The future of CO2 cooling in particle physics - Www Group Slac ...

verlaat@nikhef.nl 

bverlaat@nikhef.nl 


Evaporative CO 2 cooling for thermal 

control of scientific equipments 

SLAC Advanced Instrumentation Seminars 

March 28, 2012, 1:30 PM, Kavli 3rd floor 

Bart Verlaat 

(Nikhef/CERN) 

1


CO 2 Cooling Seminar 

• Introduction to 2phase cooling and fluid 

trade-off 

• CO 2 cooling modeling 

• Introduction to the 2PACL CO 2 circulation 

method. 

• CO 2 cooling in the AMS-Experiment. 

• CO 2 cooling in the LHCb Velo Detector 

• Ongoing projects. 

• Conclusions 

2


Temperature (°C) 

Pressure (Bar) 

90 

60 

30 

0 

-30 

What happens inside a cooling tube? 

Heating a flow from liquid to gas 

Liquid 

Liquid 

Superheating 

Enthalpy (J/kg) 

Low ΔT 

2-phase 

Target flow condition 

Isotherm 

Sub cooled liquid 2-phase liquid / vapor 

Dry-out zone 

Gas 

Increasing ΔT 

(Dry-out) 

3 

Super heated vapor


Cooling efficiently scientific 

equipment. 

• What do we expect in general from a 2phase flow 

in scientific equipment? 

– Inside the equipment (Evaporator): 

• Small additional cooling hardware (small diameter tubing) 

• Large heat removal capacity 

• Low temperature gradients 

– Low gradient from tube wall to fluid 

– Low gradient over tube length (Isothermal) 

– Outside the equipment (Circulation system) 

• Stable temperature 

• Control over fluid condition in side evaporator 

• Which fluid is most suitable? 

4

Temperature 


Temperature profiles 

• To compare different fluids it must be understood which mechanism 

contributes to the thermal performance. 

ΔT(ΔP) 

(Reduced 

diameter) 

ΔT(ΔP) 

Tube length 

ΔT(HTC) 

(Reduced 

diameter) 

ΔT(HTC) 

ΔT(ΔP+HTC) 

(Reduced 

diameter) 

ΔT(ΔP+HTC) 

• For efficient heat transfer: ΔT(ΔP+HTC) as small as possible 

• For isothermal heat transfer: ΔT(ΔP) as small as possible 

• As in general small cooling tubes are preferred, so lets introduce a new 

property to distinguish the heat transfer relative to the needed volume 

Overall Volumetric Heat 

Q 

V tube*ΔT(ΔP+HTC)) 

Isothermal Volumetric Heat 

Transfer Conduction (W/m3K): Transfer Conduction (W/m 3 K): V tube*ΔT(ΔP)) 

Q 

5

verlaat@nikhef.nl Fluid 

• Fluid trade-off regarding 

temperature gradients, for 

simplicity: 

– Pressure drop: Friedel 

correlation 

– Heat transfer gradients: 

Kandlikar correlation. 

Temperature 

ΔT(ΔP) 

(Reduced 

diameter) 

ΔT(ΔP) 

Tube length 

Trade-off (1) 

CO 2 

Heat Transfer 

dT(HTC) 

(Dashed lines) 

ΔT(HTC) 

(Reduced 

diameter) 

Heat transfer gradients (°C) 

ΔT(HTC) 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 

Heat transfer temperature gradients 

L=1 m, Q=100 W, T=-20 °C, VQ=0.5 

Total dT(dP+HTC) 

(Thick lines) 

Pressure drop 

dT(dP) 

CO2 (19.7 bar) 

Ethane (14.2 bar) 

R116 (10.5 bar) 

Propane (2.4 bar) 

R218 (2 bar) 

Ammonia (1.9 bar) 

R134a (1.3 bar) 

0 

0 1 2 3 4 5 6 7 8 9 10 

Tube diameter (mm) 

ΔT(ΔP+HTC) 

(Reduced 

diameter) 

ΔT(ΔP+HTC) 

6

Volumetric heat transfer conduction (W/mm 3 K) 

