its upgrade: cooling analysis progress

E. Da Riva/M. Gomez Marzoa 1ALICE ITS - WG4 Meeting - 28th March 2012

ITS Upgrade:Cooling analysis

progress

Enrico DA RIVA (EN-CV-PJ)

Manuel GOMEZ MARZOA (EN-CV-PJ)

28th March 2012


Contents

1. St. Petersburg mechanical layout proposal- Gas cooling scheme- Cooling solution-analysis- CFD studies- Mechanical analysis (Corrado Gargiulio)- Optimization

2. CFD-Team Air Cooling proposal3. Cooling from the ends proposal


St. Petersburg gas cooling scheme

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

CFD-Team: asked to analyze the performance of this solution


St. Petersburg gas cooling schemeAir flow into the shells and out through small holes to Si sensors.

Si sensor ~ 50 µm

Air INLETD=1.5 mm (variable)

H=0.2-0.3 mm (variable)

Array pitch = 5 mm Array of holes (OUTLET)D=0.35 mm


St. Petersburg proposal analysisDetector Thermal requirements: Detector working temperature = 30 °C Power density = 0.3 - 0.5 W/cm2

TAIR-INLET = +14 °C (minimum +7 °C – dew point)

HTC_Needed [W/(m^2 K)] q [W/cm^2] 0.3 0.4 0.5

T_Inlet [°C]7 130 170 22010 150 200 25014 190 250 310

MAIN TARGET


St. Petersburg proposal analysisBasic energy balance:

𝑄=�̇�𝑐𝑝 Δ𝑇

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

42 𝑙𝑠38 𝑠𝑡𝑎𝑣𝑒𝑠=𝟏 .𝟏𝟑 𝒍

𝒔


St. Petersburg proposal analysisCooling solution can be modeled as an array of impinging jets:

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

Popiel [2], Goldstein [3]

Not applicable (out of range)

CFD can predict the HTC for the proposed geometry

Considering: A single nozzle. Uniform distribution of air among nozzles. N nozzles per stave = 152 (1st layer), 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)


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:Air flow rate [l/s]

Nozzle air vel. [m/s]

0.42 280.75 501.13 75


St. Petersburg proposal-CFD studiesVelocity Magnitude [m/s]

vNozzle=75 m/s

q=0.5 W/cm^2vNozzle=50 m/s

H= 0.2 mm H= 0.2 mm H= 0.3 mmH= 0.3 mm


St. Petersburg proposal-CFD studiesT_Sensor [C] for q=0.3 W/cm^2


St. Petersburg proposal-CFD studiesT_Sensor [C] for q=0.5 W/cm^2


St. Petersburg proposal-CFD studiesTotal pressure sensor [Pa]


St. Petersburg proposal-CFD studiesTotal pressure sensor [Pa]

vNozzle=75 m/s

q=0.5 W/cm^2vNozzle=50 m/s

H= 0.2 mm H= 0.2 mm H= 0.3 mmH= 0.3 mm

ALICE ITS - WG4 Meeting - 28th March 2012 14

4,3

3. * For reference.

290*

Fitting

Step5*

2,5*

5*

15

T/2 0,05 BC

A0,01 A

1. The parts are assembly with glue ARALDIT STANDART.

2

3

ALC-1008

5

Cover 15mm11

Panel - V type

284*

300

451

152 holes ?0,4*

E

View E

1

ALC-10614

1

Panel - Q type

3 ALC-1060

1 Down panel 15mm L290 ALC-1059

21

QuantName.Drawin numberPos.Parts

ALC-1031

0.02 Epoxy glue Araldite RapideMaterials

TauroIgolkine

5:1

ALC-0116

Air cooling panel 15mm

ALICE

ORGANISATION EUROPEENNE POUR LA RECHERCHE NUCLEAIRE EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH GENEVE

CERN

ESHELLE SCALE

NOM

DESSINE

CONTROLE

VU

REMPLACE

St. Petersburg proposal analysis

E. Da Riva/M. Gomez Marzoa


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

500Pa600Pa700Pa800Pa

Applied pressure loads

Boundary conditions4 glued area 0.25x0,25mmClamped ( 3 translational three rotational degrees of freedom blocked),

Si Material Properties (assumed as isotropic)SiE=155.8 GPaν=0.2152G=64.1 GpaStrenght=200 MPa (depends on process and thickness)

400Pa

3000Pa4000Pa5400Pa

a

b3000Pa4000Pa5400Pa

(a xb x thickness) 5mmx5mmx0,05mmApplied pressure loads

Geometry

Geometry

St. Petersburg proposal analysisMechanical analysis



Max displacement=0,05µmMax stress=2.14 MPa

Applied pressure loads

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

Max displacement=0,2µmMax stress=7.37MPa

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

Max displacement=1,74µmMax stress=14MPa

Max 5390Pa, (5 x5 x 0.5)mm

St. Petersburg proposal analysis


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!


Air cooling update: CFD-Team Proposal


Radius [mm]

Diameter [m]

Stave Length [m]

Detector Heat Flux [W cm-2]

0.1 0.3 0.5

Heat Flow Rate [W]

Beam Pipe 19.8 0.0396

Cylinder1 22 0.044 0.268 37 111 185

Cylinder2 28 0.056 0.268 47 141 235

Cylinder3 36 0.072 0.268

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

IN

IN

OUT


CFD model

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)

LAYER1LAYER2

LAYER3

BEAM PIPE

AXIS

IN

INOUT


Velocity contours: vInlet=10 m/s


Pressure contours: vInlet=10 m/s

Temperatures:q=0.1 W/cm2, TAir-Outlet= 13 °Cq=0.3 W/cm2, TAir-Outlet= 20 °Cq=0.5 W/cm2, TAir-Outlet= 27 °C

Tair-Inlet= 10 °C


Stave temperature: vInlet=10 m/s


Velocity contours: vInlet=5 m/s


Pressure contours: vInlet= 5 m/s

Temperatures:q=0.1 W/cm2, TAir-Outlet=17 °Cq=0.3 W/cm2, TAir-Outlet= 32 °Cq=0.5 W/cm2, TAir-Outlet= 47 °C

TAir-Inlet= 10 °C


Next steps

Results shown for flat structure. Next step would be performing

studies for the triangular-shaped structure


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)


Cooling from the ends of the staves

proposal

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

Cooling from ends proposal


Optimal solution from the point of view of the material budget

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

𝑞𝑀𝑎𝑥=8𝑘𝑡 Δ𝑇

𝐿2[𝑊𝑐𝑚2 ]



Fixed Parameters L_Stave [m] 0.3Si k [W m^-1 K^-1] 150w_Stave [m] 1.50E-02

k [W m^-1 K^-1] 1000

ΔT [C]Thickness [µm] q_Max_Allowed [W cm^-2] Comments5 50 3.33E-03Only silicon

100 4.44E-03 150 6.67E-03 200 8.89E-03 500 2.22E-02

10 50 6.67E-04Only silicon 100 8.89E-03 150 1.33E-02 200 1.78E-02 500 4.44E-02




k [W m^-1 K^-1] 1500


100 6.67E-03 150 1.00E-02 200 1.33E-02 500 3.33E-02





k [W m^-1 K^-1] 2000


100 8.89E-03 150 1.33E-02 200 1.78E-02 500 4.44E-02




Conclusions: Low material Budget Only feasible if:

Power density decreases by 10 times High conductivity material is used (k > 1500 W/mK)

its upgrade: cooling analysis progress

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