ITS Ultr a-low-Mass Cooling System Pipe Design: Minimum Inner D iameter calculation &

E. Da Riva/M. Gomez Marzoa 1CFD Meeting - 25th January 2013

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

Contents

CFD Meeting - 25th January 2013 2

1. Overview2. Cooling system: constraints3. Cooling concepts

Pipes per stave Operating pressure

4. Pipe Inner Diameter optimization Inner Barrel layers Outer Barrel layers

5. Construction of the tubing Material Erosion constraints U-pipe construction

E. Da Riva/M. Gomez Marzoa


OverviewInner Barrel Outer Barrel

Wound-truss structure.

Wound-truss structure with high-conductivity plate.

Concept for outer layers (4-5, 6-7), based on the high-conductivity plate cooling idea.

x/X0 < 0.3% per layer x/X0 < 0.8% per layer



1. 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. bag @300 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?).

2. 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.

3. 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).

Cooling system: constraints

1 Source: http://emupdates.com/2009/11/25/flow-rates-of-various-vascular-catheters/



1. No prototype performed OK (0.3 W cm-2)2. A last prototype with larger winding angle

will be available for test

Where are we? Inner Barrel

1. Successful proposal (up to 0.5 W cm-2)2. Several prototypes for test:

a) Pipe ID = 1 mmb) Squeezed pipesc) K1100 Plate (λ ~ 1000 W m-1 K-1)



1. Pipe dimensions: Initially: ID = 1.450, OD = 1.514 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.

2. 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). …

Where are we? Inner Barrel



T3

T3

T2 = T1+0.5*ΔTStave

Cooling ConceptsPipes per stave

1 straight pipe along each stave:T1

T2Stave

Stave

T1 U-pipe along each stave:

ΔTRef-Stave = T3-T1


Inner Barrel



Cooling ConceptsOperating 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

1. Water in single-phase or C4F10 two-phase.2. Leak-less or no connectors.3. 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.

Inner Barrel



Pipe Inner Diameter OptimizationWater 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:

Restrictions: Single/U-pipe:

ΔTWater = 3-6 K Lpipe = 0.29-0.58 m

Leak-less/no connectors: ΔpMax-InOut = 0.2-2 bar

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

3. 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

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

4. Water, U-pipe, no connectors:

Inner Barrel



Pipe Inner Diameter OptimizationC4F10 in two-phase

Assumptions: Stave power density = 0.4 W cm-2

ΔxInOut = 0.5 (conservative) xAverage = 0.5 (for Friedel corr.)

5. C4F10, single pipe:


ΔTMax-InOut = 3-6 K ΔpMax-InOut = 0.19-0.37 bar

Lpipe = 0.29-0.58 m

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

6. 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

0.4 0.50 0.58 6.0 0.36 0.99 0.36<0.37

Inner Barrel



Pipe Inner Diameter Optimization Assumptions:


Restrictions: ΔTMax-InOut = 3-6 K Lpipe = 0.29-0.58 m

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 0.58 6.0 2.32 1.06<2.00 0.55

C4F10 ΔxInOut [-] Lpipe [m] ΔTRef [K] m [g s-1] ΔpInOut [bar] ID [mm]

5 Single pipe 0.35 0.29 3.0 0.51 0.10<0.19 1.10


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!

Inner BarrelSUMMARY



Where are we? Outer Barrel

BusSi 0.05mm thick

Kapton, ID=2.794 mm wall = 0.06mm

30.4 mm

Carbon prepreg thick=TBD

Carbon prepreg thick=TBD

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 layer6-7 1475 30 0.4 177.0 <0.8 per layer

Spaceframe

CF Plate



T3

T3

T2 = T1+0.5*ΔTHalf-stave

Cooling ConceptsPipes per stave

1 straight pipe along each half stave:T1

T2Half-stave

Half-stave

T1 U-pipe along each half-stave:


ΔTRef-Half-Stave = T3-T1

Outer Barrel

Stave

Half-stave



Cooling ConceptsOperating 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

1. Water in single-phase or C4F10 two-phase.2. Leak-less or no connectors.3. 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).

Outer Barrel






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

3. Water, U-pipe per half stave, leak-less:

4. Water, U-pipe per half stave, no connectors:

Outer Barrel



L4-5






5. C4F10, single pipe per half stave:



Lpipe = 0.85-1.70 m


0.4 0.35 0.85 3.0 1.59 2.65 0.10<0.19

6. 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

0.4 0.50 1.70 6.0 1.11 2.40 0.36<0.37

Outer BarrelL4-5







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



5 Single pipe 0.35 0.85 3.0 1.59 0.10<0.19 2.65


The minimum pipe diameter is achieved for design number 4: ID=1.71 mm ~ 39% smaller than the ordered 2.794 mm ID.

SUMMARY Outer BarrelL4-5






1,2. Water, single pipe per half stave:





3. Water, U-pipe per half stave, leak-less:

4. Water, U-pipe per half stave, no connectors:

Outer Barrel



L6-7






5. C4F10, single pipe per half stave:



Lpipe = 1.50-3.00 m


0.4 0.35 1.50 3.0 2.78 4.25 0.09<0.19

6. 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

0.4 0.50 3.00 6.0 1.94 3.80 0.36<0.37

Outer BarrelL6-7







1,2 Single pipe 1.50 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



5 Single pipe 0.35 1.50 3.0 2.78 0.09<0.19 4.25


The minimum pipe diameter is achieved for design number 4: ID=2.99 mm ~ 6.5% bigger than the ordered 2.794 mm ID.

SUMMARY Outer BarrelL6-7



Pipe Inner Diameter Optimization

Layer IDMin [mm] Design Refrigerant ΔTRef [K] vH2O [m s-1]

1, 2, 3 0.55U-pipe, no connectors Water 6.0 1.54, 5 1.71

6, 7 2.99

SUMMARY 0.4 W cm-2

MAT. BUDGET CONSIDERATIONS

Achieving the target of 0.3%:1. Use a two-phase flow.2. 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



Construction of the tubing1. 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.

2. 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).


1. General considerations: Robust:

Tensile strength = 117.9 Mpa Flexural Modulus = 4.1 GPa

Thin walls: down to 0.025 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)


Construction of the tubing

Minimum bend radius?

In Vickers, polyimide would have 772 MPa



Construction of the tubing2. Specific requirements:

High radiation hardness: according to CERN-98-01 report, polymide: No problem below 107 Gy Mild damage between 107 to 5 107 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 0.025 mm. PEEK: X0 = 31.45 cm, minimum wall thickness is 0.25 mm.



Construction of the tubing Advantages of a PEEK pipe over polyimide:

Low material budget material. Polyimide: X0 = 29 cm PEEK: X0 = 31.45 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-98-01 report. Wall thickness:

Polyimide minimum wall thickness = 0.025 mm. PEEK minimum wall thickness = 0.25 mm


E. Da Riva/M. Gomez Marzoa 26CFD Meeting - 25th January 2013

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

ITS Ultr a-low-Mass Cooling System Pipe Design: Minimum Inner D iameter calculation &

Documents

pipe erosion

pipe material

pipe integrity

pipe dimensions

pipe id optimization

reduced pipe id prototype

small plastic pipe

gomez marzoacfd meeting