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A chemical sub-model for realistic CFD simulations of Diesel engines is developed and demonstrated by application to some test cases. The model uses a newly developed progress variable approach to incorporate a realistic treatment of chemical reactions into the description of the reactive flow. The progress variable model is based on defining variables that represent the onset and temporal development of chemical reactions before and during self ignition, as well as the stage of the actual combustion. Fundamental aspects of the model, especially its physical motivation and finding a proper progress variable, are discussed, as well as issues of practical implementation. Sample calculations of Diesel-typical combustion scenarios are presented which are based on the progress-variable model, showing the capability of the model to realistically describe the ignition-and combustion phase.

The main objective of engine 3D CFD simulation is nowadays the support for combustion design development. New combustion concepts (e.g. Low Temperature Combustion, HCCI, multiple injection strategies …) could be analyzed and predicted through detailed thermodynamical computation. To achieve this aim many simulation tools are needed: each of them has to be capable to reproduce the sensitivities of combustion design parameters through physically based models. The adopted approach consists of the coupling of different models for 3D-nozzle flow, orifice-resolved spray formation in Eulerian coordinates and combustion. The advantages of the method will be proofed on an operative DI-diesel truck engine case, run with different nozzle geometries.

Over the next decades to come, fossil fuel powered Internal Combustion Engines (ICE) will still constitute the major powertrains for land transport. Therefore, their impact on the global and local pollution and on the use of natural resources should be minimized. To this end, an extensive fundamental and practical study was performed to evaluate the potential benefits of simultaneously co-optimizing the system fuel-and-engine using diesel as an example. It will be clearly shown that the still unused co-optimizing of the system fuel-and-engine (including advanced exhaust after-treatment) as a single entity is a must for enabling cleaner future road transport by cleaner fuels since there are large, still unexploited potentials for improvements in road fuels which will provide major reductions in pollutant emissions both in vehicles already in the field and even more so in future dedicated vehicles.

A Mercedes E320 CDI vehicle has been modified for more optimal operation on Gas-To-Liquids (GTL) diesel fuel, in order to demonstrate the extent of exhaust emission reductions which are enabled by the properties of this fuel. The engine hardware changes employed comprised the fitment of re-specified fuel injectors and the reduction of the compression ratio from 18:1 to 15:1, as well as a re-optimisation of the software calibration. The demonstration vehicle has achieved a NOx emission of less that 0.08 g/km in the NEDC test cycle, while all other regulated emissions still meet the Euro 4 limits, as well as those currently proposed for Euro 5. CO2 emissions and fuel consumption, were not degraded with the optimised engine. This was achieved whilst employing only cost-neutral engine modifications, and with the standard vehicle exhaust system (oxidation catalyst and diesel particulate filter) fitted.

External Exhaust Gas Recirculation, EGR, is a central issue in controlling emissions in up-to-date diesel engines. An empirical model has been developed that calculates the EGR ratio as a function of the engine speed, the engine load and special characteristics of the heat release rate. It was found that three combustion characteristics correlate well with the EGR ratio. These characteristics are the ignition delay, the premixed combustion ratio and the mixing-controlled combustion ratio. The calculation of these characteristics is based on parameter subsets, which were determined using an optimization routine. The model presented was developed based on these optimized characteristics.

To fulfill future emission standards for diesel engines, combined after-treatment systems consisting of different catalyst technologies and diesel particulate filters (DPF) are necessary. For designing and optimizing the resulting systems of considerable complexity, effective simulation models of different catalyst and DPF technologies have been developed and integrated into a common simulation environment called ExACT (Exhaust After-treatment Components Toolbox). This publication focuses on a model for the NOx storage and reduction catalyst as a part of that simulation environment. A heterogeneous, spatially one-dimensional (1D), physically and chemically based mathematical model of the catalytic monolith has been developed. A global reaction kinetic approach has been chosen to describe reaction conversions on the washcoat. Reaction kinetic parameters have been evaluated from a series of laboratory experiments.

A numerical model describing the ammonia based SCR process of NOX on zeolite catalysts is presented. The model is able to simulate coated and extruded monoliths. The development of the reaction kinetics is based on a study which compares the activity of zeolite and vanadium based catalysts. This study was conducted in a microreactor loaded with washcoat powder and with crushed coated monoliths. A model for the SCR reaction kinetics on zeolite catalysts is presented. After the parameterization of the reaction mechanism the reaction kinetics were coupled with models for heat and mass transport. The model is validated with laboratory data and engine test bench measurement data over washcoated monolith catalysts. A numerical simulation study is presented, aiming to reveal the differences between zeolite and vanadium based SCR catalysts.

