Problems with classical thermodynamics

[Duda Jarek]

I was recently interested by some news that it's possible to drain energy from pure heat. I've read about two ways: use sound resonator or absorb infrared thermal radiation:

http://www.physorg.com/news100141616.html

http://www.physorg.com/news137648388.html

Other problem is for example that while spontaneous crystallization entropy goes in 'forbidden' direction:

http://www.garai-research.com/research%20statement/Entropy/Entropy.htm

...

 

It would be nice to localize simplifications of looking to be such general theory like thermodynamics.

One way of their reasons can be simplifying physics for thermodynamical model, like

- it corresponds to molecules, while we can say that their electrons live in completely different world - on a scaffolding made of molecules. Their energies doesn't correspond straightforwardly,

- thermodynamics usually ignores thermal radiation and it's energy.

 

But maybe there are deeper problems - thermodynamics usually ignores internal structure - for example from two states of the same energy one can be easier accesable...

 

What do You think about it?

[CaptainPanic]

Here you have something about acoustics and heat: the acoustic heat engine. It's the same as the first link you posted, but I think it's a better explanation.

http://www.aster-thermoacoustics.com/indexeng.html

 

But in any case, heat alone is useless. You'll need a temperature difference. If you have heat, you also need a cold side, or you will go nowhere.

 

Utilize heat:

An old proven way to utilize heat is the steam engine. It will run on any kind of heat, and you can make a solar steam engine, although that may have some practical drawbacks. Sterling engines work on heat alone as well. Solar boilers heat up water, although these work on solar power (insolation, rather than pure heat). The Seebeck-effect describes how you can turn a temperature difference straight into electricity (though not very efficiently).

[Duda Jarek]

When I've met with a heat to sound article, it was written that it needs pure heat ... but when I've read physorg article I've linked - I've finally seen that it uses gradient of temperature...

 

But what about nanoantennas?

They use heat energy - thermal infrared to enforce movement of electrons.

The problem is if we can change it into their regular movement - we would need diodes which would be something like Maxwell's demon for electron...

I think that it's possible, because temperature describes average temperature of molecules. But their electrons have completely different behavior - are much faster, have different energies, move along scaffolding made of molecules ...

There are two different thermodynamics there! Of course there are correspondences/interactions between them, but there is also some independence we may be able to use... ?

 

Simple counterexample to 2nd law using thermal photons:

 

Imagine empty tube, which internal surface is covered with perfect mirror. Now near it's one end place two separators - reflective on the end of the tube and transparent to its middle.

Place hot gas between the separators. It's isolated thermally, but it produce thermal photons. The only way photon can escape is through the second end of the tube, so it would work as jet engine - because photons have momentum in one side, the tube has to get momentum into the second. And we have stream of photons we can use to create work somewhere else.

 

Above example uses that despite that kinetic energy of molecules behave randomly, each one has specific movement/oscillation, which energy can be changed into ordered one - electromagnetic oscillation of photon.

You will say that the problem is with perfect mirrors, but they are just a perfect isolator for thermodynamics of photons.

Edited August 27, 2008 by Duda Jarek
multiple post merged

[Duda Jarek]

I see how to make the required nanodiodes for nanoantennas for thermal photons - they should use that after absorbing a photon, the electron will be excited and will slowly equalize this additional energy with its environment.

So if we place something which need high energy electron nearer one side of antenna, it's more likely that electron jump through this threshold.

 

So the whole electricity generator should look like:

-conductor-threshold-antenna-conductor-threshold-

and electrons will more likely go left.

If the antennas are printed, above threshold could be just narrowing.