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In the environmentally conscious world we live in, auto manufacturers are under extreme pressure to reduce tailpipe emissions from cars and trucks. The manufacturers have responded by creating clean-burning engines and exhaust treatments that mainly produce CO2 and water vapor along with trace emissions of pollutants such as CO, THC, NOx, and CH4. The trace emissions are regulated by law, and testing must be performed to show that they are below a certain level for the vehicle to be classified as road legal. Modern engine and pollution control technology has moved so quickly toward zero pollutant emissions that the testing technology is no longer able to accurately measure the trace levels of pollutants. Negative emission values are often measured for some pollutants, as shown by results from eight laboratories independently testing the same SULEV automobile.

The new inline six cylinder Twin-Turbo gasoline engine forms the pinnacle of BMW's wide range of straight-six power units, developing maximum output of 300hp and a peak torque of 300 lb-ft with a displacement of 3.0 litre. Using two turbochargers in combination with the new BMW High Precision Fuel Injection leads to a responsive build-up of torque and to an impressive development of power over a wide engine speed range. This paper gives a detailed overview of the turbocharger-and the injection system and describes the effect of both systems on power and torque, as well as on fuel consumption and emission. The big advantage of using two small turbochargers is their low moment of inertia, even the slightest movement of the accelerator pedal by the driver's foot serving to immediately build up superior pressure and power. This puts an end to the turbo “gap” previously typical of a turbocharged power unit.

The spray-guided BMW DI combustion system eliminates the most important disadvantages of the wall-and air-guided 1st generation DI combustion systems. With its central injector position, the spray-guided system provides a stratified mixture at the spark plug and reduces wall wetting significantly. The low spray penetration and high spray stability of the outward-opening piezo injector allow an extension of the stratified engine map to higher engine load and speed. The piezo drive permits an extremely fast opening of the injector needle, thus enabling multiple injections with very short delay times and high flexibility for the calibration strategy to supply a very efficient combustion with low unburnt hydrocarbon and carbon monoxide emissions. Compared to a conventional throttled SI engine, the spray-guided system shows a fuel consumption potential of about 20% in the NEDC.

BMW VALVETRONIC technology is able to maintain the most important measures to reduce emissions. The further optimized charge movement created by VALVETRONIC stabilizes the combustion in the catalyst heating mode with extremely retarded ignition timing. When the engine is warm the high residual gas tolerance ensures very low Engine-Out NOx emissions and at the same time a low level of hydrocarbons. The atomization of fuel droplets due to high flow velocity in the valve gap area leads to improved mixture formation and reduced wall wetting. Engine-Out HC emissions in a cold engine are therefore reduced. Combined, the emission measures achieve robust and efficient emission control. In combination with additional after-treatment like secondary air system and catalysts using high cell density VALVETRONIC engines form an excellent base for SULEV emission regulations without neglecting the typical BMW claim of efficient dynamics.

In the near future the effort on the development of exhaust gas treatment systems must be increased to meet the stringent emission requirements. If the relevant physical and chemical models are available, the numerical simulation is an important tool for the design of these systems. This work presents a CFD model that allows to cover the full range of applications in this area. After a detailed presentation of the theoretical background and the modeling strategies results for the simulation of a close-coupled catalyst are shown. The presented model is also applied to the oxidation of nitrogen oxides, to a diesel particle filter and a fuel-cell reformer catalyst.

In a consortium of European industrial partners and research institutes, a combination of industrial development and scientific research was organised. The objective was to improve the catalytic NOx conversion for lean burn cars and heavy-duty trucks, taking into account boundary conditions for the fuel consumption. The project lasted for three years. During this period parallel research was conducted in research areas ranging from basic research based on a theoretical approach to full scale emission system development. NOx storage catalysts became a central part of the project. Catalysts were evaluated with respect to resistance towards sulphur poisoning. It was concluded that very low sulphur fuel is a necessity for efficient use of NOx trap technology. Additionally, attempts were made to develop methods for reactivating poisoned catalysts. Methods for short distance mixing were developed for the addition of reducing agent.