Browse Topic: Lean NOx traps

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Studying the Lean Burn Operation in Two-Wheelers to Increase Fuel Efficiency and Investigate the Use of Lean NOx Trap Catalyst (LNT) for Lean Burn System2024-32-005804/18/2025
This study offers an overview of the impact of lean burn technology in two-wheeler vehicles, specifically concentrating on enhancing the fuel economy and addressing the challenges associated with its adoption. Lean burn systems, characterized by a fuel-air mixture with a higher air content than stoichiometric ratio. The study focuses on technology which meets stringent emission standards while enabling the optimization of fuel efficiency. The lean burn system employs strategies to optimize air-fuel ratio using electronic fuel injection, ignition timing control, and advanced engine control algorithms like - updated torque modulation control algorithm for drivability, lambda control algorithm for rich and lean switch and NOx modelling algorithm for LNT catalyst efficiency tracking. The challenges related to lean burn systems, includes issues related to combustion stability, nitrogen oxide (NOx) emissions, and their impact on drivability, is summarized in the study. Mitigation strategies
Somasundaram, Karthikeyan, Sivaji, Purushothaman, John Derin, C, Vishal, Karwa, Manoj Kumar, S, Maynal, Rajesh
Optimization strategies to enhance system performance with aged LNT on SUV2024-26-003501/16/2024
Diesel oxidation catalysts (DOC) combined with NOx adsorbers and passive selective catalytic reduction (SCR) systems have demonstrated effectiveness in achieving high conversion efficiencies for CO, HC, and NOx emissions. This integrated exhaust after-treatment system has shown its efficiency in meeting the demanding BS6 Real Driving Emissions (RDE) standards. However, the assessment of emissions at the end of the system's life reveals a decrease in the conversion efficiency of aged exhaust systems, particularly affecting NOx, HC and CO emissions. Factors such as thermal aging and catalyst poisoning are identified as key contributors to the degradation of the after-treatment performance. This paper elucidates correlation methodologies applied to aged Lean NOx Trap (LNT) exhaust after-treatment systems. These methodologies aid in understanding the aging behavior of LNT samples and devising strategies to enhance the emissions performance aged samples during the end-of-life tests. A dual
Shangar Ramani, Vagesh, Kashelkar, Vibhav, Bhale, Aniket, Subramanian, Senthilnathan, Mani, Saurabh
RDE Plus - A Road to Rig Development Methodology for Whole Vehicle RDE Compliance: Overview2020-01-037604/14/2020
To aid Original Equipment Manufacturers (OEM) in meeting Real Driving Emissions (RDE) regulation criteria [1] across the moderate and extended boundary conditions of temperature, altitude and driving style, an integrated Road to Rig (R2R) whole vehicle development, calibration and verification approach known as RDE Plus (RDE+) has been developed by HORIBA. Connecting testing on the road, chassis dynamometer, Engine-in-the-Loop (EiL) and virtual testing methodologies, real world driving scenarios can be deployed by OEMs further upstream during vehicle and engine development programmes; hence reducing development timescales and costs that will otherwise inevitably increase due to RDE regulations. Reported in the current paper is a brief introduction to the baseline RDE road tests followed by replication of several real RDE cycles that cover the RDE moderate and extended boundary conditions with the vehicle driven by a robot driver on the chassis dynamometer. A HORIBA Multi-function
Roberts, Philip, Mason, Alex, Whelan, Steve, Tabata, Kunio, Kondo, Yosuke, Kumagai, Tatsuki, Mumby, Richard, Bates, Luke
Calibration and Parametric Investigations on Lean NOx Trap and Particulate Filter Models for a Light Duty Diesel Engine2020-01-065704/14/2020
To comply with the stringent future emission mandates of light-duty diesel engines, it is essential to deploy a suitable combination of emission control devices like diesel oxidation catalyst (DOC), diesel particulate filter (DPF) and DeNOx converter (LNT or SCR). Arriving at optimum size and layout of these emission control devices for a particular engine through experiments is both time and cost-intensive. Thus, it becomes important to develop suitable well-tuned simulation models that can be helpful to optimize individual emission control devices as well as arrive at an optimal layout for achieving higher conversion efficiency at a minimal cost. Towards this objective, the present work intends to develop a one-dimensional Exhaust After Treatment Devices (EATD) model using a commercial code. The model parameters are fine-tuned based on experimental data. The EATD model is then validated with experiment data that are not used for tuning the model. Subsequently, the model was used for
Bagavathy, S. Suresh, Ramesh, A, Krishnasamy, Anand, Pandian, Senthur
First-Principles Research on Adsorption of NOx on Pt Cluster and BaO Cluster Supported by γ-Al 2 O 3 (110) Surface2020-01-035704/14/2020
Lean NOx trap (LNT) is a great potential NOx abatement method for lean-burn gasoline engines in consideration of exhaust aftertreatment cost and installation space. NOx firstly is adsorbed on storage sites during the lean-burn period, then reduced to N2 under catalysis of the catalyst sites in the rich-burn phase. There must be a spillover of NOx species between both types of sites. For a better understanding of this spillover process of NOx species between Pt (as the catalytic center) and BaO sites (as storage components in commercial catalyst), this work focused on the vital first step of spillover, the adsorption of NOx on clean substrate surface (γ-Al2O3 (110) surface) and Ba\Pt cluster supported by the surface. Based on first principles software VASP (Vienna Ab-initio Simulation Package), the most stable adsorption structures of NO with Pt3 clusters and (BaO)3 clusters on carrier γ- Al2O3 (110) surface were confirmed and the adsorption energy of these structures were compared
