Cool-Burning Flames in Space May Lead to Cleaner Engines in Cars (VIDEO)

A team of scientists on the International Space Station have made a surprising discovery. They've found a new type of cool burning flames that could lead to cleaner and more efficient engines for cars in the future.

When engines burn fuel, they usually burn it at higher temperatures. This results in emissions of pollutants, such as soot, nitric oxide and nitrogen dioxide. Yet these latest findings reveal that fuel could potentially be burned at lower temperatures and thus emit fewer pollutants.

During the course of their experiments, researchers ignited large droplets of heptane fuel. While at first it appeared as if the flames extinguished themselves, closer inspection showed that the heptane was still burning. These cool flames, though, were invisible to the naked eye.

The scientists found that these cool flames could occur in a wide range of environments, including air similar to the Earth's atmosphere and atmospheres diluted with nitrogen, carbon dioxide and helium. The resulting combustion reaction creates toxic products which then burn off.

So why did these cool flames occur on the space station? It all has to do with buoyancy. When droplets burn on Earth, buoyancy limits the amount of time gases can hang around in the high temperature zone around the droplets. This means that there isn't enough time for the droplets' chemistry to support the cool flames. In micro-gravity, though, there's no buoyancy so there's enough time for the gases to stay around the droplets and for the chemistry to develop.

The current challenge is to get the right mix of fuels to generate cool flame combustion on Earth. NASA actually is planning a new series of experiments starting next week in order to potentially address this challenge.

The findings could potentially help reduce the amount of pollution in the future. If scientists can successfully create cold flames on Earth, the process could be used in a variety of applications.

The findings are published in the journal Microgravity Science and Technology.

Want to learn more? Check out the video below, courtesy of YouTube.