Thermodynamic cycles executed in a looped-tube thermoacoustic engine (L)

A looped-tube thermoacoustic engine is composed of only a stack of plates, across which a steep temperature gradient is furnished. In spite of the absence of any mechanical parts like pistons and valves, the energy conversion from heat flow into acoustic power flow is performed in the stack. The thermoacoustically induced acoustic field was observed through the simultaneous measurements of pressure and velocity of the working gas, and the thermodynamic cycle executed in the stack was studied. The experimental results show that the acoustic field is tuned without any external forces so as to realize the efficient thermodynamic cycles as possible.