Li, Shilong, Zhang, Yanke, zhao, Jin
Diesel Vehicle with Ultra-Low NOx Emissions on the Road2019-24-014509/09/2019
The gap between diesel vehicle emissions in laboratory tests compared to those in use has been addressed by the introduction of the Real Driving Emissions (RDE) requirements. Modern diesel technology now demonstrates low emissions on the road over a wide range of driving conditions. This paper further demonstrates that consistent low nitrogen oxide (NOx) and particle number (PN) emissions can be achieved over a wide range of driving conditions beyond Euro 6d RDE requirements, with emission control technologies combined in an integrated approach. An LNT (Lean NOx Trap) is combined with a dual-dosing SCR (Selective Catalytic Reduction) system. Low-load NOx control is achieved by the LNT in combination with a close-coupled SCR coated on the Diesel Particulate Filter (SDPF). High load conditions, on the other hand, are covered by the underfloor SCR system with a second AdBlue® injector. A P0 48V mild-hybrid system is also available to support the NOx control and to ensure good driving
Demuynck, Joachim, Favre, Cecile, Bosteels, Dirk, Bunar, Frank, Spitta, Joachim, Kuhrt, Andreas
Engine-Aftertreatment in Closed-Loop Modeling for Heavy Duty Truck Emissions Control2019-01-098604/02/2019
An engine-aftertreatment computational model was developed to support in-loop performance simulations of tailpipe emissions and fuel consumption associated with a range of heavy-duty (HD) truck drive cycles. For purposes of this study, the engine-out exhaust dynamics were simulated with a combination of steady-state engine maps and dynamic correction factors that accounted for recent engine operating history. The engine correction factors were approximated as dynamic first-order lags associated with the thermal inertia of the major engine components and the rate at which engine-out exhaust temperature and composition vary as combustion heat is absorbed or lost to the surroundings. The aftertreatment model included catalytic monolith components for diesel exhaust oxidation, particulate filtration, and selective catalytic reduction of nitrogen oxides (NOx) with urea. Both the engine and aftertreatment models have been calibrated with dynamometer measurements from a commercial 2010
Gao, Zhiming, Deter, Dean, Smith, David, Pihl, Josh, Daw, C. Stuart, Parks, James
Model-Based Approaches in Developing an Advanced Aftertreatment System: An Overview2019-01-002601/15/2019
Cummins has recently launched next-generation aftertreatment technology, the Single ModuleTM aftertreatment system, for medium-duty and heavy-duty engines used in on-highway and off-highway applications. Besides meeting EPA 2010+ and Euro VI regulations, the Single ModuleTM aftertreatment system offers 60% volume and 40% weight reductions compared to current aftertreatment systems. In this work, we present model-based approaches that were systematically adopted in the design and development of the Cummins Single ModuleTM aftertreatment system. Particularly, a variety of analytical and experimental component-level and system-level validation tools have been used to optimize DOC, DPF, SCR/ASC, as well as the DEF decomposition device. The highlights of this work can be summarized as follows: a). internal dosing is more efficient than external dosing to control HC slip; High CPSI DOCs show better HC oxidation performance at high SV due to enhanced mass transfer; b). the adopted advanced
Su, Changsheng, Brault, Joseph, Munnannur, Achuth, Liu, Z. Gerald, Milloy, Sean, Harinath, Arvind, Dunnuck, David, Federle, Ken
Experimental Analysis of LNT/DPF after Treatment System on a Passenger Car for Indian Road Condition2019-26-015501/09/2019
The Lean NOx Trap (LNT) / Diesel Particulate Filter (DPF) system has been developed as one of key technologies to comply with BS VI regulations. For DPF system it is necessary to prevent excessive soot accumulation and high temperature which can lead to eventual DPF failure. For LNT system it is necessary to maintain the NOx conversion efficiency to meet the required BS VI norms. Considering the Indian road condition a methodology was developed to evaluate the soot, de-NOx and de-SOx regeneration for development of optimized LNT/DPF system. The study was carried on >1500cc, LNT/DPF equipped Euro VI diesel passenger car to evaluate the effect of regeneration characteristics in real Indian driving condition. The study was carried on different conditions such as traffic [urban mode and rural mode] and ambient condition like temperature and weather on the regeneration behavior of LNT/DPF. A concurrent study was conducted on the regeneration frequency, timing, temperature, success rate on
Tiwari, Rahul Kumar, Balagangatharan, Balamuralitharan
Catalyst-Based BS VI Stage 2 Emission Control Solutions for Light Duty Diesel2019-26-014101/09/2019
Various types of after-treatment system for BS VI Stage 1 are being assessed for the Light Duty Diesel (LDD) segment. For BS VI Stage 2, Real Driving Emission (RDE) assessment will be newly introduced, which will require more robustness in emission control system capability. Although the detailed requirements for India BS VI stage 2 are still being discussed, a reasonable assumption is that similar systems to those being developed for Euro 6d, will work for India BS VI. This paper describes typical system designs for Euro 6d and also reveals newly developed SCRF® (Selective Catalytic Reduction Filter) based systems, which demonstrate excellent RDE emissions. In addition, newly developed Lean NOx Trap (NSC) coatings, which focus on low temperature NOx control used with SCRF® (NSC + SCRF®) also show excellent emission control capability as demonstrated in this case on the ARTEMIS Cycle. These systems have potential as promising LDD solutions for India BS VI stage 2.
