Abstract
Exhaust gas recirculation (EGR) is a well established approach for NOx emission reduction. Researchers have observed 30 % to 75 % reductions in NOx when using 5 % to 25 % EGR rates. Although there has been extensive experimental research on emission formation by the application of EGR, little has been devoted to the diesel combustion process. An attempt was made to study experimentally the combustion process at different EGR rates and engine loads. A heavy duty 4-cylinder 7,2 litre turbocharged diesel engine was used for the tests and a low pressure
EGR concept was applied where the EGR rate was controlled by an EGR valve. In-cylinder pressure traces were measured and analysed. A one-zone combustion model was used to compute the rate of heat release from the experimental results. Several combustion parameters such as ignition delay, duration of pre-mixed and diffusion flame, combustion duration, etc., were determined and carefully studied, and basic correlation is presented and discussed in this paper.