ann van lysebetten
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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
Ann Van Lysebetten Vertex2007, Lake Placid
4
VELO detector halfVELO detector half
Ann Van Lysebetten Vertex2007, Lake Placid
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
7Ann 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
Ann Van Lysebetten Vertex2007, Lake Placid
valves
Installation at CERNInstallation at CERN
July- August 2007
CO2 Unit
Freon Unit
Controls PLC
Ann Van Lysebetten Vertex2007, Lake Placid 11
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
Ann Van Lysebetten Vertex2007, Lake Placid
13Ann Van Lysebetten Vertex2007, Lake Placid
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
Ann Van Lysebetten Vertex2007, Lake Placid
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
Ann Van Lysebetten Vertex2007, Lake Placid 17
Accumulator pressure (bar)
The
rmal
Res
ista
nce
(mK
/W)
VTCS Accumulator ControlVTCS Accumulator Control
Ann Van Lysebetten Vertex2007, Lake Placid 18
-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)
Ann Van Lysebetten Vertex2007, Lake Placid
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
20Ann Van Lysebetten Vertex2007, Lake Placid
Module CoolingModule Cooling
Cooling system at-25 oC
ModuleUnpowered
ModulePowered
Total Chip Power : ~19W
2 NTCs to monitor temperature on hybrid
NTC0
NTC1
21Ann Van Lysebetten Vertex2007, Lake Placid
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
Ann Van Lysebetten Vertex2007, Lake Placid 22
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
Ann Van Lysebetten Vertex2007, Lake Placid
24
The cooling plant: COThe cooling plant: CO2 2 unitunit
CO2-part
243 CO2 pumps
Ann Van Lysebetten Vertex2007, Lake Placid
Accumulator
Heat exchanger
25Ann Van Lysebetten Vertex2007, Lake Placid
The cooling plant: FreonThe cooling plant: Freon unitunit
2 Compressors(Air and water chiller)
26
VELO detector halfVELO detector half
Ann Van Lysebetten Vertex2007, Lake Placid
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 Vertex2007, Lake Placid
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