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Viewing 1 to 30 of 1511
2011-04-12
Technical Paper
2011-01-0143
Daniel Sabathil, Achim Koenigstein, Peter Schaffner, Jan Fritzsche, Arndt Doehler
The future EURO 6 emission standard will limit the particle number and mass for gasoline engines. The proposed limit for particle mass is 4.5 mg/km. For particle number there is not yet a limit defined but a wide range of proposals are under discussion (6E11 - 8E12 Particles/km) The particle emissions on a homogeneous SIDI engine are mainly caused by insufficient mixture preparation. A combustion improvement could be achieved by a careful recalibration as well as a hardware optimization that mainly avoids wall impingement and substoichiometric zones in the combustion chamber. The analyses of current SIDI vehicles show significant PN emission peaks during cold start and transient operation on a NEDC cycle. To give a better understanding of cause and effect of the particle formation at steady state results so as transient load steps were performed at an engine dynamometer.
2011-04-12
Journal Article
2011-01-0636
Michael Hedge, Phillip Weber, Jess Gingrich, Terrence Alger, Imad A. Khalek
Gasoline direct injected (GDI) engines are becoming a concern with respect to particulate matter (PM) emissions. The upcoming 2014 Euro 6 regulations may require a drastic reduction in solid particle number emissions from GDI engines and the proposed California Air Resources Board (CARB) LEV III regulations for 2014 and 2017 will also require some PM reduction measures. As a result, it is necessary to characterize PM emissions from GDI engines and investigate strategies that suppress particle formation during combustion. The main focus of this work was on using exhaust gas recirculation (EGR) as a means to reduce engine-out particle emissions from a GDI engine with an overall stoichiometric fuel to air mixture. A small displacement, turbocharged GDI engine was operated at a variety of steady-state conditions with differing levels of EGR to characterize total (solid plus volatile) and solid particle emissions with respect to size, number, and soot or black carbon mass.
2011-04-12
Technical Paper
2011-01-0633
Andrea De Filippo, Claudio Ciaravino, Federico Millo, Davide Vezza, Debora Fino, Nunzio Russo, Theodoros Vlachos
Experimental work was carried out on a small displacement Euro 5 automotive diesel engine alternatively fuelled with ultra low sulphur diesel (ULSD) and with two blends (30% vol.) of ULSD and of two different fatty acid methyl esters (FAME) obtained from both rapeseed methyl ester (RME) and jatropha methyl ester (JME) in order to evaluate the effects of different fuel compositions on particle number (PN) emissions. Particulate matter (PM) emissions for each fuel were characterized in terms of number and mass size distributions by means of two stage dilutions system coupled with a scanning mobility particle sizer (SMPS). Measurements were performed at three different sampling points along the exhaust system: at engine-out, downstream of the diesel oxidation catalyst (DOC) and downstream of the diesel particulate filter (DPF). Thus, it was possible to evaluate both the effects of combustion and after-treatment efficiencies on each of the tested fuels.
2011-04-12
Journal Article
2011-01-0635
Imad A. Khalek, Thomas Bougher
A solid particle number measurement system (SPNMS) was developed using a catalytic stripper (CS) technology instead of an evaporation tube (ET). The ET is used in commercially available systems, compliant with the Particle Measurement Program (PMP) protocol developed for European Union (EU) solid particle number regulations. The catalytic stripper consists of a small core of a diesel exhaust oxidation catalyst. The SPNMS/CS met all performance requirements under the PMP protocol. It showed a much better performance in removing large volatile tetracontane particles down to a size well below the PMP lower cut-size of 23 nm, compared to a SPNMS equipped with an ET instead of a CS. The SPNMS/CS also showed a similar performance to a commercially available system when used on a gasoline direct injection (GDI) engine exhaust.
2011-04-12
Technical Paper
2011-01-0620
Di Yao, Diming Lou, Zhiyuan Hu, Piqiang Tan
An EURO 3 certified common rail diesel engine was fueled with pure petroleum diesel (EURO 4 standard) and three different alternative blended diesel fuels, 10% biodiesel blended diesel (B10), 10% gas to liquid blended diesel (G10) and 10% water emulsified diesel (E10). Tests were performed at different engine speeds and load states. Particle number concentration and size distribution data were obtained from an engine exhaust particle sizer (EEPS). Over all the working conditions, total particle and nucleation mode particle number concentration among these fuels from high to low were in this order: B10, E10, pure diesel and G10. Proportions for nucleation mode particle over all the operating states in that order were 89%, 82%, 59% and 66%. Particle size distributions of B10 and E10 presented bimodal logarithmic distributions with outstanding nucleation mode peaks at all working conditions.
