LHCb VELO Meeting
LHCb VELO Cooling System
Bart Verlaat (NIKHEF)
25 February 2003
LHCb VELO Cooling System
Verification of the current design
(As described in LHCb note 2001-0XX/VELO, July 02,2001)
2001 status overview
Primary cooling system (R404A/R507):
-Capacity: 2.9 kW@-35’C
E
H
G
F
C
B
A
I
D
Secondary cooling system (R744=CO2):
-Pmax: 70 bar
-Qdetector: 2.5 kilowatt
-CO2 mass flow: 17 g/s
-Tevaporation: -30’C – 0’C
- Warm transport lines.
-Adjustable restriction in liquid transport line.
-Fixed restriction before 0.9 mm tube: ca. 10 bar.
-Heat exchanger between evaporator in and outlet
after 1st restriction.
[email protected], 29 January 03
5 ‘C
F
11
50
0
r = 60
14.3
-30
14.3
436.4
0
r= 50
436.4
0
r = 40
-30
G
14.3
-13
H
14.3
20
280
220
-30
kg/m
552.2
260
552.2
240 oC
20
200
180
431.5
642.1
300
r =757.9
A
-1
.30
0
-1.4
-1.5
0
--1.6
0
-1.70
-1.80
-1.90
-2.00
-2.10
s = -2.20
.30 kJ/kg, oC
3
Pump (IA)
I
0
r = 20
790.5
14.3
kg/m
r = 150
-35
426.5
B
r = 100
r = 75
-.6
0
Pressure, Bar
0
= 70
-32.7
-13
24.33
00
sity
Den
E
Liquid heater (AB)
Entropy = -2
100
r=8
H (J/g)
-.7
0
Liquid subcooling
D
0
90
T (’C)
-.8
0
2500 Watt
r=
r=
r=
Detector power
11
00
12
00
r=
-30’C
-40
Detector evaporative
temperature
r=
50
10
r=
00
10
24.3
-.9
0
10 bar
C
70
160
Restrixction
pressure drop
B
140
70 bar
Carbon Dioxide: Pressure -AEnthalpy Diagram70
-1
.0
0
Transport line
pressure
P (Bar)
120
1862 Watt
Point
-1.
10
Total heater power
1,000
Design status 2001
100
396 Watt
-1.
20
Gas heater
80
1466 Watt
60
Liquid heater
Secondary cooling system cycle in the P-h diagram (1).
40
0.66 l/min
20
Volume flow
t = 0 oC
12.15 g/s
-20
Mass flow
Heat exchanger: HFG=HCD
r = 50
-.50
r = 35
Melting Line
D
0
-.4
G
F
I
H
r = 25
Density
0
-.3
= 20 kg
r =1
E
0
-.2
x=0.3
x=0.4
x=0.5
x=0.6
x=0.7
x=0.8
Gas heater (GH)
x=0.9
r=
0
x=0.2
=
x=0.1
r=1
0
-.1
r=
s
10
C
200
180
160
140
120
100
80
60
40
20
0
Detector power (EF)
-20
Sublimation Line
Triple Point (5.18 bar, -56.558 oC)
Enthalpy, kJ/kg
1
300
400
500
600
700
800
900
Minimum primary cooling capacity: 4362 Watt@-35’C
[email protected], 29 January 03
Liquid heater
1021 Watt
Gas heater
0 Watt
D
0
90
-29.9
437.7
20
540
200
H (J/g)
-30
24.3
-29.4
437.6
437.6
3
00
r=8
E
180
140
160
140
120
100
80
60
40
r=
00
10
C
T (’C)
sit
Den
y
/m
0 kg
= 70 14.3
r = 60
0
-30
F
14.3
-30
G
14.3
20
H
14.3
20
r= 50
437.6
0
0
r = 40
688.1
300
r =790.5
-35
r = 150
426.5
r = 100
-.7
0
14.3
0 kg/m
790.5
r = 20
-.8
0
I
-.9
0
-1
.0
0
-1.
10
-1.
