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Viewing 241 to 270 of 22396
Collection
2014-04-01
This technical paper collection covers DOC, HC Trap, DPF, GPF, LNT, TWC, SCR, SCRF, ammonia oxidation catalysts, hybrid or combined catalysts, urea-water solution spray dynamics, and mixture non-uniformity. Modeling aspects range from fundamental, 3D models of individual components to system level simulation, optimization, variation, degradation, and control.
Collection
2014-04-01
This technical paper collection explores advances in the creation of sustainable energy sources and their usage in the transportation sector. Topics can include research and in-production technology used to produce renewable energy sources and materials.
Collection
2014-04-01
Topics included in this technical paper collection are the integration of various diesel particulate matter (PM) and diesel Nitrogen Oxide (NOx) reduction technologies plus analogous technologies for the growing population of direct injection gasoline engines.
Collection
2014-04-01
This technical paper collection covers the complete particulate filter system. There are papers covering the DOC aging as well as the effect of high sulfur fuel on the DOC. A couple of papers study the effect of ash accumulation and two papers cover a novel new asymmetric cell design and modeling of this new design. Finally we have a paper on gasoline particulate filters.
Collection
2014-04-01
This technical paper collection focuses on the general topic of combustion engine gaseous emissions (regulated and non-regulated). This includes well-to-wheels CO2 production for alternative technologies, fuel economy and all greenhouse gas emission research. It also includes hydrocarbon species and specific NOx species production over aftertreatment devices as a result of changes in fuel specification and the inclusion of bio-derived components and consideration of secondary emissions production (slip) as a result of aftertreatment.
Technical Paper
2014-04-01
Dimitrios Savvidis, Konstantinos Bounos, Christos Loakimidis
Abstract Real world engine emissions measurements were carried out from the University of Antwerp in Belgium and more than 600 passenger cars were measured when entering and leaving two different University campuses. All measurements were done according to the European Commission Directive 2010/48/EU on roadworthiness tests for motor vehicles and their trailers. A database, including a wide variety of vehicles with completely different engine specifications and technological characteristics (engine size, emissions standards exhaust after-treatment devices etc.) has been created and various parameters influencing emissions will be examined. The influence of various parameters on NOx emissions was considered and discussed in this paper. Important conclusions have been made for diesel vehicles and presented in this work. Cold and hot start engine emissions were taken and analyzed in order to determine the percentage that NOx emission increased over the years. A comparison of different generation of cars is also included in the research.
Technical Paper
2014-04-01
Anna Fathali, Mats Laurell, Fredrik B. Ekström, Annika Kristoffersson, Bengt Andersson, Louise Olsson
Abstract The effect of various fuel-cut agings, on a Volvo Cars 4-cylinder gasoline engine, with bimetallic three-way catalysts (TWCs) was examined. Deactivation during retardation fuel-cut (low load) and acceleration fuel-cut (high load, e.g. gearshift or traction control) was compared to aging at λ=1. Three-way catalysts were aged on an engine bench comparing two fuel-cut strategies and their impact on of the life and performance of the catalysts. In greater detail, the catalytic activity, stability and selectivity were studied. Furthermore, the catalysts were thoroughly analyzed using light-off and oxygen storage capacity measurements. The emission conversion as a function of various lambda values and loads was also determined. Fresh and 40-hour aged samples showed that the acceleration fuel-cut was the strategy that had the highest contribution towards the total deactivation of the catalyst system. Also, the retardation fuel-cut was found to be detrimental to the catalyst system but not to the same extent as an acceleration fuel-cut.
