r&d on co2 cooling at slac - cern documents/presentations...m.oriunno, slac cern, feb.10, 2010 2...
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R&D on CO2 cooling at SLAC
M.Oriunno, SLAC
CERN, Feb.10, 2010
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• Needs CO2 cooling test facilities for the ATLAS Upgrade to test prototypes for super-LHC
• Geographical Proximity to LBNL and USC, ATLAS partnership on the West coast
• Preparing infrastructure as a possible site for assembly and testing
• Open facility to the users form all Labs and Universities pursuing cooling studies
• Cooling as a task of an R&D Collaborative Effort for the Local Supports of the future Tracker of ATLAS: Thermal management, Materials and Integrationhttps://edms.cern.ch/file/933633/1/ATLAS_RD_PixelLocalSupports_v4-1.pdf
•We consider important the sharing of knowledge with other projects pursuing similar researches, i.e. CMS PIXEL
Carbon dioxide key benefits : small tubes and low temperatures
Why SLAC is working on CO2 ?
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Step 1, Construction of a blow CO2 plant, Characterization of the boiling parameters and the heat transfer coefficientsTubes-fittings characterization under high pressure: materials, sizesFirst characterization of available prototypes
Step 2, Development of a close loop plant with larger refrigeration capacity, ~2kW Systematic tests and scanning parameter range with automated proceduresTest of larger stave/disk prototypes, eventually a system of themR&D on components : compressors , capillaries, heat exchangers, evaporators
PlansProvide advanced cooling facilities for ATLAS and to all the SLAC users pursuing similar researches .
Partnership with NIKHEF to grow faster the technology in ATLAS
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The Blow System
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SLHC Pixels Local supports R&D• All designs currently on the table use thermally conducting carbon foam +
tube (carbon, Ti or SS) coupled by loaded epoxy or loaded compliant “adhesive” and high K, high stiffness standard carbon fiber
• Different types of carbon foam (graphitic or RVC-based) on table.
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Foams characterization and prototyping done at LBNL
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Outer Pixel Staves (M. Gilchriese, LBNL)
• Two options for cable connection to modules: cable on top/bottom of stave (prototype exists) or cable (more layers) buried in stave (currently preferred for better thermal performance but prototype underway….) but modules and placement identical
Bus cable (similar concept to silicon strip staves) glued on top of mechanical stave
Cable (0.5mm thick) buried in foamDetailed layout of prototype cable underway
6At SLAC for CO2 testing…..
Preferred option. Better thermal performance, connections to support shell(s) easier
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More OuterPx Prototype Pictures(M.Gilchriese, LBNL)
7Platinum on silicon heaters
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Test with water at Room Temperature
H2O at 1 l/minSingle side heat
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1200
mm
SSteel Tube brazed on
modified Swagelok fitting
ID tube 2.2 mm, wall thickness 300um
Set up in the thermal box
10-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
2250 2750 3250 3750 4250 4750 5250 5750 6250Time
oC
No power
mf =1.4g/s
100 W
80 W
mf =1.16g/s
mf =0.64g/s
mf =0.2g/s
dry out mf =2.65g/s
mf =1.7g/s
Run with the blow system
Temp.profile @100W
Temp.profile @80W Induced dry out
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80 W
-40
-36
-32
-28
-24
-20
-16
-12
0 2 4 6 8 10 12 14
100 W
-40
-36
-32
-28
-24
-20
-16
-12
0 2 4 6 8 10 12 14
Mass flow 1.4 g/s, single face
Mass flow 1.16 g/s, single face
T=13oC
T=11oC
Tfluid
Tfluid
00.20.40.60.8
11.21.41.61.8
2
0 2 4 6 8 10 12
Average
Average
• Good agreement between H2O and CO2.• Confirms that R is independent of
– Fluid– Temperature– Power
For H20, h = 16347 W/m2KFor CO2 at 80 W, h = 6800 W/m2.K For CO2 at 100 W, h = 7400 W/m2.K
CO2 test on the Outer Pixel Stave Prototype
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Dry out studies
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
0 2 4 6 8 10 12
0.6 g/s
0.4 g/s
0.2 g/sDecreasing the mass flow we forced a dry out with a
temperature runaway at the end of the stave
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Finite Element ModelThe measurement on the stave are benchmarked with independent FEAs by SLAC and by B.Miller.
