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Technical Paper

On-Vehicle Fuel Cut Testing for Gasoline Particulate Filter Applications

2019-04-02
2019-01-0968
With the introduction of a stringent particulate number (PN) limit and real driving emission (RDE) requirements, gasoline particulate filters (GPF) are widely adopted for gasoline engines in Europe and China. The filter collects soot and ash. Like in diesel applications, the collected soot will continuously burn under favorable exhaust conditions. However, at extreme conditions, there could be large amounts of soot build-up, which may induce a highly exothermal event, potentially damaging the filter. Thus, it is important to understand what drives the over-heating in application, and develop counter measures. In this study, an on-vehicle fuel cut (FC) testing procedure was developed. The testing was conducted on two vehicles, one gasoline direct injection (GDI) vehicle and one multiple port injection (MPI) vehicle, with different exhaust systems designs (a close coupled GPF and an under floor GPF) and catalyst coating levels (bare and heavily coated GPFs).
Technical Paper

A Study into the Impact of Engine Oil on Gasoline Particulate Filter Performance through a Real-World Fleet Test

2019-04-02
2019-01-0299
Increasingly stringent vehicle emissions legislation is being introduced throughout the world, regulating the allowed levels of particulate matter emitted from vehicle tailpipes. The regulation may prove challenging for gasoline vehicles equipped with modern gasoline direct injection (GDI) technology, owing to their increased levels of particulate matter production. It is expected that gasoline particulate filters (GPFs) will soon be fitted to most vehicles sold in China and Europe, allowing for carbonaceous particulate matter to be effectively captured. However, GPFs will also capture and accumulate non-combustible inorganic ash within them, mainly derived from engine oil. Studies exist to demonstrate the impact of such ash on GPF and vehicle performance, but these commonly make use of accelerated ash loading methods, which themselves introduce significant variation.
Technical Paper

Next Generation Cordierite Thin Wall DPF for Improved Pressure Drop and Lifetime Pressure Drop Solution

2016-04-05
2016-01-0940
Diesel particulate filters (DPF) have become a standard aftertreatment component for a majority of current on-road/non-road diesel engines used in the US and Europe. The upcoming Stage V emissions regulations in Europe will make DPFs a standard component for emissions reductions for non-road engines. The tightening in NOx emissions standard has resulted in the use of selective catalytic reduction (SCR) technology for NOx reduction and as a result the general trend in engine technology as of today is towards a higher engine-out NOx/PM ratio enabling passive regeneration of the DPF. The novel filter concept discussed in this paper is optimized for low pressure drop, high filtration efficiency, and low thermal mass for optimized regeneration and fast heat-up, therefore reducing CO2 implications for the DPF operation.
Journal Article

Vehicular Emissions in Review

2013-04-08
2013-01-0538
This review paper summarizes major developments in vehicular emissions regulations and technologies (light-duty, heavy-duty, gasoline, diesel) in 2012. First, the paper covers the key regulatory developments in the field, including finalized criteria pollutant tightening in California; and in Europe, the development of real-world driving emissions (RDE) standards. The US finalized LD (light-duty) greenhouse gas (GHG) regulation for 2017-25. The paper then gives a brief, high-level overview of key developments in LD and HD engine technology, covering both gasoline and diesel. Marked improvements in engine efficiency are summarized for gasoline and diesel engines to meet both the emerging NOx and GHG regulations. HD engines are just starting to demonstrate 50% brake thermal efficiency. NOx control technologies are then summarized, including SCR (selective catalytic reduction) with ammonia, and hydrocarbon-based approaches.
Technical Paper

Impacts of B20 Biodiesel on Cordierite Diesel Particulate Filter Performance

2009-11-02
2009-01-2736
Engine laboratory tests were conducted to assess the impact of B20 biodiesel on the performance of cordierite diesel particulate filters (DPFs). Test fuels included 20% soy based methyl ester blended into ultra low sulfur diesel fuel, and two ULSD on-road market fuels. B20 has a higher cetane number, boiling point and oxygen content than typical on-road diesel fuels. A comparative study was performed using a model year 2007 medium duty diesel truck engine. The aftertreatment system included a diesel oxidation catalyst (DOC) followed by a cordierite wall flow DPF. A laboratory-grade supplemental fuel doser was used in the exhaust stream for precise regeneration of the DPF. Tests revealed that the fuel dosing rate was higher and DOC fuel conversion efficiency was poorer for the B20 fuel during low exhaust temperature regenerations. The slip of B20 fuel past the DOC was shown to produce significantly higher exotherms in the DPF during regeneration.
Journal Article