Technical Paper
2014-04-01
Keiichi Hayashizaki, Mitsuru Hosoya, Hiroshi Urushibara, Hiroshi Hirabayashi, Hideki Honda, Yoichiro Nakamura
Abstract 1 To meet the Japan Post New-Long-Term (Japan 2009) emissions regulation introduced in 2009, The Hydrocarbon Selective Catalytic Reduction (HC-SCR) system for the NOx emission with a diesel fuel was chosen among various deNOx after-treatment systems (the Urea-SCR, the NOx storage-Reduction Catalyst and so on). The HC-SCR was adopted, in addition to combustion modification of diesel engine (mainly cooled EGR) as the New DPR system. The New DPR system for medium and light duty vehicles was developed as a world's first technology by Hino Motors. Advantages of the New DPR are compact to easy-to-install catalyst converter and no urea solution (DEF) injection (regardless urea infrastructure) as compared the Urea-SCR system. This study is reported to introduce the New DPR system, and to clarify the reduction effect of the Original DPR on the regulated emissions (NOx, PM, HC and CO) and emissions level of the unregulated emissions (N2O, CH4, HCHO, CH3CHO, 1,3-butadiene, benzene, Benzo[a]pyrene and NH3), based on the measurement results.
Technical Paper
2014-04-01
Yunlong Li, Yiqiang Pei, Jing Qin, Shaozhe Zhang, Yu Shang, Le Yang, Xuesong Wu
Abstract The effects of exhaust gas recirculation (EGR), late intake valve closure (LIVC) and high compression ratio (HCR) on the performance of a 1.6L multi-point injection (MPI) gasoline engine at 2000rpmwere investigated in this paper. Compared to the baseline engine, The improvement of fuel consumption is about 1.4%∼4.5% by using EGR only because of a reduction of pumping loss(PMEP). Nevertheless deterioration of combustion is introduced at the same time for high specific heat of EGR. The maximum EGR rate introduced in this system is limited by cyclic variations of indicate mean effective pressure (COVIMEP) at low load and fresh charge to achieve enough output power at high load. After combined LIVC and HCR, the improvement of fuel consumption is about 3.5%∼9.6% compared with the baseline engine at the same operation conditions because of significant PMEP reduction, increasing of effective compression ratio (ECR). LIVC&HCR&EGR can improve BSFC further, however, for getting stable combustion process and sufficient power, the combined technology is mainly suitable for medium load.
Technical Paper
2014-04-01
Shaohua Hu, Suiyun Zhang, Satya Sardar, Shiyan Chen, Inna Dzhema, Shiou-Mei Huang, David Quiros, Huaiwei Sun, Christopher Laroo, L. James Sanchez, James Watson, M.-C. Oliver Chang, Tao Huai, Alberto Ayala
Abstract The California Air Resources Board (CARB) adopted the Low Emission Vehicle (LEV) III regulations in January 2012, which lowered the particulate matter (PM) emissions standards for light-duty vehicles (LDVs) from 10 milligrams per mile (10 mg/mile) to 3 mg/mile beginning with model year (MY) 2017 and 1 mg/mile beginning with MY 2025. To confirm the ability to measure PM emissions below 1 mg/mile, a total of 23 LDVs (MY pre-2004 to 2009) were tested at CARB's Haagen-Smit Laboratory (HSL) (10 LDVs) and the United States Environmental Protection Agency's (US EPA) National Vehicle and Fuel Emissions Laboratory (NVEFL) (13 LDVs) using the federal test procedure (FTP) drive schedule. One LDV with PM emissions ranging from 0.6 - 0.8 mg/mile was tested at three CARB HSL test cells to investigate intra-lab and inter-lab variability. Reference, trip, and tunnel filter blanks were collected as part of routine quality control (QC) procedures. Reference and trip blanks showed the well-documented filter weighing and handling process had negligible impact on final test values.
