Date of Award
Master of Science (MS)
Mechanical & Aerospace Engineering
Ayodeji O. Demuren
Sushil K. Chaturvedi
Helium refrigeration at temperatures below 4.5-Kelvin (K), but greater than 0.8-K typically employ a sub-atmospheric process utilizing a vacuum pumping system. These types of helium refrigerators are of keen interest to present and future particle physics programs utilizing super-conducting magnet or radio-frequency technology. As such, there is a need for small scale 2-K helium refrigeration systems (i.e., those that operated below the lambda temperature) in small laboratories and test facilities at this time. This study establishes the key process parameter choices of flow ratio, heat-exchanger size, and supply pressure, and how they influence the overall system performance for various process configurations that do not utilize rotating machinery within the cold box (i.e., turbo-machinery for either cryogenic vacuum pumping or expansion) but do utilize a separate commercially available 4.5-K helium liquefier system. Three 2-K process configurations are studied to determine the key process parameter values that yield the best performance. These process configurations are compared to the commonly employed (but inefficient) direct vacuum pumping process, which typically uses a dewar as the 4.5-K liquid helium supply source. It is found that the performance of these configurations is similar and substantially superior to direct vacuum pumping, providing an inverse coefficient of performance of around 1800 W/W.
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Knudsen, Peter N..
"Process Study for the Design of Small-Scale 2 Kelvin Refrigeration Systems"
(2008). Master of Science (MS), Thesis, Mechanical & Aerospace Engineering, Old Dominion University, DOI: 10.25777/2S45-TV78