ASA 126th Meeting Denver 1993 October 4-8

2aPAa1. Optimal heat-driven thermoacoustic refrigeration: The beer cooler revisited.

W. Patrick Arnott and par Anthony A. Atchley

Atmos. Sci. Ctr., Desert Res. Inst., P. O. Box 60220, Reno, NV 89506 Physics Dept., Naval Postgraduate School, Monterey, CA 93943

The goals of this research are to design and build an optimally efficient heat-driven thermoacoustic refrigerator to cool a given heat load to a desired temperature. The system uses heat to drive a thermoacoustic prime mover that produces sound for a thermoacoustic refrigerator (as originally investigated by John Wheatley in a device he called a beer cooler on account of the temperatures and heat loads he was striving to obtain). Here, the first step, numerical design, is described. A given system configuration is analyzed using Runge--Kutta integration of three coupled DE's for ambient temperature, acoustic pressure, and specific acoustic impedance (SAI) in the prime mover and refrigerator and using pressure plus SAI transition equations elsewhere. Complex eigenfrequency analysis is used to obtain starting values for a root finding routine for the systems opening acoustic pressure, hot end temperature, heat load, and frequency. Optimization is used to find a system configuration that maximizes overall efficiency. These calculations should shed new insight into optimal heat exchanger lengths. Progress on meeting these goals is reported. The basic set of equations used in the Runge--Kutta integration have intriguing forms and are discussed. Emphasis is placed on investigation of the coupling between prime mover and refrigerator operation. [Work supported by ONR.]