Download Y.U. Jeggels

Thermal management and temperature
control of a containerised rapid
deployment radar system
Y.U. Jeggels
Supervisor: R.T. Dobson
Department of Mechanical Engineering
University of Stellenbosch, Private Bag X1
7602, South Africa
Tel: +27 21 8084268
Email: [email protected]
Fax: +27 21 8084958
Overview
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•
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Slide 2
Thermal management design process (TMDP) for
electronic equipment
Thermal management problem
Conclusion
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Thermal management design process for
electronic equipment
• Thermal management
•
•
design process (TMDP) for
electronic equipment is a
document setup for industry
Intended to form the basis of
a company’s thermal design
process
Consists of:
• TMDP methodology
• General electronic
• Thermal management
design process methodology
• Belady (2001)
equipment design
guidelines
Slide 3
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Thermal management design process for
electronic equipment
Item
Cooling solutions
Level
of item
• ‘Support materials’ for the
methodology
• TMDP logic flow chart based on
•
Sergent and Krum’s (1998)
thermal design process flow
chart
Cooling solution level
definitions (CSLD)
1st
Component
??
2nd
PCB
??
??
??
??
6th
Unit
??
7th
Rack
??
8th
System
Energy transferred to
environment
Environment
Slide 4
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General electronic equipment design
guidelines (GEEDG)
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•
•
The ultimate goal of a system thermal design is not the
predication of the component temperatures, but rather the
reduction of thermally associated risk to the product
(Minichiello and Belady, 2002).
GEEDG has been setup to sensitise the designer to
thermal aspects electronic equipment design
Discusses
• Heat sinks (Is not a “magical object to transfer energy to other
•
•
•
Slide 5
dimension”)
Air flow
Heat pipes
Etc
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Thermal management case study
• Apply the TMDP to the ESR
•
220 ‘Kameelperd’
Solid state L-band 2D
surveillance radar system
System container
Slide 6
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System container
Air
Conditioning
Unit (ACU)
Radar
Equipment
Container
(REC)
Door
Books
‘Other’
container
System
container
Radios
Air filter
Slide 7
ACU under the
radar control
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stations
Radar equipment container (REC)
• Radar equipment container
•
is the focus of the project
Consists of the following
units:
• High power amplifier (HPA)
• Receiver front end (RFE)
• Driver amplifier (DA)
• Synthesiser (SYN)
• Digital signal processor (DSP)
• Positioner interface (PSI)
HPA
RFE
DA
SYN
DSP
PSI
Slide 8
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Thermal management problems
• Transistors in the HPA fail
• The DSP processors exceed
due to:
• Thermal cycles in normal
•
•
operating cycles
Thermal shock
Excessively high temperatures
under high system container
temperatures
• Main system container
temperature is too cold. (As
low as 8ºC measured while
18 – 24ºC is recommended
(Dul and Weerdmeester,
2001))
Slide 9
© CSIR 2006
•
•
their temperature
specifications when the
DSP’s fans are switched off
Can not apply the design
phases nor logic flow to the
existing design
However, can apply the
cooling solution level
definitions to the radar
system
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Thermal management problems
• Transistor temperatures are
• Evaluation of the flow inside
dependant on the original
HPA cooling solution
Air flow in the system
container and REC
Result:
• Analysis of the original HPA
the REC
Use CFD to evaluate the
flow inside the REC
• To increase the minimum
•
•
•
•
Slide 10
cooling design
Evaluation of the flow inside the
REC
Propose alternative HPA
cooling solution
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•
•
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pressure in the REC
Improve the flow path in the
REC
Done to increase the air flow
rate through the REC and to
decrease the DSP processor
temperatures
HPA
HPA fan
location
Simplified
HPA
RFE
Processor
heat sinks
Air flow
holes
Fan locations
DA
DSP
SYN
DSP
Removed
during
simplification
PSI
Slide 11
PSI plane
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locations
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DA RFE SYN
‘Block’ boards
Slide 12
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Evaluation of the air flow
inside the REC
HPA
• Changes to the REC are to
RFE
be evaluated against the
datum simulation
• DSP processor heat sink
•
DA
temperature
Minimum pressure
SYN
DSP heat
sinks
DSP
Y
PSI
X
Z
EMI
Slide 13
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Datum simulation
HPA
Slide 14
RFE
DA
SYN
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DSP
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PSI
PSI removed
HPA
Slide 15
RFE
DA
SYN
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DSP
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PSI
