Reduction Of Particulate Emissions Research Articles

Particle formation due to brake wear, influence on the people health and measures for their reduction: a review.

For achieving the desired vehicle speed, the IC engine is very important, while for further vehicle speed maintaining and adaptation to road conditions, the braking system is important. With each brake's activation, wear products are forming, which are very harmful to the environment, because they can contain heavy metals. The braking working parameters (initial speed and braking pressure) are beside the achieved temperature in contact par, the most responsible, for particle formation and their release into the air. The particles forming can be divided by size on coarse, fine, and ultrafine particles, and which were observed in the paper. However, the greatest accent was placed on coarse and fine particles. For the determination of the composition of wear products, most often, laboratory tests were used. Particle composition greatly depends on the composition of brake pads, which can consist of about 30 components, and where some of these components have very unfavourable effects on people's health. So today, many researches are focused on finding such composition for brake pads, which will wear as less as possible, without disturbing the basic tribological properties. The conclusion of this paper shows that the applied materials for manufacturing the braking system are very important, as well as the construction, for the reduction of particle emission.

Soot Distribution and Thermal Regeneration of Marine Diesel Particulate Filter

Diesel particulate filter (DPF) is a leading technology reducing particle emissions from marine diesel engines. The removal or regeneration of soot in DPF is an important issue. The purpose of this study is to provide some reference strategies to design the DPF for marine diesel engines. In this paper, a mathematical model of a marine DPF was built up and the particle trap process and the regeneration dynamics were simulated. The results show that the cake soot mass concentrations from 0 to 4.2 g/L during the trap process increase linearly with the increase of the exhaust gas flows while the depth soot mass concentrations from 0 to 2.2 g/L firstly increase linearly and then keep constant. Soot is mainly concentrated in the front and rear portion of the filter and less soot is in the middle. The soot distribution in the cake and depth layers shows the unevenness during the trap and regeneration process. The initial soot loadings have great effects on pressure drops and soot mass concentrations before regeneration, but the little effect after regeneration. The exhaust gas temperature heated to 850 K can achieve 94% efficiency for the DPF regeneration. The heating rate has no effects on the pressure drops and soot mass concentrations, but the heating duration time of exhaust gas has an important impact on them.

Effect of injection parameters on combustion and emission characteristics under catalyst heating operation in a direct-injection spark-ignition engine

Clean and stable operation during the catalyst heating mode in a direct-injection spark-ignition engine is crucial to meet increasingly stringent emission regulations. Although the injection strategy has a profound effect on both emission and combustion characteristics, the relative importance of various injection parameters is not well understood under catalyst heating operation. Consequently, a parametric sweep of injection timing, injection pressure, and a number of split injections was conducted to reveal the relative impact of each parameter on particulate emissions, unburned hydrocarbon emissions, and combustion characteristics. A single-cylinder research engine with a side-mounted multi-hole injector was used in the experiments. The fuel was injected during the early intake stroke with 2–4 split injections using 10 and 20 MPa of injection pressure. Retarding the injection timing had the most significant influence on the accumulation-mode particulate emission. However, combustion stability can deteriorate if the injection timing is retarded beyond a certain point, possibly because of unfavorable fuel distribution near the spark plug. The higher number of split injections and/or injection pressure also contributed to lower accumulation-mode particulates. However, the combination of higher injection pressure and split numbers led to increased combustion variability due to the injector operating in a ballistic regime. The unburned hydrocarbon emissions were found to be insensitive to the injection parameters. Utilizing the parametric sweep results, it was hypothesized that the curtailment of the amount of fuel injected while the piston is located closer to the injector tip contributes to a lower fuel film on the piston surface and hence reduces engine-out particulate emissions. The estimation of fuel films using three-dimensional computational fluid dynamics confirmed that the hypothesis is valid under the catalyst heating operation used in this study. In the last step, the split ratio was varied such that the injection duration per injection increased gradually. Such a split ratio enabled further reduction of particulate emissions without incurring a penalty in unburned hydrocarbon emissions and combustion stability.

