Transcript Section 2.F - Thermal Design

GLAST LAT Project
March 24, 2003
GLAST Large Area Telescope:
Gamma-ray Large
Area Space
Telescope
Tracker Subsystem
WBS 4.1.4
2F: Thermal Design
Liz Osborne
Lockheed Martin
[email protected]
Tracker Peer Review, WBS 4.1.4 Section 2-F
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GLAST LAT Project
March 24, 2003
Agenda
•
•
•
•
Thermal Design Overview & Requirements
Interface to Grid
Thermal Model
Results
– Hot Operation, Cold Operation, Survival Minimum
• Summary & Future Work
Tracker Peer Review, WBS 4.1.4 Section 2-F
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GLAST LAT Project
March 24, 2003
Thermal Design Overview
• Requirements (check)
– Operating: -15 to +30°C
– Survival: -30 to +50°C
• 16 identical towers (25 trays each)
– 10.2W (hot) and 8.7W (cold)
per tower, located on MCM
boards
– Primary heat path is from MCM
closeouts on each tray to high
conductivity walls (K13), down
walls to Grid through
heatstraps
– High emissivity external
surfaces promote radiation
between towers and to ACD
Tracker Peer Review, WBS 4.1.4 Section 2-F
cables
3
GLAST LAT Project
March 24, 2003
Interface to Grid
• Copper straps (4 per tower) conduct Q from tower walls to the Grid
– Between walls and bottom tray
– Hot: 2.55W/strap
• RTV interface at Tracker
• Bolted (dry) at Grid
• Interface Delta T is 3°C
Tracker Walls
Not Shown
Tracker interface
Copper Straps
Grid interface
Tracker Peer Review, WBS 4.1.4 Section 2-F
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GLAST LAT Project
March 24, 2003
Thermal Model
• SINDA/TSS Model
– 82 Nodes/Tower, 1312 total
• Trays are lumped into groups
per tower
–
–
–
–
–
–
Top tray
Top 5 Standard Trays
Bottom 6 Standard trays
Heavy Trays
Standard No Converter trays
Bottom Tray
+Z
8
13
4
0
9
5
1
14
10
6
2
+Y
12
11
15
7
3
• Each Tray Group consists of 1
Tray node, 4 closeout nodes (Q
input), 8 wall nodes
• Copper strap interface to Grid
nodes
Tracker Peer Review, WBS 4.1.4 Section 2-F
+X
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GLAST LAT Project
March 24, 2003
Thermal Results – Hot (1 of 3)
• Steady State
Temperatures
– Max DT up wall is
6°C (7°C including
entire tower)
– Max Temp, +24°C
°C
Steady State Temperatures
+Z
+Y
15
0
• Located at Bay 5,
Top 5 Std Closeout
• Transient Temperatures
– Max Tracker
Transient, +24°C
W
167.4
-20.1
-147.4
0.0
Energy Balance
Tracker Dissipation
to ACD
to Grid
SUM
+X
Internal View
Tracker Peer Review, WBS 4.1.4 Section 2-F
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GLAST LAT Project
March 24, 2003
Thermal Results – Hot (2 of 3)
Tracker Bay 5 temperature over 5 Orbits
Temperature, °C
25
24
Top & Top 5 Std
23
Bott 6 Std
22
Heavy
21
20
Std N/C
19
Bottom
18
Top Tray
17
16
15
0
100
200
300
400
500
Time over 5 orbits, min
Tracker Peer Review, WBS 4.1.4 Section 2-F
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GLAST LAT Project
March 24, 2003
Thermal Results – Hot (3 of 3)
Trade: Grid/Tower Interface failure, center tower (Bay 5)
°C
• DT steady state
increase is 4.4°C
– Max Temp,
+28.4°C
Bay 4
Tracker Peer Review, WBS 4.1.4 Section 2-F
Bay 5
Bay 6
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GLAST LAT Project
March 24, 2003
Thermal Results - Cold
• Min Tracker Transient, 3°C W Energy Balance
Tracker Dissipation
to ACD
to Grid
SUM
Tracker Bay 5 Cold temperatures over 5 Orbits
10
Top & Top 5 Std
Bott 6 Std
8
Heavy
6
Temperature, C
139.5
-42.1
-97.4
0.0
Std N/C
Bottom
4
2
0
Top Tray
-2
-4
0
100
200
300
400
500
Time over 5 orbits, min
Tracker Peer Review, WBS 4.1.4 Section 2-F
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GLAST LAT Project
March 24, 2003
Thermal Results - Survival
• Minimum Tracker Survival Temperature is –24 °C
Tracker Bay 5 Survival Temperatures over 5 Orbits
0
0
50
100
150
200
250
300
350
400
450
500
Temperature, C
-5
-10
-15
-20
Top Tray
-25
Time over 5 orbits, min
Tracker Peer Review, WBS 4.1.4 Section 2-F
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GLAST LAT Project
March 24, 2003
Summary & Future Work
• Summary
– Tracker Thermal Design Presented
• Heat conducts from MCM boards to walls, down walls, through
copper strap interface to Grid
– In compliance with Requirements
Operational Temperature
Survival Temperature
Requirement
In Spec With uncertainty Design
-15/+30 C
-10/+25 C
-3 /+24 C
-30/+50 C
-25/+45 C
-24/TBD C
Margin
+7 /+1 C
+1 & heater margin/TBD C
• 4.4°C increase with complete failure at Grid/Tracker interface
for hottest tower
• Future Work
– Update thermal model as necessary
• Tracker wall material
Tracker Peer Review, WBS 4.1.4 Section 2-F
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