Harris Cold Plate Test Rig
PATRICK ARMENGOL – CPE
ERIC GUEST – CPE
ADAM BLAIR – EE
JINJIN LIN - EE
Goals and Objectives
Testing Platform
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Sensor measurements for data collection
Observe friction and temperature phenomena in steady state and pulsating airflow conditions
Analog feedback control
Data acquisition
Platform
Testing rig designed and
manufactured by ME team
Initial testing platform for
electrical components was
only 8 inches long and had
only two heaters
System Diagram
Interface Matrix
Requirements
o Create a steady state pulsating air flow
o Measure the temperature change
o Measure the mass flow
oControl the heaters and fans
o Power various components
o Collect temperature, mass flow data
Specifications
o Input air flow is sinusoidal velocity
o Pulsation frequency from 0.1 Hz to 1 Hz
o Pulsation amplitude from 0.3 to 0.8 of DC velocity value
o Constant heat flux boundary on both side of plate
o The test rig shall be capable of easily replacing the test article
o Response time shall be higher than 4Hz
o All Dimension shall be in the form of inch
Design Constraints
Some of the following constraints have been taken in to account in our design:
o Economic – although we have a large budget, we must be mindful of spending
o Safety – we are dealing with considerable amount of power, heat, and weight. Our design must
keep safety of the operator and surroundings in the forefront
o Modularity – the heatsink plates must be removable and must be able to be disassembled
o Longevity – the test bed needs to last a reasonable amount of time without service
Fan
o Capable of achieving relatively high cycle rates (~4 Hz in testing)
o Capable of max airflow requirement of 38 CFM
o Simple to control by manipulating voltage
o Issues : pressure differential too large for small fan
o Solution: increase fan size at the expense of cycle rate
Orifice Plate
o Measures flow rate
by restricting airflow
and measuring the
pressure drop
o Differential
manometer is used to
measure the pressure
drop
Hotwire Sensor
o Measures air velocity by heating a wire
to a constant temperature and
measuring the current in the wire
o We used this sensor because the orifice
plate would not arrive for over a month
and we needed data as soon as possible
Fan Controller Preliminary Testing
o Purpose is to determine the response of the fans
o Pitot tubes were used to obtain velocity data
o Data for the transient response was insufficient for a usable model. Sensor with improved transient
response needed.
Fan Controller
o Fan controller implements
the function
𝑉 = 𝐴(1 + β𝐶𝑜𝑠(2𝛑𝑓𝑡)
o β controls the amplitude of
the sine wave relative to the
DC value (30%-80%)
o f controls the frequency
(0.1 Hz – 1 Hz)
o A is set to maximize the
fans ability to push air
(control voltage should be
between 4 and 12 volts)
Function generations
Controller Housing
o Fan controller produces a lot of heat on the
FET transistor
o To dissipate this heat we built a channel to
carry it away from the FET and added a very
powerful fan and heat sink
Boost
Converter
Heat flow
Oscillator
FET
Controller
Thermocouple
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Type T Thermocouple
Operating range from 0 to 149 °C
0.08 seconds response time, higher than 10 Hz
Excellent accuracy
Good linearity
0.001" diameter thermocouple
Small output voltage( mV) must be amplified
Cold Junction Compensation
Thermocouples are differential not absolute.
Voltage produced at reference junction
(connector) depends on temperatures at both the
measurement junction and the reference
junction.
We must utilize equations provided by the
National Institute of Standards and Technology
(NIST) to determine the actual (absolute)
temperature at the measurement point.
Thermocouple Connectors
Allows connection of thermocouple alloy to copper for
PCB
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They provide a way to easily disconnect from the DAQ
They allow for low resistance connection to extensions
T thermocouple calibrated
ROHS compliant
Thermocouple Placement
The exact number of thermocouples was originally set to be 40 but was reduced to 20 because of cost
and space issues. They are placed along the center line of each plate.
The thermocouples near the inlet will be more closely spaced together than the thermocouples near the
end of the plate.
