Hydrogen Micro Turbine Only 4mm In Diameter 353
savaget writes: "Luc G. Frchette of the Columbia University Microsystem Engineering Laboratory has developed a 20W electrical generator powered by a hydrogen turbine just 4mm in diameter. For more details, read the Wired
article or an older Popular Science
article. The tiny generator is more efficient than any battery and is expected to find military and commercial uses including robotics." Imagine the uses ...
2.4 million RPM (Score:5, Funny)
That's 40 KHz.
Your dog is going to go totally nuts every time you turn on your PDA.
--Blair
How'd you figure that out? (Score:2, Interesting)
Re:How'd you figure that out? (Score:2, Informative)
2.4million revolutions per minute
Divide by 60 to get revolutions per second
revolutions per second is analogous to frequency(Hz)
Re:How'd you figure that out? (Score:2, Interesting)
Re:Holy shit! (Score:2, Funny)
2) There are 60 seconds in a minute
3) Hz is a measure of cycles per second
4) Simple arithmetic
If you knew those three things, you did know how to convert RPM to Hz. You were just to stupid to realize it."
Three things, huh? At least he knows how to count.
Re:Holy shit! (Score:2, Insightful)
No, one can also consult reference materials, but this requires initiative.
(And sometimes one wants to learn something that nobody else knows. This requires even more effort. Imagine the state of human knowledge if the only way to learn were to ask someone else.)
Re:How'd you figure that out? (Score:5, Informative)
(2.4E+06RPM (Rotations / Minute) / (60 Seconds / Minute) == 40000 Hertz
Or 40KHz
Re:How'd you figure that out? (Score:2)
Think of an orchestra. If 50 violins played the exact same note, does that mean that the frequency of the note is Note * 50? Nope. The amplitude of the sound waves just become greater. This is called volume.
Therefore, 12 blades on a fan spinning at 40kHz creates a noise 12 times as strong (roughly) as a single blade.
you, sir, are a pompous idiot. (Score:2)
If the fan were going to make 40Khz noise, that would indicate that there is a process which takes on the same configuration only once every revolution. This is not the case here; the system looks the same 12 times every revolution. So the sound produced is at 480 KHz.
Your orchestra example is also bogus. If you were to take the sound of a violin playing one note, and layer on 11 more copies of the same sound, all being out-of-phase with each other by 1/12 cycle (which is what we have with the fan), you would *not* hear the original sound. You would hear the 12th harmonic of the volin, and all multiples thereof. In DSP books, it's called a comb filter.
Yeah, but . . . (Score:4, Funny)
That, and now the "Turbo" switch on the front ofthe old machines will be literally accurate--instead of slowing down the machine for old games, it will kick in the generator and boost cpu voltage . . .
hawk
Multiply by the number of blades (Score:5, Insightful)
Re:Multiply by the number of blades (Score:3, Interesting)
They're akin to dipping easter eggs.
Actually, they're akin to dipping easter eggs in hexafluoric acid and making an educated guess as to when the shell has ablated by 2 microns.
Micromachined parts won't be perfect to the last atom until they're milled using a scanning tunnelling microscope.
--Blair
Re:Multiply by the number of blades (Score:2)
Gotme!
they're akin to dipping easter eggs in hexafluoric acid and making an educated guess as to when the shell has ablated by 2 microns.
But they are ablated more or less symmetrically along the whole thing. Perhaps the largest irregularity is temperature gradient. It's different from a piece that's machined in a lathe, in that the machined piece is deformed by vibrations in an additive way, that is, rotation induced vibrations are always in the same direction.
Re: (Score:2)
Re:2.4 million RPM (Score:2, Funny)
You think the dogs are going to go nuts?
That's nothing compared to how the ladies will be acting when they start making 2.4 million RPM vibrators...
Re:Does that work with cats too? (Score:3, Interesting)
No. My parents always had cats at home, and, as a teenager, I did a lot of experimenting with electronics. Cats do not mind sounds above 20 kHz (maybe they can't hear them?). They hate mostly the sounds between 8 and 12 kHz. Not coincidentally, that's the frequency range of the "hissing" sound cats make when annoyed or angry.
