New Device Burns Fuel With Almost Zero Emissions
by Justin Thomas, Virginia on 06.27.06
Researchers at Georgia Tech are showing-off what they say is a combustor with virtually no emissions of either nitrogen oxide or carbon monoxide — two main contributors to air pollution. Their design, which is modeled around an aircraft turbine engine, as opposed to the piston-driven combustion engine that's found in most cars, relies on a new and unique fuel delivery system. In current turbine combustors, fuel and air are usually premixed prior to it being injected into the combustion chamber. While the process helps to reduce emissions, the process is complex, expensive and difficult to control, say the Georgia Tech scientists who've taken a different approach.
In the Georgia Tech engine, called the Stagnation Point Reverse Flow Combustor, the fuel and air aren't premixed. "We inject the fuel and air directly in the combustion chamber and they premix together before they ignite," says Dr. Ben Zinn, one of the project's key collaborators. The result is improved control of the combustion process and substantially-reduced emissions.
Dr. Zinn explained that in current combustors, the fuel/air mix ignites immediately upon injection, and burns at a very high temperature. It's this high temperature flame that results in high levels of nitrogen oxide emissions that contribute to smog. Unique to the new design is the fact that the fuel enters into the combustor on the same plane as it exits. In other combustors, the fuel is injected into one end of the combustion chamber, is burned, and the exhaust exits out the other. Not so in the Georgia Tech design, where the fuel-air mixture is injected and swings around the bottom of the combustor, burns, and then is exhaust out the same end it entered.
:: Via Discovery Online
Actually, these kinds of "reactors" have been available for purchase for quite a while- see for example http://www.woodgas.com/woodgasstoves.htm
I would comment that Turbine engines have long been more fuel efficient than combustion engines; however, the reason they aren't used in automobiles is that they have a very low torque capacity. In other words, when you push on the gas of a turbine powered car, you would creep, not jump, from the starting line. Not such a good idea if you're trying to get out of the way of that on-coming train.
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editor note: Interesting. I suppose this means that a turbine engine coupled with electric motors (high torque from very low RPM) would be - in theory - a good match.
The idea of coupling the turbine engine with EV is a new one to me, but it only address the low-torque issue with turbine. I think the defuncted Rosen Motors had a flywheel design to address the low-torque issue back in the 90's. I don't know if turbine can be turn on or off like today's hybrids, and I am curious about the "warm-up" time required for optimal efficiency. Of course, while it may not save fuel when the vehicle is at idle, the efficiency may offset the loss.
The other issue is the temperature. I think most drivers of turbine prototypes say the interior is relatively quiet, but it gets warm real quick. Lastly, I think safety could be an issue. With enough engineering, it will probably be safe enough, but in the end, it is the public who will need to be convinced that it's safe enough to be on the road. I've seen enough movies to easily imagine turbine blades flying about, during a crash.
I suggest that steam power be considered as a proven and practical means of using any external combustion heat source for power. The members of the Steam Automobile Club of America have been working on modern steam power development. It has reached the point of theoretical practicality.