Effects of Adjustable Two-Stage Supercharging and EGR Strategy on Performance of Miller Cycle Diesel Engine

CHENG Xiaobei; PU Han; YANG Can

doi:10.3969/j.issn.1001-2222.2019.04.001

Vehicle Engine ›› 2019, Vol. 0 ›› Issue (4) : 1-7. DOI: 10.3969/j.issn.1001-2222.2019.04.001

Effects of Adjustable Two-Stage Supercharging and EGR Strategy on Performance of Miller Cycle Diesel Engine

CHENG Xiaobei¹,PU Han²,YANG Can¹

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Abstract

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 ebooster technology. The effects of Miller degree, two-stage supercharging strategy and EGR on diesel engine performance and NO_x 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 NO_x 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 ebooster 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 NO_x emission. EGR can avoid the side effects caused by higher intake pressure and reduce the mechanical load and NO_x emission of diesel engine. BMEP_AC increases by 0.03 MPa and NO_x emission reduces by 0.47 g/(kW·h) when Miller degree,p_in，π_Hand EGR is M30, 0.286 MPa, 7% and 10% respectively, which improves the combustion and NO_x emission of diesel engine effectively.

Key words

Miller cycle / e-booster / EGR / NOx / diesel engine

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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 https://doi.org/10.3969/j.issn.1001-2222.2019.04.001