What's the fuel? (Score:2, Insightful)
greg
Re:What's the fuel? (Score:2)
Re:What's the fuel? (Score:2)
Gasoline won't work (Score:2, Insightful)
Hydrogen should be what fuels this nation and we should make that move as soon as possible. We have everything to gain and absolutely nothing to lose.
Re:think again (Score:2)
So yes, you have to expend energy to get hydrogen. It is in effect simply an energy storage vehicle. But the energy we need to do it is being beamed to us free of charge from good old Mr. Sun. In other words, it's a good way to take advantage of (and solve the problems of) direct solar energy.
Heat kills (Score:3, Funny)
~wally
Re:Mini-Turbans (Score:2, Funny)
Actually, I've found the single biggest obstacle to be working with those tiny pieces of linen.. I'm hoping nanotech will provide me with a solution in the near future.
Re:Heat kills (Score:2)
It's spelled "turbine".
heat (Score:5, Funny)
"Reach out and torch someone."
-tim
Re:heat (Score:2)
Torch Yourself (Score:2)
Here's a clickable link (Score:2, Informative)
http://www.sciam.com/news/101101/3.html [sciam.com]
As penance, I'll plagiarize some text for my honorable master, the slashdot audience:
Novel Semiconductor Device Heats and Cools on a Dime
[...] Rama Venkatasubramanian and co-workers, publishing in today's Nature, built a faster and more powerful than ordinary thermoelectric device, which converts heat and electricity back and forth, by alternating very thin layers of two semiconducing materials. This film-made of bismuth, antimony and tellurium-is 2.4 times more efficient than conventional bulk devices, 23,000 times faster, and can be applied in tiny dots for pinpoint refrigeration. "This marks a major advance in a field that has stagnated for 30 years," says John Pazik of the Office of Naval Research, which provided funding for the research.
Thermoelectric devices are longer lasting and tougher than mechanical refrigerators. Their high cost and low efficiency, though, have generally confined them to niche markets: powering deep-space probes, cooling infrared detectors, and, lately, heating and cooling luxury car seats. Cheaper, more convenient thermoelectrics could speed up microprocessors and fiber-optic lines, make possible miniature biotech tools capable of stopping and starting small biochemical reactions, or running a car's air conditioner with waste heat from the engine.
-Pimproot, betting his transplantable head on the Promised Land of scientific salvation
Radio controlled electronic bee? (Score:3, Interesting)
There was a movie at some time or other where they had an electronic bee, run by remote control. A tiny power generator could make such things possible in the not-so-distant future. Imagine how far we've come.
There was a discussion several days ago about batteries that are refilled with gas, rather than recharged. It sounds rather messy to me, while a system that uses a hydrogen generator certainly sounds cleaner and more efficient.
I wonder what kind of noise this system makes. If it is very quiet, we may very soon find that batteries in some of the higher end consumer devices are replaced by some mechanical generator such as this.
It may even be suitable for use in larger power generation scheme. Think of clustering a whole bunch of these tiny generators. Although they are currently quite expensive to manufacture, I believe that micromachines and nanotech will soon advance to such a level that it will be very possible to mass produce tiny machines.
Which brings me to the idea of tiny machines that have their own built-in hydrogen power generator. Now that's technology!
Oh well.
Re:Radio controlled electronic bee? (Score:2)
Maybe with this technology, they won't need the roach.
Why? (Score:4, Offtopic)
I'll agree that it's cool to take things that we are used to at macroscopic scales and make them tiny, but it usually isn't going to be an efficient way of doing anything.
Re:Why? (Score:3, Insightful)
The problem with fuel cells is that they're BIG for the power that they produce. A turbine is small for the power that it produces. So this dime-sized turbine supposedly generates 20W of power. How big of a fuel cell do you need in order to get 20W out of hydrogen?
I don't know the numbers myself. It could very well be that a fuel cell's power-to-volume ratio is good enough that you could still manage to power a laptop off of one. But since it's not as good as a turbine, that means that the turbine-powered "battery" pack would have more space available for fuel.
Even better, a turbine's efficiency (potentially) increases as you get it smaller. The major stumbling block for turbines is making the fan strong enough to handle the huge stresses that are put on it by the awesome speeds at which it rotates. But as a turbine gets smaller, its strength increases: mass decreases as the cube, but the various strength measurements (torsional, tensile, etc.) decrease by the square of the size. Silicon is far too weak for full-sized turbines, but (apparently) it works just fine for these submini turbines.
