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LHCb VELO Meeting

LHCb VELO Meeting. LHCb VELO Cooling System Bart Verlaat (NIKHEF) 25 February 2003. LHCb VELO Cooling System . Verification of the current design (As described in LHCb note 2001-0XX/VELO, July 02,2001). 2001 status overview Primary cooling system (R404A/R507): Capacity: 2.9 kW@-35’C

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LHCb VELO Meeting

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  1. LHCb VELO Meeting LHCb VELO Cooling System Bart Verlaat (NIKHEF) 25 February 2003

  2. LHCb VELO Cooling System Verification of the current design (As described in LHCb note 2001-0XX/VELO, July 02,2001) • 2001 status overview • Primary cooling system (R404A/R507): • Capacity: 2.9 kW@-35’C • Secondary cooling system (R744=CO2): • Pmax: 70 bar • Qdetector: 2.5 kilowatt • CO2 mass flow: 17 g/s • -Tevaporation: -30’C – 0’C • - Warm transport lines. • Adjustable restriction in liquid transport line. • Fixed restriction before 0.9 mm tube: ca. 10 bar. • Heat exchanger between evaporator in and outlet after 1st restriction. E H G F C B A I D bverlaat@nikhef.nl, 29 January 03

  3. Secondary cooling system cycle in the P-h diagram (1). Design status 2001 Liquid heater (AB) Pump (IA) Heat exchanger: HFG=HCD Gas heater (GH) Detector power (EF) Minimum primary cooling capacity: 4362 Watt@-35’C bverlaat@nikhef.nl, 29 January 03

  4. Secondary cooling system cycle in the P-h diagram (2). • Modified status: • Heat exchanger before 1st expansion valve • 140 bar liquid transport Liquid heater (AB) Pump (IA) Heat exchanger: HFG=HAB Detector power (EF) Minimum primary cooling capacity: 3521 Watt@-35’C bverlaat@nikhef.nl, 29 January 03

  5. VELO Cooling overview and optimization • Warm transport has more impact on the design as foreseen, but is possible if: • The primary cooler capacity is increased. • The liquid transport pressure is increased (70 bar is in a very critical region) • The efficiency of the system can be optimized by: • Keeping the secondary refrigerant flow (CO2) to a minimum (See table) • Moving the heat exchanger in the liquid line from CD to AB • Increasing the liquid transport pressure (Current pump limit is 140 bar) • The evaporator flow conditions seem to be in the proper flow regime, but are more critical for dry-out in when the system is optimized. (x=0.83 w.r.t. x=0.68) ( “x” is the vapor quality). Tests have to determine the dry-out limit for the VELO evaporator flow conditions. • If the heat exchanger stays in place the cold gas can be used to cool additionally heat sources on the VELOI. If not applied the cold gas will be heated electrically to avoid conde4nsation on the vapor line. bverlaat@nikhef.nl, 29 January 03

  6. VELO thermal requirements: Silicon Wafers thermal requirements: • Operating temperature range: -10 ‘C/ 0 ‘C LHCb2001-070/VELO • Survival temperature range: xx • Temperature stability: xx • Maximum accepted gradient between sensors: xx • Dissipated heat: 0.03W-0.17W (0.3 W max). LHCb2001-070/VELO Beetle chip thermal requirements: • Operating temperature range: xx • Survival temperature range: xx • Dissipated heat: 2500 Watt total. LHCb2001-0XX/VELO, July 02,2001 External electronics requirements: • External electronics dissipation: 1500 Watt (MVB) Other heat sources: • Corrugated foil heat dissipation: 2.2 Watt/Foil (FK) • Any other possible heat source??? Other temperature requirements: • Module base operational temperature: Assembly room temperature (ca. 20’C) (MD) • Corrugated foil: Lower than environment to get tension instead of compression. (HBR) • Any other temperature requirements??? LHCb environment temperature: 20'C? Any large amount of dissipation near the Vertex? bverlaat@nikhef.nl, 18 February 03

  7. Future activities(Very preliminary) • The shown enthalpy cycles will be verified with a low power test set-up, using the existing AMS-TTCS CO2 system at NIKHEF. • Enthalpy measurements • Evaporator pressure drop measurements • Heat transfer measurements (Dry-out determination) • Based on the test results a baseline design concept will be chosen. • A BBM (Bread Board Model) will be built conform this baseline.

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