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Heat Engines Shrunk By Seven Orders of Magnitude
KentuckyFC writes "The vast majority of motors that power our planes, trains, and automobiles are heat engines. They rely on the rapid expansion of gas as it heats up to generate movement. But attempts to shrink them by any significant amount have mostly ended in failure. Today, the smallest heat engines have a volume of some 10^7 cubic micrometers. Now group of Dutch engineers has built a heat engine that is seven orders of magnitude smaller than this. The engine consists of a piezoelectric bar that expands and contracts in the normal piezoelectric way. However it also heats up and cools at the same time causing a thermal expansion and contraction, which lags the piezoelectric displacement. By carefully choosing the frequency of the driving AC current, the Dutch team found a resonant effect in which the thermal expansion and contraction amplifies the mechanical motion, making it a true heat engine. Operating the thermodynamic cycle in reverse turns the device into a heat pump or refrigerator. The total volume of the device is just 0.5 cubic micrometres."
Great, let's make this 500 times bigger and power my car!
Great! When can I get these built into my CPUs?
When our name is on the back of your car, we're behind you all the way!
Its a heat engine but it does not use gas, so maybe this could be the engine for a train of nano bots! Or we can use them to cool our CPUs. Interesting indeed, now we need to find an use for it
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Can the physics gurus please put cubic micrometers in perspective for us common mortals? Is that as big as a grain of rice or a head of a pin?
10^7 micrometers is.... a spehrical cow? a toaster?
Can it be used for other things?
How many beer cans fit in a 0.5 micrometers refrigerator?
Somehow "heat engine" directly translates into "internal combustion engine" for me. But this piece uses electricity, exactly how useful is that? This is bound to be less efficient than to use the electricity to just power an ordinary electric motor. I suppose scaling a motor down to that size might be kinda difficult, though, if that was the point, why emphasize that it is a heat engine?
Peltier diode?
It is so small that it produces a very minimal amount of horsepower, which is not useful for any actual way.
Unless of course you have several billion of them on a gram sized object. If you can't see the value in jet powered ants you should turn in your nerd card.
Seven puppies were harmed during the making of this post.
Finally my plan for steampunk (almost)nanobots can come to fruition! Those millions in grant money to the blacksmith have finally paid off.
Assuming we had micro engines, we can take full advantege of many things that are better smaller than bigger.
For example, a small device that turns heat into power could power an IMPLANTABLE MEDICAL DEVICE using the bodies own heating/cooling systems? No more changing the battery for the pacemaker every
Then there are small flying devices. I am sure the military would love a flying camera the size of a real fly that uses the solar heat of the sun to power it.
Then there are phones and musical devices. Want one that uses half of its' own waste heat to recharge itself, perhaps doubling battery life?
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I guess the Logopolians will have to spend even more time doing base block calculations to prevent the heat death of the universe.....
Tsukasa: All I really want, is to be left alone...
Apparently there are 0.001mm^2 engines already!
There's a reason we don't already use the waste heat for recharging electronics... because it's damn expensive. There are far better components for turning a heat gradient into electricity than this type of motor.
Looking at your other examples... the promise of this device is not in turning heat into electrical power. It's about turning heat into physical power. Think transport of tiny, tiny objects (microsurgery for vascular repair, for example).
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You mean a hatchback?
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So as you shrink things, pretty soon, you can't start a fire. The fire loses heat over its surface area faster than itrs volume can generate it.
Which is why you don't see flames smaller than a certain, much larger than micrometer, size.
So if I'm understanding this argument correctly, the limitation can also be understood in terms of the time window available in which to extract the energy decreases, as the engine scales down. At a material level, the heat dissipation has a limit as well -- for conduction, it can't be any faster than the speed of sound (within the material comprising the engine).
While we don't have any information on the frequency at which the piezo engine operates, it could be very high, allowing for nearly instant energy extraction. We could possibly be approaching the limit at which the two limitations compete.
And I despair of the lack of English education, specifically reading comprehension.
This isn't internal combustion, which is what your argument is based on. It uses the fact that solids expand and contract when heated and cooled, including some piezo materials.
Please read the summary *again*.
It's almost as pathetic as the idiots who assume heat engine == combustion engine.
This reference may be relevant: http://www.ingentaconnect.com/content/tandf/umte/1998/00000002/00000002/art00006?crawler=true "...Results from this study show that a small-scale heat engine fabricated from a low-thermal-conductivity material can be made with a length scale approaching 1 mm. Such a device would undoubtedly be composed of numerous microscale components. Below the 1-mm limit, efficiency suffers to such a degree that solid-state thermoelectric devices would become a better choice for a particular application. "
The total volume of the device is just 0.5 cubic micrometres.
