ENGS 89/90 Reports

Year of Graduation

2025

Project Advisor

Harold Frost

Instructor

Solomon Diamond

Document Type

Report

Publication Date

2025

Abstract

Recuperators are valuable components in refrigeration-cycle devices as they move heat between separate stages within the cycle, lessening the work done by compressors and improving the overall efficiency of the device. For Creare, a Hanover-based engineering firm and our sponsor, a recuperator must be designed to accommodate a mixed-gas flow at cryogenic temperatures. However, upon condensation, mixed-gas becomes a two-phase stream giving rise to heat exchange inefficiencies as the two phases separate and behave thermally distinctly. One way to address this is by incorporating a large surface area porous metal into the recuperator body to remix the two phases into one homogeneous stream and increase thermal contact with the other stream. In this project, we explored this solution by designing, fabricating, and testing a heat exchanger with porous aluminum interstitial section. A two-phase flow of water/air was used to examine stream remixing while water/steam was employed to test heat transfer. Our initial prototype was constructed pragmatically and achieved a lower NTU efficiency than a brazed-plate recuperator used as control, but we observed a notably high interface heat transfer coefficient ultimately indicating a feasible prototype. Research on other materials for use as the porous interstitial was also conducted and the benefits of sintered over un-sintered metals were considered. Finally, we gave recommendations to Creare on future design and implementation cases for their device. This work, which is focused on furthering cooling technology, could have potential use in the aerospace, healthcare, and energy sectors.

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