Academic literature on the topic 'Engine oil soot loading'

Recycling used plastic can help reduce the amount of plastic waste generated. Existing methods, namely the process of pyrolysis, are chemical heating processes that decompose plastics in the absence of oxygen. This decomposes the plastics in a controlled environment in order to produce fuel from waste. The present study consequently investigated the physical and chemical properties of pyrolysis oil derived from plastic bottle caps (WPBCO) and the effects on the engine performance and emission characteristics of a diesel engine operating on WPBCO. The experiments were conducted with a single-cylinder diesel engine operating at a constant 1500 rpm under various engine loading conditions. The experimental results of the chemical properties of test fuels indicated that WPBCO and diesel fuels have similar functional groups and chemical components. In comparison, WPBCO has a lower kinematic viscosity, density, specific gravity, flash point, fire point, cetane index, and distillation behavior than diesel fuel. However, WPBCO has a high gross calorific value, which makes it a suitable replacement for fossil fuel. In comparison to diesel fuel, the use of WPBCO in diesel engines results in increased brake-specific fuel consumption (BSFC) and brake thermal efficiency (BTE) under all load conditions. The combustion characteristics of the engine indicate that the use of WPBCO resulted in decreased in-cylinder pressure (ICP), rate of heat release (RoHR), and combustion stability compared to diesel fuel. In addition, the combustion of WPBCO advances the start of combustion more strongly than diesel fuel. The use of WPBCO increased emissions of NOX, CO, HC, and smoke. In addition, the particulate matter (PM) analysis showed that the combustion of WPBCO generated a higher PM concentration than diesel fuel. When WPBCO was combusted, the maximum rate of soot oxidation required a lower temperature, meaning that oxidizing the soot took less energy and that it was easier to break down the soot.

This paper investigates the power and emissions of Kubota RT125 diesel engines using biodiesel. It derived from rubber seed oil with variable mixing ratios of B0, B5, B10 and B20, with loading modes of 50%, 80%, 100%. This research was studied at velocity of 1600 rpm, 2000 rpm and 2400 rpm (revolution per minute). Simulation results from KIVA-3V software show that when the change from diesel (B0) to biodiesel (B5, B10, B20) the engine power does not change much, the amount of soot emission decreases dramatically while NOx increase, overall B20 fuel has the most similar results to diesel.

In a diesel engine the soot was produced due to the result of incomplete fuel combustion in the combustion chamber. Some of this soot moves down slowly to piston where the lubricant oil is located. This soot causes the lubricant oil to become contaminated thus increases its viscosity. As a result, frequent changing of lubricant oil is required in order to keep up the engine performance. This soot also has solid particles (Particulate Matter: PM) and nitrogen oxide (NOx) that are very harmful to the environment. The purpose of this study is to compare the opacity value of B20 (Jatropha) oil, Palm oil and diesel oil by using diesel engine. Besides that, this project also aims to compare the average of soot agglomeration size produces by using Jatropha oil, Palm oil and diesel oil in diesel engine. In this experiment, Jatropha and Palm oil was mixed with Diesel oil before being tested to diesel engine. A smoke tester was used to collect soot that came out from the exhaust of the diesel engine. The soot was observed by inverted microscope in order to investigate the soot agglomeration size. Result from this studies show that the value of opacity value of biodiesel Jatropha and Palm oil is lower compared to Diesel oil. Besides that, Diesel oil has the biggest soot agglomeration size compared to biodiesel.

Introduction. During the combustion of diesel fuel in a diesel engine with an increased fuel supply, as a result of its incomplete combustion, soot particles are formed, which are either released into the atmosphere or inevitably enter the engine oil. Soot, polluting the engine oil, causes a change in its quality indicators. Soot is very small particles formed by a complex reaction mechanism in the flame of a fuel-rich region during the combustion of hydrocarbons in the absence of air, mainly consisting of a mixture of amorphous carbon and organic matter.Materials and methods. This paper presents the results of a literary review aimed at studying the ways of soot occurrence during the operation of diesel engines, its effect. The mechanical properties of diesel soot are also discussed on the surfaces of friction pairs and engine components.Conclusions. The soot content in engine oil will increase sharply in engines with exhaust gas recirculation, which leads to an increase in temperature in the friction zones and viscosity of the lubricant, as well as to the formation of deposits on hot parts. These processes occur due to the discharge in the crankcase space and the intensification of the intake of gases from the combustion chamber. Oil change intervals should be monitored at an increased rate of soot entering the engine oil.Scope of the study / opportunity. This type of study will help determine the causes of soot in a diesel engine, understand the consequences of using engine oil contaminated with soot particles.Originality / value. The conducted research can be the basis for the development of recommendations for improving the maintenance of internal combustion engines for enterprises that have cars with diesel engines at their disposal in order to increase the resource of power units and reduce operating costs.