Physicochemical properties of exhaust soot from lower and higher alcohols: Characterizations and impact on soot oxidation behavior

Alcohol fuels can effectively reduce particle emissions of diesel engines. However, the effects of lower and higher alcohols on the microscopic physicochemical properties of the particles, such as the graphitization degree, surface aliphatic C–H functional groups, O/C ratio, and the carbon atom hybridization is still unclear. Moreover, the relationship between microscopic physicochemical properties and particle oxidation activity has not been systematically studied. Therefore, the alcohol-diesel mixtures with different carbon chain lengths and the same oxygen content were used as the fuel for commercial diesel engines in this research, such as methanol/diesel mixture (M10), n-butanol/diesel mixture (NB25), and n-octanol/diesel mixture (NO45), and the pure diesel (D100) was used as a reference. The physicochemical properties of different fuel particles under two loads were analyzed using Raman spectroscopy, Fourier Transform Infrared, and X-ray photoelectron spectroscopy. The results showed that as the load increased, the AD1/AG of the particles decreased, which meant that the graphitization degree increased. Moreover, the addition of alcohol fuel will increase the graphitization degree of the particles. In addition, the addition of alcohol fuel will reduce the aliphatic C–H functional groups and the O/C ratio on the surface of the particles. However, with the use of M10 to NO45, the aliphatic C–H functional groups continued to increase, while the O/C ratio first decreased and then increased, and the NB25 particle had the smallest O/C ratio. Through the Partial Least Square analysis, it was found that the fringe length and fringe separation distance had the most significant impact on the activation energy of the particles. Interestingly, among the characteristic parameters of Raman spectroscopy, the D1-full width at half maximum had the largest contribution to the activation energy.

Particle charging in electric field under simulated SO3-containing flue gas at low temperature

Particle and SO3 emitting from the processes of fuel combustion considerably deteriorate environment. Charging of particle in electric field was widely used for achieving effective removal of particle from SO3-containing flue gas in various industries. This study provided an insight into particle charging in electric field with presence of SO3 in terms of particle charging simulation and experiments under various conditions. Results illustrated that once temperature was below acid dew point, particle charge increased and then declined with the increasing concentration of SO3. Besides, sulfuric acid aerosol transformed from gaseous SO3 was enhanced by higher electric field strength and temperature, but this increase seemed to be limited when reached maximum. Meanwhile, electrode optimization could enhance charging by improving ion density, which charge of particle with 0.04 μm and 1.22 μm was increased by 3.53 and 1.16. Moreover, improving dielectric constant and electric field strength mainly acted on charging of larger particle, whereas improving ion density determined small particle charging. As for medium-sized particle, simultaneously combining electric field strength and ion density adjustment to enhance particle charging was effective. Find suggested that different parameter adjustment methods should be selected according to particle diameter to enhance particle charging and reduce particle emission of SO3-containing flue gas.

Effect of CCV and OCV System in Heavy Duty CNG Engine on the Particulate Emissions

<div class="section abstract"><div class="htmlview paragraph">Due to increasing pollution and climatic cries, newly implemented BS-VI emission norms in India have stressed the reduction of emission. For which many automobiles have been shifted to alternate fuels like CNG. Also, the Indian Automotive market is fuel economy cautious. This challenges to focus on improving fuel economy but without an increase in emissions. Crankcase blow-by gases can be an important source of particulate emission as well as other regulated and unregulated emissions. They can also contribute to the loss of lubricating oil and fouling of surface and engine components. Closed Crankcase Ventilation (CCV) or Open Crankcase Ventilation (OCV) is capable to reduce particulate emissions by removing the oil mist that is caused mainly due to blow-by in the combustion chamber. This paperwork is focused, to measure the effectiveness of the CCV and OCV systems on the engine-out emissions, primarily on the particulate emissions. A comparative analysis of these crankcase ventilation systems is made by monitoring various parameters, like engine speed, torque, crankcase pressure, engine blow-by, etc. to analyze the effectiveness of these systems for the reduction in particulate emissions.</div></div>

