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Technical Paper

Performance of Next Generation Gasoline Particulate Filter Materials under RDE Conditions

2019-04-02
2019-01-0980
In order to meet the challenging CO2 targets beyond 2020 without sacrificing performance, Gasoline Direct Injection (GDI) technology, in combination with turbo charging technology, is expanding in the automotive industry. However, while this technology does provide a significant CO2 reduction, one side effect is increased Particle Number (PN) emission. As a result, from September 2017, GDI vehicles in Europe are required to meet the stringent PN emission limits of 6x1011 #/km under the Worldwide harmonized Light vehicles Test Procedure (WLTP). In addition, it is required to meet PN emission of 9x1011 #/km under Real Driving Emission (RDE) testing, which includes a Conformity Factor (CF) of 1.5 to account for current measurement inaccuracies on the road. This introduction of RDE testing in Europe and China will especially provide a unique challenge for the design of exhaust after-treatment systems due to its wide boundary conditions.
Technical Paper

Development of Improved SCRonDPF Design for Future Tighter Regulations and Reduced System Packaging

2018-04-03
2018-01-0344
With the push towards more stringent on-road US heavy duty diesel regulations (i.e. HD GHG Phase 2 and the proposed ARB 20 mg/bhp-hr NOx), emission system packaging has grown critical while improving fuel economy and NOx emissions. The ARB regulations are expected to be implemented post 2023 while regulation for EU off-road segment will begin from 2019. The regulation, called Stage V, will introduce particle number (PN) regulation requiring EU OEMs to introduce a diesel particulate filter (DPF) while customer demands will require the OEMs to maintain current emission system packaging. A viable market solution to meet these requirements, especially for EU Stage V being implemented first, is a DPF coated with a selective catalyst reduction (SCR) washcoat (i.e. SCRonDPF).
Technical Paper

Particle Number Emission Reduction for GDI Engines with Gasoline Particulate Filters

2017-10-08
2017-01-2378
In order to meet the challenging CO2 targets beyond 2020 despite keeping high performance engines, Gasoline Direct Injection (GDI) technology usually combined with charged aspiration is expanding in the automotive industry. While providing more efficient powertrains to reduce fuel consumption one side effect of GDI is the increased particle formation during the combustion process. For the first time for GDI from September 2014 there is a Particle Number (PN) limit in EU of 6x10 sup 12 #/km, which will be further reduced by one order of magnitude to 6x10 sup 11 #/km effective from September 2017 to be the same level as applied to Diesel engines. In addition to the PN limit of the certification cycle NEDC further certification of Real Driving Emissions (RDE) including portable PN measurements are under discussion by the European Commission. RDE test procedure requires stable and low emissions in a wide range of engine operations and durable over a distance of 160 000 km.
Journal Article

Development and Testing of the Ultera® Dual Stage Catalyst System on Gasoline-Fueled Light Duty Vehicles (LDV’s)

2017-03-28
2017-01-0920
All vehicles sold today are required to meet emissions standards based on specific driving cycles. Emissions standards are getting tighter and the introduction of real driving tests is imminent, potentially calling for improved aftertreatment systems. A dual stage catalyst system, with exhaust temperature control, can provide a robust solution to meet challenging modes of operation such as rapid acceleration and other heavy-duty transients. The Ultera® technology, developed and successfully implemented on stationary natural gas CHP (Combined Heat and Power) engines, introduces a second stage catalyst downstream of a three-way catalyst. Air is injected between the two stages to provide oxygen required for the second stage reaction that removes additional CO and NMOG. Critical to the process is to avoid the reformation of NOx.
Technical Paper

Development of New High Porosity Diesel Particulate Filter for Integrated SCR Technology/Catalyst

