Abstract: This paper first briefly introduces the basic working principle and technical features of thermoacoustic technology, points out that the thermoacoustic technology (including thermoacoustic heat engines and refrigerators) based on thermoacoustic effects has the obvious advantages of high reliability and environmental friendliness due to free of moving mechanical parts and using of inert working gas. Then, the important milestones in the research of the thermoacoustic technology in the recent decades are summarized, mainly including the researches of thermoacoustic heat prime movers and thermoacoustic refrigerators. In regard to thermoacoustic heat prime movers, the paper first gives a brief review of the discovery history of the two kinds of thermoacoustic effects: thermally-induced sound and acoustical-induced refrigeration effects, as well as the research progress in the standing-wave thermoacoustic heat engines. Successively, the suggestion of traveling-wave thermoacoustic heat engine concept and its rapid developments are presented in more detail. Among the important advancements, the researches on the thermoacoustic-Stirling heat engine (TASHE) with a 30% thermoacoustic conversion efficiency and on the energy-focused TASHE with a maximum pressure ratio over 1.3 (with helium as working gas) and a 32% thermal efficiency are highlighted. In the aspect of thermoacoustic refrigerators, several researches on thermoacoustically driven pulse tube cryocooler for achieving cryogenic cooling below 120 K and thermoacoustic room-temperature refrigerators for achieving higher efficiency and large cooling power are reported. In particular, the thermoacoustically-driven two-stage pulse tube cryocooler capable of reaching a lowest temperature below 20 K by using a so-called acoustical pressure amplifier and the heat-driven double thermoacoustic-Stirling refrigerator achieving 300 W at –20℃ with higher efficiency are emphatically introduced. Finally, this paper also gives a brief review of the advancement of thermoacoustic theory, discusses the key scientific and technical issues of the current thermoacoustic technology, and forecasts the future development trends of thermoacoustic technology.

Key words: el., Energy-focused resonator, High efficiency and environmental friendliness, Research advance, Standing/traveling wave, Thermoacoustic heat engines/refrigerators, Thermoacoustic technology, Thermoacoustic-Stirling