An Investigation Of Some Combustion Characteristics Of Turbocharged Diesel Engines With Exhaust Gas Recirculation

Abstract

The objective of the present study is to investigate the effect of Exhaust Gas Recirculation (EGR) on ignition delay period, combustion start, and combustion duration in a diesel engine. Study results showed that the ignition delay period increased as the EGR ratio increased because fresh air became less available, resulting in a lower air/fuel ratio which in turn delayed the start of combustion. On the other hand, combustion duration also increased as the EGR ratio increased. Moreover, engine speed also affected combustion characteristics, the ignition delay period increased as the engine speed increased, increased EGR rate reduced fresh charge makes the combustion less efficient which in turn extended the combustion duration. For instance, during the range of engine speeds between 1000 and 4000rpm, the increase of ignition delay period varied from 1.7o to 3.5o Crank Angle (CA). The combustion start was delayed as the engine speed increased, at the 0% EGR setup, the combustion timing ranged between 4.9o to 3.8o CA before Top Dead Center (bTDC) during engine speed from 1000 to 4000rpm respectively. Finally, the combustion duration was increased as the engine speed increased, the duration increased from 36.6o to 55.8o during engine speed from 1000 to 4000rpm respectively.