A Study on Soot Formation Characteristics of a Gasoline Surrogate Fuel Using a Shock Tube

Soot formation characteristics of gasoline surrogate fuels have been studied using a shock tube. Soot yield from thermal decomposition of mixed hydrocarbons including a gasoline surrogate fuel was obtained from measured soot volume fraction by the laser extinction method. The soot particle temperature was estimated based on spectral dependence of monochromatic emissive power of thermal radiation from the soot particles. The gasoline surrogate fuel used in the present work was basically composed of five hydrocarbons (isopentane, n-heptane, isooctane, toluene, 1,2,4-trimethylbenzene), and its composition was determined to emulate the distillation characteristic of a commercial gasoline fuel. In addition, a binary-, three- and four-component hydrocarbon fuels were tested for comparison. The shock tube tests were conducted at various temperatures ranging from 1700 to 2400 K and at a pressure of 200–260 kPa. The experimental results show that decrease in aromatic hydrocarbon in the fuel leads to less soot yield and delay of soot formation. The temperature at which maximum soot yield for the gasoline surrogate fuel is obtained is shifted to higher temperature as compared to the binary fuels containing 50% isooctane and 50% toluene.