Re:Why? (Score:2, Informative)
Re:Why? (Score:3, Insightful)
Fuel cells will win in efficiency. Probably by a large margin.
Perhaps turbines have other advantages...
I don't know... (Score:2)
You may as well question, I dunno, the flavor of Applejacks or something!
For exosceleton (Score:2, Insightful)
Anyway, it is not fruitful to shootdown good research just because nobody can't come up with application in a second. The question why anyone wants tiny hydrogen-powered turbine generator will be definetly ansered in future.
-- Nyri
Re:Why? - Dirty Fuel (Score:2)
Any contaminants can reduce the efficiency of a fuel cell significantly, whereas only a significant build up of 'sticky' contamination will effect a turbine significantly.
Re:Why? - Dirty Fuel (Score:2)
Big generators (Score:2)
You get the added bonus of your turbines not eating fish, too. All you need to do is cheapen these tiny generators down below the price of a big turbine per unit volume.
pretty obvious why, if you read the story (Score:2)
The author doesn't specify whether "regular power station" means hydroelectric or not, but if this is three orders of magnitude less efficient by volume than a regular large power station, it's exceedingly unlikely that putting a lot of them side by side would be a smart solution.
Of course, who knows how it would behave if the turbine were powered by flowing water rather than hydrogen combustion.
Re: Big generators are better (Score:2)
Re:Big generators (Score:2)
Bin Laden might be interested... (Score:3, Funny)
Don't cry over spilled hydrogen? (Score:2, Insightful)
I'm no expert, but I think the fuel itself could pose some problems. Anyone have more info?
Re:Don't cry over spilled hydrogen? (Score:2)
So what happens when you spill some liquid hydrogen into your expensive laptop?
It will run better :-) We've had umpteen Slashdot articles about the most effective way of cooling your PC, this tops the lot.
I think the fuel itself could pose some problems
Only if you manage to flood your laptop with liquid hydrogen, get your finger wedged in the case for a few seconds, then upon dislodging accidentally knock it against a wall.
Phillip.
Re:Don't cry over spilled hydrogen? (Score:2)
It would be compressed gaseous hydrogen. I'm not sure about what pressure would be best -- the higher the pressure, the smaller the tank, but also the thicker the walls have to be and the more hazardous it is if it ruptures.
More likely, by the time this gets to real world applications it will run on butane. (Butane is a gas at room temperature and pressure, but it turns liquid at room temperature and moderate pressures that even unreinforced plastic can hold.)
For you engineering types (Score:4, Informative)
Luc Frechette just published ASSESSMENT OF VISCOUS FLOWS IN HIGH-SPEED MICRO ROTATING MACHINERY FOR ENERGY CONVERSION APPLICATIONS [columbia.edu] in which he lays out the constraints of micro-motors and how he hopes to overcome them.
cheaper material (Score:2)
Side-Note: Unavailable spokespersons (Score:3, Funny)
Louise, baby, try to finish your stories prior to Thanksgiving weekend next time...sheesh...
Just hype? Again? (Score:3, Insightful)
I'm sure a couple years will pass and we'll all wonder what happened to that "micro turbine thing". We won't be discussing it much, though, because
Something interesting I saw at work one morning.. (Score:2)
An interesting story..
A few years ago when I used to be a SysAdmin for U of A's Chemistry Department, I remember one morning coming into the lab and seeing a group of grad students huddled around an SGI terminal, where the teacher was giving a demonstration. The demonstration was of a "hydrogen ion engine"..One of the faculty researchers within the department had managed to successfully model the tail section of a spermatazoa using a 3D molecular modeller we had. After giving a short (somewhat technical) explanation of the atomic structure of the tail, he demonstrated how the "motor" of a spermatazoa tail works. The sperm absorbs hydrogen ions with its head, and passes them through its body to the tail section. The interaction of a single hydrogen atom with a portion of the tail section causes the entire base of the tail to whip around 360 degrees, like the crank shaft on a car engine. The simulation was played, so that the students could see how hydrogen ions were absorbed, and essentially turned into fuel for the motor housed within the tail of the sperm.