0.035 

0.03 

0.025 

0.02 

0.015 

0.01 

0.005 


Overall volumetric heat transfer conduction 

L=1 m, Q=500 W, T=-20 °C, VQ=0.5 

CO 2 

Overall 

0 

0 1 2 3 4 5 6 7 8 9 10 


Fluid Trade-off (2) 



R116 (10.5 bar) 


R218 (2 bar) 


R134a (1.3 bar) 

Volumetric heat transfer conduction (W/mm 3 K) 

7 

6 

5 

4 

3 

2 

1 

Isothermal volumetric heat transfer conduction 

L=1 m, Q=500 W, T=-20 °C, VQ=0.5 

Isothermal 

CO 2 



R116 (10.5 bar) 


R218 (2 bar) 


R134a (1.3 bar) 

0 

0 1 2 3 4 5 6 7 8 9 10 


• Translating the temperature gradients to the volumetric heat transfer 

conductance 

– Clearly visible: CO 2 is a winner in both overall and isothermal. 

– Another interesting phenomena: The higher the pressure the more 

efficient. Is this maybe the simple answer to the perfect fluid? 

7


Is high pressure the answer to 

an efficient cooling fluid? 

• In fact it is, the higher the pressure: 

– The more the vapor stays compressed 

– The smaller the needed volume 

– But as well: lower gas speeds mean lower pressure 

drop. 

• Other properties are also important: 

– High latent heat (=less flow) 

– Low viscosity (=low pressure drop) 

– CO 2 is favorable for both properties. 

• And on top of that pressure drop is less significant 

at high pressures as it doesn’t effect the boiling 

pressure as it would do at low pressure fluids. 

8


CO 2 a perfect cooling fluid 

for scientific use 

• As shown, CO 2 is a really good candidate cooling fluid 

if the following properties are required (In general for 

scientific and high-tech equipment): 

– Low mass and low volume cooling pipes 

– Isothermal behavior 

– High heat removal capacity 

• The stability in time is a merit of the attached cooling 

plant, here fore the 2PACL principle was invented for 

particle detector cooling. 

– However high pressure fluids are less sensitive to 

pressure changes, so in fact they are as well beneficial for 

stable temperature systems. 

9

verlaat@nikhef.nl CO 

2 heat transfer and 

pressure drop modeling 

• Nowadays good prediction models of CO 2 are 

available. Especially the models of J. Thome from 

EPFL Lausanne (Switzerland) 

– See SLAC’s Advanced Instrumentation Seminar talk by 

J.Thome @ 9 feb 2011 

• Models are flow pattern based and are reasonably well 

predicting the flow conditions and the related heat 

transfer and pressure drop. 

• The Thome models are successfully used to predict 

the complex thermal behavior of particle detector 

cooling circuits. 

• A simulation program called CoBra is developed to 

analyze full detector cooling branches. 

10


Experimental heat transfer 

data (measured at SLAC) 

Interesting research on 

heat transfer is done at 

SLAC in a joint effort 

with Nikhef. 

M. Oriunno (SLAC) & 

G. Hemmink (Nikhef) 

11


P x,H x 

CoBra Calculator 

(CO2 BRAnch Calculator) 

Q x = Q applied + Q environment +Q exchanged 

dP x= f(D,Q 1,MF,VQ,P,T) or f(Cv) 

dH x= Q tot/MF or pump work 

dP pump=∑dP all 

dH condenser = ∑dH all 

P x+1 = P x - dP x 

H x+1 = H x + dH x 

T x,VQ xand properties 

derived from Refprop 

• Iterative method chopping a long line in small elements (~1mm). 

• Model can read simple configuration files giving simple tube 

geometry 

• Heat leak and internal heat exchange between elements can be 

taken into account. 

• CoBra is a very helpful tool for predicting the complex behavior of 2phase 

flow. 

