Chapter 81 - Stack and frequency's coupling characteristic analysis in thermoacoustic systems

Abstract

For standing wave thermoacoustic refrigerator, the refrigeration performance depends on the phase departing the phase of standing wave and the resonance being excited, which is a result of coupling between stack and frequency. The performance of a standing-wave thermoacoustic refrigerator system depends on the thermoacoustic stack and frequency modulating phase between the pressure and gas velocity. The quality factor differs for different parameter of stack, so only an effective frequency bandwidth can couple phase to realize heat pumping and excite the resonance. Two fundamental conditions must be satisfied to heat up the temperature gradient in a standing wave thermoacoustic refrigerator: (1) the phase between pressure and velocity can shift from 90, and (2) the resonance can be excited. The phase between pressure and volume is modulated by the crank in a traditional engine. But for a standing wave refrigerator driven by loudspeaker, there is no crank. The stack and frequency modulate phase between the pressure and gas velocity. Because the particular dynamic resource and particular manner of phase modulated, it is important to determine the frequency and stack for the goal. On the other hand, the stack is the core to realize the conversion between heat energy and acoustic power.