Design aspects of the resonator for a thermoacoustic cryocooler

Abstract

The resonator is an important component of a thermoacoustic compressor, since its working frequency and profiles of pressure and velocity are significantly influenced by its geometry and dimensions. The performance of pulse tube cryocooler driven by thermoacoustic compressor greatly depends on the resonator design. As the optimal operating frequencies of the pulse tube cryocooler and thermoacoustic compressor are quite different, one way to overcome this mismatch is by the proper design of the resonator. The frequency of thermoacoustic compressor depends on the resonator length and the acoustic speed. As the acoustic speed is constant for a particular working fluid the way to decrease the frequency is by elongation of resonator length. A resonator component provides the inertances and compliances needed to store acoustic energy and shifts the amplitude or the phase of oscillating pressure or volume flow rate. But inertance is also accompanied by viscous resistances and compliances or thermal relaxation resistances, with both resistances dissipating acoustic power. This paper explores the design analysis of the system with emphasis on the resonator as part of the thermoacoustic drive. The influence of different parameters on resonance frequency as well as the acoustic power of thermoacoustic compressor should be taken into account while designing the resonator. © 2010 American Institute of Physics.