Exhaust gas recirculation (EGR)

The reduction of pollutant emissions—particularly of nitrogen oxide emissions in diesel engines—is an important task within the development process. Engine-internal methods such as exhaust gas recirculation seek to reduce raw emissions during combustion itself.

EGR coolers

The new emissions standards for diesel passenger cars and commercial vehicles can no longer be met with adjustments to the engine alone. One approach to complying with the new emissions limits is to incorporate cooled exhaust gas recirculation (EGR). This involves extracting a portion of the main exhaust flow between the engine outlet and the turbine, cooling it in a special heat exchanger, and feeding it back to the intake air downstream of the charge air cooler. The combustion temperature in the engine is thereby lowered, thus reducing the formation of nitrogen oxides (NOx). The cooled EGR technology has been available in series production passenger cars since1999. In gasoline engines, cooled EGR will be implemented in the coming years to reduce fuel consumption. One outstanding feature of MAHLE’s laser-welded exhaust gas heat exchangers is their excellent corrosion resistance.

We also offer switchable exhaust gas heat exchangers featuring a bypass section integrated into the cooler housing. To keep pollutant emissions at a constantly low level, the bypass disables the recirculated exhaust gas cooling function in certain driving situations, e.g., during the cold start phase.

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