Experimental and numerical analysis on the influence of direct fuel injection into O2-depleted environment of a GDI-HCCI engine

研究成果: Conference contribution

抄録

Injected gasoline into the O2-depleted environment in the recompression stroke can be converted into light hydrocarbons due to thermal cracking, partial oxidation, and water-gas shift reaction. These reformate species influence the combustion phenomena of gasoline direct injection homogeneous charge compression ignition (GDI-HCCI) engines. In this work, a production-based single-cylinder research engine was boosted to reach IMEPn=0.55 MPa in which its indicated efficiency peaks at 40-41%. Experimentally, the main combustion phases are advanced under single-pulse direct fuel injection into the negative valve overlap (NVO) compared with that of the intake stroke. NVO peak in-cylinder pressures are lower than that of motoring, which emphasizes that endothermic reaction occurs during the interval. Low O2 concentration could play a role in this evaporative charge cooling effect. This phenomenon limits the oxidation reaction, and the thermal effect is not pronounced. For understanding the recompression reaction phenomena, 0D simulation with three different chemical reaction mechanisms is studied to clarify that influences of direct injection timing in NVO on combustion advancements are kinetically limited by reforming. The 0D results show the same increasing tendencies of classical reformed species of rich-mixture such as C3H6, C2H4, CH4, CO, and H2 as functions of injection timings. By combining these reformed species into the main fuel-air mixture, predicted ignition delays are shortened. The effects of the reformed species on the main combustion are confirmed by 3D-CFD calculation, and the results show that OH radical generation is advanced under NVO fuel injection compared with that of intake stroke conditions thus earlier heat release and cylinder pressure are noticeable. Also, parametric studies on injection pressure and double-pulse injections on engine combustion are performed experimentally.

本文言語English
ホスト出版物のタイトルASME 2020 Internal Combustion Engine Division Fall Technical Conference, ICEF 2020
出版社American Society of Mechanical Engineers (ASME)
ISBN(電子版)9780791884034
DOI
出版ステータスPublished - 2021
イベントASME 2020 Internal Combustion Engine Division Fall Technical Conference, ICEF 2020 - Virtual, Online
継続期間: 2020 11 42020 11 6

出版物シリーズ

名前ASME 2020 Internal Combustion Engine Division Fall Technical Conference, ICEF 2020

Conference

ConferenceASME 2020 Internal Combustion Engine Division Fall Technical Conference, ICEF 2020
CityVirtual, Online
Period20/11/420/11/6

ASJC Scopus subject areas

  • 燃料技術
  • 自動車工学
  • 機械工学

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