12 

Q x+1 

dP x+1 

dH x+1 

P x+2,H x+2


CoBra example calculation 

2mmID x 5m tube temperature and pressure profile. MF=0.3g/s, Tsp=-30ºC, Q=90, x end =0.99 

Delta T (`C) & Delta P(Bar) 

7 

6 

5 

4 

3 

2 

1 

0 

Liquid 

5mx1.5mmID tube (4m heated), Mass flow=0.3g/s, Q=90Watt , T=-30ºC 

Slug 

Annular 

dT Tube wall (ºC) 

dT Fluid (ºC) 

dP Fluid (Bar) 

Dry-out 

1 

-1 

0 

2 

0.5 1 1.5 2 2.5 3 3.5 4 

3 

4.5 

4 

5 

Branch length (m) 

0 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 

• CoBra is able to analyze complex thermal 

behavior of CO 2 in long tubes 

350 

300 

250 

200 

150 

100 

50 

Bubbly 

Slug 

Stratified 

Annular 

Process path 

Stratified Wavy 

Dry- 

out 

Mist 

13



Internal heat exchange and 

IBL temperature and pressure profile. MF=0.8g/s, Tsp=-40ºC, Q=101.8, x end =0.5 

16 

14 

12 

10 

8 

6 

4 

2 

Stave TFoM: 13ºC*cm 2 /W 

Pixel maximum temperature: 

-24.2ºC 

Capillary 

Boiling starts 

0 

1 2 3 4 56 78 9 10 11 12 

-2 

0 5 10 15 20 25 


ambient heating 




dT Pixel Chip (ºC) 

IBL temperature and pressure profile. MF=0.8g/s, Tsp=-40ºC, Q=101.8, x end =0.41 

0 

1 2 3 4 56 78 9 10 11 12 

-2 

0 5 10 15 20 25 

Figure 7: CoBra calculation example of the IBL cooling tube. The branch has a 1mm inlet (1-4), a 1.5 mm cooling tube (4- 

8), a 2mm outlet (8-9) followed by a 3mm outlet (9-12). The dashed temperature profile is the actual sensor temperature 

taking into account the conductance of the support structure. The graph on the left has no internal heat exchange, the 

right graph takes internal heat exchange of the in and outlet tube into account. 


16 

14 

12 

10 

8 

6 

4 

2 

Stave TFoM: 13ºC*cm 2 /W 

Pixel maximum temperature: 

-24.4ºC 

No Boiling 


Boiling starts 

Figures from: DESIGN CONSIDERATIONS OF LONG LENGTH EVAPORATIVE CO2 COOLING LINES 

Bart Verlaat and Joao Noite, GL-209, 10th IIF/IIR Gustav Lorentzen Conference on Natural Working Fluids, Delft, The Netherlands 2012 




dT Pixel Chip (ºC) 

14


Comparison to test results 

m = 1.48g/s | Q total = 256.87W | P in = 26.40Bar | T in = -17.40°C | dP = 6.33Bar | dT = 10.86°C 

Temperature [°C] 

-6 

-8 

-10 

-12 

-14 

-16 

-18 

Electronics (1.8mm) 

CMS-B-PIX 

Inlet tube (1.8mm) 

CMS detector 

(1.4mm) 

Exp. Wall Temperature 

Theory Wall Temperature 

Theory CO 2 Temperature 

Theory CO 2 Pressure 

-20 

0 5 10 15 

Loop Length [m] 

20 

Outlet tube (1.8mm) 

27 

26 

25 

24 

23 

22 

21 

IBL temperature and pressure profile. MF=1.1g/s, Tsp=-26.71ºC, Q=73.5, x end =0.36 

12 

-1 

0 5 

3 4 

10 

56 78 9 

15 

10 

20 

1112 

25 


Figure 8: Temperature and pressure test results of the CMS pixel upgrade cooling branch (left) and the Atlas IBL 

cooling branch (right). Comparison with the CoBra calculator showed that the calculator is a promising tool for 

predicting the temperature and pressure gradients over long length cooling branches. 

