Study On Diesel Jet Controlled Compression Ignition Phase Of Premixed Blends Of Diesel And Gasoline

Premixed Charge Compression Ignition(PCCI)has a great advantage in high efficiency and low emissions combustion of internal combustion engine,but the control of combustion phasing is the main problem of PCCI.Jet Controlled Compression Ignition(JCCI)combustion mode was proposed to control the combustion phasing of PCCI and improve the quality of premixed charge.In this mode,diesel was used as jet fuel to ignite the premixed blends of diesel and gasoline.JCCI engine experiment results show that under the condition of BMEP 0.27 MPa,combustion phasing is line with diesel jet-injection timings over a wide range of crank angel,which incadites this mode can control combustion phasing effectively.Premixed charge of blends of diesel and gasoline is ignited after diesel jet burns.Heat release rate(HRR)changes from slow with single peak value to double peak values,and finally to fast with single peak value with the retarding of pre-injection timing.In the case of fast with single peak value,fuels burn fastest and pressure rise rate is the highest.CA10 s of D10,D30 and D50 are line with diesl jet-injection timings over a wide range of crank angel.Combustion phasing of D10 will advance slightly with diesel jet-injection timings advanved further.In all the experiments of BMEP 0.27 MPa,soot emissions are 0BSU,which indicates this mode can improve premixed charge and reduce soot emissions effectively.JCCI engine simulation results show that premixed blends of diesel and gasoline charge is ignited after diesel jet burns.Nitrogen oxides is mainly generated in diesel jet region where combustion temperature is higher.And nitrogen oxides is generated a little in where premixed blends of diesel and gasoline charge burn.With EGR rate increasing,combustion phasing retards gradually,temperature rise rate and peak temperature decrease.Cylinder pressure peak value and pressure rise rate decrease gradually.Timing of peak cylinder pressure value retards.Nitrogen oxides emission decreases.With the first pre-injection timings advancing,combustion phasings of twice pre-injection is almost the same but later than once pre-injection,fuels is distributed widely in cylinder.The pressure peak value,temperature peak value and nitrogen oxides emission decrease.