Publications

Mass-loss measurements on solid materials after pulsed radiant heating at high heat flux

Engerer, Jeffrey D.; Brown, Alexander B.; Christian, Joshua M.

When exposed to a strong radiant heat source (>1,000 kW/m2), combustible materials pyrolyze and ignite under certain conditions. Studies of this nature are scarce, yet important for some applications. Pyrolysis models derived at lower flux conditions do not necessarily extrapolate well to high-heat-flux conditions. The material response is determined by a complex interplay of thermal and chemical transport phenomena, which are often difficult to model. To obtain model validation data at high-heat-flux conditions (up to 2500 kW/m2), experiments on a variety of organic and engineered materials were performed at the National Solar Thermal Test Facility at Sandia National Laboratories. Mass loss during the short duration (2-4 sec) heat pulse was determined using the pre- and post-test weight. The mass-loss data were fairly linear in the fluence range of 200-6000 kJ/m2. When divided into subsets based on material types, the mass loss was similar at the peak flux/fluence condition for engineered polymers (≈1 g) and organic materials (≈2.5 g), although some exceptions exist (PMMA, dry pine needles). Statistical correlations were generated and used to evaluate the significance of the observed trends. These results contribute to the validation data for simulating fires and ignition resulting from very high incident heat flux.