Keep in mind, this wasn't a "simulation". The software being used is an atomic modeller and conformation engine designed to run on supercomputers that costs a hefty $15,000 per license. It was quite a feat to completely reconstruct the tail of a spermatazoa out of individual atoms and have it function exactly as it does in nature.
Cheers,
Let's get real (Score:2)
(similar issue with fuel cells, too, for that matter.)
-dB
Rovers! (Score:2)
Does that mean we'll see an upgrade with this for Mindrover?!? Woohoo!
Re: (Score:2)
Re:First Power! (Score:2)
Re:First Power! (Score:3, Informative)
This is why hydrogen is being looked at so heavily as an "alternative" fuel source -- it's abundant, clean, and very inexpensive.
one small detail (Score:2, Interesting)
so where do you plan to get your H2 from? (Score:3, Insightful)
To burn the stuff, you first have to split it from whatever it is bound to, and that takes some deltaE.
In fact, it takes as much deltaE to split the hudrogen off as you get back by burning it and puttign the bonds back together (first order calcs).
Hydrogen is a *storage* fuel. It is simply a new way to take energy from one place and move it to elsewhere, where it might be more convenient to use it.
If you plan on using hydrogen to create a lot of usable energy storage, as in to replace some of our curent fossil fuel dependency, you have to get the energy from somewhere. Like say, fossil fuel.
Or nukes, or some such thing.
The point is, it can't reduce our curent dependency on our current fuel sources (well, it might add some efficiency at sa few points, like al.owing us to use excess generating capacity at off-peak hours. The laws of thermo-goddamnics still apply.
Hydrogen technology doesn't create any new energy reserves, it simply allows us to store some of our energy reserves in a different (H2) and potentially differently-useful form.
Re:so where do you plan to get your H2 from? (Score:2)
add to this that, yes the by product of H-O combustion is water, but to get hydrogen out of any hydrocarbon, you always get CO2 or NO2. Combustion reactions always follow the form
Fuel+O2 -- CO2/NO2+H2O+energy
So while you produce water in the end, you still produce CO2.
~z
Re:so where do you plan to get your H2 from? (Score:2)
Re:so where do you plan to get your H2 from? (Score:3, Informative)
Re:so where do you plan to get your H2 from? (Score:2)
So basically what we need then, are large solar powered water-to-hydrogen converter platforms located out off of the coasts. It's "real estate" that practically has no value at the moment, it has plenty of water, and plenty of skyline, and no other current use.
Not really (Score:2)
I don't know about you, but covering thousands of square miles of ocean surface seems... unwise.
Go with nuclear, cause everything else just sucks more.
Re:First Power! (Score:2)
Re:First Power! (Score:2)
The small amount of hydrogen (per device) to manufactured would have less environmental impact than the alloy and chemical production for lithium battiers. Would be lighter too, no more 10lb. dual battery dell laptops to lug around, hopefully.
Re:First Power! (Score:2)
Last time I looked water was not a pollutant. But you better check with Greenpeace/Sierra Club/NRDC..... Anything beyond a horse and buggy can't be good for you.
oh, no! (Score:2)
> withGreenpeace/Sierra Club/NRDC..... Anything beyond a horse and
> buggy can't be good for you.
Ack! the dreaded dihydrous oxide! quick, ban it! for the children! It causes drownings, crop failures, and electrical fires . . .
hawk
Re:oh, no! (Score:2)
nonetheless, even if they use a funny (albeit chemically more descriptive) name, their helpis welcome.
Re:First Power! (Score:3, Informative)
You wish. Actually, burning hydrogen in air generates some NOx emissions. Hydrogen in air is a complicated combustion system. NASA has been working on scramjet designs that burn hydrogen in air, so this problem is gettimg some attention. It's the subject of some big number-crunching simulations.
If you want a totally clean burn, you have to burn hydrogen in pure oxygen.
Re:First Power! (Score:2)
Hats off to ya.
Re:Heat is a pollutant (Score:2)
Heat pollusion is definately a concern for areas with sensitive ecosystems. Good point.