Technical Paper
2014-04-01
Damien Aubagnac-Karkar, Jean-Baptiste Michel, Olivier Colin, Ludovic Noël, Nasser Darabiha
Abstract In this paper, a sectional soot model coupled to a tabulated combustion model is compared with measurements from an experimental engine database. The sectional soot model, based on the work of Vervisch-Klakjic (Ph.D. thesis, Ecole Centrale Paris, Paris, 2011) and Netzell et al. (P. Combust. Inst., 31(1):667-674, 2007), has been implemented into IFPC3D (Bohbot et al., Oil Gas Sci Technol, 64(3):309-335, 2009), a 3D RANS solver. It enables a complex modeling of soot particles evolution, in a 3D Diesel simulation. Five distinct source terms are applied to each soot section at any time and any location of the flow. The inputs of the soot model are provided by a tabulated combustion model derived from the Engine Approximated Diffusion Flame (EADF) one (Michel and Colin, Int. J. Engine Res., 2013) and specifically modified to include the minor species required by the soot model. An experimental database has been built, using both commercial Diesel fuel and the computed surrogate (30% alpha-methylnaphthalene and 70% decane in volume) to compare result between the Diesel fuel and the surrogate and to validate the models against the experiment.
Technical Paper
2014-04-01
Dongxian Song, Ning Jia, Xiangyang Guo, Xingxing Ma, Zhigang Ma, Dingwei Gao, Kejun Li, Haipeng Lai, Chunhui Zhang
Abstract Downsizing is regarded as a promising strategy to reduce the fuel consumption of gasoline engines. But downsized turbocharged engines need to take knocking into account to avoid engine damage. Low Pressure (LP) cooled exhaust gas recirculation (EGR) is an effective suppressant of knocking at boosted high load and EGR could reduce pumping loss at low loads. Both of them are helpful to improve fuel economy. In the research, a LP cooled EGR system is added to a 1.5L turbocharged PFI production gasoline engine and the compression ratio is changed from 9.3 to 11.5. The results show that the fuel reduction is 4.5% at 2000rpm 5bar (20% EGR ratio) and 9.7 % at 3000rpm 10bar (20% EGR ratio) compared with no EGR case. But at boosted high loads the fuel consumption is almost same to the production engine due to high compression ratio which results in severe knocking. In order to further reduce fuel consumption, the engine is operated in lean burn conditions. As we know, the lean operation could decrease NOX conversion efficiency of three-way catalytic (TWC), but the EGR could substantially reduce the emission of NOX.
Technical Paper
2014-04-01
Guanyu Zheng, Fengshuang Wang, Suying Zhang, Jianhua Zhang, Jianzhong Tao, Zhiguo Zhao, Jianqing Fan
Abstract In order to satisfy China IV (equivalent to EU IV) emission regulations, an unconventional design concept was proposed with injector closely coupled with SCR can body. The benefit of this design is that the urea decomposition pipe was removed or drastically shortened, resulting in much smaller packaging space and lower cost of the whole system. However, the resulting short urea mixing distance generates concerns on low urea mixing efficiency and risks of urea deposits. In particular, airless urea injectors tend to generate incomplete evaporation of urea water solution, resulting in high risks of urea deposits. New aftertreatment mixing structures need to be developed to resolve these technical challenges. To this end, stepwise and systematic enhancements of the design have been employed, resulting in multiple designs to eventually meet a set of performance targets, including emission reduction efficiency, reagent mixing, urea evaporation, ammonia and velocity distribution, back pressure, and urea deposits.
Technical Paper
2014-04-01
Susanna Paz, Rosa Delgado, David Riba
Abstract Currently, regulations on vehicle evaporative emissions only focus on the sum of Total Hydrocarbons (THC) without taking into account either the detailed hydrocarbon composition nor other chemicals besides hydrocarbons emitted from gasoline evaporation. As a consequence, this composition, also known as speciation, is not always noted and is even more unknown when biofuels such as ethanol are introduced in the market. Furthermore, these regulations do not differentiate the source of these emissions in the vehicle. The programme described in this paper is designed to investigate the influence of the addition of ethanol to gasoline on evaporative emissions. It has tried to go one step ahead of these directives obtaining more detailed characterization of these evaporative emissions. The programme has enabled a list of compounds (methanol, ethanol, aldehydes, ketones and hydrocarbons) to be determined in evaporative emissions among different ethanol-gasoline fuels (E0, E5-S, E10 and E85), applied to Euro 4 and Flexifuel vehicles by three chromatographic methods based on California Air Resources Board (CARB).
