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A test method, based on parallel sample testing with exhaust fuel injection and certain test procedures, has been developed for diesel lean-NOx catalyst evaluation purposes. The results of the verification tests show uniform distribution of both the exhaust gas and the injected fuel, and a high degree of fuel evaporation. Test procedures are discussed from several points of view. The test method offers a precise and efficient way of testing lean-NOx catalysts on heavy duty diesel engines.

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