Condensed Matter Seminars

The interaction of heat and sound has been a subject of interest to scientists and engineers since 1816 when Laplace corrected Newton's attempt to derive the speed of sound in air from first principles. Glassblowers observed the generation of sound in the presence of temperature gradients even earlier. It was less than twenty years ago that the reverse process - the use of high-amplitude sound to produce refrigeration - was first demonstrated. Due to the discovery of the "hole-in-the-ozone" and the ratification of the Montreal Protocols, research in "thermoacoustics" has accelerated during the past decade. In 1992, an electrically-powered thermoacoustic refrigerator was placed in orbit on the Space Shuttle and a larger thermoacoustic chiller for shipboard electronics was demonstrated for a week on board a US Navy destroyer in 1995. More recently, a heat-driven thermoacoustic device was used to liquefy in excess of 100 gal/day of natural gas by burning part of the gas stream. This presentation will include a simple description of the thermoacoustic heat pumping process and will describe some of the novel devices that have exploited this process.