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SPD-cooling status

SPD-cooling status. Rosario Turrisi INFN Padova. Foreword: working principle. Evaporative system Joule-Thomson cycle: sudden expansion + evaporation at constant enthalpy Fluid: C 4 F 10 Dielectric Chemically stable Non-toxic. liquid pressure ≡ flow gas pressure ≡ temperature.

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SPD-cooling status

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  1. SPD-cooling status Rosario Turrisi INFN Padova

  2. Foreword: working principle • Evaporative system • Joule-Thomson cycle: sudden expansion + evaporation at constant enthalpy • Fluid: C4F10 • Dielectric • Chemically stable • Non-toxic liquid pressure ≡ flow gas pressure ≡ temperature

  3. Simplified schema Detector side • 2 filters (60 μm) before SPD, in PP4, PP3 • Read-out of p,T per line up- (PP4) and downstream (PP1) the detector • Detector side not accessible, except PP4, PP1 Plant side

  4. Actions taken • Additional heat exchangers to further subcool the fluid close to the detector • 10 HX’s (one per line), redundant exchange factor (more than 5 times) • use leakless system with water cooled down at 7.5 °C • Installation of new liquid-side pipes • dedicated path of new lines, more straight (less elbows), shorter • inox SS316L, 6/4 o/i diameter (same as before) - no insulation (useless) • Flushing each line counter-flow wise • drain particles clogging the filters outside the line • redundant protection against overpressure: 2 safety valves (mechanical) + pressure switch (electronic) • 2 filters, stainless steel, 1 μm grid, on the “washing machine” • 24 h washing cycle per each sector

  5. Room for improvement? From LHCC meeting November 16 • Out of 10 “missing” 9 half-staves have cooling issues • Beyond the number of hs, SPD needs also stability • Following actions need to be taken on solid base, understanding the behaviour in running conditions (lots of variables play...) • Actions for the short term: • remote control of water flow • installation of per-line flowmeters and pressure regulators • repeat the cleaning on worse sectors (7,9) for longer time notneeded The real schedule is of course dependent on when/how long we’ll have access to the experimental area...

  6. ‘Ice age’ test #2 • We wanted to verify if subcooling the freon can help the performance on “critical” sectors (#7 & #9) • We installed in PP4 (close to SPD) ~8 m of plastic pipe in a bucket filled with snow • freon reached ~8 °C in PP4 • Test done on the two worst sectors (#7 and #9) • No significant change of the performance observed Valuesof the bus current for the 6hsof side A - missingmeans off

  7. Measurement of flow flow [g/s] • We measured the flow on a few sectors with a single flowmeter (on a common line) • Better understanding of the performance can be achieved measuring the flow (and then the impedance) by a non evaporating fluid (we’ll use C6F14) • Special care to be taken, the non-evaporative flow prevents control of the pressure inside the detector but by regulating the input • Will be done as soon as we can have a reliable readout of flow and the cleaning of the “bad” sectors is done (use the same device) good p [bar] bad

  8. New hardware - 1 • Pressure regulator on each line: • allows a dedicated tuning of liquid pressure → flow • Flowmeter on each line: • allows the monitor of the flow → fundamental for performance monitoring along the lifetime of the system and debugging of possible problems • Hardware installation completed (sensors + cabling) • Readout system close to completion (next week), integrated in DCS

  9. New hardware -2 • Pressure regulators: Swagelok KPR series, stainless steel with dedicated “peek” gaskets • Flowmeters: Bronkhorst ‘Mini Cori Flow’: • very expensive but necessary to handle the low flows of SPD • based on Coriolis-forces effects, no needles/balls/whatever in the fluid path

  10. A few pictures...

  11. Planning to week 4 Commissioningdelayedto week 4 (25th-29th Jan) toallowlongercleaningofsectors #7 and #9 today

  12. Critical tasks to week 4 today Commissioningdelayedto week 4 (25th-29th Jan) toallowlongercleaningofsectors #7 and #9

  13. Summary • Hardware upgrade of the system completed • A few maintenance interventions to go • Cleaning of the worst lines ongoing (sects. #7 & #9) • By the end of January: • measurement of the flow with non-evaporating fluid • commissioning

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