Effects of Miller cycle and variable geometry turbocharger on combustion and emissions in steady and transient cold process. (25th May 2017)

• Record Type: Journal Article
• Authors: Wu, Binyang; Zhan, Qiang; Yu, Xiaoyang; Lv, Guijun; Nie, Xiaokun; Liu, Shuai
• Is Part Of: Applied thermal engineering. Volume 118(2017)
• Page Start: 621
• Page End: 629
• Publication Date: 2017-05-25
• Subjects: BMEP brake mean effective pressure -- BTE brake thermal efficiency -- CO carbon monoxide -- EGR exhaust gas recirculation -- HC hydrocarbon compounds -- HCCI homogeneous charge compression ignition -- IMEP indicated mean effective pressure -- IVCT intake valve closing timing -- ITEg gross indicated thermal efficiency -- LIVC late intake valve closing -- Φ equivalence ratio -- NOx nitrogen oxides -- VGT variable geometry turbine -- ROHR rate of heat release; Miller cycle -- Variable geometry turbocharger -- Transient condition -- Dynamic response -- Emission; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2017.02.074
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Miller cycle and two-stage turbocharge are applied to HD diesel engine. The goal is to assess the potential of the techniques in the transient process. Compared to steady-state map, soot peak emissions are reduced by 50%. NO x peak emissions are reduced by 10% compared to the conventional cycle. Abstract: The influence of Miller cycle and variable geometry turbocharger (VGT) on combustion and emissions was investigated in steady and transient operation of a heavy-duty diesel engine. The experiment was conducted on a six-cylinder diesel engine with common rail fuel injection, two-stage turbocharger and Miller cycle. The results revealed that Miller cycle decreased soot and nitrogen oxides (NO x ) emissions and increased brake thermal efficiency (BTE) in certain operation. In the steady operation, the intake flow was reduced in a cold condition because the low oil temperature led to the hydraulic mechanism delay intake valve closing timing. However, by adjusting VGT, low emissions of soot and NO x could still be obtained with relatively high BTE. In cold transient process, dynamic response of torque depended on indicated work and gas pumping work. A good trade-off performance could be achieved by maintaining the initial VGT rack position for 0.5 s. Compared to VGT variation under the steady-state map, soot peak emissions were reduced by 50% with NO x emissions nearly unchanged by VGT control strategy 3 and Miller cycle. Compared to diesel conventional cycle, the combination of Miller cycle and VGT control strategy 3 can not only ensure quick dynamic torque response, but also reduce NO x peak emissions by 10% with slightly increased soot peak emissions.