Sumiya, Satoshi, Kumar, Abhishek, Wylie, James, Bergeal, David
Supervisory Controller for a Light Duty Diesel Engine with an LNT-SCR After-Treatment System2018-01-176709/10/2018
Look ahead information can be used to improve the powertrain’s fuel consumption while efficiently controlling exhaust emissions. A passenger car propelled by a Euro 6d capable diesel engine is studied. In the conventional approach, the diesel powertrain subsystem control is rule based. It uses no information of future load requests but is operated with the objective of low engine out exhaust emission species until the Exhaust After-Treatment System (EATS) light off has occurred, even if fuel economy is compromised greatly. Upon EATS light off, the engine is operated more fuel efficiently since the EATS system is able to treat emissions effectively. This paper presents a supervisory control structure with the intended purpose to operate the complete powertrain using a minimum of fuel while improving the robustness of exhaust emissions. A supervisory controller assisted by look ahead information, and using a supervisory control interface that works in concert with low level local
Velmurugan, Dhinesh, McKelvey, Tomas, Lundberg, Daniel
Impact of Demanding Low Temperature Urban Operation on the Real Driving Emissions Performance of Three European Diesel Passenger Cars2018-01-181909/10/2018
In Europe, the development and implementation of new regulatory test procedures including the chassis dynamometer (CD) based World Harmonised Light Duty Test Procedure (WLTP) and the Real Driving Emissions (RDE) procedure, has been driven by the close scrutiny that real driving emissions and fuel consumption from passenger cars have come under in recent times. This is due to a divergence between stated certification performance and measured on-road performance, and has been most pointed in the case of NOx (oxides of nitrogen) emissions from diesel cars. The RDE test is certainly more relevant than CD test cycles, but currently certification RDE cycles will not necessarily include the most extreme low speed congested or low temperature conditions which are likely to be more challenging for NOx after-treatment systems. To build understanding of the emissions and fuel consumption performance of the latest available diesel passenger cars, Concawe has conducted a study of the performance of
Williams, Rod, Andersson, Jon, Hamje, Heather, Ziman, Pauline, Kar, Kenneth, Fittavolini, Corrado, Pellegrini, Leonardo, Gunther, Garry, Oliva, Fermin, Van de Heijning, Paul
Study of an Aftertreatment System for HLSI Lean-burn Engine2018-01-094504/03/2018
Lean-burn is an effective means of reducing CO2 emissions. To date, Homogenous Lean Charge Spark Ignition (HLSI) combustion, which lowers emissions of both CO2 and NOx, has been studied. Although HLSI realizes lower emission, it is a major challenge for lean-burn engines to meet SULEV regulations, so we have developed a new aftertreatment system for HLSI engines. It consists of three types of catalysts that have different functions, as well as special engine control methods. As the first stage in achieving SULEV emissions, this study focused on enhancing performance under lean conditions. HLSI engine exhaust gases contain high concentrations of hydrocarbons, including a large amount of paraffin, which are difficult to purify, rather than low concentrations of NOx. Therefore, the key point in low emissions is to purify not only NOx, but also high concentrations of paraffin at the same time. Other issues include maintaining high performance under stoichiometry operation and reducing N2O
Takeori, Hiroki, Wada, Katsuji, Matsuo, Yuichi, Morita, Tomoko, Konomoto, Takashi, Murata, Yuichiro, Kimura, Munekazu, Miyauchi, Atsuhiro
Robust DPF Regeneration Control for Cost-Effective Small Commercial Vehicles2017-24-012309/04/2017
Small commercial vehicles (SCV) with Diesel engines require efficient exhaust aftertreatment systems to reduce the emissions while keeping the fuel consumption and total operating cost as low as possible. To meet current emission legislations in all cases, a DOC and DPF and some NOx treatment device (e,g. lean NOx trap or SCR) are required. Creating a cost-effective SCV also requires keeping the cost for the exhaust aftertreatment system as low as possible because the contribution to total vehicle cost is high. By using more sophisticated and more robust operating strategies and control algorithms, the hardware cost can be reduced. To keep the calibration effort at a low level, it is necessary to apply only algorithms which have a time-efficient calibration procedure. This paper will focus on the active regeneration of the DPF. For safe and efficient DPF regeneration, a very reliable and stable DOC out temperature control is required. DOC characteristics and design are often limited by
Eck, Christopher, Nakano, Futoshi
Technology Challenges and Strategies for BS-VI in Commercial Vehicles2017-28-193707/10/2017
Air Pollution is a major concern in our country due to which Indian Government has taken a decision to move from BS-IV to BS-VI which is nearly 90% reduction in NOx and 50% in particulate matter along with addition of particulate number regulation for BS-VI in comparison to BS-IV norms in very short span of time. Vehicle manufacturers are also having the challenge to produce low cost and fuel efficient product with BS-VI solution in order to meet tightening emission regulations and increasing needs of lower fuel consumption. Detailed study is done with different approaches to meet BS-VI emission which is elaborately explained in different aspect of engine design and after treatment parameter with its pros and cons. After Treatment selection plays an important role in engine development to meet stringent emission legislations and customer demands. Strategies for BS-VI were described with the advantage and drawbacks for after treatment selection. The cost of after treatment and its
Barman, Jyotirmoy, Arora, Prateek, Patchappalam, Kumar
Performance Studies and Correlation between Vehicle- and Rapid- Aged Commercial Lean NOx Trap Catalysts2017-01-094003/28/2017
Even though substantial improvements have been made for the lean NOx trap (LNT) catalyst in recent years, the durability still remains problematic because of the sulfur poisoning and sintering of the precious metals at high operating temperatures. Hence, commercial LNT catalysts were aged and tested in order to investigate their performance and activity degradation compared to the fresh catalyst, and establish a proper correlation between the aging methods used. The target of this study is to provide useful information for regeneration strategies and optimize the catalyst management for better performance and durability. With this goal in mind, two different aging procedures were implemented in this investigation. A catalyst was vehicle-aged in the vehicle chassis dynamometer for 100000 km, thus exposed to real conditions. Whereas, an accelerated aging method was used by subjecting a fresh LNT catalyst at 800 °C for 24 hours in an oven under controlled conditions. Engine dynamometer
De Abreu Goes, Jesus Emmanuel, Olsson, Louise, Berggrund, Malin, Kristoffersson, Annika, Gustafson, Lars, Hicks, Mikael
