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Enrico DA RIVA (EN-CV-PJ) Manuel GOMEZ MARZOA (EN-CV-PJ) 28 th March 2012. ITS Upgrade: Cooling analysis progress. Contents. St. Petersburg mechanical layout proposal Gas cooling scheme Cooling solution-analysis CFD studies Mechanical analysis ( Corrado Gargiulio ) Optimization

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slide1
Enrico DA RIVA (EN-CV-PJ)

Manuel GOMEZ MARZOA (EN-CV-PJ)

28thMarch 2012

ITS Upgrade:Cooling analysis progress

ALICE ITS - WG4 Meeting - 28th March 2012

contents
Contents
  • St. Petersburg mechanical layout proposal
    • Gas cooling scheme
    • Cooling solution-analysis
    • CFD studies
    • Mechanical analysis (CorradoGargiulio)
    • Optimization
  • CFD-Team Air Cooling proposal
  • Cooling from the ends proposal

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg gas cooling scheme
St. Petersburg gas cooling scheme
  • CFD-Team: asked to analyze the performance of this solution

Total per 3 layers: x/X0=0.94% (all services included)

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg gas cooling scheme1
St. Petersburg gas cooling scheme

Air INLET

D=1.5 mm (variable)

H=0.2-0.3 mm (variable)

Air flow into the shells and out through small holes to Si sensors.

Si sensor ~ 50 µm

Array of holes (OUTLET)

D=0.35 mm

Array pitch = 5 mm

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal analysis
St. Petersburg proposal analysis

MAIN TARGET

Detector Thermal requirements:

  • Detector working temperature = 30 °C
  • Power density = 0.3 - 0.5 W/cm2
  • TAIR-INLET = +14 °C (minimum +7 °C – dew point)

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal analysis1
St. Petersburg proposal analysis

Basic energy balance:

Max. air flow rate predicted in the Technical note: 1.2 l/s

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal analysis2
St. Petersburg proposal analysis

Empirical correlations for round nozzle (single or array): Martin [1], Popiel [2], Goldstein [3]

Not applicable (out of range)

Cooling solution can be modeled as an array of impinging jets:

CFD can predict the HTC for the proposed geometry

  • Considering:
  • A single nozzle. Uniform distribution of air among nozzles.
  • N nozzles per stave = 152 (1stlayer), 152 (2nd), 160 (3rd)
  • N nozzles total = 5904
  • Velocity air nozzle ~ 75 m/s (Input flow rate = 1.1 l/s per stave)
  • D=0.35 mm, H=0.2 – 0.3 mm
  • Silicon detector: included (thermal conductivity)

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal cfd studies
St. Petersburg proposal-CFD studies
  • Preliminary CFD analysis: single nozzle, axisymmetric
  • Total area to cool down per stave = 46.2 cm2
  • Considering 152 nozzles, each one has to cool down 0.28 cm2
  • Assuming this area as the one of a circle, R = 3 mm
  • Studies for three cases:

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal cfd studies1
St. Petersburg proposal-CFD studies

q=0.5 W/cm^2

Velocity Magnitude [m/s]

vNozzle=50 m/s

vNozzle=75 m/s

H= 0.3 mm

H= 0.2 mm

H= 0.2 mm

H= 0.3 mm

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal cfd studies2
St. Petersburg proposal-CFD studies

T_Sensor [C] for q=0.3 W/cm^2

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal cfd studies3
St. Petersburg proposal-CFD studies

T_Sensor [C] for q=0.5 W/cm^2

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal cfd studies4
St. Petersburg proposal-CFD studies

Total pressure sensor [Pa]

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal cfd studies5
St. Petersburg proposal-CFD studies

q=0.5 W/cm^2

Total pressure sensor [Pa]

vNozzle=50 m/s

vNozzle=75 m/s

H= 0.3 mm

H= 0.2 mm

H= 0.2 mm

H= 0.3 mm

ALICE ITS - WG4 Meeting - 28th March 2012

slide14
St. Petersburg proposal analysis

ALICE ITS - WG4 Meeting - 28th March 2012

slide15
St. Petersburg proposal analysis

Mechanical analysis

Si Material Properties

(assumedasisotropic)

Si

E=155.8 GPa

ν=0.2152

G=64.1 Gpa

Strenght=200 MPa (depends on process and thickness)

