Scientists have discovered a fire tornado that could help produce clean energy.
Researchers at the University of Maryland (UMD) A. James Clark School of Engineering have found a type of fire tornado called "blue whirl," which burns almost soot-free.
"Blue whirls evolve from traditional yellow fire whirls. The yellow color is due to radiating soot particles, which form when there is not enough oxygen to burn the fuel completely," Elaine Oran of the professor of engineering at Glenn L. Martin Institute and co-author of the study, said in a report by Phys.org.
"Blue in the whirl indicates there is enough oxygen for complete combustion, which means less or no soot, and is therefore a cleaner burn."
Fire tornadoes or fire whirls are natural phenomena that are considered catastrophically dangerous, especially in urban and wildland fires. But the newly discovered blue whirl could be a friend to mankind, as it could be able to produce energy without pollutants and at the same time, it could also be a tool to clean up oil spills.
Researchers were initially investigating fire whirls that burn over water as an effort to improve oil spill clean up when they discovered the blue whirl. To make a flame, the researchers poured liquid fuel on the surface of the water in a steel pan, which is ignited to form what researchers called a pool of fire. The flame could burn on any fuel-smeared flat surface, such as oil spills, and grow into fire whirls.
From a fire whirl, the fire turned into a blue whirl, which is smaller, more stable and burns "completely blue as a hydrocarbon flame," which indicates soot-free burning.
"The combination of fast mixing, intense swirl, and the water-surface boundary creates the conditions leading to nearly soot-free combustion," the researchers wrote in the paper, which was published in Proceedings of the National Academy of Sciences.
The yellow color in most flames comes from soot particles, which means that there is not enough oxygen to burn the fuel completely. However, the blue whirl's color indicates that it contains enough oxygen to efficiently and completely combust without creating soot.
"Fire whirls are more efficient than other forms of combustion because they produce drastically increased heating to the surface of fuels, allowing them to burn faster and more completely. In our experiments over water, we've seen how the circulation fire whirls generate also helps to pull in fuels," Michael Gollner, assistant professor of fire protection engineering and co-author of the study, told Phys.org.
"If we can achieve a state akin to the blue whirl at larger scale, we can further reduce airborne emissions for a much cleaner means of spill cleanup."