I know I parked my car around here somewhere. Anyone see it?
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
So thats like much smaller than a womp rat!
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It's the basic SCALING LAW that Galilleo figured out like 600 years ago.
As you make things smaller, their volume, which is their abilitry to burn fuel, goes down as the CUBE of its linear dimension.
But its surface area, which is how it loses heat, only goes down as the square.
That'd be Newton's law of cooling, no more than 300 years old.
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I doubt they're trying to oxidize fuel in that volume - more likely they are transferring heat from one volume of gas to another.
How did this get +3 informative?
How about -1 "did not read the summary and assumed it was an IC engine".
Or rather a SUV is just a bigger Hatchback.
As an engineer that works with heat engines. I don't see what is so difficult about making a small heat engine. However, if one were to make a heat engine seven orders of magnitude smaller, with the same efficiency of a full sized heat engine... THAT would be an accomplishment!
Unfortunately, both the article and the summary have left out that detail...
One of our competitors trademarked the term "hypothesis". From now on, we will call them "boneheaded ideas".
Finally, a refrigeration unit compact enough to let me get some sharks with frikkin' lasers on their heads!
when i saw the title i said "wow". then i read the summary, and i said "wow" again. that makes it a double-wow.
What has happened to Slashdot? Who do you have to be a Guru in every subject to read Slashdot?
Looks like gone are the days when all you needed to good discussions on Slashdot was genuine curiosity and decent , not necessarily perfect, grasp of English language. And no, being a know-all, done-all master of the universe was not required either.
While I can perfectly understand saying "You are making a mistake" or "That's not what the article says", I have never really understood calling someone pathetic for not knowing something.
The range of topics covered here is very wide and I don't know abc of several things discussed here. Does that make me stupid and pathetic?
In Soviet Russia, engine...does not heat you. :(
heat engine != ICE... no fire needed.
All of the above was encrypted with a Quad ROT-13 method. Unauthorized decryption is in violation of the DMCA.
To be fair, its a poorly written summary that can easily cause anyone who doesn't have a background in this area of engineering to assume it's only talking about internal combustion engines because of the first two to three sentence:
"The vast majority of motors that power our planes, trains, and automobiles are heat engines. They rely on the rapid expansion of gas as it heats up to generate movement. But attempts to shrink them by any significant amount have mostly ended in failure."
This could be interpreted by many as "Heat engines, like those we use to power vehicles, rely on the rapid expansion of gas as it heats to generate movement, and engineers have been unable to shrink them by any significant amount". The summary could have been much clearer by defining a heat engine has any device that converts heat to mechanical work, and stated that internal combustion engines are one type of heat engine, but there are other types as well.
Even when I first read it, I was thinking "How'd they even get an internal combustion engine down to 10^7 cubic micrometers?". It would have been helpful if it described that heat engine as well, since it's obviously not internal combustion.
What does Immigration and Customs Enforcement have to do with piezoelectric heat engines?
Not only is 10 million much easier to understand than 10^7, but 0.01 cubic millimeters is a MUCH more common number, and measurement.
Not exactly hidden information either.
The range of topics covered here is very wide and I don't know abc of several things discussed here. Does that make me stupid and pathetic?
The key point is that you recognize that you don't know everything about the topic at hand. The post that sunking2 was responding to was essentially a spew of vitriol against the researchers, claiming that it's impossible to make such a small engine with any sort of efficiency, and that they're stupid and ignorant for even trying. According to that post's replies, the writer is completely wrong and doesn't know some basic facts about the subject they're yelling about.
So, no, you're not at all stupid and pathetic for not knowing everything about everything, and I'm in the same boat with you (I've learned a fair amount from this story's discussion), but neither of us is telling everyone (including the Dutch engineers in question) that they're stupid and don't know what they're talking about.
Now they don't have to peddle to work each day. The nanites can make a cool ride with one of these motors.
jsut athnoer menagiensls ltitle psrhae for you to dcoede. Why do we wtsae our tmie dnoig tihs?
Have you played Metroid Prime on the Gamecube? The first game, in Norfair, there's a geothermal power station with giant cylinders embedded in volcanic walls suspended just above the lava flow. They constantly pump. They're... HUGE.... I thought it was pretty epic, considering the larger engine would have a higher total efficiency; but I never figured out how the rock face would be cool enough to support high efficiencies (it's not molten, but it's still fucking hot). Just an interesting thought for you, since it seems to be in your field and I figure you might find the cultural reference (and the associated mind games trying to work out if/how this would work in real life) pleasant.
