Theoretical and experimental study of thermoacoustic engines

Thermoacoustic engines can be used to pump heat using a sound wave (refrigerator or heat pump) or pump a sound wave using a temperature gradient (prime mover). The basic arrangement is a gas-filled acoustic resonator with appropriately positioned thermoacoustic elements. Two types of thermoacoustic elements are used in these engines. The first type are heat exchanges which are used to communicate heat between the gas and external heat reservoirs. The second type is the thermoacoustic engine (TAE), also known as a stack. The TAE's are sections of porous media that support the temperature gradient, the transport heat on the acoustic wave between the exchangers, and that produces or absorbs acoustic power. Previous theoretical results in thermoacoustics have been developed for TAE's with circular or parallel slit pore geometries. We have developed a general linear formulation for gas-filled TAE's having pores of arbitrary cross-sectional geometry. This analysis, which is very helpful in designing optimal engines, indicates the parallel slit pore geometry optimizes heat and work flow.