Experimental study of a heat-driven/solar thermoacoustic refrigerator

Abstract

This work reports the design and testing of a prototype thermoacoustic refrigerator optimized by the code DeltaE. The key functional feature of this quarter-wavelength resonator is its dual power input capability electric heating elements and the sun. These can be utilized independently or complimentarily to benefit all-weather operation. The machine operates near 270 Hz with helium (60%)–argon (40%) mixture at two bars mean pressure. Heat from either heat source is transported from the high-temperature end to the prime mover stack via thin copper plates that also serve as the hot-end heat exchanger. Both stacks utilize an uncoated automobile catalytic converter ceramic structure with 1.3-mm cell-to-cell square openings and 74% porosity. The ceramic structure provides a strong and easy-to-implement stack with minimal heat conduction. Both middle- and cold-end heat exchangers use simple copper fin design, with the middle heat exchanger using circulating water cooling. DeltaE results predict a 30<th>°C temperature drop across the heat pump stack at no-load condition with 30 W heating, 363<th>°C across the prime mover stack (work=4.0 W) and pressure fluctuation level equal to 6.2%. Results from the effects of working fluid, changing pressure, heating temperature, and cooling load will be discussed.