1. Pipe Design: Minimum Inner Diameter calculation
ITS Ultra-low-Mass Cooling System
Pipe Design:
Minimum Inner Diameter calculation
&
Constructive Considerations
Enrico DA RIVA
Manuel GOMEZ MARZOA
CFD Meeting - 25th January 2013
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

2. CFD Meeting - 25th January 2013
Contents
Overview
Cooling system: constraints
Cooling concepts
Pipes per stave
Operating pressure
Pipe Inner Diameter optimization
Inner Barrel layers
Outer Barrel layers
Construction of the tubing
Material
Erosion constraints
U-pipe construction
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

3. CFD Meeting - 25th January 2013
Overview
Inner Barrel
Outer Barrel
x/X0 < 0.3% per layer
x/X0 < 0.8% per layer
Wound-truss structure.
Concept for outer layers (4-5, 6-7), based on the high-conductivity plate cooling idea.
Wound-truss structure with high-conductivity plate.
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

4. Cooling system: constraints
Refrigerant maximum velocity:
Avoiding failure by erosion.
Minimizing pressure drop.
No specific recommendations found for such small plastic pipe:
ASHRAE Handbook: not exceeding 1.5 m s-1 would minimize effects of erosion.
Catheters use similar pipes and materials.
8.5 French gauge catheter (2.8 mm OD, ~1.5 mm ID) cordis/introducer 1.
Max. flow rate: 126 mL min-1 = 7.56 L h-1 = 1.18 m s-1
Max. flow rate w/ p. mmHg: 333 mL min-1=19.98L h-1 = 3.1 m s-1
Damage by erosion in a plastic pipe could be roughly estimated by assessing the material hardness and compared to that of a regular copper pipe (but degradation?).
Admissible pressure drop:
Single-phase cooling: depends on the cooling system design.
Two-phase cooling: must be kept low to ensure the minimum ΔTSat across stave.
Admissible ΔTRefrigerant across stave:
Related to stave temperature uniformity.
In a two-phase cooling system, should not decrease a lot (risk of going below dew point).
1 Source:
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

5. CFD Meeting - 25th January 2013
Where are we?
Inner Barrel
Successful proposal (up to 0.5 W cm-2)
Several prototypes for test:
Pipe ID = 1 mm
Squeezed pipes
K1100 Plate (λ ~ 1000 W m-1 K-1)
No prototype performed OK (0.3 W cm-2)
A last prototype with larger winding angle will be available for test
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

6. CFD Meeting - 25th January 2013
Where are we?
Inner Barrel
Pipe dimensions:
Initially: ID = 1.450, OD = mm
Reason: winding CF around pipe without breaking it (wound-truss structure).
Used as well for the wound-truss structure with high conductivity plate.
Pipe ID could be reduced from the refrigerant viewpoint (water/C4F10).
Constructively possible in High-conductivity plate prototype!
Reduced pipe ID prototype: ID = 1.024, OD = 1.074mm: TO BE TESTED!!
Pipe ID optimization: consider:
Different cooling system layouts.
Refrigerants.
Pipe erosion.
Pipe material:
So far: only polyimide (Kaption®) has been taken into consideration and used for the construction of prototypes.
Concerns:
Pipe integrity?
Mechanical stiffness? (in case of making the U-bend without connectors). …
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

7. CFD Meeting - 25th January 2013
Cooling Concepts
Inner Barrel
Pipes per stave
1 straight pipe along each stave: T1 T2
Stave
ΔTRef-Stave = T3-T1
Stave T3
U-pipe along each stave: T1
T2 = T1+0.5*ΔT
Stave
ΔTRef-Stave = T3-T1 T3
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

8. CFD Meeting - 25th January 2013
Cooling Concepts
Inner Barrel
Operating pressure
Water in single-phase flow:
Leak-less mode (p<1 bar): Δp at stave must be kept low!
No connectors: pMax and Δp limited by pipe strength.
C4F10 in two-phase:
Main limitation is ensuring ΔTSat < ΔTSat-Admissible across the stave.
Current design options
Water in single-phase or C4F10 two-phase.
Leak-less or no connectors.
Single pipe or U-pipe per stave.
6 possible designs.
4 with water
2 with C4F10
Goal: assess the minimum pipe diameter for each of these designs.
Assuming reasonable operating conditions and respecting constraints.
Comparing with experimental results.
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

