ASA 126th Meeting Denver 1993 October 4-8

2aPAa4. Thermodynamic performance of a high-power thermoacoustic refrigerator.

David K. Perkins D. Felipe Gaitan Richard Russell Ashok Gopinath L. Todd Morris James A. Mayfield Steven L. Garrett

Phys. Dept. and Space Systems Academic Group-Code Sp/Pk, Naval Postgraduate School, Monterey, CA 93943

The cooling capacity of a high-power thermoacoustic refrigerator that uses resonant high-amplitude sound in inert gases to pump heat will be measured and discussed. The thermoacoustic engine under study utilizes two thermoacoustic drivers each capable of delivering 60 W of acoustic power at 325 Hz. The engine is designed to deliver 205 W (700 BTU/h) of useful cooling capacity at 4 (degrees)C (refrigerator mode) and 117 W (400 BTU/h) at -22 (degrees)C (freeze mode). The engine includes two ``stacks'' with heat exchangers at each end. Using differential thermopiles, the temperature difference across the inlet and outlet of each of the four heat exchangers is combined with the fluid mass flow rate to quantify heat flow. The determination of the acoustic power delivered to the resonator, combined with the heat flows, forms a complete set of thermodynamic measurements which permits accurate determination of the thermoacoustic coefficient-of-performance. These measurements allow optimization of fluid flow rates. [Work supported by NASA---Life Science Division, the NPS Direct Funded Research Program and the Rolex Award for Enterprise.]