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TCP.B6L7.B1: ANALYTICAL AND NUMERICAL EVALUATION OF UNEXPECTED HEATING
LHC Collimation Working Group - 10.09.2012
M. GarlaschéA. Bertarelli, F. Carra, M. Calderon, A. Dallocchio, L. Gentini
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EN-MME-PE Marco Garlasché 2
TCP Geometry
04/09/2012
Ref. dwg LHCTCP__0002
2x T-sensorPt100(Al2O3case)
Glidcop
CuNi
304L stainless steel
AC 150 Carbon-Carbon
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EN-MME-PE Marco Garlasché 3
Temperature Data
04/09/2012
ISSUES:• General unexpected heating up• Cooling down times in the order of days• Inconsistency between T sensors (left vs. right; left upstream vs. downstream)
17th July
27th July
Interesting intervals
Pt100 readout sets:
T [C]
time
T [C]
time
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EN-MME-PE Marco Garlasché 4
Summary
Unexpected heating:
Analytical evaluation of possible cooling conditions (active cooling vs. radiation) FEM validation (static & transient) Analytical estimation of instant power deposition
Inconsistency of left jaw temperature data
Eccentric P deposition? Positioning of sensors?
Conclusions
04/09/2012
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EN-MME-PE Marco Garlasché 5
Unexpected heating – active cooling?
Fit with only convection (unphysical) leads to heat transfer coeff. values around 4.5 W/m2K (in the range of free convection..)
04/09/2012
Active cooling is not present!
• Analytical fit of T data (17th July)• Only active cooling (i.e. convection from water flow in pipes)
the model used..
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EN-MME-PE Marco Garlasché 604/09/2012
Unexpected heating – what about only radiation?
QRAD
TAMB
εSS=0.3εCC=0.7÷0.9εCu=0.05÷0.15
• Analytical fit of T data (17th July)• Only radiation• 1 jaw considered• Consistent material data
‘Only radiation’ condition is compatible with T data!
TANK 1 JAW
the model used..
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04/09/2012 EN-MME-PE Marco Garlasché 7
Case Active Cooling
Contact between absorber & other components (*)
P [W] needed for constant 65°C
1 √ √ 4300
2 X √ 13
3 √ X 14
4 X X 7
Unexpected heating – what about only radiation?
• Results consistent with an. estimation• WE CAN RULE OUT:
Case 1 – out of range P and t intervals..
(*) Except cooling pipes in case 3
• Symmetric FEM analysis• Power on absorbers such that initial
temperature is met in correspondence of the T sensor
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EN-MME-PE Marco Garlasché04/09/2012
• WE CAN RULE OUT:Case 3 - not an equilibrium condition
Unexpected heating – what about only radiation?
• Case 3 with reduced active cooling (1 W/m2K)
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EN-MME-PE Marco Garlasché 904/09/2012
Unexpected heating– instant power deposition• Only case 2 & 4 analysed• Upgraded analytical model considers presence of other jaw• P deposition per jaw at different jaw gaps determined starting
from T data (17th-24th July) • Model benchmarked with estimations (B. Salvant) from RF
induced power loss.
Case 4
• WE CAN RULE OUT:Case 4 – less likely, low P values
TANK
Case 2
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EN-MME-PE Marco Garlasché
INCONSISTENCY OF LEFT JAW TEMPERATURE DATA
04/09/2012
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EN-MME-PE Marco Garlasché04/09/2012
Left jaw Temperature data
Can inconsistency be given by eccentric P deposition?
PLEFT=0 WPRIGHT=9 W
I.o.t obtain similar T, deposition should be completely eccentric…
Case 2
Is inconsistency given by detached T sensor?
No contactCase 2
Contact
Absence of contact causes only tenths of degree difference
T [C]
time
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EN-MME-PE Marco Garlasché04/09/2012
Left jaw Temperature data
• Left Jaw max temperatures and cool down profile are not compatible with nominal cooling condition
absence of active cooling
T [C]
time
• Cool-down curve of left jaw should ‘quickly’ meet the one of right jaw..
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EN-MME-PE Marco Garlasché04/09/2012
CONCLUSIONSUnexpected heating:
High T & long cool down intervals, nominal option (1) not possible Absence of equilibrium and low estimated P, option 3 & 4 not likely
Most likely option is nominal contact between components and no active cooling (i.e. heat evacuation only through radiation)
Good agreement between analytical and FEM evaluations
Inconsistency of left jaw temperature data
No active cooling also on left jaw TLEFT vs. TRIGHT : eccentrical P deposition highly unlikely Tupstream vs. Tdownstream :sensor not in contact with jaw may only partly cause difference
Sensor not working properly? Readout calibration?
