[plug] [OT+link] Novel fridge cools with sound

[Leon Brooks]

    http://news.bbc.co.uk/1/hi/technology/2543085.stm

    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.

    All it takes to make a refrigerator out of this system is to
    attach heat exchangers to the ends of the stack.

    [...]

    The sounds pumped through the Penn State fridge reach 173 dB,
    tens of thousands of times more intense than any rock concert.

    Sounds of 165 dB would cause a person's hair to catch fire
    from the frictional heating caused by air undergoing such
    intense compression and expansion.

    Thankfully, even if the fridge cracks open the vast sounds
    generated within will 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.

Research page here:

    http://www.acs.psu.edu/thermoacoustics.html

FAQ (http://www.acs.psu.edu/THERMO/faq.htm) says:

    At the present time, the efficiency of thermoacoustic
    refrigerators is 20-30% lower than their vapor compression
    counterparts. Part of that lower efficiency is due to the
    intrinsic irreversibilities of the thermoacoustic heat transport
    process. These intrinsic irreversibilities are also the
    favorable aspects of the cycle, since they make for mechanical
    simplicity, with few or no moving parts. A greater part of the
    inefficiency of current thermoacoustic refrigerators is simply
    due to technical immaturity.

Buy one here (they don't mention CPU coolers yet):

    http://www.qdrive.com/

Apparently they've been building the suckers since 1997 and nobody bothered to 
tell the Beeb up to now. (-:

Cheers; Leon