Effects of gas temperature and oxygen concentration on the soot formation of laminar diffusion flames in the ambient gas mixtures of carbon-dioxide and oxygen

Abstract

Effects of gas temperature and oxygen concentration on the soot formation of the axial jet laminar diffusion flame have been studied experimentally for the ambient gas mixtures of carbon-dioxide and oxygen. These data were compared to those for the ambient gas mixture of nitrogen and oxygen of 21%. The experiments showed that the flame heights for the mixture of carbon-dioxide and oxygen of 21% and that of nitrogen and oxygen 21% were about same and decreased with the increase of gas temperature. When the oxygen concentration was 21% in the ambient gas mixtures, the total soot volume for the ambient gas of nitrogen and oxygen were higher than that of carbon-dioxide and oxygen and increased with the increase of the gas temperature. When the ambient gases were the carbon-dioxide and oxygen mixtures, the total soot volume increased with the gas temperature for the fixed values of the oxygen concentration in the ambient gases. But, for the fixed ambient gas temperatures, the total soot volume increased with the increase of the oxygen concentration in the ambient gas and reached to a maximum, and then decreased slightly with the increase of the oxygen concentration. The variations of total soot volume were discussed by using the adiabatic flame temperatures for the experimental conditions. The plots of logarithm of the total soot volume for the inverse value of the adiabatic flame temperature show that the oxygen concentration has the strong effect on the total soot volume compared to the effect of the adiabatic flame temperature.