Heat conversion by using piezzo effect

[andreas_varesi]

Hi Kysmett,

the idea of the patent was to use very small piezzo elements with only some hundred nanometers. Than the local pressure variations should be strong enough to generate a constant current. If you try to rebuild this effect within a larger scale the classical laws of thermodynamics are valid and nothing will happen. Only if you go down to nanometers you can utilize the kinetic theory of gases. And this is exactly the problem for non industrial research - we don't have the possibilities to proof our own theories.

Best regards

Andreas

[Kysmett]

I wonder how one would structure the material...I say material because I see the end product somewhat like velvet.  A flexible fabric sub-structure with tiny, piezo nano hairs on it.  If worn, or flown from a flagpole, you would get more than just ambiant prssure flux....hmmmm... will have to cook on this some more.  Textile manufacture seems to play a large part in my mental picture however.  The remaining question lies thus:  How dificult would it prove to actually make (or grow) some of this stuff on a fabric?

[swankpower]

The Michael Jennsen patent is available to view on the following link

http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=DE19942739&F=0

If there is any trouble downloading it I could post the PDF version.

[andreas_varesi]

Hi Kysmett,

the idea of a velvet like piezo structure sounds very reasonable. But even if you can produce such a material, the next problem is to rectify the alternating voltage. Maybe it is possible to combine piezo hairs with nanotubes that work like an diode. GE is leading in developing such devices http://www.azonano.com/details.asp?articleID=996. Maybe there are also other companies who see a chance in surpassing GEs success with this new idea of combining piezo hairs with nanotubes.

Reagards

Andreas

[swankpower]

The little cells descibed in the patent are evacuated, to make one dimensional pressure, and sealed with an ultrathin membrane. I would think they would only work for a limited spectrum of pressure and gases.


well we know pV=nRT at this 'classical' level. Pressure is dependent on the number of molecules and temperature and independent of the individual molecules size. The heavier the gas we use surrounding the piezo, the slower the gas molecules will travel, communing the same amount of kinetic energy to the walls per second. If we use heavy molecules which are gaseous at room temperature, z.B. Halon gas: Dibromotetrafluoroethane Atomic weight: 259.84, the average velocity of the gas particles is reduced by about three fourths. Lower velocity particles means more time for the piezo to relax back into its resting position, meaning you can use a little larger piezo. Furthermore, if giving the piezo time to relax is an issue, just put fewer molecules surrounding the cells, just enough pressure to push in the piezo.

There are other less reactive refrigerants which could be used, but if you want stability perhaps xenon tetrafluoride, but thats not a household ingredient like refrigerants.

In case you're wondering where I got that three-fourths figure, I used:
1/2*m1*v1^2=1/2*m2*v2^2 to get
v1=v2*(m2/m1)^(1/2)
try m2=16 (oxygen), m1=260(Dibromotetrafluoroethane), v1=.25*v2

Regards,
Andrew