Technical Paper
2014-04-01
Fabien Redon, Christopher Kalebjian, John Kessler, Nicholas Rakovec, John Headley, Gerhard Regner, John Koszewnik
Abstract With current and pending regulations-including Corporate Average Fuel Economy (CAFE) 2025 and Tier 3 or LEV III-automakers are under tremendous pressure to reduce fuel consumption while meeting more stringent NOx, PM, HC and CO standards. To meet these standards, many are investing in expensive technologies-to enhance conventional, four-stroke powertrains-and in significant vehicle improvements. However, others are evaluating alternative concepts like the opposed-piston, two-stroke engine. First manufactured in the 1890s-and once widely used for ground, marine and aviation applications-the historic opposed-piston, two-stroke (OP2S) engine suffered from poor emissions and oil control. This meant that its use in on-highway applications ceased with the passage of modern emissions standards. Since then, Achates Power has enhanced the opposed-piston engine and resolved its historic challenges: wrist pin and power cylinder durability, piston and cylinder thermal management, piston ring integrity and oil consumption [1].
Technical Paper
2014-04-01
Xiao Ma, Yunliang Qi, Zhi Wang, Hongming Xu, Jian-Xin Wang
Abstract Using EGR instead of throttle to control the load of a stoichiometric dual-fuel dieseline (diesel and gasoline) compression ignition (SDCI) engine with three-way catalyst (TWC) aftertreatment is considered a promising technology to address the challenges of fuel consumption and emissions in future internal combustion engines. High-speed imaging is used to record the flame signal in a single-cylinder optical engine with a PFI+DI dual injection system. The premixed blue flame is identified and separated using green and blue channels in RGB images. The effects of injection timing on SDCI combustion are studied. An earlier injection strategy is found to be ideal for soot reduction; however, the ignition-injection decoupling problem results in difficulties in combustion control. It is also found that a split injection strategy has advantages in soot reduction and thermal efficiency. Only 10% of the total diesel fuel for the main injection can advance the combustion phase significantly and the combustion duration can be reduced by approximate 50%.
Technical Paper
2014-04-01
Hai Wu, Wen Chen, Meng-Feng Li, Xinlei Wang
Abstract A hot and cold water mixing process with a steam condenser and a chilled water heat exchanger is set up for an engine EGR fouling test. The test rig has water recycled in the loop of a pump, heat exchangers, a three-way mixing valve, and a test EGR unit. The target unit temperature is controlled by a heating, cooling and mixing process with individual valves regulating the flow-rate of saturated steam, chilled water and mixing ratio. The challenges in control design are the dead-time, interaction, nonlinearity and multivariable characteristics of heat exchangers, plus the flow recycle in the system. A systems method is applied to extract a simple linear model for control design. The method avoids the nonlinearity and interaction among different temperatures at inlet, outlet and flow-rate. The test data proves the effectiveness of systems analysis and modeling methodology. As a result, the first-order linear model facilitates the controller design. The simulation studies with internal recycle processes produced promising results.
Technical Paper
2014-04-01
Thomas Wolff, Ramona Deinlein, Henrik Christensen, Lars Larsen
The integration of DeNOx functionality into wall flow filters for the after treatment of diesel engine exhaust gases is a field of technology to which many publications in the recent years have drawn their attention. To integrate the needed amount of catalyst, high porous substrate materials have been developed. A drawback of the high porosity levels of 60% and higher is a significant reduction in mechanical strength. The aim of this work is to provide a new solution based on a high porous SiC material which is treated by a dual layer coating. The first layer is a nanoparticle coating which enhances the mechanical strength of the substrate. It can also be used to improve the catalytic performance and to finally decrease the loading of the second coating layer which is the active catalyst for selective catalytic reduction (SCR) of NOx with ammonia. Three different types of catalysts have been investigated as the second layer: a Fe-β-zeolite, a mixed metal oxide based on ceria and zirconia and a composition based on titania and vanadia.
