PAHs Formation Behavior in Laminar Diffusion Flames of Paraffin Fuels

Abstract

Nano meter size particulate matter (PM) and polycyclic aromatic hydrocarbons (PAHs) have harmful effects for human health. Investigations of fundamental characteristic of formation behavior of PAHs in combustion process were required for the reduction of nano-PM emission. In this paper, PAHs characteristics in diffusion flames of paraffin fuels were investigated using laser diagnostic and gas sampling methods. Methane (CH4), propane (C3H8) and hexane (C6H14) were used as the test fuels. A laser induced fluorescence (LIF) method was used to obtain the spatial distributions of PAHs which were precursor molecules of soot. Spatial distributions of soot were also measured by a laser induced incandescence (LII) method. A transition region from PAHs to soot was defined from the results of LIF and LII. Further, PAH concentrations in the test flames were measured using a gas chromatography (GC).Profiles of PAHs concentrations of test flames were compared. As the results, it was found that the low carbon number fuels such as propane and methane are remained to some fuel at downstream part. And, these some fuels were changed to large PAHs at downstream part.