TCP.B6L7.B1: analytical and numerical evaluation of unexpected heating

1. LHC Collimation Working Group - 10.09.2012 TCP.B6L7.B1:analytical and numerical evaluation of unexpected heating M. GarlaschéA. Bertarelli, F. Carra, M. Calderon, A. Dallocchio, L. Gentini

2. TCP Geometry Ref. dwg LHCTCP__0002 Glidcop 304L stainless steel AC 150 Carbon-Carbon 2x T-sensor Pt100(Al2O3case) CuNi EN-MME-PE Marco Garlasché

3. Temperature Data Pt100 readout sets: Interestingintervals T [C] 17th July 27th July T [C] time time • ISSUES: • General unexpected heating up • Cooling down times in the order of days • Inconsistency between T sensors (left vs. right; left upstream vs. downstream) 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 EN-MME-PE Marco Garlasché

5. Unexpected heating – active cooling? the model used.. • Analytical fit of T data (17th July) • Only active cooling (i.e. convection from water flow in pipes) Fit with only convection (unphysical) leads to heat transfer coeff. values around 4.5 W/m2K (in the range of free convection..) Active cooling is not present! EN-MME-PE Marco Garlasché

6. Unexpected heating – what about only radiation? the model used.. • Analytical fit of T data (17th July) • Only radiation • 1 jaw considered • Consistent material data εSS=0.3 εCC=0.7÷0.9 εCu=0.05÷0.15 1 JAW ‘Only radiation’ condition is compatible with T data! TAMB QRAD TANK EN-MME-PE Marco Garlasché

7. Unexpected heating – what about only radiation? • Symmetric FEM analysis • Power on absorbers such that initial temperature is met in correspondence of the T sensor (*) Except cooling pipes in case 3 • Results consistent with an. estimation • WE CAN RULE OUT: • Case 1 – out of range P and t intervals.. EN-MME-PE Marco Garlasché

8. Unexpected heating – what about only radiation? • Case 3 with reduced active cooling (1 W/m2K) • WE CAN RULE OUT: • Case 3 - not an equilibrium condition EN-MME-PE Marco Garlasché

9. 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. TANK Case 2 Case 4 • WE CAN RULE OUT: • Case 4 – less likely, low P values EN-MME-PE Marco Garlasché

10. Inconsistency of left jaw temperature data EN-MME-PE Marco Garlasché

11. Left jaw Temperature data T [C] Can inconsistency be given by eccentric P deposition? Case 2 time I.o.t obtain similar T, deposition should be completely eccentric… PLEFT=0 W PRIGHT=9 W Is inconsistency given by detached T sensor? Case 2 No contact Contact Absence of contact causes only tenths of degree difference EN-MME-PE Marco Garlasché

12. Left jaw Temperature data T [C] • Left Jaw max temperatures and cool down profile are not compatible with nominal cooling condition • absence of active cooling time • Cool-down curve of left jaw should ‘quickly’ meet the one of right jaw.. EN-MME-PE Marco Garlasché

13. CONCLUSIONS • Unexpected 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? EN-MME-PE Marco Garlasché