2011-04-12
Technical Paper
2011-01-0632
Andrea De Filippo
This paper focuses on measuring particle emissions of a representative light-duty diesel vehicle equipped with different engine exhaust aftertreatment in close-coupled position, including one designed to meet the upcoming Euro 6 emission standards. The latter combines a lean NOx trap (LNT) and a diesel particulate filter (DPF) in series to simultaneously reduce NOx and PM. Particle Matter (PM) and particle number emissions are measured throughout testing procedure and instrumentation which are compliant with the UN-ECE Regulation 83 proposals. Specifically measuring devices for particle number emissions, provided by two different suppliers, are alternatively used. No significant differences are observed due to the different system employed. On the other hand particle size distributions are measured by means of a specific experimental set-up including a two stage dilution system and an electrical low pressure impactor (ELPI).
2011-04-12
Technical Paper
2011-01-0628
Silvana Di Iorio, Maurizio Lazzaro, Paolo Sementa, Bianca Maria Vaglieco, Francesco Catapano
The use of oxygenated and renewable fuels is nowadays a widespread means to reduce regulated pollutant emissions produced by internal combustion engines, as well as to reduce the greenhouse impact of transportation. Besides PM, NOx and HC emissions, also the size distribution of particles emitted at the engine exhaust represent meaningful information, considering its adverse effects on the environment and human health. In this work, the results of a comprehensive investigation on the combustion characteristics and the exhaust emissions of a GDI high performance engine, fuelled with pure bio-ethanol and European gasoline, are shown. The engine is a 4-cylinder, 4-stroke, 1750 cm₃ displacement, and turbocharged. The engine was operated at different speed/load conditions and two fuel injection strategies were investigated: homogeneous charge mode and stratified charge mode.
2011-04-12
Technical Paper
2011-01-0692
Hamid R. Rahai, Ehsan Shamloo, Jeremy Ralph Bonifacio
The effects of humid air on the performance of a naturally aspired three-cylinder diesel engine with low sulfur diesel fuel have been investigated. The additions of the humidity to intake air were performed with a variable steam generator using distilled water, where the relative humidity levels of the intake air were changed from the ambient conditions of 65% to 75% and 95% levels. The tests were performed at two approximate engine output brake horse powers (BHP) of 5.9, and 8.9. Results showed approximately 3.7% and 22.5% reduction in NO x emissions when the relative humidity of the air was increased from 65% (the ambient relative humidity) to 75% and 95% respectively. The addition of the humidity results in increases in the CO, CO₂, and particulate matter (PM), by approximately 3.7, 3.55, 14.9 percents at 5.9 BHP and 22, 2.8, and 9.3 percents at 8.9 BHP. There was no change in the brake specific fuel consumption (BSFC) at 5.9 BHP and about 2.7 increase in the BSFC at 8.9 BHP.
2013-04-08
Journal Article
2013-01-1305
Ian Whelan, David Timoney, William Smith, Stephen Samuel
This work investigates the effect of a three-way catalytic converter and sampling dilution ratio on nano-scale exhaust particulate matter emissions from a gasoline direct-injection engine during cold-start and warm-up transients. Experimental results are presented from a four cylinder in-line, four stroke, wall-guided direct-injection, turbo-charged and inter-cooled 1.6 litre gasoline engine. A fast-response particulate spectrometer for exhaust nano-particle measurement up to 1000 nm was utilised. It was observed that the three-way catalytic converter had a significant effect on particle number density, reducing the total particle number by up to 65 % over the duration of the cold-start test. The greatest change in particle number density occurred for particles less than 23 nm diameter, with reductions of up to 95 % being observed, whilst the number density for particles above 50 nm diameter exhibited a significant increase.
