Effect of freeboard deflectors on the temperature distribution in packed beds

Freeboard deflectors have been applied in solid fuel combustors but little investigation has been undertaken to understand their impact on packed beds. This paper studies the influence of a deflector above a packed bed by implementation of a three-dimensional Computational Fluid Dynamics (CFD) model of a porous media. Through validating the model against experimental data, the effects of a freeboard deflector on the radial and axial temperature profiles is studied for a temperature range typical for drying and volatile release in biomass combustion (100-400 °C). Numerical results indicate that the deflector influences wall temperatures as well as temperatures along the freeboard but this is dependent on the mode of heating and emissivity of the deflector.