ann van lysebetten

1

Ann Van Lysebetten

CO2 cooling experience in the

LHCb Vertex Locator

Vertex 2007 Lake Placid 24/09/2007

OutlineOutline

Ann Van Lysebetten Vertex2007, Lake Placid

VeLo IntroductionVELO CO2 Cooling systemEvaporator Lab performanceCooling plant operationMajor challengesFinal Cooling plant performance Module Thermal performanceConclusions

2

3

VErtex LOcatorVErtex LOcator

Silicon sensors

Vacuum vessel

rf-box

rectangular bellows

exit window

wake field suppressor

kaptons


4

VELO detector halfVELO detector half


kaptons

21 + 2 silicon sensors

cooling pipes + cookies

manifold

Beam (7mm)

VELO cooling requirementsVELO cooling requirements

Ann Van Lysebetten Vertex2007, Lake Placid 5

Temperature silicon sensors ~-5ºC at all times cooling temperature of -25ºC

VELO Thermal Control System

based on CO2 Evaporator

Harsh non-uniform radiation environment

avoid thermal runaway in silicon

hold reverse annealing

radiation hard refrigerant

Vacuum

Direct contact between cooling and module

No connections but failsafe orbital welds

In LHCb acceptance low mass system

No mechanical stress on the module

Cooling capacity up to 800W/half

The CO2 cooling principleThe CO2 cooling principle

No local evaporator control,

evaporator is passive in detector

Con

dens

er

PumpHeat exchanger

Flooded evaporator

Restriction

2-Phase Accumulator

He

at

in

He

at

in

He

at

ou

t

He

at

ou

t

prim. System H2O 10C

Sec. System (freon)

Tert. System (CO2)

Detector waste heat

Tertiary System: two-phase accumulator controlled system

6Ann Van Lysebetten Vertex2007, Lake Placid


-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

Transfer tube heat exchange brings evaporator pre expansion per definition right above saturation

Saturation line

Capillary expansion brings evaporator blocks in saturation

Detector load

The CO2 cooling cycleThe CO2 cooling cycle

Con

dens

er

PumpHeat exchanger

Flooded evaporator

Restriction

2-Phase Accumulator

Hea

t in

Hea

t in

Hea

t out

Hea

t out

1 2 34

5

6

7

The implementationThe implementation

Vertex2007, Lake Placid

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

Evaporator :• VTCS temperature ≈ -25ºC• Total Evaporator load ≈ 0-1600 Watt• Completely passive

Accessible and a friendly environment

Inaccessible and a hostile environment

R507aChiller

6

2-phase

Evaporator

5

4Cooling plant:• Sub cooled liquid CO2 pumping

• 12.5 kg CO2 per half

• CO2 condensing to a R507a chiller• CO2 loop pressure control using a 2-

phase accumulator • Redundancy with spare pump and

backup chiller• Control of the system by Siemens PLC

Ann Van Lysebetten 8

9

The cooling plantThe cooling plant

CO2unit freon chiller9Ann Van Lysebetten Vertex2007, Lake Placid

3 CO2 pumps

Accumulators

Heat exchanger

2 Compressors(Air and water chiller)

10

Accumulator

CO2 pumpsCompressors


valves

Installation at CERNInstallation at CERN

July- August 2007

CO2 Unit

Freon Unit

Controls PLC


12

23 parallel evaporator stations

+ Al cast cooling blocks

vacuum feed through

capillariesand return

hose

liquid inletvapor outlet

PT100 cablescapillaries

inner=0.5mm

The EvaporatorThe Evaporator



23 parallel evaporator stations

+ Al cast cooling blocks

vacuum feed through

capillariesand return

hose

liquid inlet

vapor outlet

PT100 cablescapillaries

inner=0.5mm

The EvaporatorThe Evaporator

14

0

1

2

3

4

5

6

7

8

9

10

-26

-25

-24

-23

-22

-21

-20

12:43:12 12:57:36 13:12:00 13:26:24 13:40:48 13:55:12 14:09:36Time

HX16 TT122 HX25 TT127 Tevap Out (ºC) Massf low (g/s)

Mass flowMod25Mod16evaporator

tota

l mas

s flo

w [

g/s]

tem

pera

ture

[o C

]

annular gas+liquid flow

nominal flow = 12 g/sdry out

Evaporator Lab PerformanceEvaporator Lab Performance


heat load 1.4x nominal

From room temperature to set-point of-25 ºC

Ann Van LysebettenStart-up in ~2 hours

A B C D

-40.00

-20.00

0.00

20.00

40.00

60.00

80.00

100.00

9:36:00 AM 10:48:00 AM 12:00:00 PM 1:12:00 PM 2:24:00 PM

Time (hh:mm:ss)

