How to Design a Thermoacoustic System Considering the Relaxation Time τ: Introduction of Parameter ωτ to Determine the Position of Stack

Abstract

Experimental investigations were carried out to establish a design method for a thermoacoustic cooling system. When a straight acoustic tube is used, the acoustic power is supplied from the tube end. The ceramic stack, which consists of many narrow channels, is inserted into the tube. By changing the insertion position and the stack channel radius, a temperature decrease at the stack end is observed as the energy conversion parameter. A nondimensional parameter, ωτ, considering the relaxation time τ is determined from resonance frequency and stack channel radius. The temperature decrease is examined using several values of ωτ. Results show that the insertion position for which the maximum temperature decrease is obtained depends on ωτ. Therefore, the best stack insertion position can be designed according to the given frequency and stack channel radius. For that reason, ωτ is an important index for thermoacoustic cooling systems.