Study of soot formations in co-flow laminar diffusion flames of n-heptane and oxygenated aromatic biofuels from atmospheric condition to 2.3 bar

Anisole and benzyl alcohol, both are lignin based oxygenated aromatic biofuels as a pair of isomers with benzene rings possessing different oxygen functional groups. This work investigated the characteristics of soot formation in laminar co-flow diffusion flames with n-heptane and its blends with anisole and benzyl alcohol from atmospheric to elevated pressures. With the high-pressure burner and pressurized Twin-Lines liquid fuel evaporization (TLLFE) system, a series of experiments were carried out to measure the sooting tendency by utilizing the Laser induced incandescence (LII) combining with Line-of-sight attenuation (LOSA) technique. The experimental results show that with the addition of anisole and benzyl alcohol, the soot formation in flames is enhanced, especially for the addition of benzyl alcohol. Moreover, the elevated pressure can enhance the soot formation in n-heptane and n-heptane/anisole flames, and the integrated soot volume fractions (SVFs) follow power law relationships with pressure. The power dependence on pressure for n-heptane/anisole flame is larger in comparison with that of n-heptane flame. These findings provide basic understanding of the soot formation in co-flow laminar diffusion flames of n-heptane and oxygenated aromatic biofuels.