NO 2 /NOx Ratio and NH 3 Storage Estimation of Automotive SCR Multi-Brick Systems2017-01-097203/28/2017
Many control approaches for selective catalytic reduction (SCR) systems require knowledge of ammonia storage (NH3 storage) to dose urea accurately. Currently there are no technologies to directly measure internal NH3 storage in a vehicle, so it can only be inferred from hardware sensors located upstream, downstream, or in the catalyst. This paper describes an application of extended Kalman filter (EKF) state estimator used as a virtual sensor for urea injection control of a multi-brick aftertreatment system. The proposed estimator combines mean-value physics-based models of combined SCR and diesel particulate filter (SCR/DPF), SCR and clean-up catalyst (CUC). It uses hardware sensors at the inlet and outlet of the aftertreatment system, and includes no sensors between the catalysts. Performance of the proposed estimator was validated in simulations against a high-fidelity model of the aftertreatment system. The algorithm provides accurate estimates of the dominant gaseous species NOx
Figura, Jiri, Pekar, Jaroslav, Krejza, Pavel, Mracek, David, von Wissel, Dirk, Zhang, Tianran
Development of Advanced Ultra-Low PGM DOC for BS VI DOC+CDPF+SCR System2017-26-014201/10/2017
Stricter regulatory standards are continuously adopted worldwide to control heavy duty emissions, and at the same time, fuel economy requirements have significantly lowered exhaust temperatures. The net result is a significant increase in Precious Group Metal (PGM) usage with current Diesel Oxidation Catalyst (DOC) technology. Therefore, the design and development of advanced DOC with ultra-low PGM to achieve highly beneficial emission performance improvement is necessary. The advanced DOC is synergized PGM (SPGM) with Mixed Metal Oxide (MMO). The presence of MMO in SPGM is responsible for NO oxidation to NO2 which is critical for the passive regeneration of the downstream filter and SCR function. This paper outlines the development of MMO for application in modern DOCs and addresses some specific challenges underlying this application. Lab and flow reactor data demonstrates MMO by itself owns great oxidation properties with high surface area available for NO oxidation reaction. In
Nazarpoor, Zahra, Golden, Steve, Liu, Ru-Fen
Development of Advanced Ultra-Low PGM DOC for BS VI DOC+CDPF+SCR System2017-26-0142-TEST-REC01/10/2017
Stricter regulatory standards are continuously adopted worldwide to control heavy duty emissions, and at the same time, fuel economy requirements have significantly lowered exhaust temperatures. The net result is a significant increase in Precious Group Metal (PGM) usage with current Diesel Oxidation Catalyst (DOC) technology. Therefore, the design and development of advanced DOC with ultra-low PGM to achieve highly beneficial emission performance improvement is necessary. The advanced DOC is synergized PGM (SPGM) with Mixed Metal Oxide (MMO). The presence of MMO in SPGM is responsible for NO oxidation to NO2 which is critical for the passive regeneration of the downstream filter and SCR function. This paper outlines the development of MMO for application in modern DOCs and addresses some specific challenges underlying this application. Lab and flow reactor data demonstrates MMO by itself owns great oxidation properties with high surface area available for NO oxidation reaction. In
Nazarpoor, Zahra, Golden, Steve, Liu, Ru-Fen
Analysis of a Diesel Passenger Car Behavior On-Road and over Certification Duty Cycles2016-01-232810/17/2016
Precise, repeatable and representative testing is a key tool for developing and demonstrating automotive fuel and lubricant products. This paper reports on the first findings of a project that aims to determine the requirements for highly repeatable test methods to measure very small differences in fuel economy and powertrain performance. This will be underpinned by identifying and quantifying the variations inherent to this specific test vehicle, both on-road and on Chassis Dynamometer (CD), that create a barrier to improved testing methods. In this initial work, a comparison was made between on-road driving, the New European Drive Cycle (NEDC) and World harmonized Light-duty Test Cycle (WLTC) cycles to understand the behavior of various vehicle systems along with the discrepancies that can arise owing to the particular conditions of the standard test cycles. The engine controller of a 2.0L diesel vehicle with active de-NOx and a particulate filter (DPF) has been monitored over
Chappell, Edward, Burke, Richard, Lu, Pin, Gee, Michael, Williams, Rod
Development of Ultra-Low Synergized PGM as Diesel Oxidation Catalyst for Heavy-Duty Applications2016-01-232110/17/2016
Stricter regulatory standards are continuously adopted worldwide to control heavy duty emissions, and at the same time, fuel economy requirements have significantly lowered exhaust temperatures. The net result is a significant increase in Precious Group Metal (PGM) usage with current Diesel Oxidation Catalyst (DOC) technology. Therefore, the design and development of synergized precious metal (SPGM) in which ultra-low PGM is synergized with mixed metal oxide (MMO) to achieve highly beneficial emission performance improvement, is necessary. The presence of MMO in SPGM is responsible for NO oxidation to NO2 which is critical for the passive regeneration of the downstream filter and SCR function. This paper presents an initial study outlining the development of MMOs for application in modern DOCs and addresses some specific challenges underlying this application. Lab and flow reactor data in this study demonstrated SPGM DOCs thermal resistance and sulfur poisoning resistance. In addition
Nazarpoor, Zahra, Golden, Steve, Launois, Maxime, Kitazumi, Sen, Xie, Dianyong, McConnell, Campbell
Analysis of a Diesel Passenger Car Behavior On-Road and over Certification Duty Cycles2016-01-2328-TEST-REC10/17/2016
Precise, repeatable and representative testing is a key tool for developing and demonstrating automotive fuel and lubricant products. This paper reports on the first findings of a project that aims to determine the requirements for highly repeatable test methods to measure very small differences in fuel economy and powertrain performance. This will be underpinned by identifying and quantifying the variations inherent to this specific test vehicle, both on-road and on Chassis Dynamometer (CD), that create a barrier to improved testing methods. In this initial work, a comparison was made between on-road driving, the New European Drive Cycle (NEDC) and World harmonized Light-duty Test Cycle (WLTC) cycles to understand the behavior of various vehicle systems along with the discrepancies that can arise owing to the particular conditions of the standard test cycles. The engine controller of a 2.0L diesel vehicle with active de-NOx and a particulate filter (DPF) has been monitored over
Chappell, Edward, Burke, Richard, Lu, Pin, Gee, Michael, Williams, Rod
Rapidly Pulsed Reductants in Diesel NOx Reduction by Lean NOx Traps: Effects of Mixing Uniformity and Reductant Type2016-01-095604/05/2016
