Heavy Diesel Vehicles Research Articles

Study on Emission Characteristics of Heavy Duty Diesel Vehicle in Plateau Environment

In order to understand the emission characteristics of National VI heavy-duty diesel vehicles on long slopes under full load in plateau environment, an N3 heavy-duty diesel vehicle was tested on actual road emissions to study the instantaneous emissions of pollutants from heavy-duty diesel vehicles on long uphill and downhill slopes and compare their emission factors. The results show that the engine exhaust temperature decreases with the decrease of altitude. When heavy diesel vehicles are going uphill, with the increase of road slope, NOx emissions show a downward trend and PN emissions show an upward trend. However, when heavy diesel vehicles go downhill, with the decrease of road slope, NOx emissions show an increasing trend and PN emissions show a decreasing trend. When heavy diesel vehicles go uphill, the pollutant emission is worse than that when they go downhill.

Air Quality Assessment along China-Pakistan Economic Corridor at the Confluence of Himalaya-Karakoram-Hindukush

Recently, analyses of the air quality in Pakistan have received significant interest, especially regarding the impact of air pollutant concentrations on human health. The Atlas of Baseline Environmental Profiling along the China-Pakistan Economic Corridor (CPEC) at five locations in Gilgit-Baltistan (GB) is a major landmark in this regard due to the presence of massive glaciers in the region, which are considered as water reserves for the country. Using various statistical measurements, the air quality was analyzed at the studied geographic locations. Further, air quality was evaluated based on air pollutant data acquired from ambient air monitoring laboratories. For example, 24 h concentrations of particulate matter (PM2.5) were found to range from 25.4 to 60.1 µg/m3, with peaks in the winter season at Gilgit. It was found that PM2.5 values were 1.7 and 1.3 times greater than National Environmental Quality Standards (NEQS) standards only at Gilgit and Chilas, respectively, and 1.5 to 4 times greater than the World Health Organization (WHO) standards at all locations. Similarly, PM2.5 concentrations were found to range from 31.4 to 63.9 µg/m3, peaking at Chilas in summer 2020. The observed values were 1.1 to 1.8 times and 2 to 4.2 times greater than the NEQS and WHO standards, respectively, at all locations. In addition, the average peaks of black carbon (BC) were measured at Gilgit, both in winter (16.21 µg/m3) and summer (7.83 µg/m3). These elevated levels could be attributed to the use of heavy diesel vehicles, various road activities and different meteorological conditions. Pollutants such as carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOX) and ozone (O3) were found to be within NEQS and WHO limits. Based on air quality metrics, the effect of PM2.5 on air quality was found to be moderate in Sost, Hunza and Jaglot, while it was at unhealthy levels at Gilgit and Chilas in the winter of 2019; moderate levels were observed at Sost while unhealthy levels were detected at the remaining locations in the summer of 2020. There are no specific guidelines for BC. However, it is associated with PM2.5, which was found to be a major pollutant at all locations. The concentrations of CO, SO2 and O3 were found to be at safe levels at all locations. The major fraction of air masses is received either locally or from transboundary emissions. This study demonstrates that PM2.5 and BC are the major and prevailing air pollutants within the study region, while other air pollutants were found to be within the permissible limits of the WHO and NEQS.

Changes and Potential Sources of Atmospheric Black Carbon Concentration in Shanghai over the Past 40 Years Based on MERRA-2 Reanalysis Data

As an important component of atmospheric aerosols, black carbon (BC) has a great influence on the regional and global radiation balance, climate, and human health due to its small particle size, large specific surface area, and radiative forcing potential. Here, the spatio-temporal characteristics of atmospheric BC were investigated based on modern-era retrospective analysis for research and applications version 2 (MERRA-2) reanalysis data and ground observation data during 1980-2019 in Shanghai, a highly urbanized city in mainland China. The influences of local emissions and regional transmission on regional-scale BC concentrations were examined using the M-K trend test, backward trajectory analysis, and the potential source contribution function (PSCF). The results showed that:① MERRA-2 BC and ground observation datasets showed good consistency (R∈[0.68, 0.72]), indicating that MERRA-2 reanalysis data can be used to reveal long-term changes in ground-level atmospheric BC concentrations; ② Atmospheric BC concentrations in Shanghai over the past 40 years can be divided into three stages:a "low value" stage of slow growth[1980-1986, (1.75±0.17) μg·m-3], a relatively stable "median value" stage[1987-1999, (2.18 ±0.07) μg·m-3], and a fluctuating "high value" stage[2000-2019, (3.07±0.31) μg·m-3]. Seasonally, Shanghai's BC concentrations generally show a "U" pattern with low concentrations in summer and high concentrations in winter. As a result of black carbon emissions from marine diesel engines and other engines used for water transportation, a small peak also occurs in July; ③ The diagnostic quality ratio of air pollutants and the bivariate correlation analysis[R(BC-NO2)>R(BC-CO)>R(BC-SO2)] indicated that traffic emissions were the main sources of atmospheric BC in Shanghai, especially by heavy diesel vehicles; ④ The backward trajectory and PSCF analyses found that the air mass of Shanghai in summer was dominated by a clean sea breeze, accounting for 77.18%. In contrast, during the other seasons, more than 50% of the air mass came from the north. The potential source regions of atmospheric BC in Shanghai are mainly distributed in eastern China, expanding outwards and centering on the Yangtze River Delta, and the expansion direction is consistent with the directions of the backward trajectories.

