AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Growth Mechanism of Soot in Recirculating Hydrocarbon Flames
KARTIK TIWARI, Justin Davis, Igor Novosselov, University of Washington
Abstract Number: 659 Working Group: Combustion
Abstract The effect of flow recirculation on the primary particle size and chemical composition of soot are studied in an Inverted Gravity Flame Reactor (IGFR) for methane-air diffusion flame. Although the mechanism for soot surface reactions, dimerization and coalescence are studied by several research groups; the transition of gas-phase species to liquid or solid particles is still not well-understood. Due to buoyancy force acting opposite to the inertial force, IGFR leads to longer residence times including recirculation of flow near the flame front. This provides a conducive environment for carbon soot growth producing large primary particle sizes (≈ 60 nm). The mass flow rates of methane and air are varied to achieve the desired residence time and flame structures. Soot formed in IGRF and upright flame under these conditions is analyzed using an electron microscope. The characterization of soot chemical composition is performed using gas chromatography/mass spectroscopy (GC/MS). Numerical simulations based on detailed methane chemistry and moment closure for soot particle population balance equation also confirmed higher primary particle size for IGFR. The comparison of in primary particle size distribution and their chemical composition for IGFR and upright flame provides a better understanding of soot growth mechanism.