Conductive heat transfer lab #2
Table of Contents
1. COMPONENTS
1
A. MAIN UNIT
B. COOLING UNIT
C. POWER SUPPLY
D. LIGHT BAR
E. CONTROL BOX
F. COMPUTER WITH LABVIEW (OPTIONAL)
G. SAMPLES
1
2
2
2
2
2
2
2. SETUP
3
A. MAIN UNIT PREPARATION
B. COOLANT PREPARATION
C. ELECTRICAL PREPARATION
3
3
3
3. LAB PROCEDURE
4
4. EXAMPLE EXPERIMENTS
4
SAMPLE MATERIAL
SAMPLE DIAMETER
SAMPLE LENGTH
SAMPLE SHAPE
CONTACT PRESSURE
CONTACT RESISTANCE
COOLANT EFFECT
POWER SUPPLY
4
4
4
4
5
5
5
5
5. STORAGE
5
1. Components
A. Main unit
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Thermistor arms (6 + 4 extra)
Transistor mounting bracket
Flux transistors (2)
Cold plate
Cold water tubes and quick release (2)
Pressure sensor
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Heater
Heater Assembly
Communications cable
B. Cooling unit
C. Power supply
D. Light bar
E. Control box
F. Computer with labview (optional)
G. Samples
2. Setup
A. Main Unit preparation
1. Position unit so that the crank handle is perpendicular to the
surface and the door is facing towards the user
2. Remove thermistor mounting bracket from the unit
3. Position thermistor arms on the mounting bracket and tighten
down using an allen wrench. Note the position number.
4. Attach main cable to transistor units (red wire is power).
Thermistor cables are non-polar (order of wires does not
matter). The pair of wires that says 1 should be closest to the
heater, while the largest number should be closest to the cold
plate.
5. Connect remaining wires (i.e. pressure sensor, cold top, cold
bottom, heater). Note, all connections are non-polar
6. Insert thermistor mounting bracket into main unit
7. Insert sample into unit and tighten hand crank. Be sure that the
sample is centered over the flux thermistor and that it is flush
again the surface (to maximize heat transfer and minimize
contact losses).
8. Position the mounting bracket such that there is a slight bend
in the thermistor arms. Tighten down the mounting bracket
9. Close and secure door
B. Coolant preparation
1. Fill the tower with fluid (water or ethylene glycol)
2. Connect the supplied tubing to the cooling tower
3. Insert the open (non-barbed) end into the quick release at the
base of the main unit. Repeat for the second tube
C. Electrical preparation
1. Plug the main cable into the control panel
2. Plug the light strip into the control panel into the “A type” USB
port
3. Plug the power supply cables (red and black) into the control
panel
4. Plug the control panel power supply into the “B type” USB port.
Plug the free end into the computer for labview use or the
power supply unit for standalone use
5. Plug the power supply into a wall outlet or other power source
3. Lab Procedure
A. Turn on coolant tower and set to desired temperature
B. Turn on power supply using the switch in the rear
C. Set desired voltage (max 24 V) or current (max 2A). DO NOT YET
PRESS THE CENTER BUTTON
D. Open supplied labview program
a. Check thermistors in use and set location on mount
b. Enter voltage and current of the power supply
c. Set contact pressure to desired value by tightening or
loosening hand crank
E. Be sure the LCD screen is on and the led lit
F. Turn on power supply by pressing the center button on the unit and
by flipping the switch on the control panel to the on position
G. If data taken manually: record temperature data every 3 minutes
H. If data taken automatically: visually observe the temperature profile
in the labview interface and the calculated thermal conductivity
I. Allow 40 to 60 minutes to reach steady state
J. Note: when switching samples or when repeating tests, carefully
remove the sample by releasing pressure on the crank. Handle HOT
sample with proper PPE (i.e. gloves) and immerse sample in room
temperature water. Completely dry before reinserting into main unit
4. Example Experiments
Sample material
1. Test the thermal conductivity of various materials
2. Maintain diameter and length of materials
3. Aluminum and Copper samples provided (with comparable
dimensions)
Sample diameter
1. Test the thermal conductivity of various diameter samples
2. Maintain length and material type
3. Copper samples provided
Sample length
1. Test the thermal conductivity of various length samples
2. Maintain diameter and material type
3. Copper and aluminum samples provided
Sample shape
1. Test the thermal conductivity of various shapes of samples
(cylinders vs. squares vs. rectangles)
2. Maintain material type and length
3. Samples NOT provided
Contact pressure
1. Test the thermal conductivity of a single samples with various
pressure applied by the hand crank
Contact resistance
1. Test the thermal conductivity of samples with various edge
finishes (polished vs. rough vs. partial contact due to edge or
missing material)
2. Maintain material type, diameter and length
3. Samples provided
Coolant effect
1. Test the thermal conductivity of samples with coolant supplied
to one side vs. lack of coolant
2. Done with one sample by running test with coolant tower
running and again without coolant tower running
Power supply
1. Test the thermal conductivity of a single sample by changing
the power supplied to the unit (i.e. vary voltage or current)
5. Storage
A. Unplug the main cable from the control panel, leaving internal
connections intact
B. Unplug all connections to the power supply and control unit. Store in
main unit
C. Store light bar inside main unit
D. Store excess thermistors in main unit
E. Remove connection to cooling tower by removing barbed ends
F. Wrap main cable around door handle
G. Compress crank to reduce area