헬륨을 냉매로 사용한 열음향 냉동기의 제작 및 성능평가

Abstract

The thermoacoustic refrigerator has not only considerable possibility but also commercial usability, because it has high reliability, lower vibration, no moving part, and can be easily constructed. In this study, a thermoacoustic refrigerator using a resonant standing acoustic wave has been built. It employs a loudspeaker to sustain a standing wave in a resonance tube. The resonator type 1/2 wavelength thermoacoustic refrigerator is designed and fabricated according to the method suggested by Hofler.

The apparatus is capable of driving closed systems containing helium at mean pressures ranging from 1-6 bar. The resonance tube is 1040mm in length, theoretical resonance frequency of which is about 465Hz.

But the actual resonance frequency is observed to be 476Hz. The resonator type 1/2 wavelength thermoacoustic refrigerator is composed of a resonator of 40mm diameter, stack of plates, heat exchangers and speaker driver. The thickness of the hot heat exchanger and the cold heat exchanger is 10mm, 6mm respectively.

The stack of plates made of Kapton(Mylar) is of spiral type having finite spaces of 0.6mm. The length of the stack of plates is 80mm.

The maximum temperature drop obtained in the experiment is observed to be 39.3°C when it is driven at 476Hz and 120W of speaker power.

The cold-part temperature of the exchanger falls to -18.3°C. The COP relative to Carnot's cycle has its maximum of 2.47% when the speaker is driven at 50W.