Investigation Of The Effects Of Combustion System Parameters On The Performance Of Diesel Low Temperature Combustion

Low Temperature Combustion(LTC) as a method of meeting increasingly stringent emission regulations received widespread attention in recent years.Low Temperature Combustion can lower combustion temperature,produce more homogeneous mixture and reduce NOx and SOOT emissions simultaneously which can be realized by means of heavy exhaust gas recirculation (EGR),charge air colling and increasing injection pressure etc. with fuel normally or slightly earlier injected.So the possibility of achieving LTC and the fundamental theory was systematically investigated at medium to high load with numerical simulation method,including the effects of EGR and combustion system parameters on combustion process and emissions.Firstly,in order to set the initial conditions accurately,the relationship between in-cylinder fractions and EGR or excess air ratio was built.By means of studying the effects of EGR and combustion system parameters on combustion process and emissions,the following results were obtained:EGR can effectively decrease NOx emissions but with an increase of SOOT and CO emissions.So the effects of combustion system parameters were investigated with a certain EGR ratio at which SOOT emissions increase notably.With increased intake pressure,the excess air ratio increased, SOOT and CO emissions decreased but NOx emissions increased.The injection parameters have a great influence on combustion process and emissions,with increased injection pressure and advanced injection timing,SOOT and CO emissions decreased notably but NOx emissions increased,the fuel economy was improved.Swirl ratio can influence combustion process and emissions by means of intensifying the flow of in-cylinder gas and improving the fuel-air mixing.