Experimental research on the effects of kerosene on the pre-injection spray characteristics and engine performance of dual-direct injection diesel Jet Controlled Compression Ignition mode

This work is focused on the effect of the kerosene blended pre-injection fuels on the liquid spray characteristics and engine performance based on the dual-direct diesel Jet Controlled Compression Ignition (JCCI) mode. In this mode, the blended fuels of diesel, gasoline, kerosene and ethanol were directly injected into the cylinder to prepare the premixed charge, which was ignited by the direct jet-injection diesel. The spray visualization experiments with D15K15 and D30 were carried out on the constant volume bomb platform under the typical pre-injection conditions. Then the engine experiments were conducted under four engine load conditions on the modified 186FA diesel engine platform. The visualization results reveal that the kerosene component with lower end boiling point, kinetic viscosity and surface tension in the blended fuels can promote the breakup and evaporation of fuel droplets and improve the fuel-air mixing process. Therefore, the liquid spray penetration distance, the cone angle and the spray area of D15K15 are reduced compared to that of D30. The engine experimental results show that there is almost no difference between the combustion and emission performance with these two pre-injection fuels under lower engine load conditions. However, the pre-injection fuels with 15 wt% kerosene shorten the first stage combustion duration and advance the combustion phasing, both the indicated thermal efficiency and nitrogen oxides emissions are increased. On the other hand, the total hydrocarbons and CO emissions are reduced obviously at higher engine loads due to the reduced wall-wet issues and the increased in-cylinder temperature.