# Presentation: 171052

## Inner Triplet Cryogenics and Heat Transfer

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

## 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

## 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.

## 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.

## 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

## 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.

## 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.

## 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.

## IR Cryo Studies – FY06 Q1 Milestone

- Assumes first stage cold compressors are moved closer to the IR’s, reducing the pressure-induced temperature drops.
- Allocates the largest T’s 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.

## IR Cryo Studies – FY06 Q1 Milestone

|  | Temperature range [K] | T [mK] |
| --- | --- | --- |
| Magnet bore annular space to heat exchanger crossover pipe | 2.150-2.000 | 150 |
| Heat exchanger crossover pipe | 2.000-1.950 | 50 |
| Heat exchanger crossover pipe to heat exchanger (saturated side) | 1.950-1.826 | 124 |
| Pressure drop along the inner triplet heat exchanger | 1.826-1.816 | 10 |
| Pressure drop through the J-T heat exchanger shell | 1.816-1.791 | 25 |
| Pressure drop through piping to the first stage cold compressor | 1.791-1.716 | 75 |

## 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.

## 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

## 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.

## Comparison of current and upgraded Q1-Q2a interconnects.

- IR Cryo Studies – FY06 Q2 Milestone

## Calculated size of each HX crossover pipe.

- IR Cryo Studies – FY06 Q2 Milestone

## IR Cryo Studies – FY06 Q2 Milestone

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

## 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.

## IR Cryo Studies – Add’l 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.

## 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.

## 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.

## 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

## 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.

## IR Cryo Studies – FY07 Budget

- Requested budget is identical to that of FY06.

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