The integration of CAD/CAM/CAE in product development is the key to realize concurrent engineering. Generally, different systems are employed in product development department. These different systems create a lot of troubles such as difficult communication, misunderstanding and so on. A new approach to integrate CAD/CAM/CAE in one system based on CATIA for the end-to-end process in cylinder head development is presented. Multi-Model Technology (MMT) is used to create consistent and associated CAD models for the end-to-end process in cylinder head development. The concept and method to create and organize multi- models are discussed. A typically four-layer structure of MMT for mechanical products is defined. The multi-level structure of the cylinder head models based on MMT is provided. The CAD models of cylinder head created based on MMT can be used as the consistent model.

This paper introduces the new 1.6L engine family, designed and developed by the Chrysler group of DaimlerChrysler Corporation in cooperation with BMW. An overview of the engine's design features is provided, with a detailed review of the performance development process with emphasis on airflow, combustion, thermal management and friction. This information is presented, to provide an understanding of how the engine simultaneously achieves outstanding levels of torque, power, fuel consumption, emissions and idle stability. The use of analytical tools such as Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) in the optimization of the engine is shown.

A progress variable approach for the 3D-CFD simulation of DI-Diesel combustion is introduced. Considering the Diesel-typical combustion phases of auto-ignition, premixed and diffusion combustion, for each phase, a limited number of characteristic progress variables is defined. By spatial-temporal balancing of these progress variables, the combustion process is described. Embarking on this concept, it is possible to simulate the reaction processes with detailed chemistry schemes. The combustion model is coupled with a mesh-independent Eulerian-spray model in combination with orifice resolving meshes. The comparison between experiment and simulation for various Diesel engines shows good agreement for pressure traces, heat releases and flame structures.

After-treatment systems (ATS) consisting of new catalyst technologies and particulate filters will be necessary to meet increasingly stringent global regulations limiting particulate matter (PM) and NOx emissions from heavy duty and light duty diesel vehicles. Fuels and lubes contain elements such as sulfur, phosphorus and ash-forming metals that can adversely impact the efficiency and durability of these systems. Investigations of the impact of lubricant formulation on the transfer of ash-forming elements to diesel particulate filters (DPF) and transfer of sulfur to NOx storage catalysts were conducted using passenger car diesel engine technology. It was observed that for ATS configurations with catalyst(s) upstream of the DPF, transfer of ash-forming elements to the DPF was significantly lower than expected on the basis of oil consumption and lube composition. Sulfur transfer strongly correlated with oil consumption and lubricant sulfur content.

To meet future emission levels the industry is trying to reduce tailpipe emissions by both, engine measures and the development of novel aftertreatment concepts. The present study focuses on a joint development of aftertreatment concepts for gasoline engines that are optimized in terms of the exhaust system design, the catalyst technology and the system costs. The best performing system contains a close-coupled catalyst double brick arrangement using a new high thermal stable catalyst technology with low precious metal loading. This system also shows an increased tolerance against catalyst poisoning by engine oil.

Coming along with the present movement towards the ultimately variable engine, the need for clear and simple models for complex engine systems is rapidly increasing. In this context Common-Rail-Systems cause a special kind of problem due to of the high amount of parameters which cannot be taken into consideration with simple map-based models. For this reason models with a higher amount of complexity are necessary to realize a representative behavior of the simulation. The high computational time of the simulation, which is caused by the increased complexity, makes it nearly impossible to implement this type of model in software in closed loop applications or simulations for control purposes. In this paper a method for decreasing the complexity and accelerating the computing time of automotive engine models is being evaluated which uses an optimized method for each stage of the diesel engine process.

This paper describes the results of a joint development program focussing on the introduction of the new generation of Pt/Rh-technology for current and future emission standards as a cost effective alternative to the in serial Pd/Rh based exhaust gas concepts. In the initial phase of the program combinations of Pd- and Pt-based three-way catalyst technologies were evaluated on vehicles equipped with a 8 cylinder engine. One goal in this portion of the study was to achieve technical equivalence between a viable Pd-based technology and the new Pt/Rh technology in the underfloor position at lower precious metal loading. A combination of a close-coupled Pd/Rh technology and the new Pt/Rh in the underfloor position was able to meet the emission targets at significant lower costs of the system after a catalyst aging that resembles more than 100.000 km of vehicle German highway driving.

