Sooting Tendency of Fuels Containing Polycyclic Aromatics in a Research Combustor

Abstract

Several jet fuel blends containing alkyl benzenes, methyl naphthalenes, tetralin, and indene were prepared with hydrogen contents ranging from 11.5 to 14.2%. The effects of burner inlet conditions on the sooting tendency of the test fuels were measured in a Phillips 5.08-cm (2-in.) diameter cylindrical combustor at inlet pressures and temperatures up to 1620 kPa (16 atm) and 1100 K, respectively. Both flame radiation and opacity measurements were used to determine the soot formed in the primary zone of the burner. Combustion efficiency and fuel/air ratio were determined from gaseous emissions. The sensitivity of the sooting tendency to the H/C ratio was determined from the correlation of flame radiation intensity with the H/C ratio. This sensitivity varied significantly with operating parameters such as burner inlet temperature and reference velocity. The effects of polycyclic aromatics were determined by comparing the sensitivity to the H/C ratio of fuels blended by adding methyl naphthalenes and tetralin with that of fuels blended by adding alkyl benzenes. The increased sooting tendency of those fuels containing polycyclic aromatics was most affected by the fuel/air ratio and reference velocity. Nomenclature F/A = fuel/air weight ratio H/C = hydrogen/carbon atom ratio R = flame radiation intensity, kW/m2 S = normalized sensitivity of sooting tendency to the H/C ratio 57V = smoke number T = burner inlet temperature, K V = reference velocity, m/s p = gas density, kg/m3