their relationship with atmospheric PM2.5. However, in relations to cumulative mileages, lower cumulative mileage (mileage <20,000 km) has the lowest CO and NOx emission factors. The mileage ranged from 20,001 to 30,000 km had an increased CO and NOx emission factors, respectively. Interestingly, with the increased high number of mileages ranged from 30,001 to 50,000 km, CO and NOx emission factor was observed to be declining, respectively. This could be attributed to the technological changes on new diesel vehicle models. But nonetheless, the trend of CO emission factor was found to be higher with an increasing of cumulative mileages as compared to the mileage that reached lower than 30,000 km.

Emission Factors of NOx, SO2, PM and VOCs in Pharmaceuticals, Brick and Food Industries in Shanxi, China

ABSTRACT The acquisition of accurate emission factors (EFs) of pollutants is an inevitable step to the establishment of emission inventories for development of pollution control policies. The current studies were focused on large-scale industries (LSIs) although tremendous pollutants emitted from the small-scale industries (SSIs) with small coal-fired boilers (SCFBs) ascribe to the deficiency of pollutant removal facilities (RFs). A systematic field sampling and measurements conducted in 51 enterprises involving production of pharmaceuticals, brick and food to obtain the EFs of SO2, NOx, PM, and VOCs (SNPV) associated with coal consumption (EFI), industrial output (EFII), and product yield (EFIII). Among them, PM-RFs were all equipped except for 3 brick factories, no NOx- and VOCs-RFs were installed, and SO2-RFs were installed in part. Obvious fluctuations existed in EFI and EFII values among 51 companies owning to the differences of pollutant removal efficiencies, coal compositions, annual outputs, production processes, and products. Co-burning of coal and coal gangue (raw material) in brick production weakened the correlation between sulfur contents in coal and SO2 EFI values. The using of organic solvents in drug making process promoted the emission of VOCs. SO2 EFs in factories with RFs were much lower than those factories without RFs. SO2 EFs dominated over those of PM and NOx among three kinds of enterprises, especially in brick companies. For EFI (in kg t–1), food industry possessed highest value for SO2, PM, and NOx, while the maximum value for VOCs occurred at pharmaceuticals industry. Due to the low output values of brick companies, their SNPV possessed the highest EFII compared to the other two kinds of factories. NOx EFs experienced lessen fluctuations than other pollutants among all the factories due to the different formation mechanism and no installation of NOx RFs. EFIII showed various fluctuations due to the different product types.

Speciated PM Composition and Gas and Particle Emission Factors for Diesel Construction Machinery in China

ABSTRACT On-board emission measurements were performed on nine diesel construction machines operated under real-world conditions in China. The emission factors (EFs) for NOx, CO, the total hydrocarbons, PM, and the particle number concentration were determined under actual operating conditions, i.e., during idling, moving, and working. To investigate the chemical composition of PM from diesel machinery, organic carbon (OC), containing particulate organic matter (POM); elemental carbon (EC); water-soluble ions (WSIs); and elements were also analyzed herein. OC was the most abundant component (contributing 39.3 ± 11% of the mass), followed by EC (37.7 ± 13%). POM species, including n-alkanes, hopanes, polycyclic aromatic hydrocarbons (PAHs), and n-fatty acids, contributed approximately 2.4–6.4% of the total PM mass. Compounds with 3 or 4 aromatic rings, including pyrene, phenanthrene, and fluoranthene, dominated the particulate PAHs, accounting for 62% of the total mass. These results are consistent with those of previous studies and can help to minimize uncertainties in emission inventories and source apportionment for non-road machinery.

Chemical Characterization of Fine Particulate Matter in Gasoline and Diesel Vehicle Exhaust

ABSTRACT This study investigated the chemical composition (carbonaceous species, water-soluble ions and metal elements) of fine particulate matter (PM2.5) emitted by gasoline and diesel vehicles. The emission factors of PM2.5, total hydrocarbons (THC), carbon monoxide (CO) and oxides of nitrogen (NOx) were also determined. The emission measurements were performed for four gasoline and four diesel vehicles on a dynamometer with a constant volume sampling system. Vehicles having larger engines and higher accumulated mileages had higher emission factors of gaseous pollutants. Moreover, the average emission factor of NOx was about 30 times higher for diesel vehicles than for gasoline vehicles. The average PM2.5 emission factors for gasoline and diesel vehicles were 1.57 mg km–1 and 57.8 mg km–1, respectively. The ratio of organic carbon to elemental carbon (OC/EC) was found to be a good indicator of gasoline vehicle emissions (OC/EC > 1) and diesel vehicle emissions (OC/EC < 1). Among water-soluble ions, Ca2+ and SO42– had the highest contribution to PM2.5 emitted by gasoline vehicles, while NO3–, SO42– and Ca2+ had the highest contribution to PM2.5 emitted by diesel vehicles. Na, Ca, Fe and Zn were the top four metal elements in terms of their contributions to PM2.5 mass for both types of the vehicles, while Cd, Cr, Pb and Sb were some of the toxic metal elements detected in PM2.5.

Effects of Retarding Fuel Injection Timing on Toxic Organic Pollutant Emissions from Diesel Engines

ABSTRACT Retarding the fuel injection timing is an effective strategy for controlling NOx emissions from diesel engines. However, the influence of retarding the fuel injection timing on polycyclic aromatic hydrocarbon (PAH) and persistent organic pollutant (POP) emissions has not yet been investigated. In this study, the diesel engine was tested using four of the existing thirteen European steady state cycle (ESC) modes. The fuel injection timing was retarded from –8° to –6° and the diesel exhaust gas samples were analyzed for PAH and POP emissions. The NOx emission factor reduced by ~25% when the fuel injection timing was retarded. However, the strategy had a negative effect on combustion efficiency. The carbon monoxide (CO) and particulate matter (PM) emissions were 1.4 and 1.2 times higher for the –6° scenario, respectively. The emission factors of all the toxic organic pollutants increased drastically when the fuel injection timing was retarded. For instance, the emission factors of PAH and polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) for the –6° scenario, based on BaPeq and WHO-TEQ, were 22 and 10 times higher than for the –8° scenario. The retardation had more influence on these pollutants in the particle-phase than in gas-phase. The resultant negative impact on combustion increased the emissions of products of incomplete combustion, enhancing the potential of POP formation via de novo synthesis. The study concludes that although retarding the fuel injection timing leads to a decrease in NOx emissions from diesel engines, it also results in an increase in PAH and POP emissions.