Influence of fuel system variations on performance and emission characteristics of combined air-wall-guided mode modified GDI engine with alcoholic fuels and exhaust gas recirculation.

Abstract

GDI engines commercially existed with spray-guided mode where the fuel injector placed almost vertically and sprayed fuel is occupied throughout the volume of combustion chamber. With the advanced emission norms, NOx and soot emissions control is the major task along with lower fuel consumption. To achieve the advanced emission norms, further modifications are required before or during combustion. Combined air-wall guided mode combustion chamber modification is the advanced stage required for further improvement in mixing and superior combustion. Combined air-wall guided mode involved piston crown shape modification so that the modified shape must impart turbulence effects and divert the fuel/mixture flow towards the spark plug tip to initiate the combustion process. In this study, the combined air-wall-guided mode gasoline direct injection engine was tested with gasoline blends using ethanol, methanol and N-butanol at 20, 35 and 50% proportions under specific fixed conditions: 1500rpm speed, 10% EGR and FIP of 150 bars with three split injections at 320°, 220° and 100° before TDC at different injection durations. Tests were conducted over these gasoline blend proportions for engine performance and emission characteristics and achieved the beneficial results with E20 gasoline blend over the entire applied torque values. E20 blend develops maximum IMEP of 8.3% at 50% blend proportion and as significant increment of 7.4% at 20% of blend proportion. E20 blended fuel shown a maximum decrement of SFC up to 7.2%. Significant reduction of CO emission up to 11.3% for E20 blend and maximum reduction of 12% for E50 blend. HC emissions were decreased significantly up to 14% for E20 blend and it reached maximum reduction of 20.3% for E50 blend. NOx emissions showed lower concentrations for E20 blend with a decrement of 13.3% and higher for B35 blend. Soot particle emissions were decreased significantly up to 27% for E20 blend and it reached maximum reduction of 33.34% for E50 blend.