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Technical Paper

Development of a Desulfurization Strategy for a NOx Adsorber Catalyst System

2001-03-05
2001-01-0510
The aggressive reduction of future diesel engine NOx emission limits forces the heavy- and light-duty diesel engine manufacturers to develop means to comply with stringent legislation. As a result, different exhaust emission control technologies applicable to NOx have been the subject of many investigations. One of these systems is the NOx adsorber catalyst, which has shown high NOx conversion rates during previous investigations with acceptable fuel consumption penalties. In addition, the NOx adsorber catalyst does not require a secondary on-board reductant. However, the NOx adsorber catalyst also represents the most sulfur sensitive emissions control device currently under investigation for advanced NOx control. To remove the sulfur introduced into the system through the diesel fuel and stored on the catalyst sites during operation, specific regeneration strategies and boundary conditions were investigated and developed.
Technical Paper

Analytical and Empirical Methods for Optimization of Cylinder Liner Bore Distortion

2001-03-05
2001-01-0569
Beside the traditional prediction of stresses and verification by mechanical testing the optimization of cylinder liner bore distortion is one of today's most important topics in crankcase structure development. Low bore distortion opens up potentials for optimizing the piston group. As the piston rings achieve better sealing characteristics in a low deformation cylinder liner, oil consumption and blow-by are reduced. For unchanged oil consumption and blow-by demands, engine friction and subsequently, fuel consumption could be reduced by decreasing the pre-tension of the piston rings. From the acoustical point of view an optimization of piston-slap noise is often based on an optimized bore distortion behavior. Apart from basics to the behavior of liner bore distortion the paper presents advanced analytical and empirical methods for detailed prediction, verification and optimization of bore distortion taking into account the effective engine operation conditions.
Technical Paper

Vehicle Application of a 4-Cylinder Tumble DISI Engine

2001-03-05
2001-01-0735
SI engines with gasoline direct injection are currently the focus of development for almost all car manufacturers. After the introduction of DISI engines, first to the Japanese market and after a short time delay also in Europe, a broad variety of technical solutions for efficient stratified concepts can be stated. The targets of the development activities in this field are defined by legislation and customer's demands. The potential reduction of fuel consumption with stratified operation has to be combined with a further improvement of the full load potential of the DISI engine. A substantial part of the development activities are the fulfillment of current and future emission standards. Therefore, in order to realize a highly efficient lean operation, new technologies and strategies in the field of exhaust gas aftertreatment and vehicle application are required.
Technical Paper

Development of a charge motion controlled combustion system for DI SI engines and its vehicle application to EU-4 emission regulations

2000-06-12
2000-05-0058
The development of new passenger car powertrains with gasoline direct- injection engines is facing new requirements which result from the need of different operational modes with stratified and homogeneous air-fuel mixture. Moreover, the exhaust aftertreatment system causes a discontinuous operation with lean-burn absorption periods followed by short rich spikes for catalyst regeneration. Recent work on combustion system development has shown, that gasoline direct injection can create significant fuel economy benefits. Charge motion controlled combustion systems have proven to be of advantage in terms of low raw emissions compared to wall-guided concepts. Based on an initial single-cylinder development phase, a multi-cylinder engine was realized with excellent fuel economy, low raw emissions and operational robustness. Finally, the new engine''s potential has been demonstrated in a mid-class vehicle.
Technical Paper

Exhaust Heat Recovery System for Modern Cars

2001-03-05
2001-01-1020
The fuel consumption and the emissions of modern passenger cars are highly affected by the fluid and material temperatures of the engine. Unfortunately, the high thermal efficiencies of Direct Injection (DI) Diesel and Spark Ignition (SI) engines cause in many driving situations low heat transfer to the engine components and especially to the oil and the coolant. In these conditions the normal operating temperatures are not achieved. Especially at low ambient temperatures and low engine loads the requirement of a comfortable cabin heating and a fast warm-up of engine oil and coolant cannot be satisfied simultaneously. To reach the required warm-up performance, an Exhaust Heat Recovery System (EHRS) will be demonstrated. Further design and optimization processes for modern cooling systems in fuel-efficient engines require numerical and experimental investigations of supplemental heater systems to meet all requirements under all circumstances.
Technical Paper

