Influence of equivalence ratio and colorless distributed combustion on combustion characteristics and emissions in a heavy-duty natural gas-fueled converted engine
INTERNATIONAL JOURNAL OF ENGINE RESEARCH, cilt.0, sa.1, ss.1-21, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 0 Sayı: 1
- Basım Tarihi: 2026
- Doi Numarası: 10.1177/14680874261467506
- Dergi Adı: INTERNATIONAL JOURNAL OF ENGINE RESEARCH
- Derginin Tarandığı İndeksler: Scopus, Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest), Science Citation Index Expanded (SCI-EXPANDED), Compendex, INSPEC
- Sayfa Sayıları: ss.1-21
- Gazi Üniversitesi Adresli: Evet
Özet
The conversion of heavy-duty diesel engines to natural gas spark-ignition engines offers a promising solution for improving engine performance and sustainability. However, it also introduces the challenge of high NOx emissions because of high compression ratios. This study aims to achieve ultra-low emissions by investigating the combined effects of equivalence ratio and Colorless Distributed Combustion (CDC) strategy with a three-dimensional numerical simulation. Specifically, the research focuses on the performance and emissions characteristics of a heavy-duty diesel engine converted to spark-ignition operation using methane fuel. To address this objective, three equivalence ratios (0.6, 0.7, and 0.8) were examined under varying oxygen concentrations (23%, 21%, 19%, 17%, and 15% by mass), where dilution was achieved by introducing nitrogen (N2) as an inert diluent to promote distributed combustion conditions. A three-dimensional computational fluid dynamics (CFD) model incorporating a reduced methane chemical mechanism was employed to capture in-cylinder flow, heat release, and pollutant formation. The G-equation combustion model was coupled with the RNG k-ϵ turbulence model to simulate the propagation of lean premixed turbulent flames. The CDC regime effectively minimized NOx emissions across all equivalence ratios, with the most favorable balance between efficiency and emissions observed at φ = 0.7 and an oxygen concentration of 19%. These findings provide insights into the optimization of lean CDC strategies in compression ignition engines converted to gas-fueled spark-ignition systems for cleaner combustion.