It's Hot, It's Cool, It's Electrifying

[clcuckow]

I found this article while looking for homebrew AC designs.

http://dsc.discovery.com/news/2007/05/25/soundstove_tec.html?category=a nimals&guid=20070525093000

It's some seriously cool technology, I can see that they would be great for the 3rd world as intended but don't you think it would make the ultimate tipi accessory?

[Tengu]

its very good, but would we be able to afford it?

[clcuckow]

its very good, but would we be able to afford it?

They think that once the design is spot on they should be able to do them for £30-40. Don't know if they will do them for the first world for that (they might want to recoop the high R&D from us) but the idea is for them to make a difference in the 3rd so cost of construction is key.

[gregorach]

Now that is a very interesting gadget... I wonder what the overall thermal efficiency is like, and whether it's better than you'd get from a Stirling engine? I'm pretty sure the Stiriling would be more difficult and expensive to produce though...

[JonnyP]

Nice bit of kit, and very clever...

[Spikey DaPikey]

Think im gonna look into these more, as it seems a great idea :)

[clcuckow]

Think im gonna look into these more, as it seems a great idea :)

Just remember that at the moment it is just a University reseach project, but it would be a shame if it did not come to market.

[Gailainne]

It really is an interesting idea, and would be wonderful for the third world if they got it to work, there's a few things I'm unclear about tho;


The heated air begins to vibrate and produce sound waves. Inside the pipes, the noise is 100 times louder than a jet taking off. But because the pipes are stiff and do no vibrate, the sound waves have nowhere to go. So outside the pipe, people hear only a faint hum.
I get the concept, basically how a musical instrument works, but surely it would require either open ends to work, or a closed twin system like a stirling as the air passes between the two hot and cold chambers creates the desired frequency, and warmer the country the less efficient it would be, would'nt it ?

The noise comment has got me a bit stumped as well a stiff metal tube will conduct sound better, would'nt it ? not contain it. Perhaps they have figured out a freq and shape that will contain the sound waves, as per a mirrored ruby laser <shrug>

The big stumper for me though is this comment;

For refrigeration, the heated, compressed air is sent through a different part of the pipe, where sound waves cause the air to expand

Eh ?

If you release compressed air suddenly through a narrow orifice the pressure differential will freeze the water right out of the air (try it with a scuba tank) :(

An air pressure wave, like a thunder storm will produce a sound wave, but I've never heard of the reverse.

gregorach ? you any thoughts on this ?

Really want it to work :bluThinki

Stephen

[Glen]

I get the concept, basically how a musical instrument works, but surely it would require either open ends to work, or a closed twin system like a stirling as the air passes between the two hot and cold chambers creates the desired frequency, and warmer the country the less efficient it would be, would'nt it ?


I'm rather guessing here but maybe a two way whistle ( possibly a high tech reed? )inplace of the piston in a single chamber Stirling engine. Given powered by a wood fire the ambient temperature probably isn't going to be very significant.



The noise comment has got me a bit stumped as well a stiff metal tube will conduct sound better, would'nt it ? not contain it. Perhaps they have figured out a freq and shape that will contain the sound waves, as per a mirrored ruby laser <shrug>


Probably only "stiff" at the tuned frequency of the whistle pitch.



The big stumper for me though is this comment;

" For refrigeration, the heated, compressed air is sent through a different part of the pipe, where sound waves cause the air to expand "

Eh ?

If you release compressed air suddenly through a narrow orifice the pressure differential will freeze the water right out of the air (try it with a scuba tank) :(

An air pressure wave, like a thunder storm will produce a sound wave, but I've never heard of the reverse.


Sound wave are fast changing areas of high and low pressure. As you point out as you lower the presure it gets cooler and as you increase it it gets hotter.
2 things that it might be, you've got a tuned pitch you can design your sound path to set up what's called standing waves this would give hot and cold spots along the length, tap off these with normal heat sinks. You can think of it as 50 degrees average as an sealed system then split this energy so it's all in know spots, say at points along the length it would be 100 and other point zero degrees ( obviously these are not going to be the correct figures but that's an easy to folow example ) then exchange.
or for cold production relesas the pressure directly at points where it's cooler anyway thereby becoming still cooler.



Those are my first guesses anyway.

[clcuckow]

Just a quickie because I am on my smartphone. I read some more stuff on the official SCORE site that if I remember correctly discribed it as like two sterling engines in series with the second one acting as a thermoacoustic cryocooler, with the 'reverse speaker' in the middle.
I will try and find the link tomorrow.

[clcuckow]

http://www.score.uk.com/research/default.aspx

[gregorach]

The big stumper for me though is this comment;

For refrigeration, the heated, compressed air is sent through a different part of the pipe, where sound waves cause the air to expand

Eh ?

If you release compressed air suddenly through a narrow orifice the pressure differential will freeze the water right out of the air (try it with a scuba tank) :(

An air pressure wave, like a thunder storm will produce a sound wave, but I've never heard of the reverse.

gregorach ? you any thoughts on this ?

Really want it to work :bluThinki

Stephen

Ah, now I remember hearing about this when the effect was first discovered a few years back, but I can't remember the details off-hand. But basically, it turns out that very loud noise can be used as a refridgerant - "thermoacoustics". No idea how it works though...

[gregorach]

http://www.score.uk.com/research/default.aspx

Fascinating... I've got a funny feeling I'm not going to get much work done today! ;)

[Gailainne]

Already the engine's 30% efficiency and high reliability may make medium-sized natural-gas liquefaction plants (with a capacity of up to a million gallons per day) and residential cogeneration economically feasible.WOW :eek: