Experimental study on thermoacoustic refrigerators driven by a travelling-wave thermoacoustic engine

A thermoacoustic engine is a new type of pressure-wave generator that possibly has a very long lifetime because of no mechanical moving parts. A thermoacoustic engine operating in standing wave mode is also called a natural engine with intrinsic thermodynamic irreversibility, so it shows a poor thermodynamic performance in converting thermal energy to acoustic energy. The conversion efficiency is around 10 to 25 percent of Carnot. By analyzing the generation rate of acoustic workflow and the local critical temperature gradient in the traveling-wave and standing wave modes, a thermoacoustic engine with local traveling-wave loop was designed, built and studied. In addition, a miniature coaxial pulse tube refrigerator was attached to the engine, and about 80K temperature difference was achieved with nitrogen in preliminary tests.