Half a croissant, on a plate, with a sign in front of it saying '50c'
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Human powered thermoacoustic refrigeration
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(+7, -1)
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A sonic heat pump efficiently converts either a temperature differential into a sound, or vice versa. with no moving parts. I'll briefly explain the sound-to-cooling application; for more detail see [link]

An acoustic standing wave induced at the resonant frequency in a tube creates a kind of pistonless Stirling cycle engine, moving heat from one end of the tube to the other in a low pressure working gas (ie air).

Conventional heat exhangers (ie heatsinks, fluid-filled tubes, etc) at the hot and cold ends extract heat from, or dump unwanted heat into, the system as required. The cold end can thus provide refrigeration.

What else is tubular and has a near-constant resonant standing wave droning through it? A didgeridoo.

So combine the two and viola - human powered heating/cooling.

A suitably insulated, tuned mouthpiece is attached to the end of a sonic heat pump. Teams of meditating, circular-breathing hippies take shifts keeping the wave standing, and the vital malaria vaccine (or beer) at the other end cold.

BunsenHoneydew, Feb 05 2009

Sonic heat pump http://en.wikipedia...ustic_refrigeration
No, really [BunsenHoneydew, Feb 05 2009]

(?) Manually Powered Refrigerator Manually_20Powered_20Refrigerator
[FlyingToaster]'s inspiring prior work [BunsenHoneydew, Feb 05 2009]


       [+] {+} :)
FlyingToaster, Feb 05 2009

       You forgot another option. The drone pipe on a bagpipe is almost tailor made for this.   

       I'd personally love to see a performance by the Highland Pipe and Refrigeration band.
MechE, Feb 06 2009

       If only beer cured malaria.   

       //you haven't accidentally created a second use for bagpipes//
I was unaware that there was even a first.
coprocephalous, Feb 06 2009

       In practice warm, moist air would not work for this, and I believe the end of the pipe has to be sealed to produce a temperature gradient. I don't think a high pressure is particularly required, although it probably does increase the power transfer, and thus the heat transfer.

       So the sound generating tube on neither instrument would actually work. On secondary tubes with a diaghpram mounted to the sound generating tube, however...
MechE, Feb 06 2009


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