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Stringent emissions standards (Euro 6 and Tier2Bin5) lead to the use of nitrogen oxides (NOx) aftertreatment. One of the most widespread technical solutions able to meet these legislations is Urea Selective Catalytic Reduction (Urea SCR). A urea aqueous solution is introduced into the exhaust system in order to reduce NOx over SCR catalyst. Before reaching the catalyst, the aqueous solution has to be transformed into ammonia. Current serial applications need long distances (≻ 400 mm) from injection point to SCR catalyst and a mixer apparatus to ensure sufficient mixing between exhaust gas and ammonia. Because of this distance, SCR catalyst is located far from the engine. The light-off of the catalyst is penalized and therefore the efficiency of the SCR system is low. The purpose of this paper is to show a compact mixing device able to ensure mixing in a short distance (~ 75 mm).

Current emission standards for diesel passenger cars in Europe and the US require the use of diesel particulate filters (DPF). For optimal engine performance the accumulated soot on the filter has to be removed periodically at elevated exhaust gas temperature of 600-650\,DC. Since many driving conditions do not allow such exhaust gas temperature additional measures have to be applied to increase the temperature in the exhaust. Post-injection of diesel fuel in the combustion chamber is the more common solution used to increase the exhaust temperature for particulate filter regeneration. Oil dilution is one of the drawbacks of regeneration by post-injection. The use of a fuel vaporizer is another option to increase the exhaust temperature by introducing fuel in vapor form into the exhaust system. The vaporizer can be located in front of the DOC/DPF either in a close coupled position to the engine or in an underfloor position.