Transcript Bez nadpisu
Progress in the Development of Evaporative Cooling Systems
for the ATLAS Inner Silicon Tracker
G. Hallewell1 and V. Vacek2
1 Centre de Physique des Particules de Marseille-(CNRS/IN2P3), Campus des Sciences de Luminy,
13288 Marseille, France
2CTU, Faculty of Mechanical Engineering, Department of Applied Physics
Technická 4, 16607 Praha 6, Czech Republic
ABSTRACT:
We report on the development of evaporative fluorocarbon cooling recirculators and their control systems for the ATLAS inner silicon tracker. The silicon substrates of the silicon pixel and
micro-strip sensors of the ATLAS inner tracker must be continuously operated at a temperature below –7°C for a ~ 10 year operational lifetime at LHC. In addition, for physics motivations, the
detector cooling system must present the minimum possible extra material.
We have developed a prototype circulator using a dry, hermetic compressor with C3F8 refrigerant, and have prototyped the remote-control analog pneumatic links for the regulation of coolant
mass flows and operating temperatures that will be necessary in the magnetic field and radiation environment around ATLAS.
All elements of the circulator and control system have been implemented in prototype form. Temperature, pressure and flow measurement and control use 150+ channels of standard ATLAS
LMB ("Local Monitor Board”) DAQ and DACs on a multi-drop CAN network administered through a BridgeView user interface. Prototype 16 channel interlock modules have been tested.
Highly satisfactory performance of the circulator under steady state, partial-load and transient conditions were seen with proportional fluid flow tuned to varying circuit power. Future
developments are outlined.
A prototype circulator (Figure 1) is centred on a hermetic, oil-less piston
compressor operating at an aspiration pressure of ~1 barabs and an output
pressure of ~10 barabs
Aspiration pressure is regulated via PID variation of the compressor motor
speed from zero to 100%, based on the sensed pressure in an input buffer
tank. A thermal simulator of 22 individually powered barrel SCT silicon strip
modules is used as a variable load in these studies. Each module is monitored
with a PT100. The thermal interlock to the module power supply is triggered
from a negative temperature coefficient (NTC) thermal sensor.
Cooling circuit log p-h diagram
Interlock Box Control System
PC
ADC: Status
0
1
2
DAC
Analog
voltages
0-10 V
ADC: Temperature
12
1
12
1
Dry compressed
air
P
P
1
PMAX = 3 barABS
E
E
PC
CAN BUS
12
CAN BUS
CAN
COUPLER
E
6
P
Analog compressed air
lines ~ 150 m
Relay
Card A
PMAX = 10 barABS
Interlock Box
1
12
M12
M11
M10
M9
M8
M7
M6
M5
M4
M3
M2
Relay
Card B
M1
1
12
DIP
Switches
7
Capillaries
M12
M11
M10
M9
M8
M7
M6
M5
M4
M3
M2
STAVE1
M1
B
A
NTC12
Electro-Pneumatic Control Schematic
NTC1
M12
M11
M10
M9
M8
M7
M6
M5
M4
M3
M2
M1
Figure 1
Special Modifications:
Two transparent tubes in
Service Plant Physical Layout
WHAT IS GOING TO BE COOLED DOWN ?
CVI2000
RELAY CARD FOR INTERLOCK BOX
Ibox status in
Chan1-Chan8 with
pull-down resistors
Logic
Voltage in
exhaust line
2 m long heater divided in
two sections
Additional temperature and
pressure sensors
3 PID controllers [for
heaters control and flow
control]
Board
Status
on/off
Reset in
Reset Out
High
Temperature
Indicator for
Chan6
Power
Supply in
Module 6
Powered
Heater Output
Channels:
Chan 8
Chan 6
Chan 7
Chan 4
Chan 5
Chan 2
Chan 3
Chan 1
Power Supply
Indicator
Typical Screen from the BridgeVIEW User Interface
Exhaust tube modification for the Cooling System set-up with Haug Compressor
2nd Heater - 210 cm long in tw o sections:1st section 150 cm long; 2nd section 50 cm long
Data Acquisition
200 cm
Temperature, pressure and flow measurements in the circulation system, and
on prototype SCT and pixel thermo-structures under test, are made using
prototypes of the standard I/O system of the ATLAS DCS (”Detector Control
System”). The industrial field-bus CAN is used to read out distributed nodes,
called LMBs ("Local Monitor Boards"), running the CANopen protocol. The
LMBs are designed to serve for the controls of all ATLAS sub-detectors, and
will contain different analog and digital I/O functions.