Oxymethylene Ethers: Quantifying the Effect of Fuel Chain Length and Water Emulsification on Emissions and Combustion in a Heavy-Duty Diesel Engine via Linear Regression Analysis

Due to the nature of diffusive combustion, diesel engines display a distinct trade-off between nitrogen oxide (NOX) and particulate matter (PM). Since emission regulations become ever stricter, the relevance of dissolving this trade-off increases steadily as it hinders engine development from achieving ultralow emission levels. Seeking new opportunities to approach the problem, the modification of fuel properties has gained much attention. In particular, oxygenated fuels reduce particle emissions drastically, while having little adverse impact on NOX. Similarly, water (H2O) emulsification of diesel is commonly reported to reduce both NOX and PM. Both methods appear very promising, yet only few investigations were conducted in an effort of combing the benefits of the two. With this work, the authors provide a detailed study on combustion and emissions for both neat oxymethylene ethers (OME2-OME5) and an H2O-emulsified OME mixture (OMEmix). By varying injection pressure and fuel properties (i.e., fuel chain length/H2O fraction in OMEmix) separately, the sole impact of altered fuel on the investigated measurands (NOX, carbon dioxide [CO2], combustion speed, cylinder pressure, heat release) could be distinguished and quantified on the basis of a linear regression analysis. It was found that the impact of fuel properties does not interact with varied operating conditions (i.e., rail pressure); thus the impact of altered fuel (chain length, H2O content) onto the measurands is nearly constant. With respect to NOX, the effect of increased fuel chain length (−0.73 g/kWhi with an increase in chain length of one) was found to be approximately twice as pronounced when directly compared with increasing H2O concentration (−0.41 g/kWhi with a 1% increase in H2O share). It was found that CO2 emissions are directly correlating to a rising fuel chain length (approx. +23 g/kWhi with an increase in chain length of one). The latter also affects the combustion process (i.e., combustion speed, max. heat release, max. cylinder pressure) in near-linear correlation. Contrary to the impact of neat OMEn chain length, an additional H2O share in OMEmix barely affected the combustion process.

Impact of carbon chain length of alcohols on the physicochemical properties and reactivity of exhaust soot

Particle is the main pollutant in diesel engine exhaust, which seriously endangers human health and the atmospheric environment. The use of alcohol fuels in diesel engines can effectively reduce particle emissions, but alcohol fuels with different carbon chain lengths will affect the generation process of particles, which in turn changes the physicochemical properties and oxidation characteristics of the particles. Therefore, it is particularly important to study the properties of particle emitted by diesel engines fueling alcohol fuels with different carbon chain lengths. The physicochemical properties of soot emitted from commercial diesel engines were studied by thermogravimetric analyzer, HRTEM (high-resolution transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy) in this paper, respectively. The diesel engine used alcohol-diesel blends of different carbon chain lengths with the same oxygen content as fuels, such as methanol/diesel blend (M10), n-butanol/diesel blend (NB25), and n-octanol/diesel blend (NO45), and pure diesel fuel was used as a reference. The results showed that the use of alcohols reduced the fractal dimension (Df) of particles, and the NB25 particles had the smallest Df. Moreover, the particles of blended fuels had smaller primary particle diameter (dp) compared to pure diesel. However, with the use of short-chain to long-chain alcohols, an increasing tendency of dp was observed. In terms of the nanostructure, as the use of short-chain to long-chain alcohols, the La (fringe length) increased, both the d (fringe separation distance) and Tf (fringe tortuosity) reduced, which was not favorable for the oxidation of the particles. In addition, in terms of oxygenated surface functional groups (SFGs), the CO group occupied a higher proportion in most working conditions relative to the groups of CO and COO. Further analysis showed that the dp and nanostructure had more influence on the oxidation behavior of soot than Df and oxygenated SFGs.

