Synergistic Effect of Mixing Ethylene with Propane on the Morphology and Nanostructure of Soot in Laminar Coflow Diffusion Flames

Abstract

The synergistic effect of mixing ethylene with propane on the nanostructure and morphology evolution of soot in laminar coflow diffusion flames was investigated via combining thermophoresis sampling and transmission electron microscopy (TEM). A strong synergistic effect was observed regarding the soot yields when 0.05 and 0.1 propane ratios were applied. However, it was inhibited at 0.2 propane ratio. At the height above burner (HAB) of 20 mm, the soot size generated from pure ethylene flame was larger than other mixed fuel flames. At the lower and higher HABs, the addition of propane could increase the mean primary soot diameter in different degrees. The high-resolution transmission electron microscopy (HRTEM) analysis showed that the propane addition resulted in larger fringe length, smaller fringe tortuosity, and spacing at 0.1 and 0.2 propane ratios—especially at 0.2 ratio—indicating the soot have a more compact structure and higher degree of graphitization.