• • CO2 dilution at 40% reduced NOx emissions by 95.5% (from 6.7×10-5 to 3.03×10-6 at φ=0.7) and 94.3% at φ=0.9, enabling ultra-low NOx in industrial boilers.
• • Average furnace temperature decreased monotonically with CO2 blending: 1688 K (0%), 1658 K (10%), 1523 K (20%), 1421 K (30%), 1344 K (40%), indicating a 20.4% reduction at 40% CO2.
• • H2 enrichment from 0% to 40% increased peak flame temperature from 2018 K to 2199 K and shifted the peak location from 1.16 m to 0.82 m downstream, enhancing combustion intensity and flame compactness.
• • CO2 blending above 30% increases combustion instability risk; keeping CO2 below 30% balances NOx reduction and stable operation, critical for retrofitting hydrogen-rich natural gas burners.