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experiment to determine thermal coinductitivy
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FORCED CONVECTION HEAT TRANSFER
06-92-328-01/02 HEAT TRANSFER
Summer 2015
Graduate Assistant: Prashant Kaliram Pradip
Introduction
Forced convection heat transfer theory is valuable in many engineering fields
Especially heat-exchanger design
This apparatus allows to examine the theory & formulae related to forced convection in pipes
Tuesday, July-14-15 Pradip 2
General Layout
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Airflow Speed
The fan runs at a constant speed and draws air through a control valve
The air speed is varied by screwing in the plate over the fan inlet
Do not screw the plate fully in, there must be an airflow!
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Orifice Dimensions
Tuesday, July-14-15 Pradip 5
Pitot Tube
Pitot tube traverse assembly measures:
Velocity and temperature profile across the test pipe
Outer Diameter of Pitot tube 3 mm
Tuesday, July-14-15 Pradip 6
Dimensions and Positions of Thermocouples
Thermocouple selector is adjusted to measure the temperature from thermocouple 1 to 14.
Maximum duct temperature < 150C!
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Procedure
Start the fan. When air is flowing through the tube, slowly increase the electrical
current to the heating coil until a suitable value is reached. Run for 15 to 20 minutes, by which it will have reached an equilibrium
temperature. Check this by monitoring one of the thermocouples. Note down the Orifice pressure drop from the manometer. Take readings of temperature distribution across the duct by changing
the thermocouple selector. Set the Pitot tube right against the far side of the duct and take
readings of temperature from 14 in thermocouple selector. Without altering the current setting, traverse the Pitot tube across in
intervals of 2 mm, and not the results. After use, turn off the heater but allow the fan to keep working for
approximately five minutes before you switch it off.
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Data collection sheet
THERMOCOUPLES
Number Position Temperature (C)
1
Outer
surface of
copper
tube
2
3
4
5
6
7
8 Inner
surface
insulation
10
12
9 Outer
surface
insulation
11
13
Distance from pipe wall (mm) Temperature (C)
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
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Orifice pressure drop (mm H2O):
Experimental Information
Video conference
Fill the tabular column as the camera is focused on the data
The data to be noted will be shown in the computer screen
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Tasks associated with the laboratory
Plot the temperature transverse as a function of distance from pipe wall.
Calculate the heat input to the air through thermocouple 1 to 7 from equation 8.
Determine the heat transfer coefficient from tube to air with equation 4.
Calculate the non-dimensional numbers and compare with Dittus and Boelter empirical relationship.
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Instructions for preparation and submission of the lab report
You may work in groups of up to four. Each person will write and sign their name on the
title page of the submitted laboratory report, and provide an e-mail address.
Prepare a short lab report (no more than 3 pages) including the data collection sheet provided above.
Explain your results and complete all tasks as specified above.
Each group should submit a hard copy of the lab report no later than July 22, 2015. No late submissions will be accepted.
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THANK YOU
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