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End-cap Mechanics FDR Cooling Structures. Steve Temple, RAL. 1 November 2001. End-Cap Disc Services Cooling Structures. Full details - See ATL-IS-ER-0021 Cooling Circuit Layout 3 circuits per quadrant - corresponding to inner, middle and outer module rings

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end cap mechanics fdr cooling structures

End-cap Mechanics FDRCooling Structures

  • Steve Temple, RAL

1 November 2001

CLRC

end cap disc services cooling structures
End-Cap Disc ServicesCooling Structures
  • Full details - See ATL-IS-ER-0021
  • Cooling Circuit Layout
    • 3 circuits per quadrant - corresponding to inner, middle and outer module rings
    • 3 separate Inlets, 3 outlets are manifolded at patch panel
    • Outer and middle module Circuits - Two point cooling
    • Inner module circuit - Single point cooling
    • Bend radii (inner) kept to 5 times OD i.e. 18.7 mm
  • Cooling Component Materials/Joining Techniques
    • C-C cooling blocks
    • CuNi pipe - 3.6mm ID, 70 µm Wall
    • Cu plating (sputter coat + electroplate) of cooling blocks enables soft soldering to cooling pipe

CLRC

slide3

End-Cap Disc ServicesCooling Structures

  • Mechanical Requirements
    • Position modules to a positional tolerance of 134 microns (diameter) in the R-phi direction, for one module relative to its neighbour
    • Provide co-planar mounting surfaces for modules
    • Minimise forces transferred to the support structure i.e. carbon fibre disc
    • Operational for 10 years
    • Lowest possible mass
  • Thermal Requirements
    • To ensure the highest temperature of any part of the silicon on a module doesn’t exceed -7 °C

CLRC

slide4

End-Cap Disc ServicesCooling Structures

  • Cooling Pipe Circuit Design
    • CuNi material chosen for its excellent resistance to corrosion, and its excellent solderability
    • ‘Wiggly’ pipe Layout reduces forces on disc from thermal contractions and pipe manufacturing tolerance
      • Thermal Contraction Forces

Forces calculated using an FE model, using following material properties and boundary conditions :

E=152 GPa, = 12e-6/K, T=50K

      • Pipe Manufacturing Tolerances

Deviation of pipe bend centres from nominal positions kept to a minimum, through tooling design

In addition stress relieving of manufactured circuits is proposed - testing is planned in next round of prototyping

CLRC

slide8

End-Cap Disc ServicesCooling Structures

  • Cooling Pipe Prototyping
    • First prototype - Inner cooling circuit for system test
    • Old circuit design - Internal bend radii of 14mm
    • Ice used as filler material
    • Custom made pipe bender designed and manufactured
    • Manufactured at RAL

CLRC

slide9

End-Cap Disc ServicesCooling Structures

  • Cooling Pipe Prototyping (Cont’d)
    • Second prototype - Single U shaped bend
    • Internal bend radii of 20mm - 5 x OD
    • Cerobend used as filler material
    • Swaged ends - enables low mass joining of pipes
    • Manufactured by established pipe bending company

CLRC

slide10

End-Cap Disc ServicesCooling Structures

  • Cooling Block Design
    • Primary Cooling Block

Thermal Design

      • C-C material chosen for good thermal conductivity - 300 W/m2K (fibre direction), 50 W/m2K (transverse direction)
      • Fibre orientation optimised
      • Straight split corresponding to hybrid and silicon
      • Further details see thermal performance

Mechanical Design

      • Machined module location boss
      • Planar module mounting surface wrt block mounting surface
      • Accurate cooling block height

CLRC

end cap cooling structures cooling block design
End-Cap Cooling StructuresCooling Block Design
  • Cooling Block Design (Cont’d)
    • Second Point Cooling Blocks

Thermal Design

      • C-C material chosen for good thermal conductivity - 300 W/m2K (fibre direction), 50 W/m2K (transverse direction)
      • Fibre orientation optimised

Mechanical Design

      • As primary cooling block
    • Second Point Mounting Blocks

Thermal Design

      • No thermal requirements - Made from low mass PEI polymer

Mechanical Design

      • As primary cooling block

CLRC

end cap cooling structures cooling block design1
End-Cap Cooling StructuresCooling Block Design
  • Cooling Block Prototyping
    • Two prototyping exercises (old and current design)
    • Several manufactured, metrology checked to assess ability to machine key features within appropriate tolerances
      • 3mm OD location boss
      • Parallelness between bottom and top surfaces
      • Block height dimension

CLRC

end cap disc services cooling structures1
End-Cap Disc ServicesCooling Structures
  • Cooling Block Prototyping (Cont’d)
    • Current cooling block design metrology results
    • Improvements to design for machining operations simplification identified

CLRC

end cap disc services cooling structures2
End-Cap Disc ServicesCooling Structures
  • Joining of C-C Blocks to Cooling Pipe
    • Soldering of cooling blocks to pipe
      • Good thermal joint
      • Good mechanical joint - Soldered joint sample (using swaged end) undergone helium vacuum leak test
      • Standard SnPb (60/40) solder with non-corrosive Castolin 197 flux.
      • Requires Cu plating of C-C block
    • Cu Plating of C-C Blocks
      • Plating trials show good adhesion to C-C base material achieved by :

Cleaning, Cu Sputtering, Cu Electroplating and Au Flash (to prevent copper oxidisation)

      • 15 micron Cu plating followed by 2 micron Au flash

CLRC

end cap disc services cooling structures3
End-Cap Disc ServicesCooling Structures
  • Cooling Structure Precision Assembly
    • To achieve positional tolerances required a precision assembly technique is performed during the disc services to disc assembly stage
    • This involves a precision rotary stage (r-phi) and an alignment arm (providing radial position)
    • Details see ATL-IS-ER-0022

CLRC

end cap disc services cooling structures4
End-Cap Disc ServicesCooling Structures
  • Cooling Structure Precision Assembly (Cont’d)
    • Blocks are required to be positioned in r-phi with a positional tolerance of 66 microns - Out of 134 micron error budget
    • Results show this is readily achievable using this method

CLRC

end cap disc services cooling structures5
End-Cap Disc ServicesCooling Structures
  • Thermal Performance
    • Extensive prototype testing and thermal simulation carried out on the Baseline Design (see ATL-IS-ER-0009)
      • Full cooling quadrant (3 circuits) manufactured and tested on evaporative cooling rig
      • Dummy thermal module mounted on sector and tested
      • Successfully demonstrated a coolant temperature of -20 to -22 °C was sufficient to keep the inner module below -7 °C.
      • Design consisted of Aluminium Alloy cooling blocks joined to Aluminium cooling pipes.
      • Effect of material changes therefore need to be assessed

CLRC

end cap disc services cooling structures6
End-Cap Disc ServicesCooling Structures
  • Thermal Performance (Cont’d)
    • Assessment of cooling block material change
      • C-C block substituted into the simulation. Again boundary conditions - 4000 W/m2K @ -20C (7.5 W, 1W)
      • Minimal change on silicon side. Better performance on hybrid side.

Al Tsil=-11.5°C

C-C Tsil=-11.3°C

Al THyb=-6.9°C

C-C THyb=-8.4°C

CLRC

end cap disc services cooling structures7
End-Cap Disc ServicesCooling Structures
  • Thermal Performance (Cont’d)
    • Assessment of cooling pipe material change
      • Reduction in thermal conductivity and wall thickness results in reduction of convective heat transfer area.
      • However as htc increases with heat flux, this effect will be decreased.
      • Small scale prototype testing on an evaporative C3F8 cooling rig is planned

CLRC