Re:No such thing as a free lunch (Score:2)
Re:No such thing as a free lunch (Score:2)
As opposed to fossil fuels, which send their pollution into everyone's air? At least nuclear waste can be carted away from MBY, to somewhere like Nevada, where they seem to have a pretty expansive view of what consists of their BY's.
Re:No such thing as a free lunch (Score:3, Insightful)
That's incredible really.
Imagine, all the electricity needs of a family of four for 40 years generate about 3 pounds of fuel waste.
Re:No such thing as a free lunch (Score:2)
Surprisingly, industrial hydrogen production does not make use of hydrolysis. It is actually not cost effective, when compared with other chemical reactions.
Re:No such thing as a free lunch (Score:2)
... or solar or wind power, or tidal power, or fusion, or any other power source that mankind figures out how to harness in the next million years. The cool thing about hydrogen is that it allows us to disassociate the method of power generation from the machines that use the fuel. Electricity has already done this for stationary appliances--your television doesn't care whether it's running on electricity made from coal or fusion. Hydrogen promises to give us the same flexibility for vehicles and fuel storage; that way, every time a newer, cleaner method of power generation comes on line, we don't have to replace every car and generator in the world.
Think of hydrogen as the XML of fuels.
Re:First Power! (Score:2)
Ecologists are scientists studying the way life interrelates. Systems analysts, really.
Environmentalists are people that try to limit damage to the ecosphere by indifference, greed, or maliciousness.
Conservationists, like the Sierra Club, are not necessarily either of the two above. They are usually more conservative, politically, and don't have the fire of the environmentalists. They compromise; they support hunting; they can be both a backpacker and a driver of an SUV.
Notice I ddin't mention the Greens. They are environmentalists that are really pissed. And I can't blame them, really.
Re:First Power! (Score:3, Insightful)
"And isn't this kind of a step back in our attempt to stop using fossil fuels..." - I am an American. My goverment has no such policy. All your oil are belong to us. For those of you in conservation minded countries, hyrdrogen is not a fossil fuel. It is a theoretically handy way to store electrical energy. There are technical hurdles. Not insurmountable, just insurmounted. Once there is a demand, there will be a way of distributing and storing the hydrogen.
More like 200-400 watts of heat. (Score:3, Insightful)
The 20-40 watts is the power delivered by the device to the laptop and eventually (except for a miniscule amount leaving as light, radio waves, telephone modem signals, etc.) disipated as heat by the laptop's circuitry.
But the generator is a HEAT ENGINE and this one runs at 10% efficiency. So to generate 40 watts it burns fuel at a 400 watt rate. 40 watts to the laptop, 400-40 = 360 watts of heat in the exhaust.
And you CAN'T improve it very much. It's a heat engine. Perfect efficiency for a heat engine is the carnot cycle limit: 100% * (Th - Tc)/Th.
Call that about 30% for a fuel-burning engine at room temperature, and you're still talking 133 watts of heat sitting on your lap for a 40 watt load. But you can't get anywhere near carnot cycle in a practical device, and the smaller and faster the device the more you'll fall short - you need something like a power-plant to approach it. So back to 10% and 400 watts.
What gets me about the Scientific American article is the apparent claim that the efficiency of batteries is ten times worse. Batteries and fuel cells can approach 100% efficiency.
I think what happened is they confused efficiency with energy density. A battery contains both its fuel and its oxidizer - and oxidizers tend to be heavy, due to heavy atoms and extra atoms to hold them down. Heat engines and fuel cells, on the other hand, can get their oxidizer from the ambient air, and expell the combustion products. So they only need the engine/cell proper plus the fuel tankage. Yes a heat engine would probably beat a battery by a factor of ten on energy density. But a fuel cell, if it can be adequately miniaturized, might do still better.
Nevertheless this engine looks like a good solution (if you're willing to put up with the waste heat), at least until fuel cell technology approaches it in power density.
The use of hydrogen is curious. Handling it is a real bitch. It crawls right through steel and burns with an invisible, super-hot, ultraviolet flame. Very dangerous.