Diesel Emission Control in Review

2009-04-20
2009-01-0121
This summary covers representative developments from 2008 in diesel regulations, engine technology, and NOx, particulate matter (PM), and hydrocarbon (HC) control. Europe is finalizing the Euro VI heavy-duty (HD) regulations for 2013 with the intent of technologically harmonizing with the US. A new particle number standard will be adopted. California is considering tightening the light-duty fleet average to US Tier 2 Bin 2 levels, and CO2 mandates are emerging in Europe for LD, and in the US for all vehicles. LD engine technology is focused on downsizing to deliver lower CO2 emissions, enabled by advances in boost and EGR (exhaust gas recirculation). Emerging concepts are shown for attaining Bin 2 emission levels. HD engines will make deNOx systems optional for even the tightest NOx standards, but deNOx systems enable much lower fuel consumption levels and will likely be used. NOx control is centered on SCR (selective catalytic reduction) for diverse applications.
Journal Article

Diesel Emission Control in Review

2008-04-14
2008-01-0069
This summary covers the developments from 2007 in diesel regulations, engine technology, and NOx and PM control. Regulatory developments are now focused on Europe, where heavy-duty regulations have been proposed for 2013. The regulations are similar in technology needs to US2010. Also, the European Commission proposed the first CO2 emission limits of 130 g/km, which are nearly at parity to the Japanese fuel economy standards. Engines are making very impressive progress, with clean combustion strategies in active development mainly for US light-duty application. Heavy-duty research engines are more focused on traditional approaches, and will provide numerous engine/aftertreatment options for hitting the tight US 2010 regulations. NOx control is centered on SCR (selective catalytic reduction) for diverse applications. Focus is on cold operation and system optimization. LNT (lean NOx traps) durability is quantified, and performance enhanced with a sulfur trap.
Journal Article

Regeneration Strategies for an Enhanced Thermal Management of Oxide Diesel Particulate Filters

2008-04-14
2008-01-0328
Diesel particulate filters are expected to be used on most passenger car applications designed to meet coming European emission standards, EU5 and EU6. Similar expectations hold for systems designed to meet US Tier 2 Bin 5 standards. Among the various products oxide filter materials, such as cordierite and aluminum titanate, are gaining growing interest due to their unique properties. Besides the intrinsic robustness of the filter products a well designed operating strategy is required for the successful use of filters. The operating strategy is comprised of two elements: the soot estimation and the regeneration strategy. In this paper the second element is discussed in detail by means of theoretical considerations as well as dedicated engine bench experiments. The impact the key operating variables, soot load, exhaust mass flow, oxygen content and temperature, have on the conditions inside the filter are discussed.
Journal Article

Impact of Ceramic Substrate Web Thickness on Emission Light-Off, Pressure Drop, and Strength

2008-04-14
2008-01-0808
The effect of web thickness on emission performance, pressure drop, and mechanical properties was investigated for a series of catalyzed ceramic monolith substrates having cell densities of 900, 600 and 400 cpsi. As expected, thinner webs provide better catalyst light off performance and lower pressure drop, but mechanical strength generally decreases as web thickness is reduced. Good correlations were found between emission performance and geometric parameters based on bare and coated parts. An improved method for estimating the effects of cell density and web thickness on bare substrate strength is described, and the effect of porosity on material strength is also examined. New mechanical strength correlations for ceramic honeycombs are presented. The availability of a range of ceramic product geometries provides options for gasoline exhaust emission design and optimization, especially where increased levels of performance are desired.
Journal Article

Oxide Based Particulate Filters for Light-Duty Diesel Applications - Impact of the Filter Length on the Regeneration and Pressure Drop Behavior

