1. 24 June 2010 Immanuel Gfall (HEPHY Vienna) CO 2 Cooling for PXD/SVD IDM Meeting

2. CO2 Cooling for PXD/SVD Talk Outline CO 2 History How to use CO 2 for cooling Cooling system layouts Requirements for SVD II CO 2 merits Costs Maintenance Timeline 24 June 2010Immanuel Gfall (HEPHY Vienna)2

3. CO2 Cooling for PXD/SVD CO 2 History 1866: first reported CO 2 cooling system was built (dry out) Until 1930: Wide spread development and use of CO 2 systems 1930: CFC/ HCFC era starts and pushes CO 2 to extinction 1988: first patent draft for transcritical CO 2 system 1992: first experimental data on mobile AC system published 2000: TU Dresden introduces a CO 2 powered heat pump 2001: Commercial introduction of R744 hot water heat pumps in Japan 2009: Fully operational CO 2 cooling system at CERN (Velo Detector/ LHCb) CO 2 is the refrigerant of choice for future detector upgrades (CMS Pixel, ATLAS Pixel, …) 24 June 2010Immanuel Gfall (HEPHY Vienna)3

4. CO2 Cooling for PXD/SVD Mollier Chart (log p-H) Gas Temperature Gas Density Entropy Saturation Line 24 June 2010Immanuel Gfall (HEPHY Vienna)4

5. CO2 Cooling for PXD/SVD Working Principle Cooling effect of boiling fluid is used! Boiling and evaporation is established through enthalpy change of the working fluid and pressure reduction This enthalpy change is supplied by a heat source (read out chips) The dissipated power of a heat source and the change of enthalpy are correlated: For ideal processes the power dissipated by the source = power absorbed by the fluid This process is different from single phase cooling cycles 24 June 2010Immanuel Gfall (HEPHY Vienna)5

6. CO2 Cooling for PXD/SVD CO 2 Basic Cooling Cycle CO 2 can be operated as a transcritical or subcritical cycle Heat is emitted in a condenser to reduce the fluids enthalpy Pressure reduction leads to temperature change of fluid Fluid is evaporated under constant pressure This stage is used to absorb heat Compressor is used to increase pressure to restart the cycle Cooling Heat Exchange Compression Pressure Reduction c a b d 24 June 2010Immanuel Gfall (HEPHY Vienna)6

7. CO2 Cooling for PXD/SVD Issues with Compressor Cycle Compressor needs gas on suction side Heater is required to ensure fully evaporated fluid Warm supply line for liquid cooling fluid is possible Additional heater is required for warm return line Oil free compressor is needed! Compressor Condenser Heater Heat Exchanger Pressure Reduction Heat Load Temperature Regulation 24 June 2010Immanuel Gfall (HEPHY Vienna)7

8. CO2 Cooling for PXD/SVD 2-Phase Accumulator Controlled Loop Accumulator regulates pressure Accumulator ensures liquid CO 2 at suction side of the pump Membrane pump used instead of compressor A pump pressurizes the fluid and propels it Internal heat exchanger warms up sub cooled fluid before pressure reduction Fluid never changes to purely gaseous state 24 June 2010Immanuel Gfall (HEPHY Vienna)8

9. CO2 Cooling for PXD/SVD 2PACL LHCb Design Chiller is used to cool CO 2 Accumulator is the process controlling element Concentric heat exchanger tube used to warm up liquid CO 2 up to the saturation point Picture demonstrates LHCb Velo layout 24 June 2010Immanuel Gfall (HEPHY Vienna)9

10. CO2 Cooling for PXD/SVD Cooling Unit Components CO 2 closed cycle test plant from Hans Postema Lewa Pump Reinforced Heat Changer 24 June 2010Immanuel Gfall (HEPHY Vienna)10

11. CO2 Cooling for PXD/SVD Compressor vs. Accumulator Traditional cooling process passes through the dry-out zone Potential damage of electronics 2PACL design avoids dry out zone intrinsically 24 June 2010Immanuel Gfall (HEPHY Vienna)11

12. CO2 Cooling for PXD/SVD Cooling Requirements Smallest possible material budget in the acceptance region Operating temperature @ -20°C for SNR improvement Radiation hard coolant Cooling system needs to handle 1kW+ of dissipated heat (including PXD) Cooling fluid should be dielectric, non-flammable, non-toxic and non-corrosive Immanuel Gfall (HEPHY Vienna)24 June 2010Immanuel Gfall (HEPHY Vienna)05.04.201012

13. CO2 Cooling for PXD/SVD Cooling Boundary Conditions Immanuel Gfall (HEPHY Vienna)24 June 2010 Power dissipation/APV: 0.4 W 1 Origami sensor features 10 APVs Total Origami power dissipation: 356 W 404 W dissipated at the hybridboards Total SVD power dissipation: 760 W Origamis/ Ladder LaddersAPVs Origami APVs Hybrid Layer 6317510340 Layer 5214280 Layer 4110100200 Layer 3080192 Immanuel Gfall (HEPHY Vienna)05.04.201013

14. CO2 Cooling for PXD/SVD CO 2 Merits CO 2 fulfills the requirements Low material budget inside acceptance region (CO 2 has a long radiation length) Thinner tubes required compared to other cooling fluids Small temperature gradient over long lines Fast temperature regulation capacity Supreme heat capacity and transport Cooling process requires low mass flow Radiation hard CO 2 is cheap an easily available 24 June 2010Immanuel Gfall (HEPHY Vienna) d=3.6mm T = 0.07mm d=0.9mm T = 0.12mm CuNi Tubes! 14

15. CO2 Cooling for PXD/SVD Costs Cooling plant Piping and additional components Test unit and test setups Construction costs Total: ~17 million Yen (~160k €) 24 June 2010Immanuel Gfall (HEPHY Vienna)15

16. CO2 Cooling for PXD/SVD Maintenance Maintenance schedule: every year Relatively passive system = little work to do Pump is the only service part Check connectors and valves for leaks CO 2 level check is automated CO 2 can easily be re-filled on demand 24 June 2010Immanuel Gfall (HEPHY Vienna)16

17. CO2 Cooling for PXD/SVD Outlook New team member in Vienna to tackle CO 2 blow system setup CO 2 blow system development until December 2010 SVD/PXD mockup until December 2010 Early 2011: Cooling tests with mockup 2011: Design and development of CO 2 cooling plant control system 2012: Construction and test of CO 2 cooling plant 24 June 2010Immanuel Gfall (HEPHY Vienna)17