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Viewing 1 to 30 of 1781
2011-04-12
Technical Paper
2011-01-0676
Fuming Xiao, Ghazi A. Karim
The dual-fuel engine represents in principle a simple flexible approach to employing gaseous fuels in conventional diesel engines. Compared to the use of hydrogen in spark ignition engines, there is relatively limited information about its effect when present as a supplementary fuel in suitably modified conventional compression ignition engines. This is especially for engines of the IDI type and when employing only low concentrations of hydrogen in the intake air while retaining the injection of large diesel fuel quantities. In the present contribution, a 3D-CFD model based on KIVA 3, developed with a “reduced” detailed chemical kinetics of 294 elementary reaction steps with 79 chemical species for diesel fuel combustion which includes 20 steps for the oxidation of hydrogen, is outlined.
2011-04-12
Journal Article
2011-01-0694
Yue-Yun Wang, Yongsheng He, Sai Rajagopalan
Fuel economy improvement and stringent emission regulations worldwide require advanced air charging and combustion technologies, such as low temperature combustion, PCCI or HCCI combustion. Furthermore, NOx aftertreatment systems, like Selective Catalyst Reduction (SCR) or lean NOx trap (LNT), are needed to reduce vehicle tailpipe emissions. The information on engine-out NOx emissions is essential for engine combustion optimization, for engine and aftertreatment system development, especially for those involving combustion optimization, system integration, control strategies, and for on-board diagnosis (OBD). A physical NOx sensor involves additional cost and requires on-board diagnostic algorithms to monitor the performance of the NOx sensor.
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.
2013-09-24
Technical Paper
2013-01-2424
Jyotirmoy Barman
Exhaust gas recirculation is one important measure to achieve the Bharat Stage IV, Bharat Stage V as well as the Euro V emissions legislation. EGR is one of the most promising solutions to reduce NOx to achieve Bharat Stage IV emission norms for any high specific power engine. An emissions and performance study was conducted to explore the effects of EGR and multiple injections on particulate, NOx, and BSFC. Recent work has shown that multiple injections are effective at reducing particulate. Thus, it was of interest to examine the possibility of simultaneously reducing particulate and NOx with the combined use of EGR and multiple injections. The tests were conducted on a four cylinder four valve light duty truck engine. Tests were done at emission modes (A, B & C Modes) with EGR are variation along with different injection strategies. The fuel system used was an electronically controlled, common rail injector and supporting hardware.
2013-09-08
Technical Paper
2013-24-0162
Nagaraj S. Nayak
The Selective Catalytic Reduction (SCR) based on Urea-Water-Solution (UWS) injection is an effective technique to reduce the nitrogen oxides (NOx) emitted from the exhaust gases of diesel engines. The evaporation characteristics obtained for single Urea-Water-Solution (UWS) droplet using CFD code AVL FIRE is compared with experimental values. 3D numerical model of the injection of UWS and its interaction with the exhaust gas flow and exhaust tubing is developed. The model accounts for all relevant processes appearing from the injection point to the entrance of the SCR catalyst, especially during evaporation and thermolysis of droplets, hydrolysis of isocyanic acid in gas phase, heat transfer between wall and droplets and spray/wall-interaction. The spray wall deposition is found to be varying with temperature and residence time.
2013-09-08
Journal Article
2013-24-0161
Teuvo Maunula
Stricter emission limitations for NOx and particulates in mobile diesel applications will require the combinations of active aftertreatment methods like Diesel Particulate Filters (DPF), Selective Catalytic Reduction (SCR) with urea and Lean NOx Trap (LNT) in the 2010's. A new concept is the combination of LNT+SCR, which enables on-board synthesis of ammonia (LNT), which is then removed on the SCR catalyst. The main application for this kind system will be light-duty vehicles, where LNTs are already used and the low temperature deNOx is a main target. That combinatory system was investigated by developing and selecting PtRh/LNT and SCR catalysts for that particulate application, where the maximum temperature may reach 800°C and SCR should proceed without NO2 assistance. Pt-rich, PtRh/LNT with reasonable high loadings above 80g/cft resulted in a high NOx efficiency in the experimental laboratory conditions which created also on LNTs a higher NH3 concentration for the SCR unit.