2015-09-01
2015-01-2018
Diesel engines are widely used to reduce CO2 emission due to its higher thermal efficiency over gasoline engines. Considering long term CO2 targets, as well as tighter gas emission, especially NOx, diesel engines must become cleaner and more efficient. However, there is a tradeoff between CO2 and NOx and, naturally, engine developers choose lower CO2 because NOx can be reduced by a catalytic converter, such as a SCR catalyst. Lower CO2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher engine out NOx emission and lower exhaust gas temperatures, close-coupled a diesel particulate filter (DPF) system with integration of SCR catalyst technology is preferred. For SCR catalyst activity, it is known that the catalyst loading amount has an influence on NOx performance, so a high SCR catalyst loading will be required.
Journal Article

Development of New High Porosity Diesel Particulate Filter for Integrated SCR Technology/Catalyst

2015-04-14
2015-01-1017
Since the implementation of Euro 6 in September 2014, diesel engines are facing another drastic reduction of NOx emission limits from 180 to only 80 mg/km during NEDC and real driving emissions (RDE) are going to be monitored until limit values are enforced from September 2017. Considering also long term CO2 targets of 95 g/km beyond 2020, diesel engines must become cleaner and more efficient. However, there is a tradeoff between NOx and CO2 and, naturally, engine developers choose lower CO2 because NOx can be reduced by additional devices such as EGR or a catalytic converter. Lower CO2 engine calibration, unfortunately, leads to lower exhaust gas temperatures, which delays the activation of the catalytic converter. In order to overcome both problems, higher NOx engine out emission and lower exhaust gas temperatures, new aftertreatment systems will incorporate close-coupled DeNOx systems.
Technical Paper

Strategies Toward the Sustainable and Cost-Effective Use of the Platinum Group Metals: An Analysis of Critical Topics Affecting the PGM and Automotive Industries

2014-04-01
2014-01-1502
Platinum Group Metal (PGM) use is dominated by the automotive industry. The PGM market is sensitive to shifts in the drivers for emission control and the delicate supply-demand balance. Technology shifts in the emission control industry are particularly impactful because of the automotive market's dominance and the consequent ability to significantly affect metal prices. On the supply side, evolving ore ratios of platinum, palladium and rhodium, production ramp-up times, geopolitical factors, and labor relations contribute to a challenging production environment. This is mitigated by a growing above-ground supply from spent autocatalysts. The availability of spent autocatalyst is critical to alleviate the pressure on primary supply and is especially important in light of the hurdles primary PGM producers face. This paper reviews technology developments, legislative drivers, and consumer trends in the automotive industry and their impact on PGM demand.
Technical Paper

Influence of Material Properties and Pore Design Parameters on Non-Catalyzed Diesel Particulate Filter Performance with Ash Accumulation

2012-09-10
2012-01-1728
Diesel particulate filters (DPF) are a common component in emission-control systems of modern clean diesel vehicles. Several DPF materials have been used in various applications. Silicone Carbide (SiC) is common for passenger vehicles because of its thermal robustness derived from its high specific gravity and heat conductivity. However, a segmented structure is required to relieve thermal stress due to SiC's higher coefficient of thermal expansion (CTE). Cordierite (Cd) is a popular material for heavy-duty vehicles. Cordierite which has less mass per given volume, exhibits superior light-off performance, and is also adequate for use in larger monolith structures, due to its lower CTE. SiC and cordierite are recognized as the most prevalent DPF materials since the 2000's. The DPF traps not only combustible particles (soot) but also incombustible ash. Ash accumulates in the DPF and remains in the filter until being physically removed.
Technical Paper

Newly Developed Cordierite Honeycomb Substrate for SCR Coating Realizing System Compactness and Low Backpressure

2012-04-16
2012-01-1079
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.
Technical Paper