Soot particles are produced during combustion process in the diesel engine. These particles will later exhaust into the thermosphere and part of them will contaminate the engine oil. When the lubricant is contaminated with soot, diesel engine abrasion or in a worst-case scenario lubricant starvation occurs. This situation will eventually lead into engine ware. High volume of soot also raises acid level of the area. If this state co-occurs with high temperature of the engine and volatile gases during operation, engine corrosion may also be produced. This research study the effect of additive volume on the dispersion of soot in engine oil and effect of additive on size and volume of soot which affect to mechanism of ware in metal by tribology four-ball tester, image analysis by scanning electron microscope and particle size analysis by laser diffraction technique.

The paper presents the results of thermogravimetric tests of engine oil used in a small turbocharged spark-ignition engine. The main observation from the research was a significant soot contamination of engine oil, that appears even at its low mileage. This indicates that also in the case of port fuel injection spark-ignition engine, high particulate matter emissions may occur. It may therefore turn out that the small city car can be more harmful to the environment than much larger vehicles. A rapid soot contamination of the oil in this engine indicates as well that the oil change interval should be shortened.

The requirements set for engine oils are nowadays very high, varied, often contradictory and significantly go beyond the classic functions of engine oils. Also for the testing of engine oils, many different and advanced research methods are currently used. This arti-cle describes tests of fresh and used oil from a diesel engine using thermogravimetric analysis. This method was also used to determine the soot content of the used oil. The tests showed that the thermograms of fresh and used oil are similar, however in the oil used in the diesel engine the soot content increases.

Purpose The purpose of this paper is to identify the feature of soot in diesel engine oil and provide a method to stably disperse these soots using effect additives which is benefical for lubricants to pass related engine tests. Design/methodology/approach This paper designed experiments to investigate the dispersant type, treat level and different dispersant interactions which influence on lubricant soot-related viscosity increase. The research work developed an effective dispersant package which can well solve the soot-related viscosity increase, allowing pass Mack T-11 and Mack T-8 engine tests and demonstrated the helpfulness of using a quickly screening method developed by a steel piston diesel engine CA 6DL2-35. Findings The effect of dispersant treat level on the viscosity increase of the oil samples was negligible. Dispersant booster can effectively improve the soot handling ability of heavy-duty diesel engine oils (HDDEO), and the appropriate treat level of dispersant booster can help HDDEO pass Mack T-8 and Mack T-11 engine tests. Practical implications The test results are useful for formulators to select the appropriate dispersants or dispersant booster to develop the HDDEO packages which can meet the modern diesel engine lubrication requirements. Originality/value Most previous studies in this field were carried out on soot formation mechanism and soot-related wear rather than how to solve the soot-related viscosity increasing of HDDEO. This paper describes the soot dispersing requirements of different HDDEO specifications and developed an effective dispersant package which can well deal with Mack T-11 and Mack T-8E standard engine tests soot handling ability requirements.

Based on different fuel injection strategies, this paper analyzes the factors such as engine original emission smoke, exhaust temperature, soot content, wear spot diameter and kinematic viscosity. The study found that delaying injection timing, increased afterburn, engine original soot emissions, exhaust gas temperature increase, but will increase the thermal load of the parts. At the same time, the growth rate of lubricant soot and kinematic viscosity increased; The wear spot diameter at the same soot content is reduced, and the wear is reduced. In the end, the paper finally selects 1°CA BTDC as the optimal fuel injection strategy to achieve rapid aging of engine lubricating oil in order to complete the assessment of the anti-wear performance of lubricating oil.

