Numerical study of characteristics of confined diffusion flames of synthetic gases in coflow and inverse coflow configurations

Comprehensive numerical predictions of diffusion flames of synthetic gas (syngas) fuels produced from practical reactors, in coflow (CDF) and inverse coflow (IDF) configurations with stoichiometric amount of coflow air are reported for the first time. A numerical model with variable thermo-physical properties, multi-component diffusion, Soret diffusion, detailed chemical kinetics mechanism and an optically thin radiation model has been used. Effect of hydrogen content in fuel, which controls the reactivity, on flame characteristics has been revealed systematically. Higher peak flame temperature is observed in IDF than in CDF. However, its radially averaged temperature peak is lower in IDF than that in CDF within the flame zone. The characteristics of these flames are analysed through reaction rate profiles. Combustion efficiency is higher in IDF than in CDF, for syngas fuels with intermediate reactivity. Understanding the characteristics of these flames will lead to better design of multi-slot burners using mixture of syngas fuels.