2013-09-08
Technical Paper
2013-24-0138
Ivan Arsie, Andrea Cricchio, Matteo De Cesare, Cesare Pianese, Marco Sorrentino
The paper describes suited methodologies for developing Recurrent Neural Networks (RNN) aimed at estimating NOx emissions at the exhaust of automotive Diesel engines. The proposed methodologies particularly aim at meeting the conflicting needs of feasible on-board implementation of advanced virtual sensors, such as neural network, and satisfactory prediction accuracy. Suited identification procedures and experimental tests were developed to improve RNN precision and generalization in predicting engine NOx emissions during transient operation. NOx measurements were accomplished by a fast response analyzer on a production automotive Diesel engine at the test bench. Proper post-processing of available experiments was performed to provide the identification procedure with the most exhaustive information content. The comparison between experimental results and predicted NOx values on several engine transients, exhibits high level of accuracy.
2013-09-24
Technical Paper
2013-01-2385
N. Santosh Datta
With evolution of emission norms in diesel engines, NOx emission limits became more stringent and can be met only with specific NOx emission control systems. The NOx control systems in heavy duty diesel engines are monitored for OBD regulations in on-highway applications. Additionally driver warning and inducement requirements for NOx emission control systems are to be complied in both on-highway and off-highway applications. The driver inducement requirements are defined with intent to enforce and ensure correct operation of NOx control system. The NOx control systems and inducement measures are implemented in engine Electronic Control Unit (ECU) software to be compliant to legislation. The paper focuses on driver inducement requirements for NOx emission control systems. The paper summarizes the inducement requirements with a system overview and software design to meet driver inducement requirements for EUVI legislation and CARB/EPA compliance.
2004-03-08
Technical Paper
2004-01-0120
Hitoshi Yokomura, Susumu Kouketsu, Seijiro Kotooka, Yoshiyuki Akao
EGR system is one of the most useful way to reduce NOx. In order for heavy duty diesel engines to meet more stringent exhaust emission regulations, higher EGR rate should be needed. When higher EGR rate is applied to a turbocharged and intercooled diesel engine, however, spike smoke at rapid acceleration is generated due to delay of boost pressure rise. It is needed to develop new control method of EGR to eliminate smoke spike. Therefore, the closed loop EGR control system was developed and tested. The closed loop control system controls EGR valve as feed-backing estimated air excess ratio(Lambda) by detected air mass flow and engine operation condition. The closed loop control system applied to a diesel engine with displacement of 13L and experimentally evaluated the effects of the control system at the transient test.
2004-03-08
Technical Paper
2004-01-0121
Gary D. Neely, Shizuo Sasaki, Jeffrey A. Leet
The combination of premixed charge compression ignition (PCCI) and conventional DI diesel combustion was studied on a light-duty diesel engine equipped with EGR and a common rail fuel injection system. This combustion mode is referred to as PCCI-DI combustion. The main objectives of the study were to examine the emissions, performance and combustion characteristics of the engine operating under various levels of PCCI-DI combustion to determine if this mode of combustion was a viable in-cylinder NOX emissions reduction strategy. The premixed charge was obtained with early pilot injections (up to three) using a custom engine controller. The engine test conditions were limited to light and medium loads and moderate engine speeds. Engine tests consisted of sweeps of pilot injection timing and quantity, and number of pilot injections.
2004-03-08
Technical Paper
2004-01-0125
Daisuke Shimo, Motoshi Kataoka, Hidefumi Fujimoto
A new nitrogen oxide (NOx) reduction concept is suggested. A strong vertical vortex generated within the combustion bowl can mix hot burned gas into the cold excess air at the center of the combustion-bowl. This makes the burned gas cool rapidly. Therefore, it is possible to reduce NOx, which would be produced if the burned gas remained hot. In this paper the effect was verified with a 3D-CFD analysis of spray, air, combustion gas, and thermal efficiency as well as experiments on a 4-cylinder 2.0-liter direct injection diesel engine. The results confirmed that the vertical vortex was able to be strengthened with the change of spray characteristics and the combustion bowl shapes. This strengthened vertical vortex was able to reduce NOx by approximately 20% without making smoke and thermal-efficiency worse. Above results proved the effectiveness of this method.
