Numerical Analysis of Soot Dynamics in C3H8 Oxy-Combustion with CO2 and H2O

Oxygen-enriched combustion is increasingly recognized as a viable approach for clean energy production and carbon capture, offering substantial benefits for boosting combustion efficiency and mitigating pollutant emissions, which makes it widely adopted in various industrial applications. Liquefied petroleum gas (LPG), predominantly consisting of propane (C3H8), is commonly utilized in numerous combustion systems, yet its emissions of soot particulates have raised considerable environmental concerns. This study delves into the combustion dynamics and soot formation behavior of propane, the principal component of LPG, under oxy-fuel combustion conditions, with the inclusion of H2O and CO2, utilizing both experimental techniques and numerical simulations. The results reveal that CO2 and H2O suppress soot formation through distinct mechanisms. CO2 decreases soot nucleation and surface growth by lowering flame temperature and H atom concentration, but it minimally enhances soot oxidation. H2O significantly reduces soot formation by chemically increasing OH radical concentration, thereby enhancing soot oxidation. A detailed decoupling analysis further shows that CO2’s influence is predominantly thermal and chemical, resulting in lower OH levels and an elongated flame shape. In contrast, H2O’s substantial thermal and chemical effects decrease flame height and promote soot reduction. These insights advance the understanding of soot formation control in oxy-fuel combustion, offering strategies to optimize combustion efficiency and minimize environmental impact.