Compressorless Refrigerator!

[pranabjyoti]

On a programme on Discover Channel, where a scientist (part of the Nobel peace prize winning team) has to choose among various new technologies and inventions that will suit a future megapolis and must be eco-friendly. Out of the lot, one invention, a refrigerator, that cools by using sound wave (no compressor, no cooling coils) attracts my attention. I want to know more about the invention and its working principle and requesting other to send me links on net about that paper.
This invention has been prototyped and on camera it has shown its effectiveness. At least the examiner scientist haven't showed any kind of doubt on the working principle of the product. Therefore, though that product may not now reach market but that's real, no question about that.
Thanks in advance for future help.

[Q]

I found this interesting video on youtube about it. It's in German though and only partially subtitled:

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This BBC article (http://news.bbc.co.uk/2/hi/technology/2543085.stm) also explains a bit:


Novel fridge cools with sound

Food could soon be chilled with sound
Some of the coolest sounds in the world are coming out of a laboratory in Pennsylvania.
At the lab, two US researchers are working on ways to use sound to chill food.

They have produced a sonic fridge that converts very loud sounds to directly cool a fridge containing ice cream.

The researchers hope that their work will end reliance on gases that can contribute to global warming.

Louder than rock

The researchers have exploited the fact that sound waves travel by compressing and expanding the gas that they are generated in.

In the 1980s, Scott Backhaus and Greg Swift at the Los Alamos National Laboratory realised that this compression/expansion action could be used to cool and heat metal plates placed in the path of the sound wave.

A temperature gradient can be generated by putting a stack of plates in the right place in a tube in which the sound wave is bouncing around. Some plates in the stack will get hotter and others colder.


The novel fridge will be used to cool ice cream
All it takes to make a refrigerator out of this system is to attach heat exchangers to the ends of the stack.

Now, Matt Poese and Steve Garratt of the Applied Research Laboratory at Penn State University are doing work on a small chiller cabinet that will be used to keep ice cream cool.

The research is being sponsored by ice cream makers Ben & Jerry's and Unilever.

The pair are using enormously loud sounds to keep their chiller cabinet cool.

Humans feel pain when they hear sounds of 120 decibels, a level typically reached next to the speakers at a rock concert.

The sounds pumped through the Penn State fridge reach 173 dB.

Were the fridge ever to crack open, the vast sounds generated within would not escape because the intense noise can only be generated in the pressurised gas locked inside the cooling system.

Prototypes of fully functioning acoustic fridges have already been built and one has even flown on the space shuttle.

The pair are hoping that their work will end reliance on the gases currently used in fridges that can contribute to global warming.

The research could also make refrigerators more reliable because a thermoacoustic fridge has fewer moving parts.

[pranabjyoti]

Ya, after posting I have googled with "thermoacoustic refrigeration" and found some pretty interesting stuff. I now have some idea about sonar compressors.