Effect of CO2 and O2 enhancement and gravity variations on normal and inverse laminar diffusion flames

Abstract

Steady-state global chemistry calculations for 15 different flames in both normal earth gravity and micro-gravity conditions are implemented using an axi-symmetric CFD code. 9 different normal laminar diffusion flames of methane-air in normal earth gravity condition with varying CO2 mole fraction have been implemented using 5.5 mm diameter burner. Out of these 9 different flames, 4 flames are different mole fraction of CO2 dilution in fuel (20%, 30%, 40%, 50% CO2 and rest are CH4), 4 flames are different mole fraction of CO2 in air inlet (50%, 60%, 70%, 79% CO2 and rest are O2) and 1 flame is methane-air (21% O2 and 79% N2). The effect of CO2 enhancement in fuel and air inlet on flame shape, size and maximum temperature has been described in this paper. Additionally, 6 different inverse laminar diffusion flames of ethane-air with varying O2 mole fraction (21%, 30%, 50% O2 and rest are N2) with both normal earth gravity and micro-gravity have been implemented using 5.5 mm diameter burner and the maximum temperature results are compared with the available literature. For methane-air normal laminar diffusion flames, effect of CO2 enhancement in both air and fuel inlet cause a decrease in flame temperature. For ethane-air inverse laminar diffusion flames, effect of O2 enrichment in air inlet cause an increase in flame temperature.