Cool-Burning Flames in Space to Spark Better Engines on Earth [VIDEO]

In a series of trials aboard the International Space Station (ISS), researchers discovered a new type of cool burning flames that could lead to cleaner, more efficient engines for cars here on Earth, they reported in a new study.

"This technology is not currently available in cars. But it could potentially lead to engines that burn fuel at cooler temperatures, emitting fewer pollutants such as soot and nitric oxide and nitrogen dioxide, while still being efficient," the authors wrote on their website.

A better understanding of the cool flames' chemistry could help improve internal combustion engines in cars.

Led by Forman Williams, a professor of mechanical and aerospace engineering at the University of California, San Diego, researchers ignited large droplets of heptane fuel. At first, they thought that the flames had simply extinguished themselves, like they would have on Earth.

"But sensors showed that the heptane was still burning, although the resulting cool flames were invisible to the naked eye," the scientists said.

These cool flames occurred in a wide range of environments, including air similar to Earth's atmosphere and atmospheres diluted with nitrogen, carbon dioxide and helium. The resulting combustion reaction creates toxic products, such as carbon monoxide and formaldehyde, which in turn burn off.

The ISS team believes that these cool burning flames are the result of chemical reactions which make them able to exist on Earth for only a short period of time.

Buoyancy is what makes these flames able to hang around for longer duration in space compared to Earth.

"When droplets of fuel burn on Earth, buoyancy limits the amount of time gases can hang around in the high temperature zone around the droplets. So there isn't enough time for the droplets' chemistry to support the cool flames. But in micro-gravity, there is no buoyancy, so there is enough time for the gases to stay around the droplets and for that chemistry to develop," the researchers explained.

NASA plans to conduct a new series of experiments, not-so-cleverly titled "Cool Flame Investigation," starting next winter and continuing for a year's time, to figure out how to get the right mix of fuels to generate this cool flame combustion here on Earth. However, this research can only be done on the ISS where scientists have access to a microgravity environment that provides a sufficient amount of test time for cool flames to occur.

Researchers detailed their findings last month in the journal Microgravity Science and Technology.