He II heat exchanger test unit for the LHC inner triplet
The Inner Triplet Heat Exchanger Test Unit (IT-HXTU) is a 30-m long thermal model designed at Fermilab, built in US industry, fully automated and tested at CERN as part of the US LHC program to develop the LHC Interaction Region quadrupole system. The cooling scheme of the IT-HXTU is based on heat exchange between stagnant pressurized He II in the magnet cold mass and saturated He II (two-phase) flowing in a heat exchanger located outside of and parallel to the cold mass. The purposes of this test are, among others, to validate the proposed cooling scheme and to define an optimal control strategy to be implemented in the future LHC accelerator. This paper discusses the results for the heat exchanger test runs and emphasizes the thermal and hydraulic behavior of He II for the inner triplet cooling scheme.
A He II heat exchanger test unit designed for the LHC interaction region magnets
The LHC interaction region (IR) inner triplets are cooled with stagnant pressurized He II at 1.9 K. All heat loads deposited in the pressurized He II bath will be carried away by saturated He II via a He II heat exchanger. The heat exchanger, made from a corrugated copper tube inside a stainless steel pipe, will be placed outside of and parallel to the cold mass in the cryostat. The current paper details the design work of a full scale He II heat exchanger test unit for the verification of LHC inner triplet magnet cooling system.
Pressure drop from flow of cryogens in corrugated bellows
Abstract The pressure drop experienced by cryogenic fluids flowing through corrugated bellows is investigated up to Re = 4 × 10 6 . The measured pressure drop is seen to increase approximately as the square of the velocity. Comparison of N 2 gas, LN 2 and He II pressure drop results indicates that there is no fundamental difference between the behaviour of classical fluids and turbulent He II in bellows systems. The present results are analysed with only limited success in terms of existing correlations for pressure drop in bellows. One finding is that the classical friction factor appears to increase slightly with Reynolds number, which is consistent with the behaviour of the drag coefficient measured in similar geometrical configurations.