Study On NO_x Reduction Of Two-Stroke Diesel Engine By EGR Combined With Miller Cycle

The Tier III criterion will be carried out in 2016,in which NOx should be reduced by 75% comparied with Tier II.It proposed even high requirements for marine engines.This paper set up the simulation model of HHM 6S350,studied exhaust gas recirculation(EGR),miller cycle,by-pass single turbocharging and two-stage turbocharging systems' affects on NOx reduction and specific fuel consumption.First,high-pressure EGR system is chosen and EGR's influence on cylinder pressure,heat release rate,NOx emission and fuel comsuption is analyzed.Afterwards,by-pass single turbocharging system is designed,EGR pipe parameters is calculated,by-pass mass flow rate's influence on turbocharging system,combustion progress and EGR rate is studied,Tier III mode's fuel consumption is analyzed.Lastly,miller cycle's influence on low speed engine is studied,a two-stage turbocharging system is matched and EGR is combined,finally 6S350 reaches Tier III criterion and specific fuel consumption doesn't goes very high.