THERMAL MANAGEMENT (COOLING) OF THE CBM SILICON TRACKING SYSTEM Kshitij Agarwal Eberhard Karls Universitt Tbingen, Tbingen, Germany for the CBM Collaboration OUTLINE 1. 2. 3. 4. 5. 6. Introduction of the CBM Silicon Tracking System Motivation & challenges for thermal management of CBM-STS Optimisation of thermal interfaces Optimisation of cooling plates
Feedthrough test setup Conclusion and outlook DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 1 CBM SILICON TRACKING SYSTEM CBM aims to explore regions of high-baryonic densities of QCD phase diagram Requires detection of rare probes 105 107 collisions/sec (Au-Au) STS Group Report HK 61.1, 14:00, E. Lavrik Momentum Resolution High track reconstruction efficiency with pile-up free track point determination
Silicon Tracking Station Key to CBM Physics 8 Tracking Stations :- 896 double-sided micro-strip sensors Low Material Budget :- 0.3% - 1% X0 per station Radiation tolerance: 1014 neq cm-2 (1 MeV equivalent) ~ 1.8 million read-out channels ~ 16000 r/o ASICs STS-XYTER DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 40kW Power Dissipation!!! 2 MOTIVATION & CHALLENGES FOR STS COOLING Adverse effects of high-radiation Leakage current increases with fluence & temperature
Reduces signal-to-noise ratio (STS req.: S/N > 10) Thermal Runaway Reverse annealing of depletion voltage STS Sensor Radiation Damage HK 61.5, 15:15, E. Friske Sensor cooling could control these adverse effects STS sensor temp. -10C to -5C at all times DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 3 MOTIVATION & CHALLENGES FOR STS COOLING FEE (40kW)
Thermal Insulation Box Cooling Plate <-5C @sensors No cooling pipes inside detector acceptance Cooling of sensors (~ 1mW/cm2) forced convection (N2 cooling) + thermal enclosure Cooling of front-end electronics (~ 40kW) bi-phase CO2 cooling DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 4 OPTIMISATION OF THERMAL INTERFACES
Thermal Interface Materials (TIMs) increases area of contact at microscopic scale increase overall thermal conductivity (kair = 0.026 W/(mK) )K) ) Interface 1: (Fixed) Aluminium Nitride ASIC (Resistors) Interface 2: (Removable) Aluminium Nitride Aluminium Fin Interface 3: (Removable) FEE box Cooling Plate 5 OPTIMISATION OF THERMAL INTERFACES Power Dissipated: 160W Exp. IR Camera + PT100
FEA Solidworks Thermal Sim. H2O inlet: 15C @ 40lt/hr HTC: 750 W/mK Air Convection: 10 W/mK Radiation included DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 6 OPTIMISATION OF THERMAL INTERFACES Power Dissipated: 160W Key take-aways : H2O inlet: 15C @ 40lt/hr
HTC: 750 W/mK Air Convection: 10 W/mK Radiation included DPG Bochum 2018 A more viscous TIM (grease) has a better thermal performance than a relatively rigid TIM (graphite foil, thermal pad) Flattening the interfaces (~ 10m) improves the results substantially Good agreement ( 10%) between experiments & simulations K. Agarwal - Thermal Management of the CBM Silicon Tracking System 7 OPTIMISATION OF COOLING PLATE Bi-Phase CO2 cooling for STS-FEE (~ 40kW) CO2 heat transfer co-efficient depends on:
cooling plate's tube (diameter & length) () mass flow of the coolant () targeted amount of heat removal () STS cooling plate's boundary conditions for this study: Coolant temp. TCO2 = -40C Targeted heat removal = 1300W (~ 8 FEBs) Outlet Pressure - FIXED Inlet Temperature - FIXED DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 8 OPTIMISATION OF COOLING PLATE
Vapor Quality: (= 0: saturated liq.) (= 1: saturated vap.) Dry-out zone: Tubes inner surface is no longer in s inner surface is no longer in contact with liquid coolant Much lower Heat Transfer Co-eff Higher tube wall temperature Higher T (Local temp. diff. between T (Local temp. diff. between fluid and tube wall in tube) Outlet vapor quality SHOULD NOT reach dry-out! Solution: Higher mass flows DPG Bochum 2018
K. Agarwal - Thermal Management of the CBM Silicon Tracking System 9 OPTIMISATION OF COOLING PLATE Bi-Phase CO2 Pressure/Temp. Distribution v/s Tube Length Maximisation of: Mass defined at 50% from dry-out quality DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 10 OPTIMISATION OF COOLING PLATE
Operational Parameters look-up table (Diameters w.r.t. Swagelok VCR connections) Calculations based on: L. Cheng et al., Int. J. Heat Mass Transfer 51 (2006), p.111 & p.125 B. Verlaat et al., Proceedings of 10th IIR Gustav Lorentzen Conference on Natural Refrigerants (2012), GL-209 Z. Zhang, CERN-THESIS-2015-320 (2015) DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 13 11 FEEDTHROUGH INTEGRATION & TESTS 2300
All services (HV, LV, data transmission, cooling etc) will be routed through STS front panel Total available area = 1.5m 1425 Easy cabling & de-cabling Maintainence of thermal environment inside STS High-density thermally-insulating feedthroughs! + Micro Vertex Detector (MVD) + Beam Pipe Total: 1.5m (only) 12 FEEDTHROUGH INTEGRATION & TESTS
