Graham Beck 6 Feb 2015 1 Thermal QC Options for the Bare Stave/Petal Core This is about thermal QC , i.e. during production. Aims Primary: Verify that the core functions thermally i.e. will remove module heat. Secondary: Check mechanical integrity (thermal signature of stave construction faults ). QC tests - will be made on every stave / a fraction / none? … depending on yield and experience. - should cause minimal damage/degradation (e.g. non-contact measurements). - should be made with ~ identical systems, that users are happy with, across sites. Possible Tests : Please suggest additions / alternatives / details (e.g. T ranges) ! 1) Thermal Performance: Fluid through pipe (e.g. CO 2 at operating T) + Surface thermal load (to mimic modules). Measure surface T distribution. 2) Thermal Cycling: e.g. -40C to +40C, followed by thermal/mechanical tests (tbd). - from this morning’s Freiburg summary (Sergio): -35/-40C to T g (+30/50?) 3) Thermal Shock: Robustness against Power and/or Coolant ON OFF + accidents!
Transcript
Graham Beck 6 Feb 2015 1
Thermal QC Options for the Bare Stave/Petal Core
This is about thermal QC , i.e. during production.Aims Primary: Verify that the core functions thermally i.e. will remove module heat. Secondary: Check mechanical integrity (thermal signature of stave construction faults ).
QC tests - will be made on every stave / a fraction / none? … depending on yield and experience. - should cause minimal damage/degradation (e.g. non-contact measurements).- should be made with ~ identical systems, that users are happy with, across sites.
Possible Tests: Please suggest additions / alternatives / details (e.g. T ranges) !
1) Thermal Performance: Fluid through pipe (e.g. CO2 at operating T) + Surface thermal load (to mimic modules). Measure surface T distribution.
2) Thermal Cycling: e.g. -40C to +40C, followed by thermal/mechanical tests (tbd).
- from this morning’s Freiburg summary (Sergio): -35/-40C to Tg (+30/50?)
3) Thermal Shock: Robustness against Power and/or Coolant ON OFF + accidents!
Graham Beck 6 Feb 2015 2
Issues: • Expect flow rate LOW for 2mm id pipe (BNL to check full length sample) >5C T rise around loop. [FD flow calcns ok to ~ 20%. htc ≈ 4000 W/m2K ]!! Worse performance for equivalent chiller in Europe (50Hz cf 60Hz).
• Precision IR measurements of absolute T unlikely: camera systematic errors (~ 4C vignetting, narcissus – also known to QMUL).
•Thermal load poorly defined - but expect very similar to module load.Providing flow is acceptable, GOOD for comparative tests + finding localised faults.(Note BNL core pressure test does not check foam-pipe joint).
Thermal Performance Test. What we have so far: BNL • Chiller circulating LIQUID (hfe7100 ) at -35C. 6bar?• Thermal load from ambient (box flushed with N2)• Surface T from scanned IR camera: – NON-contact!
- Clearly can detect missing glue between facing and foam (built-in faults, ≥20mm long).
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WARM liquid: A potentially quick, first stage QC of thermal performance.
e.g. hfe7100 at +40C (chiller). Q transfer to ambient ≈ 30% module heat.Simple set-up: no N2 box, easy IR viewUseful so far, flowing water (eventually must replace by hfe due to corrosion concern).
Stitch-up of ~ 12 IR thermograms (each distorted due to ~20° viewing angle) US Stave250 (foam sealed with BN/Hysol , CGL joint) looked uniform
UK Plank7 : unreliable joint between foam and pipe or facing? (3C wobbles, confirmed by TCs. Not seen on reverse face)
camera was eventually tilted!
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Alternatives: • BNL-like Chiller + hfe7100 (in cooling pipe). In principle much faster (if well insulated).T Range: -35C to +50C. (lower T possible, see later).
• TRACI Evaporative CO2 (if adequate control) : -40 to about +15C only. For higher T need heating elements too.
Thermal Shock not investigated, but expect possible with either CO2 or Chilled liquid.
Thermal Cycling (Freiburg summary (Sergio): environmental chamber ok for petals, difficult for staves)QMUL “Coffin”: custom built environmental chamber.Cooling by liquid N2 dewar boil-off (77K). Switched (noisy).Heaters. Fanned circulation. Large volume (stack several staves).Convective exchange with surface => ±50°C cycle takes 1 hour.
Doesn’t rely on cooling tube => useful for bus tapes etc pre-assembly (but a cooling tube based chamber could be faster?).
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Liquid hfe7100 Bi-phase CO2 Lytron Chiller (AMS) TRACI Blow-off
Stave T range (C, approx.) -35* => +50 -40 => +15
Pressure [bar] 6 10 – 50
Programmable ? Yes Yes (tbc) No !(e.g. for Thermal Cycling) (but need heaters?)
Other advantages Off-the-shelf, Moderate P. CO2 – as ATLAS
Other problems Low flow rate (add aux. Build effort ! Build effort ! pump: HighP/LowT spec!) User friendly? Need bottle bank?
• Capability can usually be extended by investing £££s + technical expertise (where available).• TRACI capabilities to be discussed with Lukasz Zwalinski (ff. feedback from today).• What is minimal acceptable thermal QC? • What is best combination of test apparatus using Liquid (chiller), Gas (N2 cycling) and bi-phase
(CO2) ? Need a plan – solution will depend on QC requirements (need agreement on these)
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Example of a non-production QC setup:UK Thermomechanical Stave (2010) + Blow-off CO2.
Destructive: glued dummy modules + ntcs.
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BNL BN-Hysol samples for thermal conductivity measurement.(Centrifuged to de-gas. Room temperature cure . . .)
• On-going effort to ensure understand IR systematics (background, response..)
• Need more equal DTs sample vs tower: Replace Cu (385) by Pb (35.3) W/mK)
Graham Beck 6 Feb 2015
T vs height
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Laser surface height measurement ( two of slides from Dave Lynn, Jan 2015)- Detects built-in missing glue faults (plus maybe an unintentional one!...) - working on speeding up + reducing noise spikes
