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Considering future emission legislation and the global thermal problem, two are the main issues that are of specific concern for the future of the diesel engine, specific gaseous pollutants and CO2 emissions. Both parameters are related to engine bsfc consumption directly or indirectly. The last is becoming even more important considering current fuel prices and the projection for the future indicating a trend for increasing fuel prices. The last decade significant improvement have been accomplished in the field of diesel engine efficiency that has resulted to considerable reduction of engine bsfc. It is obvious that despite improvements in diesel engine efficiency still a considerable amount of energy is rejected to the environment through the exhaust gas. Approximately 30-40% of the energy supplied by the fuel is rejected to the ambience.

A major challenge for researchers and engineers in the field of diesel engine development is the simultaneous reduction of both NOx and soot emissions from diesel engines to comply with strict future emission legislation. One of the promising internal measures that focus on the reduction of soot emissions is post fuel injection which does not have a serious effect on NOx emissions. The main parameters involved when using this technique are post fuel quantity and dwell angle between the main and the post fuel injection events. In the present work a detailed computational investigation has been conducted to determine the effect of post fuel injection on engine performance and pollutant emissions (NOx and soot). To this scope, a phenomenological multi-zone combustion model has been used, properly modified to take into account the interaction of post and main injected fuel amounts.