Analytical modeling of counterflow non-premixed organic particles combustion: Thermal radiation effects

Abstract Controllability, safety and stability are benefits of diffusion flames which make them highly advantageous to be used in medical and power generation industries. Radiation heat transfer is a dominant phenomenon in flame propagation through organic particle clouds. In this research, a promising thermal radiative model is presented for non-premixed counterflow combustion (diffusion flame) propagating through volatile organic particles using an asymptotic method. In order to propose a credible model to analyze the flame, a multi-zone flame structure comprised of pre-heat, post-vaporization and post-flame zones, is considered. In addition, vaporization and reaction zones are supposed to have thin asymptotic fronts. Lycopodium particles and air are taken as biofuel and oxidizer, respectively. To follow the influences of dimensionless numbers, such as fuel and oxidizer Lewis numbers on the flame structure, dimensionless and non- dimensionless equations of mass and energy conservation are extracted for each zone. So as to observe the thermal radiation effects, a special term is added to the energy conservation equation. The governing equations are solved applying elaborate boundary and jump conditions. Eventually, variations of flame temperature, gaseous fuel and oxidizer mass fractions with respect to fuel and oxidizer Lewis numbers, mass particle concentration, particle radius and equivalence ratio are investigated considering thermal radiation and compared to those in which thermal radiation heat transfer is not considered. As a result, by applying radiation term in the left side of the flame zone, temperature increases and flame position moves toward the fuel nozzle. Moreover, considering thermal radiation increases the amount of produced gaseous fuel in pre-heat and post-vaporization zones.