Summary of thermal management meeting
Summary of thermal managementSummary of thermal management working group meeting, December 6 working group meeting, December 6
PresentationsPresentations• Introduction (G. Viehhauser, Oxford)
• Reutilisation of present tubing plant (G.V.)
• Status reports for different coolants:– Light fluorocarbons (G. Hallewell, CPP Marseille)
– CO2 (A. Colijn, NIKHEF)
• Flow control with thermostatic expansion valves (N. Hessey, FOM/NIKHEF)
• Recent experience from cooling system commissioning (R. Bates, Glasgow)
• From current cooling installation to future CS upgrade for ATLAS ID (V. Vacek, CTU, Prague)
• Thermal Management Issues for Stave Structures (C. Haber, LBNL)
Summary of thermal management meeting
MEANS COOLANTS
Summary of thermal management meeting
Issues: Try to use as much of the existing pipework as possible (mainly the tubing through the magnet to the ID volume) External components on access platforms and in USA15
can be considered less static:
Much hinges on delivery and evaporation pressure of final coolant, impedance to evacuate vapour,
critical temperature of chosen fluid
Summary of thermal management meeting
Operating temperature of silicon detectors
Can we estimate a Si operation temperature for sufficient safety margin @ L>>1034?
From Nobu Unno’s September 6th talk: -30°C on SCT Sensors, requiring (my guess) ~-45C evaporation
in on-detector cooling channels
15°C (Si – coolant) T Reasonable? Conservative?...
Summary of thermal management meeting
Power dissipation of silicon detectorelectronics
No estimate given (anywhere in this conference)of dissipation of electronics
(Given the much higher activity within the electronics+ reduced radius (1/r2) of new B layer, extra track /
background activity at luminosities ~ 1035
Summary of thermal management meeting
The fluids…Two (maybe 3) candidate fluids: C2F6, CO2 & (maybe still) C3F8
A few pros and cons:C2F6: Enthalpy ~ 100J/g, Pevap~ 4 bara @ -45°C, Tcrit ~ 20°C
Liquid delivery pressure in warm zones ≥ 30 bar
CO2: Enthalpy ~ 280J/g Pevap ~ 7 bara @ -45°C, Tcrit ~ 30°CHigher evaporation pressure higher HTCTriple point temperature ~ -56°C (dry ice formation) Liquid delivery pressure in warm zones ≥ 70 bar
C3F8: Enthalpy~100J/g, Pevap < 1 bara*@ -45°C, Tcrit ~ 60°C * low evaporation pressure needs special treatment
Summary of thermal management meeting
ATLAS SCT & Pixels: Principle of present C3F8 system
Vapour h.p.
Vapourl.p.
Liquidh.p.
Liquidl.p.
Déverseur/Back-pressureregulator for
groups of circuits(Individual Pevap)
Performancesqueezed here!
Summary of thermal management meeting
Possible cycle with CPossible cycle with C22FF66
Surface condenser
Evaporation @ -45°C:
CompressorPin~4.5bara, Pout~15bar
Detent
gh liquid return to pit
Atten
Attention: Tcrit ~20°C
ΔH ~ 110 J/g
Summary of thermal management meeting
ΔH(-35C) = 280 kJ/kg
Enthalpy [kJ/kg]
Pre
ssur
e [b
ar]
P = 12 bar
liquid
2-phase gas
CO2 properties: p-H diagram
Attention: Tcrit ~30°CP = 60barAttention: Pdeliv ~ 60bar
Summary of thermal management meeting
Problems with the present CProblems with the present C33FF8 8 systemsystem(Which might require ‘external’ intervention)(Which might require ‘external’ intervention)
(1) Back-pressure regulators contribute substantial (& variable) insertion loss (CV variability) being mastered…;
(2) Significant insertion loss in deeply embedded hex’s, heaters;
(1) & (2) low compressor aspiration pressure (~1barabs)
(3) Very high compression ratio xacross compressors due to the very high choice of condenser pressure;
(1), (2) & (3) conspire to put the compressor in a regime of reduced throughput (pumping speed) and hotter operation
Cooling circuits have little margin for reducing Si temperature. Cooling circuits have little margin for reducing Si temperature. Also compressor cooling less efficient: Also compressor cooling less efficient:
(reduced flow of cooling gas) (reduced flow of cooling gas) expect a reduced MTBF? expect a reduced MTBF?
