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Cooling Update (May 2011)

Cooling Update (May 2011). Tim. Overview. From last time Estimate Power Loads Active components Extraneous heat sources Develop methodology for exploring c ooling system parameter space Flow rate Pressure drop Pipe bores Control and Monitoring Strategies Implementation.

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Cooling Update (May 2011)

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  1. Cooling Update(May 2011) Tim

  2. Overview • From last time • Estimate Power Loads • Active components • Extraneous heat sources • Develop methodology for exploring cooling system parameter space • Flow rate • Pressure drop • Pipe bores • Control and Monitoring • Strategies • Implementation Cooling Update

  3. Power Estimate • FE • 32 PMTs per array • 4 arrays per cooling circuit connected in series • 0.5W per PMT • 16W per PMT array, 64W for four arrays on one side • Environment • Box dimensions 1.2(h) x 0.6(w) x 0.3(d). • Area of 5 sides = 2.16sq.m • Box insulation k=0.05 W.m-1.K-1 • Wall thickness 50mm • Assume external wall is at 40C and internal wall is at 20C • Power = 0.05 x 2.16 x 20 / 0.05 = 47W • Total Power • 64 (FE) + 47(env) = 107W Cooling Update

  4. Pipe-work Geometry • External Interconnect • Flow and return lines 7m long with a bore of 12mm • Internal • Heat exchanger: heated length 0.5m per array • Interconnect: 4m in total • Bore: 4, 6, 8mm Cooling Update

  5. Draft Chiller Requirements • Tabulate Flow and pressure for different bores of the internal pipe work and desired temperature rise • Chiller Specifications (preliminary web-trawl) Cooling Update

  6. Control • Issues • Maintain the PMT arrays at a given temperature • Control the heat transfer between the box and the CEDAR • Options • Control the PMT array temperatures such that the global temperature of the box is close to the CEDAR. Provide sufficient thermal insulation to minimise coupling between box and CEDAR. • Monitor the CEDAR temperature and control the temperature of the PMT arrays such that the temperature difference between the box and the CEDAR is minimised. • Control the PMT array temperatures such that the global temperature of the box is just below the CEDAR. Provide an ACTIVE thermal enclosure between the box and the CEDAR and control the temperature on the CEDAR side to minimise heat flow. • Need more engineering input to define interfaces between CEDAR and box Cooling Update

  7. Option 1 Cooling Update

  8. Comments • Option 1: • Likely to need greatest number of interventions to adjust chiller PID controller • Needs chiller with in-built heater • Needs high precision chiller set-point & stability • Option 2: • Highest cooling power requirement • Need to develop fault tolerant PLC /heater sub-system • Option 3: • Chiller may not need in-built heater • May allow low precision chiller set-point & stability • Complete segmentation of control sub-systems • Needs detailed engineering analysis / design & manufacture of active thermal enclosure Cooling Update

  9. Chiller Issues • Issues • Radiation field • What’s the annual dose ? • What’s the chiller operational lifetime? • Condenser motor, water pump • PID controller • Fittings, gaskets, seals … • Explosion • Chiller located ~ 7m from CEDAR • If chiller is in a N2 flushed enclosure how does it expel the heat generated? • Options • Specify a bigger chiller to stretch flow/return pipework to safe(er) area • How big a chiller, long are the pipe runs, cost? • Improves access to the controller • Minimises future risks • Replace chiller PID controller with a connector/cable & re-locate PID controller to safe(er) area • Probably needs discussion with manufacturer, will result in ‘non-standard’ unit, cost? • Improves access to the PID controller • Select a chiller with a readily available PID controller & replace it periodically • What’s the interval ? Cooling Update

  10. Eg. Chiller with a standard PID • Grant RC350G • Nearly meets 0.25C inlet to outlet temperature rise spec. • Controller • Eurotherm 2132 • RS • Stock number 208-2739 • £161 + VAT Cooling Update

  11. Eg – Remote Chiller • Assume flow = return = 50m • Extra Power • Assume 25mm insulation (k=0.04) and a T = 40C • Power ~ 130W • Recall that conservative estimate for internal power is 107W (FE + ambient) – so need 250W • Pressure Drop • Internal 1.71bar for 6mm bore • External pressure drop vs bore • Need large bore for low dP but is transit time an issue for control? Cooling Update

  12. Eg. Large(r) Remote Chiller • Huber UC012 • -10 to 40C • 25lpm (0 head) • 2.5bar (max pressure) • 1.2kW @ 15C • 3870 Euro • Popular at CERN • Nearly OK • would need to reduce flow/return tubing length • Increase internal tubing to 8mm • Allow larger dT Cooling Update

  13. Thermo-NeslabThermaFlex 900/P2 • 750W @ 20C • 10lpm @ 6bar • £3,200 Cooling Update

  14. Summary • Investigate if remote chiller is possible • Location • Pipe-work lengths / routing • Update flow parameters • Investigate chillers • Back-up • Not sure there is one! • How does an air-cooled chiller dissipate heat if it’s in an ‘sealed’ enclosure for H2/explosion proofing? Cooling Update

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