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Technical Paper

Vehicle Mass Lightening by Design of Light-weight Structured Substrates for Catalytic Converters

The clear objective of future powertrain development is strongly characterized by lowest emission impact and minimum overall system cost penalty to the customer. In the past decades emission impact has been primarily related to both optimization of combustion process and exhaust after-treatment system efficiency. Nowadays, weight reduction is one of the main objectives for vehicular applications, considering the related improvements both in fuel consumption (i.e. CO2 production) and engine-out emissions. The state of the art of catalytic converter systems for automotive ZEV-oriented applications has yet to be introduces into mass production. This paper investigates the successful application o metallic turbulent structures for catalytic converters along with innovative packaging considerations, such as structured outer mantle, which lead to significant weight reductions, exhaust backpressure minimization and improved overall emission conversion efficiency.
Technical Paper

Turbulent Flow Metal Substrates: A Way to Address Cold Start CO Emissions and to Optimize Catalyst Loading

Modern Diesel Engines equipped with Common-Rail Direct Injection and EGR are characterized by an increasingly high combustion efficiency. Consequently the exhaust gas temperature, especially during a cold start, is significantly reduced compared to typical values measured in previous engine generations. This leads to a potential problem with CO emission limit compliance. The present paper deals with an experimental investigation of turbulent-flow metal substrates, carried out on a vehicle roller bench using a production 1.3 Liter diesel engine equipped passenger car. The tested metal supported catalysts proved to yield extremely high conversion rates both during cold start and in warm operation phase. The improved mass transfer efficiency of the advanced metal substrates is related on one hand to the optimized coating technology and, on the other hand, to the enhanced flow performance in the single converter channels which is caused by structured metal foils.
Technical Paper

Pre-Turbocharger-Catalyst - Catalytic Performances on an Euro V Type Diesel Engine and Robust Design Development

Future emission legislation and new diesel engine technology tighten the requirements for modern diesel vehicle exhaust after-treatment systems. In particular, the oxidation catalyst system requires more efficiency to treat increasing raw emissions of HC and CO at low exhaust gas temperatures resulting from advanced combustion processes. This represents a big challenge for all developers today where the cost of raw materials continues to rise. Splitting the oxidation catalyst volume into two parts and mounting a very small part in front of a turbocharger on Euro III or Euro IV Diesel engines has been proved very efficient: Light off and maximum pollutant conversion rates were improved. New results gained with Pre Turbocharger Catalyst (PTC) on a Euro V type diesel engine are confirming previous observations. The complete after-treatment system of today's vehicles should be designed and developed for the whole life of the vehicle.
Technical Paper

Particle Number Emissions: An Analysis by Varying Engine/Exhaust-System Design and Operating Parameters

An increasing concern has been growing in the last years toward health effects due to Particulate Matter (PM) emissions. This triggered the widespread diffusion of Diesel Particulate Filters (DPFs), which equip almost every Diesel car and truck on the market, allowing to get large reduction (in the order of 95% and more) in terms of PM mass. However, PM health effects are believed to be more related to particle number rather than to particle mass. This gave rise in Europe to new regulations for passenger cars on total particle number, that will be introduced from EURO6 on. Engine/Exhaust-System assembly is therefore under investigation, to better understand the effectiveness of aftertreatment components toward particle number reduction, especially by varying engine and exhaust-system design/operating conditions, and to compare particle number emissions to particle mass emissions.
Technical Paper

Optimisation Development of Advanced Exhaust Gas After-treatment Systems for Automotive Applications

Future emission legislation can be met through substantial improvement in the effectiveness of the exhaust gas after-treatment system, the engine and the engine management system. For the catalytic converter, differentiation is necessary between the cold start behavior and the effectiveness at operating temperature. To be catalytically effective, a converter must be heated by the exhaust gas up to its light-off temperature. The major influential parameter for the light-off still is the supply of heat from the exhaust gas. Modification of the cold start calibration of engine control such as spark retard or increased idle speed can increase the temperature level of the exhaust gas. One further possibility is represented by a reduction of the critical mass ahead of the catalyst (exhaust manifold and pipe). Nevertheless the best measure to obtain optimal cold start effectiveness still seems to be locating the converter close to the engine.
Technical Paper

