Numerical Investigation on Effects of Assigned EGR Stratification on a Heavy Duty Diesel Engine with Two-Stage Fuel Injection

Zhaojie Shen, Wenzheng Cui, Xiaodong Ju, Zhongchang Liu, Shaohua Wu and Jianguo Yang
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Zhaojie Shen: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Wenzheng Cui: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Xiaodong Ju: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China
Zhongchang Liu: State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130025, China
Shaohua Wu: School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
Jianguo Yang: School of Automotive Engineering, Harbin Institute of Technology, Weihai 264209, China

Energies, 2018, vol. 11, issue 3, 1-14

Abstract: External exhaust gas recirculation (EGR) stratification in diesel engines contributes to reduction of toxic emissions. Weak EGR stratification lies in that strong turbulence and mixing between EGR and intake air by current introduction strategies of EGR. For understanding of ideal EGR stratification combustion, EGR was assigned radically at ?30 °CA after top dead center (ATDC) to organize strong EGR stratification using computational fluid dynamics (CFD). The effects of assigned EGR stratification on diesel performance and emissions are discussed in this paper. Although nitric oxides (NO x ) and soot emissions are both reduced by means of EGR stratification compared to uniform EGR, the trade-off between NO x and soot still exists under the condition of arranged EGR stratification with different fuel injection strategies. A deterioration of soot emissions was observed when the interval between main and post fuel injection increased, while NO emissions increased first then reduced. The case with a 4 °CA interval between main and post fuel injection is suitable for acceptable NO and soot emissions. Starting the main fuel injection too early and too late is not acceptable, which results in high NO emissions and high soot emissions respectively. The start of the main fuel injection ?10 °CA ATDC is suitable.

Keywords: injection timing; exhaust gas stratification; diesel combustion; emissions (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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