Glow-plug Ignition of Ethanol Fuels under Diesel Engine Relevant Thermodynamic Conditions

2011-04-12
2011-01-1391
The requirement of reducing worldwide CO₂ emissions and engine pollutants are demanding an increased use of bio-fuels. Ethanol with its established production technology can contribute to this goal. However, due to its resistive auto-ignition behavior the use of ethanol-based fuels is limited to the spark-ignited gasoline combustion process. For application to the compression-ignited diesel combustion process advanced ignition systems are required. In general, ethanol offers a significant potential to improve the soot emission behavior of the diesel engine due to its oxygen content and its enhanced evaporation behavior. In this contribution the ignition behavior of ethanol and mixtures with high ethanol content is investigated in combination with advanced ignition systems with ceramic glow-plugs under diesel engine relevant thermodynamic conditions in a high pressure and temperature vessel.
Technical Paper

Future Emission Concepts versus Fuel Quality Aspects - Challenges and Technical Concepts

2011-08-30
2011-01-2097
From current point of view future emission legislations for heavy-duty engines as well as industrial engines will require complex engine internal measures in combination with sophisticated aftertreatment systems as well as according control strategies to reach the emission targets. With EU VI, JP 09/NLT and US10 for heavy-duty engines as well as future Tier4 final or stage IV emission legislation for industrial applications, EGR + DPF + SCR probably will be combined for most applications and therefore quite similar technological approaches will be followed up in Europe as well as in the US and in Japan. Most “emerging markets” all over the world follow up the European, US or Japanese emission legislation with a certain time delay. Therefore similar technologies need to be introduced in these markets in the future. On the other hand specific market boundary conditions and requirements have to be considered for the development of tailored system concepts in these markets.
Technical Paper

Shape Optimization of a Single Cylinder Engine Crankshaft

2011-04-12
2011-01-1077
Due to increasing demand for environment friendly vehicles with better fuel economy and strict legislations on greenhouse gas emissions, lightweight design has become one of the most important issues concerning the automobile industry. Within the scope of this work lightweight design potentials that a conventional single cylinder engine crankshaft offers are researched through utilization of structural optimization techniques. The objective of the study is to reduce mass and moment of inertia of the crankshaft with the least possible effect on the stiffness and strength. For precise definition of boundary conditions and loading scenarios multi body simulations are integrated into the optimization process. The loading conditions are updated at the beginning of each optimization loop, in which a multi body simulation of the output structure from the previous optimization loop is carried out.
Technical Paper

The Impact of Different Biofuel Components in Diesel Blends on Engine Efficiency and Emission Performance

2010-10-25
2010-01-2119
Within the Cluster of Excellence “Tailor-Made Fuels from Biomass” at RWTH Aachen University, the Institute for Combustion Engines carried out an investigation program to explore the potential of future biofuel components in Diesel blends. In this paper, thermodynamic single cylinder engine results of today's and future biofuel components are presented with respect to their engine-out emissions and engine efficiency. The investigations were divided into two phases: In the first phase, investigations were performed with rapeseed oil methyl ester (B100) and an Ethanol-Gasoline blend (E85). In order to analyze the impact of different fuel blends, mixtures with 10 vol-% of B100 or E85 and 90 vol-% of standardized EN590 Diesel were investigated. Due to the low cetane number of E85, it cannot be used purely in a Diesel engine.
Technical Paper

Tailor-Made Fuels: The Potential of Oxygen Content in Fuels for Advanced Diesel Combustion Systems

2009-11-02
2009-01-2765
Fuels derived from biomass will most likely contain oxygen due to the high amount of hydrogen needed to remove oxygen in the production process. Today, alcohol fuels (e. g. ethanol) are well understood for spark ignition engines. The Institute for Combustion Engines at RWTH Aachen University carried out a fuel investigation program to explore the potential of alcohol fuels as candidates for future compression ignition engines to reduce engine-out emissions while maintaining engine efficiency and an acceptable noise level. The soot formation and oxidation process when using alcohol fuels in diesel engines is not yet sufficiently understood. Depending on the chain length, alcohol fuels vary in cetane number and boiling temperature. Decanol possesses a diesel-like cetane number and a boiling point in the range of the diesel boiling curve. Thus, decanol was selected as an alcohol representative to investigate the influence of the oxygen content of an alcohol on the combustion performance.
Technical Paper