Summary of thermal management meeting
HEX DCSDetector DCSDet. environmental DCS
Heaters DCS
Off-detector layout, inc DCS
Summary of thermal management meeting
ATLAS pit(d ~ 92m)
ATLAS Surface Buildings
USA15
Remote Control Pressure regulatorsPin ~ 14bar
(flow proportional to heat load)
Compressors
Condensers operatingWith lower input pressure
than in USA15 location
Tracker
Examplegh(liquid)bar(C3F)
Example:gh(vapour)m
bar(C3F)
Toward a simplified circulator with reduced compressor stress(and enhanced compressor M.T.B.F.)
Tubing to be sizedfor dynamic P
Summary of thermal management meeting
There is yet space!
Summary of thermal management meeting
A ‘graded external fix’ approach to A ‘graded external fix’ approach to problems with the present Cproblems with the present C33FF8 8 systemsystem
(Integrable steps in the cooling system for the tracker upgrade)(Integrable steps in the cooling system for the tracker upgrade)
APPROACH (1)APPROACH (1)Eliminate back-pressure regulators +
use compressor aspiration tank pressures (by varying compressor speed using motor speed controller) to control evaporation pressure in pixel and SCT circuits
Moduarity issues?Moduarity issues?
Summary of thermal management meeting
A ‘graded external fix’ approach to A ‘graded external fix’ approach to problems with the present Cproblems with the present C33FF8 8 systemsystem
IF APPROACH (1) DOES NOT SUFFICIENTLY INCREASEIF APPROACH (1) DOES NOT SUFFICIENTLY INCREASESi DETECTOR OPERATING TEMPERATURE MARGIN…Si DETECTOR OPERATING TEMPERATURE MARGIN…
APPROACH (2) Install ‘local’ (COLD C) condensers (service platforms) Condenser cooled either using LN2 /Gfrom liquid argon calorimeter cooling loops or a compressor system (R404A?)
How to circulate CHow to circulate C33FF88 primary coolant back to capillaries?: primary coolant back to capillaries?:
(2-i) Using liquid pumps (hydraulic or pneumatic drive for B field)(2-i) Using liquid pumps (hydraulic or pneumatic drive for B field)
(2-ii) Using 2(2-ii) Using 2ndnd (external) evaporator (external) evaporator & existing Haug Compressors in USA15& existing Haug Compressors in USA15
Summary of thermal management meeting
A ‘graded external fix’ approach to A ‘graded external fix’ approach to problems with the present Cproblems with the present C33FF8 8 systemsystem
IF APPROACH (1) DOES NOT SUFFICIENTLY INCREASEIF APPROACH (1) DOES NOT SUFFICIENTLY INCREASESi DETECTOR OPERATING TEMPERATURE MARGIN…Si DETECTOR OPERATING TEMPERATURE MARGIN…
APPROACH (2) Install ‘local’ (COLD C) condensers (service platforms) Condenser cooled either using LN2 /Gfrom liquid argon calorimeter cooling loops or a compressor system (R404A?)
How to circulate CHow to circulate C33FF88 primary coolant back to capillaries?: primary coolant back to capillaries?:
(2-i) Using liquid pumps (hydraulic or pneumatic drive for B field)(2-i) Using liquid pumps (hydraulic or pneumatic drive for B field)
(2-ii) Using 2(2-ii) Using 2ndnd (external) evaporator (external) evaporator & existing Haug Compressors in USA15& existing Haug Compressors in USA15
Summary of thermal management meeting
USA15
Remote controlpressure regulators
Pin ~ 14-17bar
Haug compressors in USA15
Low temperature condenser operating on GN2 (LN2 boiloff) or else R404a, ex
C3F8 compressor system(Condenser at highest point on ATLAS platforms)
Tracker
Liquid pump (possibly 2-stage):Hydraulic/pneumatic drive for high B-field operation
Must generate ~14-17 bar C3F8 capillary input pressure
2.i Enhancing Si operating temperature margin of the present C3F8 evaporative cooling system
Priming height(maximum possible)
h(liquid)m bar(C3F)
(boosts pump output)
Use Haug compressors tocool local condensers in UX
(no longer in primary cooling loop)
Summary of thermal management meeting
Principle of modified P-H cycle : recovery of present C3F8 system
P (T) between Evaporation & Condensation determined by sizing
of exisiting internal services
Condensation
Evaporation @-45°C
P liquid via(2-stage?)