Good correlation between experiments and FEA simulation
-26.47-26.96400-3721.8CO2@80W
-22.32-22.877800-3517.6CO2@100W
28.9429.2163472016.8Water@84W
TS experiment oC
Ts FEA oC
HTC W/m2.K
T fluid oC
Heat flux kW/m2Load Case
CO2@-35C, 100W Local heat flow redistribution staggered geometry
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Blow system limitations : Pressure Waves, mass flow and temperature oscillations
ThrottlingBack-pressure
regulator
Temperature
Mass flow
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16 Platinum heaters 2 x 4 cm2
Fittings glued with epoxy on Titanium 12 Pt100 sensors, Two temperature sensors at the inlet and the outlet, Two pressure gauges at the inlet and the outlet
- Warm Test with liquid Water/Glycol - Cold Test with evaporative CO2 - Thermal FEA Simulations
T1 T2 T3 T4 T5 T6 T7 T8 T9 T12T11T10Tin Tout
PinPout
Insertable B-layer, upgrade phase 1Thermal Characterization of the 2mm Ti Stave :
640 mm
Ti grade 2 ID2mmx120um
Carbon Foam
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Temperature Profiles, Water/Glycol
0
5
10
15
20
25
30
35
0 2 4 6 8 10 12 14
Heater location
To C
Figure of Merit (o.cm2/W)Water / Glycol @ 20oC, 10oC, 0oC
mass flow avg. 20 g/sPower densities W/cm2 : 0.25, 0.38, 0.5, 0.59
8
10
12
14
16
18
20
1 2 3 4 5 6 7 8 9 10
Heater location
o .cm
2 /W
Warm test with a mono-phase Water/Glycole mixture 90/10
Chiller set points : 20oc, 10oC, 0oC
Power densities : 0.25, 0.38, 0.5, 0.63 W/cm2
Flow rate 20 g/s, Pressure drop ~2 bars
Temperature profiles Figures of merit Tsensor-Ttube-wall
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Pressure Transmitter Drucker 7500
Pt100 Temp sensor
Tee Swagelok ¼”Flow
Pressure Transmitter Drucker 7500
Pt100 Temp sensor
Tee Swagelok ¼”Flow
Cold test with evaporative CO2 (Blow system)
Blow System set points : -25oC, -30oC, -35oC, -40oC
Power densities : 0.25, 0.38, 0.5, 0.63 W/cm2
Flow rate ~1.5 g/s,
Pressure,Temperature Saturation Curve Measure Values vs. NIST database
5
7
9
11
13
15
17
19
-45 -40 -35 -30 -25 -20T (oC)
P (b
ar) NIST Database
Exp. Pressure INExp. Pressure OUT
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Pressure and Temperature Drops
-50
-45
-40
-35
-30
-25
-20
0 5 10 15
Heater location
T (o C
)
1.601.401.301.50
g/smass flowDP ~ 200 mbar, < 0.5o
Cold test with evaporative CO2 (Blow system)
Temperature Profiles and pressure drops along the stave without power
T1 T2 T3 T4 T5 T6 T7 T8 T9 T12T11T10Tin Tout
PinPout
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Evaporation Temperature -35oC, mass flow 1.5 g/s
-40
-35
-30
-25
-20
0 5 10 15Heater location
T(o C
)
0.63
0.50
0.38
0.25
0
W/cm2
Evaporation Temperature -24oC, mass flow 1.3 g/s
-30
-25
-20
-15
-10
0 5 10 15Heater location
T(o C
)
0.63
0.50
0.38
0.25
0
W/cm2
Evaporation Temperature -29oC, mass flow 1.4 g/s
-35
-30
-25
-20
-15
0 5 10 15Heater location
T(o C
)
0.63
0.50
0.38
0.25
W/cm2
Evaporation Temperature -42oC, mass flow 1.6 g/s
-50
-45
-40
-35
-30
-25
-20
0 5 10 15Heater location
T(o C
)0.63
0.50
0.38
0.25
W/cm2
Cold test with evaporative CO2 (Blow system)
Temperature Profiles for different Power densities and Evaporation temperature
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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
80
160
240
320
400
480
560
640
720
800
Flow pattern CO2, Ts=-25C,D=2mm, G=477kg/m2.s, q=18.65kW/m2
Vapor Quality
800
0
Gstrat x( )
Gwavy x( )
Gslug x( )
Gdryout x( )
Gmist x( )
G1
10 x
Flow pattern mapsIBL Stave, Ts=-25oC, heat flux = 18kW/m2 (80W)
I
Annular
Dry Out
M
Slug0 0.2 0.4 0.6 0.8
0
2 103
4 103
6 103
8 103
1 104
1.2 104
1.4 104
1.6 104
1.8 104
Heat Transfer Coefficient, CO2, Ts=-25C,D=2mm, G=477kg/m2.s, q=18.65kW/m2
