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ITS Upgrade: Cooling analysis progress

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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ITS Upgrade: Cooling analysis progress

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  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. St. Petersburg proposal-CFD studies T_Sensor [C] for q=0.3 W/cm^2 ALICE ITS - WG4 Meeting - 28th March 2012

  11. St. Petersburg proposal-CFD studies T_Sensor [C] for q=0.5 W/cm^2 ALICE ITS - WG4 Meeting - 28th March 2012

  12. St. Petersburg proposal-CFD studies Total pressure sensor [Pa] ALICE ITS - WG4 Meeting - 28th March 2012

  13. 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

  14. St. Petersburg proposal analysis ALICE ITS - WG4 Meeting - 28th March 2012

  15. 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

  16. 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

  17. 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

  18. Air cooling update: CFD-Team Proposal ALICE ITS - WG4 Meeting - 28th March 2012

  19. 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

  20. 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

  21. Velocity contours: vInlet=10 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  22. 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

  23. Stave temperature: vInlet=10 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  24. Stave temperature: vInlet=10 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  25. Stave temperature: vInlet=10 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  26. Velocity contours: vInlet=5 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  27. 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

  28. Stave temperature: vInlet=5 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  29. Stave temperature: vInlet=5 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  30. Stave temperature: vInlet=5 m/s ALICE ITS - WG4 Meeting - 28th March 2012

  31. 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

  32. 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

  33. Cooling from the ends of the staves proposal ALICE ITS - WG4 Meeting - 28th March 2012

  34. 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

  35. Cooling from ends proposal ALICE ITS - WG4 Meeting - 28th March 2012

  36. Cooling from ends proposal ALICE ITS - WG4 Meeting - 28th March 2012

  37. Cooling from ends proposal ALICE ITS - WG4 Meeting - 28th March 2012

  38. 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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