Effects of Oxygenated Fuel on Soot Particle Formation in a Diesel Spray Flame

Oxygenated fuels with different oxygen content and molecular structure were used, and effects of oxygenated fuel on soot volume fraction and soot particle sizes were investigated by Time-Resolved LII (Laser induced incandescence) in a diesel spray flame. Soot particle formation was measured in a constant volume combustion vessel that was able to simulate the diesel engine conditions. Fuels used in this study were n-heptane, four ethers that contain (-O-) bond in molecular structure ; Dibuthyl ether (DBE), Diethylene glycol dibuthyl ether (DGB), Diethylene glycol diethyl ether (DGE), Diethylene glycol dimethyl ether (DGM), two esters that contain (-COO-) bond ; Buthyl acetate (BA), Ethyl acetate (EA). Oxygen content in oxygenated fuel changes from 12.3 wt-% to 36.4 wt-%. Soot volume fraction decreases in proportion to oxygen content in same molecular structured oxgenated fuel. Ether is more effective than ester in reducing soot volume fraction and suppressing the growth of soot particle diameter. And, by the application of oxygenated fuel, though soot volume fraction decreases, small soot particles are formed with high number density.