They are probably using it, rather than a liquid hydrocarbon like butane, to simplify the design and to get the maximum energy-density numbers for the engine/tank system. With butane/air you need to do emission control for NOx, CO, and unburned hydrocarbon. With hydrogen/air you only need to sweat NOx. Hydrogen's energy/ounce of fuel is higher and it's easier to light. Liquid hydrocarbons - especially impure and "odorized" formulations - produce a number of combustion products that can potentially foul the engine or its exhaust as well. You don't need fancy controls for a hydrogen engine, while a butane engine might need a catalytic converter and some serious compute power.
What I'd like to know is whatever happened to the ceramic oxygen-concentration fuel cell - the one that uses the same basic cycle as the exhaust-gas oxygen sensor in a car?
Oops - wrong magazine. (Score:2)
Oops. I meant "the Popular Science article".
Re:More like 200-400 watts of heat. (Score:2)
Re:First Power! (Score:2)
HOT water! (Score:2)
Water?
Try superheated steam.
I don't want a jet of THAT coming out of something sitting on my lap. B-)
Re: (Score:2)
Re:Cool Uses - not big enough (Score:2)
And about flashlight life... cockeyed [cockeyed.com] has a series on "how much is inside". Checkout the battery [cockeyed.com] one for a shocker about how much is really in a pair of D cell batteries. Then try to figure out why your flashlight is always almost dead. Who comes in and uses up your flashlight?
Re:Cool Uses (Score:2)
Separate the motor from the mobo, and you have a conventional device, with a gas tank instead of a power cord.
turbine size (Score:2)
Re:Small power station? (Score:2)
The plant where I work has two 1180MW steam tubine generator sets. Each one has moving parts that weigh in at about 800tons, thats 1.6E+06 pounds. Thats a lot of pounds. Compare that to this little (admmitedly very cool) device.
Re:Compressed hydrogen... (Score:5, Informative)
And since this tank is gonna be small, it can be made really freakin tough. Think about how tough a good quality propane cigarette lighter tank is.
Sorry, it's very dangerous. (Score:2)
Sorry, wrong answer. You're underestimating the size of the tank.
Existing lithium cells have "the energy density of a hand grenade" - and weigh about as much as one, so they also have about the energy of one. This has ten times that energy - look at the run time numbers. That's because it's using an external oxidizer in combination with tanked hydrogen. That means it's got a LOT of hydrogen - essentially a small tank of liquid H2.
If you mix the H2 with the appropriate amount of air to burn it efficiently you get the energy of ten hand grenades - call it a couple sticks of dynamite. If it leaks (without initially igniting) inside a building, it will light when it reaches lower explosive limit at a nearby source of ignition - a close approximation to the ideal mixture. The pressure will couple efficiently to the walls and roof, blowing the building apart. The superheated steam left behind will ignite the fragments.
If, on the other hand, it leaks and ignites, you'll have a welding-hot needle flame which is ultraviolet, and thus invisible, poking out some hole in your laptop or playing against something inside it. And it will burn much longer than a butane torch with the same weight of fuel and same flame power.
Meanwhile, hydrogen is a very small molecule and can thus flow rapidly through very small holes - like between the atoms of a steel tank. This means it's much less forgiving about the quality of your tankage, gas plumbing, and valves. Leaks are MUCH more likely to occur.
Re:Sorry, it's very dangerous. (Score:2)
A lot of the destuctive force of explosives has less to do with the energy released than it does with how quickly it is released. Compare the speed of propogation of a shock wave traveling through a hand grenade (6-10,000 Meters per second)to the speed of flame propagation through an ideal hydrogen/oxygen mixture at 1 atmosphere of pressure (~300 Meters per second). A room filled with hydrogen would probably blow out the windows and singe the furniture when it exploded.
Also, in my experience, hydrogen doesn't burn so hot that the resulting steam would even light a match.
As far as I can tell, people are at a greater risk from the explosion from the pilot light on their stove going out.
Re:Sorry, it's very dangerous. (Score:2)
Let's see...
300 meters/sec = 1,080 kilometers/hour. About the speed of sound in air. So it's a shock wave, and all the energy of the mixture's burn (a LOT) is concentrated in the wave front. That should be adequate to blow the building apart. (Of course that's the number for a free-air reaction speed, and a mix inside a building is confined by the building.)