Evaluation of the air flow inside the REC
and the original HPA cooling solution
• From the CFD evaluation,
the following are
recommended changes to
the REC
• Redesign of the RFE and DA
• Removal of the PSI
• Rearranging the SYN line
•
replaceable boards
Either the removal of the
existing EMI shield or replacing
it with a new EMI shield design
• Original HPA cooling was
•
•
conduction in aluminium
plate with convection to air
Numerical model of the
original HPA cooling solution
was set up using
experimental data
65 ºC plate temperature
when the transistor are
under normal operation
conditions
Transistors
Slide 16
Air
flow
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Fins
HPA cooling
• New HPA design
• Cooling solution concepts
requirements
• Transfer 320 W
• 40 ºC or lower plate
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•
Slide 17
•
temperature required
Temperature controllable
Cooling temperature
independent of the system
container temperature
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are:
Water cooled cold plate
• QED … literature on it
• Client does not want water
•
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inside the REC
Solution does not allow for a
line replaceable design
New HPA design
• Other cooling solution
•
concepts are:
Heat pipe
• Insufficient space for sufficient
condenser area
• Bent thermosyphon
•
Was tested, but can not transfer
sufficient energy
• Closed loop thermosyphon
Slide 18
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New HPA design
• Other cooling solution
•
concepts are:
Heat pipe
• Insufficient space for sufficient
condenser area
• Bent thermosyphon
•
Was tested, but can not transfer
sufficient energy
• Closed loop thermosyphon
Slide 19
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New HPA design
• Other cooling solution
•
concepts are:
Heat pipe
• Insufficient space for sufficient
condenser area
• Bent thermosyphon
•
Was tested, but can not transfer
sufficient energy
• Closed loop
thermosyphon
Slide 20
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Single pipe thermosyphon
• Thermosyphon
•
• Gravity assisted
A heat pipe is a
thermosyphon with a wick
material inside
• Allows the transfer of heat
•
against gravity
Due to capillary action in the
wick material
Cooling
section
Adiabatic
section
Heating
section
Slide 21
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Heat
output
Vapour
flow
Liquid
flow
Heat
input
Closed loop type thermosyphon
Liquid
flow
• Closed loop thermosyphon
•
• Gravity assisted
Tested with evaporator (heat
input section) horizontal and
the condenser (heat output
section) vertical
Vapour
flow
Heat
output
Cooling
section
Heat input
Vapour
flow
Liquid
Heating section flow
Slide 22
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CSLD for the closed loop thermosyphon HPA
design
Item
Level
of item
1st
Component
5th
LRU
Cooling
solutions
Combination of
conduction in
thermal paste and
aluminium, and
thermosyphon
Conduction in
thermal paste
6th
Unit
Single or two
phase heat
transfer
8th
System
Convection to
environment
Environment
Slide 23
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Closed loop thermosyphon
• Configurations tested
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transfer rate
• A single ½” CLTS FR 1 water
Cold drawn copper tubes
Working fluid: R134a, butane
and water
Diameters (outside): ¼” (6.35
mm), ⅜” (9.5 mm,) and ½”
(12.7 mm)
Water cooled cold plate
•
Different CLTS
configurations compared by
∆Tsys temperature difference
• ∆Tsys = Th,av – Tc,av (Difference
between the average
evaporator and condenser plate
temperatures)
Slide 24
• For the required 320 W heat
© CSIR 2006
•
•
can transfer 320 W at ∆Tsys ≈ 32
ºC
Multiple CLTS can also be
used, such as 3 ¼” CLTS FR
0.75 R134a at ∆Tsys ≈ 35 ºC
Other configurations
•
½” CLTS FR 1 water with a
water cooled cold plate is the
recommended design for the
new HPA
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Conclusion
• Air flow inside the REC has
•
been evaluated and changes
recommended
Changes are also
recommended to the system
container
• Original HPA cooling solution
•
has been analysed
A HPA cooling solution
proposed
• Has a lower plate temperature
•
•
Slide 25
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than the original cooling
solution
Can be temperature controlled
Cooling temperature
independent of the system
container temperature
Thank you
Questions?
Slide 26
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References
• Minichiello, A. and Belady,
•
Slide 27
C., “Thermal design
methodology for electronic
systems”, 2002 Inter Society
Conference on Thermal
Phenomena, 2002.
Sergent, J.E. and Krum, A.,
1998, Thermal management
handbook for electronic
assemblies, McGraw-Hill,
New York
© CSIR 2006
• Belady, C., June 2001,
•
Effective thermal design for
electronic systems, HewlettPackard company,
http://www.coolingzone.com
[13 August 2005]
Dul, J. and Weerdmeester,
B., 2001, Ergonomics for
beginners: A quick reference
guide, Second edition, Taylor
and Francis, London.
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