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Viewing 151 to 180 of 23237
2016-04-05
Journal Article
2016-01-0760
Mark Sellnau, Matthew Foster, Wayne Moore, James Sinnamon, Kevin Hoyer, William Klemm
Abstract The second generation 1.8L Gasoline Direct Injection Compression Ignition (GDCI) engine was built and tested using RON91 gasoline. The engine is intended to meet stringent US Tier 3 emissions standards with diesel-like fuel efficiency. The engine utilizes a fulltime, partially premixed combustion process without combustion mode switching. The second generation engine features a pentroof combustion chamber, 400 bar central-mounted injector, 15:1 compression ratio, and low swirl and squish. Improvements were made to all engine subsystems including fuel injection, valve train, thermal management, piston and ring pack, lubrication, EGR, boost, and aftertreatment. Low firing friction was a major engine design objective. Preliminary test results indicated good improvement in brake specific fuel consumption (BSFC) over the first generation GDCI engines, while meeting targets for engine out emissions, combustion noise and stability.
2016-04-05
Journal Article
2016-01-1278
Shubhangi S. Nigade
Abstract This paper’s analysis approach combines the orthogonal array design of experiments with grey relational analysis for optimization CI engine performance using blend of Madhuca Indica biodiesel as a fuel. Grey relational theory is adopted to determine the best input parameters that give lower emission and higher performance of CI engine. Five design parameters namely; compression ratio, injection pressure, injection nozzle geometry (no. of holes on nozzle of injector), additive (AA-93 TM) and fuel fraction were selected, and four levels for each factor. To reduce an experimental effort the experiments have been performed by employing Taguchi's L16 orthogonal array for various engine performance and emission related responses. Injection nozzle geometry was found to most influencing factors. The optimal combination so obtained was further confirmed through experimentation was suitable for optimizing the performance and emission parameters of diesel engine.
2016-04-05
Journal Article
2016-01-0781
Usman Asad, Ming Zheng, Jimi Tjong
Abstract In this work, empirical investigations of the diesel-ethanol Premixed Pilot-Assisted Combustion (PPAC) are carried out on a high compression ratio (18.2:1) single-cylinder diesel engine. The tests focus on determining the minimum ethanol fraction for ultra-low NOx & soot emissions, effect of single-pilot vs. twin-pilot strategies on emissions and ignition controllability, reducing the EGR requirements, enabling clean combustion across the load range and achieving high efficiency full-load operation. The results show that both low NOx and almost zero soot emissions can be achieved but at the expense of higher unburned hydrocarbons. Compared to a single-pilot injection, a twin-pilot strategy reduces the soot emissions significantly and also lowers the NOx emissions, thereby reducing the requirements for EGR. The near-TDC pilot provides excellent control over the combustion phasing, further reducing the need of a higher EGR quantity for phasing control.
2016-04-05
Journal Article
2016-01-0791
Midhat Talibi, Paul Hellier, Ramanarayanan Balachandran, Nicos Ladommatos
Abstract Development of new fuels and engine combustion strategies for future ultra-low emission engines requires a greater level of insight into the process of emissions formation than is afforded by the approach of engine exhaust measurement. The paper describes the development of an in-cylinder gas sampling system consisting of a fast-acting, percussion-based, poppet-type sampling valve, and a heated dilution tunnel; and the deployment of the system in a single cylinder engine. A control system was also developed for the sampling valve to allow gas samples to be extracted from the engine cylinder during combustion, at any desired crank angle in the engine cycle, while the valve motion was continuously monitored using a proximity sensor. The gas sampling system was utilised on a direct injection diesel engine co-combusting a range of hydrogen-diesel fuel and methane-diesel fuel mixtures.
