Numerical Simulation Study On The Soot Precursor Of The Combustion Of A Diesel Engine With N-butanol-diesel Fuel

With the car quantity increasing,energy shortage and environmental pollution problems have cropped up,so there is an urgent need to find new alternative fuels in order to achieve efficient and clean combustion.The n-butanol by virtue of their own advantages has been widely used in diesel engines,however,how to reduce the soot formation mechanism of diesel engine is not entirely clear.Therefore,this paper through the development of n-butanol-diesel fuel combustion chemical mechanism,adding n-butanol on the soot precursor generation process influence on diesel oil.First of all,the construction of skellysolve includes 101 species and 531 elementary reactions of n-heptane-toluene-n-butanol-PAH in simplified kinetics mechanism and the mechanism of ignition delay and concentration of the components is verified by CHEMKIN software.The results show that the calculated mechanism of toluene/heptane mixture is heptane and n-butanol ignition delay period and in good agreement with the experimental data;n-heptane to ethylene,the n-butanol premixed flame main combustion intermediate products and soot precursor prediction and experimental data basically.Secondly,in order to explore the formation mechanism of butanol and diesel mixed fuel soot precursor,a HCCI engine model using CHEMKIN software,analysis of soot precursors of benzene under different inlet temperature(Ai),naphthalene(A2),phenanthrene(A3),pyrene(A4)of the main reaction path.The results showed that:1)in the initial stage(CA10 time),generated most of the Ai mainly depends on phenol and hydrogen ions or A1-reaction,and the consumption path of Ai is single,which is about 90%Ai phenyl generated in the presence of OH;A2 mainly through the polymerization of two C5H5 oxygen is consumed in the formation.From the sub or under the action of OH;path A3 is the same in different inlet temperature,which is mainly through the reaction of AiC2H-+Ai=C4H3+A3,and then in the hydrogen ions or oxygen ions are consumed;A4 reaction is dominant in the CA10 time,is part of the A4 by A2-the reaction of A1 formation.2)in the middle of the combustion(CA50),the decomposition reaction of Ai mainly depends on the generation of OC6H4CH3,and most of the Ai mainly through the decomposition reaction of Ai=C4H3+C2H3 was consumed;about 99.9%A2 by A2-and the hydrogen ion reaction,most of the A2 in the hydrogen ion or hydroxyl groups under the action of A2-generation is consumed in the intake;when the temperature is 340K,generate most of A3 depends on A3-and hydrogen ion reaction,the inlet temperature is 310K and 370K,A2R5 and C2H2 generation reaction to A3 dominate the consumption path in different intake temperature is the same as A3,most of the A3 by the reaction of A3+H=A3-+H2 consume;A4 in different intake temperature path and consumption path is the same,that most of the A4 via A2R5+C4H2=A4 reaction and A4+H=AiC2H+AiC2H-,A4+H=C2H2+A3-,the two reaction is consumed,but the air temperature is 340K,the dominant role of consumption reaction of A4.Finally,in order to further verify the accuracy of the mechanism,compared with the engine test results.The results showed that the calculated 3D CFD coupling the simplified mechanism of cylinder pressure and heat release rate values agree well with the experimental data,which verified the rationality of this mechanism.