Thermoacoustics speaks up at ASA convention

Thermoacoustic devices convert heat directly into intense sound waves with relatively high efficiency—reportedly 40% of Carnot-cycle efficiency. (A Carnot cycle employs the principles of the Carnot Theorem, which states that a cycle continuously operating between a low temperature and a high temperature can be no more efficient than a reversible cycle operating between the same temperatures.) Physicists can use the thermoacoustic effect simply to cool a system by converting its wasted heat to sound, which they can then convert to electrical energy by focusing the sound on a piezoelectric device.

A number of papers at last month's Acoustical Society of America Conference in Salt Lake City suggested progress in all of these areas. Papers described the construction and optimization of the thermal-sound generators and the energy-capture devices that went with them.