Numerical Simulation of Engines Fuelled by Hydrogen and Natural Gas Mixtures

The use of hydrogen (H2) as a fuel for urban private and public transport may represent a major solution to reduce pollutant emissions and CO2 production in urban areas. Looking for short-term solutions, the introduction of moderate quantities of H2 (up to 30%) into Natural Gas (NG) SI engines may be a feasible solution to get a faster combustion process, and therefore less HC and CO2 emissions, and a slight NOx increase which may be potentially limited by the adoption of lean-burn engine control strategies. However, concurrent effects of volumetric efficiency reduction and maximum temperature in the combustion chamber require a careful optimization of operating conditions to fully exploit the H2 potential and to determine the most convenient H2/NG mixture ratio. In that context, 3D numerical tools may be useful to analyze the effect of H2 introduction on engine performance.
Technical Paper

Model Based Design Procedure of After Treatment Systems for Non-Road Diesel Engines

In 2011-2013, regulations will be tightened for non-road vehicles, via the application of Stage III-B standards in Europe. With state-of-the-art technology (high pressure common rail, cooled EGR), non-road diesel engines will require DPFs to control PM, as 90% reduction is requested with respect to STAGE III-A standards. Additional challenges may also foresee the obtainment of STAGE III-B standards with STAGE III-A engine technology, by means of retrofit systems for PM control. In that case, retrofit systems must furthermore guarantee simple control systems, and must be robust especially in terms of limited back pressure increase during normal operation. Moreover, retrofit systems must offer flexibility from the design point of view, in order to be correctly operated with several engines of same class, possibly characterized by totally different PM flow rates, temperature, NOx and O₂ availability.
Technical Paper

Metal Supported Particulate Matter-Cat, A Low Impact and Cost Effective Solution for a 1.3 Euro IV Diesel Engine

Modern Diesel Engines equipped with Common-Rail Direct Injection, EGR and optimized combustion technology have been proven to reduce dramatically engine raw emissions both in terms of Nox and Particulate Matter. As a matter of fact the recently introduced FIAT 1.3 JTD 4 Cylinder Engine achieves Euro 4 limits with aid of conventional 2-way oxidation catalyst. Nevertheless some special applications, such as platforms with relatively higher gross vehicle weight possibly yield to PM-related issues. The present paper deals with the development program carried out to design a cost effective aftertreatment solution in order to address particulate matter tailpipe emissions. The major constraint of this development program was the extremely challenging packaging conditions and the absolute demand to avoid any major impact on the system design. The flow-through metal supported PM Filter Catalyst has been extensively tested on the specific vehicle application with aid of roller bench setup.
Technical Paper

Innovative metal supported catalysts for EU V Diesel Engines

Future stringent emission levels for NOx and PM will lead to the introduction of innovative combustion processes for diesel engines, such as premixed combustion, with the results to enhance the engine out emission of HC and CO. Therefore very efficient oxidation catalyst will be needed to face this possible issue. This paper deals with the optimization of a EU IV exhaust system by means of innovative metal supported catalyst, as for example the Pre Turbo Catalyst and the Hybrid Catalyst in combination with dedicated catalyst coatings. Moreover a base study over the use of PM-Filter Catalyst has been made, to show the efficiency of such a device with EU IV engine calibration. The second part of the paper deals with the turbulent like structured foils substrates to have an even more efficient diesel oxidation catalyst with very high volumetric efficiency.
Technical Paper

Effects of Biodiesel Distillation Process of Waste Cooking Oil Blends on DPF Behavior