Research on the Situation of In-use Consistency of China V Heavy Diesel Vehicles in Shenzhen

In order to explore the current status of in-use compliance of China V heavy-duty diesel vehicles in Shenzhen, five China V heavy-duty diesel vehicles were tested for NOX emissions using the LugDown cycle, and CO, NOX, and PM emissions were tested for these vehicles using the Portable Emissions Measurement System (PEMS).The test results showed that all 5 vehicles meet the NOX limit requirements of the LugDown test method, and 2 vehicles exceeded the limit requirements of the PEMS test method. For 3 vehicles below the PEMS test NOX limit, the difference in the average value of the two test methods was 14%-18%, and the median difference was 1%-63%; For the two vehicles that exceeded the PEMS test NOX limit, the average difference was 32%-63%, and the median difference was 81%-127%. For vehicles with higher NOX emissions, the LugDown test was not able to reflect the actual situation of real driving emission well. The particulate emission test results showed that the difference in the removal efficiency of different diesel particulate filter could reach more than 113 times, and the difference in the technology of cleaning in engine could reach more than 6 times. The study showed that the current status of compliance of in-use China V standard heavy-duty diesel vehicles was not optimistic.

Morphology and composition of particles emitted from conventional and alternative fuel vehicles

Size, morphology, and composition of airborne particles strongly affect human health and visibility, precipitation, and the kinetic characteristics of particles. In this study, the morphology and chemical composition of particles emitted from conventional (diesel and gasoline) and alternative (CNG and methanol) fuel vehicles were characterized through scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX). The SEM images revealed that the size of primary particles (without agglomeration) was approximately 10 nm in the exhaust from all the tested vehicles. The particles emitted from gasoline vehicle (GV), CNG vehicle (CNGV), and methanol vehicle (MV) had the same median diameter, 62 nm, which was smaller than those from heavy diesel vehicle (HDV) and light diesel vehicle (LDV). Soot was observed in the HDV, LDV, and GV samples but not in the CNGV and MV. The fractal dimension, which was used to quantify the degree of irregularity of soot, was 1.752 ± 0.014, 1.789 ± 0.076, and 1.769 ± 0.006 in the exhaust from HDV, LDV, and GV samples, respectively. The particles discharged by all tested vehicles contained the elements C, O, Fe, and Na. The main element in the samples of HDV, LDV, and GV was C, while O was the main element in the samples of alternative fuel vehicles. The profiles of minor elements were more complex in the emissions of alternative fuel vehicles than those in the emissions of conventional fuel vehicles. The results improved our understanding of the morphology and elemental composition of particles emitted from vehicles powered by diesel, gasoline, CNG, and methanol.

Black carbon and PM2.5 monitoring campaign on the roadside and residential urban background sites in the city of Tehran

Fine particulate matter characterized as PM2.5 is the most important criteria air pollutant in the city of Tehran. Tehran is one of the most polluted cities of the Middle East based on annual mean PM2.5 concentrations. Tehran emission inventory shows the large contribution of mobile sources to the total particles. PM2.5 source apportionment studies show large fraction of black carbon (BC) in the total mass of PM2.5, especially during the cold seasons. BC is the product of incomplete combustion that is mainly derived from diesel engines and rich-burned gasoline carburetor engines on scooters and light-duty vehicles. The present study shows the results of a large experimental campaign in which BC concentration data along with PM2.5 mass concentration data were collected at various sites in the city of Tehran for a period of a year. The effect of heavy-duty diesel vehicle traffic on fresh BC and on the mass fraction of BC to PM2.5 was observed. Nearly 17% of total mass of PM2.5 was identified as BC. During the night hours the BC/PM2.5 mass ratio was increased to more than 4 times than that of day hours due to heavy-duty diesel traffic restrictions during the day. More detailed analyses based on absorption characteristics of BC showed that by increasing heavy diesel vehicle traffic during the night hours, more fresh BC was collected compared to that of aged BC collected during the day time. A city wide temporary ban of heavy-duty diesel traffic during an air pollution episode resulted in a sudden reduction of BC concentration in Tehran air, while the total mass of PM2.5 remained constant. This shows the direct contribution of diesel fleet to BC. It shows the necessity of introducing more accurate and relevant pollutant indicators such as BC mass instead of total PM2.5 mass for better and more effective policies.