2016-04-05
Journal Article
2016-01-0827
J. Felipe Rodriguez, Wai K. Cheng
Abstract This work examines the effect of valve timing during cold crank-start and cold fast-idle (1200 rpm, 2 bar NIMEP) on the emissions of hydrocarbons (HC) and particulate mass and number (PM/PN). Four different cam-phaser configurations are studied in detail: 1. Baseline stock valve timing. 2. Late intake opening/closing. 3. Early exhaust opening/closing. 4. Late intake phasing combined with early exhaust phasing. Delaying the intake valve opening improves the mixture formation process and results in more than 25% reduction of the HC and of the PM/PN emissions during cold crank-start. Early exhaust valve phasing results in a deterioration of the HC and PM/PN emissions performance during cold crank-start. Nevertheless, early exhaust valve phasing slightly improves the HC emissions and substantially reduces the particulate emissions at cold fast-idle.
2016-04-05
Technical Paper
2016-01-0924
Shun Nakagawa, Ichiro Tsumagari, Shinya Sato, Koichi Machida
Abstract The conventional NOx after-treatment system could not perform sufficient NOx removal since exhaust gas temperature falls down by low-fuel-consumption and waste heat recovery of a diesel engine. In order to realize a new after-treatment system with high NOx conversion rate at a low catalyst temperature, studies on adopting an ozone generator (NO oxidization promotion) and a urea reformer (ammonia addition) into the Urea SCR (Selective Catalytic Reduction) system have been conducted.
2016-04-05
Journal Article
2016-01-0921
Ashok Kumar, Kristopher Ingram, Deepesh Goyal, Krishna Kamasamudram
Abstract Exposure of hydrocarbons (HCs) and particulate matter (PM) under certain real-world operating conditions leads to carbonaceous deposit formation on V-SCR catalysts and causes reversible degradation of its NOx conversion. In addition, uncontrolled oxidation of such carbonaceous deposits can also cause the exotherm that can irreversibly degrade V-SCR catalyst performance. Therefore carbonaceous deposit mitigation strategies, based on their characterization, are needed to minimize their impact on performance. The nature and the amount of the deposits, formed upon exposure to real-world conditions, were primarily carried out by the controlled oxidation of the deposits to classify these carbonaceous deposits into three major classes of species: i) HCs, ii) coke, and iii) soot. The reversible NOx conversion degradation can be largely correlated to coke, a major constituent of the deposit, and to soot which causes face-plugging that leads to decreased catalyst accessibility.
2016-04-05
Technical Paper
2016-01-0920
Bradford A. Bruno, Ann M. Anderson, Mary Carroll, Thomas Swanton, Paul Brockmann, Timothy Palace, Isaac A. Ramphal
Abstract Aerogels are nanoporous structures with physical characteristics that make them promising for use in automotive exhaust catalysis systems: highly porous with low densities (<0.1 g/mL) and high surface area per unit mass (>300 m2/g) - features that provide favorable characteristics for catalysis of gaseous pollutants. Ceramic aerogels are also highly thermally insulating (∼0.015 W/mK) and able to withstand high temperatures. Aerogels can be made of a wide variety of ceramics (e.g. alumina, silica, titania) with other catalytically active metals (e.g. copper, cobalt, nickel) incorporated into their structures. This paper provides a brief overview of the rapid supercritical extraction (RSCE) method employed in this work for aerogel preparation, describes in detail the benchtop scale testbed and methods used to assess the catalytic activity of RSCE fabricated aerogels, and presents data on the catalytic ability of some promising aerogel chemistries.
2016-04-05
Technical Paper
2016-01-0916
Nebojsa Milovanovic, Shant Hamalian
Abstract The future emission legislations for diesel passenger cars are likely to include more dynamic test cycles than we have today, such as the World harmonized Light duty Testing Cycle (WLTC) and Real Drive Emissions (RDE) in the EU and very challenging SULEV legislations in the USA. In order to meet these emission legislations and challenging CO2 targets, more complex Exhaust Gas After Treatment Systems - EGATS and corresponding calibration strategies are needed. The calibration strategies have to provide the best possible fuel consumption and NOx emissions across the entire engine map for all tested cycles. The aim of this paper is to evaluate the effect of several EGATS configurations and calibrations on tailpipe NOx and CO2 emissions of a D segment vehicle. The experimental results and potential of various EGATS configurations and calibrations for the optimisation of fuel consumption and NOx emissions are presented and discussed.
