Soot generation of diesel fuels with substantial amounts of oxygen-bearing compounds added

Two-colour pyrometry, thermodynamic analysis, and exhaust emissions analysis have been used to improve understanding of the formation of soot during combustion in a high speed direct-injection automotive diesel engine. Three fuel blends were used: a Base Fuel commercially available in Northern Europe; a blend of the Base Fuel (70%) and esterified rape-seed oil (RME) (30%) and a blend of the Base Fuel (90%) and an ether compound (diglyme) (10%). While the Base Fuel contained no oxygen, both the other two fuels contained equal amounts of oxygen of 3% by mass. The principal results show significant differences in soot generation during combustion between the two oxygenated fuel blends, despite both having the same amount of oxygen.