Status of Numerical simulation of thermal flow processes in saturated and supercritical helium

1
Status of Numerical simulation of thermal - flow
processes in saturated and supercritical helium
CERN/AT
Slawomir Pietrowicz, Maciej Chorowski
Wroclaw University of Technology, Poland
with collaboration
Rob van Weelderen
CERN, Geneva, Switzerland
2
Content
CERN/AT

• The description of task
• The status of comparison of numerical results
  with the analytical formulas for heat transfer in
  supercritical helium
• Experimental equipment at WUT - present state and
  tentative program
• Conclusions

3
Description of task
CERN/AT
The forms of Helium in superconducting magnets
4
Description of task
CERN/AT
5
Description of task
CERN/AT
At present

• the CFD comparison of experimental correlations
  for different Nusselt numbers in supercritical
  and saturated helium is in progress
• In cases where the heat transfer data is missing
  or multiple data sources are conflicting suitable
  experiments should be envisaged.

6
The review of correlations of Nusselt number for
supercritical helium
Tw temperature of wall Tb temperature of helium

• kinematic viscousity b bulk, w - wall

Hess, H.L., Kunz, H.R. J Heat Trans 87, 41 (1965)
7
Comparison calculations - assumptions

• During the comparison calculations it was
  assumed
• THe - inlet temperature of helium is 4 K
• PHe inlet pressure of helium is 3 bars
• Tw temperature of wall is constant and equals
• Tw THe DT
• D diameter of pipe is 5 mm

Geometry and conditions applied during
calculations
8
Comparison calculations
CERN/AT
Comparison of various modes of helium heat
transfer for the same inlet parameters (The 4
K, Tw TheDT, Re106)
There is no significant difference up to DT 2
K. At higher DT tests will be needed.
Where K thermal conductivity
9
Experimental equipment
CERN/AT
The vacuum container was assembled and leak
tested in May 2006. The insert was assembled and
leak tested in June 2006. The instrumentation was
verified August 2006 The functional performance
of the complete system was done August 2006.
10
Experimental equipment and plan
CERN/AT

• Operational March 2007
• Measurement subjects
• 1) missing heat transfer parameters for CDF code
• 2) Proposal for characterisation of alternative
  cable wrapping schemes under discussion with CERN

11
Conclusions

• The implementation of CFX Code for saturated and
  supercritical helium has been finished.
• The validation of code is under development.
• Fabrication, measurement instrumentation and
  testing of the cryostat has been done. Available
  for experiments March 2007.
• Code validation outcome needs to provide
  motivation for dedicated experiment at WUT.
• Proposal for characterisation of alternative
  cable wrapping schemes under discussion with CERN.