2004-03-08
Technical Paper
2004-01-0138
Cécile Favre, Saϊd Zidat
Euro IV emissions limits have become a major milestone for the car industry in Europe. To comply with reduced emissions targets, a significant effort was required to minimize light-off time and to improve steady state performance for the pollutants HC and NOx. The main challenges and the technical solutions are discussed in this present work. Among them are substantial catalyst improvements needed to accommodate the progressively more severe agings related to high-speed driving conditions in Europe, and the close-coupled location of the catalyst, with the introduction of the converter welded directly to the exhaust manifold. Vehicles equipped with Euro IV emissions systems have been running in the field for more than 2 years and have shown that only a systems approach, including optimized exhaust manifold and canning designs, robust engine calibration strategies and specifically developed washcoats, can lead to a cost effective emissions solution.
2004-03-08
Technical Paper
2004-01-0153
C. M. Schär, C. H. Onder, H. P. Geering, M. Elsener
Basic knowledge about the reaction kinetics of the selective catalytic reduction (SCR) as well as measurement data from a dynamometer are used for the design of a physical mean-value model of an SCR catalytic converter system. The converter system consists of an injection device for urea solution and a coated metallic honeycomb-type converter. It is mounted in the tailpipe of a mobile, heavy-duty diesel engine. The core of the catalytic converter model is a series of identical SCR cells describing the thermal and chemical behavior of the SCR catalytic converter. It may be used to design dynamic, model-based feedforward controllers for the injection of reducing agent. Measurements on the dynamometer show that these controllers significantly improve the performance of the SCR system.
2004-03-08
Technical Paper
2004-01-0155
Andrew P.E. York, Timothy C. Watling, Julian P. Cox, Isabel Z. Jones, Andrew P. Walker, Philip G. Blakeman, Thomas Ilkenhans, Ronny Allansson, Mats Lavenius
A 1-D numerical model describing the ammonia selective catalytic reduction (SCR) de-NOx process has been developed based on data measured on a laboratory microreactor for a vanadia-titania washcoated catalyst system. Kinetics for various NH3-NOx reactions were investigated, as well as those for ammonia, CO and hydrocarbon oxidation. The model has been successfully validated against engine bench measurements, over light-off and ESC tests, under a wide range of conditions, e.g. flow rate, temperature, NO2/NO ratio, and ammonia injection rate. A very good agreement between the experimental data and the model has been achieved. The model has now been used to predict the effect of NO2/NO ratio on NOx conversion, and the effect of different ammonia injection rates on the efficiency of the SCR process.
2004-03-08
Technical Paper
2004-01-0154
Rinie van Helden, Ruud Verbeek, Frank Willems, Reinier van der Welle
In the past decade, SCR deNOx technology with urea injection has grown to maturity. European OEMs will apply SCR deNOx to meet future heavy-duty emissions legislation starting with EURO-4 (2005/2006). Numerous research programs in Europe and the US have shown a variety of system layouts and control strategies. The main differences are formed by: the engine-out NOx calibration the application of an NO to NO2 catalyst open-loop or closed-loop urea dosage control. This paper gives an overview of possible SCR system configurations that are required for different stages of future emission legislation. Engine-out NOx emission is strongly influenced by ambient conditions. Projections in this study show that a combination of cold climate and a wintergrade fuel is the most severe: it may lead to 30% lower engine-out NOx emission with respect to laboratory conditions.
2004-03-08
Technical Paper
2004-01-0156
Yisun Cheng, John V. Cavataio, William D. Belanger, John W. Hoard, Robert H. Hammerle
Promising lean NOx trap (LNT) results on lean-burn gasoline engines have encouraged the development of LNTs for diesel applications. Although the fundamentals of LNT are common for both gasoline and diesel applications, there are major differences due to the character of engine operation and control strategies. The sulfur tolerance and thermal durability of current state-of-the-art diesel LNTs under the conditions that represent the thermal and chemical conditions in diesel exhaust were investigated in a laboratory flow reactor. Sulfur poisoning and thermal aging are unavoidable factors contributing to diesel LNT deactivation. The results show that sensitivity to sulfur poisoning varies with the catalyst formulations, and in some formulations the sulfur poisoning appears reversible. However, the thermal deactivation is permanent regardless of its cause, i.e., LNT de-sulfation (deSOx) or diesel particular filter (DPF) regeneration.
