Experimental Investigation on Soot Formation in an Ethylene/Air Laminar Diffusion Flame Diluted with CO2 at Pressures up to 8 atm

The effects of CO2 addition to the fuel on the temperature field and soot formation in a co-flow laminar diffusion flame of ethylene/air over the pressure range of 1 to 8 atm were investigated experimentally. The flame was produced in a high pressure combustion chamber. A technique of diffuselight two-dimensional line-of-sight attenuation (diffuse 2D-LOSA) was applied to measure soot volume fraction distribution in the flame. The influence of CO2 dilution on flame appearance at various pressures was investigated. The quantity of soot formation decreases with the increase in CO2 addition at all pressures, with the decrease rates being slower under higher pressure than lower pressure. With the addition of CO2 to fuel side, the sooting zone decreases and tends to be concentrated toward the tip of flame. Generally, the overall soot temperatures of the CO2 dilution flames decrease with increasing pressure and CO2 addition, the most significant change in the lower and middle of the flame. At same pressure, the CO2 addition has little impact on the flame height. As the pressure rises, however, the axial diameter of flame decreases to give an overall stretched appearance. (C) 2016 American Institute of Chemical Engineers Environ Prog, 36: 476-482, 2017