Particulate Emission Reduction by Fuel Injection Timing Optimization in a Gasoline Direct Injection Engine

Abstract Optimized fuel injection timings in internal combustion engines exhibit superior performance, combustion characteristics, and lower emissions. Particularly, particulate emissions from a gasoline direct injection (GDI) engines are highly dependent on fuel injection timings. GDI engines have emerged as a popular choice of power plants for automobiles among customers worldwide. They are preferred over multiple-port fuel injection (MPFI) engines in the transport sector because of their superior fuel economy and performance characteristics. The main objective of this study is to optimize a GDI engine for the lowest particulate emission at different fuel injection timings. GDI engine was investigated for particulate matter (PM) mass/particulate number (PN) emissions at five fuel injection timings (230, 250, 270, 290, and 310 deg bTDC), covering the entire envelope. Once the optimum fuel injection timing was determined, an engine exhaust particle sizer was used to measure the particle size-number distribution. Particulate samples from the engine were also collected on a filter paper for morphological investigations of particulates collected under optimized fuel injection timings. These experiments confirmed the importance and need to optimize the fuel injection timings at every engine operating point to reduce the PM/PN emissions from a GDI engine, which remains one of the biggest unresolved challenges to this technology.

Effect of n-butanol/diesel blends on performance and emissions of a heavy-duty diesel engine tested under the World Harmonised Steady-State cycle

In recent years, n-butanol produced from waste or lignocellulosic materials has become an attractive and sustainable green energy source for diesel engines because has a clear potential for the partial substitution of fossil-based diesel fuel. This study aims to analyse the effects of different n-butanol/diesel fuel blends on the performance and exhaust emissions of a Euro V heavy-duty diesel engine following the World Harmonised Steady-State Cycle (WHSC), as well as the effect of each mode on the test averaged results. The blends evaluated here were blends of conventional diesel fuel with 5%, 10% and 20% (by volume) n-butanol. Conventional diesel fuel was used as a reference fuel to compare the performance and emission characteristics of the different n-butanol blends. The main findings show that 10% butanol could be considered as a suitable proportion for blending n-butanol/conventional diesel owing to its favourable performance and reduction in particulate emissions, without significant changes in the gaseous emissions of NOX. Mode-by-mode comparative analysis results show improved engine performance with the use of n-butanol in most modes, regardless of speed or load conditions. CO emissions in general increase, despite the incorporation of n-butanol reduces CO emissions under high-load and low-speed conditions. THC emissions increase with n-butanol, being more critical under cold start conditions. The influence of n-butanol on NOX emissions does not have a clear trend, but it is observed that NO2 emissions decrease in all modes with the use of n-butanol blends, mainly in low load modes.

Experimental Investigation on Emissions Characteristics from Urban Bus Fueled with Diesel, Biodiesel and an Oxygenated Additive from Residual Glycerin from Biodiesel Production

The aim of the study was to assess the influence of the addition of an oxygenated additive (a mixture of mono-, di- and triacetylglycerol obtained from residual glycerin within the biodiesel production scheme) on the specific fuel consumption and exhaust emissions of a EURO 3 diesel bus during its daily route through the city. To do this, the urban bus was fuelled with five fuel blends of diesel (D), biodiesel (B), additive (A) and heptanol as co-surfactant (H). A portable emissions measurement system was used to measure the exhaust gases while an engine exhaust particle system with a dilution system, both installed on the urban bus, was used for nanoparticles measurement in actual operating conditions through the city of Seville. Results showed that B95A5 (95%v/v biodiesel, 5%v/v additive) and B90A10 were the blends that most increased NOx emissions (by 24.12% and 9.85%, respectively) compared to D100. On the other hand, B47.5D47.5A2.5H2.5 was the blend that most reduced total particle number (by 31.6%) and NOx emissions (by 12%). All in all, the oxygenated additive can be efficiently blended with biodiesel to reduce particle emissions from engines without diesel particle filter, such as those in urban buses in many European cities.