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. We found that all of these parameters are important for
Reihani, Amin, Corson, Benjamin, Hoard, John W., Fisher, Galen B., Smirnov, Evgeny, Roemer, Dirk, Theis, Joseph, Lambert, Christine
Impact of Rh Oxidation State on NOx Reduction Performance of Multi-Component Lean NOx Trap (LNT) Catalyst2016-01-094704/05/2016
Typical Lean NOx Trap (LNT) catalyst composition includes precious metal components (Pt, Pd, and/or Rh), responsible for NO oxidation during lean operation and NOx reduction during rich operation. It was found that redox history of commercial LNT catalyst plays a significant role on deciding its NOx conversion under Lean/Rich cyclic condition. Further test had shown that fully formulated LNT catalyst being pre-reduced had shown much better NO reduction activity during the temperature-programmed reduction (TPRx) of NO than the same LNT catalyst being oxidized. The following study with Rh-only and Pt-only catalyst had demonstrated that Rh plays a key role on the large variation of the NO reduction function due to oxidation state change over LNT catalyst. Kinetic analysis of the NO reduction was performed in an attempt to elucidate the underlying mechanistic relationship, where it was found that NO reduction over reduced Rh can be well described by an Arrhenius equation with first-order
Li, Junhui, Currier, Neal, Yezerets, Aleksey, Chen, Hai-Ying, Hess, Howard, Mulla, Shadab
Adapting Design for Six Sigma (DFSS) Methodology for Diesel Lean NOx Trap (LNT) Catalyst Screening2016-01-095304/05/2016
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. Lean NOx Trap (LNT) was selected
Ahari, Homayoun, Smith, Michael, Zammit, Michael, Walker, Brad
Virtual Test of Manufacturing Process Effect on Injector Design2015-01-279409/29/2015
Diesel exhaust after treatment solutions using injection, such as urea-based SCR and lean NOx trap systems, effectively reduce the emission NOx level in various light vehicles, commercial vehicles, and industrial applications. The performance of the injector is crucial for successfully utilizing this type of technology, and a simulation tool plays an important role in the virtual design, that the performance of the injector is evaluated to reach the optimized design. The virtual test methodology using CFD to capture the fluid dynamics of the injector internal flow has been previously developed and validated for quantifying the dosing rate of the test injector. In this study, the capability of the virtual test methodology was extended to determine the spray angle of the test injector, and the effect of the manufacturing process on the injector internal nozzle flow characteristics was investigated using the enhanced virtual test methodology. Several variations of injector key geometric
Lu, Meng-Huang, Lacin, Figen, McAninch, Daniel, Yang, Frank
SAE Fuel Consumption Test Procedure (Engineering Method)J1526_201509 (Historical)09/17/2015
This document describes a fuel-consumption test procedure that utilizes industry accepted data collection and statistical analysis methods to determine the difference in fuel consumption between vehicles with a gross vehicle weight of more than 10,000 pounds. This test procedure can be used for an evaluation of two or more different vehicles but is not to be used to evaluate a component change. Although on-road testing is allowed, track testing is the preferred method because it has the greatest opportunity to minimize weather and traffic influences on the variability of the results. All tests shall be conducted in accordance with the weather constraints described within this procedure and shall be supported by collected data and analysis. This document provides information that may be used in concert with SAE Recommended Practices J1264, J1252, J1321, and J2966 as well as additional current and future aerodynamic and vehicle performance SAE standards.
Truck and Bus Aerodynamics and Fuel Economy Committee
Identifying Limiters to Low Temperature Catalyst Activity2015-01-102504/14/2015
The drive to more fuel efficient vehicles is underway, with passenger car targets of 54.5 mpg fleet average by 2025. Improving engine efficiency means reducing losses such as the heat lost in the exhaust gases. However, reducing exhaust temperature makes it harder for emissions control catalysts to function because they require elevated temperatures to be active. Addressing this conundrum was the focus of the work performed. The primary objective of this work was to identify low temperature limiters for a variety of catalyst aftertreatment types. The ultimate goal is to reduce catalyst light-off temperatures, and the knowledge needed is an understanding of what prevents a catalyst from lighting off, why, and how it may be mitigated. Collectively these are referred to here as low temperature limiters to catalyst activity. This paper describes the work performed to identify low temperature limiters to catalyst activity for gasoline Three Way Catalyst (TWC), Diesel Oxidation Catalyst (DOC
Bartley, Gordon J.
Next Generation All in One Close-Coupled Urea-SCR System2015-01-099404/14/2015
Diesel engines provide a solution for the reduction of carbon dioxide (CO2) from motor vehicles. For diesel engines, however, technology to reduce nitrogen oxide (NOx) emissions is essential. This report focuses on Urea - Selective Catalytic Reduction (SCR) as an aftertreatment system for NOx reduction. The NOx conversion performance of SCR catalyst depends on exhaust gas temperature and the NO2/NOX ratio. In order to raise the NO2/NOX ratio, it is essential to raise the temperature of oxidation catalyst. For these purposes, it is necessary to raise the temperature of oxidation catalyst and SCR catalyst to high level in order to enhance NOx conversion. Temperature rising is implemented by in-cylinder fuel injection (post-injection). Consequently, degraded fuel economy becomes an issue at low vehicle speeds that cannot be expected to raise the temperature in catalyst, and particularly in the case of conventional SCR system that is located under the vehicle floor (Under-Floor SCR: UF/SCR
Kojima, Hiroyuki, Fischer, Michael, Haga, Hisao, Ohya, Naoki, Nishi, Kensuke, Mito, Takuya, Fukushi, Naoko
OBD Diagnostic Strategies for LEVIII Exhaust Gas Aftertreatment Concepts2015-01-104004/14/2015
Upcoming motor vehicle emission regulations, such as California's LEVIII, continue to tighten emission limitations in diesel vehicles. These increasingly challenging emission requirements will be met by improving the combustion process (reducing engine-out emissions), as well as improving the exhaust gas aftertreatment efficiency. Furthermore, intricate On-Board Diagnostics (OBD) systems are required to properly diagnose and meet OBD regulation requirements for complex aftertreatment systems. Under these conditions, current monitoring strategies are unable to guarantee reliable detection of partially failed systems. Additionally, new OBD regulations require aftertreatment systems to be diagnosed as a whole. This paper covers potential OBD strategies for LEVIII aftertreatment concepts with regard to regulation compliance and robustness, while striving to use existing sensor concepts.
