Effect of Pilot Injection Strategy on Performance of Diesel Engine under Ethanol/F-T Diesel Dual-Fuel Combustion Mode

To reduce emissions and save energy, alternative fuel and dual-fuel mode have been widely applied in the field of diesel engines. The pilot injection has potential to reduce engine vibration noise and pollutant emissions. The effects of a diesel fuel pilot injection strategy on the performance of an ethanol/F-T diesel dual-fuel engine were experimentally investigated on a four-cylinder four-stroke common rail diesel engine modified with an ethanol injection system. The results indicate that the variation in the combustion characteristic parameters with pilot injection timing is nonlinear and the difference is small, while soot, NOx, and CO tend to decrease, with an increase in pilot injection timing. With the increase in pilot injection amount, pmax, combustion duration, CO and soot increased; pmax phase and CA50 were closer to TDC; HRRmax and the ignition delay period decreased. The BSFC tends to increase with the increase in pilot injection timing and the increase in pilot injection amount, while the BTE shows the opposite trend. The value and the variation range of COVpmax are small. The effect of the pilot injection amount on ethanol/F-T diesel dual-fuel engine is more significant. The research presented in this paper can provide reference directions for the formulation of a fuel injection strategy of ethanol/F-T diesel dual-fuel combustion mode to reduce NOx without worsening the combustion process and presenting an insufficient fuel economy.