Thermoacoustic heat engine
![A schematic representation of a thermoacoustic hot-air engine. The Heat exchanger (heat bridge not shown) has a hot side which conducts heat to or from a hot heat reservoir – and a cold side (cold bridge not shown) that conducts heat to or from a cold heat reservoir. The electro-acoustic transducer, e.g. a loudspeaker, is not shown.](/Images/godic/202502/16/Thermo-acoustic_cooling_machine4345.png")
Thermoacoustic engines (sometimes called "TA engines") are thermoacoustic devices which use high-amplitude sound waves to pump heat from one place to another, or conversely use a heat difference to induce high-amplitude sound waves. In general, thermoacoustic engines can be divided into standing wave and travelling wave devices. These two types of thermoacoustics devices can again be divided into two thermodynamic classes, a prime mover (or simply heat engine), and a heat pump. The prime mover creates work using heat, whereas a heat pump creates or moves heat using work. Compared to vapor refrigerators, thermoacoustic refrigerators have no ozone-depleting or toxic coolant and few or no moving parts therefore require no dynamic sealing or lubrication.