2013-11-27
Technical Paper
2013-01-2759
Pedro Manuel Barroso Guzman, Xavier Ribas, José María García Sr, Mario Pita Sr
The objective of this study is to describe the results on Particle Matter and CO2 emissions when an existing Heavy-Duty diesel engine for on-highway truck applications is converted to a Dual-fuel engine (diesel + Natural Gas) during the freeway part of transient worldwide emission tests. A Dual-fuel engine with Homogeneous Gas Charge Injection in the intake line before turbocharger was considered. The results showed the feasibility of this kind of technology for transient operation reaching a significant reduction of Particle Matter plus a decrement in CO2 emissions compared to diesel baseline engine. The results of gas energy replacement ratio, brake fuel conversion efficiency, CO and unburned hydrocarbons in the exhaust gases are also shown.
2013-09-08
Technical Paper
2013-24-0167
Stavros Amanatidis, Leonidas Ntziachristos, Zissis Samaras, Kauko Janka, Juha Tikkanen
The Pegasor Particle Sensor (PPS) has been earlier presented by Ntziachristos et al. (SAE Paper 2011-01-0626) as a novel small and robust instrument that can be directly installed in the exhaust line to measure exhaust particles without any dilution. The instrument is based on the electrical detection of aerosol. It is increasingly being used to measure exhaust particles from engines and vehicles with different exhaust configurations. In this study, a number of tests have been conducted using two sensors in parallel, one directly installed in the tailpipe and one installed in the CVS, side by side to the PM sampling filter. Aim of the study was to make recommendations on the proper use of the sensor and to check how the sensor signal compares to particulate mass, soot concentration, and particle number. A first finding is that external heating has to be provided to the sensor to avoid condensation.
2013-09-08
Technical Paper
2013-24-0168
Michal Vojtisek-Lom
Traditional smoke opacity measurement, performed on diesel engines during regular emissions inspections, sensitive primarily to larger particles of elemental carbon, is very little sensitive to nanoparticles and to semi-volatile “organic carbon” particles. For this reason, it no longer suffices as a high emitter detection tool for modern vehicles with a particle filter or for advanced low-emissions technology where semi-volatile organic particles are the dominant fraction of particulate matter. This paper investigates the potential of common low-cost ionization type smoke detectors, produced in mass quantities for fire detection in buildings, as a tool to measure particle emissions in vehicular exhaust. Two ionization chambers were used to measure both raw and diluted exhaust of various engines powered by diesel fuel and biofuels under laboratory conditions as well as on the road.
2013-09-08
Technical Paper
2013-24-0169
Richard Viskup, Thomas Stanger, Luigi del Re, Tristan Reinisch, Alexander Bergmann
The Laser Induced Incandescence technique (LII) is a sensitive optical method for reliable spatially and temporally resolved measurement of particulate matter (PM) concentration. This technique appears to be suitable for measurement of fast transient PM emissions, from diesel engines, which forms the main fraction of total emissions during standardized test cycles. However, the existing commercial LII devices require modifications in the exhaust gas flow, dilution, sampling cell, or it measure only in a partial stream. This article presents the development of a laser based optical setup - LII for rapid in-situ measurement of PM concentrations during the combustion process of a diesel production engine. The presented LII setup is suitable for direct in-situ, full stream, measurements of soot emissions without needs of dilution or a sampling cell.
2013-09-08
Technical Paper
2013-24-0175
Daniele Littera, Alessandro Cozzolini, Marc Besch, Mario Velardi, Daniel Carder, Mridul Gautam
Stringent emission regulations have forced drastic technological improvements in diesel after treatment systems, particularly in reducing Particulate Matter (PM) emissions. Those improvements generally regard the use of Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF) and lately also the use of Selective Catalyst Reduction (SCR) systems along with improved engine control strategies for reduction of NOx emissions from these engines. Studies that have led to these technological advancements were made in controlled laboratory environment and are not representative of real world emissions from these engines or vehicles. In addition, formation and evolution of PM from these engines are extremely sensitive to overall changes in the dilution process.
2013-09-08
Journal Article
2013-24-0177
Philipp Vögelin, Peter Obrecht, Konstantinos Boulouchos
Future engine emission legislation regulates soot from Diesel engines strictly and requires improvements in engine calibration, fast response sensor equipment and exhaust gas aftertreatment systems. The in-cylinder phenomena of soot formation and oxidation can be analysed using a pyrometer with optical access to the combustion chamber. The pyrometer collects the radiation of soot particles during diffusion combustion, and allows the calculation of soot temperature and a proportional value for the in-cylinder soot density (KL). A four-cylinder heavy-duty Diesel engine was equipped in all cylinders with prototype pyrometers and state of the art pressure transducers. The cylinder specific data was recorded crank angle-resolved for a set of steady-state and transient operating conditions, as well as exhaust gas recirculation (EGR) addition and over a wide range of soot emissions.
