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CO 2 cooling measurements at NIKHEF EPFL/LTCM meeting at Cryolab

CO 2 cooling measurements at NIKHEF EPFL/LTCM meeting at Cryolab. Bart Verlaat CERN 30 September 2009. Evaporative cooling systems used at CERN experiments. Traditional method: (Atlas). Vapor compression system (C3F8). Liquid. Vapor. Compressor. Heater. Warm transfer.

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CO 2 cooling measurements at NIKHEF EPFL/LTCM meeting at Cryolab

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  1. CO2cooling measurements at NIKHEFEPFL/LTCM meeting at Cryolab Bart Verlaat CERN 30September 2009

  2. Evaporative cooling systems used at CERN experiments Traditional method: (Atlas) Vapor compression system (C3F8) Liquid Vapor Compressor Heater Warm transfer BP. Regulator Pressure 2-phase Cooling plant Detector Enthalpy 2PACL method: (LHCb) Pumped liquid system (CO2) Liquid Vapor Compressor Pump Pressure Chiller Liquid circulation Cold transfer 2-phase Enthalpy Cooling plant Detector

  3. 2-Phase Accumulator Controlled Loop (2PACL) 2PACL for AMS en LHCB \ • 2PACL was developed for the AMS-TTCS • 2PACL also implemented in LHCb-VELO In 2-phase area T=Constant 3 2 P 1 5 4 5 Liquid Vapor Pump Pressure Radiator 2-phase 2 4 3 1 LHCb-Velo Deep space = Cold • Q= 150 watt • T= +15ºC to -20ºC AMS-Tracker Enthalpy

  4. 2-Phase Accumulator Controlled Loop (2PACL) 2PACL for AMS en LHCB \ • 2PACL was developed for the AMS-TTCS • 2PACL also implemented in LHCb-VELO In 2-phase area T=Constant 3 2 P 1 5 4 5 Liquid Vapor Pump Pressure 2-phase 2 4 3 1 Chiller = Also cold LHCb-Velo • Q= 1500 Watt • T= +8ºC to -30ºC Enthalpy

  5. LHCb-VTCS The cooling tube temperature is: • Easy to control • Very stable • Independent of primary cooler temperature Accumulator temperature = Cooling tube temperature Temperature of the chiller 0 -10 -20 -30 Temperature of space radiator Temperature (ºC) Time 1 orbit (~1.5h) AMS-TTCS

  6. CO2 2PACL Lab Cooler 2PACL with PLC Test box with experiment • Supplies: • Massflow • Enthalpy • Pressure • Supplies: • Cold Cryostat • Supplies: • Power • Supplies: • Temperature • Pressure • Voltage • Demand for: • Mass flow • Enthalpy • Pressure Power supply • Demand for: • Temperature • Demand for: • Power • Supplies data: • HTC • Pressure drop • CHF • Dry out PC with PVSS to control the cooler and experiment

  7. Nikhef CO2 cooling test facility2PACL lab cooler and test box Siemens PLC Room temperature bottle as accumulator Room temperature evaporation in test tube Cold water condenser (8ºC) 2PACL CO2 circulator is operational for room temperature CO2 cooling. Will be upgrade to a cold cooler the coming months 2PACL lab cooler prototype at NIKHEF

  8. Current 2PACL configuration: Warm Cooler F CO2 return E H2O in C bypass D CO2 out H2O out B C CO2 bottle FT101 A B A D E • Upgrade to cold cooler: • Replace bottle with LHCb accumulator • Connects condenser to Cryostat

  9. CO2 heat transfer and pressure drop measurements • In HEP we are using CO2 in un unexplored area. • Mini channels (<2mm) • Low temperature (<-20ºC) • No commercial applications = limited research • Current prediction models are therefore not verified • Heat Transfer Coefficient (HTC) • Dry-out • Pressure drop • Critical Heat Flux (CHF) • Those properties depend on a lot of variables • Mass flux • Heat flux • Pressure (=Temperature) • Enthalpy (=Vapor quality) • Tube geometry • Automatic scanning of the properties with PVSS controlling the set-points of the 2PACL research plant. Heat load Dry-out response to increasing heat PVSS interface

  10. Temperature (ºC) Pressure (Bar) Tube inner diameter (mm) DCO2≈1.4 mm DC3F8≈3.6 mm IBL stave cooling tube sizing (1) • Traditional method: • Calculating dP & dT according to the Friedel correlation • - Set threshold for max. temperature gradient. Assumed threshold: 1ºC • IBL stave assumptions: • 800 mm long • 150 Watt power (Non redundant) • -25ºC cooling fluid temperature • 40% exit vapor quality dP according to Friedel

  11. IBL stave cooling tube sizing (2) • IBL stave assumptions: • 800 mm long • 150 Watt power (Non redundant) • -25ºC cooling fluid temperature • 40% exit vapor quality DCO2 = 1.4 mm DC3F8 = 3.6 mm Heat Transfer coefficient (W/m2K) Temperature distribution (ºC) CO2 C3F8 CO2 Tube wall Heat transfer according to Kandlikar dT= ~3ºC C3F8 Fluid Tube length (m) Tube length (m)

  12. Kandlikar IBL stave cooling tube sizing (3) Nowadays more fancy design tools are available: And guess, they do not comply at all! (Welcome in the magic world of 2-phase flow!) Corresponding zone Results of the 1.4 mm CO2 tube in the Thome flow pattern maps Thome predicts an early dry-out

  13. Are these spikes from a LHCb VELO test the dry-out which Thome predicts?

  14. Prototype Atlas IBL cooling tube. Q≈100 Watt Inlet Capillary 0.6mmID x 4m Outlet Capillary 2mmID x 4m IBL stave: 1.6mmID x 800mm • Hand bended 2.5x0.25 mm soft stainless tube • Capillaries should be flexible “so they can be handled as a cable” IBL cooling tube in the Nikhef test box

  15. IBL Tube cooling tests(Warm Cooler) Temperature versus Power flow 1.6 g/s Exceeding Critical Heat Flux Dry-out Saturation temperature Sub-cooled Tests by Auke-Pieter Colijn IR pictures: flow=1.5g/s; p=61bar; T saturation=24.5°C Dry-out movie @ youtube (145 W -> 200W -> 145 W -> 0W)

  16. IBL tube heat transfer resultsMF=1.6 g/s, T=24.6ºC Thome heat transfer 58 Watt (17222 W/m2) 95 Watt (28208 W/m2) Kandlikar heat transfer Tube in flow pattern diagram Measured heat transfer 140 Watt (41570 W/m2) 176 Watt (52349 W/m2)

  17. Conclusions • 2PACL is easy to operate and very stable => ideal system for accurate measurements • 2PACL lab cooler under construction at Nikhef • Runs at room temperature evaporation • Will be upgrade to run cold the coming months • 2PACL lab cooler will be used for Atlas upgrade testing • Intention to use 2PACL for generic research to validate existing models (Collaboration with EPFL?)

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