Stato del sistema di
raffreddamento del rivelatore SPD
di ALICE
Rosario Turrisi
1
Cooling: working principle

PP1
Joule-Thomson cycle
 sudden expansion + evaporation at constant
PP3
enthalpy

PP4
Fluid C4F10: dielectric, chemically stable, non-toxic,
convenient eos

Nominal evaporation: 1.9 bar, 15°C

heaters
PP=patch panel
now: difficult procurement
capillaries
liquid pump
pressure
condenser
cooling tube
compressor
Filters (60μm)
p, T
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
enthalpy
two ‘knobs’:
9 Luglio
2012
liquid-side pressure
gas-side pressure
2
flow
temperature
The issue
 Performance worsening in time
 Minimum acceptance reached: 62.5%, most because of cooling failure
Start of LS1  <45%
•
•
extrapolation from last year
assumes constant trend
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
3
Critical components

Capillaries (CuNi, 550 mm long, 0.5 mm i.d.)

Cooling pipes
 Phynox, 40 μm wall thickness
 Round 2.8 mm pipes squeezed to 0.6 mm inner size

Inline filters
 Fundamental to protect previous items, 60 μm porosity
 1 accessible during beam stop
 1 accessible dismantling part of ALICE (~6 months job)

(Missing) filter at the plant
 added after 1 year run a 2 μm filter at the liquid outlet
PP=patch panel
SEM picture of the filter
(orange square=1mm2)
no access
X
T
D = 5.6 mm
D
T = 11.8 mm
X = 0.7
mm (~1
mm in the filtering area) 4
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio
2012
Chase the guilty

Search and confirm the cause has been a long and painful process, 4 years long

All procedure tested on a dedicated test bench set up by our team with CERN

Many tests performed

SEM analysis of PP4 filters enlightening…

many particles of several materials, possible origin:




graphite from pumps, weldings, plant’s hydrofilter
The filters mesh has 60 μm size in average

smaller sized particles can be stopped and bigger can go through!

some pollution can pass the first filter and stop on the second
Once clogged, the second (PP3, not reachable) filter causes:

pressure drop

lower flow rate
20 μm
Add the heat-up of the fluid along the supply line, and you have:
poor cooling performance & local inefficiencies
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
5
The hard way: drilling
After several (unsuccesful) attempts (solvents, ultrasounds) we went ‘’the hard way’’ with the
following procedure:
•
•
drilling:
–
tungsten carbide tip welded on 5 m long twisted ss cable, rotated by a drill
–
counter-flow at 200 mbar w/manometer to detect the presence of the hole (~50 mbar drop)
–
takes 2-3’
cleaning:
–
rilsan pipe connected to a rotary vane vacuum pump to aspire the drilling debris
–
walk inside the pipe with a twisted ss cable with a magnetic tip fixed at the end
–
cleaning machine to force counter-flow wise a cleaning fluid
–
repeat several times the previous steps
–
last, let the cleaning machine run overnight (or more) with a 60 m filter to collect particles
–
analyze this filter with an optical microscope and (if needed) the SEM
–
redo the cleaning procedure if not happy
TESTED BY DRILLING > 100 FILTERS !
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
Edwards RV3 rotary vane 2-stage pump
Fiberscope
L=5 m, Ø=1.5 mm
magnet
tungsten carbide 5-faces tip
cleaning machine
Access point
Ø 2.5 mm ss twisted cable
Target point
4.5 m of ss pipe 4mm i.d.
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
7
The drill team
Yannick Lesenechal
Andrea Francescon
Samuel Rambaut
Claudio Bortolin
Rosario Turrisi
Royal straight: five nice cards but the strength is the team!
And we’re well backed by the whole SPD team!
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
8
200 μm
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
9
Clean it!
 Sector #9 drilled on Feb 14
Material collected by
vacuum cleaning after drilling
Material collected after
the cleaning procedure
Analyses by Norberto Jimenez Mena and Maud Scheubel (EN-MME-MM)
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
10
Materials analyses
stainless steel
silicon compounds
(a.k.a. ‘’dust’’…)
fluorine compounds
100 μm
100 μm
100 μm
Analyses by Norberto Jimenez Mena and Maud Scheubel (EN-MME-MM)
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
11
Interventions and results
 Drilled 5 filters: sectors 9 (Feb 14), 7 (Feb 27), 6 (Mar 6), 4 & 5 (TS Apr 23-27)
 Oldest flow rate values from last November
 8 sectors above nominal value
 5 drilled, 3 because of vacuum cleaning
 Last cleaning of sector 3 restored the possibility to turn it on completely!
12 12 11
11 11 10 12
11
12
10
hs on
1.8 g/s = nominal value
new flow rate values
old flow rate values
drilled filters
9 Luglio 2012
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
12
Recovered acceptance
Acceptance changed from this …to this!
65/120 modules ‘’on’’ - 62.5%
snapshot from November 10, 2011
112/120 modules ‘’on’’ - 93.3%
NOW RUNNING
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
cannot be recovered
could be recovered
hot
13
Happy end!

Recovered the cooling system to 100% efficiency
 no more ‘’special maintenance’’ until pPb run (unless needed)

The plan for LS1 changed accordingly: no need to move TPC, ITS, etc. (>6 months job!)
 If needed could do the drilling of the 5 left filters

Finally our soundtrack plays!
…and the SPDer’s
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012
14
TS3 (17-21 Settembre 2012)
•
Test in pressione delle vecchie linee di input (2 pp x 4gg)
Durante LS1 (11 Febbraio 2013 – xx/xx/2014)
1.
Rimozione nuove linee input e subcooling (4 pp x 5gg)
2.
Ripristino vecchie linee (pulizia, connessioni, leak test) (4 pp x 10gg)
3.
Consolidamento rack impianto (CERN EN/CV/DC)
4.
Installazione filtro acqua (CERN EN/CV/DC)
5.
Ricalibrazione valvole sicurezza (CERN EN/CV/DC)
6.
Ricalibrazione sensori temperatura e pressione (2pp x 5gg)
7.
Foratura filtri di 5 settori (dipendente da andamento prestazioni, 1ppx15gg +pers. CERN)
Rosario Turrisi - Stato del sistema di raffreddamento del rivelatore SPD - Consiglio di Sezione
9 Luglio 2012