Of course turning the gas mixture into superheated steam behind the shock front is hardly a trivial matter, either. Superheated steam is just dandy for setting anything on fire - and it doesn't get much more superheated than the temperature of steam that has just been formed by an oxidation-reduction reaction. It's only short of the disassociation temperature by the bonding energy of H2 and O2. It transfers the heat nicely to whatever it touches, too, and also releases the heat of vaporization as it condenses on anything that's still below 212 F.
Try putting your hand in a jet of ordinary (not superheated) steam and then tell me how cool it is.
The burning of the hydrogen in hydrocarbon fuels provides the bulk of the heat, you know. The carbon is mostly there to hold the hydrogen together in a convenient package, and slow the reaction speed down to something convenient to handle. Hydrogen burns quite quickly.
Also, in my experience, hydrogen doesn't burn so hot that the resulting steam would even light a match.
That doesn't square with NASA's experience. B-) They find hydrogen leaks by walking slowly and holding out a piece of corrigated cardboard in front. When the cardboard suddenly catches fire they've found the leak. ("There's no such thing as a hydrogen leak that ISN'T on fire.")
Re:Compressed hydrogen... (Score:3, Informative)
Liquid hydrogen is cold at 1 atmosphere of pressure. You can make it as hot as you want, if your container can handle the increased pressure.
Gaseous hydrogen isn't really any more explosive than the butane in your lighter or the natural gas piped all over your house.
You prefer children playing with toys powered by batteries that are packed with lithium, mercury, etc?
Re:Red Bull.... Cold (Score:3, Funny)
If this microturbine can be mass produced for pennies, like many other semiconductors, and eventually we can make a cheap aluminum tubule sandwich sheet that is thin enough to make cans...
We could make disposable self-cooled cans of Budweiser! Who wouldn't marvel at the combination of technology and wastefulness!
Re:2.4 million RPM?! (Score:3, Interesting)
2400000 R/M = 40000 R/S
1 R = 4mm*pi = 12.56mm
40000 R/S = 502656 mm/s linear velocity
503 m/s is pretty fast. Thats about
I havent done basic physics in a long time so i am rusty on the formulas; could someone do the energy/force calculations for me? Just off the top of my head i think 1 milligram (thats the equivalent weight of one cubic millimeter of water, which i think would be about the right order of magnitude for the blades on this turbine) moving at 503 m/s could do some daage to organic tissue, more so than a splinter at least.
Re:2.4 million RPM?! (Score:2)
Re:2.4 million RPM?! (Score:2)
Nah, don't count on that! Let's just hope the mod who got you down will be the one to get the first splinter! He will be looking (very closely) at the turbine, thinking "Hey, there's something burning in there, that's (-1, Flamebait)!" when the thing will blow up and the splint will hit his eye...
Re:What about the noise. (Score:2)
Nonetheless, the turbine tip speeds *are* "high subsonic or low supersonic" according to Frechette's papers. The turbine housing can reasonably be expected to damp external noise quite a bit.
Re:Tesla Turbine (Score:2)
Yes he did. But it rotates at a VERY high speed - high enough that the centripital force on the working fluid matches the pressure difference between the input and output ports. Tough to balance. Lots of friction between the gas and the outer housing to create inefficiencies. Enormous forces in the turbine material itself.
Bladed designs have proven more practical for general use.
Even there there's an interesting instability problem: The shaft has a resonance - the frequency it would "ring" in the oscilatory mode where the bar is beneding up at the ends and down in the middle. When the turbine's rotational speed approaches this resonance it pumps energy into it and tends to tear the turbine apart. The trick is to provide support that can damp this vibration for long enough to get the rotational speed up beyond the magic rate.
This design seems to sidestep the problem by flattening the turbine into a pancake.
Waste gas = steam (Score:2)
Generally one pumps it through cooling baffles into the atmosphere. Then, of course, you have to manage the condensate drip.
It's an excellent question, and one that will have to be answered before this thing can see practical use.
I'd like to see what the actual generator design will be - all I see in the articles is a motor, not any sort of electrical generator.
This motor is interesting as pure research. I'd have done a bladeless turbine (if I could manage to get paid for doing stuff like this) but that might not be as much of a challenge to build and thus less interesting on grant applications.
I haven't seen anyone proposing any commercially viable use as yet - without a generator, ignition system and waste gas management scheme it's just a cool toy.
--Charlie