2008-04-14
2008-01-0485
Diesel particulate filters are becoming a standard for most light duty diesel applications designed for European EU5 and EU6 regulations. Oxide based filter materials are continuing to gain significant interest and have been in high volume serial application since 2005. Compared to carbide materials they show some unique properties. With respect to the design, the length of a filter is a key variable. Usually the prime design consideration is the desired filter volume. The diameter or frontal area is then usually defined by packaging constraints. Finally, the length is adapted. The paper provides experimental data on the impact this key design parameter has on the pressure drop and the thermal behavior under “worst case” regeneration conditions. A wide range of soot loads (from 4 g/dm3 to 9 g/dm3) as well as filter lengths from 6″ to 12″ is considered and evaluated under comparable experimental conditions.
Technical Paper

Two-Dimensional Transient Monolith Model for Selective Catalytic Reduction using Vanadia-based Catalyst

2008-01-09
2008-28-0022
In this paper, we report the modeling of the selective catalytic reduction (SCR) of NOx using ammonia on a commercial vanadia-titania based catalyst. The model combines a steady-state two-dimensional channel model with a transient two- or three-dimensional monolith model of the whole catalytic monolith converter. The reaction mechanism includes the standard and fast SCR reactions and also the high-temperature oxidation of ammonia to model the decrease in conversion observed at higher temperatures. We used in-house experimental data spanning a wide range of inlet compositions and temperatures to validate the model. The model was found to be in excellent quantitative agreement with the experimental data.
Technical Paper

Advanced Mounting System for Light Duty Diesel Filter

2007-04-16
2007-01-0471
This paper employs a systematic approach to packaging design and testing of a system and its components in order to determine the long term durability of light duty diesel filters. This effort has utilized a relatively new aluminum titanate filter technology as well as an advanced support mat technology engineered to provide superior holding force at lower temperatures while maintaining its high temperature performance. Together, these two new technologies form a system that addresses the unique operating conditions of diesel engines. Key physical properties of both the filter and the mat are demonstrated through laboratory testing. The system behavior is characterized by various laboratory techniques and validation procedures.
Technical Paper

Diesel Emission Control in Review

2007-04-16
2007-01-0233
This summary covers the developments from 2006 in diesel regulations, engine combustion, and NOx and PM remediation. Regulatory developments are now focused on Europe, where light-duty Euro 5 and 6 regulations have been proposed for 2009 and 2014, respectively. The regulations are lass stringent than those in the US, but options exist for adopting European vehicles for the US market. Europe is just beginning to look at heavy-duty regulations for 2012 and beyond. Engines are making very impressive progress, with clean combustion strategies in active development mainly for US light-duty application. Heavy-duty research engines are more focused on traditional approaches, and will provide numerous engine/aftertreatment options for hitting the tight US 2010 regulations. NOx control is focusing on SCR (selective catalytic reduction) for diverse applications. Focus is on cold operation, durability, secondary emissions, and system optimization.
Technical Paper

Performance Evaluations of Aluminum Titanate Diesel Particulate Filters

2007-04-16
2007-01-0656
Over the past decade, regulations for mobile source emissions have become more stringent thus, requiring advances in emissions systems to comply with the new standards. For the popular diesel powered passenger cars particularly in Europe, diesel particulate filters (DPFs) have been integrated to control particulate matter (PM) emissions. Corning Incorporated has developed a new proprietary aluminum titanate-based material for filter use in passenger car diesel applications. Aluminum titanate (hereafter referred to as AT) filters were launched commercially in the fall of 2005 and have been equipped on more than several hundred thousand European passenger vehicles. Due to their outstanding durability, filtration efficiency and pressure drop attributes, AT filters are an excellent fit for demanding applications in passenger cars. Extensive testing was conducted on engine to evaluate the survivability and long-term thermo-mechanical durability of AT filters.
Technical Paper

Three-Way-Catalyst Modeling - A Comparison of 1D and 2D Simulations

2007-04-16
2007-01-1071
In this paper we present a comparison of two different approaches to model three-way catalyst. First, a numerical sample case simulating light-off is used to compare the 1D and the 2D models. The advantages of each code are discussed with respect to required input data, detail level of the output, comparability, and computation time. Thus, the 2D model reveals significant radial temperature gradients inside the monolith during light-off. In a second step, the 2D model is compared with experimental data. One set of data consists of an air/fuel ratio varying sweep at isothermal conditions. Another set was gained by emission measurements during a real driving MVEG tests with varying substrate cell density & inlet conditions. From these experiments the applicability of the model to numerical parameter studies is discussed.
Technical Paper