2013-09-08
Technical Paper
2013-24-0180
Thomas Stanger, Richard Viskup, Luigi del Re, Alexander Bergmann, Tristan Reinisch
Measurements of transient emissions become more important due to the increasing contribution of transient operation to the total tail pipe emissions. While for many quantities measurement devices with response time in the range of few milliseconds exist, the same is not true for particulate matter(PM). Pulsed Laser Induced Incandescence (LII) is widely used in experimental setups and may offer a viable approach also for production engines, but the specific nature of LII raises doubts on the quantitative precision achievable by the method, especially in transient operation. Indeed, there are two main problems in particular for dynamic measurements. On one side, the emitted laser power must be high enough to excite a sufficiently large number of particles within the observed area, but not as high to destroy them, and varying engine operating conditions imply changes in the number and size distribution of the particles as well.
2004-03-08
Technical Paper
2004-01-0158
Gerd Gaiser, Patrick Mucha
Published investigations on the calculation of pressure drop of diesel particulate filters consider the contribution of substrate, soot, channel flow and inertial effects at the inlet and outlet of the channels. The model presented in this work considers further contributions as the oil ash and additive ash and their effects on the DPF pressure drop. It is shown that different types of ash deposit which are caused by different driving cycles and different regeneration modes, will result in a significantly different pressure drop even at the same total amount of ash. It will be shown that in the case without soot load the ash deposit at the wall will result in a higher pressure drop than the same amount of ash being deposited at the rear end of the channels. It is also shown that at a higher soot load this behaviour will be inverted. In addition this work considers a variable permeability of the soot layer varying with the soot load of the filter.
2004-03-08
Technical Paper
2004-01-0578
Tatsuji Mizuno, Juji Suzuki
We, at Toyota, have been working to develop a new DPNR (Diesel Particulate-NOx Reduction) system to decrease both PM and NOx emissions by combining the NOx storage-reduction catalyst for direct injection gasoline engines with the most advanced engine control technologies. The purpose of the DPNR catalyst is to decrease PM and NOx in order to purify automotive exhaust gas. To reduce PM emissions, the PM trapping rate and PM oxidizing performance must be improved. Since the deposition of PM increases the pressure drop across the catalytic converter, it should also be suppressed. To attain these objectives, we have developed a new DPNR catalyst by the adoption of a new porous substrate structure and the improvement of the catalyst coating technique. The new DPNR catalyst will be mounted on the Avensis for commercial use in the European market.
2004-03-08
Technical Paper
2004-01-0577
Marco Ranalli, Stefan Schmidt, Lee Watts
Simultaneous particulate and NOx reduction represents the next step to the reduction of diesel emissions. One of the most promising concepts to achieve this target involves the combination of two technologies already in use in the after-treatment technology - Diesel Particulate Filter and NOx Storage Catalyst - in the same component. The major issue to be solved is the design of a complex thermal strategy, for the regeneration of NOx emissions, particulate matter and possibly sulfates. For this set-up to function properly the engine must periodically generate a rich spike to induce the NOx desorption process. The system must also increase the exhaust gas temperature to induce the soot oxidation process. Complicating matters further, the regeneration process of the filter must also be controlled to avoid substrate or washcoat damage.
2004-03-08
Technical Paper
2004-01-0579
Akira Shoji, Shinji Kamoshita, Tetsu Watanabe, Toshiaki Tanaka, Masahiko Yabe
We have realized ultra low exhaust emission that meets U-LEV standards in Japan by applying a simultaneous reduction system of NOx and particulate matter (hereinafter referred to as PM) to the diesel engine for light-duty trucks. This system has been introduced to the Japanese market since September 2003. The basic technologies comprise Diesel Particulate-NOx Reduction system (DPNR), common rail injection system necessary for accurately controlling the catalyst bed temperature and the air to fuel ratio, electrically controlled EGR system, high-efficiency EGR cooler, and the fuel injector installed on the upper stream of catalyst that feeds over-rich fuel-air mixture for NOx reduction with DPNR catalyst and SOx discharging. To realize simultaneous reduction of NOx and PM with DPNR, the important issues include the clogging of PM to the filters after continuous driving at low vehicle speed and the sulfur poisoning of the catalyst.