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I agree that using cubic micrometers is nowhere near intuitive.
1 um (replace "u" with the Greek letter "mu" please) is 1e-6 metres.
So, 1 cubic um is 1e-18 cubic metres. So, the smallest conventional heat engines are 1e7 of these 1e-18 cubic metres, or 1e-11 cubic metres.
Not that intuitive either. So we'll use cubic mm.
1mm is 1e-3 metres, so 1 cubic mm is 1e-9 cubic metres.
Something that's 1e-11 cubic m (1e7 cubic um) is 1e-2 cubic mm. So, it's 1% of 1 cubic millimetre.
That's pretty small.
404555974007725459910684486621289147856453481154 in hex is "You sank my Battleship?"
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No, your post was polite and respectful, so you're not stupid and pathetic (even though I don't agree with you). The original ("Reedeeculous") post was both incorrect and rude, and the response was appropriate (correct and rude). If the original post had been incorrect and polite, I'm sure the tone of the responses would be very different. If you act like a know-it-all, don't be surprised if someone who knows more than you decides to teach you some humility.
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Looks like gone are the days when all you needed to good discussions on Slashdot was genuine curiosity and decent , not necessarily perfect, grasp of English language. And no, being a know-all, done-all master of the universe was not required either.
True but you were also expected to recognize that you were not a know-all done-all master... There was never a time on /. where someone who said "I'm right and all these fools have no idea what they're doing" wouldn't result in the poster being smacked down if they were wrong.
While I can perfectly understand saying "You are making a mistake" or "That's not what the article says", I have never really understood calling someone pathetic for not knowing something.
Not knowing something is not pathetic. Acting like you know when you don't, and calling the people who do know idiots, is pathetic and I have no issue with someone being called out on that.
See, you're forgetting the other half of slashdot posting that has changed the OP. It used to be much more common to see a post that would say something like "I thought cube/square scaling laws implied that you can't have an efficient heat engine below a certain size because the heat would dissipate faster than you could generate it. How does this invention get around that?" or "I don't really get QM, so can some explain how it's possible something to be in two states at once, and why electrons are shown as 'clouds'? Doesn't the electron have to actually be somewhere?"
Nowadays there's a lot more like the OP. "Oh my god, even Gallileo could have figured that these idiots invention couldn't possibly work!" or "Something can't be in two states simultaneously! So obviously QM is wrong and stupid. I can't believe there are so many idiots who blindly believe in that dogmatic bullshit!"
There's still some of the former, and always were the later. But seriously, I don't think it's that Slashdot has changed when a post that starts off "Reeeeeedonculous!" attracts people ready to tear it down.
The enemies of Democracy are
well ... the statement
"The range of topics covered here is very wide and I don't know abc of several things discussed here"
makes you 'wise' in the Socratic sense, negating the description "stupid"
unfortunately, the location of this discussion reinforces the second descriptor
+1 fashionably cynical
if this is useful. I've seen micro rotary and piston engine. They suffer from two problems. One is heat loss due to high surface area to volume ratio (heat leaks away before work can be extracted), and the other is charge (fuel/air) leakage. This appears to solve the leakage problem buy not using combustion. Good job!
For example, a small device that turns heat into power could power an IMPLANTABLE MEDICAL DEVICE using the bodies own heating/cooling systems? No more changing the battery for the pacemaker every
Depends... what are you going to use for the cold sink when the implant is surrounded by flesh that's all at 38 degrees?
If God forks the Universe every time you roll a die, he'd better have a damned good memory.
For example, a small device that turns heat into power could power an IMPLANTABLE MEDICAL DEVICE using the bodies own heating/cooling systems?
How would that work?
To power a heat engine, you need a temperature difference.
To power a heat engine efficiently, you need a temperature difference significant in comparison to the absolute temperatures.
As the temperature difference approaches 0, the efficiency approaches 0.
The maximum theoretical efficiency between body temperature and body temperatue + 3C is about 1%
How much of a temperature difference do you think you can find within the human body across a machine of a few micormeters (or even millimeters) in length?
At what scale do you expect the horsepower to be useful? A micrometer engine won't power your SUV, but if you want to create extremely small ducted fans that can be embedded in a processor, for example, I think it has the horsepower to push air.
Although that raises the immediate question of what happens if the mechanism gets clogged by dust or something. At that scale, there ain't shit you can do to clean it.
I read the attached paper on arxiv, and from what I could tell, they passed a DC current through the thing, which caused the small engine beam to expand, causing it to heat up and move the mass. The piezoelectric effect causes the resistance in the small engine beam to change, which causes the beam to cool down and move the mass back with help from the larger spring beam. Rinse, repeat. Effectively a thermoelectric buzzer. The buzzing of this particular device was measured to be about 1.255 MHz at a DC current of 1.045 mA.
