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Cryogenic bath-type heat exchangers for ultra-pure noble gas applications
Ist Teil von
Journal of instrumentation, 2022-05, Vol.17 (5), p.P05037
Ort / Verlag
Bristol: IOP Publishing
Erscheinungsjahr
2022
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Abstract
Two cryogenic bath-type heat exchangers for ultra-pure noble
gas applications were developed with particular emphasis on noble
gas liquefaction in cryogenic distillation systems. The main
objective was to construct heat exchangers for xenon from materials
that do not emanate radon and that fulfill ultra-high vacuum
standards. Therefore, only high-quality copper and stainless steel
materials were used. Especially, large-area oxygen-free copper fins
with high conductivity in a new design ensure efficient heat
transfer. One bath-type Xe-Xe heat exchanger was designed with a
diameter of 50 cm to achieve a xenon condensing capacity of at
least 100 kg/h. In order to guarantee the necessary heat transfer
between the two xenon reservoirs, this heat exchanger features a
specially manufactured stainless steel flange with a copper plate
welded inside. We first tested our concept on a dedicated bath-type
heat exchanger with a reduced diameter of 30 cm using liquid
nitrogen to liquefy the xenon. A model based on conservative
assumptions such as film boiling on the nitrogen side and film
condensation on the xenon side was developed and applied to
caluclate the expected heat transfer for our design. We were able to
demonstrate an adjustable xenon liquefaction rate of up to 113 kg/h
limited only by our measurement procedure at a cooling efficiency of
(0.98 ± 0.03) for the LN
2
-Xe heat exchanger.