Thermoacoustics

Thermoacoustics is the interaction between temperature, density and pressure variations of acoustic waves. Thermoacoustic heat engines can readily be driven using solar energy or waste heat and they can be controlled using proportional control. They can use heat available at low temperatures which makes it ideal for heat recovery and low power applications. The components included in thermoacoustic engines are usually very simple compared to conventional engines. The device can easily be controlled and maintained.

Thermoacoustic effects can be observed when partly molten glass tubes are connected to glass vessels. Sometimes a loud and monotone sound is spontaneously produced. A similar effect is observed if one side of a stainless steel tube is at room temperature (293 K) and the other side is in contact with liquid helium at 4.2 K. In this case, spontaneous oscillations are observed which are named "Taconis oscillations". The mathematical foundation of thermoacoustics is by Nikolaus Rott. Later, the field was inspired by the work of John Wheatley and Swift and his co-workers. Technologically thermoacoustic devices have the advantage that they have no moving parts, which makes them attractive for applications where reliability is of key importance.