9. Pipe Inner Diameter Optimization
Restrictions:
Single/U-pipe:
ΔTWater = 3-6 K
Lpipe = m
Leak-less/no connectors:
ΔpMax-InOut = bar
Inner Barrel
Water in single-phase
Assumptions:
Stave power density: 0.4 W cm-2
Water maximum velocity: 1.5 m s-1
1,2. Water, single pipe:
q [W cm-2]
Lpipe [m]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
ΔpInOut [bar]
ID [mm]
0.4
0.29
3.0
4.65
1.35
0.10<0.20
1.22
Water, U-pipe, leak-less:
q [W cm-2]
Lpipe [m]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
ΔpInOut [bar]
ID [mm]
0.4
0.58
6.0
2.32
0.83
0.18<0.20
0.99
Water, U-pipe, no connectors:
q [W cm-2]
Lpipe [m]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
ΔpInOut [bar]
ID [mm]
0.4
0.58
6.0
2.32
1.50
1.06<2.00
0.55
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

10. Pipe Inner Diameter Optimization
Inner Barrel
C4F10 in two-phase
Restrictions:
Single/U-pipe:
ΔTMax-InOut = 3-6 K
ΔpMax-InOut = bar
Lpipe = m
Assumptions:
Stave power density = 0.4 W cm-2
ΔxInOut = 0.5 (conservative)
xAverage = 0.5 (for Friedel corr.)
C4F10, single pipe:
q [W cm-2]
ΔxInOut [-]
Lpipe [m]
ΔTRefrig [K]
m [g s-1]
ID [mm]
ΔpInOut [bar]
0.4
0.35
0.29
3.0
0.51
1.10
0.10<0.19
C4F10, U-pipe:
q [W cm-2]
ΔxInOut [-]
Lpipe [m]
ΔTRefrig [K]
m [g s-1]
ID [mm]
ΔpInOut [bar]
0.4
0.35
0.58
6.0
0.51
1.13
0.35<0.37
0.50
0.36
0.99
0.36<0.37
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

11. Pipe Inner Diameter Optimization
Inner Barrel
SUMMARY
Restrictions:
ΔTMax-InOut = 3-6 K
Lpipe = m
Assumptions:
Stave power density: 0.4 W cm-2
Water
vH2O [m s-1]
Lpipe [m]
ΔTRef [K]
m [L h-1]
ΔpInOut [bar]
ID [mm]
1,2
Single pipe
1.35
0.29
3.0
4.65
0.10<0.20
1.22 3
U-pipe, leak-less
0.83
0.58
6.0
2.32
0.18<0.20
0.99 4
U-pipe, no connectors
1.50
1.06<2.00
0.55
C4F10
ΔxInOut [-]
m [g s-1] 5
0.35
0.51
0.10<0.19
1.10 6
0.35<0.37
1.13
The minimum pipe diameter is achieved for design number 4:
ID=0.55 mm ~ 62% smaller than current 1.45 mm ID!
Refrigerant material budget (i.e. water) is 7 times lower!
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

12. CFD Meeting - 25th January 2013
Where are we?
Outer Barrel
Layer
LStave [mm]
Si width [mm]
q [W cm-2]
Q per stave [W]
x/X0 [%]
4-5
843 30
0.4
101.2
<0.8 per layer
6-7
1475
177.0
Spaceframe
Kapton, ID=2.794 mm wall = 0.06mm
Carbon prepreg thick=TBD
CF Plate
Carbon prepreg thick=TBD
Si 0.05mm thick
Bus
30.4 mm
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

13. ΔTRef-Half-Stave = T3-T1
Cooling Concepts
Outer Barrel
Pipes per stave
1 straight pipe along each half stave: T1 T2
Half-stave
ΔTRef-Stave = T3-T1
Half-stave T3
Stave
U-pipe along each half-stave: T1
Half-stave
T2 = T1+0.5*ΔT T3
ΔTRef-Half-Stave = T3-T1
Half-stave
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

14. CFD Meeting - 25th January 2013
Cooling Concepts
Outer Barrel
Operating pressure
Water in single-phase flow:
Leak-less mode (p<1 bar): Δp at stave must be kept low!
No connectors: pMax and Δp limited by pipe strength.
C4F10 in two-phase:
Main limitation is ensuring ΔTSat < ΔTSat-Admissible across the stave.
Current design options
Water in single-phase or C4F10 two-phase.
Leak-less or no connectors.
Single pipe or U-pipe per stave.
6 possible designs.
4 with water
2 with C4F10
Goal: assess the minimum pipe diameter for each of these designs.
Assuming reasonable operating conditions and respecting constraints.
Comparing with experimental results (not yet).
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

