Influence of Diesel Fuel Sulfur on Nanoparticle Emissions from City Buses (original) (raw)
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Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 2017
High-sulphur and medium-sulphur diesel fuels are still used in several countries. Although diesel particulate filter technology for on-road diesel engines has existed since 1989, the availability of high-sulphur and medium-sulphur diesel fuels in the market causes delays in the use of catalysed filter technologies. However, the situation in places such as Tehran is considered unhealthy because of particles and black carbon, and full distribution of ultra-low-sulphur diesel is awaited eagerly. The purpose of this study is to investigate the effect of the sulphur content in fuels on the gaseous and solid exhaust emissions of a 220 kW Euro II engine equipped with a sintered metal active–passive filter, focusing on the regeneration phenomenon. The results show that the efficiency for filtering the maximum number of particles was 99.9% and that the average was above 99% for steady-state operating conditions for both high-sulphur diesel (7700 ppm) and medium-sulphur diesel (229 ppm). The ...
Particles emitted during the stops of an urban bus fuelled with ethanol–biodiesel–diesel blends
Urban Climate, 2012
Urban buses with diesel engines produce NOx and particulate matter emissions thus affecting local city pollution. During stops, due to traffic lights, programmed stops, etc., pollutants are emitted close to people, being damaging to their health. This paper studies the effects on particle size distributions caused by the use of oxygenated fuels during stops of an urban bus. Fuels used are a blend of ethanol and diesel (denoted as ED) and a blend of ethanol, biodiesel and diesel (denoted as EBD), which are compared to a diesel fuel used as reference. Tests were carried out on a vehicle under real working conditions in the Spanish city of Seville. A Horiba 1300 on-board system (OBS) was used to measure operating conditions, and an Engine Exhaust Particle Sizer Spectrometer was used to determine particle size distributions. Results showed a reduction in the number concentration of accumulation mode when oxygenated fuels were used. However, they produced a slight increase in the nuclei mode, as well as a reduction in particle diameters from both modes when using EBD blends, being more significant when referring to accumulation mode. These findings may be considered negative for the oxygenated blends under these operating conditions.
Investigation of ultrafine particle formation during diesel exhaust dilution
Environmental science & technology, 1999
Measurements of the size distribution of particles emitted from a modern heavy duty diesel engine using fuel with a sulfur content of between 0.03 and 0.05% by mass have been made under constant engine operating conditions, but with variations in the humidity of dilution air and dilution ratio prior to particle size measurement. The results show clearly that the measured size distribution is crucially dependent upon the conditions of dilution, hence creating real difficulties for comparison of data between different investigators. Conditions of high dilution ratio and high relative humidity both tend to favor the production of nanoparticles, especially within the range below 50 nm diameter. Application of homogeneous nucleation theory shows that nanoparticle production during dilution is qualitatively consistent with the production of sulfuric acid, but the predicted nucleation rates are lower than those measured, in common with studies of nucleation in the atmosphere. Chemical analysis of size-fractionated particles shows enhancement of sulfate concentrations in humid dilution conditions and at high dilution ratios consistent with the above mechanism. The possible role of semivolatile organic compounds in these processes has not been investigated.
Volatile Nanoparticle Formation and Growth within a Diluting Diesel Car Exhaust
Journal of the Air & Waste Management Association, 2011
A major source of particle number emissions is road traffic. However, scientific knowledge concerning secondary particle formation and growth of ultrafine particles within vehicle exhaust plumes is still very limited. Volatile nanoparticle formation and subsequent growth conditions were analyzed here to gain a better understanding of "real-world" dilution conditions. Coupled computational fluid dynamics and aerosol microphysics models together with measured size distributions within the exhaust plume of a diesel car were used. The impact of soot particles on nucleation, acting as a condensational sink, and the possible role of low-volatile organic components in growth were assessed. A prescribed reduction of soot particle emissions by 2 orders of magnitude (to capture the effect of a diesel particle filter) resulted in concentrations of nucleation-mode particles within the exhaust plume that were approximately 1 order of magnitude larger. Simulations for simplified sulfuric acid-water vapor gas-oil containing nucleation-mode particles show that the largest particle growth is located in a recirculation zone in the wake of the car. Growth of particles within the vehicle exhaust plume up to detectable size depends crucially on the relationship between the mass rate of gaseous precursor emissions and rapid dilution. Chassis dynamometer measurements indicate that emissions of possible hydrocarbon precursors are significantly enhanced under high engine load conditions and high engine speed. On the basis of results obtained for a diesel passenger car, the contributions from light diesel vehicles to the observed abundance of measured nucleation-mode particles near busy roads might be attributable to the impact of two different time scales: (1) a short one within the plume, marked by sufficient precursor emissions and rapid dilution; and (2) a second and comparatively long time scale resulting from the mix of different precursor sources and the impact of atmospheric chemistry. IMPLICATIONS Volatile nucleation-mode particles still dominate curbside size distributions. In contrast to nonvolatile vehicle particle number emission factors, the formation of volatile curbside particle number concentrations depends on processes that cannot be reproduced on vehicle test benches in a reasonably economic way. Greater understanding of formation processes and subsequent growth, chemical composition, and the impact of volatile precursor mix is needed to properly evaluate health effects. An integrated approach is necessary when assessing emissions from different sources and measures.
