Researchers at Tohoku University have developed a working prototype of what they are calling the world's smallest gas turbine engine, a palm-sized motor they hope will one day be used to power autonomous robots and serve as a portable engine for personal transportation devices.
The research team led by professor Shuji Tanaka from Tohoku University's Nano-Precision Mechanical Fabrication Lab worked with researchers from IHI Corporation and the University of Tokyo to create the tiny engine, which measures 10 cm (4 in.) in diameter and 15 cm (6 in.) in length. With a 16 mm (0.63 in.) compressor rotor diameter and a 17 mm (0.67 in.) turbine rotor diameter and combustion chamber, the engine boasts a rotational speed of 500,000 to 600,000 rpm, which is made possible by special air bearings the researchers developed.
Unlike battery-powered engines that need to stop for periodic recharging, gas turbine engines can run continuously as long as fuel is supplied. Furthermore, gas turbine engines feature a higher power density than fuel cell and battery-powered engines, and they run cleaner than reciprocating piston engines.
With demand expected to increase for robots that use commonly available fuels and compact motors for personal transportation for the elderly, the Tohoku University researchers have been working with IHI since 2000 to develop a portable, lightweight and quiet engine able to operate for long periods of time between refuelings. After 7 years of work, they have broken the 20 mm diameter rotor barrier, a goal long shared by their microturbine-minded peers around the globe.
The engine has not yet been outfitted with a generator because it is still under development, but space has been set aside for it within the engine.
The engine will be officially unveiled at PowerMEMS 2007 scheduled for November 28-29 in Freiberg, Germany.
[Source: Nikkei Net]
RC
1) Not even close to the world's smallest. That honor probably belongs to MIT's tiny turbine: http://web.mit.edu/newsoffice/2006/microengines.html
2) WTF are "battery-powered" engines? Do you perhaps mean electric motors, powered by batteries?
3) Electric motors can be powered for as long as "fuel" is supplied, but few tasks are important enough to necessitate hot-swappable batteries. In fact they can run indefinitely, unlike turbines, which need to be taken off-line for periodic maintenance.
4) Turbines being "cleaner than reciprocating piston engines" is not necessarily true. Turbo diesel engines can get very high efficiency. Turbines hold the record, but that's not necessarily the case across the range of possible form factors, fuels, and operating conditions.
5) There is no such thing as turbine or fuel cell "power density." It makes no sense. Fuels, not engines, have properties of power density. Hydrogen is less dense than any other fuel (in fact any form of matter), but fuel cells can run on fuels other than hydrogen. More than that, power density isn't an important metric at all, for any purpose.
[]mjag17
The microturbine project team at MIT doesn't have a working prototype yet... Although on the note of smallest, I do remember another tiny turbine by a swiss team I think, and another by M-Dot? can't remember the details but both seemed to fit in the palm of one's hand.
[]Brian Coffey
This is very cool - I can't wait for continued development of these small turbines. I want to use a ~10 kW model as an auxiliary power unit in a series hybrid, but it seems like this order of magnitude has been skipped in favor of more impressive miniaturization.
@RC: There actually is such a thing as power density, and it turns out to be an especially important metric in weight sensitive applications. A thing's power density is its output (say, in Watts) divided by its mass (say, in kg). You may be surprised to learn that it makes no sense to speak of a fuel's power density, since a fuel by itself doesn't make any power. A few minutes on wikipedia could go a long way toward futhering your understanding of energy and power.
Brian Coffey
[]Vehicle Design Summit
Hello Moto
RC, I agree with you on several of your points, but the last one is not correct. Engines do have a 'power density' which refers to the power (rated in HP or watts) that the engine can produce at a given weight. Gas-turbines have generally been known to have a higher power density the other engines such as the ICE you find your car.
If ICE had better power densities than turbines then they would still be on most airplanes.