Oil has an enormous influence on the condition of the engine. Determining its degradation allows companies to maximize the availability of a specific vehicle and fleet of vehicles in general. In the evolution of engine oil degradation, one of the variables considered to be the most important is soot content. This article examines the direction and severity of soot content and dispersion changes in engine oil occurring during actual engine operation during four complete change intervals. The oil under study was operated in a city bus. It belonged to the fleet of vehicles of a transport company from new to the mileage of about 200,000 km. Soot content was determined in accordance with ASTM E2412-10, while dispersion size was determined using the dried drop test in accordance with ASTM D7899. The results obtained provide the basis for the conclusion that the direction of change in soot content in each interval is characterized by a high degree of homogeneity. With respect to the degree of soot build-up, a high level of similarity was observed between the intervals studied. The study of change in the degree of oil dispersion using the “drop on blotter” method made it possible to confirm the trend of decreasing dispersion as the run increases. The obtained results led to the development of a statistical model describing these relationships.

The micellar self-assembly behaviour of a near-monodisperse linear poly(styrene-b-hydrogenated isoprene) (PS-PEP) diblock copolymer is examined in n-alkanes. Direct dissolution leads to formation of polydisperse colloidal aggregates that are kinetically frozen artefacts of the solid-state morphology. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies indicate that heating such copolymer dispersions up to 90 - 110oC gives well-defined spherical micelles that persist on cooling to 20oC. These observations are also consistent with small-angle X-ray scattering (SAXS) studies, which indicate the formation of star-like micelles in n-heptane and n-dodecane following a thermal cycle. Variable temperature 1H NMR studies in deuterated n-alkanes confirm partial solvation of the polystyrene micelle cores occurs on heating. Increased mobility of the core-forming polystyrene chains is consistent with the evolution in morphology via exchange of individual copolymer chains, as observed by DLS. Adsorption of this diblock copolymer onto a model colloidal substrate (carbon black) has been investigated using X-ray photoelectron spectroscopy (XPS). A Langmuir-type adsorption isotherm has been constructed using a supernatant depletion assay based on the aromatic chromophore in the polystyrene block. Comparable results were obtained using thermogravimetric analysis (TGA) to directly determine adsorbed amounts. Based on maximum adsorbed amounts at 20oC, these studies strongly suggest that individual copolymer chains adsorb onto carbon black from chloroform (a non-selective solvent), whereas micellar adsorption occurs from n-alkanes. This is important, because such copolymers are used as soot dispersants for engine oils. A near-monodisperse PS-PEP star diblock copolymer is examined in n-alkanes. Variable temperature 1H NMR studies using deuterated n-dodecane confirm that the outer polystyrene blocks are only partially solvated at 25oC, and solvation remains essentially constant on heating to 100oC. Physical adsorption of this copolymer onto carbon black is examined, with particular attention being paid to the effect of copolymer concentration on colloidal stability. Isotherms are constructed for copolymer adsorption onto carbon black at 20oC using a supernatant depletion assay based on UV spectroscopy analysis of the polystyrene aromatic chromophore. In addition, TGA is used to directly determine the amount of adsorbed copolymer on carbon black. Analytical centrifugation, optical microscopy (OM) and TEM studies indicate that the star copolymer acts as a flocculant for the carbon black particles at low concentration, with steric stabilisation observed above a certain solvent-dependent critical copolymer concentration. This is attributed to the spatial location of the polystyrene block, which enables copolymer adsorption onto multiple carbon black particles at low coverage, whereas all polystyrene ‘stickers’ adsorb onto single carbon black particles at high coverage, leading to steric stabilisation. SAXS is used to characterise copolymer-coated carbon black particles, providing complementary insights regarding changes in the fractal morphology that occur with increasing copolymer concentration. Moreover, SAXS also provided direct evidence for the presence of the copolymer chains at the particle surface. The effect of copolymer composition on both micelle diameter and dispersant performance (for carbon black particles) has been assessed for PS-PEP and poly(styrene-b-hydrogenated butadiene) diblock copolymers in n-dodecane. Direct dissolution at 20oC produces kinetically-frozen polydisperse aggregates, and higher polystyrene contents accentuate such an effect. Heating to 110oC produces relatively small, well-defined spherical micelles that persist on cooling to 20oC. Physical adsorption of these diblock copolymer micelles onto carbon black has been investigated by constructing Langmuir-type adsorption isotherms based on UV spectroscopy, which were also supported by TGA. Stokes’ law is used to calculate particle velocities in two very similar solvents (n-dodecane and d26-dodecane). Although each copolymer forms micelles with similar DLS and SAXS diameters, subtly different effective densities (0.92-1.02 g cm-3) are observed for the micelle-stabilised carbon black particles, which are substantially lower than the solid-state density of carbon black (1.89 g cm-3). Since the rate of sedimentation of sterically-stabilised carbon black particles depends on the density difference between the particles and the solvent, significant errors can be incurred in analytical centrifugation studies unless care is taken to determine accurate effective particle densities. Finally, the carbon black used in this project is assessed for its suitability as a mimic for diesel soot. Particle size, morphology, density and surface composition are assessed using BET surface area analysis, TEM, helium pycnometry and XPS. The extent of adsorption of a poly(ethylene-co-propylene) (dOCP) statistical copolymer or a PS-PEP diblock copolymer onto these two substrates is compared indirectly using a supernatant depletion assay based on UV spectroscopy. TGA is also used to directly determine the extent of copolymer adsorption. Degrees of dispersion are examined using OM, TEM and analytical centrifugation. SAXS reveals some structural organisation differences between carbon black and diesel soot particles: for example, the mean radius of gyration for soot is significantly smaller. Soot particle suspensions in n-dodecane comprise relatively loose mass fractals compared to the corresponding carbon black suspensions. SAXS also provides evidence for copolymer adsorption and indicates that addition of either copolymer transforms the initially compact agglomerates into relatively loose aggregates, while the primary particles remain unchanged. It is believed that this is also the case for diesel soot. In favourable cases, similar experimental data is obtained for carbon black and diesel soot with both copolymer dispersants. However, it is not difficult to identify certain copolymer-particle-solvent combinations for which substantial differences can be observed. Such observations are most likely the result of dissimilar surface chemistries, which can have a profound effect on the colloidal stability.

