Inner Triplet Cryogenics and Heat Transfer

1
Inner Triplet Cryogenics and Heat Transfer

• LARP Collaboration Meeting Berkeley, CA
• April 25-28, 2006

2
IR Cryogenics Studies Outline

• Task goals and milestones
• Task status toward these goals and milestones
• Plans for the remainder of FY06
• FY06 task budget status
• Preliminary FY07 technical plan and milestones
• Preliminary FY07 task budget request

3
IR Cryo FY06 Task Goal

• Task goal To support an LHC luminosity upgrade,
  investigate and compare 2 K inner triplet
  cryogenic systems and coil temperatures for
  single-bore quadrupole-first designs. Analytical
  studies will also be conducted to investigate IR
  quadrupole cryostat quench protection issues
  related to stored energy, pipe sizes, and
  material thicknesses.

4
IR Cryo FY06 Task Milestones

• FY06 Q1 Establish and document a design
  temperature profile for an upgraded IR.
• Study possible LHC cryo system modifications to
  determine how much additional temperature drop
  can be gained for the IR.
• Based on these results, arrive at a design heat
  load. Iteration with magnet designers and
  analysts may be necessary.
• Portion the temperature drop appropriately within
  the IR in preparation for parametric studies.

5
IR Cryo Studies FY06 Task Milestones

• FY06 Q2 IR quad heat transfer parametric
  studies using the design temperature profile,
  including
• Conductor cooling
• Heat exchanger design
• Pipe sizing

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IR Cryo Studies FY06 Milestones

• FY06 Q3
• IR quad cryostat quench protection studies
• Estimate maximum quadrupole quench pressures
  based on sizes of cooling channels and piping
• Calculate required material thicknesses based on
  maximum quench pressure
• IR triplet heat transfer parametric studies
• Expand on IR quadrupole parametric studies to
  investigate heat transfer issues in the inner
  triplet.

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IR Cryo Studies FY06 Milestones

• FY06 Q4 IR triplet quench protection studies
• Expand on IR quadrupole parametric studies to
  investigate quench protection issues in the inner
  triplet.

8
IR Cryo Studies FY06 Q1 Milestone

• With input from CERN cryo personnel, an upgraded
  IR design temperature profile was documented
  (LARP-doc-100) (milestone completed). This
  temperature profile
• Assumes the inner triplet must be kept in He II
  with a heat load of 1.2 kW (Mokhov and Rakhno).
• Assumes a cold compressor upgrade, from 15 mbar
  to 12 mbar. This makes available an additional
  60 mK of temperature drop.

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IR Cryo Studies FY06 Q1 Milestone

• Assumes first stage cold compressors are moved
  closer to the IRs, reducing the pressure-induced
  temperature drops.
• Allocates the largest DTs to potential
  bottlenecks, keeping in mind the most
  advantageous temperature range for He II heat
  transport (1.8-2.0 K).
• Maximum He II conductivity at approx. 1.8-2.0 K.
• Cold mass cooling channel sizes are limited.
• Crossover pipes from cold mass to HX are
  potential bottlenecks due to high heat fluxes.
• HX is a potential bottleneck, especially if only
  a fraction of the wall is wetted for He II heat
  transfer. This effect will depend on the final
  HX configuration.

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IR Cryo Studies FY06 Q1 Milestone
11
IR Cryo Studies FY06 Q2 Milestone

• From heat deposition calculations (Mokhov and
  Rakhno), the Q1 non-IP end is the limiting
  location for the inner triplet cryo.

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IR Cryo Studies FY06 Q2 Milestone

• Based on the design temperature profile,
  parametric studies have been performed for
  several cold mass characteristics
• HX crossover pipe
• Longitudinal cooling channels in the cold mass
• Radial cooling channels in the yoke and collar
• Beam pipe annulus

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IR Cryo Studies FY06 Q2 Milestone

• Additional HX crossover pipes between the cold
  masses and the heat exchanger are required to
  minimize He II conduction lengths and heat flux
  per pipe.
• Seven HX crossover pipes are envisioned one
  pipe at each end of every cold mass with the
  exception of one pipe between Q2a and Q2b.

14
IR Cryo Studies FY06 Q2 Milestone

• Comparison of current and upgraded Q1-Q2a
  interconnects.

15
IR Cryo Studies FY06 Q2 Milestone

• Calculated size of each HX crossover pipe.

16
IR Cryo Studies FY06 Q2 Milestone

• Typical results of cold mass parametric study (Q1
  non-IP end).

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IR Cryo Studies FY06 Q2 Milestone

• HX conceptual design is a shell and tube heat
  exchanger (pressurized He II in tubes) and a
  separate pumping line.

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IR Cryo Studies Addl FY06 Q2 Work

• Cryogenics of not only the inner triplet must be
  considered when the luminosity is upgraded, but
  also the cryogenics of the entire LHC.
• Updated machine heat load estimates for
  short-bunch and long-bunch luminosity upgrade
  scenarios are being generated.

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IR Cryo Studies FY06 Q2 Milestone

• Milestone is not yet achieved.
• Documentation of parametric studies in progress.
• Documentation of machine heat load studies in
  progress.
• Documentation of HX conceptual design in
  progress.
• Detailed HX calculations and documentation
  required, as is documentation of the estimated
  coil temperature.

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IR Cryo Studies Remaining Milestones

• Work associated with the FY06 Q3 and Q4
  milestones is not yet underway.
• It is expected that the FY06 Q2 (quad heat
  transfer studies) and FY06 Q3 milestones (triplet
  heat transfer studies, quad quench protection)
  will be completed in FY06. The FY06 Q4 milestone
  (triplet quench protection) will likely not be
  completed in FY06.

21
IR Cryo Studies FY06 Budget

• Task labor budget 67k
• BNL 20k
• FNAL 47k
• At the end of FY06 Q2
• BNL has spent 21 of its labor budget
• FNAL has spent 38 of its labor budget

22
IR Cryo Studies FY07 Plans

• Possible FY07 milestones
• FY07 Q1-Q2
• Triplet quench protection studies.
• Heat transfer parametric studies of other 2 K
  systems, such as double-bore or dipole-first.
• FY07 Q3-Q4
• Heat exchanger and internal absorber design
  studies.
• Heat transfer parametric studies of 4 K systems.
• Proposal for HX/absorber experimental work.

23
IR Cryo Studies FY07 Budget

• Requested budget is identical to that of FY06.

24
Temperature vs. longitudinal position at the Q1
non-IP end for a range of collar radial cooling
channel sizes.