Introduction to Thermoacoustic Engines and Refrigerators

Glassblowers observed the generation of sound in the presence of temperature gradients over one hundred years ago. 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 operated to cool radar equipment for a week on board a US Navy destroyer in 1995. More recently, a heat-driven thermoacoustic device, built by the team at Los Alamos, was used to liquefy natural gas at a rate in excess of 140 gal/day by burning part of the gas stream.