Due to the low fresh charge and insufficient torque output of Miller cycle Diesel engine, the effects of adjustable two-stage supercharging and EGR strategy on the performance of Miller cycle diesel engine were discussed after the introduction of ebooster technology. The effects of Miller degree, two-stage supercharging strategy and EGR on diesel engine performance and NOx emission at 1 400 r/min with BMEP of 1.85 MPa were analyzed. The results show that the in-cylinder combustion temperature gradually decreases with the reduction of NOx emission and the torque output also reduces due to the reduction of charge with the deepgoing Miller cycle under early intake valve closing (EIVC) or late intake valve closing (LIVC) strategy. Controlling the ebooster properly to increase the intake pressure can compensate for the shortage of Miller cycle torque output and improve fuel economy, but it can also lead to the increase of maximum pressure and NOx emission. EGR can avoid the side effects caused by higher intake pressure and reduce the mechanical load and NOx emission of diesel engine. BMEPAC increases by 0.03 MPa and NOx emission reduces by 0.47 g/(kW·h) when Miller degree,pin，πH and EGR is M30, 0.286 MPa, 7% and 10% respectively, which improves the combustion and NOx emission of diesel engine effectively.
CHENG Xiaobei
,
PU Han
,
YANG Can
. Effects of Adjustable Two-Stage Supercharging and EGR Strategy on Performance of Miller Cycle Diesel Engine[J]. Vehicle Engine, 2019
, 0(4)
: 1
-7
.
DOI: 10.3969/j.issn.1001-2222.2019.04.001