Optimized Layout of Gasoline Engines for Hybrid Powertrains

2008-01-09
2008-28-0024
Due to the complex powertrain layout in hybrid vehicles, different configurations concerning internal combustion engine, electric motor and transmission can be combined - as is demonstrated by currently produced hybrid vehicles ([1], [2]). At the Institute for Combustion Engines (VKA) at RWTH Aachen University a combination of simulation, Design of Experiments (DoE) and numerical optimization methods was used to optimize the combustion engine, the powertrain configuration and the operation strategy in hybrid powertrains. A parametric description allows a variation of the main hybrid parameters. Parallel as well as power-split hybrid powertrain configurations were optimized with regard to minimum fuel consumption in the New European Driving Cycle (NEDC). Besides the definition of the optimum configuration for engine, powertrain and operation strategy this approach offers the possibility to predict the fuel consumption for any modifications of the hybrid powertrains.
Technical Paper

Diesel Combustion Control with Closed-Loop Control of the Injection Strategy

2008-04-14
2008-01-0651
Current and future emission legislations require a significant reduction of engine-out emissions for Diesel engines. For a further reduction of engine-out emissions, different measures are necessary such as: Especially an advanced emission and closed-loop combustion control has gained increased significance during the past years.
Technical Paper

Gas Exchange Optimization and the Impact on Emission Reduction for HSDI Diesel Engines

2009-04-20
2009-01-0653
The main tasks for all future powertrain developments are: regulated emissions, CO2-values, comfort, good drivability, high reliability and affordable costs. One widely discussed approach for fuel consumption improvement within passenger car applications, is to incorporate the downsizing effect. To attain constant engine performance an increase of boost pressure and/or rated speed is mandatory. In both cases, the mass flow rate through the intake and exhaust ports and valves will rise. In this context, the impact of the port layout on the system has to be reassessed. In this paper, the impact of the port layout on a modern diesel combustion system will be discussed and a promising concept shall be described in detail. The investigations shown include flow measurements, PIV measurements of intake flow, CFD simulations of the flow field during intake and results from the thermodynamic test bench. One of the important topics is to prove the impact of the flow quality on the combustion.
Technical Paper

Fuel Property Effects on Emissions and Performance of a Light-Duty Diesel Engine

2009-04-20
2009-01-0488
Increased demand for highly fuel efficient propulsion systems drives the engine development community to develop advanced technologies allowing improving the overall thermal efficiency while maintaining low emission levels. In addition to improving the thermal efficiencies of the internal combustion engine itself the developments of fuels that allow improved combustion as well as lower the emissions footprint has intensified recently. This paper will describe the effects of five different fuel types with significantly differing fuel properties on a state-of-the-art light-duty HSDI diesel engine. The fuels cetane number ranges between 26 and 76. These fuels feature significantly differing boiling characteristics as well as heating values. The fuel selection also contains one pure biodiesel (SME - Soy Methyl Ester). This study was conducted in part load and full load operating points using a state of the art HSDI diesel engine.
Technical Paper

Tailor-Made Fuels for Future Advanced Diesel Combustion Engines

2009-06-15
2009-01-1811
The finite nature and instability of fossil fuel supply has led to an increasing and enduring investigation demand of alternative and regenerative fuels. The Institute for Combustion Engines at the RWTH Aachen University carried out an investigation program to explore the potential of tailor made fuels to reduce engine-out emissions while maintaining engine efficiency and an acceptable noise level. To enable optimum engine performance a range of different hydrocarbons having different fuel properties like cetane number, boiling temperature and different molecular compositions have been investigated. Paraffines and naphthenes were selected in order to better understand the effects of molecular composition and chain length on emissions and performance of an engine that was already optimized for advanced combustion performance. The diesel single-cylinder research engine used in this study will be used to meet Euro 6 emissions limits and beyond.
Technical Paper

