A Compact Temperature Control System for Lean Exhaust Gas to Improve Conversion Performance of NOx Aftertreatment

A compact exhaust gas temperature control unit is presented. The unit was fitted to a gasoline direct injection production car together with a modified exhaust system. It was shown that it was possible to keep the exhaust gas temperature within the lean operational NO_x temperature window of typical NO_x absorption catalysts for the whole European drive cycle. This should improve the lean NO_x conversion of such a catalyst system significantly. It was shown that the standard vehicle cooling system should be able to cope with the additional heat input from the temperature control unit without major modifications.