Unlike what the Technology Review article says, the paper shows no application of an AC current to get the thing vibrating. In fact, the measured voltage is alternating because the resistance is alternating. The current remains the same. There is no complicated application of a DC current and an AC current. There's just an applied DC current.
Am I understanding the paper correctly?
Towards the Singularity.
... but neither of us is telling everyone (including the Dutch engineers in question) that they're stupid and don't know what they're talking about.
Don't worry. That's just the usual style of Dutch engineering discourse.
Therefore, by the (faulty) logic you're using, you're just a cow with a keyboard - osu-neko (2604)
If the solenoid is electrically driven, is it really an engine by the definition above (reciprocating)?
I mean sure, the piston reciprocates, but not as part of power generation like in an ICE. I suppose the object being physically acted upon would see the solenoid piston as the source of power.
It seems that viewing a solenoid as an engine means that electricity is the fuel, and my mind is choking on that.
Is electricity as "fuel" to a solenoid as electric engine a valid analogy?
Am I on the right track here, or simply out to lunch?
it makes no difference if it's an IC engine or ZC.
The issue is the same. To have a heat engine you need separate regions, one hot and one cold. As the regions get smaller, you lose the ability to keep the hot away from the cold. By the time you're down to 1 centimeter, a large fraction of the heat is lost thru conduction. And it just gets worse from there on down.
And using differential expansion of a solid is a horribly inefficient scheme-- you may have noticed a certain lack of cars powered by the expansion of their tailpipes.
>Please read the summary *again*.
yes, you read it again too, especially this part:
Below the 1-mm limit, efficiency suffers to such a degree that solid-state thermoelectric devices would become a better choice for a particular application. "
So this device is rated NFG at smaller sizes, by the inventors themselves. .. and I havent even touched on how friction and surface tension also go down as the square, making moving parts below a certain size just plain useless.
How much of a temperature difference do you think you can find within the human body across a machine of a few micormeters (or even millimeters) in length?
That's what the 12" heat sink sticking out of your chest is for. That, and impressing the ladies.
If I have been able to see further than others, it is because I bought a pair of binoculars.
While that's certainly interesting, wouldn't you just use an electric motor anywhere electricity was available?
Oh, wait. It's use as a heat pump at that size is notable, but as a motor:
> It's future as a motor is less clear. It's relatively straightforward to make
> electrostatic motors that work on this scale and we've looked at plans to
> build electric motors on the quantum scale.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
Hey, you and I said the same thing in response to the same post, and we both italicized "recognize" in the first sentence!
:P
Stop copying me!
Stop copying me then traveling back in time to post first! Total waste of a time machine. ;)
The enemies of Democracy are
... they passed a DC current through the thing, which caused the small engine beam to expand, causing it to heat up and move the mass. The piezoelectric effect causes the resistance in the small engine beam to change, which causes the beam to cool down and move the mass back with help from the larger spring beam. Rinse, repeat. Effectively a thermoelectric buzzer. ... Am I understanding the paper correctly?
As far as you went.
But the alternating heating/cooling doesn't have to come from current through the material. It could come from alternating heating/cooling of its environment, for instance. Like by periodically-varying temperature changes in a fluid or high-intensity illumination.
Thermoacoustic machinery operates by using very high intensity sound - high enough that it makes major periodic temperature changes in the working fluid due to compression and rarefaction. This is used to build heat engines and heat pumps, sometimes with no moving parts but a gas. And it can operate at small scales and high frequencies.
It will be interesting to see if arrays of devices using this technology can make a better electrical interface for pulling power out of or putting it into a thermoacoustic device than piezoelectric devices working just on mechanical coupling to the motion of the working fluid.
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It's damn expensive, using CURRENT technology. This is new technology. I.E. you have no idea if this is going to be expensive or not using it. But you are right about my mistaking physical for electrical.
excitingthingstodo.blogspot.com
The body has multiple mechanism of disposing of heat. It is FULL of temperature differences. That is not the problem. Ever go out in the cold? Notice your hands get cold but your chest does not? You can easily get more than 3 degrees celsius. The problem as someone else mentioned is that this converts heat to kinetic, not electrical.
excitingthingstodo.blogspot.com
How much of a temperature difference do you think you can find within the human body across a machine of a few micormeters (or even millimeters) in length?
That's what the 12" heat sink sticking out of your chest is for. That, and impressing the ladies.
I think they'd be more impressed if that 12" "heat sink" was closer to waist height.