2004-03-08
Technical Paper
2004-01-1439
Leonidas Ntziachristos, Barouch Giechaskiel, Panayotis Pistikopoulos, Zissis Samaras, Urs Mathis, Martin Mohr, Jyrki Ristimäki, Jorma Keskinen, Pirita Mikkanen, Roberto Casati, Volker Scheer, Rainer Vogt
This paper presents a novel partial flow sampling system for the characterization of airborne exhaust particle emissions. The sampled aerosol is first conditioned in a porous dilutor and then subsequent ejector dilutors are used to decrease its concentration to the range of the instrumentation used. First we examine the sensitivity of aerosol properties to boundary sampling conditions. This information is then used to select suitable sampling parameters to distinguish both the nucleation and the accumulation mode. Selecting appropriate sampling parameters, it is demonstrated that a distinct nucleation mode can be formed and measured with different instruments. Using these parameters we examine the performance of the system over transient vehicle operation. Additionally, we performed calculations of particle losses in the various components of the system which are then used to correct signals from the instruments.
2004-03-08
Technical Paper
2004-01-1444
Barbara Zelenka, Günter Hohenberg, Wolfgang Thiel, Peter M. Ziegler
This paper reports on the development and testing of a compact and mobile CVS system for the measurement of particulate matter emissions of diesel passenger cars. It consists of the same components as a conventional CVS system but needs much less space. Reducing the size of the CVS system was achieved by the optimization of the turbulent flow in the dilution tunnel by the use of an optimized mixing chamber, in which the engine exhaust gas is diluted with filtered ambient air. The measures taken to improve the turbulence in the dilution tunnel lead to the same effect as a tunnel with dimensions according to the legislative regulations. All the components of the mobile CVS system are arranged in a very compact design, so that the new system has a size of only about (1.70 x 0.80 x 2.10) m. Due to the mobility which is possible with such a design, the new system can be quickly adapted to different engine and vehicle test cells for passenger cars.
2004-03-08
Technical Paper
2004-01-1424
J. Oesterle, G. Gaiser, P. Zacke
Based on the results achieved with the progressive spin element in previous work [1], the focus in this paper is on the loading and regeneration behaviour with a spin element during different engine operating conditions and driving cycles. The temperature distribution inside the diesel particulate filter, the ash and soot loading and regeneration behaviour during different driving cycles have been examined. It can be shown that the use of a progressive spin element leads to superior performance of the DPF through better usage of the available filter volume and minimises the disadvantages e.g. for catalytic coated filters concerning aging. Through careful design of the available parameters of the progressive spin element the additional backpressure due to the spin element can be reduced without loosing the positive influence onto the flow distribution.
2004-03-08
Technical Paper
2004-01-1384
Kimiko Imai, Hiroyuki Kato, Tomohide Nishino, Kazuhiro Fukumoto
One of typical outcome of the desire for increasing passenger comfort is that especially for deodorant efficiency. Since customers are becoming so sensitive about cabin odor, development of more effective deodorant filter is strongly required. Out side of vehicle, which most being disliked is diesel odor, therefore, analysis on this diesel gas and investigation to identity the ingredient for the main cause of the strong odor were executed, and found that acetaldehyde gas is the one. Therefore, identification of the chemical that adsorb acetaldehyde gas with being impregnated in activated carbon was required, since activated carbon itself does not have ability of adsorbing acetaldehyde gas, and finally found appropriate chemical, vitamin Bx. At the end of this report, sensory evaluation result by twenty panelists with deodorant type cabin air filter impregnated with vitamin Bx, and its efficiency for deodorant will be shown at the end of this report.
2004-06-08
Technical Paper
2004-01-1939
Paul Richards, B. Terry, J. Chadderton, M. W. Vincent
In an attempt to improve ambient air quality, retrofit programmes have been encouraged; targeting reductions in PM emissions by means of diesel particulate filters (DPFs). However depending on the DPF design and operating conditions increased nitrogen dioxide (NO2) emissions have been observed, which is causing concern. Previous work showed that retrofitting a DPF system employing a fuel borne catalyst (FBC) to facilitate regeneration, reduced NO2 emissions. This paper outlines the investigation of a base metal coated DPF to enhance the reduction of NO2. Such a DPF system has been fitted to older technology buses and has demonstrated reliable field performance.
