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26 May 2010 Hans Postema - CERN
Status and plan for the development and construction
of CO2 Cooling System for Pixel Upgrade
1
Why CO2?
• Radiation hard• Not electrically conductive, non corrosive• Not flammable, not toxic• Has excellent thermodynamic properties for micro-
channels. • Low dT/dP• Low mass • Low liquid/vapour density ratio• Low viscosity• High latent heat• High heat transfer coefficient• Environmental friendly
Hans Postema - CERN26 May 2010 2
Pressure advantage
• Intuitively, higher pressures seem a disadvantage but:
• Gas flow at higher pressures needs smaller pipe diameters
• Pressure drops due to flow become less significant, allowing smaller pipes
• Small pipes can easily support the required pressures
Hans Postema - CERN26 May 2010 3
Selection
• Many activities in different places
• Good overview requires several hours
• Global overviews risk to be repeating themselves through the year
• This presentation is a selection of some important achievements over the last few months
Hans Postema - CERN26 May 2010 4
FPIX tube (February)
Hans Postema - CERN26 May 2010 5
FPIX in fridge
Hans Postema - CERN26 May 2010 6
Layout of the test section
Length of the tube: 1mInner diameter: 1.4mmWall thickness: 100µm
13 temperature sensors glued on the tubeCopper blocks for power supply
Improved insulation
• Environment influences obviously the readings of the sensors
• Better insulation of the tube needed
• Freezer must be at the same temperature as the cooling fluid
Kapton tapeTube Armaflex
Improvements
Better results through insulating the tube and keeping the temperatureinside the freezer at the temperature of the liquid
Temperature drop vs. tube length at 0°C
Sensor 1 and 13 are before or after the heated test section
Temperature drop vs. tube length at -15°C
Sensor 1 and 13 are before or after the heated test section
Comparison to correlations
Temp. Thome Friedel Test 1 Test 2
Temperature drop9°C
0.34 °C 0.27 °C 0.05 °C 0.18 °C
Pressure drop 0.35 bar 0.32 bar 0.34 bar 0.36 bar
Temperature drop0°C
0.37 °C 0.37 °C 0.49 °C 0.52 °C
Pressure drop 0.43 bar 0.38 bar 0.50 bar 0.59 bar
Temperature drop-15°C
0.39 °C 0.49 °C 0.82 °C 0.89 °C
Pressure drop 0.61 bar 0.68 bar 1.25 bar 1.37 bar
Temperature drop-30°C
0.47 °C 0.67 °C 1.41 °C 1.46 °C
Pressure drop 1.05 bar 1.33 bar 3.63 bar 3.93 bar
Comparison @ Tsat=9°
Comparison @ Tsat=0°
Comparison @ Tsat=-15°
Comparison @ Tsat=-30°
Conclusions of tests
• Software of some correlations now fully debugged an operational
• Interesting differences between calculations and measurements remain
• FPIX tube can reliably cool the requested heat load of 124 W
• dT over tube length < 3 degrees C
• dT due to HTC < 3 degrees C
Hans Postema - CERN26 May 2010 17
18 May 2010
• Reached an important milestone
• First time that the Full Scale cooling plant test setup was running
• No problem in priming the pump
• Pump runs very quiet and smooth, no vibrations
• The result of a year of work by a dozen people
Hans Postema - CERN26 May 2010 18
Cooling plant
Hans Postema - CERN26 May 2010 19
Including dummy load
Hans Postema - CERN26 May 2010 20
Chiller part
Hans Postema - CERN26 May 2010 21
View with control rack
Hans Postema - CERN26 May 2010 22
Hans Postema - CERN26 May 2010 23
Control interface
Hans Postema - CERN26 May 2010 24
Next steps
• Commissioning of the plant at ambient temperature
• Test run of Atlas IBL cooling loop
• Installation of accumulator, required for low temperature operation
• Commissioning of the plant at low temperature
Hans Postema - CERN26 May 2010 25
Strategy (1)
• CO2 cooling plants cannot be bought off the shelf
• Relevant experience is not available in industry
• Current activities are generating the necessary experience “in house”
• Future CO2 cooling plants shall be designed and constructed “in house”
Hans Postema - CERN26 May 2010 26
Strategy (2)
• Cooling plant shall be constructed early, leaving 1 year for commissioning on the surface and 1 year for installation in UX
• To avoid schedule constraints, one cooling plant foreseen for detector commissioning in TIF, and one for installation in the CMS cavern
Hans Postema - CERN26 May 2010 27
Qualification
• Engineering and design shall follow the principles applied in aero-space or safety critical industrial applications
• Excellent workmanship shall have a priority over low-cost
• Extended “burn in” period necessary, comparable with satellites (1 year)
Hans Postema - CERN26 May 2010 28
Safety
• High pressure is a safety concern when combined with larger volumes (stored energy)
• Pipe-work and components are in PED class 1 (Pressure Equipment Directive) DN<32 requiring “Good Practice”
• Storage tanks or Accumulators are in class 4 requiring certification
• Accumulator for the full scale test setup will be produced with a CE certificate, by NIKHEF
Hans Postema - CERN26 May 2010 29
Schedule
• 2010 – Testing of Full Scale setup
• 2011-2012 – Engineering and design of detector parts, pipe-work, fittings and final plant
• 2013 – Construction of cooling plants
• 2014 – Burn in of cooling plants in TIF
• 2015 – Installation cooling plant in UX
• 2016 – Installation of detector
Hans Postema - CERN26 May 2010 30
Participating groups
• CERN – Atlas• CERN – CMS• CERN – PH-DT• CERN – EN-CV• CERN – Cryolab• EPFL Lausanne• Fermilab• IPN Lyon
• NIKHEF Atlas LHCb• PSI• RWTH Aachen• SLAC Atlas• University Esslingen• University Karlsruhe
Hans Postema - CERN26 May 2010 31
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