Using a chassis dynamometer to determine the influencing factors for the emissions of Euro VI vehicles

In order to explore the influence of different factors on the emissions of heavy diesel vehicles, a chassis dynamometer was used to test and analyze a Euro VI standard heavy-duty diesel vehicle under different load, fuel, driving conditions, and resistance conditions. The full load condition was found to increase NOx emissions by about 0.107 g/km (30%) and the particulate matter (PM) by 0.003 g/km (18%) compared to the empty load condition. Compared with the China V diesel, the NOx emissions of the Beijing VI diesel were reduced by 0.065 g/km (18%), and PM decreased by 0.004 g/km (25%). The HC, CO, PM, and NOx emissions measured during the Chinese World Harmonized Transient Cycle (C-WHTC) were 0.002 g/km (27%), 0.0005 g/km (14%), 0.0024 g/km (15%), and 0.092 g/km (25%) higher, respectively, than those measured during the European Transient Cycle (ETC). The HC, CO, PM, and NOx emissions measured by using the test resistance were 0.002 g/km (28%), 0.001 g/km (25%), 0.003 g/km (18.7%), and 0.09 g/km (25.7%) higher, respectively, than those calculated with the recommended formula.

Tackling nitric oxide emissions from dominant diesel vehicle models using on-road remote sensing technology

Remote sensing provides a rapid detection of vehicle emissions under real driving condition. Remote sensing studies showed that diesel nitrogen oxides emissions changed little or were even increasing in recent years despite the tightened emission standards. To more accurately and fairly evaluate the emission trends, it is hypothesized that analysis should be detailed for individual vehicle models as each model adopted different emissions control technologies and retrofitted the engine/vehicle at different time. Therefore, this study was aimed to investigate the recent nitric oxide (NO) emission trends of the dominant diesel vehicle models using a large remote sensing dataset collected in Hong Kong. The results showed that the diesel vehicle fleet was dominated by only seven models, accounting for 78% of the total remote sensing records. Although each model had different emission levels and trends, generally all the dominant models showed a steady decrease or stable level in the fuel based NO emission factors (g/kg fuel) over the period studied except for BaM1 and BdM2. A significant increase was observed for the BaM1 2.49 L and early 2.98 L models during 2005–2011, which we attribute to the change in the diesel fuel injection technology. However, the overall mean NO emission factor of all the vehicles was stable during 1991–2006 and then decreased steadily during 2006–2016, in which the emission trends of individual models were averaged out and thus masked. Nevertheless, the latest small, medium and heavy diesel vehicles achieved similar NO emission factors due to the converging of operation windows of the engine and emission control devices. The findings suggested that the increasingly stringent European emission standards were not very effective in reducing the NO emissions of some diesel vehicle models in the real world.

Study on emission characteristics of biodiesel fuel for heavy diesel vehicles

This study uses the C-WTVC cycle to simulate the actual driving conditions of bus on the classic dynamometer to test the emission of vehicles with different fuels of Tier IV and V buses. The results showed that the NOx emission of Beijing VI diesel fuel blended with 5% biodiesel increased compared with the emission of pure diesel of Beijing VI, but the overall increase was not significant. The emission factors of CO, THC and PM the have been reduced. Heavy vehicles with Beijing-VI diesel fuel blended with 5% biodiesel did not change much in emissions and durability prior to endurance of 10,000 km.

Removal of Particulate Matter Emissions from a Vehicle Using a Self-Powered Triboelectric Filter.

Particulate matter (PM) pollution from automobile exhaust has become one of the main pollution sources in urban environments. Although the diesel particulate filter has been used in heavy diesel vehicles, there is no particulate filter for most gasoline cars or light-duty vehicles because of high cost. Here, we introduce a self-powered triboelectric filter for removing PMs from automobile exhaust fumes using the triboelectrification effect. The finite element simulation reveals that the collision or friction between PTFE pellets and electrodes can generate large triboelectric charges and form a space electric field as high as 12 MV/m, accompanying an open-circuit voltage of ∼6 kV between the two electrodes, which is comparable to the measured value of 3 kV. By controlling the vibration frequency and fill ratio of pellets, more than 94% PMs in aerosol can be removed using the high electric field in the triboelectric filter. In real automobile exhaust fumes, the triboelectic filter has a mass collection efficiency of ∼95.5% for PM2.5 using self-vibration of the tailpipe.