Inlet
Length: 60”
Width: 8”
Total Differential Pressure
o Measure pressure difference
across entire test bed
o Scrapped due to problems with
expected values from calculations
DAQ
Pre-built Option
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Ease of use
Verified
Compatibility
Expandability
Familiarity
Custom Option
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Flexibility
Customizability
Performance
Cost
DAQ Diagram
NI DAQ
Sensors
I/O
Modules
cDAQ
PC
Signal
Cond.
ADC
FPGA
USB
Controller
PCB
Dev Board
Hardware
NI 9211
◦ 14 Sps
◦ 4 Channel
NI 9213
◦ 75 Sps
◦ 16 Channel
24-bit resolution (0.2°C)
-40°C to 70°C range
Low noise
NI CompactDAQ
◦ USB
◦ LabVIEW, C, C++, C#, VB
◦ NI DAQ drivers, configuration, and
troubleshooting tools
◦ PC based data acquisition and logging
NI USB-6001
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14-bit
20 kSps
8 Channel
2 Outputs
LabVIEW
Output
Extra: Custom DAQ
Proof-of-concept
Viable alternative to pre-built solution
◦ Flexible
◦ Customizable
◦ Cost effective
Personal experience in:
◦ embedded systems
◦ hardware/software co-design
◦ FPGA design
DAQ PCB
o Designed in KiCAD
o Ordered from PCB-POOL
o 2-layer
o Custom footprints
o SMT components
o 18 TCs and 1 air-velocity sensor
FPGA Board
ZTEX USB-FPGA Module 2.01
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Open Source
Custom firmware
SDK and examples; ISE compatible
Configurable Flash and EEPROM
480 Mbit/s uplink rate
$108.90
Embedded Software
Written in Verilog using Xilinx ISE to
generate .bit file
Control
Utilization of open source code /
reference designs
◦ OpenCores, FPGALink, OpenADC,
ZTEX, Cypress
Focus on parallelization
SPI Master
Modules
Clock
Divider
Buffer
FIFO
Comm
USB
Interface
Firmware
o Written in C, compiled with SDCC
into .ihx
o Utilizes ZTEX headers
o Configures FX2 controller
o Slave FIFO IN mode
o Drives USB communication
o Cypress USB Control Center for
verification
Host Software
o Written in Java using ZTEX API
o Configure board with .ihx firmware and .bit embedded software
o Reading of incoming USB data
o Translation to real measurement values (°C, psi) (unfinished)
o Cold-junction compensation calculations (unfinished)
o Storage of data to file
o Display of data on customizable graphs/tables (scrapped)
o Control of serial sampling rates (scrapped)
Power Supply System
o Requirements:
o Input: 110V AC
o Output: +12V, -12V, 3.3V, and variable voltage for heaters
o Solution: computer power supply
and boost converters
o The boost converters translate the
12V from the PSU into a variable
output of 12-80V
Heaters
o Requirements:
o Heat the plates up to operating temperature
(~65 C) within a reasonable amount of time
o Capable of variable heat output
o Solution: Flexible rubber mat heaters
o Issues: 1 of the 8 heaters was from an odd
batch. Required a slightly different voltage
than the others
Power Requirements
Component
Voltage
Requirement
Current
Requirement
Amount in
System
12V
3A
1
Fan Controller 12V and -12V
20 mA
1
Heaters
10 A
2
Fan
12V
o Each boost converter draws up to 10 A
o Total draw for the system is 276 W
Budget
Part
Prototyping/Testing
Final
Fan
2 x $13 = $26
$15
Fan Control
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$50
Heaters
$47
8 x $75 = $600
Thermocouples
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$42
Thermocouple Adhesive
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$21
DC Power Supply
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$50
Wiring
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$15
DAQ
$400
$189+325+1066+720
Orifice Plate Assembly
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$235
Hotwire Sensor
$425
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Pressure Transducer
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$500
PCB
$19
$31
Total
$917
$3859
Questions?