High levels of soot-in-oil can cause an increase in engine wear and oil viscosity, thus reducing oil drain intervals. The mechanisms by which soot particles are entrained into the bulk oil are not well understood. The research reported in this thesis addresses questions on the mechanisms of soot transfer to the lubricating oil in light-duty diesel engines with high pressure EGR systems. Deposition as a result of blow-by gas passing the piston ring pack and by absorption to the oil film on the cylinder liner via thermophoresis are soot transfer mechanisms that have been considered in detail. The investigations are based on analytical and simulation studies, and results based on complementary experimental studies are used to validate these. The experimental investigations aimed at evaluating the typical rate of accumulation and size distribution of soot agglomerates in oil. The oil samples analysed were collected during regular services from light-duty diesel engine vehicles. These were representative of vehicles meeting Euro IV and V emission regulation standards driven under real-world conditions. The rate of soot-in-oil was determined by thermogravimetric analysis and results showed a concentration of approximately 1 wt% of soot-in-oil after 15,000 km. The particle size distribution was determined using a novel technique, Nanoparticle Tracking Analysis (NTA), applied for the first time to soot-laden oil samples by the author [1, 2]. Results showed an average particle size distribution of 150 nm, irrespective of oil drain interval. Almost the totality of the particles were between 70 and 400 nm, with micro particles not detected in any of the samples analysed. For the samples investigated in this work, the Euro standard did not influence either the rate of soot deposition or the particles size distribution. To the author’s best knowledge, this is the first time that rate of soot deposition and particles size distribution from oil samples collected from vehicles of different Euro standard driven under real-world conditions are analysed and compared. Exhaust Gas Recirculation (EGR) is a common technique used in diesel engines in order to reduce NO¬x emissions. However, it has the drawback that it increases the production of soot. In this work, particular attention has been given to its effects on the rate of soot deposition in oil. Both its influence on the soot produced during the combustion process and on the soot re-introduced in the combustion chamber by the EGR gas has been investigated through CFD simulations using Kiva-3V. Examining the relative importance of near–surface transport of soot by thermophoresis to the oil film on the liner and from blow-by gases to surfaces in the ring pack shows the former to be the dominant mechanism of soot transfer. EGR increases the rate of deposition of soot on the liner not only by increasing net production of soot, but also through the re-cycled particles. At EGR levels higher than 20%, the contribution of the Re-cycled soot becomes the major source for soot-in-oil. The study of soot deposition was evaluated during the entire engine cycle, including compression stroke and post-Exhaust Valve Opening (EVO) period. Existing deposition models found in the literature typically limit the domain to only from the Start of Injection (SOI) to (EVO) period [3-5]. Results from this thesis indicated that compression stroke and post-EVO period can contribute up to 30% of the total rate of soot deposition into oil.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 99-101).
Engine oil lubricants play a critical role in controlling mechanical friction in internal combustion engines by reducing metal-on-metal contact. This implies the importance of understanding lubricant optimization at the piston ring-cylinder liner interface. Lubricating oil composition varies along the liner and throughout the engine. Composition changes occur due to degradation, vaporization, mixing during ring passage, fuel dilution, particulate matter contamination, and combustion gases getting onto the liner causing wear and erosion. These chemical and physical properties change oil composition and in-situ oil properties. The objective of this thesis is to discuss the development of an oil composition model to determine rheological properties at critical rubbing surfaces due to oil transport, vaporization, fuel dilution, and soot contamination. This study will specifically focus on the oil on the cylinder liner because the interaction between piston assembly and cylinder wall is where most of the mechanical friction originates. The first physical process discussed is oil mixing due to piston movement. Axial mixing analysis shows that mixing only occurs when the piston ring is above the oil particle location. Flow rates are calculated at each liner position from using piston speed, film thickness, and pressure gradient parameters. From this basic model of oil transport, chemical processes are applied to each species in each different liner location. For the process of vaporization, due to high temperatures near the top dead center of the piston, light volatile hydrocarbons vaporize and leave the system. Light carbon number species disappear at a faster rate due to their high volatility and vaporization rates. This results in retention of heavier hydrocarbon species near the top zone of the cylinder liner model. Vaporization rates for different species in each liner location are obtained by looking at individual vapor pressures, mass transfer coefficients, and other oil properties. The link between composition and viscosity is a blending equation. The Arrhenius blending equation is used to calculate mixture viscosity from the summation of different species composition and component viscosity values. A combination of composition results shows that near the top dead center or top zone, the viscosity is higher than just considering temperature effects on oil viscosity. The impact of this vaporization component shows that the addition of a non-volatile oil species near the top dead center of the cylinder liner has the ability to flatten the species viscosity versus liner location curve. Other rheology applications were studied for effects of fuel dilution, additive concentrations, and also soot contamination. This new oil composition model solves for in-situ compositional changes for different oil species due to different physical and chemical processes along the cylinder liner. This change in composition causes a change in viscosity of the overall mixture which is solved for with blending equations. Then from mixture viscosity values, friction and wear can be calculated to optimize the lubricant for fuel efficiency.
by Grace Xiang Gu.
S.M.