Nanjundaswamy, Harsha K., Deussen, Joel, Van Sickle, Roger, Tomazic, Dean, Szailer, Tamas, Franke, Michael, Kotter, Matthias, Koerfer, Thomas
A Study of LNT & Urea SCR on DPF System to Meet the Stringent Exhaust Emission Regulation2014-01-281010/13/2014
In diesel engine development, the new technology is coming out to meet the stringent exhaust emission regulation. The regulation demands more eco-friendly vehicles. Euro6c demands to meet not only WLTP mode, but also RDE(Real Driving Emission). In order to satisfy RDE mode, the new technology to reduce emissions should cover all operating areas including High Load & High Speed. It is a big challenge to reduce NOx on the RDE mode and a lot of DeNOx technologies are being developed. So the new DeNOx technology is needed to cover widened operating area and strict acceleration / deacceleration. The existing LNT(Lean NOx Trap) and Urea SCR(Selective Catalytic Reduction) is necessary to meet the typical NEDC or WLTP, but the RDE mode demands the powerful DeNOx technology. Therefore, the LNT & Urea SCR on DPF was developed through this study. This complex new technology consists of new catalysts(to reduce emissions), insulation(to improve fuel economy, and catalytic performance), and logical
Joo, Kihyung, Park, Jin Woo, Lee, Jin-ha, Kim, Seok-Jae, Yoo, Seungbeom
Virtual Test of Injector Design Using CFD2014-01-235109/30/2014
Diesel exhaust aftertreatment solutions using injection, such as urea-based SCR and lean NOx trap systems, effectively reduce the emission NOx level in various light vehicles, commercial vehicles, and industrial applications. The performance of the injector plays an important role in successfully utilizing this type of technology, and the CFD tool provides not only a time and cost-saving, but also a reliable solution for extensively design iterations for optimizing the injector internal nozzle flow design. Inspired by this fact, a virtual test methodology on injector dosing rate utilizing CFD was proposed for the design process of injector internal nozzle flows. For a low-pressure (less than 6 bar) injector application, the characteristic Reynolds number based on the diameter and mass flow rate of the inlet, return flow outlet, and nozzle exit of the injector might range from 2000 to 20000, therefore, employing a flow-physics based viscous model for building up a virtual test
Lu, Meng-Huang, Lacin, Figen, McAninch, Daniel, Yang, Frank
Development and Implementation of a Mapless, Model Based SCR Control System2014-01-905007/01/2014
Various engine platforms employ Selective Catalytic Reduction (SCR) technology to reduce the tail pipe emissions of oxides of nitrogen (NOx) from diesel engines as part of an overall strategy to comply with the emission regulations in place in various countries. High levels of NOx conversion (greater than 98%) in SCR aftertreatment may provide operating margin to increase overall fuel efficiency. However, to realize the potential fuel efficiency gains, the SCR technology employed should achieve high NOx conversion with limited reductant slip over transient application cycles in addition to steady state operation. A new approach to SCR controls was developed and implemented. This approach does not rely on any maps to determine the amount of urea solution to be dosed, thus significantly reducing calibration and development time and effort when implementing the SCR technology on multiple engine platforms and applications. In addition, the controls technique is completely model based and
Chavannavar, Praveen
Development of New Lean NOx Trap Technology with High Sulfur Resistance2014-01-152604/01/2014
In this study several NOx storage materials have been investigated to see their NOx storage properties. And sulfur release properties of these materials have been also investigated. Based on these findings, new LNT catalyst was developed. In this new LNT catalyst Barium is supported on one basic material, and Strontium is coated in the whole catalyst with high dispersion. And it shows higher NOx storage performance against conventional LNT one even though 10g/L of sulfur was introduced to the catalysts. According to analysis results of new LNT catalyst after sulfur poisoning, it was found that sulfur was mainly adsorbed on Strontium selectively, and then it formed sulfate compound as SrSO4. On the other hand, another sulfate compounds could be hardly observed. And regarding Barium on basic material some analysis measurement said that it has not only better NOx storage function, but also better sulfur release function. The assumption why new LNT catalyst has high sulfur resistance is
Umeno, Takahiro, Hanzawa, Masaya, Hayashi, Yoshiyuki, Hori, Masao
Secondary Fuel Injection Characterization of a Diesel Vaporizer for Active DPF RegenerationSAE-PAPER-2014-01-149404/01/2014
Secondary fuel injection is applied to facilitate active soot management of the particulate filter within diesel aftertreatment systems, avoiding concerns with fuel delivery via in-cylinder post-injection. System performance is dependent on the thermo-fluid interactions of the injected fuel with the exhaust stream, with the intent of having more fully vaporized fuel and a well-mixed air-fuel mixture at the inlet of the oxidation catalyst for uniform thermal distribution as it exothermically reacts. Pre-heating the fuel with a diesel vaporizer prior to its delivery into the exhaust enables improved system performance, reducing droplet sizes and mixing demands. A diesel vaporizer is applied within the exhaust of a medium duty truck application, and the response of the catalyst is characterized across a variety of conditions. Cross-sectional measurements at the catalyst and filter outlet are described, including gas velocity, temperature, and HC concentration, and the effect of poor fuel
Hein, Eric, Kotrba, Adam, Inclan, Tobias, Bright, Andrew
Catalytic NOx Control Technologies for Diesel & GDI Engines Web Seminar RePlayPD331237ON03/05/2014
Lean burn engines (diesel and GDI) boast higher fuel economy and cleaner emissions than conventionally tuned engines while producing equivalent power. They employ higher combustion chamber compression ratios, significant air intake swirl and precise lean-metered direct fuel injection. The downfall of lean-burn technology, however, is increased exhaust NOx emissions (due to higher heat and cylinder pressure) and a somewhat narrower RPM power-band (due to slower burn rates of lean mixtures). Removal of NOx from exhausts is a critical need for emission standards and ambient ozone requirements. This three session web seminar will examine the various catalytic processes for lean burn applications, including Selective Catalytic NOx Reduction (SCR), NOx Trap Technologies (i.e. LNT, NSR), and the combination of SCR, NOx Trap and Hydrocarbon NOx Reduction (LNC). It will focus in on SCR NOx fundamentals, equipping participants with the basic concepts for NOx control and important design
De-NOx Performance of Combined System of Reforming Catalyst and LNT for a DME Engine2013-01-259210/14/2013
Dimethyl ether(DME) is easily reformed into H2, since the chemical structure of DME does not feature direct C-C bonds, in contrast to diesel fuel. We have researched reforming catalysts for effectively generating H2 from the exhaust gases of a DME engine. The objective of this study is to evaluate the de-NOx performance of a combined system of RC(Reforming Catalyst) and LNT(Lean NOx Trap) for a DME engine according to reforming catalysts. The H2 generation of the reforming catalyst was observed under various conditions. CAT-A, CAT-B and CAT-C were prepared as reforming catalysts, and OC(Oxidation Catalyst) and LNT (Lean NOx Trap) were examined as commercial catalysts. The CAT-A catalyst has a higher amount of acid sites compared to the CAT-B and CAT-C catalysts. The CAT-A which is a mixing of mordenite and γ-Al2O3, has the highest H2 yield. However, the H2 yield decreased in the reforming reaction when CO2, NO and O2 coexisted. The NOx conversions of the combined system of fresh and
Choi, Byung-Chul, Park, Syungyong, Lee, Young-Jae
Comparative Urban Drive Cycle Simulations of Light-Duty Hybrid Vehicles with Gasoline or Diesel Engines and Emissions Controls2013-01-158504/08/2013
We summarize results from comparative simulations of hybrid electric vehicles with either stoichiometric gasoline or diesel engines. Our simulations utilize previously published models of transient engine-out emissions and models of aftertreatment devices for both stoichiometric and lean exhaust. Fuel consumption and emissions were estimated for comparable gasoline and diesel light-duty hybrid electric vehicles operating over single and multiple urban drive cycles. Comparisons between the gasoline and diesel vehicle fuel consumptions and emissions were used to identify potential advantages and technical barriers for diesel hybrids.