Pressure [Bar] 


9 

8 

7 

6 

5 

4 

3 

2 

1 

0 

Inlet tube 

(1mm) 

Atlas-IBL 

Detector 

(1.5mm) 

Outlet tube (2mm) 




Outlet tube 

(3mm) 

Figures from: DESIGN CONSIDERATIONS OF LONG LENGTH EVAPORATIVE CO2 COOLING LINES 

Bart Verlaat and Joao Noite, GL-209, 10th IIF/IIR Gustav Lorentzen Conference on Natural Working Fluids, Delft, The Netherlands 2012 

15



Pressure 

90 

60 

30 

0 

-30 

bverlaat@nikhef.nl What 

Liquid Vapor 

2-phase 

Enthalpy 

What happens inside a cooling tube? 

Heating a flow from liquid to gas 

Liquid 

Liquid 

Superheating 

Enthalpy (J/kg) 

Low ΔT 

2-phase 

Target flow condition 

Sub cooled liquid 2-phase liquid / vapor 

circulation method can we use? 

Isotherm 

Dry-out zone 

Gas 

Increasing ΔT 

(Dry-out) 

3 

Super heated vapor 

Refrigeration method: 

(Atlas) 

Compressor 

Cooling plant 

BP. Regulator 

Vapor compression system 

Warm transfer 

Heater 

Detector 

If we remember slide 3, we see that proper 

cooling takes place on the liquid side, while 

compressors need gas as input. It is better to 

invent a cycle staying on the liquid side. 

=> externally cooled pump cycle.

Pressure 

bverlaat@nikhef.nl New cycle for particle detectors: 2PACL 

(The 2-Phase Accumulator Controlled Loop ) 

Liquid Vapor 

2-phase 

Enthalpy 

2PACL method: 

(LHCb) 

Compressor 

Chiller Liquid circulation 

Pumped liquid system, 

cooled externally 

Cold transfer 

• The 2PACL has the following advantages: 

– Cycle stays on the liquid side, no heat required (experiment can be cooled unpowered 

and no control heaters required) 

– Evaporator pressure=(temperature) controlled with a 2-phase vessel away from the 

experiment. No local control nor sensing needed! 

– All control hardware in a distant accessible cooling plant 

– Primary cooling can be anything, no accurate temperature control needed as long as it 

is colder than the 2PACL 2-phase temperature. 

– Inlet fluid state defined by physics => saturated liquid. 

– Large temperature range (typical from room temperature down to -40°C) 

17 

Pump 

Cooling plant Detector


Cooling plant (controls & 

actuators) in a safe and 

accessible area 

HFC Chiller 

P 7 

1 

Condenser 

2PACL application in a 

2-Phase 

Accumulator 

Heat in 

Pump 

particle detector 

Shielding wall 

Long distance 

(50-100m) 

6 

2 3 

Transfer line 

(Heat exchanger) 

5 

Only passive piping in 

detector area. Manifolds 

in accessible locations. 

Capillaries (3-4) 

for flow distribution 

Evaporator inside 

detector (4-5) 

4 

P 4-5 

18


Pressure control 

with accumulator. 

Change set-point. 

1 

7 

2-Phase Accumulator Controlled Loop 

(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 

Red dot (detector) 

on saturation line. 

Isothermal line 

3 

5 

4 

Gas 

Enthalpy 

19


Lowering saturation 

pressure 

7 

Cooling 7 

1 


(2PACL) 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 


follows saturation line. 

Enthalpy 

20



pressure 

7 


1 


(2PACL) 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 



Enthalpy 

21



pressure 

7 


1 


(2PACL) 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 



Enthalpy 

22


Set point reached 

1 

7 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 

Enthalpy 

23


Increasing saturation 

pressure 

7 

Heating 

1 

7 


(2PACL) 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 



Enthalpy 

24



pressure 7 

Heating 7 

1 


(2PACL) 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 



Enthalpy 

25



pressure 

7 


1 


(2PACL) 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 



Enthalpy 

26


Set point reached 

1 

7 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 

Enthalpy 

27


Switching on detector 

1 

7 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


evaporation starts. 


3 

5 

4 

Gas 

Enthalpy 

Heat 

28


Powering detector 


1 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4 5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 

Red line (detector) 

in evaporation. 