L'émission dans l'atmosphère de nanoparticules issues des transports préoccupe la communauté scientifique à cause de leurs impacts probables sur le changement climatique. La compréhension de l'effet de ces émissions sur l'environnement reste faible principalement à cause du manque de données expérimentales sur la caractérisation de ces nanoparticules. Ce travail est axé sur les propriétés physico-chimiques des nanoparticules de combustion et sur leur interaction avec l'eau. L'hydroscopicité est l'un des paramètres déterminants liés à la formation des noyaux de condensation des nuages (NCN). Les données expérimentales montrent des différences dans la microstructure, la composition chimique et la morphologie des suies de laboratoire et des résidus émis par les transports. Les quantités d'eau absorbées sur la suie de chambre de combustion de moteur d'avion et sur les résidus issus de la combustion de fioul lourd et de diesel sont bien plus importantes que sur les suies de laboratoire. Nous pouvons ainsi supposer que ces particules agissent comme des noyaux actifs dans la formation des NCN
Transport emission of nanoparticles into atmosphere is of major interest because of its possible effect on climate changes. The understanding of the potential environmental effect of the aviation and ship emission is still poor maintly because of the lack in the experimental characterization of these nanoparticules. The present work focuses on physico-chemical properties of combustion nanoparticles and their interaction with water. Hygroscopicity is on of the key parameters that are related to could condensation nuclei (CCN) activity and the environnemental effect. Experimental data show differences in the microstructure, elemental composition residuals coming from marine transport emitted residuals. Water uptake on combustion residuals coming from marine transport and aviation is higher than for laboratory-produced samples. We can therfore guess that these particules act as active CCN in the atmosphere