20
-1
.30
-1.4
0
--1.6
0
B
-1.5
0
C
-1.70
-2.10
-2.00
A
s = -2.20
/kg, oC
3
Entropy = -2
.30 kJ
5 ‘C
r=
50
10
-1.80
2500 Watt
r=
r=
r=
Detector power
-40
-30’C
100
11
50
r=
Liquid heater (AB)
Detector evaporative
temperature
Liquid subcooling
20
10 bar
t = 0 oC
Restrixction
pressure drop
12
00
140 bar
-20
1021 Watt
Transport line
pressure
P (Bar)
-Heat exchanger before expansion valve
A
140
Carbon Dioxide: Pressure - Enthalpy Diagram
-140 bar liquid transport
B
140
11
00
1,000
Point
1st
-1.90
Total heater power
Modified status:
260
0.54 l/min
240 oC
Volume flow
220
9.98 g/s
280
Secondary cooling system cycle in the P-h diagram (2).
Mass flow
r = 75
-.6
0
Pressure, Bar
Pump (IA)
r = 50
-.50
Heat exchanger: HFG=HAB
Melting Line
10
r = 35
0
-.4
D
F
I
r = 25
=
Density
0
-.3
G/H
20 kg
r =1
E
0
-.2
r=1
0
-.1
x=0.4
x=0.5
x=0.6
x=0.7
x=0.8
r=
0
x=0.3
x=0.9
=
x=0.2
r=
s
x=0.1
200
180
160
140
120
100
80
60
40
20
0
Detector power (EF)
-20
Sublimation Line
Triple Point (5.18 bar, -56.558 oC)
Enthalpy, kJ/kg
1
300
400
500
600
700
800
900
Minimum primary cooling capacity: 3521 Watt@-35’C
[email protected], 29 January 03
VELO Cooling overview and optimization
•
Warm transport has more impact on the design as foreseen, but is possible if:
–
–
•
The efficiency of the system can be optimized by:
–
–
–
•
•
The primary cooler capacity is increased.
The liquid transport pressure is increased (70 bar is in a very critical region)
Keeping the secondary refrigerant flow (CO2) to a minimum (See table)
Moving the heat exchanger in the liquid line from CD to AB
Increasing the liquid transport pressure (Current pump limit is 140 bar)
The evaporator flow conditions seem to be in the proper flow regime, but are more critical for dryout in when the system is optimized. (x=0.83 w.r.t. x=0.68) ( “x” is the vapor quality). Tests have to
determine the dry-out limit for the VELO evaporator flow conditions.
If the heat exchanger stays in place the cold gas can be used to cool additionally heat sources on
the VELOI. If not applied the cold gas will be heated electrically to avoid conde4nsation on the
vapor line.
Results summary
2001 Original Version
2003 Optimized version
Primary cooler capacitance
4.36 kW @ -35’C
3.52 kW @ -35’C
Pump flow
0.66 l/min
0.54 l/min
Detector vapor quality x (%)
68%
83%
Fluid state in heat
exchanger
Inlet
Vapor/Liquid
Liquid
Outlet
Vapor/Gas
Vapor/Gas
[email protected], 29 January 03
VELO thermal requirements:
Silicon Wafers thermal requirements:
Operating temperature range: -10 ‘C/ 0 ‘C LHCb2001-070/VELO
Survival temperature range: xx
Temperature stability: xx
Maximum accepted gradient between sensors: xx
Dissipated heat: 0.03W-0.17W (0.3 W max). LHCb2001-070/VELO
Beetle chip thermal requirements:
Operating temperature range: xx
Survival temperature range: xx
Dissipated heat: 2500 Watt total. LHCb2001-0XX/VELO, July 02,2001
External electronics requirements:
External electronics dissipation: 1500 Watt (MVB)
Other heat sources:
Corrugated foil heat dissipation: 2.2 Watt/Foil (FK)
Any other possible heat source???
Other temperature requirements:
Module base operational temperature: Assembly room temperature (ca. 20’C) (MD)
Corrugated foil: Lower than environment to get tension instead of compression. (HBR)
Any other temperature requirements???
LHCb environment temperature: 20'C?
Any large amount of dissipation near the Vertex?
[email protected], 18 February 03
Future activities
(Very preliminary)
•
The shown enthalpy cycles will be verified with a low power test set-up, using the
existing AMS-TTCS CO2 system at NIKHEF.
–
–
–
Enthalpy measurements
Evaporator pressure drop measurements
Heat transfer measurements (Dry-out determination)
•
Based on the test results a baseline design concept will be chosen.
•
A BBM (Bread Board Model) will be built conform this baseline.