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VELO Thermal Control System

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  1. VELO Thermal Control System VELO Meeting 7 & 8 September 2005 @ CERN Bart Verlaat, Luc van Diepen, Berend Munneke & Martin Doets (NIKHEF), Frans Mul (VU)

  2. Detectors and electronics 23 parallel cooling connections Pressure Drop Capillaries VELO Thermal Control System Evaporator Section

  3. spacers Connection to sec. vacuum 27 capillaries Cooling Out VTCS Right Evaporator Cooling Inlet Bellow (tertiary vacuum) Cable & capillary channel Tube 1,5x0,25 Manifold Aluminum evaporator 5-part

  4. Cooling block Manufacturing 27 Cooling blocks have been produced! Vacuum oven Series mould

  5. Evaporator Manufacturing Capillary bundles Capillaries Outlet Manifold Inlet Manifold

  6. Chiller Control VTCS Test setup @ NIKHEF CO2 Control Pump=20Hz

  7. VELO Module Testing

  8. VELO Module Test results

  9. TEMPORARY COOLING SYSTEM / HEAT TRANSFER Pressure Relieve Valve on COOLING of a single cooling block heaters off Switch valve cooling block closed open gas liquid capillaries Heat exchanger manifold Switch valve

  10. TEMPORARY COOLING SYSTEM / HEAT TRANSFER Pressure Relieve Valve off Heating of a single cooling block heaters Heat exchanger on Switch valve cooling block open closed gas liquid capillaries 50ºC gas manifold Switch valve

  11. Cooling block installation jig (1) frame clamp handle clamp

  12. Cooling block installation jig (2)

  13. VTCS Tube routing in experimental area Cooling plant 2 concentric assemblies for 2 separate systems (left &right) Z=3.5m Z=2.9m Z=1.8.5m Z=0.5m Z=0m VELO Experiment Tube length Ca. 53m

  14. Concentric tube test results: • No unstable flow was detected. • Vertical up flow is added as static pressure to total pressure drop. • Total pressure drop is acceptable (ca. 1 bar ≈ 1.5ºC ΔT) • Concentric tube together with accumulator show a good and stabile evaporator pressure/temperature control. 81%=1620 W

  15. 2 3 5 6 1 7 4 Evaporator temperature at VELO = Accumulator temperature if pressure drop of return flow is small: TEvaporator = T5 = f(P5) [2-phase] P5 = P1 + dP5-1 P1 = P7 = f(T7) [2-phase] VTCSprinciples: Evaporator is always 2-phase due to heat exchange of concentric tube even if pump temperature is colder than accumulator temperature: Tpump = T1 = TR404a T1<T7, P1=P7 => [sub cooled] T3 ≈T5 [Heat exchange] T4=T3, P4<P3 [expansion, liquid to 2-phase] Accumulator 2-phase 2-phase gas Condenser Evaporator R404a chiller Restriction Pump Concentric tube liquid 2-phase liquid liquid 2-phase

  16. VTCS principles (Con’d) • Due to the combination of the accumulator and the concentric transfer tube the control of VTCS is limited to temperature control of the accumulator only. As long as the following parameters are set to be fixed: • Liquid temperature lower than to lowest required accumulator temperature. <-30ºC • Fixed massflow of CO2 such that the energy needed for pre heating the subcooled liquid is less than absorbed heat by the detector and environement. • Summarized settings: • Taccu = -25ºC Controlled • Tchiller -40ºC fixed • Massflow = 12.5 g/s fixed

  17. Typical two-phase loop cycle (CO2 as tertiary coolant) • A-B: Liquid pump • B-C: Pre-heating due to heat exchanger with EF • C-D: Expansion • D-E: Evaporation of CO2, heat is absorbed from heat source • E-F: Condensing in heat exchanger with B-C • F-A: Condensing to chiller Liquid B C P [bar] D E A F Liquid and Vapor Enthalpy [J/g]

  18. Transfer tube engineering drawing General overview

  19. Transfer tube engineering drawing Details at VELO

  20. Transfer tube engineering drawing Details at tunnel TX84

  21. Transfer tube engineering drawing Details at RB84

  22. Transfer tube engineering drawing Construction details

  23. Concentric transfer lines • Function of the concentric transfer lines: • Keep inlet liquid CO2 sub-cooled with cooling overcapacity of return line. => Avoid vapor generation in feed line! • The outlet tube boiling temperature is ALWAYS lower than the inlet tube boiling temperature. A good thermal coupling like in a concentric option per definition keeps the inlet tube temperature lower than its local boiling temperature. • Baseline concept: • Ø6x1mm inner tube (Inlet feed) into Ø16x1mm outer tube (outlet return). • Inner and outer tubes are orbital welded together terminating into Cajon VCR- fittings. • Central 6mm tube is a soft quality stainless tube laying free in outer tube. Inner tube does not have to be centered. • Routing is optimized to have a minimum of height variation (3.5 meter maximum) • Tube assembly is insulated with 25mm Armaflex-NH and supported with Armafix supports

  24. Concentric transfer line (Con’d) • Features: • Outer and inner tube assembly can be bend together without the risk of a buckling inner tube. • Tube conditions: • Outer annular tube is a two-phase mixture with ca. 30% vapor and 70% liquid (mass fractions) CO2. • Operational temperature range -10ºC/-40ºC • Maximum design pressure 100 bar. • Estimated environmental heat leak 300W. • Needed tooling: • Manual or Orbital welder (Swagelok Series 5 or 10) plus tube preparation tools. • Ordinary bending tool for 16mm (r=TBD) • And whatever is needed for normal pipe routing installation.

  25. Ø4mm Ø6mm VTCS Transfer Tubes Protective cover 25mm Armaflex NH Isolation Ø14mm Ø16mm Ø65mm Sub-cooled liquid feed line 2-phase return line

  26. Rack installation path Rack platform (250 kg/m2) A: Installation through shielding wall door on wheels. B: Lifting through lids of platform alleys. C: Rolling onto platform (Surface levels?) C Lifting access Hatch 100x120 B A Access door 85x195

  27. VTCS rack at RB-84 2000 1800 high 950 Envelope dimensions: 2000x950x1800 Concentric tube terminal