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
2004-01-0546
Jianwen Yi, Zhiyu Han, Zheng Xu, Lloyd E. Stanley
In the effort to improve combustion of a Light-load Stratified-Charge Direct-Injection (LSCDI) combustion system, CFD modeling, together with optical engine diagnostics and single cylinder engine testing, was applied to resolve some key technical issues. The issues associated with stratified-charge (SC) operation are combustion stability, smoke emission, and NOx emission. The challenges at homogeneous-charge operation include fuel-air mixing homogeneity at partial load operation, smoke emission and mixing homogeneity at low speed WOT, and engine knock tendency reduction at medium speed WOT operations. In SC operation, the fuel consumption is constrained with the acceptable smoke emission level and stability limit. With the optimization of piston design and injector specification, the smoke emission can be reduced. Concurrently, the combustion stability window and fuel consumption can be also significantly improved.
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
2004-01-1425
Holger Herrmuth, Thomas Cartus, Robert Ducellari, Otfried Derschmidt
While particulate filters are already being used in increasing numbers with production HSDI (High Speed Direct Injection) Diesel powertrains, combined NOx and PM reducing devices are still in the development phase. In the past, various lean NOx trap (LNT) applications using internal and external measures to enable enrichment of stoichiometric exhaust gas have been investigated. Some initial results on the integration of LNT and catalytic Diesel Particulate Filter (cDPF) functionality into HSDI powertrains have already been published, and systems consisting of a cDPF and LNT on separate bricks, as well as one brick solutions have been described without being directly compared. In the present paper a system comparison of various exhaust gas aftertreatment system architectures in combination with a prototype engine designed to fulfil future emissions legislation at lowest CO2 levels performed at AVL is described.
2004-03-08
Technical Paper
2004-01-1465
Ingemar Andersson
Combustion temperature models for spark ignited engines are investigated in this work. The temperature models are evaluated as sub-models of a model for the thermal part of ionization current. Three different combustion temperature models were investigated; a single-zone model, a mixed two-zone model and an unmixed two-zone called a kernel-zone model. The combustion temperature is derived from cylinder pressure. The ionization current model structure also contain sub-models for formation of nitric oxide (NO) and its thermal ionization. The model output is compared to the measured ionization currents with respect to peak amplitude and position. Also, two models for NO formation are evaluated. The first is a fixed NO molar fraction model and the second is a reaction rate controlled NO formation model based on the extended Zeldovich reaction scheme.
2004-03-08
Technical Paper
2004-01-1494
Naoko Iwata, Yoshinao Suzuki, Hitoshi Kato, Masahiko Takeuchi, Aiko Sugiura
By using analytical techniques (FT-IR, TG-MS, ICP) and DFT calculations, the potassium (K) used as a storage component in NOx Catalysts can be analyzed. The results from this study show that the, K exists as K2CO3, and that the amount, molecular structure, and thermal stability of K2CO3 are different, depending on the support material (ZrO2, Al2O3, or TiO2). If the amount of K that interacts with the support to form an inactive complex oxide is decreased, the amount of K2CO3 and NOx storage is increased. The amount of the inactive K varies with the basicity of the supports. K2CO3 that exists in unstable structures on the supports can be easy to react with NOx to form the nitrate. So, the higher the quantity of unstable K2CO3, the higher the NOx storage capacity. Based on these results, a development guideline was proposed to improve the NOx storage performance.
2004-03-08
Technical Paper
2004-01-1493
Joseph R. Theis, Justin A. Ura, George W. Graham, Hung-Wen Jen, John J. Li, William L. Waktins, Christian T. Goralski
Abstract This paper summarizes results from a study on the effects of aging temperature and A/F ratio on the NOx storage capacity of a lean NOx trap. When aged at stoichiometry at 700°C, the NOx storage capacity of the NOx trap dropped considerably during the first 200 hours of aging and then at a much slower rate beyond 200 hours. The NOx storage capacity dropped more rapidly as the aging temperature increased, with the drop in capacity particularly evident between 900°C and 1000°C. The drop in NOx capacity was significantly larger for samples aged with part-time lean operation and/or part-time rich operation than for samples aged continuously at stoichiometry. The detrimental effects of lean and rich operation increased as the temperature increased. A Pt/Al2O3 model catalyst was exposed to reducing conditions at temperatures ranging from 670°C to 1041°C and then to oxidizing conditions over the same temperature range, and in-situ XRD was used to investigate Pt particle coarsening.