The use of biodiesel has been widely accepted as an effective solution to reduce greenhouse emissions. The high potential of biodiesel in terms of PM emission reduction may represent an additional motivation for its wide use. This potential is related to the oxygenated nature of biodiesel, as well as its lower PAH and S, which leads, in general, to lower PM emissions as well as equal or slightly higher NOx emissions. According to these observations a different behavior of the Aftertreatment System (AS), especially as far as control issues of the Diesel Particulate Filter are concerned is also expected. The competition with the food sector is currently under debate, thus, besides second generation biofuels (e.g. from algae), the transesterification of Waste Cooking Oil (WCO) is another option, however needing further insight.
Technical Paper

Diesel Engine Biofuelling: Effects of Ash on the Behavior of the Diesel Particulate Filter

The use of biodiesels is an effective way to limit greenhouse emissions and partly limit the dependence on fossil primary sources. Biodiesel fuels also show interesting features in terms of PM-NOx emissions trade-off that appears more favorable toward an optimized control of the Diesel Particulate Filter (DPF). In fact, the DPF, which is the assessed aftertreatment technology to reduce PM emissions below the limits, suffers from fuel consumption penalization or excessive exhaust system backpressure, as a function of the frequency of the regeneration process. On the other side, issues such as the impact of the higher ash content of biodiesel on the DPF performance have also to be better understood. In the given scenario, an experimental study on a DEUTZ 4L off-road Diesel engine coupled to a DOC-DPF (Diesel Oxidation Catalyst-Diesel Particulate Filter) system is proposed in this paper.
Technical Paper

Development of an Engine Management Strategy and a Cost Effective Catalyst System to Meet SULEV Emission Requirements Demonstrated on a V-6 Engine

The study presented in this paper focuses on measures to minimize exhaust gas emissions to meet SULEV targets on a V6 engine by using a cost efficient system configuration. The study consists of three parts. A) In the first stage, the influence of engine management both on raw emissions and catalyst light off performance was optimized. B) Afterwards, the predefined high cell density catalyst system was tested on an engine test bench. In this stage, thermal data and engine out emissions were used for modeling and prediction of light-off performance for further optimized catalyst concepts. C) In the final stage of the program, the emission performance of the test matrix, including high cell density as well as multifunctional single substrate systems, are studied during the FTP cycle. The presented results show the approach to achieve SULEV emission compliance with innovative engine control strategies in combination with a cost effective metallic catalyst design.
Technical Paper

Design Techniques to Improve the Performances of Metal Supported Flow-Through Particulate Traps: an Experimental and Numerical Approach

Soot filtration represents a major problem for the complete exploiting of Diesel engines characteristics in terms of global efficiency and CO2 emissions. Even though the engines development in the last years let the engine performances improve, exhaust gas after treatment is still required to respect the foreseen limits for soot and NOx emissions. A flow-through particle trap has been presented with a great potential in soot removal without major penalties in terms of exhaust back pressure. The device performance is strictly connected to channel geometry. This paper deals with that relation by means of an experimental-numerical approach.
Technical Paper

Cold Start Thermal Management with Electrically Heated Catalyst: A Way to Lower Fuel Consumption

Recent engine development has been mainly driven by increased specific volumetric power and especially by fuel consumption minimization. On the other hand the stringent emission limits require a very fast cold start that can be reached only using tailored catalyst heating strategy. This kind of thermal management is widely used by engine manufactures although it leads to increased fuel consumption. This fuel penalty is usually higher for high power output engines that have a very low load during emission certification cycle leading to very low exhaust gas temperature and, consequently, the need of additional energy to increase the exhaust gas temperature is high. An alternative way to reach a fast light off minimizing fuel consumption increase is the use of an Electrical Heated Catalyst (EHC) that uses mechanical energy from the engine to generate the electrical energy to heat up the catalyst.
Technical Paper

Cell Shape Influence on Mass Transfer and Backpressure Losses in an Automotive Catalytic Converter