15. Pipe Inner Diameter Optimization
Restrictions:
Single/U-pipe:
ΔTWater = 3-6 K
Lpipe = m
Leak-less/no connectors:
ΔpMax-InOut = bar
Outer Barrel
Water in single-phase
Assumptions:
Stave power density: 0.4 W cm-2
Water maximum velocity: 1.5 m s-1
L4-5
1,2. Water, single pipe per half stave:
q [W cm-2]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
Lpipe [m]
ΔpInOut [bar]
ID [mm]
0.4
3.0
14.50
1.40
0.85
0.09<0.20
3.66
Water, U-pipe per half stave, leak-less:
q [W cm-2]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
Lpipe [m]
ΔpInOut [bar]
ID [mm]
0.4
6.0
7.25
1.25
1.70
0.18<0.20
2.05
Water, U-pipe per half stave, no connectors:
q [W cm-2]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
Lpipe [m]
ΔpInOut [bar]
ID [mm]
0.4
6.0
7.25
1.5
1.70
0.32<2.00
1.71
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

16. Pipe Inner Diameter Optimization
Outer Barrel
C4F10 in two-phase
Restrictions:
Single/U-pipe:
ΔTMax-InOut = 3-6 K
ΔpMax-InOut = bar
Lpipe = m
L4-5
Assumptions:
Stave power density = 0.4 W cm-2
ΔxInOut = 0.5 (conservative)
xAverage = 0.5 (for Friedel corr.)
C4F10, single pipe per half stave:
q [W cm-2]
ΔxInOut [-]
Lpipe [m]
ΔTRefrig [K]
m [g s-1]
ID [mm]
ΔpInOut [bar]
0.4
0.35
0.85
3.0
1.59
2.65
0.10<0.19
C4F10, U-pipe per half stave:
q [W cm-2]
ΔxInOut [-]
Lpipe [m]
ΔTRefrig [K]
m [g s-1]
ID [mm]
ΔpInOut [bar]
0.4
0.35
1.70
6.0
1.59
2.75
0.36<0.37
0.50
1.11
2.40
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

17. Pipe Inner Diameter Optimization
Outer Barrel
SUMMARY
Restrictions:
ΔTMax-InOut = 3-6 K
Lpipe = m
Assumptions:
Stave power density: 0.4 W cm-2
L4-5
Water
vH2O [m s-1]
Lpipe [m]
ΔTRef [K]
m [L h-1]
ΔpInOut [bar]
ID [mm]
1,2
Single pipe
1.40
0.85
3.0
14.50
0.09<0.20
3.66 3
U-pipe, leak-less
1.25
1.70
6.0
7.25
0.18<0.20
2.05 4
U-pipe, no connectors
1.50
0.32<2.00
1.71
C4F10
ΔxInOut [-]
m [g s-1] 5
0.35
1.59
0.10<0.19
2.65 6
0.36<0.37
2.75
The minimum pipe diameter is achieved for design number 4:
ID=1.71 mm ~ 39% smaller than the ordered mm ID.
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

18. Pipe Inner Diameter Optimization
Restrictions:
Single/U-pipe:
ΔTWater = 3-6 K
Lpipe = m
Leak-less/no connectors:
ΔpMax-InOut = bar
Outer Barrel
Water in single-phase
Assumptions:
Stave power density: 0.4 W cm-2
Water maximum velocity: 1.5 m s-1
L6-7
1,2. Water, single pipe per half stave:
q [W cm-2]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
Lpipe [m]
ΔpInOut [bar]
ID [mm]
0.4
3.0
25.40
1.50
0.09<0.20
5.98
Water, U-pipe per half stave, leak-less:
q [W cm-2]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
Lpipe [m]
ΔpInOut [bar]
ID [mm]
0.4
6.0
12.70
1.10
3.00
0.19<0.20
4.08
Water, U-pipe per half stave, no connectors:
q [W cm-2]
ΔTWater [K]
m [L h-1]
vH2O [m s-1]
Lpipe [m]
ΔpInOut [bar]
ID [mm]
0.4
6.0
12.70
1.50
3.00
0.47<2.00
2.99
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

19. Pipe Inner Diameter Optimization
Outer Barrel
C4F10 in two-phase
Restrictions:
Single/U-pipe:
ΔTMax-InOut = 3-6 K
ΔpMax-InOut = bar
Lpipe = m
L6-7
Assumptions:
Stave power density = 0.4 W cm-2
ΔxInOut = 0.5 (conservative)
xAverage = 0.5 (for Friedel corr.)
C4F10, single pipe per half stave:
q [W cm-2]
ΔxInOut [-]
Lpipe [m]
ΔTRefrig [K]
m [g s-1]
ID [mm]
ΔpInOut [bar]
0.4
0.35
1.50
3.0
2.78
4.25
0.09<0.19
C4F10, U-pipe per half stave:
q [W cm-2]
ΔxInOut [-]
Lpipe [m]
ΔTRefrig [K]
m [g s-1]
ID [mm]
ΔpInOut [bar]
0.4
0.35
3.00
6.0
2.78
4.35
0.35<0.37
0.50
1.94
3.80
0.36<0.37
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