Technical Paper
2014-04-01
Paul B. Dickinson, Kieran Hegarty, Nick Collings, Tashiv Ramsander
Abstract The control of NOX emissions by exhaust gas recirculation (EGR) is of widespread application. However, despite dramatic improvements in all aspects of engine control, the subtle mixing processes that determine the cylinder-to-cylinder distribution of the recirculated gas often results in a mal-distribution that is still an issue for the engine designer and calibrator. In this paper we demonstrate the application of a relatively straightforward technique for the measurement of the absolute and relative dilution quantity in both steady state and transient operation. This was achieved by the use of oxygen sensors based on standard UEGO (universal exhaust gas oxygen) sensors but packaged so as to give good frequency response (∼ 10 ms time constant) and be completely insensitivity to the sample pressure and temperature. Measurements can be made at almost any location of interest, for example exhaust and inlet manifolds as well as EGR path(s), with virtually no flow disturbance. At the same time, the measurements yield insights into air-path dynamics.
Technical Paper
2014-04-01
Yong-Wha Kim, Michiel Van Nieuwstadt, Greg Stewart, Jaroslav Pekar
Abstract This paper presents the application of model predictive control (MPC) to DOC temperature control during DPF regeneration. The model predictive control approach is selected for its advantage - using a model to optimize control moves over horizon while handling constraints. Due to the slow thermal dynamics of the DOC and DPF, computational bandwidth is not an issue, allowing for more complex calculations in each control loop. The control problem is formulated such that all the engine control actions, other than far post injection, are performed by the existing production engine controller, whereas far post injection is selected as the MPC manipulated variable and DOC outlet temperature as the controlled variable. The Honeywell OnRAMP Design Suite (model predictive control software) is used for model identification, control design and calibration. The paper includes description of the DPF regeneration process, model identification and validation results, control design and trade-off analysis and experimental validation of the controller on a Ford Superduty diesel truck.
Technical Paper
2014-04-01
Nassim Khaled, Michael Cunningham, Jaroslav Pekar, Adrian Fuxman, Ondrej Santin
Abstract In this paper we consider the issues facing the design of a practical multivariable controller for a diesel engine with dual exhaust gas recirculation (EGR) loops. This engine architecture requires the control of two EGR valves (high pressure and low pressure), an exhaust throttle (ET) and a variable geometry turbocharger (VGT). A systematic approach suitable for production-intent air handling control using Model Predictive Control (MPC) for diesel engines is proposed. Furthermore, the tuning process of the proposed design is outlined. Experimental results for the performance of the proposed design are implemented on a 2.8L light duty diesel engine. Transient data over an LA-4 cycle for the closed loop performance of the controller are included to prove the effectiveness of the proposed design process. The MPC implementation process took a total of 10 days from the start of the data collection to build a calibrated engine model all the way through the calibration of the controller over the transient drive cycle.
Technical Paper
2014-04-01
Kengo Kumano, Shiro Yamaoka
Abstract The cooled EGR system has been focused on as a method for knocking suppression in gasoline engines. In this paper, the effect of cooled EGR on knocking suppression that leads to lower fuel consumption is investigated in a turbo-charged gasoline engine. First, the cooled EGR effect is estimated by combustion simulation with a knock prediction model. It shows that the ignition timing at the knocking limit can be advanced by about 1 [deg. CA] per 1% of EGR ratio, combustion phasing (50% heat release timing) at the knocking limit can be advanced by about 0.5 [deg. CA] per 1% of EGR ratio, and the fuel consumption amount can be decreased by about 0.4% per 1% of EGR ratio. Second, the effect of cooled EGR is verified in an experimental approach. By adding inert gas (N2/CO2) as simulated EGR gas upstream of the intake pipe, the effect of EGR is investigated when EGR gas and fresh air are mixed homogeneously. As a result, the ignition timing at the knocking limit is advanced by 7 [deg.