Gao, Zhiming, Daw, C. Stuart, Smith, David E.
DOC Temperature Control for Low Temperature Operating Ranges with Post and Main Injection Actuation2013-01-158004/08/2013
In a typical diesel engine exhaust aftertreatment system consisting of a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF) and a selective catalytic reduction (SCR) system the main purpose of the DOC, besides the oxidation of CO to CO₂, is the oxidation of NO to NO₂. The NO to NO₂ conversion is an essential contribution for the downstream SCR system because the fast SCR reaction which provides the highest conversion rates of NOx to H₂O and N₂ works well only under roughly equal concentrations of NO and NO₂. The typical amount of NO to NOx ratio produced by the engine is about 0.95, hence the DOC is necessary to decrease this coefficient close to 0.50. Due to the temperature dependency of the DOC reaction mechanism the oxidation of NO to NO₂ takes only place sufficiently if the temperature of the DOC is higher than 200°C, which, however, cannot be reached during low engine speed and low load situations. As a consequence, under these circumstances the whole reduction
Stadlbauer, Stephan, Waschl, Harald, Schilling, Alexander, del Re, Luigi
Adaptive Temperature Control for Diesel Particulate Filter Regeneration2013-01-051704/08/2013
The regeneration process of a Diesel Particulate Filter (DPF) consists of an increase in the engine exhaust gas temperature by using post injections and/or exhaust fuel injection during a period of time in order to burn previously trapped soot. The DPF regeneration is usually performed during a real drive cycle, with continuously changing driving conditions. The quantity of post injection/exhaust fuel to use for regeneration is calculated using a combination of an open loop term based on engine speed, load and exhaust gas flow and a closed loop term based on an exhaust gas temperature target and the feedback from a number of sensors. Due to the nature of the system and the slow response of the closed loop term for correcting large deviations, the authority of the fuel calculation is strongly biased to the open loop. However, the open loop fuel calculation might not be accurate enough to provide adequate temperature tracking due to several disturbances in the system. This paper
Castellano, Javier, Chaudhari, Anita, Bromham, Jim
Simulated Fuel Economy and Emissions Performance during City and Interstate Driving for a Heavy-Duty Hybrid Truck2013-01-103304/08/2013
We compare the simulated fuel economy and emissions for both conventional and hybrid class 8 heavy-duty diesel trucks operating over multiple urban and highway driving cycles. Both light and heavy freight loads were considered, and all simulations included full aftertreatment for NOx and particulate emissions controls. The aftertreatment components included a diesel oxidation catalyst (DOC), urea-selective catalytic NOx reduction (SCR), and a catalyzed diesel particulate filter (DPF). Our simulated hybrid powertrain was configured with a pre-transmission parallel drive, with a single electric motor between the clutch and gearbox. A conventional heavy duty (HD) truck with equivalent diesel engine and aftertreatment was also simulated for comparison. Our results indicate that hybridization can significantly increase HD fuel economy and improve emissions control in city driving. However, there is less potential benefit for HD hybrid vehicles during highway driving. A major factor behind
Daw, C. Stuart, Gao, Zhiming, Smith, David E., Laclair, Tim J., Pihl, Josh A., Edwards, K. Dean
Development of an Urea Supply System for the SCR Catalyst2013-26-004701/09/2013
The increase in the fuel price and more stringent regulations on greenhouse gases (CO2) make the engine compression ignition technology even more attractive in the context of internal combustion engines. This is because the modern turbocharged direct injection engines, with the common rail fuel system, are characterized by high combustion efficiency and power density, that make them particularly suitable both for applications on and off road. On the other hand, the compression ignition engines are subject to a heavy technological developments to meet the more stringent regulations on emissions of exhaust pollutants, especially PM and NOx. The adopted technologies have two main approaches, on the combustion and on the exhaust gas aftertreatment. The measures applied for combustion can reduce emissions, but with the risk of penalizing the other engine performances, such as noise, power output and fuel consumption. Instead, the technologies of exhaust gases treatment may allow the over
De Cesare, Matteo, Osbat, Giovanni, Sgatti, Stefano, Battistoni, Michele
Design of Durable Vanadium - SCR Catalyst Systems for Heavy - Duty Diesel Applications2013-26-004901/09/2013
The emission regulations for mobile applications become stricter in Euro-IV to Euro-VI levels. Carbon monoxide and hydrocarbon can be removed by efficient Diesel Oxidation Catalysts (DOC) but Particulate Matter (PM) and NOx are more demanding requiring the use of active methods (urea-SCR and DPF) which will be world-wide implemented in the 2010's. Durable, coated V-SCR catalysts are based on stabilized raw materials and tailored preparation methods. Coated V2O5/TiO2-WO3 catalysts (ceramic 300/400 cpsi and metallic 500/600 cpsi) were evaluated by laboratory and engine bench experiments. Traditional V-SCR catalysts are durable up to about 600°C and have a high efficiency at 300°C-500°C. SCR activities were tailored to be higher also at 200°C-300°C or 500°C-600°C. The use of thermal stabilizers or the vanadium loading variation enabled the changes in operation window and stability. The stabilized V-SCR catalyst kept the SCR activity also after ageing at 600°C-650°C when the reference lost
Maunula, Teuvo, Viitanen, Arto, Kinnunen, Toni, Kanniainen, Kauko
Simulation of Catalytic Oxidation and Selective Catalytic NOx Reduction in Lean-Exhaust Hybrid Vehicles2012-01-130404/16/2012
We utilize physically-based models for diesel exhaust catalytic oxidation and urea-based selective catalytic NOx reduction to study their impact on drive cycle performance of hypothetical light-duty diesel-powered hybrid and plug-in hybrid vehicles (HEVs and PHEVs). The models have been implemented as highly flexible SIMULINK block modules that can be used to study multiple engine-aftertreatment system configurations. The parameters of the NOx reduction model have been adjusted to reflect the characteristics of commercially available Cu-zeolite catalysts, which are of widespread current interest. We demonstrate application of these models using the Powertrain System Analysis Toolkit (PSAT) software for vehicle simulations, along with a previously published methodology that accounts for emissions and temperature transients in the engine exhaust. Our results illustrate that the DOC-SCR combination can reduce CO, HC and NOx emissions without creating a significant direct fuel penalty, but