Vapor Quality
18000
0
h2p x( )
10 x
h2p 0.1( ) 8.502 103
Small tubes enable stable and effective operation at the annular regime :
High Mass flux
High heat Transfer Coefficients
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Heat Transfer Coefficients measured for bare tubes 2.2 IDMass flux = 400 g/s.m2,
Heat fluxes, 9.3kW/m2(75W), 13.8kW/m2(100W), 19.7kW/m2(150W)Ts=-32oC, mf=1.47 g/s, D=2.2 mm, q = 19.7kW/m2
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Vapor Quality
HTC
(W/m
2.K
)
PredictionMeasured
Ts = -34oC, mf=1.47 g/s, D=2.2 mm, q=13. 8kW/m2
0
2000
4000
6000
8000
10000
12000
14000
16000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Vapor Quality
HTC
(W/m
2 .K)
PredictionMeasured
`
Ts=-32oC, ms=1.4 g.s, D=2.2 mm, q=9.3W/m2
0
2000
4000
6000
8000
10000
12000
14000
16000
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Vapor Quality
HTC
(W/m
2.k)
MeasuredPrediction`
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Figures of Merit (o.cm2/W)Water @ 20oC, 10oC, 0oC
Carbon dioxide @ -25oC, -30oC, -35oC, -45oC
8
10
12
14
16
18
20
0 2 4 6 8 10 12Heater Location
W/c
m2
Pd=0.50W.cm-2, Te=-40oC
Pd=0.63W.cm-2, Te=-40oC
Pd=0.50W.cm-2, Te=-29oC
Pd=0.63W.cm-2, Te=-29oC
Pd=0.50W.cm-2, Te=-24oC
Pd=0.63W.cm-2, Te=-24oC
Pd=0.50W.cm-2, Te=-35oC
Pd=0.63W.cm-2, Te=-35oC
Water 20C, 0.38 W/cm3
Water 20C, 0.63 W/cm5
Water 20C, 0.50 W/cm4
Water 20C, 0.63 W/cm5
Water 10C, 0.25 W/cm2
Water 10C, 0.38 W/cm3
Water 10C, 0.50 W/cm4
Water 10C, 0.63 W/cm5
Water 0C, 0.25 W/cm2
Water 0C, 0.38 W/cm3
Water 0C, 0.50 W/cm4
Water 0C, 0.63 W/cm5
T sensor
T tube
Q
tyPowerDensiTtubeTsensorFoM
T FluidLDhQTfluidTtube
Figures of Merit
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Temperature ProfileTube wall -> Sensor
Power Dens.= 0.25+0.4 W/cm2
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Stave Thickness (mm)
T (o C
)
FEA Results
T = 2.4oC
FEA simulation tube-foam interface, Glue 100 um, k=1 W/m.K
o
Dt
kwqT 2.22
2
Heat conduction cylindrical coordinate :
Increase k or D ?
24
Figures of Meritas by FEA simulation,
Conductive Glue 0.1mm
4
6
8
10
12
14
16
18
20
0 0.2 0.4 0.6 0.8 1 1.2 1.4
Glue Thermal cond. (W/m.K)
To C
Foam K, 135/45Foam K, 30
Zone of measured values
Experimental results and FEA Simulations
Glue Thermal Cond. nominal
Simulation
Simulation
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`
A B C
D
E
F
H
G
Cold Box insulation Foam+Dry Nitrogen
Ssteel tubes ¼”, 0.035
Capillary Tube OD1mm
Pressure Vessel 3.8 litres MAWP=70bar,MAWT=30oC
Pmin=1bar,Tmin=-50oC
Liquid CO2
Gas CO2
Ssteel tubes ¼”, 0.035
Ssteel tubes 1/2”, 0.035
Chiller 1
Chiller 2
Condenser Swep
BDW16DW
Purge
Gear Pump Gather1MX-X/12-11
500 W
CO2 Cylinder only for refilling
Chiller 1 and Chiller 2 can be merged in a single chiller
Ssteel tubes ¼”, 0.035
Ball valve
Ball Valve
Ball Valve
Swagelok Pressure Vessel304L SS/DOT-3A 1800Pn. 304L-HDF8-1GAL
Relief valve
Relief valve
Relief valve
V-15
Recirculation plant under construction
Critical items :
Accumulator (custom, NIKHEF design)
Pump (Gather MX)
Heat exchangers (Alfa Laval AXP14)
Start with commercial Freon Chiller
R&D on CO2 gas compression chiller
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IBL stave cooled at -40oC with CO2 for the first time…….
Experimental proof that Carbon Dioxide enables the IBL with Small Tubes and Low Temperatures. Excellent performances :
Small pressure drops, i.e. Uniform Temperature Profile (<1oC)
High Heat Transfer Coefficients
Thermal impedance of the conductivity of the material stack has been measured and compared with FEM
Glue layers at the Tube-Foam Interface introduce a non negligible DT
Focus on completing the recirculation plant and starting operation soon
Summary