Denmark may not be a big country, with only 5.6 million inhabitants, but there are more than 160,000 mopeds there, not to mention lawnmowers, chainsaws, and even cargo ships that transport goods. Each of these have a common thread: they all run on two-stroke engines. Michael Madsen and Jesper Rasmussen, both riders of mopeds, found out one day how utterly inefficient and polluting they could be, even for their size. The reason is that with two-stroke engines, no matter the size, when fuel is injected into the cylinder, part of it is allowed to escape through the exaust manifold (see white spheres in picture).
This means that not only are you sending a large portion of your fuel in the exhaust without burning it (30-40% on average in chainsaws), these hydrocarbons are released into the atmosphere as reactive organic gases, which cause a slew of health problems. Madsen and Rasmussen decided to design a system that would eliminate these problems and make the engine more efficient. What they’ve done is created a unique design in their exhaust system that pushes the overflowing hydrocarbons, along with a little of the exhaust, back into the cylinder by way of a shockwave traveling at 500m/s.
This allows the fuel to be completely burned, and has resulted in a fuel efficiency improvement of 17.7%, just for their mopeds. Carbon monoxide has been decreased by 10% and hydrocarbon emissions have been reduced by 36.7%. The system is even more efficient in hot, dry climates, so would work well in areas like California, many countries in Asia, and the middle east. Heavy cargo ships, carrying some of the most polluting engines in the world, would greatly benefit from this technology, and the team has patented their system and hopes to bring this to market in the future.
Frankly, it makes us at EcoGeek feel like we're slacking. If this is what high school students are doing, shouldn't we be doing a bit more than just blogging?
written by Advent, May 16, 2008
written by Jordan Lyons, May 16, 2008
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