Speaker
Description
The acoustic expander is an innovative cryogenic component that uses gaseous pressure waves for work transfer as part of a continuous flow, recuperative cycle refrigerator. This expander uses passive reed-valves coupled to an acoustic resonator, much like a wind instrument, to produce refrigeration. The passive reed-valves are pressure-controlled by the imposed, static pressure difference across the expander and the natural oscillating pressure in the resonator. The resonator is a series of tubes and cones, the geometry of which has been optimized with numerical modeling. The practical implications of these simple components are that the acoustic expander does not require controlled valving or close-tolerance sliding seals at low-temperature, unlike existing piston- or turbo-expanders. This work presents new improvements to these first-of-a-kind acoustic expanders including the use of a single-frequency, numerically optimized resonator that allows for operation at an expansion pressure-ratio greater than 2 while maintaining competitive isentropic efficiencies above 50%. This prototype operates with compressed air working fluid and delivers cooling powers of around 100 Watts at room temperature. These expanders are expected to be useful in medium-scale refrigeration applications that are not well served by current small-scale Stirling cryocoolers or large-scale turbo-expander refrigerators.
DISTRIBUTION STATEMENT A. Approved for public release. Distribution is unlimited.
This material is based upon work supported by the Department of the Air Force under Air Force Contract No. FA8702-15-D-0001. Any opinions, findings, conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Department of the Air Force.
| Submitters Country | United States of America |
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