Effects of Mixture Stratification on Combustion and Emissions of Boosted Controlled Auto-Ignition Engines

Jacek Hunicz, Aymen Tmar and Paweł Krzaczek
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Jacek Hunicz: Faculty of Mechanical Engineering, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin, Poland
Aymen Tmar: National Engineering School of Sfax, University of Sfax, Aeroport Road Km 0.5, BP 1169 .3029 Sfax, Tunisia
Paweł Krzaczek: Faculty of Production Engineering, University of Life Sciences, Gleboka 28, 20-612 Lublin, Poland

Energies, 2017, vol. 10, issue 12, 1-13

Abstract: The stratification of in-cylinder mixtures appears to be an effective method for managing the combustion process in controlled auto-ignition (CAI) engines. Stratification can be achieved and controlled using various injection strategies such as split fuel injection and the introduction of a portion of fuel directly before the start of combustion. This study investigates the effect of injection timing and the amount of fuel injected for stratification on the combustion and emissions in CAI engine. The experimental research was performed on a single cylinder engine with direct gasoline injection. CAI combustion was achieved using negative valve overlap and exhaust gas trapping. The experiments were performed at constant engine fueling. Intake boost was applied to control the excess air ratio. The results show that the application of the late injection strategy has a significant effect on the heat release process. In general, the later the injection is and the more fuel is injected for stratification, the earlier the auto-ignition occurs. However, the experimental findings reveal that the effect of stratification on combustion duration is much more complex. Changes in combustion are reflected in NO X emissions. The attainable level of stratification is limited by the excessive emission of unburned hydrocarbons, CO and soot.

Keywords: combustion engine; low temperature combustion; controlled auto-ignition; direct fuel injection; mixture stratification (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: 2017
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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