Exhaust Gas RecirculationThe term exhaust gas recirculation refers to the carefully regulated process of feeding exhaust gas back into the combustion chamber. Exhaust gas recirculation is an effective method of reducing the nitrogen oxide (NOx) levels at the combustion stage. When the fuel/air mixture burns, the formation of nitrogen oxides increases at a disproportionately high rate as the combustion temperature rises. Recirculating a portion of the exhaust gas back to the combustion chamber lowers the combustion temperature inside the cylinder, thereby reducing the rate of nitrogen oxide formation. The emission characteristics can therefore be influenced as the engine load conditions change by the regulated addition of exhaust gas to the fuel/air mixture. With exhaust gas recirculation, the exhaust gas is directed back into the intake tract via a system of pipes with the aid of a valve controlled electronically by the engine management unit; from there it is drawn back into the combustion chamber. |