2016-04-05
Technical Paper
2016-01-0918
Alexander Sappok, Paul Ragaller, Leslie Bromberg, Vitaly Prikhodko, John Storey, James Parks
Abstract Radio frequency (RF)-based sensors provide a direct measure of the particulate filter loading state. In contrast to particulate matter (PM) sensors, which monitor the concentration of PM in the exhaust gas stream for on-board diagnostics purposes, RF sensors have historically been applied to monitor and control the particulate filter regeneration process. This work developed an RF-based particulate filter control system utilizing both conventional and fast response RF sensors, and evaluated the feasibility of applying fast-response RF sensors to provide a real-time measurement of engine-out PM emissions. Testing with a light-duty diesel engine equipped with fast response RF sensors investigated the potential to utilize the particulate filter itself as an engine-out soot sensor.
2016-04-05
Technical Paper
2016-01-0935
Gerben Doornbos, Stina Hemdal, Daniel Dahl, Ingemar Denbratt
Passive selective catalyst reduction (SCR) systems can be used as aftertreatment systems for lean burn spark ignition (SI)-engines. Their operation is based on the interaction between the engine, an ammonia formation catalyst (AFC), and an SCR catalyst. Under rich conditions the AFC forms ammonia, which is stored in the SCR catalyst. Under lean conditions, the SCR catalyst reduces the engine out NOx using the stored NH3. This study compared the ammonia production and response times of a standard three way catalyst (TWC) and a Pd/Al2O3 catalyst under realistic engine operating conditions. In addition, the relationships between selected engine operating parameters and ammonia formation over a TWC were investigated, considering the influence of both the chosen load point and the engine settings.
2016-04-05
Journal Article
2016-01-0934
Vitaly Y. Prikhodko, James E. Parks, Josh A. Pihl, Todd J. Toops
Abstract Lean gasoline engines offer greater fuel economy than the common stoichiometric gasoline engine, but the current three way catalyst (TWC) on stoichiometric engines is unable to control nitrogen oxide (NOX) emissions in oxidizing exhaust. For these lean gasoline engines, lean NOX emission control is required to meet existing Tier 2 and upcoming Tier 3 emission regulations set by the U.S. Environmental Protection Agency (EPA). While urea-based selective catalytic reduction (SCR) has proven effective in controlling NOX from diesel engines, the urea storage and delivery components can add significant size and cost. As such, onboard NH3 production via a passive SCR approach is of interest. In a passive SCR system, NH3 is generated over a close-coupled TWC during periodic slightly rich engine operation and subsequently stored on an underfloor SCR catalyst. Upon switching to lean operation, NOX passes through the TWC and is reduced by the stored NH3 on the SCR catalyst.
2016-04-05
Technical Paper
2016-01-0937
James E. Parks, John M. E. Storey, Vitaly Y. Prikhodko, Melanie M. Debusk, Samuel A. Lewis
Abstract New regulations requiring increases in vehicle fuel economy are challenging automotive manufacturers to identify fuel-efficient engines for future vehicles. Lean gasoline direct injection (GDI) engines offer significant increases in fuel efficiency over the more common stoichiometric GDI engines already in the marketplace. However, particulate matter (PM) emissions from lean GDI engines, particularly during stratified combustion modes, are problematic for lean GDI technology to meet U.S. Environmental Protection Agency Tier 3 and other future emission regulations. As such, the control of lean GDI PM with wall-flow filters, referred to as gasoline particulate filter (GPF) technology, is of interest. Since lean GDI PM chemistry and morphology differ from diesel PM (where more filtration experience exists), the functionality of GPFs needs to be studied to determine the operating conditions suitable for efficient PM removal.