WLTC and real-driving emissions for an autochthonous biofuel from wine-industry waste

Residues from the wine industry constitute an abundant feedstock for biodiesel production in wine-producing countries. The use of grapeseed oil, together with bioethanol obtained from distillation of wine surplus or grape skins and stalks and wine lees, as reagents in the transesterification reaction, results in a mixture of fatty acid ethyl esters (FAEE), which is a fully renewable, autochthonous, and waste-derived biofuel. In this work, a blend of FAEE produced from grape seed oil with diesel fuel was selected based on a study of fuel properties, and the optimal blend, with 30% v/v of FAEE, was tested in a Euro 6 engine following the Worldwide harmonized Light-duty Test Cycle (WLTC) and a Real Driving Emissions Cycle (RDE), as required in the new certification procedures. Engine performance and emissions from this blend and a commercial diesel fuel were compared. The FAEE blend showed a significant potential to reduce particle emissions, both in mass and number (from 23% in number to 46.5% in mass for WLTC, and from 56% in number to 61% in mass for RDE), and CO (25.5% for WLTC and 39% for RDE) but penalized NOx (32% higher in WLTC and 26.4% higher in RDE).

Fuel Economy and Emissions of E85 in Passenger Cars - A Move towards Flex Fuel Vehicle

<div class="section abstract"><div class="htmlview paragraph">Many countries are developing strategies to curb the consumption of fossil fuels, and to increase the share of alternative fuels such as alcohols, natural gas, fuel cell and electricity in the energy pool in order to improve energy security and reduce atmospheric pollution. Alcohol fuels are promising one and it has been widely used in many countries as blending component for gasoline. Ethanol has a high-octane number but it has a lower calorific value than gasoline. The performance of engine may be affected with higher percentage of ethanol in gasoline due to demand for larger quantity of fuel that could not be supplied by vehicles which are tuned to run on gasoline only. In this study, a second electronic control unit (ECU) was installed in series with the existing commercial or primary ECU and an ethanol sensor was installed in the fuel line. This secondary ECU modulates the fuel injection pulse width of the primary ECU depending on ethanol concentration in the fuel. The vehicle studies were carried out using Indian automotive gasoline meeting IS:2796 specification and 85% ethanol blended gasoline (E85) in a climatically controlled chassis dynamometer lab in which test cell temperature maintained at 25±1 °C throughout the test. Modified Indian Driving Cycle tests (MIDC) and constant speed tests were carried out using E85 and commercial gasoline to investigate the fuel economy, gaseous mass emissions, particulate emission in terms number and size characteristics. Gaseous emission was reduced up to 30% with the penalty of reduction in fuel economy by approximately 30% over the MIDC. The vehicle power was maintained while using both fuels at respective constant speeds during the road load simulation cycles however an increase in fuel consumption was observed with E85. The tailpipe exhaust particle emission measurement had shown up to 50% reduction in exhaust particulate emissions with E85. This study demonstrates the potential of using higher blends of ethanol up to E85 and meeting power or speed demand at constant speeds and driving cycle tests.</div></div>

Effectiveness of battery electric vehicle promotion on particulate matter emissions reduction

Quantifying environmental benefits from battery electric vehicles (BEVs) requires an understanding of the long-term substitutional relationships among different vehicle technologies. This study analyzes how BEV promotion can contribute to reductions in particulate matter (PM) emissions in Korea and investigates effective long-term policy options. Using a choice model, this study simulates consumers’ vehicle replacement behavior under various policy scenarios from 2018 to 2025. The results show that BEV promotion alone has limited effectiveness at reducing PM emissions because BEV purchases were predominantly made by gasoline vehicle owners while diesel vehicles are the key source of emissions. This finding is significant because investment in BEV promotion in Korea specifies PM emissions reductions as their core objective and legal basis. Investigation of additional policy options suggests that the combination of direct regulations on diesel vehicles and a targeted rebate to promote substitution between diesel vehicles and BEVs can reduce PM emissions by ~13%.

Emission reduction process for the energetic use of biogenic residues

During the combustion of biogenic residues particulate matter, nitrogen oxides, chlorine and sulphur compounds as well as dioxins and furans occur in elevated concentrations depending on the respective fuel composition. Corresponding abatement technology is only available for the power plant sector and cannot be used economically on small biomass plants. Therefore an exhaust gas purification procedure was developed and tested which can be used economically in decentral biomass plants. The core of the exhaust aftertreatment process is a fabric filter with catalytically active filter bags which enables a combined reduction of dust and nitrogen oxides. An additional precoating of the fabric filter also removes acidic exhaust gas components such as SO2 and HCl. Experiments were conducted on pilot and field scale. Significant reduction of particle emissions, nitrogen oxides and chlorine compounds could be achieved. Further optimization of the quantities of reducing agent and precoat material supplied is necessary in order to improve the performance of the exhaust gas cleaning process.

