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A common rail injection system was applied to port-loop and uniflow scavenged two-stroke DI-Diesel engines. While the uniflow scavenged configuration was operated with a swirl level comparable to that of 4-stroke DI-Diesel engines, no swirl motion was realized with the port-loop scavenged arrangement. The results show that, in spite of disadvantages in the mixture formation process, the high mixture formation energy observed with the common rail injection makes a swirl-free Diesel combustion possible. However, at part load the combustion process and emission level with the port-loop scavenged engine is not satisfactory. At full load, disadvantages in the scavenging process are observed in addition to the poorer mixture formation with the loop scavenged two-stroke concept. Consequently, the expected specific power output of the port-loop scavenged arrangement is with 20 kW/l far lower than about 45 kW/l predicted for the uniflow scavenged engine.

In conjunction with throttle-free load control on a 4-valve, single-cylinder spark-ignition engine, the influencing variables of charge cycle, mixture formation and combustion process are presented both as computer calculations and on the basis of test results. The influences of the position of the maximum of the inlet valve stroke, the position of the inlet close, the shape of the valve stroke and the load motion in relation to the maximum power and minimum fuel consumption are investigated in full load by computer calculations and in partial load by engine tests.

For real working-process simulations it is essential to know the caloric properties of the working fluid, such as the specific enthalpy and the real gas constant. When using standard-fuels there are established models which describe the caloric variables as functions of temperature, air/fuel-ratio and pressure. In each case, these models were developed for a certain fuel composition and their application to alternative fuels is limited or not valid at all. Thus, an approach is discussed, which is valid for any user-defined fuel. This work presents the formulations for the caloric modelling of burnt gas and fuel vapor, respectively. An algorithm is introduced that provides a very fast calculation of the chemical equilibrium condition of burnt gas. The influence of the equilibrium coefficients and the fuel composition on the chemical equilibrium composition is discussed.

In this paper, a simulation approach is introduced which takes into account all relevant heat sources and sinks in the combustion engine and in the engine compartment. With this approach, it is possible to calculate the appearing power flow and enthalpy flow as well as the component temperatures. Therefore, the complex thermodynamic and friction processes in the engine are described as simple as possible; the complete system can still be described reliably within certain limits, and the effects of different thermal optimization measures can be shown. It is an essential point for the modeling that only two integral quantities are necessary (the high pressure efficiency and the high pressure wall heat loss) for the complete combustion model.

A quasidimensional combustion model for homogenous spark ignition combustion processes with variable valve timing is proposed which is able to compute a complete engine map in advance and can be calibrated rapidly. In the engine map there are not only load and speed that do change considerably, the residual gas mass does so as well. This paper exposes the models' potential and limits by both simulation and measurement on two different engines with port-injection. Methods for model adjustment as well as the implementation in the commercial one-dimensional flow simulation software “GT-Power” will be shown. Furthermore a knock control is introduced and resulting errors are discussed.

The principle strategy, the development emphasis, and the investigation parameters of a DI gasoline engine are discussed. Several different combustion systems are briefly described and one system where the spark plug is located near the fuel injector is investigated. In addition, the influence of different operating parameters are studied. Some reasons for the improvement in the efficiency of a DI gasoline engine are shown with the help of thermodynamic analysis and simulation calculations. These show that at a constant operating point (engine speed = 2000 rpm, bmep = 2 bar) there is a reduction of the fuel consumption of 23% at unthrottled conditions in comparison to the homogeneous stoichiometric operation. In particular, the reduction of the pumping and heat losses and the reduction of the exhaust gas energy are responsible for this fuel consumption reduction.

This paper focuses onto mixture formation issues of the Directstart of a gasoline direct injection engine. Regarding the starterless Directstart, i.e. an engine start through targeted injection and ignition timing without the help of an electrical starter, engine tests show that there exists a large room for improvements by attending the mixture formation of the first combustion. The conditions for the first combustion are very unusual: ambient pressure, nearly the same fuel, engine and charge temperature, no piston movement and only spray induced turbulence. Furthermore, engine tests show that the mixture formation changes with the engine temperature. This paper analyzes the mixture formation of the first combustion for different engine conditions by means of engine measurements and both optical measurements in a spray chamber and simulations performed by the fast response 3D-CFD-Tool QuickSim of IVK/FKFS.

In order to fulfill future emissions standards, there is a need for new exhaust-gas aftertreatment concepts, with NOx-emissions reduction in passenger car diesel engines being of particular importance. The NOx storage catalyst is one of the technologies currently under discussion with high NOx conversion potential, and which is under development at DaimlerChrysler for EURO IV standards. With this system, the nitrogen oxides contained in the diesel exhaust gas are stored under lean exhaust-gas conditions and are reduced in the catalyst through an enriched air-fuel ratio of the exhaust-gas and favorable thermal conditions. Hydrocarbons, carbon monoxide and hydrogen are used as reducing agents. DaimlerChrysler has analyzed the effect of sulphur contained in the fuel on the operation of various catalysts during laboratory and engine testing. The sulphur dioxide in the exhaust gas generates sulfates, which remain on the catalyst when nitrate compounds are regenerated briefly.