1. cooling for BGV modules
trying to collect information
toward a specification document
Mostly of the cooling system, i.e. chiller+transfer line with given loads (not specifying the module cooling interface, which is considered fixed, designed by EPFL)
thanks to Petr Gorbounov
see also his contribution in

2. Help from EN-CV ? Talked to Michele Battistin (18 dec 2013)
They have no resources for integration/installation on short notice
But they can help for dimensioning and technical contact with companies
They need some specs: cooling strategy, a sketch, acceptable T over modules, operating temperature at detector, acceptable temperature gradient over transfer line, pressure drop at detector (pipe diameter, series or parallel ?)
Integration: I. Muttoni
Note: Julabo chiller is good, must however ask perhaps for special pump (depending on required flow)

3. BGV module dry air in/out fiber mats electronics/flex ~26cm
cooling fluid in/out
thermal-insulating box
(contains SiPM detectors that need to be kept cold)

4. BGV system composed of 8 modules,
arranged in 2 stations (distance between stations is about 1m)

5. transfer line

6. Side view inter-tunnel connecting hole

7. transfer line request to be measured in lab as soon as possible
General:
Single phase liquid cooling
Type of fluid: 3M NOVEC 649 or similar (radiation! ~ < 100 Gy/year)
not creepy, oily, ... Keep SiPM and electronics clean in case of fluid leaks!!
SiPM cooling pipe (2 per module): in/out diameter = 3/4 mm, 378 mm long, copper
16 pipes in total, connected in series or parallel ... expect suggestion from TS-CV
Operating temperature (at detector): settable between 20 and -40 C
Module inside (SiPM and pipe) is flushed with dry air
Stability +/- 1K , gradient < 1K over one SiPM (thus 8K over one SiPM row ?)
Assume 20 W heat load per module ? (conservative) dominated by heat leaks (insulation)
Transfer line:
Transfer line must be fixed in place, before closure of machine (2014)
Goes from near detector to just outside the connecting hole
Total length (3D path) is about 20m (minimum)
Temperature drop over transfer line < 10 K (to avoid to low chiller temperature)
Insulated, no frost
Acceptable pressure drop over transfer line: don't care ?
Must be dimensioned such as to allow flux of up to 20 l/min
to be measured in lab as soon as possible
turbulent flow: >0.5 l/min per SiPM pipe

8. transfer line: some pictures
machine tunnel side (RA43)
service tunnel side (UA43)
the wall hole

9. sketch of BGV cooling Thermal insulation up to module! tunnel wall
dark box
dry air
station 1
station 2
module
module
service tunnel
transfer line
chiller
tunnel wall
Thermal insulation up to module!

10. backup / notes

11. BGV cooling specs
SiPM pipe:
innner d = 3mm
outer D = 4mm
length L = mm
Assume operating temperature: settable between 20 and -40 C at detector
Stability +/- 1K
Assume 20 W heat dissipation per SiPM module ? (conservative)
to be confirmed by measurement!
Max temperature gradient over 1 SiPM: 0.5 K
Max temperature gradient over 1 branch: 5K
Minimum flow F needed per branch to get turbulent flow:
Take NOVEC:  = g/dm3 at -40C
C = 1.1 J g-1 K-1, k = W m-1 K-1
 = 0.64 cP kin. viscosity = 0.4 cSt
Re = d  v /  = 4  F / (  d ) F = flow = v  (d/2)2
heat transfer coeff:
h = ~ Re0.8 (k/d) Pr = ~0.32 W cm-2 K-1
Pr = C ∙  / k = ~120
q = h ∙ A ∙ (Twall - Tfluid ) A =  d L = 36 cm2
Acceptable pressure drop over transfer line: don't care ? d
velocity
>10000 is turbulent
take Re = 8842

12. LHCb chiller in point 8 (Petr Gorbounov)
example
called Julabo: do not guarantee it works in radiation (10-100Gy/yr)

13. chiller, more power example
called Julabo: do not guarantee it works in radiation (10-100Gy/yr)
get picture at POINT8, what model ?

16. Coolant
C6F14 or NOVEC 649 ?
Try NOVEC 649 and get experience!