The impact of sulphur content of diesel fuel on ultrafine particle formation
2003
Early this year the Australian Department of Environment and Heritage commissioned a desktop literature review with a focus on ultrafine particles including analysis of health impacts of the particles as well as the impact of sulphur content of diesel fuel on ultrafine particle emission. This paper summarizes the findings of the report on the link between the sulphur content of diesel fuels and the number of ultrafine particles in diesel emissions. The literature search on this topic resulted in over 150 publications. The majority of these publications, although investigating different aspects of the influence of fuel sulphur level on diesel vehicle emissions, were not directly concerned with ultrafine particle emissions. A specific focus of the paper is on: summary of state of knowledge established by the review, and summary of recommendations on the research priorities for Australia to address the information gaps for this issue, and on the appropriate management responses.
Many metropolitan transit authorities are considering upgrading transit bus fleets to decrease ambient criteria pollutant levels. Advancements in engine and fuel technology have lead to a generation of lower-emission buses in a variety of fuel types. Dynamometer tests show substantial reductions in particulate mass emissions for younger buses (<10 years) over older models, but particle number reduction has not been verified in the research. Recent studies suggest that particle number is a more important factor than particle mass in determining health effects. In-vehicle particle number concentration measurements on conventional diesel, oxidation-catalyst diesel and compressed natural gas transit buses are compared to estimate relative in-vehicle particulate exposures. Two primary consistencies are observed from the data: the CNG buses have average particle count concentrations near the average concentrations for the oxidation-catalyst diesel buses, and the conventional diesel buses have average particle count concentrations approximately three to four times greater than the CNG buses. Particle number concentrations are also noticeably affected by bus idling behavior and ventilation options, such as, window position and air conditioning.
Detailed study on the effect of nano-particle size on emission characteristics of diesel engine
Petroleum Science and Technology, 2019
This work examines the effect of particle size of silicon oxide (SiO 2) nanoparticle on the emissions characteristics of four-stroke, single cylinder water-cooled diesel engine fueled with neat diesel (D100). Silicon oxide as an additive in various particle-size of 10 nm and 20 nm is included to D100 and termed as D100SiO 2 10 and D100SiO 2 20. The experimental result proved that the CO and HC emissions are 3.3% and 3.7% lower for D100SiO 2 10 than D100 at 3.5 bar BMEP. SiO 2 nanoparticle further reduces CO and HC emissions by 3.2% and 2.6% correspondingly for D100SiO 2 20 than D100. The degree of NO x emission in D100 is 4.6% higher at 3.5 bar BMEP. When compared to D100, tailpipe NOx emission was found to be 1.7% and 2.6% lower when fueled with D100SiO 2 10 and D100SiO 2 20. In addition, the tailpipe smoke emission was found to be 0.7% lower when fueled with D100.
Effects of Gaseous Sulphuric Acid on Diesel Exhaust Nanoparticle Formation and Characteristics
Environmental Science & Technology, 2013
Diesel exhaust gaseous sulphuric acid (GSA) concentrations and particle size distributions, concentrations, and volatility were studied at four driving conditions with a heavy duty diesel engine equipped with oxidative exhaust after-treatment. Low sulfur fuel and lubricant oil were used in the study. The concentration of the exhaust GSA was observed to vary depending on the engine driving history and load. The GSA affected the volatile particle fraction at high engine loads; higher GSA mole fraction was followed by an increase in volatile nucleation particle concentration and size as well as increase of size of particles possessing nonvolatile core. The GSA did not affect the number of nonvolatile particles. At low and medium loads, the exhaust GSA concentration was low and any GSA driven changes in particle population were not observed. Results show that during the exhaust cooling and dilution processes, besides critical in volatile nucleation particle formation, GSA can change the characteristics of all nucleation mode particles. Results show the dual nature of the nucleation mode particles so that the nucleation mode can include simultaneously volatile and nonvolatile particles, and fulfill the previous results for the nucleation mode formation, especially related to the role of GSA in formation processes.
On-Road Measurement of Particle Emission in the Exhaust Plume of a Diesel Passenger Car
Environmental Science & Technology, 2003
Particle size distributions were measured under real world dilution conditions in the exhaust plume of a diesel passenger car closely followed by a mobile laboratory on a high speed test track. Under carefully controlled conditions the exhaust plume was continuously sampled and analyzed inside the mobile laboratory. Exhaust particle size distribution data were recorded together with exhaust gas concentrations, i.e., CO, CO 2 , and NO x , and compared to data obtained from the same vehicle tested on a chassis dynamometer. Good agreement was found for the soot mode particles which occurred at a geometric mean diameter of approximately 50 nm and a total particle emission rate of 10 14 particles km -1 . Using 350 ppm high sulfur fuel and the standard oxidation catalyst a bimodal size distribution with a nucleation mode at 10 nm was observed at car velocities of 100 km h -1 and 120 km h -1 , respectively. Nucleation mode particles were only present if high sulfur fuel was used with the oxidation catalyst installed. This is in agreement with prior work that these particles are of semivolatile nature and originate from the nucleation of sulfates formed inside the catalyst. Temporal effects of the occurrence of nucleation mode particles during steadystate cruising and the dynamical behavior during acceleration and deceleration were investigated.