Upward and Downward Smoldering in RDF (Reduced-Derived Fuel) Layer

Abstract

The effect of direction of spread, natural convection, sample size, void fraction, etc. on fire spread in the piled RDF (RDF fixed bed) was examined experimentally. RDF samples were produced cylindrically from general domestic garbage, and different size of sample ; 15.5 mm (D) × 37.1 mm (L) and 28.6 mm (D) × 50.5 mm (L) were used. Temperature change, temperature profile and spread rate of fire in the layer were measured. As a result of the experiment, when the bottom side in the layer is closed, the downward fire spreads faster than that of upward. And also, the fire spreads faster in the case of bottom side opened than it in the case of bottom side closed. It is found that the spread rate of smoldering increases with sample size or void fraction in natural convection. Though it is adiabatic for large void fraction in RDF layer, the smoldering continues by inflow air to the clearance. The effective thermal conductivity of powder packed bed was applied in RDF layer, and the effect of sample size, shape, void fraction, inflow air velocity on the fire spread was evaluated.