This paper is to review the potential of exhaust gas recirculation（EGR） to reduce the exhaust emissions

particularly NOx emissions

and to delimit the application range of this technique. A detailed analysis of results of EGR effects on the emissions and performance of Diesel engine

from the deep analysis

it was found that adding EGR to the air flow rate to the Diesel engine rather than displacing some of the inlet air. This way may allow exhaust NOx emissions to be reduced substantially. The use of EGR is

therefore

believed to be most effective in improving exhaust emissions.