Analytical study of transient counter-flow non-premixed combustion of biomass in presence of thermal radiation

Abstract

Abstract In this study, the transient behavior of a counter-flow non-premixed combustion of dry biomass particles under thermal radiation was modeled analytically. Unsteady conservation equations for mass and energy transports are mathematically formulated in dimensional and dimensionless forms. Preheating, vaporization and reaction processes were considered as the main processes for combustion of the biomass particles. The derived analytical model was solved using an asymptotic technique. After validating our derived analytical model with experimental data, the counter-flow non-premixed combustion of dry lycopodium particles with air was investigated. First, the temporal evolutions of distributions of temperature and species mass fractions were presented and discussed. Also, the temporal changes of flame temperature and position were discussed. The influence of thermal radiation was found to be quantitatively other than qualitatively. Finally, the effects of key operating parameters, such as biomass particle diameter, and Lewis numbers of biomass and oxidizer, were studied. When the combustion process reaches steady state, for unity Lewis number, maximum values of flame temperature with and without the radiative heat losses are equal to 1650 K and 1910 K at t = 0.02 s , respectively.