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'Sonic' or 'thermoacoustic' refrigeration is a technology that uses high-amplitude sound waves in a pressurized gas to pump heat from one place to another.

Contents

Operation

Efficiency

Major Event(s)

See also

Notes

References

External links

Operation

This type of refrigerator has no ozone-depleting or toxic coolant and has few moving parts.
A device consisting of a series of small parallel channels, referred to as a ‘stack’, is fixed in place at a set location inside the tube. In a standing wave thermoacoustic engine, the pressure and velocity fluctuations through the stack are such that heat is given to the oscillating gas at high pressure and removed at low pressure; this satisfies Rayleigh’s criterion^[1] for self-sustained oscillation and by this process heat is converted into acoustic power. For thermoacoustic pumps, the process is reversed. By using thermal delays in the stack, this process approximates the highly-efficient Stirling Cycle, but without the cranks, sliding seals or excess weight found in Stirling engines (Ceperley 1979).
Modern research and development of thermoacoustic systems is largely based upon the work of Rott (1980) and later Steven Garrett, and Greg Swift (1988), in which linear thermoacoustic models were developed to form a basic quantitative understanding, while some commercial interest has resulted in niche applications such as small to medium scale cryogenic applications.

Efficiency

The most efficient thermoacoustic devices built to date have a relative Carnot (COPr) efficiency approaching 40%, which is comparable with domestic vapour compression systems and in most cases superior to automotive internal combustion engines.

Major Event(s)

The most recent attempt at commercializing a thermoacoustic refrigerating device was by Ben and Jerry's who employed the researchers at Penn State to test and develop a working prototype to be unveiled at Earth day 2004.

See also

★ Vortex tube

★ Magnetic refrigeration

Notes

1. Not in the sense of angular resolution: See The explanation of certain acoustical phenomena, Lord Rayleigh, , , Nature (London), 1878

References

★ A pistonless Stirling engine – the travelling wave heat engine, Ceperley, P., , , J. Acoust. Soc. Am., 1979

★ A cascade thermoacoustic engine, Gardner, D. & Swift, G., , , J. Acoust. Soc. Am., 2003

★ Thermoacoustics, Rott, N., , , Adv. Appl. Mech., 1980

★ Thermoacoustic engines, Swift, G.W., , , J. Acoust. Soc. Am., 1988

External links

★ Los Alamos National Laboratory, New Mexico, USA

★ Penn State University, USA

★ The Power of Sound, ''American Scientist Online''

★ Thermoacoustics at the University of Adelaide, Australia

★ Discussion Forum

★ How to build a demonstration model for less than $25

★ Clever Fellows Innovation Consortium

★ Ben & Jerry's