High demands in fuel consumption, efficiency, and low emissions lead to complex control functions for current and future diesel engine management systems. Great effort is necessary for their optimal calibration. At the same time, and particularly for cost reasons, many variants exist on one individual type of diesel engine management system. Not only is it used for several base engines, but these engines are also used in different environments and for different tasks. For optimal deployment, their calibration status must also be optimized individually. Furthermore, the demand for shorter development cycles and enhanced quality lead to a catalogue of new requirements for the calibration process and the affiliated tool. A new calibration system was developed, which optimally reflects the new demands.

The influence of adsorption and desorption processes on the non-thermal plasma enhanced catalytic reduction of NOx on NaZSM5- and Al2O3-based lean-NOx catalysts (Pt-NH4ZSM5, Cu-NaZSM5, Fe-NaZSM5, Pt-Al2O3, Pd-Al2O3, CuO-Al2O3, Ag-Al2O3) was investigated by temperature programmed reaction experiments in the temperature range from 100 °C to 600 °C. Dodecane was used as a reducing agent. Strong HC adsorption- and desorption effects were observed on the zeolite catalysts, which were not influenced by plasma-pretreatment. Adsorption of NO2 and desorption of NO occurred on Al2O3-based catalysts. By plasma-pretreatment adsorption of NO2 was induced at low temperatures. NOx-reduction rates of the catalysts Cu-NaZSM5, Fe-NaZSM5, and the Ag-Al2O3 were increased substantially by plasma-pretreatment. Both plasma-induced and catalytic oxidation of HCs were limiting factors of the NOx-reduction obtained on these catalysts.

The current is an investigation of the effects of charge motion, namely tumble, on the burn characteristics of the new Chrysler Hemi SI engine. In order to reduce prototyping, several combustion system designs were evaluated; some of which were eliminated prior to design inception solely based on CFD simulations. The effects of piston top and number of spark plugs were studied throughout the conceptual stage with the AVL-FIRE CFD code. It has been concluded that large-scale, persistent and coherent tumbling flow structures are essential to charge motion augmentation at ignition only if such structures are decimated right before ignition. Piston top had a detrimental effect on tumbling charge motion as the piston approaches the TDC. When compared to single spark plug operation, dual spark plug reflected considerable improvement on burn characteristics and engine performance as a consequence. The CFD simulations demonstrated good correlation with early dynamometer data.

The launching of direct injection gasoline engines is currently one of the major challenges for the automotive industry in the European Union. Besides its potential for a notable reduction of fuel consumption, the engine with direct gasoline injection also offers increased power during stoichiometric and stratified operation. These advantages will most probably lead to a significant market potential of the direct injection concept in the near future. In order to meet the increasingly more stringent European emission levels (EURO IV), new strategies for the exhaust gas aftertreatment are required. The most promising technique developed in recent years, especially for NOx conversion in lean exhaust gases, is the so-called NOx storage catalyst.

In view of limited crude oil resources, alternative fuels for internal combustion engines are currently being intensively researched. Synthetic fuels from natural gas offer a promising interim option before the development of CO2-neutral fuels. Up to a certain degree, these fuels can be tailored to the demands of modern engines, thus allowing a concurrent optimization of both the engine and the fuel. This paper summarizes investigations of a Gas-To-Liquid (GTL) diesel fuel in a modern, post-EURO 4 compliant diesel engine. The focus of the investigations was on power output, emissions performance and fuel economy, as well as acoustic performance, in comparison to a commercial EU diesel fuel. The engine investigations were accompanied by injection laboratory studies in order to assist in the performance analyses.

In this article model-based controller design techniques are investigated for the transient operation of a common-rail diesel engine in order to optimize driveability and to reduce soot emissions. The computer-aided design has benefits in reducing controller calibration time. This paper presents a nonlinear control concept for the coordinated control of the exhaust gas recirculation (EGR) valve and the variable geometry turbocharger (VGT) in a common-rail diesel engine. The overall controller structure is set up to regulate the total cylinder air-charge with a desired fresh air-charge amount by means of controlling the intake manifold pressure and estimating the fresh air-charge inducted into the cylinders. During varying engine operating conditions the two control loops are coordinated by a compensation of the EGR valve action through the VGT controller.