25C 50% RH -10C 1% RH 1st Dummy 108 cables squeezed in 2cm gap! Sealed with silicone & filled with PUR foam DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 13 FEEDTHROUGH INTEGRATION & TESTS Next Steps: Panel with 9 x EPIC H-DD 42 connectors will be fabricated (area: 20cm x 20cm, #pins: 378)
Shielded flat-band cables Thermal Insulation 25C 50% RH DPG Bochum 2018 -10C 1% RH Similar panels with different connectors & configurations will be thermally tested at Universitt Tbingen & electrically tested at GSI-Darmstadt Could be tested at mSTS K. Agarwal - Thermal Management of the CBM Silicon Tracking System
14 SUMMARY AND OUTLOOK Challenges of STS Thermal Management: STS sensors temp. < -5C Removal of FEE power (40kW) by bi-phase CO2 cooling Operation in thermal enclosure High-density thermally insulating feedthroughs for services Progress towards construction of cooling demonstrator: Thermal interfaces are optimised: Viscous TIM (grease etc.) more efficient Optimised operational parameters for cooling plates available Feedthrough dummys are under construction DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 15
SUMMARY AND OUTLOOK Sensor cooling: Heat-producing sensor dummies & N2 cooling system FEE cooling: Thermal FEA Simulations with different cooling plate designs + electronics Feasibility of cooling plates industrial manufacturing Cooling plant commissioning (TRACI XL) Environment management: Thermal enclosure & feedthroughs Integration: Aim towards start of production of parts by Sept 2018 DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 16 SUMMARY AND OUTLOOK Challenges of STS Thermal Management: STS sensors temp. < -5C Removal of FEE power (40kW) by bi-phase CO2 cooling
Operation in thermal enclosure High-density thermally insulating feedthroughs for services Progress towards construction of cooling demonstrator: Thermal interfaces are optimised: Viscous TIM (grease etc.) more efficient Optimised operational parameters for cooling plates available Feedthrough dummys are under construction Sensor cooling: Heat-producing sensor dummies & N2 cooling system THANKS A LOT FOR YOUR ATTENTION! FEE cooling: Thermal FEA Simulations with different cooling plate designs + electronics Feasibility of cooling plates industrial manufacturing Cooling plant commissioning Environment management: Thermal enclosure & feedthroughs Integration: Aim towards start of production of parts by Sept 2018 DPG Bochum 2018
K. Agarwal - Thermal Management of the CBM Silicon Tracking System 17 BACKUP SLIDES DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 20 MOTIVATION & CHALLENGES FOR STS COOLING Adverse effects of high-radiation Leakage current increases with fluence & temperature
Reduces signal-to-noise ratio (STS req.: S/N > 10) DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 3 MOTIVATION & CHALLENGES FOR STS COOLING Adverse effects of high-radiation Leakage current increases with fluence & temperature Reduces signal-to-noise ratio (STS req.: S/N > 10) Thermal Runaway MOTIVATION & CHALLENGES FOR STS
COOLING Adverse effects of high-radiation Leakage current increases with fluence & temperature Reduces signal-to-noise ratio (STS req.: S/N > 10) Thermal Runaway Reverse annealing of depletion voltage F. Hartmann, Evolution of Silicon Sensor Technology in Particle Physics, Springer Tracts in Modern Physics 275, DOI 10.1007/978-3-319-64436-3_2 DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 5 MOTIVATION & CHALLENGES FOR STS COOLING
Adverse effects of high-radiation Leakage current increases with fluence & temperature Reduces signal-to-noise ratio (STS req.: S/N > 10) Thermal Runaway Reverse annealing of depletion voltage Sensor cooling could control these adverse effects DPG Bochum 2018 STS sensor temp. -10C to -5C at all times K. Agarwal - Thermal Management of the CBM Silicon Tracking System 6 OPTIMISATION OF COOLING PLATE Bi-Phase CO2 Flow Pattern Map
50% from dry-out quality 25% from dry-out quality At dry-out quality Calculations based on: L. Cheng et al., Int. J. Heat Mass Transfer 51 (2006), p.111 & p.125 B. Verlaat et al., Proceedings of 10th IIR Gustav Lorentzen Conference on Natural Refrigerants (2012), GL-209 Z. Zhang, CERN-THESIS-2015-320 (2015) DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 12 OPTIMISATION OF COOLING PLATE Bi-Phase CO2 Pressure/Temp. Distribution v/s Tube Length
Mass defined at 50% from dry-out quality Calculations based on: L. Cheng et al., Int. J. Heat Mass Transfer 51 (2006), p.111 & p.125 B. Verlaat et al., Proceedings of 10th IIR Gustav Lorentzen Conference on Natural Refrigerants (2012), GL-209 Z. Zhang, CERN-THESIS-2015-320 (2015) DPG Bochum 2018 K. Agarwal - Thermal Management of the CBM Silicon Tracking System 13
