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Technical Paper

LOTUS: A Co-operation for Low Temperature Urea-Based Selective Catalytic Reduction of NOx

2004-03-08
2004-01-1294
The European research co-operation Lotus is presented. The main objectives of the project were i) to show the potential for a urea-based SCR system to comply with the EU standard of years 2005 and 2008 for heavy-duty Diesel engines for different driving conditions with optimal fuel consumption, ii) to reach 95 % conversion of NOx at steady state at full load on a Euro III engine, iii) to reach 75 % NOx reduction for exhaust temperatures between 200-300°C, and 85 % average NOx reduction between 200-500°C. The energy content of the consumed urea should not exceed 1.0 %, calculated as specific fuel consumption. These targets were met in May 2003 and the Lotus SCR system fulfilled the Euro V NOx legislative objectives for year 2008.
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

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

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.
Technical Paper

Turbocharging of Downsized Gasoline DI Engines with 2 and 3 Cylinders

2011-09-11
2011-24-0138
Turbocharged DISI engines with four cylinders have established in the market and provide a performance comparable to larger six-cylinder engines in the smaller compartment of a four-cylinder engine. In the Japanese market, also turbo gasoline engines with 500 - 660 cm₃ displacement have a long tradition in Kei-Cars. However, those engines show a lower specific performance as would be required for propelling typical small or compact vehicles in Europe. Recently, two-cylinder turbo engines have come to market, which are found attractive with respect to sound, package, and also enable low vehicle fuel consumption in NEDC test. The paper presents a turbocharger layout study on 2- and 3-cylinder engines. It discusses the influence of cylinder displacement volume on the sizing of turbines and compressors, and how specific flow phenomena in the turbine can be captured in the simulation model.
Technical Paper

A New Approach for Optimization of Mixture Formation on Gasoline DI Engines

2010-04-12
2010-01-0591
Advanced technologies such as direct injection DI, turbocharging and variable valve timing, have lead to a significant evolution of the gasoline engine with positive effects on driving pleasure, fuel consumption and emissions. Today's developments are primarily focused on the implementation of improved full load characteristics for driving performance and fuel consumption reduction with stoichiometric operation, following the downsizing approach in combination with turbocharging and high specific power. The requirements of a relatively small cylinder displacement with high specific power and a wide flexibility of DI injection specifications lead to competing development targets and additionally to a high number of degrees of freedom during optimization. In order to successfully approach an optimum solution, FEV has evolved an advanced development methodology, which is based on the combination of simulation, optical diagnostics and engine thermodynamics testing.
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

Diesel Engine Cold Start Noise Improvement

2005-05-16
2005-01-2490
The European as well as U.S. market share of modern Diesel engines has increased significantly in recent years, due to their excellent torque and performance behavior combined with low fuel consumption. The overall improved noise and vibration behavior of modern Diesel engines has also contributed to this trend. Despite overall improvements in Diesel engine noise and vibration, certain aspects of Diesel engines continue to present significant challenges. One such issue is the presence of Diesel knocking that is prevalent during cold start and warm-up conditions. This paper discusses a technique used to optimize the cold start noise behavior of modern Diesel engines. The methods used in this study are based on optimizing the engine calibration to improve the vehicle interior and exterior (engine) noise, even at low ambient temperatures.
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

Fuel Efficient Natural Gas Engine with Common-Rail Micro-Pilot Injection

2000-08-21
2000-01-3080
In the recent years, it has become obvious that one of the main fields of interest in alternate fuels is the public transportation sector. Natural Gas seems to be advantageous. It is available and environmentally friendly, even if the greenhouse effect of methane is considered. The operation range of vehicles running on CNG (Compressed Natural Gas) is poor due to the large pressure vessels, but in case of urban buses with low daily mileage this is acceptable. On the other hand, the use of an environmentally friendly fuel is favorable especially in urban areas. Although there are some advantages of Natural Gas, diesel buses dominate the market. The reason is the better part-load fuel efficiency of the Diesel principle which is superior to the Otto-cycle due to the absence of engine throttling. The efficiency levels of Spark-Ignition (SI) -type, Lean Burn Natural Gas engines are quite comparable to diesel engines during full load conditions.
Technical Paper

New CNG Concepts for Passenger Cars: High Torque Engines with Superior Fuel Consumption

2003-06-23
2003-01-2264
Since the CO2 emissions of passenger car traffic and their greenhouse potential are in the public interest, natural gas (CNG) is discussed as an attractive alternative fuel. The engine concepts that have been applied to date are mainly based upon common gasoline engine technology. In addition, in mono-fuel applications, it is made use of an increased compression ratio -thanks to the RON (Research Octane Number) potential of CNG-, which allows for thermodynamic benefits. This paper presents advanced engine concepts that make further use of the potentials linked to CNG. Above all, the improved knock tolerance, which can be particularly utilized in turbocharged engine concepts. For bi-fuel (CNG/gasoline) power trains, the realization of variable compression ratio is of special interest. Moreover, lean burn technology is a perfect match for CNG engines. Fuel economy and emission level are evaluated basing on test bench and vehicle investigations.
Technical Paper

Thermodynamical and Mechanical Approach Towards a Variable Valve Train for the Controlled Auto Ignition Combustion Process

