Experimental investigation of engine characteristics and exhaust emissions in a diesel engine operated in homogeneous charge diesel combustion principle

In the present thesis, the effects of gasoline fumigation (GF) on engine characteristics, combustion, heat release rate (HRR), exhaust emissions and total fuel cost have been experimentally investigated on an automotive diesel engine. Here, experiments have been carried out for five different fumigation ratios such as 0, 5, 10, 15 and 20%, five different engine speeds and two different compression ratios. An adapted carburetor was mounted on the intake manifold of the engine to introduce gasoline into intake air. The original compression ratio of the engine is 18.25 and it was reduced to 17 by using a thicker cylinder head gasket. It was determined that; specific fuel consumption and the total fuel cost decreased and effective efficiency increased significantly in all of the selected operating conditions with the application of BF for both compression ratios. Nitrogen oxides generally decreased with BF at 2000 and 2500 rpm but they generally increased with BF at 3000, 3500 and 4000 rpm. Opacity decreased until 10% GF ratio, but after this ratio it started to increase again. It was observed that; HRR graphs of GF are different from HRR graphs of neat diesel fuel (NDF) for both of the compression ratios. There has been only one peak (maximum HRR point) at the NDF graphs after top dead center (TDC) but have been two at the GF graphs; one before TDC and one after TDC. As the GF increased; the height of the first peak increased and the height of the second peak decreased and also combustion duration decreased.