pump
Pressure regulators & present choiceof capillary (Ø,L)
Summary of thermal management meeting
Fluorocarbons can be mixed (blended ) to arrive at compromise thermodynamic properties
(many modern refrigerants are blends) This was tested with C3F8/C4F10
(2 papers in Fluid Phase Equilibria 2000-2001)
Mixture thermodynamic, transfer properties calculated & set up as ‘temporary’ folders in NIST database verified
by measurement (sound velocity in superheated phase)
Summary of thermal management meeting
CO2 Status report A. Colijn, NIKHEF
• CO2: Why?
• CO2: Cooling system for LHCb vertex detector
• CO2: Research plans at NIKHEF
Summary of thermal management meeting
ΔH(-35C) = 280 kJ/kg
Enthalpy [kJ/kg]
Pre
ssur
e [b
ar]
P = 12 bar
liquid
2-phase gas
CO2 properties: p-H diagram
Attention: Tcrit ~30°C
Summary of thermal management meeting
LHC-b ‘VELO’ vertex tracker CO2 cooling system: (NIKHEF)
2-phase
gas
R404a chiller
22
33
6677
11
88
44
2-phase2-phase
liquid liquid liquid
2-phase
Con
den
ser Evaporators
Concentric tubePump
Rest
rict
ion
AccumulatorCooling plant area
Transfer lines(~50m) VELO area
55
liquid
Fully assembled under testingInstalled nowUnder
construction
VELO areaCooling plant area
detectors
Summary of thermal management meeting
VTCS cooling cycle
CO2 Cooling at NIKHEF 8 May 2006 Bart Verlaat 13
VTCS CO2 cycle in the Pressure – Enthalpy diagram
-450 -400 -350 -300 -250 -200 -1505x102
103
104
2x104
h [kJ/kg]
P [k
Pa]
-40°C
-30°C
-20°C
-10°C
0°C
10°C
0.2 0.4 0.6
Tertiary VTCS in P-H diagram
1
23
4
5
67
Accumulator pressure = detector temperature
Transf er tube heat exchange brings evaporator pre expansion per defi nition right above saturation
Saturation line
Capillary expansion brings evaporator blocks in saturation
Detector load
Summary of thermal management meeting
LHCb: Mechanical constructionAccumulator
CO2 pumps
Heat exchanger
Automatic valves
FRONT
BACK
Summary of thermal management meeting
NIKHEF & CO2: Cooling plant
Test setupCompact CO2 cooling plant
Primary CO2 cooler
Acc
umul
ator
Con
dens
orPump
Heat exchanger
Secondary CO2 circulation circuit
Compressor (with oil)
cond
enso
r
Detector
Summary of thermal management meeting
Summary of thermal management meeting
Summary of thermal management meeting
USA15:USA15: C C33FF8 8 compressorscompressors
Back-pressure regulator rack: setting of Back-pressure regulator rack: setting of evaporation pressure (temperature) evaporation pressure (temperature) (64 / 324 circuits)(64 / 324 circuits)
Summary of thermal management meeting
Summary of thermal management meeting
Infrastructure at CPPM
Summary of thermal management meeting
Summary of thermal management meeting
GUI in PVSS II
Finite state machine in PVSS to send fluid through pixel ladder by sequencing pneumatic valves
Summary of thermal management meeting
GUI in PVSS II
Machine a état finie pour envoyer fluide vers l’échelleséquencing des vannes pneumatiques
Part of a run of 1000 heat/cool cycles (Accelerated Thermal Stress Test
of thermal interfaces in a pixel stave)
Summary of thermal management meeting
New compressor at CPPM : capacity = 4kW
PID controllers
Condensor
Aspirationbuffer
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