An Hybrid Cycle Helium Liquefier
A simple and robust helium liqufier has been developed at CEA / SBT. It is a Collins type liquefier operated at atmospheric pressure in a standard commercial helium dewar. To increase reliability, the liquefaction circuit and the refrigerator are separated. Precooling and condensation temperature are provided by an hybrid closed cycle mechanical cryocooler: a commercial Gifford Mc Mahon cryocooler (Cryomech GB 37) is used as a precooler for helium gas to be liquefied and for the Joule Thomson expansion circuit (4.5 W at 4.5 K).
The liquefaction circuit is designed to admit low purity helium. A prototype of this liquefier has been successfully operated for 6 months with a typical liquefaction rate of 1.1 liter per hour.
KeywordsHeat Exchanger Pneumatic Valve Cryogenic Engineer Liquefaction Rate Cycle Refrigerator
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