One thing about gas turbines: These engines have a limited range of power and a very high use of fuel during idle. As such they could be very useful for hybrid type designs but for sticking in something like a wheelchair would be very bad as they would constantly have to start and stop or waste a lot of fuel idling.
Ah - last thing: I don't know the exact size but RC jet engines have recently become available which are gas-turbines and they don't look much larger than this, are you sure it’s a world record or did the company just assume it was like all the electronic companies do (such as when they say "world's largest screen!" even though their competitor released on several inches larger the week before...
[]Ron van Sommeren
@Brian
http://www.amtjets.com -> specifications
There are several manufacturers, see
http://www.airtoi.com -> jets
or check out this forum, pulsejets and turbines:
http://www.pulse-jets.com/
Ron van Sommeren
[]near Nijmegen, the Netherlands
j3mm@
thats tiny lol x0x
[]nhoj
How did the unvieling go at PowerMEMs 2007? How about posting a youtube of the thing running, and by all means get this thing to produce some electricity. One more thing, could you publish details on horsepower, heat produced, fuel type, and fuel consumption rate at max rpm? Those details should not divulge your research I wouldnt think.
Thanks in advance,
[]j
Todd LLoyd
If this is the "Worlds Smallest..." could you share your source. Is it in the Guinness Book Of World Records or something?
Regards,
[]Todd Lloyd
http://portablegeneratorinformation.com
Peter Palmer
The great thing about it is the rotor for the generator is already in the box. Should be pretty cheap building the whole thing (compared to other turbines of that size that is). But...
Did I remember right that these things get pretty hot? Wasn't there a problem with static magnets and high temperature? How is that solved?
Where does the combustion chamber go again?
That sounds like I can generate 2kW in less space than the alternator of my car? I am not surprised they still have to catch up on that part :o)
Promising though.
[]TC Williams
I want one of these. I am almost afraid to ask...how much? Is it even possible for one to be sold to me? Serious inquiry!
[]pankaj patil
hi sir,
i m doin my msc. in automotive. im very much interested in this concept to run a vehicle with the help of gas tubine. i had read much about it but i know it is nothing. iwant to know that what is difference between large stationary gas tubines and combustors small gas turbines used in automotive....
i will be very thank ful to u if u look in to my question.
i know some differences but due to practically inexpirence i cant understand properly.and smallest gas turbine is awesome.it makes me to think more about it.
with regards
pankaj patil
[]James Smith João Pessoa, Brazil
I have envisioned a very small gas turbine running at its most efficient speed turning a generator through a large reduction gearing. Modern generators such as for boats and RVs like to turn at 1800 RPM. So a small turbine running at 18,000 RPM or more and geared down to 1800, might have enough torque to efficiently run the generator.
Because the turbine could be computer-controlled to always turn at its optimum speed, it could also run on a variety of fuels, both liquid and vapor such as hydrogen, propane, methane, kerosene, alcohol, gasoline, or other. Being computer controlled, fuel flow could be easily adjusted to keep the turbine running at the correct speed no matter what the "energy density" of the fuel.
[]Matt
Microturbine generators don't use gearboxes to reduce the speed in order to run a generator of the sort that is used with reciprocating engines. Rather, they run the generator at the speed of the turbine, and use power electronics to to change the voltage and frequency (to, say, 60hz, 120VAC). In the case of this turbine, the generator appears to be integrated into the shaft between the turbine and compressor, which greatly reduces the size, weight, and overall complexity of the setup.
[]van samson
I want to help design the generator part of the mini-turbine. The heat of the turbine will affect the performance of the generator, but I think there are several ways of solving the problem. Most of all, my generator design will simplify the electrical and possible electronic circuits.
[]van samson
I forgot to add--I'm interested in possibly using the facilities of Tohohu Univ's Nano Precision Lab for my other brushless rotating ac and dc machines and for my new designs of miniature turbine engines.
[]Charlie
What exactly is the point in a battery powered engine? No sense is made! Distracting!
[]