Modern engine technologies are subject to increasingly tighter emission standards and recent number-based regulations have become a new challenge, since historically only a mass-based regulation needed to be met. This evolution derives from the need to control the emissions of very fine particles, that are believed to cause more damage than larger ones. The aim of the present work is to provide further guidance in understanding the mechanisms of particle emission processes in Spark-Ignition (SI) engines. By means of both numerical and experimental investigations, it tries to answer some still open questions related to this complex topic. Different fuels are considered, such as gasoline and other promising cleaner alternatives for the future, including natural gas. 3-D Computational Fluid Dynamics simulation are used as useful additional tool to investigate the fuel-related soot emissions and help explain the experimental-derived results. The modified version of the KIVA-3V code, developed at the Engine Research Center (ERC) of the University of Wisconsin-Madison, is used for the present modeling work. It includes improvements in its ignition, combustion and emission models. In particular, a semi-detailed soot model and a chemical kinetic model, including Poly-Aromatic Hydrocarbon formation, are coupled with a SI model and the G equation flame propagation model for the engine simulations and for predictions of soot mass and particulate number density. The present work improves and extends the laminar flame speed correlations for several fuels of practical use in order to assure the correct prediction of combustion phasing and in-cylinder pressure evolution. The effects of a load increase achieved by pure oxygen addition in gasoline SI engines, as well as, the influence of natural gas composition on combustion are investigated. Furthermore, additional extensive experimental investigations provide more insights about the effects of lubricant oil on particle emissions from both gasoline and natural gas SI engines. In this last case both Port Fuel and Direct Injection mode are considered. The experimental tests were performed at the �Istituto Motori CNR�, Italy.

This paper compares 20% bio-diesel (B20-choice white grease) fuel with baseline ultra low sulfur diesel (ULSD) fuel on the emissions and performance of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) coupled to a light-duty 4-cylinder 2.8-liter common-rail DI diesel engine. The present paper focuses on the comparison of the fuel effects on loading and active regeneration of the DPF between B20 and ULSD. B20, in general, produces less soot and has lower regeneration temperature compared to soot loaded with ULSD. NO2 concentrations before the DPF were found to be 6% higher with B20, indicating more availability of NO2 to oxidize the soot. Exhaust speciation of the NO2 availability indicates that the slight increase in NOx from B20 is not the dominant cause for the lower temperature regeneration and faster regeneration rate but the reactivity of the soot that is in the DPF. Formaldehyde concentrations are found to be higher with B20 during regeneration due to increased oxygen concentrations in the exhaust stream. Finally the oil dilution effect due to post injection to actively regenerate the DPF is also investigated using a prototype oil sensor and FTIR instrumentation. Utilizing an active regeneration strategy accentuates the possibility of fuel oil dilution of the engine oil. The onboard viscosity oil sensor used was in good agreement with the viscosity bench test and FTIR analysis and provided oil viscosity measurement over the course of the project. Operation with B20 shows significant fuel dilution and needs to be monitored to prevent engine deterioration.