Driving Down On-Highway Particulate Emissions

2006-04-03
2006-01-0916
It has been reported that particulate emissions from diesel vehicles could be associated with damaging human health, global warming and a reduction in air quality. These particles cover a very large size range, typically 3 to 10 000 nm. Filters in the vehicle exhaust systems can substantially reduce particulate emissions but until very recently it was not possible to directly characterise actual on-road emissions from a vehicle. This paper presents the first study of the effect of filter systems on the particulate emissions of a heavy-duty diesel vehicle during real-world driving. The presence of sulfur in the fuel and in the engine lubricant can lead to significant emissions of sulfate particles < 30 nm in size (nanoparticles).
Technical Paper

Diesel Emission Control in Review

2006-04-03
2006-01-0030
The paper summarizes the key developments in diesel emission control, generally for 2005. Regulatory targets for the next 10 years and projected advancements in engine technology are used to estimate future emission control needs. Recent NOx control developments on selective catalytic reduction (SCR), lean NOx traps (LNT) and lean NOx catalysts (LNC) are then summarized. Likewise, the paper covers important recent developments on diesel particulate filters (DPFs), summarizing regeneration strategies, new filter and catalyst materials, ash management, and PM measurement. Recent developments in diesel oxidation catalysts are also briefly summarized. Finally, the paper discusses examples of how it is all pulled together to meet the tightest future regulations.
Technical Paper

Aluminum Titanate Compositions for Diesel Particulate Filters

2005-04-11
2005-01-0583
Compositions in the mixed strontium/calcium feldspar ([Sr/Ca]O·Al2O3·2SiO2) - aluminum titanate (Al2O3·TiO2) system have been investigated as alternative materials for the diesel particulate filter (DPF) application. A key attribute of these compositions is their low coefficient of thermal expansion (CTE). Samples have been prepared with porosities of >50% having average pore sizes of between 12 and 16μm. The superior thermal shock resistance, increased resistance to ash attack, and high volumetric heat capacity of these materials, coupled with monolithic fabrication, provide certain advantages over currently available silicon carbide products. In addition, based on testing done so far aluminum titanate-based filters have demonstrated chemical durability and comparable pressure drop (both bare and catalyzed) to current, commercially available, silicon carbide products.
Technical Paper

Effect of Thermal Mass and Aging on CO-NOx Crossover and Light Off Behavior

2005-04-11
2005-01-1106
The tightening of emissions regulations has required changes in many areas of vehicle systems, including calibration strategies, catalytic converter strategies and exhaust configurations. Engine calibration strategies can be engineered to complement the performance parameters of the converter. Knowledge of the precise window of converter performance for different substrates can therefore provide guidance in targeting engine calibration strategies as well as selecting compatible converter systems within calibration constraints. In a previous paper [5], we explored the effect of thermal mass on emissions performance in the context of the FTP. This paper expands on the previous work and explores the effect of the aging cycle and thermal mass differences on CO-NOx crossover and light-off profiles. This analysis provides a tool to assist in design by defining a window of performance in the converter to be used in matching to a window of operation in the calibration.
Technical Paper

Evaluation of a Stronger Ultra Thin Wall Corning Substrate for Improved Performance

2005-04-11
2005-01-1109
Current trends in automotive emissions control have tended towards reduced mass substrates for improved light-off performance coupled with a reduction in PGM levels. This trend has led to increasingly thinner walls in the substrates and increased open frontal areas, with a potential of reducing the overall mechanical strength of the substrate relative to the thicker walled lower cell density supports. This change in demand driven technology has also led to developments, at times costly, in the processing of the catalytic converter system. Changes in mat materials, handling technology and coating variables are only a few sources of overall increased system costs. Corning has introduced the Celcor® XS™ product to the market which significantly increases the strength of thin and ultra thin walled substrates.
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