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Two Tiny Gas Turbines
Turbines are in the news this morning. bobtheimpossible writes to point out a BBC article on a Swiss turbine that runs at half a million RPM and generates 100 watts. It's the size of a matchbook. And af_robot alerts us to an even more diminuitive gas turbine on a chip, developed at MIT, that generates 10 watts — plenty for portable electronics — and should run 10 times as long as a battery of comparable weight and cost. A commercial version is 3 to 5 years away.
It's still a mecanical conversion of a compounds to energy, with all the inefficiencies that go with it, including disposal of waste heat. Where's these fuel cells I keep hearing about?
10 props for neat, anyway.
also, can it do this?
A feeling of having made the same mistake before: Deja Foobar
Two postings now and the obvious question is still not answered... where the hell are you supposed to get the fuel for these things? How are they supposed to be refilled? Still nothing.
Imagine how tough it will be to bend over and tie your shoe with that thing on your hip. That could be a workout on it's own: The Gyroscopic Abdominzeratertron.
At 95% efficiency (a dubious claim, imho, given that the cold sink temp is presumably room temp), it would be a good source for constant charging and potential peaking current. You'd need a good number, though, at roughly 8 to the horsepower.
I think the future might be in portable power and backup devices - having a refillable, continuous 7-15kW power supply in a breadbox. With the right gear ratios, it could put out sinusoidal 60hz power for AC backup, though synchronizing the signals and preventing drift across the array would be a task in itself.
Is it just my observation, or are there way too many stupid people in the world?
Probably not very much. In the picture, you can see the rotor is about the size of a match and probably weighs less than a gram. This means that its moment of inertia isn't all that large (moment of inertia goes like radius squared, in this case, r is on the order of 10^-3 m). Even at 500,000 rpm, the amount of kinetic energy stored in the rotor probably isn't large enough to be a major concern. The relative bulk of the stator probably would be enough to contain it, should it catastrophically fail.
The same is true of the gyroscopic motion - the reactive force is a function of the applied force and the angular momentum. If the moment of inertia of the rotor is very small, the reactant force is likewise small.
Also keep in mind that this device has a designed power output of 100 W, which is at least one, if not two, orders of magnitude greater than what you'd need for an mp3 player.
Sorry, but bollocks it is. A gas turbine is a heat engine, the efficiency is determined by difference between the temperature at combustion and the exhaust gases. 50% would be excellent for a gas turbine.
Deleted
I read the internet for the articles.
The best large gas turbines do about 35%.
And efficiency drops very quickly with size-- you see friction goes down as the square of the size, while power goes down as the cube. Somewhere between the size of a sausage and a hot dog, all the turbine power is going into overcoming friction.
And the biz about 1 million RPM is pure hokum-- the worlds record is a bit below that, and that was with a tungsten alloy rotor in a vacuum chamber.
Methinks some press agent was drinking while on duty.