Fuel Composition and Molecular Structure Effects on Soot Formation in Direct-Injection Flames Under Diesel Engine Conditions
Numerous investigations have been conducted to determine the effect of fuel composition and molecular structure on particulate emissions using exhaust gas analysis, but relatively few measurements have been obtained in-cylinder or under conditions where fuel effects can be isolated from other variables. Recent work has shown that the amount of air entrained upstream of the lift-off length is critical to soot formation and therefore must be controlled when making relative comparisons of soot formed from various fuels. In this work, dimethoxymethane was used as the base fuel to produce a non-sooting flame with relatively constant lift-off length in a constant volume combustion vessel at 1000 K, and a density of 16.6 kg/m3. A second fuel was then mixed into the dimethoxymethane (DMM) to determine a point at which soot formation begins.