Composite Materials Engineering
ENGR 451 Transport Phenomena Laboratory
Heat Convection
OUTCOMES
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Define heat convection and its importance.
Define heat convection coefficient.
Explain how heat convection coefficient can be calculated and/or measured.
List all the parameters that can affect the heat convection coefficient.
Name the dimensionless numbers that affect the heat convection coefficient.
Measure the convection heat transfer coefficient of air flowing over a warm
geometry.
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INTRODUCTION
Read Sections 7.2, and 7.6 of Fundamentals of Heat and Mass Transfer (6th edition) by Incropera,
DeWitt, Bergman, and Lavine.
MATERIALS AND EQUIPMENT
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Armfield Free and Forced Convection Heat Transfer apparatus.
Anemometer
Heat convection surface block
Heat conducting compound
PROCEDURE
1. Plug in the electric console.
2. Clean and place the heating block into the air duct and secure it using the two clamps on
the backside of the Armfield apparatus. Connect the cords to their proper places on the
power supply/meter unit.
3. Measure the ambient air temperature in the column.
4. Turn on the electric console using the "supply" switch.
5. Set the heater power control to 20 Watts.
6. Plug the connecting lead into the thermistor sensor on the side of the heating block.
Connect the other end to the console. This will allow the measurement of the block
temperature.
7. Set the fan speed to the designated location.
8. Allow at least 50 minutes for the block temperature to achieve steady state conditions.
Make sure that the tip of the temperature probe is coated with the conducting compound.
How do you know that you have achieved steady state?
9. Record the temperatures at all the possible locations. Confirm with the instructor.
10. Record the air temperature before and after passing the heating geometry.
11. Turn the fan speed and the heater power control back to zero. Turn the electric console
"supply" switch off and allow the block to cool.
Do not try to remove block until sufficiently cooled. Failure to do so may result in serious
injury. WEAR PROTECTIVE GLOVES.
13. Once the block has cooled sufficiently, disconnect the clamps and replace it with the
second assigned block geometry.
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