2004-06-08
Technical Paper
2004-01-1937
Jean-Claude Fayard, Thierry Seguelong
Diesel urban buses as well as garbage trucks are part of the particulate emissions sources that affect the city air quality. Retrofit programs have developed Diesel particulate filters approaches in order to limit the particulate emissions in the cities. To fit the particular duty driving cycle requirements, a new active Diesel particulate filter (DPF) system is proposed to control the filters regeneration. The DPF system consists of: several particulate filter units; an oxidation catalyst placed in front of the filters; valves and jacks actuators allowing thermal insulation of the filters; control valves actuators; temperature and pressure sensors; and an electronic control unit and monitoring of the DPF system. Furthermore, in order to fully control the filters regeneration, an additional heat injection strategy, based on Diesel fuel injection over the oxidation catalyst, heats up the filters individually, according to the position of the insulation valves.
2004-06-08
Technical Paper
2004-01-1942
Ken Nagashima, Yasuyuki Banno, Yasuharu Kanno, Makoto Nagata
Combustion behavior of the SOF (Soluble organic fraction) fraction of diesel particulate by flow-thru type diesel oxidation catalysts (DOC) was studied. A two brick DOC system with an air gap showed higher SOF performance than a single brick DOC of the same total volume. Collision frequency of the TPM (total particulate matter) to the catalyst layer was studied by calculation of the turbulence energy in the gas flow channel. No large difference in collision frequency was observed between one brick and two bricks. The front face effect was calculated from the geometric surface and it was confirmed that such an effect was small in the two brick DOC case. The SOF performance advantage for the two brick DOC system separated by an air gap was due to a thermo-mass effect created by reducing the DOC volume.
2004-06-08
Technical Paper
2004-01-1962
Liisa Pirjola, Heikki Parviainen, Maija Lappi, Kaarle Hämeri, Tareq Hussein
A mobile laboratory was designed and built in Helsinki Polytechnic, in close co-operation with the University of Helsinki, to measure traffic pollutants with high temporal and spatial resolution under real world conditions. The laboratory provides measurements of gaseous pollutants and particle size number distributions as well as meteorological and geographical parameters. Two inlet systems are employed to enable the “chasing” of different type of vehicles. This paper introduces the construction and technical details of the mobile laboratory, and presents the results from “chasing” experiments performed in the Helsinki metropolitan area during a field campaign in June, 2003. New particle formation was found while driving in the exhaust plume of vehicles. Approximately 75% of the total particle number concentration was due to particles smaller than 50 nm in size.
2004-06-08
Technical Paper
2004-01-1966
Daisuke Kawano, Hiroyoshi Naito, Hisakazu Suzuki, Hajime Ishii, Shigeo Hori, Yuichi Goto, Matsuo Odaka
Homogeneous Charge Compression Ignition (HCCI) is effective for the simultaneous reduction of soot and NOx emissions from diesel engine. In general, high octane number and volatility fuels (gasoline components or gaseous fuels) are used for HCCI operation, because very lean mixture must be formed during ignition delay of the fuel. However, it is necessary to improve fuel injection systems, when these fuels are used in diesel engine. The purpose of the present study is the achievement of HCCI combustion in DI diesel engine without the large-scale improvements of engine components. Various high octane number fuels are mixed with diesel fuel as a base fuel, and the mixed fuels are directly applied to DI diesel engine. At first, the cylinder pressure and heat release rate of each mixed fuel are analyzed. The ignition delay of HCCI operation decreases with an increase in the operation load, although that of conventional diesel operation does not almost varied.
2004-06-08
Technical Paper
2004-01-1945
Thierry Colliou, Jacques Lavy, Brigitte Martin, Karine Chandès, Guy Pichon, Loys Pierron
To ensure overall optimisation of heavy duty engine performance (with the respect of NOx&PM future European and US emissions standards), the use of a high efficiency NOx after-treatment system such as a NOx trap appears to be necessary. But running in rich conditions, even for a short time, leads to a large increase of particulate emissions so that a particulate filter is required. A first investigation with a NOx-trap only has been carried out to evaluate and optimise the storage, destorage and reduction phases from the NOx conversion efficiency and fuel penalty trade-off. The equivalence ratio level, the fuel penalty and the temperature level of the NOx-trap have been shown as a key parameter. Respective DPF and LNA locations have been studied. The configuration with the NOx-trap upstream provides the best NOx / fuel penalty trade-off since it allows NOx slip reduction and does not disturb the rich pulses.
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