Lean methane-hydrogen and methanol-hydrogen spark-ignition combustion phasing with orientation-driven control
Energy, vol.361, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 361
- Publication Date: 2026
- Doi Number: 10.1016/j.energy.2026.141973
- Journal Name: Energy
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Applied Science & Technology Source, Compendex, Environment Index, Geobase, INSPEC, Public Affairs Index, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Keywords: Alternative fuels, Combustion phasing, Hydrogen combustion, Injection angle, Methane-hydrogen mixture, Methanol-hydrogen mixture
- Yıldız Technical University Affiliated: Yes
Abstract
The current study numerically investigates hydrogen injection angles in lean dual-fuel spark-ignition engines. The hydrogen injection angle in the combustion engine is considered as an independent geometric control parameter governing combustion phasing. For this purpose, three-dimensional CFD simulations have been performed in CONVERGE 4.0 for two single-cylinder configurations of 0.33 L and 0.50 L with a compression ratio (CR) of 9.0. The fuel mixtures employed are methane-hydrogen (CH4–H2) and methanol-hydrogen (CH3OH–H2), at excess air ratios of λ = 1.4, 1.6, and 1.8. Hydrogen is directly injected at 40°, 60°, and 85° relative to the cylinder axis, while maintaining fixed ignition timing at 318 crank angle degrees (CAD) and constant injection timing to isolate stratification effects. Quantitative combustion metrics and heat release rate (HRR) are analyzed. In the 0.50 L configuration, peak HRR exceeded 200 J/deg for CH3OH–H2 at λ = 1.4, compared to 120–140 J/deg in the 0.33 L chamber. At λ = 1.8, CH4–H2 in the 0.33 L chamber failed to sustain stable combustion (HRR <5 J/deg), whereas CH3OH–H2 maintained measurable heat release (10–11 J/deg). Piston-oriented injection (85°) advanced combustion phasing and increased peak HRR under highly lean conditions, while spark-oriented injection (40°) produced delayed and more distributed heat release. CO emissions reached 1200–1400 ppm in the 0.33 L chamber at λ = 1.8 but remained below 800 ppm in the 0.50 L configuration. NOx peaked at λ = 1.4 (5000–8000 ppm) and decreased sharply with increasing dilution. In addition, injection angle-induced combustion phasing variations significantly affected NOx formation; in the 0.33 L chamber at λ = 1.4, the CH4–H2 40° configuration produced only ∼81 ppm NOx, whereas the 60° and 85° configurations produced ∼3743 ppm and ∼5630 ppm, respectively, due to differences in HRR development and local burned-gas temperature. Unlike previous studies that simultaneously varied ignition timing, the present study isolates hydrogen injection angles as an independent geometric combustion-control parameter under fixed operating conditions. Results demonstrate that hydrogen injection angle provides a physically interpretable and design-relevant mechanism for controlling mixture stratification, advancing combustion phasing, and extending lean operating limits in hydrogen-assisted dual-fuel engines.