Enthalpy 

Heat 

29


Powering detector 


1 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

3 

2-phase 

(Evaporation) 

4 5 

6 


3 

5 

4 

Gas 



Enthalpy 

Heat 

30


Detector is on 

1 

7 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

3 

2-phase 

(Evaporation) 

4 5 

6 


3 

5 

4 

Gas 



Enthalpy 

Heat 

31


Unpowering detector 


1 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4 5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 


Evaporates. 

Enthalpy 

32


Detector power is off 

1 

7 


(2PACL) 

7 

Pump 

Pressure 

6 

2 

1 

Liquid 

2 

6 

3 

4&5 

2-phase 

(Evaporation) 


3 

5 

4 

Gas 

Enthalpy 

33


CO 2 cooling projects in 

particle physics 

• 2 CO 2 cooling systems have successfully been built for 

particle detectors 

– AMS-Tracker experiment on the International Space Station 

– LHCb-Velo experiment for the Large Hadron Collider at CERN 

• Many future CO 2 cooling systems are under design: 

– Atlas Inner B-layer @ CERN 

– CMS upgrade pixel @ CERN 

– Belle-2 @ KEKb (Japan) 

• Some are foreseen for the far future: 

– CMS upgrade tracker @ CERN 

– Atlas upgrade pixel and tracker @ CERN 

– LC-TPC for the future Linear Collider 

34


The 1 st CO 2 cooling system in Space! 

A CO 2 cooling system for Alpha Magnetic Spectrometer (AMS) 

Tracker Detector on the International Space station (ISS) 

CO 2 cooling 

radiator 

AMS in the Shuttle 

(STS-134, May 2011) 

AMS on the ISS 

35


MAGNETE 

AMS-Tracker Thermal Control System 

(AMS-TTCS) 

144 WATT 

TRD 

TOF 

TRACKER 

TOF 

RICH 

ECAL 

RADIATORE 

150 Watt detector with 

evaporator rings 

condensatori 

Primary cooling not 

needed in space as 

environment is cold. 

Direct radiation to space 

Cooling system 

component boxes 

(1 redundant) 

36


Tracker connections 

Inner plane silicon 

ladders 

AMS-Tracker with 

CO 2 cooling rings. 

Inner plane thermal 

bars and hybrids 

Inner plane 

evaporator rings 

37



10 

5 

0 

-5 

-10 

-15 

-20 

-25 

AMS TTCS Cooling 

performance in space (1) 

Evaporator partly single 

phase (gradients) 

Heat 

exchanger 

heating 

1 orbit (~1.5hour) 

Accumulator 

set point 

change 

Evaporator 

fully 2-phase 

13:00 15:00 17:00 19:00 21:00 23:00 01:00 

Pump inlet (PT02_P) 

Accumulator (PT01_P) 

Evaporator inlet (DS13-P) 

Evap 1 (SensE) 

Evap 2 (SensG) 

Evap 3 (SensF) 

Varying CO 2 liquid 

due to orbital 

fluctuations 

Time(HH:MM) 

38



20 

15 

10 

5 

0 

-5 

-10 

-15 

-20 

-25 

-30 

08/06/11 

Soyuz 

docking 



10/06/11 

12/06/11 

14/06/11 

Detector 

switched-off 

Solar Panel 

orientation 

change 

16/06/11 

18/06/11 

20/06/11 

Pump inlet (PT02_P) 

Accumulator (PT01_P) 

Evaporator inlet (DS13-P) 

Evap 1 (SensE) 

Evap 2 (SensG) 

Evap 3 (SensF) 

Magnet Average 

Date (DD/MM/YY) 

39




6 month stable at 0⁰C despite cold low beta periods 

40


VELO detector: 1.5 kW@-30°C 

(Running successfully since 2007) 

CO 2 cooling projects in LHC 

27 km 

CMS pixel: 15 kW@-20°C 

(Operational 2014) 

LHC 

Atlas IBL: 1.5 kW@-40°C 

(Operational 2013) 

Ca. 100m 

41


LHCb-Velo Thermal Control System 

(LHCb-VTCS) 

