Characterization of exhaust particulates from diesel engine (original) (raw)
Related papers
2011
We report the first in situ size-resolved density measurements of particles produced by premixed charge compression ignition (PCCI) combustion and compare these with conventional diesel exhaust particles. The effective densities (F eff) of sizeclassified particles were determined by measurements with a differential mobility analyzer (DMA) and an aerosol particle mass analyzer (APM). Particle inherent densities (F i) were calculated using an expression for particle mass given by idealized aggregate (IA) theory, transmission electron microscopy (TEM) measurements of primary particle diameter (d pp), and a comparison of the measured number of particles in each size class with that predicted by a proposed DMA-APM response function for aggregates. The F eff of PCCI and conventional diesel particles were similar over a range of diameters characteristic of their number-size distributions. The F eff were 0.89, 0.58, and 0.51 g/cm 3 for conventional diesel and 0.90, 0.62, and 0.42 g/cm 3 for PCCI particles with 50, 100, and 150 nm electrical mobility diameters (d m), respectively. The error associated with F eff was about one percent of each measurement. The lowest F eff were observed for exhaust gas recirculation (EGR) levels somewhat lower than that required for PCCI operation. The F i of 50 and 100 nm conventional diesel particles were 1.22 (0.14 and 1.77 (0.29 g/cm 3 , which is in good agreement with previously reported values. PCCI F i for these size classes did not differ significantly (1.27 (0.16 and 2.10 (0.20 g/cm 3), suggesting like amounts of adsorbed liquid hydrocarbons. In addition, for 150 nm particles, the PCCI and conventional F i were the same (2.20 (0.34 g/cm 3). Given the close density values, we expect that particulate emissions control with diesel particulate filters (DPFs) would not be adversely affected by PCCI particle physical properties.
Semi-volatile and particulate emissions from the combustion of alternative diesel fuels
Chemosphere, 2001
Motor vehicle emissions are a major anthropogenic source of air pollution and contribute to the deterioration of urban air quality. In this paper, we report results of a laboratory investigation of particle formation from four dierent alternative diesel fuels, namely, compressed natural gas (CNG), dimethyl ether (DME), biodiesel, and diesel, under fuelrich conditions in the temperature range of 800±1200°C at pressures of approximately 24 atm. A single pulse shock tube was used to simulate compression ignition (CI) combustion conditions. Gaseous fuels (CNG and DME) were exposed premixed in air while liquid fuels (diesel and biodiesel) were injected using a high-pressure liquid injector. The results of surface analysis using a scanning electron microscope showed that the particles formed from combustion of all four of the above-mentioned fuels had a mean diameter less than 0X1 lm. From results of gravimetric analysis and fuel injection size it was found that under the test conditions described above the relative particulate yields from CNG, DME, biodiesel, and diesel were 0.30%. 0.026%, 0.52%, and 0.51%, respectively. Chemical analysis of particles showed that DME combustion particles had the highest soluble organic fraction (SOF) at 71%, followed by biodiesel (66%), CNG (38%) and diesel (20%). This illustrates that in case of both gaseous and liquid fuels, oxygenated fuels have a higher SOF than non-oxygenated fuels.
Particulate Morphology and Toxicity of an Alcohol Fuelled HCCI Engine
SAE International Journal of Fuels and Lubricants, 2014
Homogeneous charge compression ignition (HCCI) engines are attracting attention as next-generation internal combustion engines mainly because of very low NO x and PM emission potential and excellent thermal efficiency. Particulate emissions from HCCI engines have been usually considered negligible however recent studies suggest that PM number emissions from HCCI engines cannot be neglected. This study is therefore conducted on a modified four cylinder diesel engine to investigate this aspect of HCCI technology. One cylinder of the engine is modified to operate in HCCI mode for the experiments and port fuel injection technique is used for preparing homogenous charge in this cylinder. Experiments are conducted at 1200 and 2400 rpm engine speeds using gasoline, ethanol, methanol and butanol fuels. A partial flow dilution tunnel was employed to measure the mass of the particulates emitted on a pre-conditioned filter paper. The collected particulate matter (PM) was subjected to chemical analyses in order to assess the amount of Benzene Soluble Organic Fraction (BSOF) and trace metals (marker of toxicity) using Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES). Field emission scanning electron microscope (FE-SEM) was used for particulate morphology investigations at 1000X and 5000X resolution. Trace amount of particulates were observed on the filter paper for the test fuels. The concentration of different trace metals analyzed also showed decreasing trends with increasing engine loads.
