Stack/Heat-Exchanger Research for Thermoacoustic Heat Engines.

The goal of this project is to develop novel configurations of heat pumping elements and heat exchangers for thermoacoustic heat engines. The approach will be to use anisotropic systems employing innovative technology. This approach will allow a heat exchange fluid to flow directly across the heat pumping element of the thermoacoustic heat engine the stack, eliminating the necessity of separate heat exchangers and possibly improving efficiency. During the past year a radically new design, which is robust using only stainless steel and epoxy, relatively easy to fabricate, and employs a filament array or pin stack, has been developed. The pin-stack elements are being made commercially, and other parts have been fabricated for testing the system in the Space Thermoacoustic Refrigerator of S. L. Garrett.