In recent years, legislative authorities in the US, Europe and Japan have steadily reduced engine exhaust emissions, i.e., carbon monoxide (CO), hydrocarbons (HC), sulphur, particulate matter (PM) and nitrogen oxides (NOx) to improve air quality. To meet these requirements engine manufacturers have had to make significant design changes and as a consequence new engine lubricant specifications from Industry bodies (ACEA, EMA, JAMA) and individual OEMs have had to be introduced to ensure adequate lubrication of these new engines. This has led to significant changes to heavy-duty diesel engine oil (HDDEO) oil formulation composition. Engine design modifications to increase fuel combustion efficiency such as increased peak cylinder pressure and increased fuel injection pressures have placed higher stress on piston rings and liners, bearings and valve train components [1], and improved oil consumption has meant longer oil residence time in the piston ring belt area. The practice of retarded fuel injection timing and exhaust gas recirculation (EGR) as measures to reduce NOx levels by reducing peak combustion temperature has had a considerable impact on lubricant performance. Retarded injection leads to higher soot levels which can cause valve train wear and piston ring liner wear and soot-induced thickening, whilst EGR leads to increased corrosive acids and wear in the combustion chamber. Currently in Europe, Euro 3 heavy-duty engines predominantly use retarded fuel injection as the primary NOx emission control strategy although there are cases where EGR is used. In the US, cooled EGR is used by most engine manufacturers to meet US 2002 emissions. HDDEO’s contain a combination of performance additives such as overbased metal detergents, dispersants, antiwear agents and antioxidants designed to provide wear protection, engine cleanliness, and control of soot contaminants and oxidation. Other additive components include selected viscosity index (VI) improvers and pour point depressants to provide necessary viscosity characteristics and shear stability, and also anti-foam agents for oil aeration control. To meet the increased demands from low emission engines, the chemical composition of the performance additives has been modified and levels increased. Current HDDEOs optimized to meet US and European specifications contain typically between 1.3 and 1.9%wt sulphated ash, 0.1–0.14%wt phosphorus and 0.3–1.1.wt sulphur. To meet the next generation emission standards, engines will require the use of exhaust after-treatment devices. In Europe, Euro 4 emission reductions for NOx and PM, scheduled for introduction in 2005, will require the use of either selective catalytic reduction, or the use of EGR in combination with a diesel particulate filter (DPF). To meet the US 2007 requirements, higher levels of EGR than currently used, in combination with DPFs, is envisaged by most engine builders. Exhaust after-treatment devices are already used extensively in some applications such as DPFs on city buses in Europe and the US. Further NOx restrictions are scheduled for Euro 5 in 2008 and USA in 2010. NOx absorber systems, although used in gasoline engines, are still under development for heavy-duty diesel engines and may be available for 2010. Some lubricant base oil and additive components from oil consumed in the combustion chamber are believed to adversely affect the performance of after-treatment devices. Ash material from metal detergents and zinc dithiophosphates (ZDTP) can build up in the channels within particulate filters causing blockage and potentially loss of engine power, leading to a need for frequent cleaning maintenance. The role of sulphur and phosphorus in additive components is less clear. Sulphur from fuel can either oxidize to sulphur dioxide and react through to sulphuric acid, which manifests itself as particulate, or can have a poisoning effect on the catalyst itself. However, the role of sulphur containing additives is yet to be established. Phosphorus from ZDTP antiwear components can lead to a phosphate layer being deposited on catalyst surfaces, which may impair efficiency. Concerns from OEMs regarding the possible effects of ash, sulphur and phosphorus has led to chemical limits being introduced in some new and upcoming engine oil specifications. The ACEA E6 sequence restricts sulphated ash to 1.0%wt max, phosphorus to 0.08%wt max and sulphur to 0.3%wt max, while the PC-10 category scheduled for 2007 will have maximum limits of 1.0%wt sulphated ash, 0.12%wt phosphorus and 0.4%wt sulphur. The resulting constraints on the use of conventional overbased metal detergent cleanliness additives and zinc dithiophosphate antiwear additives will necessitate alternative engine oil formulation technologies to be developed in order to maintain current performance levels. Indeed, performance requirements of engine oils are expected to become more demanding for the next generation engines where emissions are further restricted. If absorbers become a major route for NOx reduction, limits on sulphur and phosphorus are likely to be more restrictive. Oil formulations meeting ACEA E6 and PC-10 chemical limits have been assessed in several key critical lubricant specification tests, looking at valve train and piston ring/cylinder liner wear, corrosive wear in bearings, piston cleanliness and soot-induced viscosity control. It is demonstrated that it is possible to achieve MB 228.5 extended oil drain performance and API CI-4 wear, corrosion and piston cleanliness requirements for current US engines equipped with EGR [2], at a sulphated ash level of 1.0%wt, and phosphorus and sulphur levels, (0.05 and 0.17%wt, respectively), considerably lower than these chemical limits. This is achievable by the use of selected low sulphur detergents, optimized primary and secondary antioxidant systems and non-phosphorus containing, ashless supplementary antiwear additives blended in synthetic basestocks. Field trials in several city bus fleets have been conducted to assess engine oil performance and durability using one of these low sulphated ash, phosphorus and sulphur (SAPS) oil formulations and to examine lubricant effects on particulate filter performance. Engine oil durability testing was conducted in bus fleets in Germany and Switzerland. These trials, involving over 100 vehicles, cover a range of engine types, e.g., Daimler Chrysler and MAN Euro 1, 2 and 3 and different fuel types (low sulphur diesel, biodiesel, and compressed natural gas) in some MAN engines. The fleets are fitted with continuously regenerating particulate filters either from new or retrofitted. Oils were tested at standard and extended drain intervals (up to 60 000km). Used oil analysis for iron, copper, lead and aluminium with the low SAPS oil in these vehicles have shown low wear rates in all engine types and comparable with a higher 1.8% ash ACEA E4, E5 quality oil. Soot levels can vary considerably, but oil viscosity is maintained within viscosity grade, even at 8% soot loading. TBN depletion and TAN accumulation rates are low showing significant residual basicity reserve and control of acidic combustion and oxidation products. Buses in Stuttgart and Berlin have been used to investigate lubricant ash effects of engine oil on particulate filter durability. Exhaust back-pressure is routinely measured and DPF filters removed and cleaned when back pressure exceeds 100 mbar. Comparison of rate of back pressure build up as a function of vehicle distance shows reduced back pressure gradients for the low SAPS oil relative to the 1.8%wt ash oil in both engine types looked at. An average reduction in back pressure gradient of 40% was found in buses equipped with OM 906LA engines in Berlin and 25% with OM 457hLA engines at both locations. Examination of the ash content in DPFs has shown a 40% reduction in the quantity of ash with the low SAPS oil. This investigation shows that it is possible to meet current long oil drain requirements whilst meeting chemical limits for future lubricants and provide benefits in DPF durability.