2016-04-05
Technical Paper
2016-01-0936
Anoop Reghunathan Nair, Brett Schubring, Kiran Premchand, Andrew Brocker, Peter Croswell, Craig DiMaggio, Homayoun Ahari, Jeffrey Wuttke, Michael Zammit, Michael Andrew Smith
New Particulate Matter (PM) and Particulate Number (PN) regulations throughout the world have created a need for aftertreatment solutions that include particulate control as an option to comply with the legislation. However, limitations in other criteria emissions cannot be sacrificed to accomplish the reduction of PM/PN. For this work, three-way washcoat catalyzed wall-flow Gasoline Particulate Filters (GPF) and similarly catalyzed flow-through catalysts of common defined volume were tested. Their catalytic performance was determined by measuring NOx, CO and HC conversion efficiencies and CO2 levels over the U.S. Federal Test Procedure 75 (FTP-75) and US06 Supplemental Federal Test Procedure (US06) cycles. Analysis of the impact on CO2 emissions was also evaluated in relation to backpressure from 1-D modeling analysis. All exhaust systems used the same loading and ratio of Platinum Group Metals (PGM), but employed different cell structures in their substrates.
2016-04-05
Technical Paper
2016-01-0940
Sam George, Achim Heibel
Abstract Diesel particulate filters (DPF) have become a standard aftertreatment component for a majority of current on-road/non-road diesel engines used in the US and Europe. The upcoming Stage V emissions regulations in Europe will make DPFs a standard component for emissions reductions for non-road engines. The tightening in NOx emissions standard has resulted in the use of selective catalytic reduction (SCR) technology for NOx reduction and as a result the general trend in engine technology as of today is towards a higher engine-out NOx/PM ratio enabling passive regeneration of the DPF. The novel filter concept discussed in this paper is optimized for low pressure drop, high filtration efficiency, and low thermal mass for optimized regeneration and fast heat-up, therefore reducing CO2 implications for the DPF operation.
2016-04-05
Technical Paper
2016-01-0939
Fabian Sonntag, Peter Eilts
Abstract There are numerous methods for accelerated ash loading of particulate traps known from literature. However, it is largely unknown if a combination of these methods is possible and which one generates the most similar ash compared to ash from real particulate filters. Since the influencing variables on the ash formation are not yet fully understood, ashing processes are carried out under carefully controlled laboratory conditions on an engine test bench. The first ashing takes place with low sulfated ash phosphorus and sulfur oil without any methods to increase the quantity of produced ash. The obtained ash is used as a reference and is compared hereinafter with the process examined. Four methods to increase the ash production ratio are investigated. The first one is an increase of the ash content of the lubrication oil through an increase of the additives in the oil. The second one is the additional generation of ash with a burner system where oil is injected into the flame.
2016-04-05
Technical Paper
2016-01-0927
David Culbertson, Magdi Khair, James Pradun, Henning Gero Petry, Anne Ungermann
Abstract Modifications have been made to the calibration and control of Diesel engines to increase the temperature of the exhaust especially in cold weather and part load operation. The main purpose for this advanced calibration is to enable the reduction of emissions by improving catalytic activity. An alternative method for increasing exhaust temperature is providing electric heat. Test results show the feasibility of applying various amounts of electric heat and the related increases in exhaust temperature as well as speed of heating. Simulation modeling extends the application of electric heat to a complete engine map and explores the potential impact on engine performance and emission reduction benefits.
2016-04-05
Journal Article
2016-01-0941
Christine K. Lambert, Mira Bumbaroska, Douglas Dobson, Jon Hangas, James Pakko, Paul Tennison
Abstract The purpose of this work was to examine gasoline particle filters (GPFs) at high mileages. Soot levels for gasoline direct injection (GDI) engines are much lower than diesel engines; however, noncombustible material (ash) can cause increased backpressure, reduced power, and lower fuel economy. In this study, a post mortem was completed of two GPFs, one at 130,000 mi and the other at 150,000 mi, from two production 3.5L turbocharged GDI vehicles. The GPFs were ceramic wall-flow filters containing three-way catalytic washcoat and located downstream of conventional three-way catalysts. The oil consumption was measured to be approaching 23,000 mpqt for one vehicle and 30,000 mpqt for the other. The ash contained Ca, P, Zn, S, Fe, and catalytic washcoat. Approximately 50 wt% of the collected ash was non-lubricant derived. The filter capture efficiency of lubricant-derived ash was about 50% and the non-lubricant metal (mostly Fe) deposition rate was 0.9 to 1.2 g per 10,000 mi.