High Porosity DPF Design for Integrated SCR Functions

2012-04-16
2012-01-0843
Diesel engines are more fuel efficient due to their high thermal efficiency, compared to gasoline engines and therefore, have a higher potential to reduce CO2 emissions. Since diesel engines emit higher amounts of Particulate Matter (PM), DPF systems have been introduced. Today, DPF systems have become a standard technology. Nevertheless, with more stringent NOx emission limits and CO2 targets, additional NOx emission control is needed. For high NOx conversion efficiency, SCR catalysts technology shows high potential. Due to higher temperature at the close coupled position and space restrictions, an integrated SCR concept on the DPFs is preferred. A high SCR catalyst loading will be required to have high conversion efficiency over a wide range of engine operations which causes high pressure for conventional DPF materials.
Video

New Particulate Matter Sensor for On Board Diagnosis

2012-02-16
The presentation describes technology developments and the integration of these technologies into new emission control systems. As in other years, the reader will find a wide range of topics from various parts of the world. This is reflective of the worldwide scope and effort to reduce diesel exhaust emissions. Topics include the integration of various diesel particulate matter (PM) and Nitrogen Oxide (NOx) technologies as well as sensors and other emissions related developments. Presenter Atsuo Kondo, NGK Insulators, Ltd.
Technical Paper

Study on Next Generation Diesel Particulate Filter

2009-04-20
2009-01-0292
Although diesel engines are superior to gasoline engines in terms of the demand to reduce CO2 emissions, diesel engines suffer from the problem of emitting Particulate Matter (PM). Therefore, a Diesel Particulate Filter (DPF) has to be fitted in the engine exhaust aftertreatment system. From the viewpoint of reducing CO2 emissions, there is a strong demand to reduce the exhaust system pressure drop and for DPF designs that are able to help reduce the pressure drop. A wall flow DPF having a novel wall pore structure design for reducing pressure drop, increasing robustness and increasing filtration efficiency is presented. The filter offers a linear relationship between PM loading and pressure drop, offering lower pressure drop and greater accuracy in estimating the accumulated PM amount from pressure drop. First, basic experiments were performed on small plate test samples having various pore structure designs.
Technical Paper

Engine Bench and Vehicle Durability Tests of Si bonded SiC Particulate Filters

2004-03-08
2004-01-0952
Modern filter systems allow a significant reduction of diesel particulate emissions. The new silicon bonded silicon carbide particulate filters (Si-SiC filters) play an important role in this application, because they provide flexibility in terms of mean pore size and porosity and also have a high thermal shock capability to meet both engineering targets and emission limits for 2005 and beyond. Particulate filters are exposed to high temperatures and a harsh chemical environment in the exhaust gas of diesel vehicles. This paper will present further durability evaluation results of the new Si bonded SiC particulate filters which have been collected in engine bench tests and vehicle durability runs. The Si-SiC filters passed both 100 and 200 regeneration cycles under severe ageing conditions and without any problems. The used filters were subjected to a variety of analytical tests. The back pressure and ash distribution were determined. The filter material was also analysed.
Technical Paper

Application of Converter Efficiency Simulation Tool for Substrate Design

2004-03-08
2004-01-1487
As emissions regulations are becoming more stringent, various efforts to improve emission performance have been carried out in different areas including the honeycomb structure of catalytic converters. This report describes the development of a simulation tool to predict emission performance and simulation results for different cell structures. The simulation model was developed based on global kinetic chemical reaction model [1]. Having tuned the reaction parameters through a light-off test and estimated oxygen storage capacity through an oxygen storage test, we ultimately tuned the model in a vehicle test (with Bags 1 and 2, FTP 75). As a result, the simulated cumulative tailpipe emissions are within ±25 percent of the test results. Parameter analyses indicate that the amount of emissions decreased as the density of cells increased and that the amount of emissions also decreased the thinner the wall thicknesses were.
Technical Paper

