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Bart Verlaat Nikhef CO 2 Kick-off meeting 9July 2009 @ Nikhef

Experiences with CO 2 cooling hardware and applied designs. Experiences from past CO 2 systems and philosophies for the future. Bart Verlaat Nikhef CO 2 Kick-off meeting 9July 2009 @ Nikhef. Scope of the presentation.

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Bart Verlaat Nikhef CO 2 Kick-off meeting 9July 2009 @ Nikhef

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  1. Experiences with CO2 cooling hardware and applied designs.Experiences from past CO2 systems and philosophies for the future Bart Verlaat Nikhef CO2 Kick-off meeting 9July 2009 @ Nikhef bverlaat@nikhef.nl

  2. Scope of the presentation • This presentation will summarize the design solutions as they were successfully applied in LHCb or other lab experiments. • As the presented technologies worked well, they can be used as a guideline for future CO2 systems. • Experiences from the past has set a standardization at NIKHEF for the design of the future plants bverlaat@nikhef.nl

  3. Pressure design issues • Within the EU pressure systems above 1.5 bar absolute must comply with the Pressure Equipment Directive (PED) for the design and fabrication. • Will CERN / ATLAS follow these PED regulations? • It is best to take any regulation into account during the design. • Nikhef is investigating these implications for the CO2 system design, since pressure systems designed and used at Nikhef must comply with the PED bverlaat@nikhef.nl

  4. PED Classification (1)(Pressure Equipment Directive) PED classification for CO2 systems. MDP = Relieve pressure > (P @ TenvMax + 5 bar(start-up) + dPpump)x110% PTP = 1.3 x MDP MDP = Maximum design pressure, PTP = Proof Test Pressure 24ºC => (63 bar + 5bar +10bar)x110% = 86 bar => MDP= 90 bar => PTP = 120 bar Components with non dangerous gasses Tubing with non dangerous gasses 0.55 2.2 11.1 33.3 32 100 250 bverlaat@nikhef.nl

  5. PED Classification (2) Largest component determines the overall component category (Thus a blow system is category IV!) bverlaat@nikhef.nl

  6. Heaters • Heaters in an insulated cooling system are dangerous • (High power + failing cooling = burning insulation). • At Nikhef we always use 2 independent thermal switches to prevent overheating. • At least 1 hardware switch. • Long heaters (like cooling pipe dummies with heaters), an additional smoke detector as interlock is recommended, as the hotspot can be anywhere. • Good experience in LHCb with Watlow fire-rod heaters with epoxy seal. bverlaat@nikhef.nl

  7. Valves • Good experience with Swagelok 43G ball valves. (2-way and 3-way) • -53ºC /172 bar • Nikhef has designed a handle extension for the 43G so warm panel mounting is possible. Ideal way of supporting the tubing structure. • 1 design for manual and automatic control • T-shape hole to avoid liquid trap • SS-43GHLVCR4 Electrical Control replaces manual knob bverlaat@nikhef.nl

  8. CO2 pumps (1) Spring Damper • Good experience with the LEWA LDC1 metering pump in LHCb. • Modifications made for LHCb: • Spring loaded outlet valve (0.8 bar), normal for high viscous fluids • Heated oil bath to prevent moisture • (Toil=18ºC) • Dismountable isolation for easy access • LEWA pump gives pulsations • Gas damper • Gather gear pump under investigation for test plant • No pulsations • Smaller pump • First result: pumps well, but after 2 weeks in CO2 the gears got blocked due to swelling (PPP). New gear material under investigation. Isolation T=18ºC Q=130Watt Heater Lewa pump in LHCb bverlaat@nikhef.nl

  9. CO2 pumps (2) Gather gear pump Lewa membrane pump bverlaat@nikhef.nl

  10. VTCS Accumulator Cooling spiral for pressure decrease (Condensation) Thermo siphon heater for pressure increase (Evaporation)

  11. CO 2 Accumulator Liquid level Over critical filling Under critical filling 2PACL filling 2PACL Start-up Decrease heater power near critical point to prevent dry-out. Higher vapor density cause less convection. • Single-phase cold operation is worst-case for minimum level • (Heater need to be submerged all the time) • Two-phase cold operation is worst-case for maximum level • (Significant part of the cooling coil need to be in vapor phase)

  12. Accumulator for lab experiments The easy way: Completely submerge a vessel in water-glycol controlled by a thermostatic bath. (The AMS-TTCS test set-up way) bverlaat@nikhef.nl

  13. Heat exchangers The reinforced heat exchanger is now commercial on the market. (limited to -10ºC because of steel plates) Reinforced heat exchangers in LHCb (135 bar) bverlaat@nikhef.nl

  14. Connectors and tubing • Swagelok VCR connectors • Easy to assemble and reassemble • Easy to leak test • Very reliable • All tubing is 316L and matching the Swagelok orbital weld connector series dimensions. • More choice in imperial units, so tubing is standardized imperial as well. • 1/8” x 0.028” (1/8” VCR-2 connector, 573 bar) • 1/4” x 0.035” (1/4” VCR-4 connector, 360 bar) • 3/8” x 0.035” (1/4” HVCR-4 connector, 240 bar) • 1/2” x 0.049” (1/2” VCR-8 connector, 180 bar) bverlaat@nikhef.nl

  15. Orbital welding • As many joints as possible by orbital welding. • Very reliable connection method. • Light weight bverlaat@nikhef.nl

  16. Insulating • ¼” VCR (1/4” tube) and HVCR (3/8” tube) have connector diameter 19mm • Most other hardware is selected to match ~19mm. • Tubing is isolated to ø18mm • The rest is insulated with Armaflex NH 25-018 • Important: Air tight glued assembly to keep moisture out! Ø18 Ø68 Ø18 bverlaat@nikhef.nl

  17. Control and Monitoring • PLC control development (Siemens S7) • In house development of PVSS projects • Both for laboratory set-ups and for real slow control at experiments (LHCb) LHCb-VTCS PLC rack LHCb-VTCS PVSS interface bverlaat@nikhef.nl

  18. Safety relieve 720 bar • Trapped cold liquid is a real danger in a liquid cooling system. • Every volume need a relieve • Swagelok SS-RDK-16-1900 (130 bar) miniature rupture discs works well. • Relief valve SS-4R3A, has decompression problems of o-ring. New o-rings under investigation bverlaat@nikhef.nl

  19. Thanks for your attention:Questions? bverlaat@nikhef.nl

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