Te

mp

era

ture

('C

), P

re

ss

ure

(B

ar),

Le

ve

l (%

)

-1500.00

-1000.00

-500.00

0.00

500.00

1000.00

1500.00

Po

we

r (

Wa

tt)

Pump pressure (Bar)

Accumulator pressure (Bar)

Pumped liquid (ºC)

Evaporator (ºC)

Transfer return (ºC)

Accu heating/cooling (W)

Accu level (%)

time

Tem

p (C

), P

ress

ure

(bar

), L

evel

(%

)50 100 150 200 250 300 350 4005x100

101

102

2x102

h [kJ/kg]

P [bar

]

-40°C

-20°C

0°C

20°C

40°C

0.2 0.4 0.6 0.8

VTCS start-up and operating cycles

1

3,5

810,13

1

3 5

8

9,10,13

1

35

8

9,10131

3 5

8

9 10 13

CB

D E

A

50 100 150 200 250 300 350 4005x100

101

102

2x102

h [kJ/kg]

P [bar

]

-40°C

-20°C

0°C

20°C

40°C

0.2 0.4 0.6 0.8

VTCS start-up and operating cycles

1

3,5

810,13

1

3 5

8

9,10,13

1

35

8

9,10131

3 5

8

9 10 13

CB

D E

A

Operation: start-upOperation: start-up

15

Ann Van Lysebetten

Major ChallengesMajor Challenges

16

Hardware concerns

Pumps

• problems for cold start-up sphere valve secured by a spring

• pump-membrane failure as result of vacuuming pump filling now done by flushing.

• pump discharge burst discs replaced by spring relieves

Heat exchanger

• from food industry (no mixing between coolants) + reinforced to withstand 200bar

Safety Procedures

Accu working pressure 130bar, V =14l European directive for high pressure vessels CE certification

PLC control loops

Accu control see next slidesVertex2007, Lake Placid

VTCS Accumulator ControlVTCS Accumulator Control

Accumulator Heater Performance

0.0

50.0

100.0

150.0

200.0

250.0

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00

Accumulator Pressure (Bar)

Ther

mal

Res

ista

nce

(mK

/W)

-100.00

-50.00

0.00

50.00

100.00

150.00

Hea

ter

Tem

pera

ture

Gra

dien

t ('C

)

Resistance (mK/W)

dT heater (ºC)

1000 W750 W

500 W

400 W

250 W

100 W

Resistance @ 1000, 750, 500, 400 & 250 W

Resistance @ 100 W

-40

-20

0

20

40

60

80

100

0:00 0:05 0:10 0:15 0:20 0:25 0:30 0:35 0:40 0:45

2PACL Start-up

Heater power (%)

Accu Level (%)

Heater temp. (ºC)

Liquid temp. (ºC)

Pump inlet (ºC)

Accumulator Pressure (Bar)

Pump head (Bar)

Decrease heater power near critical point to prevent dry-out

Thermo siphon heater for pressure increase(Evaporation)

Cooling spiral for pressure decrease(Condensation)

Accumulator Properties:

• Volume 14.2 liter (Loop 9 Liter)• Heater capacity 1kW• Cooling capacity 1 kW


Accumulator pressure (bar)

The

rmal

Res

ista

nce

(mK

/W)

VTCS Accumulator ControlVTCS Accumulator Control


-50

-25

0

25

50

75

0:00 0:15 0:30 0:45 1:00 1:15 1:30 1:45 2:00 2:15 2:30 2:45 3:00

Evaporator pressure (Bar)

Condenser Inlet (ºC)

Pump inlet (ºC)

Evaporator liquid in (ºC)

Evaporative temp. (ºC)

Accu PID control loop not adequate temperature oscillations of a few degrees

Needed tuning of PID control loop to solve problem

Te

mp

era

ture

(C

)VTCS Evaporator performanceVTCS Evaporator performanceStability and response to heat-load changes

-40.00

-38.00

-36.00

-34.00

-32.00

-30.00

-28.00

-26.00

-24.00

-22.00

-20.00

1:40:48 PM 1:48:00 PM 1:55:12 PM 2:02:24 PM 2:09:36 PM 2:16:48 PM 2:24:00 PM

Time (hh:mm:ss)

Tem

per

atu

re (

'C)

-1000.00

-500.00

0.00

500.00

1000.00

1500.00

Po

wer

(W

att)

, Lev

el (

‰)

VTCS_TL_PT102.P TL_PT102 Accu Pressure

VTCS_TL_PT102.P Tsat(TL_PT102)

