Study on optimization of Two-stage Post Injection under PCCI Combustion

Yoji Hiraiwa･Yukito Watanabe (Hokkaido university, Graduate School of Engineering)･Gen Shibata･Hideyuki Ogawa (Hokkaido university, Research Faculty of Engineering)

Single post injection under the homogeneous in-cylinder conditions generated by PCCI combustion has been shown to be effective in suppressing partial oxidation of the fuel. In this study, Two-stage post injection was introduced under PCCI combustion with the aim of reducing fuel adhesion to the cylinder wall due to weakened spray penetration and efficiently supplying unburned hydrocarbons for DPF regeneration. The optimal DPF regeneration was investigated under PCCI combustion through engine experiments and 3D-CFD analysis.

Effect of the pilot injection on Ignition and Combustion Characteristics of Pentanol in a Common Rail Type Small DI Diesel Engine

Masaki Hirata･Koji Uchida･Hironori Saitoh (sojo University)

This study deals with the development of controlled-ignition technology for high-performance compression-ignition alcohol engines. The objective of this study is to make clear the effect of the pilot injection on the ignition and combustion characteristics of pentanol in a common rail type small DI diesel engine. Experiments were carried out by varying the pilot injection duration and hot EGR ratio under the condition of higher compression ratio (ε=23) in comparison with the original one (ε=18.5). Higher compression ratio was achieved by reducing the volume of combustion chamber formed on the top of the piston.

The Effects of Lower Boiling Point Hydrocarbons in the Diesel Oil on Combustion and Exhaust Gas Emissions Characteristics in a Heavy Duty Diesel Engine

Kunihiro Shimizu･Tomohiro Matsuda･Jin Kusaka (Waseda University)

This study investigates the impact of synthetic fuel properties on improving the combustion and emissions of high-compression-ratio (CR) heavy-duty diesel engines. Diesel, DP2b (Diesel + C6H14: 6:4 vol%), and DP3b (diesel + nC7H16: 6:4 vol%) fuels are tested in a single-cylinder CR=23 engine. Combustion, NOx, and soot are compared under various engine speeds/loads, EGR, and injection timings. A 3D-CFD model was calculated using CHEM-KIVA4 and Waseda’s phenomenological soot model. The results show that DP2b and DP3b generate similar NOx, but soot can be reduced by 25-62% compared to diesel, thanks to the low aromatic content and boiling points.

Effect of fuel ignitability and aromatic components on crystallite size of soot particles from a diesel engine

Yu Kuroshima･Yuki Yamakura･Mizuki Obara (Graduate School of Kitami Institute of Technology)･Kazuki Inaba･Kazuhiro Hayashida (Kitami Institute of Technology)

The effect of fuel ignitability and aromatic contents on the crystallite size of soot particles in a single-cylinder diesel engine were investigated. The influence of cetane number on the crystallite size was minimal for fuels consisting of paraffinic hydrocarbons. Differences were observed in the heat release rate profile during the premixed combustion period between fuels where paraffinic hydrocarbons were blended with diesel fuel and those blended with toluene as an aromatic component, attributable to variations in ignitability. However, the heat release rate profiles during subsequent combustion period showed no significant differences. A reduction in aromatic content led to decreased smoke emissions and a smaller crystallite size in soot particles.