Five years of London’s low emission zone: Effects on vehicle fleet composition and air quality

This paper uses registration and enforcement information to assess the impact of London’s low emission zone on vehicle registrations, usage and air pollution. The zone was implemented in a staged process in 2008 to reduce the emissions of air pollutants of direct harm to human health. The zone targeted the worst polluters, specifically heavy diesel vehicles, buses and coaches by imposing minimum emissions standards on vehicles operating in an area covering most of Greater London. Several years on it remains unclear how successful the zone has been in meeting its stated objectives and what improvements in pollution levels can be attributed to the low emission zone. Results presented in this paper suggest the rate of fleet turnover for affected vehicle classes in London increased substantially when the zone was first introduced before returning to the national average in subsequent years. Early evidence for light commercial vehicles, which became subject to the scheme in early 2012, shows a similar effect is likely. Despite an overall growth in freight vehicles operating in London, the number of pre-Euro III vehicles has dropped and this has been coupled with a switch from rigid vehicles to light commercial vehicles and articulated vehicles. Ambient air quality measurements show concentrations of particulate matter within the low emission zone have dropped by 2.46–3.07% compared to just over 1% for areas just outside the zone. However, no discernible differences are found for NOX concentrations.

Association between light absorption measurements of PM2.5 and distance from heavy traffic roads in the Mexico City metropolitan area

To study the relationship between light absorption measurements of PM2.5 at various distances from heavy traffic roads and diesel vehicle counts in Mexico City. PM2.5 samples were obtained from June 2003-June 2005 in three MCMA regions. Light absorption (b abs) in a subset of PM2.5 samples was determined. We evaluated the effect of distance and diesel vehicle counts to heavy traffic roads on PM2.5 b abs using generalized estimating equation models. Median PM2.5 b abs measurements significantly decrease as distance from heavy traffic roads increases (p<0.002); levels decreased by 7% (CI95% 0.9-14) for each 100 additional meters from heavy traffic roads. Our model predicts that PM2.5 b abs measurements would increase by 20% (CI95% 3-38) as the hourly heavy diesel vehicle count increases by 150 per hour. PM2.5 b abs measurements are significantly associated with distance from motorways and traffic density and therefore can be used to assess human exposure to traffic-related emissions.

On-road ultrafine particle concentration in the M5 East road tunnel, Sydney, Australia

The human health effects following exposure to ultrafine (<100 nm) particles (UFPs) produced by fuel combustion, while not completely understood, are generally regarded as detrimental. Road tunnels have emerged as locations where maximum exposure to these particles may occur for the vehicle occupants using them. This study aimed to quantify and investigate the determinants of UFP concentrations in the 4 km twin-bore (eastbound and westbound) M5 East tunnel in Sydney, Australia. Sampling was undertaken using a condensation particle counter (CPC) mounted in a vehicle traversing both tunnel bores at various times of day from May through July, 2006. Supplementary measurements were conducted in February, 2008. Over three hundred transects of the tunnel were performed, and these were distributed evenly between the bores. Additional comparative measurements were conducted on a mixed route comprising major roads and shorter tunnels, all within Sydney. Individual trip average UFP concentrations in the M5 East tunnel bores ranged from 5.53 × 10 4 p cm −3 to 5.95 × 10 6 p cm −3. Data were sorted by hour of capture, and hourly median trip average (HMA) UFP concentrations ranged from 7.81 × 10 4 p cm −3 to 1.73 × 10 6 p cm −3. Hourly median UFP concentrations measured on the mixed route were between 3.71 × 10 4 p cm −3 and 1.55 × 10 5 p cm −3. Hourly heavy diesel vehicle (HDV) traffic volume was a very good determinant of UFP concentration in the eastbound tunnel bore ( R 2 = 0.87), but much less so in the westbound bore ( R 2 = 0.26). In both bores, the volume of passenger vehicles (i.e. unleaded gasoline-powered vehicles) was a significantly poorer determinant of particle concentration. When compared with similar studies reported previously, the measurements described here were among the highest recorded concentrations, which further highlights the contribution road tunnels may make to the overall UFP exposure of vehicle occupants.

Genotoxicity of air borne particulates assessed by comet and the Salmonella mutagenicity test in Jeddah, Saudi Arabia.