Technical Paper
2014-04-01
Daisuke Takaki, Hirofumi Tsuchida, Tetsuya Kobara, Mitsuhiro Akagi, Takeshi Tsuyuki, Morihiro Nagamine
Abstract This paper presents a study of a cooled exhaust gas recirculation (EGR) system applied to a turbocharged gasoline engine for improving fuel economy. The use of a higher compression ratio and further engine downsizing have been examined in recent years as ways of improving the fuel efficiency of turbocharged gasoline engines. It is particularly important to improve fuel economy under high load conditions, especially in the turbocharged region. The key points for improving fuel economy in this region are to suppress knocking, reduce the exhaust temperature and increase the specific heat ratio. There are several varieties of cooled EGR systems such as low-pressure loop EGR (LP-EGR), high-pressure loop EGR (HP-EGR) and other systems. The LP-EGR system was chosen for the following reasons. It is possible to supply sufficient EGR under a comparatively highly turbocharged condition at low engine speed. It is important for knocking suppression to remove nitrogen oxides (NOx) from the EGR gas, which means using EGR gas from the catalyst downstream.
Technical Paper
2014-04-01
Zhimin Liu, David Cleary
Abstract A 2.0L twin-scroll turbocharged SIDI engine was used to evaluate low-pressure loop water-cooled external EGR at operating conditions between 1000 rpm 75 Nm and 3000 rpm 250 Nm. The engine compression ratio was increased from 9.3 to 10.9. The maximum fuel consumption reduction potential, the boost pressure requirements, and the optimized external EGR calibration were determined. Combination of higher compression ratio and external EGR achieved 5-7% better fuel economy over mid-load region when using the twin-scroll turbocharger. A similar (4-6%) better fuel economy was observed over much of the higher-load region, including peak torque condition at 1000rpm, when the required boost pressure was provided by an externally-driven auxiliary boost system (not connected to the engine). The power consumption of auxiliary boost system (supercharger loss) was estimated and considered in fuel economy assessment. The fuel consumption reduction mechanisms of EGR were also analyzed. This study shows that reduced pumping loss attributed to about 0.5% fuel consumption reduction per 10% EGR, heat loss reduction and better mixture properties offered above 2% fuel consumption reduction per 10% EGR.
Technical Paper
2014-04-01
Bernhard Kern, Stephanie Spiess, Joerg Michael Richter
Abstract With the growing awareness about the presence of fine/ultra fine particulates in the ambient air and their negative impact on climate and health, some regions of the world have started to look closer at the contribution of road traffic. Since Gasoline engines, in particular when injecting fuel directly into the combustion chamber, proved to emit relevant numbers of particulates, even hardly visible, the growing share of Gasoline DI engines and their small size of particulate emissions is a concern. To address the same, the EU has already set limits for the particulate number with EU6 from 2015 onwards. The US considers setting challenging limits by particulate mass. Since mass of ultra fine particulates is very low and difficult to measure, experts investigate if a measurement by number might better address the particular concern. The implementation of a coated Particulate Filter enables meeting not only basic demands during traditional emission test cycles. Also the particulate emissions during highly transient and high load driving conditions are reduced effectively.