Oxygen Transport Membranes for Efficient Glass Melting.

Glass manufacturing is an energy-intensive process in which oxy-fuel combustion can offer advantages over the traditional air-blown approach. Examples include the reduction of NOx and particulate emissions, improved furnace operations and enhanced heat transfer. This paper presents a one-dimensional mathematical model solving mass, momentum and energy balances for a planar oxygen transport membrane module. The main modelling parameters describing the surface oxygen kinetics and the microstructure morphology of the support are calibrated on experimental data obtained for a 30 μm thick dense La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) membrane layer, supported on a 0.7 mm porous LSCF structure. The model is then used to design and evaluate the performance of an oxygen transport membrane module integrated in a glass melting furnace. Three different oxy-fuel glass furnaces based on oxygen transport membrane and vacuum swing adsorption systems are compared to a reference air-blown unit. The analysis shows that the most efficient membrane-based oxyfuel furnace cuts the energy demand by ~22% as compared to the benchmark air-blown case. A preliminary economic assessment shows that membranes can reduce the overall glass production costs compared to oxyfuel plants based on vacuum swing adsorption technology.

Particulate matter emissions reduction from residential wood stove using inert porous material inside its combustion chamber

Residential wood stoves are the most important source of air pollution and particulate matter in southern regions of Chile, where the Eucalyptus globulus is the most consumed biomass. In this context, the main objective of this experimental investigation was to evaluate the effect of the use of inert ceramics foams (Silicon carbide) inside the combustion chamber of residential wood stoves on particulate matter emissions. The porous ceramics were disposed in three configurations (floor, walls, and roof) in a single-chamber, and biomass was burned. Preliminary wood stoves combustion test showed that porous ceramics increase firewood burning rates, exhaust gases and external surface temperatures, and carbon dioxide emissions. Final combustion test results showed that for all configurations the particulate matter emission factors decreased at least in 20%. Being the porous ceramics located at the combustion chamber walls the configuration with the highest improvement, achieving a 61% reduction. The positive effect, on biomass combustion, of adding porous ceramics inside the combustion chamber could be attributed to a higher rate of the volatile organic compounds being burned due to heat and mass transfer intensification. Thus, further studies are necessary to identify an optimal design for a combustion chamber incorporating porous ceramics.

Evaluating ignition propensity of high cycloparaffinic content alternative jet fuel by a chemical functional group approach

Abstract The molecular components typically found in today's jet fuels that meet ASTM specification are almost entirely alkanes and (mostly alkyl) aromatics with cycloalkyl contents seldom exceeding 40%. Aromatics and cycloalkyl contents are both important for achieving desirable jet fuel energy density, but it is well recognized that significant reductions in aircraft particulate emissions can be achieved by reducing fuel aromatic content (increasing hydrogen content). New jet fuels derived from non-petroleum and sustainable resources composed of much larger fractions of cycloalkanes spanning the entire molecular weight range are a potential path to maintaining high volumetric energy density even in the absence of aromatics. In this paper, the ignition characteristics of individual cycloalkanes of varying ring carbon number, alkyl side chain structure, and their mixtures with other molecular classes (n- and iso-alkanes) are investigated through experimentally determining their Derived Cetane Numbers (DCNs). The measurement reveals cycloheptane to have the highest DCN compared to other saturated cycloalkanes, which can be attributed to the conformal steric structure, previously discussed. A chemical functional group approach is extended to analyze chemical structural effects on the resulting DCN data and prior literature results by separately considering the roles of CH2 groups in cyclo ring, (CH2)cyclo, in comparison to CH2, (CH2)n, CH3, and benzyl-type groups utilized in the earlier work as chemical functional descriptors. A quantitative structure-property relationship (QSPR) regression model is constructed that well emulates the DCN database and is shown to predict a priori the DCN value of a recently proposed jet fuel composed mostly of cycloalkanes (Shell CPK POSF 13690) and a (previously studied) gas-to-liquid alternative jet fuel (Shell SPK POSF 5729). Feature sensitivity analyses show that the relative significance of (CH2)cyclo on determining DCN is substantially less than that derived from the cycloalkane side-chain structural properties. Finally, the ignition and sooting propensities of these two alternative jet fuels are discussed in a function of their blending ratios with petroleum-derived jet fuel.

