Large-Scale Field Experiments on Enhancing In-Situ Burning with Fire Whirls.

Fire whirls, a combustion-intensifying phenomenon, offer potential for cleaner, more efficient burns with reduced emissions in environmental applications like oil spill remediation. While most knowledge of fire whirls stems from laboratory-scale experiments, and only a limited subset of these experiments has captured emissions, this study addresses a critical research gap by conducting one of the largest controlled fire whirl experiments to date, focusing on enhancing in-situ burning. Using a 1.5-meter diameter crude oil pool with 15 mm and 40 mm slick thicknesses on an open water surface, fire whirls were successfully generated within a 5-meter-tall three-wall structure under the influence of various wind conditions. Measurements of flame geometry, flow velocity, temperature profiles, heat flux, mass consumption, and emissions were compared to pool fires. Results revealed that fire whirls, with mean flame heights nearly double those of pool fires, increased burning rates by 40% and reduced soot emissions by 40%. The highest fuel consumption efficiency of 95% was achieved in a 15 mm slick thickness fire whirl experiment, while in other fire whirl experiments, especially those with 40 mm slick thickness, premature extinguishment was observed lowering ultimate fuel consumption efficiencies. Enhanced performance compared to traditional pool fires suggests that fire whirls might be more effective for in-situ burning, however this efficiency is currently only achieved under calm ambient conditions. This study discusses the potential interactive effects of ambient conditions, configuration sizing, and boilover phenomenon on fire whirl dynamics, highlighting the need of continued research across scales to optimize configurations and mitigate detrimental emissions, thereby enhancing the efficacy of in-situ burning in large-scale oil spill scenarios.