Metal Particle Emissions in the Exhaust Stream of Diesel Engines: An Electron Microscope Study
Environmental Science & Technology, 2013
Scanning electron microscopy and transmission electron microscopy were applied to investigate the morphology, mode of occurrence and chemical composition of metal particles (diesel ash) in the exhaust stream of a small truck outfitted with a typical after-treatment system (a diesel oxidation catalyst (DOC) and a downstream diesel particulate filter (DPF)). Ash consists of Ca-Zn-P-Mg-S-Na-Al-K-phases (lube-oil related), Fe, Cr, Ni, Sn, Pb, Sn (engine wear), and Pd (DOC coating). Soot agglomerates of variable sizes (<0.5−5 μm) are abundant upstream of the DPF and are ash-free or contain notably little attached ash. Post-DPF soot agglomerates are very few, typically large (>1−5 μm, exceptionally 13 μm), rarely <0.5 μm, and contain abundant ash carried mostly from inside the DPF. The ash that reaches the atmosphere also occurs as separate aggregates ca. 0.2−2 μm in size consisting of sintered primary phases, ca. 20−400 nm large. Insoluble particles of these sizes may harm the respiratory and cardiovascular systems. The DPF probably promotes breakout of large soot agglomerates (mostly ashbearing) by favoring sintering. Noble metals detached from the DOC coating may reach the ambient air. Finally, very few agglomerates of Fe−oxide nanoparticles form newly from engine wear and escape into the atmosphere.
The characterisation of diesel exhaust particles – composition, size distribution and partitioning
Faraday Discuss., 2016
A number of major research questions remain concerning the sources and properties of road traffic generated particulate matter. A full understanding of the composition of primary vehicle exhaust aerosol and its contribution to secondary organic aerosol (SOA) formation still remains elusive, and many uncertainties exist relating to the semi-volatile component of the particles. Semi-Volatile Organic Compounds (SVOCs) are compounds which partition directly between the gas and aerosol phases under ambient conditions. The SVOCs in engine exhaust are typically hydrocarbons in the C15–C35 range, and are largely uncharacterised because they are unresolved by traditional gas chromatography, forming a large hump in the chromatogram referred to as Unresolved Complex Mixture (UCM). In this study, thermal desorption coupled to comprehensive Two Dimensional Gas-Chromatography Time-of-Flight Mass-Spectrometry (TD-GC × GC-ToF-MS) was exploited to characterise and quantify the composition of SVOCs f...
Engineering and Technology Journal, 2019
Understanding the size and morphological properties of particulate matter (PM) is essential to improve analysis of the process of PM formation in diesel engines. These will help to reduce undesirable environmental impact and health effects. A scanning mobility particle sizer (SMPS) and thermal gravimetric analysis (TGA) were used to study the changes in size characteristics of PM/soot and soot reactivity. Furthermore, improve the oxidation of soot particles in diesel engines is necessary under the range of different fuel combustions. Oxygenated fuels (e.g., ethanol blend, E10 and butanol blend, B16) were used in this experimental study to show how insignificant changes in morphological characteristics and activity of PM. The oxidation and activation energy of PM was achieved at the lower temperature from the combustion of oxygenated fuels compared with diesel fuel combustion. Besides, it was found that both the size of soot particulate and the number of primary particles are reduced with increasing the oxygen content in oxygenated fuels than the diesel fuel. The shape of primary soot particle for PM is a bit more spherical in the case of diesel fuel than to the oxygenated fuels.
Journal of Aerosol Science, 2014
Regional deposition of diesel particles in the human lungs was analyzed and the chemical composition of inhaled particles was investigated. The off-road diesel engine with a diesel particulate filter (DPF) or a selective catalytic reduction (SCR) unit and without any exhaust after-treatment system was used. Around 85-95% of the measured particles were of ultrafine size and 53-84% of those nanoparticles. Over 70% of the deposited particles under 0.1 mm and about 45-70% of the deposited particles from 0.1 to 1 mm reach also the alveolar-interstitial level. Elements analyzed in particles were C,
Composition of Semi-volatile Particles from Diesel Exhaust
SAE Technical Paper Series, 2005
Vehicle exhaust particles from diesel passenger vehicles were studied in terms of volatility and chemical composition. Condensation of semi-volatile compounds leads to particle growth during exhaust dilution and cooling. The particle growth was observed to be particle surface related. At higher vehicle speed and load some of the semi-volatile material forms nucleation particles that are dominating the particle number concentration. The nucleation mode is completely volatile at 180°C and consists mainly of sulfate. The amount of organic material is smaller. The organics/sulfate ratio is larger for the soot mode indicating an earlier condensation process of organics before they are incorporated in the nucleation process. Under typical atmospheric dilution conditions most of the semi-volatile material is present in the soot mode. The semi-volatile material evaporates at temperature between 130°C and 180°C. Thermal treatment using a thermodenuder enables complete evaporation of the nucleation particles, however not all material from the soot particles is removed.