Effect of $CO2$ Dilution on Flame Structure and Soot and NO Formations in $CH4$-Air Nonpremixed Flames

In the present work, a numerical analysis has been presented to show the variations in flame structure, flame radiation, and formations of soot and NO in methane-air laminar nonpremixed flames with different $CO2$ dilutions of fuel. It is observed that the flame length reduces as the dilution of the fuel stream by $CO2$ increases while maintaining constant fuel jet velocity at the burner tip. However, the flame length remains almost unchanged with different blends of $CH4$ and $CO2$ if the burner loading (i.e., fuel flow $rate×heating$ value of fuel) is kept constant. Both soot and NO formations decrease monotonically when the $CO2$ fraction in the fuel is increased. The radiation from the flame also decreases when $CO2$ dilution of the fuel is increased, particularly, when the fuel jet velocity is maintained constant.