Transfer tube 

Concentric assembly 

Evaporator 

Passive tubing only Cooling Plant 

All active hardware 

Cooling capacity: 1.5 kW@-30°C 

42

verlaat@nikhef.nl VTCS 

Evaporator 

43

gas 

2-phase 

R507a 

chiller 

gas 

2-phase 


Start–up of the VTCS during October 

80 

2009 commissioning: 

8:40 - Start-up with set-point -5°C 

11:10 - Detector switched on 

60 

12:50 – Set point to -15°C 

15:30 - Set point to -25°C 

50 


18:20 - Set point to -35°C (System Limit) 

19:10 - Set point to -34°C 40 


20:00 - Detector Switched off 

Condenser 

10 

Accumulator 

Transfer lines 

Cooling plant area (Ca. 10 50m) VELO area 

9 

Pump 

1 2 

8 

Accumulator Set-point temperature Silicon temperature (°C) (°C) Pump liquid Accumulator temperature Set-point (°C) temperature Evaporator (°C) saturation Pump liquid temperature (°C) 

Temperature(°C), Level(%) 

70 

30 

20 

0 

-10 

-20 

Concentric tube 

7 

3 

Restriction 

VTCS Commissioning results: 

Start-up and operation 

ator Set-point temperature (°C) Pump liquid temperature (°C) Evaporator saturation temperature (°C) Accumulator liquid level (%) Detector heat load (W) 


4 

80 

70 

60 

50 

40 

30 

20 

10 

0 

-10 

-20 

-30 

-40 

-50 

-60 

09:00 12:00 15:00 18:00 21:00 

01-Oct-2009 

-25 

Time (hh:mm) 

5 

Silicon temperature (°C) Accumulator Set-point temperature (°C) Pump liquid temperature (°C) Evaporator saturation temperature (°C) Accumulator liquid 

Evaporator / Modules 

6 

10-Accu liquid level 

10-Accumulator set-point 

A 


-26.4286 

-27.8571 

-29.2857 

-30.7143 

-32.1429 

-33.5714 

-35 

-36.4286 

-37.8571 

-39.2857 

-40.7143 

-42.1429 

Detector power 

A-Silicon temperature 

9-Pumped liquid 

-30°C SP 

-35°C SP 

800 

700 

600 

500 

400 

300 

200 

100 

0 

-34°C SP 

44 

Heatload (W)


SP=21°C 

(Start-up) 

SP=-5°C 


Freezing 

(Solid/Liquid) 

SP=-15°C 

SP=-25°C 

SP=-30°C 

SP=-35°C 

VTCS Commissioning results: 

Start-up and operation in the PH-diagram 

T=-40°C 

9-Pump inlet 

Liquid 

Enthalpy (kJ/kg) 

2-Phase 

(Liquid/Vapor) 

T=-40°C 

T=20°C 

T=0°C 

T=-20°C 

Start-up sequence 

1. Increase pressure to 

make liquid. 

2. Pump at high pressure 

and cool down in liquid 

mode 

3. Lower pressure to 

desired set-point 

4. Power-up detector 

Switch-off detector 

Lowest possible set-point 

(liquid approaches 

saturation line) 

45


IBL detector: 

• Ø80mm x 800mm 

• 1.5 kW @ -40°C 

• 14 staves with 1 cooling pipe 

New detector with smaller beam 

pipe in space of current beam pipe 

Atlas IBL-cooling system (1) 

Carbon foam structure 

1.5mm ID titanium cooling pipe 

Pixel detector 

chips 

(70watt/stave) 

46


CMS upgrade pixel cooling 

system 

• Replacement and 

upgrade of current 

pixel detector 

• 15kW @ -20ºC 

• Very long serial lines 

with relative high heat 

flux 

F-PIX 

(Forward) 

47


KEK Belle-2 SVD and PXD 

Belle-2 PXD and SVD, 1.5 kW@-30ºC 

Common CO 2 cooling plant 

development with Atlas IBL 

Belle-II SVD 

detector 

Belle-II pixel detector 

(Rapid Prototyping heat sink) 

