Thermoacoustics.

[CanadaGlass]

I have been lampworking borosilicate glass for a living for over sixteen years. Every once in a while I have a piece of glass start "singing", sometimes quite loudly. Eventually, I learned this is an example of what are called Sondhauss oscillations. And so I was exposed to the topic of thermoacoustics, or the interplay of heat and sound.

A quick forum search found no mention of it, and I thought I would introduce it to some of you.

The most commercially viable application of this emerging technology is refrigeration. Regular vapour compression refrigeration is compressing a gas, letting it dissipate the heat, and then decompressing it, allowing it to absorb heat. A sound wave is just a fluctuating pressure wave, so it too has the ability to pump heat, with no moving parts other than the sound wave itself. Sounds cool? (forgive me) Praxair is doing it to liquify natural gas. Ben and Jerry's use it to make ice cream. Liquifying oxygen, nitrogen, and other cryogenic liquids. The list goes on.

If you are looking to learn more, here is a good place to start:

http://www.lanl.gov/thermoacoustics/

If you are looking for the world leaders in this technology, I would say it is these folks:

http://www.qdrive.com/

[CanadaGlass]

In order to bump this thread, and hopefully breathe some life into it, I thought I would link to a company that has yet to bring any products to market, but is doing research and looking for investors. I can't help but have my doubts...

http://www.io.com/~frg/

[Gord_in_Toronto]

Hi CG!

I was one of the 70+ people who read your OP,

I did check the urls you provided and thought, "That's interesting."

Just in case you think no one is interested. ;)

[Andrew Wiggin]

Basically what you've got going is a sterling cycle with a high frequency. The vibration drives the working fluid back and forth past a heat exchanger, and the expansion and contraction as the working fluid absorbs and releases heat amplifies the vibrations.

The Rijke tube is another example, similar to the Sondhauss tube but with both ends open, and the Rijke tube is more clearly a thermoacoustic refrigerator in reverse.

A