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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
Refillable butane lighters have been around for quite a while, I'd imagine this technology would have a similar refueling mechanism.
Will these devices come with ear plugs or noise blocking head phones?
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.
This is a gas turbine: flow of gas turns the rotor. The similar thing that is used in dams to generate electricity. It is not a machine that burns the gas so it is has nothing to do with carnot cycle.
A gas turbine is a heat engine and is limited by Carnot efficiency. However, the machine described as being 95% efficient in the BBC article is not a gas turbine. It's a generator.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
It would be pretty cool to run a laptop for hours on a gas engine, but will I be allowed to take it with me when I fly? I can't imagine that TSA is going to allow me a small quantity of flamible liquid so I can run my laptop on the plane. What about the emissions in a closed environment?