IBL temperature analyses Bart Verlaat 22 April

IBL temperature analyses Many steady state situations have been analyzed and compared with CoBra models –IBL powered vs unpowered operation –Several set-points Analyses of the ambient heat loads Boundary conditions from data to CoBra –Flow –Inlet temperature –Outlet pressure –Ambient temperature (Taken from cable temperature) –Ambient heat transfer in CoBra was matched to get similar results on ambient heat. Convective HTC: W/m2K Applied in CoBra: 35 W/m2K (Note that there is also direct contact in reality) Large offsets of the detector temperatures (NTC) have been observed. –NTC are calibrated in situ. Next steps: –Apply Bake-out measurements to CoBra as extreme case. 2

Thermal chain from detector to cooling system The pressure drop causes a temperature drop which depends on the received heat load. –Therefore the cooling pipe CO 2 temperature is not constant and has a heat load depended offset wrt the cooling set point 3 For the 14 staves the return manifold is the common temperature boundary Heatload + ambient SiliconC-foam Pipe wall CO 2 in tube Manifold CF-sheet Th. paste Glue HTC Flex line ΔP Accumulator = set point Transfer line ΔP UX15USA15 Ambient Offset wrt set-point temperature

The IBL CO 2 cooling system 4 Sensor label Stave # Flow dir Connected to stave a1A-C14 b2C-A3 c3A-C2 d4C-A5 e5A-C4 f6C-A7 g7A-C6 h8C-A9 i9A-C8 j10C-A11 k A-C10 l12C-A13 m A-C12 n14C-A1 xCooling system yAverage of all zCommon

Understanding the temperatures in IBL We had large offsets in the temperatures in the IBL –With respect to the CoBra model –With respect to common sense Investigation started to find out what was wrong 5 The offset between the close DCS and Cooling sensor make no sense (Calibration error?) Offset due to pressure drop and/or calibration

Cooling pipe NTC’s showed an offset wrt expectation The DCS NTC sensors show higher values than expected. A study of the data generated in the commissioning period was started to understand the nature of the offsets The used B-formula relation of the NTC show offsets up to 2°C at low temperatures with respect to the more accurate Steinhart-Hart method. The comparison of DCS and cooling neighboring sensors suspect another offset relation. –A recalibration of the cooling pipe and manifold sensors was done. 6 Reading from DCS and cooling system should be similar Offset of the used B-formula relation to the more accurate Steinhart-Hart relation

Calibration of cooling pipe NTC’s in sector 5 7 Connect 2 NTC ‘s to the patch panel near manifold box Connect 1 PT100 to the junction box and archive the data using the cooling system Cool the sensors all together in glycol bath

Copper block with a PT100 and 2 NTC sensors dipped in cold glycol stored in a Dewar. Tube to give a dry passage for wires. Dewar Calibration setup The glycol was cooled to -40ºC and warmed up slowly over time to calibrate over the full range

NTC offset measurement 2 NTC’s were cooled together with a PT100 in a cold glycol bath of initial -40°C. The full temperature range to room temperature was measured using the ambient heating of the Dewar. It took 3.5 days to go from -40°C to 21°C. 9 Offset in the calibration from the B-formula to Steinhart-Hart Opening of Dewar to speed up heating

Recalibration results 10 Measured offset of cooling pipe sensors Offset of B-formula (Now used in analyses) The offsets we see are due to a wrong calibration.

The ambient heat load in the IBL The gradients in the IBL depends on the heat load. –Detector dissipation –Ambient heat leak To compare the simulations with the IBL data the ambient heat like must be taken into account. There is a signature for the total adsorbed heat: –The enthalpy difference between x08 and x46, when x46 is in single phase –This is the total ambient heat leak of the IBL and the transfer line Estimating the IBL ambient heat leak –Previous data from junction box tests was studied to get an idea of the transfer line heat leak. –The measured ambient heat leak corrected with transfer line ambient heat leak prediction gives an rough estimate for the the IBL ambient heat leak. 11 UX15 Transfer line ambient heat leak relation

IBL Detector heat loads (measured and simulated) 12 CoBra HTC=35 W/m 2 K The measured IBL heat leak is in the same order as the transfer line heat leak

The concentric flex line 13 The heat exchange between in and outlet matches the liquid temperature to the outlet 2-phase gradient

The concentric flex line 14 The heat exchange between in and outlet matches the liquid temperature to the outlet 2-phase gradient

The concentric flex line 15 The heat exchange between in and outlet matches the liquid temperature to the outlet 2-phase gradient Indeed a good match

Set point = -30°C 16

Set point = -25°C 17

Set point = -20°C 18

Set point = -15°C 19

Set point = -5°C 20

Detector temperature offsets wrt set point 21

Temperature sensor offsets wrt CoBra model 22

Conclusion The temperatures in the IBL look reasonable when the NTCs are corrected: –The module NTCS corrected with Steinhart- hart instead of the B-formula. –The cooling pipe sensors with the calibration performed by the cooling team The cooling pipe temperature has an offset wrt the cooling set-point. The offset is heat load and temperature depended. 23