Technical Paper
2014-04-01
Kazuki Nakamura, Athanasios Konstandopoulos, Margaritis Kostoglou, Toshiaki Shibata, Yuki Hashizume
Abstract Diesel particulate filters (DPFs) equipped with diesel vehicles have become indispensable components to capture the soot emitted from the engines from a viewpoint of both human health and global warming problems as well as the prevailing regulations. Meanwhile, the pressure drop caused by them leads to a direct increase of fuel consumption. In order to reduce it guaranteeing the sufficient soot filtration efficiency, we have developed the new concept of asymmetric plugging layout for the DPF design, so-called Valuable Plugging Layout (VPL), on the basis of octosquare (OS) structure and have clarified the advantage of the pressure drop reduction both experimentally and theoretically. The VPL-DPF consists of two kinds of octagonal/square inlet channels and octagonal outlet channels, and there are thought to be five filtration velocity modes as well as four kinds of soot deposit layers on each side of the inlet channel walls. No deterioration of the soot filtration performance and the reduction of the transient pressure drop of the VPL-DPF during the soot loading have been confirmed through the engine bench tests compared to those of the OS-DPF.
Technical Paper
2014-04-01
Keld Johansen, Henrik Bentzer, Arkady Kustov, Kenneth Larsen, Ton V.W. Janssens, Rasmus G. Barfod
Abstract Today, the DPF and SCR catalysts are combined sequentially in diesel exhaust systems. However, such sequential system configuration has several drawbacks: 1) large volume; 2) insufficient temperature for the SCR catalyst during cold start when DPF is placed in front of SCR; and 3) unfavorable conditions for passive soot regeneration if SCR is placed upstream of the DPF. The problems can potentially be solved by integrating the SCR catalyst into the particulate filter as one multifunctional unit. The study indicates that SCRonDPF based on Cu-zeolite type as SCR material can achieve the NOx conversion levels close to flow-through SCR catalysts for LDV (Light Duty Vehicles) using forced regenerations. Forced soot regeneration solves potential sulfur poisoning. For HDV (Heavy Duty Vehicles) applications with full managed passive soot regenerations, integration of V-based SCR formulations on DPF represents an attractive solution due to high sulfur resistance accompanied by low-temperature fuel economy.
Technical Paper
2014-04-01
Kihong Kim, Rahul Mital, Takehiro Higuchi, Seomoon Chan, Chang Hwan Kim
Abstract Diesel particulate filter (DPF) is a widely used emission control device on diesel vehicles. The DPF captures the particulate matter coming from the engine exhaust and periodically burns the collected soot via the regeneration process. There are various trigger mechanisms for this regeneration, such as distance, time, fuel and simulation. Another method widely used in the industry is the pressure drop across the filter. During calibration, relation between the pressure sensor reading and soot mass in the filter is established. This methodology is highly effective in successful DPF operation as pressure sensor is a live signal that can account for any changes in engine performance over time or any unforeseen hardware failures. On the other hand, any erroneous feedback from the sensor can lead to inaccurate soot mass prediction causing unnecessary regenerations or even needless DPF plugging concerns. A similar phenomenon was observed on certain vehicles where the DPF pressure reading jumped inexplicably leading to DPF plugging concerns.
Technical Paper
2014-04-01
Homayoun Ahari, Michael Zammit, Luis Cattani, Jason Jacques, Thomas Pauly
Abstract To meet TierII/LEVII emissions standards, light duty diesel (LDD) vehicles require high conversion efficiencies from the Aftertreatment Systems (ATS) for the removal of both Hydrocarbon (HC) and Nitrogen Oxide (NOx) species. The most populous configuration for LDD ATS have the Selective Catalytic Reduction (SCR) catalyst positioned on the vehicle behind the close coupled Diesel Oxidation Catalyst (DOC) and Catalyzed Diesel Particulate Filter (CDPF). This SCR position may require active heating measures which rely on the DOC/CDPF to provide heat through the combustion of HC and CO in the exhaust. Although DOCs are always impacted by their aging conditions, some aging conditions are shown to be both reversible and irreversible. Under continuous, high speed and high mileage conditions such as experienced in a modified Standard Road Cycle (SRC) or as it is better known, the High Speed Cycle (HSC), it is shown that the DOC's activity can deteriorate initially but significantly recover over repeated FTP-75 test cycles on fully aged catalysts.
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