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When comparing automotive and large-bore diesel engines, the latter usually show lower specific fuel consumption values, while automotive engines are subject to much stricter emission standards. Within an FVV (Research Association for Combustion Engines) project these differences were identified, quantified and assigned to individual design and operation parameters. The approach was split in three different phases: 1 Comparison of different-sized diesel engines 2 Correlation of differences in fuel consumption to design and operating parameters 3 Further investigations under automotive boundary conditions The comparison in the first phase was made on the basis of operating data and energy balances as well as the separation of losses based on the thermodynamic analysis. To also determine the quantitative effects of each design and operating parameter, a 1D process calculation model of the passenger car engine was transformed gradually to a large-bore engine in the second phase.

Small natural gas cogeneration engines usually operate with lean mixture and late combustion phasing to comply with NOx emission standards, leading to significant losses in engine efficiency. Owing to water evaporation heat and high specific heat capacity of the water vapor, leads the water injection to cooling the combustion chamber charge, which enables earlier combustion phasing, higher compression ratio and thus higher engine efficiency. Therefore, water injection enables mitigating the tradeoff between NOx emissions and engine performance, without loss in engine efficiency. The intake port injection represents, because of the low required injection pressure and the simple injector integration, a cost-effective way to introduce water into the engine. Hence, the purpose of this work is to adapt the intake port water injection timing to the charge mixture flow conditions in the intake port.

Catalyst fouling by deposit formation on components in the exhaust aftertreatment system is critical since RDE limits must be obtained at any time. Besides, uncontrolled oxidation of carbonaceous deposits might damage the affected exhaust aftertreatment component. To comply with current and future emission standards, diesel engines are usually operated with high EGR rates leading to increased soot and hydrocarbon emissions, which increases the likeliness of the formation of carbonaceous deposits on EAT components. With this background, a research project investigating the influencing parameters and mechanisms of deposit formation on DOCs was carried out. In a follow-up project, the results will be used in order to compare different deposit removal strategies. Within the scope of the presented project, a reference driving cycle was developed in order to create deposits within a short time.

The response to increasingly stringent light duty diesel emission regulation is a nearly unanimous increase in heavy Exhaust Gas Recirculation (EGR) application to reduce feedgas NOx emissions. Little attention has been paid to the fact that heavy EGR usage is likely to push the engine operating conditions towards less efficient or even unstable regions of conventional centrifugal compressor operating maps. Moreover, the low oxygen content at part load operation also poses transient response challenges. Therefore, improving turbocharger efficiency at part load and extending the stable operating range is becoming critical for viable future low emission diesel engines. In this study of a turbocharger compression system, encompassing the airflow geometry from compressor impeller inlet to volute exit, a dual volute compressor concept was introduced, and Computational Fluid Dynamics (CFD) was used to investigate its effects on the overall expected performance level and range.

The reduction of emissions and fuel consumption represents a central aim of today's vehicle engineering, at the same time the customers' demands for comfort rise. In the context of increased relevance of emerging markets, differences in customer behaviour, market specific emission regulations and the variety of environmental impacts in different operational areas, the advantages of market and customer profile oriented vehicle development strategies become clearer. In this paper a holistic methodology for the definition of optimal, customer oriented requirements for new vehicle concepts will be explained. The so called 3D-method is suitable when defining basic properties, e.g. required capacity of electric energy storage or layout of power transmitting elements, dependent on user profiles, targeting e.g. emission reduction, lightweight design and range optimization of electric vehicles. Furthermore, it is used for the definition of durability requirements.