Thermoacoustic applications 5kw/kg

[sigurd]

I just found a thermoacoustic electrical generator.

They say it can achieve 5kw per kg device. The things has only the one moving part, should be utter reliability.

50kw - how can they get any efficiency, transferring all that to that little rod?

However I want to make a hydraulic pump. If you have good ideas about that, please tell.

Also you are invited to add anything related to thermoacoustics.

[sigurd]

Here is an acoustic compressor. More details.

It uses a linear actuator to shake the resonator, creating the standing waves that pumps the gas.

[kistinie]

Thermoacoustic is rather old tech discovered by glass blower that noticed that heated glass was producing some noise

Supaero, a French school for aerospace tech is doing a refrigerator research project based on thermoacoustic : http://thermoacoustic.free.fr/
Another school is doing a musical instrument ! http://thermoacoustique.free.fr/

About conversion of heat in electricity, is this a kind of reverse pelletier effect or just stirling or Carnot Cycle ?

Very nice tech, art, energy and food conservation !!!!

Smart Pangolin !

[sigurd]

Thanks for the links,



The electric conversion is the same as the instrument in your link - heat makes the air oscillate inside a tube/chamber, at the end of this chamber is a "reversed loudspeaker" - IE a huge microphone.

Is it stirling or rankine? I don't know?

I have been looking at Teslas Valvular Conduit, for the purpose of a no moving parts thermo-acoustic compressor.

[sigurd]

Says at the IO site, "The TAC [thermo acoustic cycle] engine is a Carnot engine, in that overall efficiency is governed primarily by the temperature delta across its isothermal heat exchangers, HXh and HXc, i.e.:

n = (T1 - T2) / T1"

[masalai]

Along a similar vein but different application http://www.planetsafepumps.com/ pumps water using water flow - makes a lot of noise but pumps quite a vertical head....

[sigurd]

I like those pumps. I came to think about exciting a resonator with pulsed combustion, ie a modified pulsejet. unless i wanted to pump combusted gases (not the best for actuators), i would then need a means to dump the pressurized flue gas. I then came to think about vortex tubes. A great device. Input pressure, and at one output comes colder, the other one hotter gas. So, would feed back hot flue to the resonator, expelling cold.
The other end of the resonator then, would be breathing in and out the pumped medium, air or water or both.

Then I started thinking about combining the vortex effect with oscillations, to localise the heat inside the combustion chamber. Wings could be put inside a conical or otherwise circular combustion chamber, at speed antinodes, and harness the oscillating motion to make everything spin. It would probably increase the peak pressure along the outside, and decrease the min. pressure along the axis. More head to the compressor/pump, also, one could direct the spinning gas to preferrence according to its radial and axial position - ie send back hot gas toward the combustion and expel cold.

Then I started thinking about a short resonator, with a pulse burner one end, and breathing air and water in the other end, flash boiling the water mist from radiation from the flames, with a wall of clean air between. It could be sucked right into the flames almost, then pushed back out by the oscillations.

[masalai]

Huh?

[sigurd]

shaking, swinging, detonating, injecting and flashing. Sound good? Oh and +190 DB

[masalai]

Ahhhhhh, Is that so - sounds like a bloody effective alarm system, set that off whilst a burgler is inside stealing stuff - burgley is totally disabled and incapacitated blithering wreck...

Brain Fart!!! design one that is highly directional in sound output and sell the concept as an anti pirate device.... Do I get a nice commission fee? - I would really appreciate a couple of hundred thousand AU$...

[sigurd]

190DB is probably several times more than lethal, but the units only make a slight hum, they say.

I wondered about the shape needed to sustain such waves. Cylinders are resonant at harmonics of the base frequency, this apparently makes the high pressure peak overtake the wave troughs, creating shock waves, maybe in the way the sea is calmed by the waves breaking. There is some explanation in the Macrosonix and Fellows patents. Reading US5515684 now. It says,

In order to avoid turbulence at the design conditions the preferred embodiment of the present invention includes resonators having a radius r and an axial coordinate z, where dr/dz is continuous wherever particle velocities are high enough so as to otherwise cause turbulence due to the discontinuity. The preferred embodiment also avoids excessive values of d^2r/dz^2 where particle velocities are high, in order to prevent turbulence which would otherwise occur as a result of excessive radial fluid accelerations.

Problem is, I don't know what the term d is!

Any way, it turns out a simple cone can sustain a pretty strong wave.
Some of these resonators can pump more than 230psi it says.
By using a jet pump, where the motive fluid is taken from the peak pressure, and sucking from ambient pressure, and discharging to the minimum pressure of the resonator, it should boost the head even more.

Massi, there has been some weaponry based on sound, one of them as antipirate device. wikipedia says US military tried to make a portable "smoke ring device" (air bazooka), they made it strong enough to topple a human but the range was not 30m which they required.

In addition to those companies above there is also the Los Alamos TASHE project, they made a travelling wave device for liquefying gas. And penn State university has done some research on thermoacoustics too, they have tested the tesla valvular conduit but I cannot find any more than a reference to that test.

[sigurd]

low freq thermoacoustic / stirling?

1st pic is from US patent 6910332 (Fellows). Claims 63% of Carnot efficiency. Travelling wave.
2nd pic is a pulsed internal combustion electrical generator from pat. 98032216 (Macrosonix)
3rd pic is the formula for the combustion chamber in the 2nd pic, in open office spreadsheet.

[kistinie]

ENECO

ENECO announced in 2006 a shipset able to do electricity with heat...
http://www.presence-pc.com/actualite...energie-20462/

The product was tested with success by independent labs.
Efficency was 30% with 20°C - 400°C gap ( Absolute Maximum is 45% i think)
With much lower gap efficiency goes down to 5%

Since then ...nothing
Even the internet site from eneco.com is dead.


But it seams the original project was moving on for space

http://www.israelvalley.com/news/200...en-electricite


I won't say conspiracy, only this is very strange how new full of promises tech. ...seems to fade away ?
I have asked Lee from FRG about ENENCO...Never heard of this company claiming for 30% efficency and was surprised as for them efficiency is 5% ???

Any info about it ?
(Sorry for the french kinks ;-))

[marshmat]

There was a group in our physics department a year or two ago that got a thermoacoustic refrigerator working. It definitely can be done. The description of their theory and experiment ran to about a hundred pages, though.... the thing may be short on moving parts, but it's a long way from being a simple device.

[kistinie]

Matt

Refrigerator, more generally cooling is an important market, but electricity production is much more universal.

How should we understand this lack of interest for FRG by example looking desperately for money or ENECO claiming for huge success (30% efficiency) in 2006 and then nothing ?