• A comprehensive numerical study was performed on hydrogen-enriched biogas combustion using a validated CFD framework. • Hydrogen addition (10–40 vol.%) significantly enhanced flame stability, ignition characteristics, and heat release compared with pure biogas. • Moderate hydrogen enrichment (20%) produced the highest and most uniform axial temperature distribution across all operating conditions. • Increasing the excess air coefficient from fuel-rich to slightly lean conditions improved oxidation completeness and reduced CO emissions. • Optimal combustion performance was achieved at α ≈ 1.09 with 20% hydrogen enrichment, balancing thermal efficiency and low pollutant emissions. Hydrogen enrichment is a pivotal strategy to augment the combustion characteristics of biogas, addressing its inherent limitations of low calorific value and sluggish flame propagation. This study presents a rigorous numerical investigation into the synergistic effects of hydrogen blending ratios (10%, 20%, and 40% by volume) and air excess ratios ( α = 0.8, 0.99, 1.09, 1.19) on the thermochemical performance of a biogas-fueled system (65% CH 4 / 35% CO 2 ). The results demonstrate that hydrogen enrichment significantly enhances combustion efficiency and flame stability while facilitating thorough oxidation. A peak axial temperature of 1591 K was recorded for the 20% H 2 blend under stoichiometric conditions, representing the optimal thermal output. As the air excess ratio transitioned from sub-stoichiometric (0.80) to lean conditions (1.19), a controlled thermal reduction was observed, which effectively optimized flame stability and mitigated localized hotspots. Quantitatively, the study identifies α = 1.09 with 20% hydrogen enrichment as the optimal operating configuration, yielding the best compromise between high thermal efficiency and minimal pollutant emissions. Under these conditions, CO emissions were significantly curtailed, while peak temperatures remained below the critical threshold for significant Thermal-NO x formation via the Zeldovich mechanism. These findings provide a high-fidelity physical benchmark for the design of sustainable, low-emission energy conversion systems, bridging the gap between traditional CFD analysis and future AI-driven combustion optimization.
Mizher et al. (Sat,) studied this question.