2016-04-05
Technical Paper
2016-01-0926
Teuvo Maunula, Thomas Wolff, Auli Savimäki
The tightening pollutant emission limits require the use of active aftertreatment methods for NOx and particulate matter (PM). Diesel particulate filter (DPF) is a part of commercial aftertreatment system (ATS). PM accumulated in DPF is continuously passively or periodically actively regenerated with the assistance of efficient diesel oxidation catalysts (DOC) having a high efficiency and durability in hydrocarbon (HC), NO and CO oxidation reactions. A high HC concentration during fuel feeding in active regeneration is demanding for DOC. The deactivation in air, hydrothermal, sulfation and active regeneration conditions were evaluated with platinum (Pt-) and platinum-palladium (PtPd)-DOCs by laboratory simulations using the ageing temperature and time as primary variables. The oxidizing conditions with a high oxygen concentration without HCs were deactivating DOCs clearly more than active regeneration conditions with a low oxygen and high HC concentration at 700-800°C.
2016-04-05
Technical Paper
2016-01-0928
Sujay Bagi, Nishant Singh, Rob Andrew
Abstract Ash accumulation in the DPF over life results in reduced soot storage capacity, lower catalytic activity and may even alter substrate properties and lead to higher back-pressure; hence ash-cleaning of the DPF is required periodically to extend the life of the DPF and restore its catalytic performance. Several ash cleaning technologies are available which utilize pneumatic, hydraulic and wet-chemical cleaning techniques or their combinations. A batch of DPFs with various ash accumulation levels were recovered from customer field units. X-ray CT imaging was performed to understand the ash distribution in the DPF channels. Field returned DPFs were tested on Engine Dynamometer to determine the impact on overall system performance loss from fresh state. The DPFs were then cleaned using various cleaning techniques; X-ray imaging and dynamometer testing was repeated to evaluate the performance recovery.
2016-04-05
Technical Paper
2016-01-0931
Akifumi Kawakami, Yuki Fukumi, Masaaki Ito, Shingo Sokawa, Satoshi Sakashita, Mychal Taylor, Mitsuhiro Ito, Masataka Yamashita, Hirofumi Sakamoto, Hiroshi Kurachi
Abstract Honeycomb substrates are widely used to reduce harmful emissions from gasoline engines and are exposed to numerous thermal shocks during their lifetime making thermal shock resistance one of the key factors in designing honeycomb substrates. More stringent emission regulations will require the honeycomb substrates to be lighter in weight to improve light-off performance and to have better thermal shock resistance than conventional honeycomb substrates to handle higher expected temperature gradients. Thermal shock resistance is generally evaluated on a substrate by evaluating the thermal strain caused by temperature gradients inside the substrate during durability testing [1,2]. During the test, a heated substrate is cooled at a surface face to generate temperature gradients while the temperature inside the honeycomb substrate is monitored by multiple thermocouples.
2016-04-05
Technical Paper
2016-01-0933
Steve Golden, Zahra Nazarpoor, Maxime Launois, Ru-Fen Liu, Pardha Maram
Abstract In the context of evolving market conditions, the three-way catalyst (TWC) design is entering an exciting new phase. It remains the main emission control strategy for gasoline powered vehicles; in the meantime a rapid period of evolving engine developments, the constrained tailpipe regulations and the material supply issues present a unique challenge to the catalyst developers. A key approach here is to achieve highly beneficial emission performance based on the ultra-low PGM levels. In this regard, we mainly focus on the materials design and have developed the advanced spinel oxides for zero precious metals (ZPGM) and synergized precious metals (SPGM) TWCs. These advanced spinel materials showed improved thermal stability compared to that of PGM based standard materials. Fundamental studies on the microstructure of spinel oxide with newly developed composition confirm the aging stability.