2004-03-08
Technical Paper
2004-01-1496
Shinji Kojima, Tomohiko Jimbo, Kenji Katoh, Shigeki Miyashita, Masao Watanabe
Our two types of NOx storage-reduction (NSR) catalyst have been tested under various conditions of thermal endurance; the performance of these catalysts have been regressed to give the formulas that enable to estimate the performance after thermal endurance; and we have found the method to simplify (shorten the duration of) the thermal endurance tests and that the thermal deterioration of NSR catalysts is controlled by the worst condition of endurance (at least approximately). The regression formula for the amount of potassium that contributes to the catalyst performance (active K) after the endurance has also been obtained. These formulas predict that the amount of active K is the least for the worst condition of endurance and suggest a difference in deterioration mechanism that reflects the performance between low and high temperatures and the portion of worse deterioration (front or rear).
2004-03-08
Technical Paper
2004-01-1495
Hidehiro Iizuka, Masato Kaneeda, Kazutoshi Higashiyama, Osamu Kuroda, Norihiro Shinotsuka, Hiroko Watanabe, Hiroshi Ohno, Toshikatsu Takanohashi, Naohiro Satoh
When the alkali metal-supported catalyst was treated at 830°C, the NOx conversion decreased because the alkali metals in the catalyst layer gradually moved to the cordierite honeycomb layer and reacted with the cordierite elements. This phenomena decreased to be added the basic metal oxide (α) in the catalyst layer. The improved catalyst with α 2 showed higher performance than the conventional catalyst in the model gas test. Moreover, the emission values of NOx, HC, and CO were 50% or less than Japanese domestic regulation values even after 830°C×60h heat treatment in a vehicle test.
2004-03-08
Technical Paper
2004-01-1402
Jean-Paul Hardy, Hamid Lahjaily, Magali Besson, Patrick Gastaldi
Thanks to a high specific torque, associated to a low fuel consumption, the market share of the Diesel engine has not stopped increasing during the last decade. Nevertheless, due to the strong emissions regulations to come, the challenge of the Diesel will be to save its advantage in CO2 and to drastically reduce NOx and particulate emissions, whilst offering the save driving pleasure. Hence new concepts of combustion are in development in order to keep NOx emissions as low as possible at an acceptable cost. The homogeneous combustion, by generating a lower pollutant level directly in the combustion chamber, seems to be a very promising way in this direction. Especially, the NADI™ concept, developed by IFP has already shown a high potential in NOx and particulate simultaneous reduction, but up to now its relative low specific power at full load compared to the next generation of conventional Diesel engines could be a major drawback for a global application.
2004-03-08
Technical Paper
2004-01-1401
Mark P. B. Musculus
It is generally accepted that exhaust NOX emissions of diesel engines increase with the degree of premixed burning. Although several mechanisms proposed in the literature are likely responsible for some aspects of the correlation, taken together, they cannot explain all observations of this correlation. In this study, thermodynamic analyses and optical/imaging diagnostics were employed in an optically-accessible, heavy-duty DI diesel engine to examine the in-cylinder mechanisms by which fuel/air premixing affects engine-out NOX emissions. Exhaust NO and NOX emissions were measured and correlated with observations of soot luminosity and jet penetration as the intake-temperature and injection timing were varied. The engine was operated at low-load conditions, for which the premixed burn was a significant fraction of the total heat released.
2004-06-08
Technical Paper
2004-01-1938
Gordon Bartley, Magdi Khair
This study was performed by the Department of Engine and Emissions Research under an SwRI® Internal Research and Development Program. The objective of the study was to evaluate the effectiveness of a system design that was an advancement over SwRI's patented Protection of Aftertreatment Systems from Sulfur (PASS™) technology.[1, 2] A Lean NOx Trap (LNT) was employed as the sulfur-sensitive emissions reduction device. Lean Sulfur Traps (LST) and Rich Sulfur Traps (RST) were formulated to provide the sulfur protection. Testing was performed to evaluate the efficiency of the LNT, the sulfur poisoning of the LNT, the efficiency of the LST, and the regeneration and protection characteristics of the PASS-2™ system. The program successfully demonstrated that an LST upstream of an LNT does provide protection for the LNT from the adverse effects of fuel-borne sulfur.
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.
Viewing 1 to 30 of 1781

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