Numerical Study on Flame Structure and NO Formation Characteristics in Oxidizer-controlled Diffusion Flames

초록

A numerical study with a detailed chemistry has been conducted to investigate the flame structure and NO formation characteristics in oxygen-enriched (CH4/O2) and oxygen- enriched-EGR (CH4/O2-CO2) counter diffusion flames with various strain rates. A small amount of N2 is added to oxygen-enriched-EGR flame, in order to consider the inevitable N2 contamination by O2 production process or air infiltration. The results are as follows : In CH4/O2-CO2 flame, it is very important to consider a radiation effect specially at low strain rates. In CH4/O2 flame, NO emission responds very sensitively to a small amount of N2 contamination and increasing flame stretch is expected to be an effective method to decrease EINO. The role of thermal mechanism to NO production rate in CH4/O2 flame is different from that in CH4/Air flame. In case CH4/O2-CO2 flame contains more than 40% of CO2, it is possible to accomplish a higher temperature than that of CH4/Air flame under the same EINO condition.