2005-04-11
2005-01-0762
Controlled Auto Ignition (CAI) as a promising future combustion process is a concept to strongly reduce fuel consumption as well as NOx emissions. The acceptance and the potential of this combustion process depends on the possible CAI operation range in the engine map and the fuel consumption benefit, as well as the complexity of the variable valve train which is necessary to realize the CAI combustion process. The thermodynamic investigations presented in this paper were done on an engine equipped with an electromechanical valve train (EMVT), featuring Port Fuel Injection (PFI) and direct Injection. They show that the electromechanical valve train is an excellent platform for developing the CAI process. Controlled Auto Ignition has been realized with port fuel injection in a speed range between 1000 and 4500 rpm and in a load range between approximately 1 and 6 bar BMEP (about 5 bar BMEP for pressure gradients lower than 3 bar/°CA) depending on engine speed.
Technical Paper

Downsizing of Diesel Engines: 3-Cylinder / 4-Cylinder

2000-03-06
2000-01-0990
Due to the future application of combustion engines in small and hybrid vehicles, the demand for high efficiency with low mass and compact engine design is of prime importance. The diesel engine, with its outstanding thermal efficiency, is a well suited candidate for such applications. In order to realize these targets, future diesel engines will need to have increasingly higher specific output combined with increased power to weight ratios. This is therefore driving the need for new designs of 3 and/or 4 cylinder, small bore engines of low displacement, sub 1.5l. Recent work on combustion development, has shown that combustion systems, ports, valves and injector sizes are available for bore sizes down to 65 mm.
Technical Paper

Low fuel consumption and low emissions~Electromechanical valve train in vehicle operation

2000-06-12
2000-05-0018
The electromechanical valve train (EMV) technology allows for a reduction in fuel consumption while operating under a stoichiometric air-fuel ratio and preserves the ability to use conventional exhaust gas aftertreatment technology with a 3-way catalyst. Compared with an engine with a camshaft-driven valve train, the variable valve timing concept makes possible an additional optimization of cold start, warm-up and transient operation. In contrast with the conventionally throttled engine, optimized control of load and in-cylinder gas movement can be used for each individual cylinder and engine cycle. A load control strategy using a "Late Intake Valve Open" (LIO) provides a reduction in start-up HC emissions of approximately 60%. Due to reduced wall-wetting, the LIO control strategy improves the transition from start to idle.
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

Vehicle Study on the Impact of Diesel Fuel Sulfur Content on the Performance of DeNOX Catalysts and the Influence of DeNOX Catalysts on Particle Size and Number

2000-06-19
2000-01-1877
A vehicle investigation programme was initiated to evaluate the influence of diesel fuel sulfur content on the performance of a DeNOx catalyst for NOx control. The programme was conducted with a passive DeNOx catalyst, selected for its good NOx reduction performance and two specially prepared fuels with different sulfur contents. Regulated emissions were measured and analysed during the course of the programme. The NOx conversion efficiency of the DeNOx catalyst increased from 14 to 26% over the new European test cycle when the sulfur content of the diesel fuel was reduced from 49 to 6 wt.-ppm. In addition the number and size of particles produced using 6 wt.-ppm sulfur fuel were measured by two different techniques: mobility diameter by SMPS and aerodynamic diameter by impactor. The influence of the assumed density of the particulate on the apparent diameters measured by the two techniques is discussed.
Technical Paper

Low Emission and Fuel Consumption Natural Gas Engines with High Power Density for Stationary and Heavy-Duty Application

1999-08-17
1999-01-2896
Today, natural gas engines for stationary and vehicular applications are not only faced with stringent emission legislation, but also with increasing requirements for power density and efficient fuel consumption. For vehicular use, downsizing is an advantageous approach to lowering on-road fuel consumption and making gas engines more competitive with their diesel counterparts. In SI-engines, the power density at a given compression ratio is limited by knocking, or NOx emissions. A decrease in compression ratio, lowering both NOx emissions and the risk of knocking combustion, increases fuel consumption. An increase in air-fuel-ratio, required to avoid knocking at higher thermal loading, increases boost pressure, HC and CO emissions, and mechanical loading and causes the danger of misfiring. As a result, the performance of the latest production gas engines for vehicles remains at a BMEP of 18…20 bar with a NOx emission level of 2…5 g/kWh.
Technical Paper

Variable Compression Ratio - A Design Solution for Fuel Economy Concepts

2002-03-04
2002-01-1103
The challenge to reduce fuel consumption in S.I. engines is leading to the application of new series production technologies: including direct injection and, recently, the variable valve train, both aiming at unthrottled engine operation. In addition to these technologies, turbo- or mechanical supercharging is of increasing interest because, in principle, it offers a significant potential for improved fuel economy. However, a fixed compression ratio normally leads to a compromise, in that the charged engine is more of a performance enhancement than an improver of fuel economy. Fuel efficient downsizing concepts can be realized through the application of variable compression ratio. In this paper, a variable compression ratio design solution featuring eccentric movement of the crankshaft is described. Special attention is given to the integration of this solution into the base engine.
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

Benefits of the Electromechanical Valve Train in Vehicle Operation

2000-03-06
2000-01-1223
One of the most promising methods to reduce fuel consumption is to use unthrottled engine operation, where load control occurs by means of variable valve timing with an electromechanical valve train (EMV) system. This method allows for a reduction in fuel consumption while operating under a stoichiometric air-fuel-ratio and preserves the ability to use conventional exhaust gas aftertreatment technology with a 3-way-catalyst. Compared with an engine with a camshaft-driven valve train, the variable valve timing concept makes possible an additional optimization of cold start, warm-up and transient operation. In contrast with the conventionally throttled engine, optimized control of load and in-cylinder gas movement is made possible from the start of the first cycle. A load control strategy using a “Late Intake Valve Open” (LIO) provides a reduction in start-up HC emissions of approximately 60%.
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