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This paper will review several different emission control systems for heavy duty diesel (HDD) applications aimed at future legislations. The focus will be on the (DOC+CSF+SCR+ASC) configuration. As of today, various SCR technologies are used on commercial vehicles around the globe. Moving beyond EuroVI/US10 emission levels, both fuel consumption savings and higher catalyst system efficiency are required. Therefore, significant system optimization has to be considered. Examples of this include: catalyst development, optimized thermal management, advanced urea dosing calibrations, and optimized SCR inlet NO:NO2 ratios. The aim of this paper is to provide a thorough system screening using a range of advanced SCR technologies, where the pros and cons from a system perspective will be discussed. Further optimization of selected systems will also be reviewed. The results suggest that current legislation requirements can be met for all SCR catalysts under investigation.

An effective way of meeting future emission legislation with a heavy-duty diesel engine is to equip the engine with an EGR-system combined with a particulate trap. In this study the work was concentrated on the EGR-system. The goal of the investigation was to find an EGR-system that could deliver enough air and exhaust gases to the engine to meet the Euro IV emission levels with minimum penalty on engine performance and fuel consumption, starting from a Euro 0 engine. The tests showed that it was possible to significantly improve emissions with all the tested EGR-systems in combination with a particulate trap, but notable differences with respect to fuel consumption were found. For all EGR systems under study, the main factors influencing engine performance and fuel consumption were found to be. Pumping losses. Residual gases. Temperature of the recirculated exhaust gases. Distribution of the recirculated exhaust gases between the cylinders