VTCS_TL_PT104.P TL_PT104 Pump HeadPressure

VTCS_TL_TT045.T TL_TT045 Evaporator

VTCS_TL_TT112.T TL_TT112 CO2 Pump InletTemperature

VTCS_TL_HT105.Power TL_HT105 AccuHeater

VTCS_TL_LT101.Level TL_LT101 Level

VTCS_TL_TT125.T TL_Detector heater

Evaporator Temp (ºC)

Accu Temp ≈ Set-point (ºC)

Detector Power (Watt)

600 Watt

Accu level (‰)

Accu Cooling Power (Watt)

Pumped Liquid Temp (ºC)


Po

we

r (W

att

)

19

Temperatures stable without

pressure change

@Setpoint =-25ºC:Accumulator temp: -24.8ºC Evaporator temp(No Load): -23.4ºCEvaporator temp(600 W Load):-23.0ºCStabilization time from 0 to 600 Watt: ca. 7minTemperature stability: <0.25ºC


Module CoolingModule Cooling

Cooling system at-25 oC

ModuleUnpowered

ModulePowered

Total Chip Power : ~19W

2 NTCs to monitor temperature on hybrid

NTC0

NTC1


Module Cooling & PerformanceModule Cooling & PerformanceRight/C half Left/A half

T(Setpoint – NTC1)

Cooling system to silicon

Measurement conditions not exactly as! final system (vacuum, not all modules cooled simultaneously, …)

Small variations in power consumption, modules assembly, evaporator stations variations in T

T(Cool. Cookie-NTC0)

Transfer cool-module

T(NTC0-NTC1)

Module performance

setpoint-cool. Cookie)

<T silicon> with setpoint of -25C: <T silicon> with setpoint of -25C:

(-4.2±1.4 ) C (-5.2±1.5) C

Min. -7.2 C Max. -1.0 C Min. -8.4 C Max. -2.1 C

ConclusionsConclusions


All stringent requirements met Setpoint temperatures go down to ~ -35C System proves stable operation:

without loads/with loads up to 800W Module thermal performance + CO2 cooling at -25 C

All modules at all times below 0C Low mass system without mechanical stress on moduleRedundancy built in

VELO CO2 cooling system is installed and commissioned PLC control successful

all routines implemented 1 button start/stop for main system

Looking forward to enter the final

commissioning phase with the VELO installed!

Back Up SlidesBack Up Slides


24

The cooling plant: COThe cooling plant: CO2 2 unitunit

CO2-part

243 CO2 pumps


Accumulator

Heat exchanger


The cooling plant: FreonThe cooling plant: Freon unitunit

2 Compressors(Air and water chiller)

26

VELO detector halfVELO detector half


kaptons

23 + 2 silicon sensors

cooling pipes + cookies

manifold

Beam (7mm)

Main chiller performance– Dynamic range of main chiller works properly. – Full operational range (0 to 1800 Watt) possible in

evaporator range (-25ºC to -30ºC)– Isolation needs improvement around injection valves– CO2 condensers/ Freon evaporator works beyond

expectation(Hardly no dT between Freon and CO2 )

Back-up chiller performance– Able to maintain an un-powered CO2 evaporator at -

10ºC

Stand-alone test results of the VTCS cooling

plant (No external evaporator, cooling over by-pass)

Transfer line OperationTransfer line Operation(Internal heat exchanger)

-50

-25

0

25

50

75

0:00 0:15 0:30 0:45 1:00 1:15 1:30 1:45 2:00 2:15 2:30 2:45 3:00

[10] Evaporator pressure (Bar)

[13] Condenser Inlet (ºC)

[1] Pump inlet (ºC)

2-phase

gas

R507a chiller

1

2-phase

2-phase

liquid

2-phase

Condense

r

Evapora

tor

Concentric tube

Pump

Rest

rict

ion

Accumulator

liquid

2

3 4

10

9

8765

11

1214

13

2-phase

gas

Transfer lines(Ca. 50m)Cooling plant area VELO area Inside VELO

Heater

By-p

ass

2-phase

gas

R507a chiller

11

2-phase

2-phase

liquid

2-phase

Condense

r

Evapora

tor

Concentric tube

Pump

Rest

rict

ion

Accumulator

liquid

22

33 44

1010

99

88776655

1111

12121414

1313

2-phase

gas

Transfer lines(Ca. 50m)Cooling plant area VELO area Inside VELO

Heater

By-p

ass

Acc

umul

ator

se

t-po

int

[5] Evaporator liquid in (ºC)

A B C

B

C

Transfer line temperature profile

A: Condenser and evaporator single phase

B: Evaporator 2-phase, condenser single phase

C: Both evaporator and Condenser 2- phase

[14] Accumulator pressure (Bar)

[10] Evaporative temp. (ºC)

A

Eva

pora

tor

side

Coo

ling

pla

nt s

ide


ann van lysebetten

Documents

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