20. Pipe Inner Diameter Optimization
Outer Barrel
SUMMARY
Restrictions:
ΔTMax-InOut = 3-6 K
Lpipe = m
Assumptions:
Stave power density: 0.4 W cm-2
L6-7
Water
vH2O [m s-1]
Lpipe [m]
ΔTRef [K]
m [L h-1]
ΔpInOut [bar]
ID [mm]
1,2
Single pipe
1.50
3.0
25.40
0.09<0.20
5.98 3
U-pipe, leak-less
1.10
3.00
6.0
12.70
0.19<0.20
4.08 4
U-pipe, no connectors
0.47<2.00
2.99
C4F10
ΔxInOut [-]
m [g s-1] 5
0.35
2.78
0.09<0.19
4.25 6
0.35<0.37
4.35
The minimum pipe diameter is achieved for design number 4:
ID=2.99 mm ~ 6.5% bigger than the ordered mm ID.
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

21. Pipe Inner Diameter Optimization
SUMMARY
0.4 W cm-2
Layer
IDMin [mm]
Design
Refrigerant
ΔTRef [K]
vH2O [m s-1]
1, 2, 3
0.55
U-pipe, no connectors
Water
6.0
1.5
4, 5
1.71
6, 7
2.99
MAT. BUDGET CONSIDERATIONS
Achieving the target of 0.3%:
Use a two-phase flow.
Minimize pipe diameter to reduce the impact of the refrigerant to the global material budget.
BUT need to keep thermal contact between Si and pipe!
Constructive issues when ↓ID
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

22. Construction of the tubing
General considerations:
Robust: elastic modulus, high burst pressure.
Thin walls: reduce mat. budget.
Compatible with refrigerant (C4F10).
Easy to bend: in case of making a no-connector stave, limited space.
Erosion: related to the material hardness.
Specific requirements:
High radiation hardness: minimum damage.
Ageing: physical and chemical stability over time.
Comply to LHC Fire Safety Instruction (IS-41)
Low material budget material (plastics better than metals).
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

23. Construction of the tubing
General considerations:
Robust:
Tensile strength = Mpa
Flexural Modulus = 4.1 GPa
Thin walls: down to mm for a pipe with 0.55 mm ID
Compatible with refrigerant (C4F10): yes
Easy to bend:
Must avoid kinking failure: when section deforms to an elliptical shape.
A reinforcement braid can be included locally to prevent kinking.
Braid: SS or others, Covered with Nylon, Pebax…
Flexible liners like Nitinol (Ni + Ti) or Kevlar could reinforce the tube to be bent and preserve the shape (shape memory).
Erosion: related to the material hardness.
Polyimide/PEEK: 87D (Shore D)
PVC Pipe: 89D (Shore D)
Copper: 372 Mpa (Vickers)
Minimum bend radius?
In Vickers, polyimide would have 772 MPa
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

24. Construction of the tubing
Specific requirements:
High radiation hardness: according to CERN report, polymide:
No problem below 107 Gy
Mild damage between 107 to Gy
1st layer of ITS Inner Barrel will be exposed to 700 krad/yr.=7000 Gy/yr.
Ageing: physical and chemical stability over time.
Plastic Pipe Institute states corrosion is not an issue in plastic pipes.
Comply to LHC Fire Safety Instruction (IS-41)
Polyimide is allowed.
Nylon® (polyamide) is allowed if a fire retardant NOT containing halogen, sulphur or phosphorus.
Pebax: polyether block amides – “legal” in cavern??
Low material budget material (plastics better than metals).
Polyimide: X0 = 29 cm, minimum wall thickness is mm.
PEEK: X0 = cm, minimum wall thickness is 0.25 mm.
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

25. Construction of the tubing
Advantages of a PEEK pipe over polyimide:
Low material budget material.
Polyimide: X0 = 29 cm
PEEK: X0 = cm
The U-turn can be shaped and retain the shape.
Extremely stable.
More common in scientific applications than polyimide tubing.
Advantages of a polyimide pipe over PEEK:
Higher radiation hardness: according to CERN report.
Wall thickness:
Polyimide minimum wall thickness = mm.
PEEK minimum wall thickness = 0.25 mm
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013

26. Pipe Design: Minimum Inner Diameter calculation
ITS Ultra-low-Mass Cooling System
Pipe Design:
Minimum Inner Diameter calculation
&
Constructive Considerations
Enrico DA RIVA
Manuel GOMEZ MARZOA
CFD Meeting - 25th January 2013
E. Da Riva/M. Gomez Marzoa
CFD Meeting - 25th January 2013