Numerical study on soot formation in methane/<i>n</i>-heptane laminar diffusion flames under an oxygen-rich environment at elevated pressure

作者：Junlong Liu, Zhancheng Dou, Yujuan Li, Xingdong Su, Jinfang Yao, Wenlong Dong, Huaqiang Chu · 发表于：Progress in Reaction Kinetics and Mechanism · 年份：2025 · DOI：10.48130/prkm-0025-0023 · 被引用次数：3 · 研究领域：Advanced Combustion Engine Technologies、Combustion and flame dynamics、Catalytic Processes in Materials Science

High-pressure and oxygen-enriched combustion technologies markedly elevate thermal efficiency, promote complete combustion, and mitigate the heat loss attributable to elevated temperatures in internal combustion engines. This study examined soot formation in methane/ n -heptane dual-fuel under high-pressure oxygen-enriched conditions at 2 atm by utilizing the CoFlame code. With the oxygen index (OI) atmosphere rising from 21% to 37%, the soot volume fraction (SVF) increased 2.4-fold, and the peak flame temperature rose from 2,199.2 to 2,548.8 K. In addition, the temperature of the methane/ n -heptane flame decreased with the increase in the OI content downstream of the flame. An increase in the OI extended the soot formation region of methane/ n -heptane flames and relocated the maximum point of the flame axis volume fraction closer to the nozzle. As the OI rose, peak H radical fractions increased from 2.67 × 10 −3 to 4.10 × 10 −3 , an increase of 53.6%. Under a high OI, the H mole fraction exhibited radial growth, which correlated with suppressed soot formation. Nevertheless, the markedly greater mole fraction of acetylene relative to H atoms led to net growth outweighing the inhibitory effects. The elevated oxygen concentration in the reaction zone raised the OH peak concentrations, accelerating the oxidation of soot while simultaneously reducing the visible soot height. As the OI increased, A1 peak concentrations rose from 0.00048046 to 0.00070802, up by 47.4%.