Geometry

(a xb x thickness) 2.5mmx2.5mmx0,05mm

Appliedpressureloads

400Pa

500Pa

3000Pa

600Pa

b

4000Pa

700Pa

5400Pa

800Pa

a

Geometry

Boundaryconditions

4 glued area 0.25x0,25mm

Clamped ( 3 translationalthreerotationaldegreesoffreedomblocked),

(a xb x thickness) 5mmx5mmx0,05mm

Appliedpressureloads

3000Pa

4000Pa

5400Pa

ALICE ITS - WG4 Meeting - 28th March 2012

slide16
St. Petersburg proposal analysis

Appliedpressureloads

Max 800Pa, (2.5 x2.5 x 0.5)mm

Max displacement=0,05µm

Max stress=2.14 MPa

Max 5390Pa, (2.5 x2.5 x 0.5)mm

Max displacement=0,2µm

Max stress=7.37MPa

Max 5390Pa, (5 x5 x 0.5)mm

Max displacement=1,74µm

Max stress=14MPa

ALICE ITS - WG4 Meeting - 28th March 2012

st petersburg proposal optimization
St. Petersburg proposal optimization

Optimal geometrical settings for increasing Nu:

matches approximately the length of the jet’ s potential core, region where local heat transfer coefficients achieve higher values.

Example: for D = 0.35 mm, HOP~1.75 mm

Need to be checked!

ALICE ITS - WG4 Meeting - 28th March 2012

slide18
Air cooling update: CFD-Team Proposal

ALICE ITS - WG4 Meeting - 28th March 2012

slide19
Simulations update
  • Longitudinal heat conduction in the stave taken into account
  • More accurate turbulence modeling and mesh
  • Only layer1 & layer2 are cooled, heat from layer 3 is neglected
  • Inlet air temperature = 10 °C

ALICE ITS - WG4 Meeting - 28th March 2012

slide20
CFD model

IN

OUT

IN

LAYER3

IN

LAYER2

LAYER1

OUT

BEAM PIPE

IN

AXIS

  • INLET = BP/Layer1 + Layer2/Layer3 (velocity independently fixed at the 2 inlets)
  • OUTLET = Layer1/Layer2
  • 2D axisymmetric simulations, no buoyancy
  • NEW CFD MODEL: accounts for Si thickness (conduction)

ALICE ITS - WG4 Meeting - 28th March 2012

slide21
Velocity contours: vInlet=10 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

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Pressure contours: vInlet=10 m/s

Temperatures:

q=0.1 W/cm2, TAir-Outlet= 13 °C

q=0.3 W/cm2, TAir-Outlet=20 °C

q=0.5 W/cm2, TAir-Outlet= 27 °C

Tair-Inlet= 10 °C

ALICE ITS - WG4 Meeting - 28th March 2012

slide23
Stave temperature: vInlet=10 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

slide24
Stave temperature: vInlet=10 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

slide25
Stave temperature: vInlet=10 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

slide26
Velocity contours: vInlet=5 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

slide27
Pressure contours: vInlet= 5 m/s

Temperatures:

q=0.1 W/cm2, TAir-Outlet=17 °C

q=0.3 W/cm2, TAir-Outlet= 32 °C

q=0.5 W/cm2, TAir-Outlet= 47°C

TAir-Inlet= 10 °C

ALICE ITS - WG4 Meeting - 28th March 2012

slide28
Stave temperature: vInlet=5 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

slide29
Stave temperature: vInlet=5 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

slide30
Stave temperature: vInlet=5 m/s

ALICE ITS - WG4 Meeting - 28th March 2012

slide31
Next steps
  • Results shown for flat structure.
  • Next step would be performing studies for the triangular-shaped structure

ALICE ITS - WG4 Meeting - 28th March 2012

slide32
Conclusions: air cooling
  • St. Petersburg proposal:
    • Cooling performance of the first preliminary design is acceptable
    • The distribution of the air flow must be checked
    • Pressure on the stave may be an issue
  • CFD-Team air cooling proposal:
    • Compared with St. Petersburg proposal, cooling performance is lower.
    • Less material budget (in principle)
    • Lower mechanical stresses
    • Better cooling performance can be achieved using triangular structure (thermal fin)

ALICE ITS - WG4 Meeting - 28th March 2012

slide33
Cooling from the ends of the staves proposal

ALICE ITS - WG4 Meeting - 28th March 2012

cooling from ends proposal
Cooling from ends proposal

Optimal solution from the point of view of the material budget

Procedure: qMaxallowed for different material thicknesses (t) and thermal conductivities.

  • Boundary Conditions:
  • Desired maximum temperature gradient (ΔT)
  • Stave length/width
  • Thermal conductivity

ALICE ITS - WG4 Meeting - 28th March 2012

cooling from ends proposal1
Cooling from ends proposal

ALICE ITS - WG4 Meeting - 28th March 2012

cooling from ends proposal2
Cooling from ends proposal

ALICE ITS - WG4 Meeting - 28th March 2012

cooling from ends proposal3
Cooling from ends proposal

ALICE ITS - WG4 Meeting - 28th March 2012

cooling from ends proposal4
Cooling from ends proposal
  • Conclusions:
  • Low material Budget
  • Only feasible if:
    • Power density decreases by 10 times
    • High conductivity material is used (k > 1500 W/mK)

ALICE ITS - WG4 Meeting - 28th March 2012

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