Impact of Fuel Properties on Advanced Combustion Performance in a Diesel Bench Engine and Demonstrator Vehicle

2010-04-12
2010-01-0334
Six diesel, kerosene, gasoline-like, and naphtha fuels have been tested in a single cylinder diesel engine and a demonstrator vehicle, both equipped with similar engine technology and optimized for advanced combustion performance. This study was completed in order to investigate the potential to reduce engine-out emissions while maintaining engine efficiency and noise levels through changes in both engine hardware and fuel properties. The fuels investigated in this study were selected in order to better understand the effects of ignition quality, volatility, and molecular composition on engine-out emissions and performance. The optimized bench engine used in this study included engine hardware enhancements that are likely to be used to meet Euro 6 emissions limits and beyond, in part by operating under advanced combustion conditions, at least under some speed and load conditions.
Technical Paper

Complex Air Path Management Systems and Necessary Controller Structures for Future High Dynamic Requirements

2009-05-13
2009-01-1616
The future worldwide emission regulations will request a drastic decrease of Diesel engine tailpipe emissions. Depending on the planned application and the real official regulations, a further strong decrease of engine out emissions is necessary, even though the utilized exhaust after-treatment systems are very powerful. To reduce NOx emissions internally, the external exhaust gas recirculation (EGR) is known as the most effective way. Due to the continuously increasing requirements regarding specific power, dynamic behavior and low emissions, future air path systems have to fulfill higher requirements and, consequently, become more and more complex, e.g. arrangements with a 2-stage turbo charging or 2-stage EGR system with different stages of cooling performance.
Technical Paper

Interpretation Tools and Concepts for the Heat Management in the Drive Train of the Future

2011-04-12
2011-01-0650
Thermal management describes measures that result in the improved engine or vehicle operation in terms of energetics and thermo mechanics. In this context the involvement of the entire power train becomes more important as the interaction between engine, transmission and temperature sensitive battery package (of hybrid vehicles or electric vehicles with range extender) or the utilization of exhaust gas thermal energy play a major role for future power train concepts. The aim of thermal management strategies is to reduce fuel consumption while simultaneously increasing the comfort under consideration of all temperature limits. In this case it is essential to actively control the heat flow, in order to attain the optimal temperature distribution in the power train components.
Technical Paper

Advanced Combustion for Low Emissions and High Efficiency Part 2: Impact of Fuel Properties on HCCI Combustion

2008-10-06
2008-01-2404
A broad range of diesel, kerosene, and gasoline-like fuels has been tested in a single-cylinder diesel engine optimized for advanced combustion performance. These fuels were selected in order to better understand the effects of ignition quality, volatility, and molecular composition on engine-out emissions, performance, and noise levels. Low-level biofuel blends, both biodiesel (FAME) and ethanol, were included in the fuel set in order to test for short-term advantages or disadvantages. The diesel engine optimized in Part 1 of this study included cumulative engine hardware enhancements that are likely to be used to meet Euro 6 emissions limits and beyond, in part by operating under conditions of Homogeneous Charge Compression Ignition (HCCI), at least over some portions of the speed and load map.
Technical Paper

Closed Loop Combustion Control - Enabler of Future Refined Engine Performance Regarding Power, Efficiency, Emissions & NVH under Stringent Governmental Regulations

2011-09-11
2011-24-0171
Both, the continuous strengthening of the exhaust emission legislation and the striving for a substantial reduction of the carbon dioxide output in the traffic sector depict substantial requirements for the global automotive industry and especially for the engine manufacturers. From the multiplicity of possible approaches and strategies for clear compliance with these demands, engine internal measures offer a large and, eventually more important, very economical potential. For example, the achievements in fuel injection technology are a measure which in the last years has contributed significantly to a notable reduction of the emissions of the modern DI Diesel engines at favorable fuel efficiency. Besides the application of modern fuel injection technology, the linked combustion control (Closed Loop Combustion Control) opens possibilities for a further optimization of the combustion process.
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