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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."
It's not like a heat pump turns heat into nothing. One side of a heat pump gets cold, the other side gets hot. At half a micron across, it's hard to see how such a device could help evacuate heat from a CPU.
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?
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.
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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It always amuses me when people try to raise performance as a point against a first generation lab prototype vs. a tenth generation refined technology in production. The question is not whether these piezoelectric heat engines/pumps are more efficient than peltiers now, but rather can they be more efficient than peltiers in the future after further development, or is there a foreseeable upper limit to the technology that makes such an application unlikely even with development?
There *is* a need for heat reduction at very small scales, especially in mobile devices or even the implant devices of the future. Of course heat has to go somewhere, the only issue is that the destination of the heat be better able to deal with it than the source.
I support the Slashcott and will not be reading or commenting from 2/10/14 to 2/17/14. Beta is steaming pile of dog shit
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?
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.