Combustion phenomena affecting particle emission under boosting conditions in a turbocharged gasoline direct injection engine

As emission regulations for vehicles have become stricter, the survival of direct injection technologies has been threatened due to increased particle emissions. By many researchers, there has been the effort to reduce the particle emissions. Nonetheless, the sources of particle emissions from turbocharged gasoline direct injection engines (T-GDI) were still not investigated enough. In this research, the particle emission from a modern turbocharged gasoline direct injection engine was investigated through combustion analysis accompanying simultaneous flame visualization. The experiments were conducted under three load conditions from naturally-aspirated to highly boosted conditions. The start of injection was swept to identify the effect of fuel mixing processes and differed combustion phenomena by the fuel injections and the boosting on engines. As results, the boosting changed the influence of heterogeneity and flow interaction by sprays, resulting differences in heat release from combustion and particle generation. The boosting on engines suppressed the agglomeration of particles into large aggregate in half, but promoted the nucleation of particles become double compared to natural aspiration. With optimized injection systems, the most impacting factors are the control of spray interaction with in-cylinder flow and oxidation processes of particles. In the boosted conditions, the uncertain particle sources could occur, such as spontaneous ignitions by mixture stratification and biased flame propagation by flow interaction. Through optimization of injection strategies, the combustion phenomena can be controlled to reduce the particle emissions in the moderate boosted conditions. The results of combustion analysis affecting the particle generation can provide the clues to reduce particle emission from T-GDI engines.

Why Soot is not Alike Soot: A Molecular/Nanostructural Approach to Low Temperature Soot Oxidation

Due to worldwide increasingly sharpened emission regulations, the development of Gasoline Direct Injection and Diesel Direct Injection engines not only aims at the reduction of the emission of nitrogen oxides but also at the reduction of particulate emissions. Regarding present regulations, both tasks can be achieved solely with the help of exhaust after treatment systems. For the reduction of the emission of particulates, Gasoline (GPF) and diesel Particulate Filters (DPF) offer a solution and their implementation is intensely promoted. Under optimal conditions particulates retained on particulate filters are continuously oxidized with the exhaust residual oxygen so that the particulate filter (PF) is regenerated possibly without any additional intervention into the engine operating parameters. The regeneration behavior of PF depends on the reaction rates of soot particles with oxidative reactants at exhaust gas temperatures. The reaction rates of soot particles from internal combustion engines (ICE) often are discussed in terms of order/disorder on the particle nanoscale, the concentration and kind of functional groups on the particle surfaces, and the content of (mostly polycyclic aromatic) hydrocarbons in the soot. In this work the reactivity of different kinds of soot (soot from flames, soot from ICE, carbon black) under oxidation conditions representative for PF regeneration is investigated. Soot reactivity is determined in dynamic Temperature Programmed Oxidation (TPO) experiments and the soot primary particle morphology and nanostructure is investigated by High-Resolution Transmission Electron Microscopy (HRTEM). An image analysis method based on known methods from the literature and improving some infirmities is used to evaluate morphology and nanostructural characteristics. From this, primary particle size distributions, length and separation distance distributions as well as tortuosities of fringes within the primary particle structures are obtained. Further, UV–visible spectroscopy and Raman scattering and other diagnostic techniques are used to study the properties connected to the reactivity of soot and to corroborate the experimental findings. It is found that nanostructural characteristics predominantly affect reactivity. Oxidation rates are derived from TPO and interpreted on a molecular basis from quantum chemistry calculations revealing a replication/activation oxidation mechanism.