The development of catalytic converter systems for automotive applications is, to a great extent, related to monolith catalyst support materials and design. In this paper improvements of converter channels fluid-dynamics aiming to enhance pollutant conversion in all the engine operating conditions are investigated with respect to the role of channel cross-section shape on mass and heat transfer processes. The performances of different channel sections, characteristic of ceramic and metallic monoliths, have been compared by two strategies (respectively equal cell density and equal hydraulic diameter). The results have been examined in terms of mass conversion efficiency, thermal behavior and single channel backpressure for coated and non coated single channels. 3D numerical simulations have been used as an analysis tool to give a detailed insight of in-channel phenomena. Classical shapes have been analyzed and their relative performances are reported.
Technical Paper

Backpressure Optimized Metal Supported Close Coupled PE Catalyst - First Application on a Maserati Powertrain

Future stringent emission limits both in the European Community and USA require continuously increased conversion efficiency of exhaust after-treatment systems. Besides the obvious targets of fastest light-off performance, overall conversion efficiency and durability, catalytic converters for maximum output engines require highly optimized flow properties as well, in order to create minimum exhaust backpressure for low fuel consumption. This work deals with the design, development and serial introduction of a close coupled main catalyst system using the innovative technology of Perforated Foils (PE). By means of PE-technology, channel-to-channel gas mixing within the metal substrate could be achieved leading to dramatically reduced backpressure values compared with the conventional design.
Technical Paper

Application of metal-supported catalysts for diesel engines

Nearly all real diesel engines operations are leading to low exhaust temperatures. Standard catalyst technique remains therefore for significant time below light-off. To improve the conversion behavior two approaches were made: placement of tailor-fitted catalysts as close as possible to the engine exhaust port before turbocharger and usage of close coupled catalysts with the so-called hybrid design. Both measures are providing visible progress in reducing diesel engine emissions. Tests were made with modern diesel engines both for passenger cars and heavy-duty vehicles.
Technical Paper

Application of New Diesel Aftertreatment Strategies on a Production 1.9 L Common-Rail Turbocharged Engine

1 An experimental study has been carried out on a production vehicle by means of roller-bench emission tests in order to optimize alternative aftertreatment systems. To this aim different comparisons between the production exhaust system and new strategies are discussed in the present paper with aid of both modal emission data and bag tailpipe figures. The present work shows the application of a alternative solution that complies with future emission legislation with regard both to HC, CO, NOx and PM without any major engine power output or fuel consumption penalty.
Technical Paper

An Alternative Way to Reduce Fuel Consumption During Cold Start: The Electrically Heated Catalyst

It is well known that the optimal management of cold start is crucial to fulfill present and future emission legislation. During past years the catalytic converter has left its original under floor position to get increasingly closer to the engine in order to exploit higher exhaust gas temperature. Simultaneously, the exhaust gas temperature is becoming significantly lower, both in gasoline engines due to the extensive use of turbo charging, and in diesel engines thanks to very high combustion efficiency and in some cases the use of two stage turbo charging. A well established way to reach the catalyst light-off temperature fast enough to fulfill emission limits consists of artificially increasing the exhaust gas temperature. This has the drawback of a higher fuel consumption which conflicts with the tight CO2 targets now required of the OEMs.
Technical Paper

A New Approach of Accelerated Life Testing for Metallic Catalytic Converters

The Environmental Protection Agency (EPA) and California Air Resources Board (CARB) requirements for high mileage durability of emission components make it necessary to ensure the mechanical robustness of metallic catalytic converters. In addition, the robustness of design features must be assessed in the early design development phase without resorting to vehicle fleet testing. By following established reliability methods, a new approach for time and cost efficient accelerated durability testing was developed, which can account for the combined effects of critical stressors of a metallic catalytic converter. This paper describes the methodology used to determine the critical stressors and their levels in actual operating conditions which were determined by analyzing a broad range of vehicle test information. This information was used to develop a temperature profile and a high vibration load profile for the new life test method.