Performance measurement of a mini thermoacoustic refrigerator and associated drivers

Abstract

A miniature Thermoacoustic refrigerator is being developed to cool integrated circuits - which must sometimes operate at high temperatures nearing the upper threshold of their tolerance - to temperature spans more within the circuits' tolerable limits, without the need of the chemicals of a traditional refrigerating system. The development of an electrically powered acoustic driver that powers the thermoacoustic refrigerator is described, as well as different schemes to improve its delivered acoustic power. The driver utilizes a flexural tri-laminar piezoelectric disk to generate one to two Watts of acoustic power at 4 kHz in 15 bar of He-Kr gas mixture. Two different drivers are tested on a pressurized test resonator, and their quantitative performance is analyzed. The analysis of the drivers' performance indicates one power-improvement scheme may be faulty, while data taken before the second broke indicates its design may be beneficial to power-improvement. Tests are also conducted using a refrigerating resonator; these first attempts to meet design criteria of temperature span and cooling power are unsuccessful, but the results obtained - including a thermodynamic coefficient of performance (COP) 13.1% below the modeled ideal value for the given data set - with less-than-ideal acoustic power delivered to the resonator signal suggest continued research is worthwhile.