Fine airborne respirable particulates less than 10 micrometer (PM10) are considered one of the top environmental public health concerns, since they contain polycyclic aromatic hydrocarbons (PAHs) which are among the major carcinogenic compounds found in urban air. The objective of this study is to assess the genotoxicity of the ambient PM10 collected at 11 urban sites in Jeddah, Saudi Arabia. The PM10 extractable organic matter (EOM) was examined for its genotoxicity by the single cell gel electrophoresis (SCGE) comet assay and the Salmonella mutagenicity (Ames) test .Gas chromatography-mass spectrometry was used to quantify 16 PAH compounds in four sites. Samples from oil refinery and heavy diesel vehicles traffic sites showed significant DNA damage causing comet in 20-44% of the cells with tail moments ranging from 0.5-2.0 compared to samples from petrol driven cars and residential area, with comet in less than 2% of the cells and tail moments of < 0.02. In the Ames test, polluted sites showed indirect mutagenic response and caused 20-56 rev/ m3, mean while residential and reference sites caused 2-15 rev /m3. The genotoxicity of the EOM in both tests directly correlated with the amount of organic particulate and the PAHs concentrations in the air samples. The PAHs concentrations ranged between 0.83 ng/m3 in industrial and heavy diesel vehicles traffic sites to 0.18 ng /m3 in the residential area. Benzo(ghi)pyrene was the major PAH components and at one site it represented 65.4 % of the total PAHs. Samples of the oil refinery site were more genotoxic in the SCGE assay than samples from the heavy diesel vehicles traffic site, despite the fact that both sites contain almost similar amount of PAHs. The opposite was true for the mutagenicity in the Ames test. This could be due to the nature of the EOM in both sites. These findings confirm the genotoxic potency of the PM10 organic extracts to which urban populations are exposed.

Volatile organic compounds inside urban tunnels of São Paulo City, Brazil

Volatile organic compounds, such as oxygenated hydrocarbons, aliphatic and aromatic hydrocarbons were measured in ambient air from two distinct urban tunnels in Sao Paulo City, Brazil, in special, at rush hours. In these tunnels, traffic jams with significant numbers of vehicles with inadequate emission controls are frequent. Sao Paulo, a highly polluted city, has an unconventional mix of vehicle types in that a variety of gasoline blends, including oxygenated ones are used. Inside and outside tunnel measurements were performed to evaluate pollutant levels originated from direct vehicular emissions and formed by atmospheric photochemistry. Formaldehyde/acetaldehyde ratios of tunnel (A) circulating only light-duty vehicles fueled mainly with gasohol, a mixture containing 78-80% (v/v) gasoline and 20-25% ethanol, were < 1; ratios of tunnel (B) circulating light-duty vehicles fueled mainly with gasohol and heavy diesel vehicles, were approximately equal to 1. Formic acid/acetic acid ratios of both tunnels were much lower than 1. Benzaldehyde was suggested as a possible tracer of light-duty gasohol vehicular emissions. n-alkanes were the most abundant compound class (similar levels in both tunnels) followed by carbonyl compounds (higher levels in B), and aromatics compounds (higher levels in A). Organic acids, the minor species, were found at similar levels in both tunnels. Results of this survey show that toxic pollutants are present at significant levels in both tunnels. Formaldehyde and benzene, human carcinogenic agents, presented maximum mixing ratios of 39.2 and 24.8 ppbv, respectively, inside tunnel A; acetaldehyde, a probable human carcinogenic, reached a maximum of 34.5 ppbv inside tunnel B. Since vehicle occupants that spend a significant time in urban tunnels are commonly exposed to toxic pollutant emissions, future extensive studies should be done in order to estimate exposure levels of toxic ambient air pollutants for these people.

Effects of reduction of NOx on the NO2 levels in urban streets

Nitrogen dioxide is a major problem in urban areas. Persons suffering from respiratory diseases, especially asthma patients, are sensitive to NO2 at high concentrations. Nitrogen oxide emissions from private cars have decreased due to the introduction of catalysts. However, the catalyst technique is today limited to petrol vehicles. Since heavy diesel vehicles, e.g. buses, contribute significantly to the NOx emissions, this will limit the reduction in emissions in many urban streets. Another factor is the continued increase in the car fleet in all countries. Most of the NOx from traffic is emitted as NO, which is thought to be harmless. NO is rapidly transformed to NO2 by a reaction with ozone in the air. Tropospheric ozone levels have been increasing in Europe for many years as a consequence of increasing pollution. Ozone in Danish streets is seen to be the limiting factor for the production of NO2. Thereby O3 is also the limiting factor for the NO2 levels in the streets. In this paper the above will be supported both by observations from the Danish air quality measurement programmes and by model simulations with the Danish Operational Street Pollution Model.