Chemical kinetics modelling for the effect of chimney on diffusion flame in carbon nanotubes synthesis

Abstract

Hydrocarbon flame syntheses of carbon nanotubes (CNTs) on various metals substrates have been reported in literature, but existing methods are limited to usage of high melting temperature metals substrate due to excessive temperature in conventional diffusion flame burner. To address this limitation, high thermal conductivity chimney is innovatively incorporated into the diffusion burner to control flame temperature. Hence, the aim of this study is to investigate the effect of chimney application on the interaction behaviour between flame temperature profile and concentration of post combustion species distribution of diffusion flame. In this study, Computational Fluids Dynamics (CFD) – Chemical Kinetics (Chemkin) coupling method is used to simulate the flow and transport behaviour of laminar methane-air mixture in combustion environment. Kinetics mechanism is imported into species transport model of Chemkin simulator to further determine the reaction between combustion species and temperature profile of the mixture. Heat transfer models are then integrated into simulation to investigate the cooling effect of chimney during the combustion of methane-air mixture. This numerical simulation study provides insights on effects of chimney application towards cooling, species concentration, flame temperature and paving path for controlling the growth of CNT on low melting temperature metal substrate. Numerical models show improvement in temperature controls, increase in gas species concentration and in surface area that is favourable for growth of CNTs.