48

verlaat@nikhef.nl CO 

2 cooling support 

Traci Cora Marco 

• To support the CO 2 cooling projects in particle physics several test systems are under 

development: 

• Cora (CO 2 Research Apparatus) 

– Fixed test plant for CERN based research (0-2kW, +20 to -35ºC) 

• Marco (Multipurpose Apparatus for Research on CO 2 

– Fully automatic (User friendly) CO 2 test system for general use (0-2kW, +20 to -45ºC) 

– Base design for future on detector cooling plants (Atlas IBL, Belle-2) 

• Traci (Transportable Refrigeration Apparatus for CO 2 Investigation) 

– Small test system for laboratory use 

– New simplified 2PACL concept to reduce cost and complexity (0-350W, +20 to -40ºC) 

49

Experiment 

connection 

4 

5 

Experiment 

venting 

bverlaat@nikhef.nl TRACI 

Local experiment box 

condenser 

Flow regulation 

compressor 

Transportable Refrigeration Apparatus for Co 2 Investigation 

Concentric hose 

P T 

5 

Heater 

TEV 

R404a Chiller 

T 

6 

R404a evaporator/ 

CO 2 condenser 

T 

1 

TRACI layout 

CO 2 pump 

P,T 

3 

P 10 

T 

CO 2 loop 

Accumulator 

-50 

9:00 10:30 12:00 13:30 15:00 16:30 

Time (hh:mm) 

• TRACI: A simplified new concept for providing a conditioned CO 2 flow for 

cooling research. 

• 2PACL principle simplified (few functions have been integrated) 

– Integrated 2PACL (I-2PACL ) 

– Patent of I-2PACL concept filed 

• Goal: An easy to (mass) produce user friendly system 

– Operational from +25⁰C to -40 ⁰C 

– Initial cooling power up to 350 Watt (depending on minimum temperature) 


30 

20 

10 

0 

-10 

-20 

-30 

-40 

CO2 Chart liquid temperature Title (at pump) 

CO2 temperature 

Accumulator saturation temperature 

150 W on Power off 

150 W on 

50


The TRACI factory 

• Prototypes are already “mass produced” 

– 2 have been build (Atlas & LHCb) 

– 3 under construction (Atlas, CMS & Nikhef/AIDA for 

development) 

– Investigating a start-up company for real production 

51


Commercial chiller 

TRACI a modular design 

CO 2 piping in a 2Dfoambox 

User interface: 

• On/off and reset buttons 

• Error indication 

• Pressure controller 

Control: Simple 

conditioner and relay 

logic 

52

verlaat@nikhef.nl MARCO 

Multipurpose Apparatus for Research on CO 2 

• MARCO is prototype CO 2 2PACL 

system for multipurpose use. 

• User friendly 

– Automatic experiment connection 

– Automatic filling 

• Designed according to CERN 

experiment standards. 

– Baseline concept for the detectors IBL 

(CERN) and Belle-2 (KEK), common 

development with MPI-Munich. 

– PVSS-Unicos control interface 

• Low temperature design 

– 2kW@-45ºC 

– Frequency controlled 2-stage chiller 

53

verlaat@nikhef.nl MARCO 

A CO 2 2PACL build in MPI 

production 

Controls build 

at CERN-DT 

2-stage chiller for IBL 

temperatures from 

ECR-Nederland 

54


Conclusions 

• CO 2 is a very good candidate fluid for applications were limited cooling 

space is available or limited additional mass is allowed. 

• CO 2 cooling is a good candidate if high power densities are present and an 

isothermal heat sink is required 

• CO 2 cooling is widely accepted in Particle Physics community as the future 

cooling method for the inner silicon detectors. 

• The 2PACL concept has proven to be a good method for controlling 

evaporation conditions in distant set-ups 

• 2 CO 2 systems are operational in particle physics and perform well. 

• Several new systems are under development including systems for testing 

55


It’s cold here, can you 

turn the cooling off? 

Questions? 

56

The future of CO2 cooling in particle physics - Www Group Slac ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?