CERN Accelerating science

Internal Note
Report number	LHC-PROJECT-NOTE-191
Title	Thermo - hydraulic analysis of a cryogenic jet: application to helium recovery following resistive transitions in the LHC
Author(s)	Chorowski, M ; Grzegory, P ; Konopka, G
Submitted by	[email protected] on 3 Jun 1999
Subject category	Accelerators and Storage Rings
Accelerator/Facility, Experiment	CERN LHC
Free keywords	Cryogenic jet ; Thermo-hydraulic analysis
Abstract	A resistive transition (quench) of the LHC sector magnets will be followed by cold helium venting to a quench buffer volume of 2000 m3 at ambient temperature. The volume will be composed of eight medium-pressure (2 MPa) gas storage tanks made of carbon steel, which constrains the temperature of the wall to be higher than -50 oC (223 K). Possible spot cooling intensity and thermo-mechanical stresses in the tank wall following helium injection have been analysed previously and the aim of the present study is experimental verification of basic assumptions concerning cryogenic jet parameters and heat transfer between jet crown and tank wall. For this purpose jet diameter, velocity profile and convective heat transfer between jet and steel plate have been measured. A simple jet model description based on momentum conservation has been proposed. Then, the lowest possible temperature of the tank wall which may occur has been assessed.