2016-04-05
Technical Paper
2016-01-0932
Masanori Hashimoto, Yoshiyuki Nakanishi, Hiroshi Koyama, Syouji Inose, Hiroki Takeori, Takayuki Watanabe, Takeshi Narishige, Tatsuya Okayama, Yukio Suehiro
Abstract Engine technologies using efficient combustion and down-sizing turbo have become important in order to reduce automotive CO2 emissions. However, the exhaust gas temperature also becomes lower by these technologies. As a result, the catalyst performance becomes lower. Therefore it is necessary to develop low temperature active catalysts to reduce emissions. This research was focused on Pd/CeO2, and it’s able to oxidize CO at low temperatures. In order to increase the catalyst activity, the addition of some elements to the CeO2 was studied. Zn addition was found to have an advantage to reduce the CO light off temperature by 60 °C. Then, we tried to clarify the cause of improvement. As a result, it made clear that the Zn addition promotes the active oxygen release from the CeO2 surface. However, repeated engine exhaust gas tests indicated a decline in purification performance.
2016-04-05
Technical Paper
2016-01-0953
Homayoun Ahari, Michael Smith, Michael Zammit, Brad Walker
In order to meet LEV III, EURO 6C and Beijing 6 emission levels, Original Equipment Manufacturers (OEMs) can potentially implement unique aftertreatment systems solutions which meet the varying legislated requirements. The availability of various washcoat substrates and PGM loading and ratio options, make selection of an optimum catalyst system challenging, time consuming and costly. Design for Six Sigma (DFSS) methodologies have been used in industry since the 1990s. One of the earliest applications was at Motorola where the methodology was applied to the design and production of a paging device which Consumer Reports called “virtually defect-proof”.[1] Since then, the methodology has evolved to not only encapsulate complicated “Variation Optimization” but also “Design Optimization” where multiple factors are in play. In this study, attempts are made to adapt the DFSS concept and methodology to identify and optimize a catalyst for diesel applications.
2016-04-05
Technical Paper
2016-01-0954
Jason Jacques, Thomas Pauly, Michael Zammit, Homayoun Ahari, Michael Smith
Significant reduction in Nitrogen Oxide (NOx) emissions will be required to meet LEV III Emissions Standards for Light Duty Diesel passenger vehicles (LDD). As such, Original Equipment Manufacturers (OEMs) are exploring all possible aftertreatment options to find the best balance between performance, robustness and cost. The primary technology adopted by OEMs in North America to achieve low NOx levels is Selective Catalytic Reduction (SCR) catalyst. The critical parameters needed for SCR to work properly are: an appropriate reductant such as ammonia (NH3) typically provided as urea, adequate operating temperatures, and optimum Nitrogen Dioxide (NO2) to NOx ratios (NO2/NOx). The NO2/NOx ratio is mostly influenced by Precious Group Metals (PGM) containing catalysts located upstream of the SCR catalyst. Different versions of zeolite based SCR technologies are available on the market today and these vary in their active metal type (iron, copper, vanadium), and/or zeolite type.
2016-04-05
Journal Article
2016-01-0956
Amin Reihani, Benjamin Corson, John W. Hoard, Galen B. Fisher, Evgeny Smirnov, Dirk Roemer, Joseph Theis, Christine Lambert
Abstract Lean NOx Traps (LNTs) are one type of lean NOx reduction technology typically used in smaller diesel passenger cars where urea-based Selective Catalytic Reduction (SCR) systems may be difficult to package . However, the performance of lean NOx traps (LNT) at temperatures above 400 C needs to be improved. The use of Rapidly Pulsed Reductants (RPR) is a process in which hydrocarbons are injected in rapid pulses ahead of a LNT in order to expand its operating window to higher temperatures and space velocities. This approach has also been called Di-Air (diesel NOx aftertreatment by adsorbed intermediate reductants) by Toyota. There is a vast parameter space which could be explored to maximize RPR performance and reduce the fuel penalty associated with injecting hydrocarbons. In this study, the mixing uniformity of the injected pulses, the type of reductant, and the concentration of pulsed reductant in the main flow were investigated.