The objective of this study is to develop a numerical method to predict deposition and regeneration of soot in a particulate filter. The fluid dynamic and loading characteristics are described by one-dimensional differential conservation equations for mass and momentum for both inlet and outlet channel. For the inlet channel, the varying cross sectional area due to trapped soot is taken into account. The flow through the soot layer and the filter wall is approximated by Darcy’s law. The evolution of temperature of the gaseous and solid phase (soot layer and filter wall) is dealt with by one-dimensional conservation of energy. However, a two-dimensional approach was chosen for the distribution of species during regeneration within the soot layer. Under these assumptions, deposition and regeneration, the latter as thermal and fuel-additive regeneration, was predicted very satisfactorily.

A combustion system has been optimized for the Cummins N14 diesel engine using KIVA-RIF to meet CPCB2 emission norms. It has been developed to reduce lube oil soot while meeting the legislative requirements for PM and NOx. The optimization involves closed cycle combustion simulation at three operating conditions: 110%, 75% & 50% load at rated speed. A combustion CFD code, KIVA-RIF has been calibrated to simulate the experimental results at all these points. Qualitative comparison has been done between soot on liner from simulation to lube oil soot from experiments. Parameters studied during combustion simulation involved the study of piston bowl profile, injector configuration (number of holes, spray angle, and through flow), injection timing and swirl. From combustion simulation, a deep spray angle bowl has been observed as a promising solution due to improved emissions and lube oil soot. The combustion recipe identified has a characteristic PM vs NOx curve for injection timing swing. Validation of simulation results with engine testing in terms of PM, NOx, and lube oil soot has been observed in good agreement.

Diesel Particulate Filters (DPFs) are well assessed aftertreatment devices, equipping almost every modern diesel engine on the market to comply with today’s stringent emission standards. However, an accurate estimation of soot loading, which is instrumental to ensuring optimal performance of the whole engine-after-treatment assembly is still a major challenge. In fact, several highly coupled physical-chemical phenomena occur at the same time, and a vast number of engine and exhaust dependent parameters make this task even more daunting. This challenge may be solved with models characterized by different degrees of detail (0-D to 3-D) depending on the specific application. However, the use of real-time, but accurate enough models, may be of primary importance to face with advanced control challenges, such as the integration of the DPF with the engine or other critical aftertreatment components (Selective Catalytic Reduction (SCR) or other NOx control components), or to properly develop model-based OBD sensors. This paper aims at addressing real time DPF modeling issues with special regard to key parameter settings, by using the 1D code ExhAUST (Exhaust Aftertreatment Unified Simulation Tool), developed jointly by the University of Rome Tor Vergata and West Virginia University. ExhAUST is characterized by a novel and unique full analytical treatment of the wall that allows faithful representation with high degree of detail the evolution of soot loading inside the porous matrix. Numerical results are compared with experimental data gathered at West Virginia University (WVU) engine laboratory using a Mack heavy-duty diesel engine coupled to a Johnson Matthey CCRT (DOC, Diesel Oxidation Catalyst+CDPF, Catalyzed DPF) aftertreatment system. To that aim, the engine test bench has been equipped with a DPF weighing setup to track soot load over a specifically developed engine operating procedure. Obtained results indicate that the model is accurate enough to capture soot loading and back pressure histories with regard to different steady state engine operating points, without needing any tuning procedure of the key parameters. Thus, the use of ExhAUST for application to advanced after-treatment control appears promising at this stage.

An investigation of Diesel Particulate Filter (DPF) is performed to obtain deeper insight into the soot loading process. Previous paper has been devoted to the realization of a numerical model to analyse how diesel soot is deposited on the walls of a commercial filter media and to understand the influence of different engine operating conditions on the soot layer growth. The results have been validated by means of experimental data. This paper concerns with the parametrization of particulate deposition profiles and focuses on how soot profile evolves during engine operation in a specified duty cycle, starting from pre-loaded channels. Results of 3D CFD simulations are presented, in which different engine running histories are analyzed.