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

2

• 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 ?

3

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.

5

Foams characterization and prototyping done at LBNL

6

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

7

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

9

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

14

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


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


-30

-25

-20

-15

-10


T(o C

)

0.63

0.50

0.38

0.25

0

W/cm2


-35

-30

-25

-20

-15


T(o C

)

0.63

0.50

0.38

0.25

W/cm2


-50

-45

-40

-35

-30

-25

-20


T(o C

)0.63

0.50

0.38

0.25

W/cm2


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












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 ?

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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 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


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

R&D on CO2 cooling at SLAC - CERN Documents/Presentations...M.Oriunno, SLAC CERN, Feb.10, 2010 2 •...

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Transcript of R&D on CO2 cooling at SLAC - CERN Documents/Presentations...M.Oriunno, SLAC CERN, Feb.10, 2010 2 •...