Gao, Zhiming, Daw, C. Stuart, Chakravarthy, V. Kalyana
Application of Artificial Neural Networks to Aftertreatment Thermal Modeling2012-01-130204/16/2012
Accurate estimation of catalyst bed temperatures is very crucial for effective control and diagnostics of aftertreatment systems. The architecture of most aftertreatment systems contains temperature sensors for measuring the exhaust gas temperatures at the inlet and outlet of the aftertreatment systems. However, the temperature that correctly reflects the temperature of the chemical reactions taking place on the catalyst surface is the catalyst bed temperature. From the Arrhenius relationship which governs the chemical reaction kinetics occurring in different aftertreatment systems, the rate of chemical reaction is very sensitive to the reaction temperature. Considerable changes in tailpipe emissions can result from small changes in the reaction temperature and robust emissions control systems should be able to compensate for these changes in reaction temperature to achieve the desired tailpipe emissions. This paper presents an artificial neural network based model for estimating the
Chi, John Nji
Controlling Particulate Matter Emissions in Vehicles Using Different Strategies under the Heavy-Duty Test Cycle2012-01-088504/16/2012
Since 1997 in Belgium, the market share of vehicles equipped with diesel engine has grown up from 50% to nearly 80%. Most of the drivers are using diesel cars for private or company purposes and gasoline powered engine vehicles sales dropped dramatically since then. This evolution is clearly a game-changer regarding the type of regulated emissions we can find as dominant. Tests and analysis for this work focused on diesel passenger cars and one of the main drivers for that was the great demand of new cars fitted with exhaust aftertreatment devices (DPF, DOC, LBC etc.). In this paper the performance of soot filters were measured and presented, based not on the NEDC but on the heavy duty 13-Mode test cycle which emphasize mainly at low-speed driving conditions, such as all passenger cars are running currently, and is also characterized by low average engine loads and low exhaust temperatures. Two modern test cars were used and tested under the same operational conditions on a chassis
Oliveira, Luis Miguel, Savvidis, Dimitrios, Pecqueur Sr, Mark
Newly Developed Cordierite Honeycomb Substrate for SCR Coating Realizing System Compactness and Low Backpressure2012-01-107904/16/2012
Ammonia Selective Catalytic Reduction (SCR) and Lean NOx Trap (LNT) systems are key technologies to reduce NOx emission for diesel on-highway vehicles to meet worldwide tighter emission regulations. In addition DeNOx catalysts have already been applied to several commercial off-road applications. Adding the DeNOx catalyst to existing Diesel Oxidation Catalyst (DOC) and Diesel Particulate Filter (DPF) emission control system requires additional space and will result in an increase of emission system back pressure. Therefore it is necessary to address optimizing the DeNOx catalyst in regards to back pressure and downsizing. Recently, extruded zeolite for DeNOx application has been considered. This technology improves NOx conversion at low temperature due to the high catalyst amount. However, this technology has concerned about strength and robustness, because the honeycomb body is composed of catalyst. A zeolite catalyst supported by a ceramic honeycomb structure resolves the strength
Hirose, Shogo, Miyairi, Yukio, Katsube, Frank, Yuuki, Kazuya, Sakamoto, Hirofumi, Vogt, Claus, Fujii, Shuji
Characterization of a New Advanced Diesel Oxidation Catalyst with Low Temperature NO x Storage Capability for LD Diesel2012-01-037304/16/2012
Currently, two consolidated aftertreatment technologies are available for the reduction of NOx emissions from diesel engines: Urea SCR (Selective Catalytic Reduction) systems and LNT (Lean NOx Trap) systems. Urea SCR technology, which has been widely used for many years at stationary sources, is becoming nowadays an attractive alternative also for light-duty diesel applications. However, SCR systems are much more effective in NOx reduction efficiency at high load operating conditions than light load condition, characterized by lower exhaust gas temperatures. One possible solution to improve the low temperature behavior, is the use of newly developed Advanced Diesel Oxidation Catalysts (A-DOC) which are capable to store NOx at low exhaust temperatures (typical of urban driving conditions) when SCR efficiency is low, and to release the stored NOx at higher temperatures (i.e., during extra-urban driving conditions) where the urea injected is effectively forming ammonia for the subsequent
Millo, Federico, Vezza, Davide
Development of a Numerical Model to Predict the Impact of Phosphorus on Flow through Aftertreatment Components2012-01-129904/16/2012
A predictive numerical model was developed to determine the impact of phosphorus exposure on the performance of flow through aftertreatment components such as Diesel Oxidation Catalysts (DOC) or Selective Catalytic Reduction (SCR) catalysts. The model is able to successfully determine the distribution of the phosphorus over the catalyst as a function of the aging history (temperature, flow rates, oil consumption rate, phosphorus content of the oil) as well as the component properties (diameter, length, cell density, wall thickness). The model then incorporates this information regarding the distribution of phosphorus over the catalyst surface to determine the impact of the phosphorus exposure on the overall catalytic activity. The model results were successfully validated using accelerated bench aging tests for the oxidation of hydrocarbons over DOC's and NH₃ oxidation and NOx reduction over SCR catalysts. The modeling approach and methodology should, however, be readily extendable to
Chavannavar, Praveen
Designing quiet off-highway equipment12OFHD0202_0202/02/2012
OEMs and suppliers are using new materials and innovative designs to reduce NVH for both vehicle operators and the environment. Off-highway vehicles can generate a lot of noise. Many improvements are being made to engines, structures, and systems related to NVH. Whether in smaller vehicles working in urban areas and/or enclosed spaces, or in larger vehicles, quieter systems will eliminate the need for hearing protection and cut down on fatigue caused by long exposure to high noise or vibration levels.
Sniderman, Debbie
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