200 cm
2nd Transparent tube
1st Transparent tube
1st Heater - 50 cm long
INNER DETECTOR [ID]
PIXEL AND SCT PART of
the ID below –7C
Conclusions:
CVI 2000
COLD BOX
•Following on from our measurements on thermal prototypes
of ATLAS SCT and Pixel Detector elements, we have developed
the system with reliable control features for a multiple parallel
channel C3F8 evaporative cooling recirculator.
Typical results from measurements
Geneva University SCT stave prototype measurements
Temperature profile along the SCT stave at nominal power dissipation
Map of NTC and Pt100 Sensors
Nominal power [7.5W (Hyb.)+2W (Si)] per module; LONG AND STABLE RUN
Geneva SCT stave, nominal power
Temperature controlled box
20
Module temperature
Tube temperature
15
Ghost SCT staves
Spec's
Linear (Spec's)
Linear (Tube temperature)
o
Temperature [ C]
10
Two SCT fully instrumented
staves
1F,3 Mod2St2L
-20
Stave 2
M12
M11
M10
1F,15 Mod11St2H
1F,16 Mod12St1L
1F,12 Mod10St1L
M7
M8
M9
1F,11 Mod9St2H
M6
1F,E Mod8St1L
M4
M5
1F,D Mod7St2H
1F,9 Mod5St2H
1F,A Mod6St1L
M3
1F,6 Mod4St1L
M1
M2
1F,5 Mod3St2H
1F,1 Mod1St2H
Pt100
sensors
-25
NCT
sensors
0
1F,2 Mod2St1L
M11
M10
1F,14 Mod11St1H
M9
1F,10 Mod9St1H
M8
M7
1F,C Mod7St1H
M6
M5
1F,8 Mod5St1H
FLOW
©2001 V. Vacek
M4
M3
1F,4 Mod3St1H
M2
M1
1F,0 Mod1St1H
CVI2000
10
15
20
Position No. of the sensors along the stave
25
pevap= 1.55 barabs ; pstave=0.38 bar; Refrigerant flow = 2.66 g/s;
pcondenser = 8.3 barg; tcondenser = 31 C; pbuffer = 1220 tor
Sub-cooling:
tset= -10C ; tfluid= -9.8C ; flow = 58 dm3/hour
Run conditions:
Stave 1
M12
5
-24.0
1F,7 Mod4St2L
No power on two
modules
-23.5
1F,B Mod6St2L
-10
-20.0
1F,F Mod8St2L
-5
-19.3
Outlet
1F,13 Mod10St2L
0
-15
FLOW
1F,17 Mod12St2L
5
•Power interlocks and proportional control of refrigerant flow
have been successfully demonstrated. During transient
conditions, powered modules remained stable in temperature,
while the exhaust tubing of the evaporative cooling circuits
could be maintained a significant margin above the C3F8
evaporation temperature (and at a higher temperature than in
a mono-phase liquid cooling system), simplifying the insulation
in the final ATLAS installation.
30
•Irradiation studies have indicated that generic saturated
fluoro-carbon refrigerants of the form (CnF(2n+2)) are suited to
the ATLAS application provided hydrogen donor impurities
are kept at a low level using standard purification procedures.
This is believed to be acceptable in a closed circuit system.