Flow Pattern Analysis for Oscillatory Flow inside Resonator Tube for Thermoacoustic Refrigerator Using PIV Measurement

Abstract

A thermoacoustic refrigerator system is an alternative cooling system that uses air or inert gas as acooling fluid. The environmentally friendly characteristics make this system potential as a green alternative for acooling system. However, due to its low efficiency compared to conventional vapor compression systems, itsapplication is limited. Since a thermoacoustic refrigerator is based on the oscillatory flow to generate a coolingeffect, the understanding of a flow pattern inside the resonator tube is crucial to enhance the coefficient ofperformance (COP) of the system. In this study, Particle Image Velocimetry (PIV) is used to visualize the flowpattern inside the resonator tube. PIV is an optical, noninvasive technique that uses a high-speed camera, highpower multipulse laser, and synchronizer to capture the particle movement in the resonator with a length of 1 m,and the frequency applied is 100 Hz. The result shows that there is a formation of a vortex at the entrance and atthe exit of the stack. The formation of the vortex at the entrance induces by the flow disturbance created by thestack. This vortex formation varied with the location of the stack and the amplitude of the wave applied. Thevelocity distribution of the particle inside the resonator tube is also presented and discussed in this paper. Thesefindings indicate that the flow patterns and velocity distribution should be further analyzed to interpret the effectof these characteristics on the system. These results are expected to give a better understanding of the futuredevelopment of the thermoacoustic system.