Study on Reliability of Wall-Flow Type Diesel Particulate Filter

2004-03-08
2004-01-0959
In this paper a method of DPF(Diesel Particulate Filter) lifetime estimation against the thermal stress is presented. In the method, experimentally measured material fatigue property and DPF temperature distributions under various conditions including regeneration mode were used to perform FEM stress analyses and the estimation of DPF lifetime and allowable stresses. From the viewpoint of the system design, to prevent DPF damages such as cracks created through thermal stress or melting, controlling the amount of PM accumulation is important. In this study, the pressure difference behavior under each of PM accumulation mode and regeneration mode was investigated experimentally. The experimental results showed different pressure drop behaviors in accumulation and regeneration. DPFs were observed in detail after PM accumulation and during regeneration to discuss mechanisms of the pressure difference behavior.
Technical Paper

Effect of Cell Shape on Mass Transfer and Pressure Loss

2003-03-03
2003-01-0659
To meet stringent emissions regulations, high conversion efficiency is required. This calls for advanced catalyst substrates with thinner walls and higher cell density. Higher cell density is needed because it brings higher mass transfer from the gas to the substrate wall. Basically, the increase in total surface area (TSA) causes higher mass transfer. However, not only the TSA, but the cell shape also has a great effect on mass transfer. There are two main kinds of substrates. One is the extruded ceramic substrate and the other is the metal foil type substrate. These have different cell shapes due to different manufacturing processes. For the extruded ceramic substrate, it is possible to fabricate various cell shapes such as triangle, hexagon, etc. as well as the square shape. The difference in the cell shape changes not only the mass transfer rate, but also causes pressure loss change. This is an important item to be considered in the substrate design.
Technical Paper

Influence of Cell Shape Between Square and Hexagonal Cells

2003-03-03
2003-01-0661
Developing ultra thin wall ceramic substrates is necessary to meet stricter emissions regulations, in part because substrate cell walls need to be thinner in order to improve warm-up and light-off characteristics and lower exhaust system backpressure. However, the thinner the cell wall becomes, the poorer the mechanical and thermal characteristics of the substrate. Furthermore, the conditions under which the ultra thin wall substrates are used are becoming more severe. Therefore both the mechanical and thermal characteristics are becoming important parameters in the design of advanced converter systems. Whereas square cells are used world-wide in conjunction with oxidation and/or three-way catalysts, hexagonal cells, with features promoting a homogeneous catalyst coating layer, have found limited use as a NOx absorber due to its enhanced sulfur desorption capability.
Technical Paper

The Effect of SiC Properties on the Performance of Catalyzed Diesel Particulate Filter(DPF)

2003-03-03
2003-01-0383
The DPF(Diesel Particulate Filter) has been established as a key technology in reducing diesel PM emission. Also Catalyzed-DPF Systems are viewed as the next generation DPF System in the automotive sector, replacing the current Fuel Additive System. The performance requirements of the DPF-equipped vehicle are good fuel economy, good driving performance, high PM regeneration performance of accumulated soot and high durability. In this paper the effect of Catalyzed-DPF characteristics, such as porosity, pore size, cell structure and catalyst loading have been defined on pressure drop, filtration efficiency, regeneration efficiency and regeneration behavior.
Technical Paper

Development of the NOx Adsorber Catalyst for Use with High-Temperature Condition

2001-03-05
2001-01-1298
NOx adsorber has already been used for the after-treatment system of series production vehicle installed with a lean burn or direct injection engine [1,2,3]. In order to improve NOx adsorbability at high temperatures, many researchers have recently been trying an addition of potassium (K) as well as other conventional NOx adsorbents. Potassium, however, reacts easily with the cordierite honeycomb substrate at high temperatures, and not only causes a loss in NOx adsorbability but also damages the substrate. Three new technologies have been proposed in consideration of the above circumstances. First, a new concept of K-capture is applied in washcoat design, mixed with zeolite, to improve thermal stability of K and to keep high NOx conversion efficiency, under high temperatures, of NOx adsorber catalyst. Second, another new technology, pre-coating silica over the boundary of a substrate and washcoat, is proposed to prevent the reaction between potassium and cordierite.
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