2016-04-05
Journal Article
2016-01-0957
Patrick Schrangl, Roman Schmied, Stephan Stadlbauer, Harald Waschl, Luigi del Re, Bernhard Ramsebner, Christoph Reiter
Abstract Abatement and control of emissions from passenger car combustion engines have been in the focus for a long time. Nevertheless, to address upcoming real-world driving emission targets, knowledge of current engine emissions is crucial. Still, adequate sensors for transient emissions are seldom available in production engines. One way to target this issue is by applying virtual sensors which utilize available sensor information in an engine control unit (ECU) and provide estimates of the not measured emissions. For real-world application it is important that the virtual sensor has low complexity and works under varying conditions. Naturally, the choice of suitable inputs from all available candidates will have a strong impact on these factors. In this work a method to set up virtual sensors by means of design of experiments (DOE) and iterative identification of polynomial models is augmented with a novel input candidate selection strategy.
2016-04-05
Journal Article
2016-01-0961
Satish Narayanan Ramachandran, Gillis Hommen, Paul Mentink, Xander Seykens, Frank Willems, Frank Kupper
Abstract Heavy-duty diesel engines are used in a wide range of applications. For varying operating environments, the engine and aftertreatment system must comply with the real-world emission legislation limits. Simultaneously, minimal fuel consumption and good drivability are crucial for economic competitiveness and usability. Meeting these requirements takes substantial development and calibration effort, and complying with regulations results in a trade-off between emissions and fuel consumption. TNO's Integrated Emission Management (IEM) strategy finds online, the cost-optimal point in this trade-off and is able to deal with variations in operating conditions, while complying with legislation limits. Based on the actual state of the engine and aftertreatment system, an optimal engine operating point is computed using a model-based optimal-control algorithm.
2016-04-05
Technical Paper
2016-01-0960
Arifumi Matsumoto, Kenji Furui, Makoto Ogiso, Toru Kidokoro
Abstract Urea selective catalytic reduction (SCR) systems are a promising technology for helping to lower NOx emissions from diesel engines. These systems also require on-board diagnostic (OBD) systems to detect malfunctioning catalysts. Conventional OBD methodology for a SCR catalyst involves the measurement of NOx concentration downstream of the catalyst. However, considering future OBD regulations, erroneous diagnostics may occur due to variations in the actual environment. Therefore, to enhance OBD accuracy, a new methodology was examined that utilizes NH3 slip as a new diagnostic parameter in addition to NOx. NH3 slip increases as the NOx reduction performance degrades, because both phenomena are based on deterioration in the capability of the SCR catalyst to adsorb NH3. Furthermore, NH3 can be measured by existing NOx sensors because NH3 is oxidized to NO internally. To make use of NH3 slip, an estimation model was developed.
2016-04-05
Technical Paper
2016-01-0962
Sadashiva Prabhu S, Nagaraj S Nayak, N. Kapilan
Selective Catalytic Reduction (SCR) is a most promising technique for reduction of nitrogen oxides (NOx) emitted from the exhaust of diesel engines. Urea Water Solution (UWS) is injected to hot exhaust gas stream to generate reducing agent ammonia. The droplet evaporation of Urea Water Solution (UWS) is investigated for single droplet in heated environment ranging temperatures 373K-873K theoretically. The theoretical methods which are implemented into CFD code Fire 8.3 from AVL Corp. involve Rapid Mixing model and Diffusion Limit model which consider stationary droplet and variable properties of the UWS. The UWS droplet revealed different evaporation characteristics depending on its ambient temperatures which are numerically predicted by simulated results. The simulated results are validated with experimental values of Wang et al. [9] which are helpful in predicting the evaporation and UWS dosing strategy at different exhaust gas temperatures in real SCR system.
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