Soot particles diagnostics in ethylene inverse diffusion flame blending with biodiesel surrogates of saturated methyl butyrate and unsaturated methyl crotonate

Comparison research on the flame temperature, soot productions, the morphology, the nanostructure and the oxidation reactivity of the soot particles sampled from ethylene inverse diffusion flames with blending biodiesel surrogates of saturated methyl butyrate (MB) and unsaturated methyl crotonate (MC) were carried out. The flame temperature was measured by a thermocouple, soot morphology and nanostructures were investigated by using Transmission Electron Microscopy (TEM) and High Resolution TEM, the graphitization and oxidation reactivity were analyzed by X-ray Diffraction and Thermogravimetric Analyzer. Effects of blending rate of biodiesel surrogates of MB and MC were discussed. The results show that, with the increasing of MB additions, the flame temperatures is lifted, soot production increases firstly and then decreases because of a comprehensive effect depending on the oxygen content from oxygenated saturated MB. With MC blending, the flame temperature declines, but the soot production jumps approximately double due to the synergistic effect of C=C double bonds and oxygen functional groups in oxygenated unsaturated MC. Because of oxygen components in MB and MC, soot particles sampled from MB and MC blending flames have been oxidized to be more mature with larger fringe length, bigger fringe tortuosity, higher graphitization degrees and lower oxidation reactivity.