Radiation Characteristics of Corrugated Cardboard Flames

Abstract

The relation between flame radiation, smoke yield, and smoke point of a practical solid fuel, namely corrugated cardboard, is studied experimentally. Experiments are performed using an ASTM E 2058/ISO 12136 Fire Propagation Apparatus (FPA). Corrugated cardboard flames are established in the FPA under external heat fluxes representative of those found in a large-scale fire scenario. The heat release rates for these flames are on the order of 7 to 10 kW based on calorimetry analyses. Radiation is measured using a heat flux gage located in the near field of the flame. In order to better interpret calorimetry data, effort is placed on the characterization of the chemical composition and thermodynamics of the corrugated cardboard used both in its virgin and charred states. A novel smoke point measurement system based on the FPA is also described and demonstrated. It is shown that the specific heat of combustion of volatiles released from the pyrolysis process increases with pyrolysis progress. Furthermore, flame radiant fraction, smoke point, and smoke yield are also shown to vary during pyrolysis and combustion. The variations of both the smoke point and radiant fraction with pyrolysis progress at different heating rates indicate that the volatile chemical composition continuously varies during pyrolysis. These observations are explained by faster release rates of fuel oxygen and hydrogen than that of carbon during pyrolysis.