Heat Conduction: In heat transfer, conduction (or heat conduction) is the transfer of heat energy by microscopic diffusion and collisions of particles or quasi-particles within a body due to a temperature gradient. The microscopically diffusing and colliding objects include molecules, electrons, atoms, and phonons. They transfer microscopically disorganized kinetic and potential energy, which are jointly known as internal energy. Conduction can only take place within an object or material, or between two objects that are in direct or indirect contact with each other. Conduction takes place in almost all forms of matter, such as solids, liquids, gases and plasmas. Thermal Conductivity of a metal: Thermal conductivity is a measure of the ability of a substance to conduct heat, determined by the rate of heat flow normally through an area in the substance divided by the area and by minus the component of the temperature gradient in the direction of flow, measured in watts per meter per Kelvin. Symbol: K is used to denote thermal conductivity.

1. Dept. of Mechanical & Production Engineering
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Ahsanullah University of
Science & Technology

2. Heat Conduction
Apparatus
Submitted By :
Istiak Ahmed (11.01.08.021)
Zaber Bin Ismail (11.01.08.020)
Rakibul Hasan (11.01.08.027)
Ovijit Das Gupta (11.01.08.061)
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3. General Review
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4. Purpose
The purpose of the project was to construct a heat conduction
apparatus which will measure the heat conductivity.
The objectives of the project were:
i. To have a basic concept on the heat conduction
ii. To learn to apply the concept on practical experience of heat conduction
process
iii. To gain experience about how the insulation system works, and applying it
to make an ideal one dimensional heat conduction system
iv. To measure the temperatures and thus calculation of the thermal
conductivity of a metal bar.
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5. Keywords
To quickly outline the primary goals, follow SAMPLE
Safety- minimal risk of student injury
Accuracy- correct measurements of conductivity
Mobility- can be maneuvered in and out of lab
Precision- measurements are easily repeated
Longevity- robust materials and long life span
Ease of use- simple assembly, disassembly, & cleaning
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6. Top Level Function
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7. Functional Decomposition
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8. Concept Generation
Review
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9. Heat Conduction
In heat transfer, conduction (or heat conduction) is the transfer
of heat energy by microscopic diffusion and collisions of particles or
quasi-particles within a body due to a temperature gradient. The
microscopically diffusing and colliding objects include molecules,
electrons, atoms, and phonons.
Thermal Conductivity of a metal
Thermal conductivity is a measure of the ability of a substance to
conduct heat, determined by the rate of heat flow normally through an
area in the substance divided by the area and by minus the component of
the temperature gradient in the direction of flow, measured in watts per
meter per Kelvin.
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10. Fourier’s law of Heat Conduction for one
dimensional plane wall:
According to the Fourier’s law for one dimensional plane wall,
Where,
Q = heat flow (by conduction) rate through the material
A = the section through which heat flows by conduction
The generalized heat conduction equation for constant thermal conductivity in Cartesian co-
ordinate is:
Where,
T =temperature distribution at the location x, y, z (0C)
x, y, z =co-ordinates
qm=internal heat generation rate per unit volume, (W/m3)
k=thermal conductivity of the material (W/mk)
α=thermal diffusivity (=k/ρc) of the material, (m2/s)
t=time, s
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11. Some assumptions that are given below can be followed to
simplify the generalized equation:
1) Heat flow is one-dimensional i.e. temperature, varies
along x-direction only. This is achieved by putting insulation on the
circumferential surface of the specimen.
2) End effect is negligible.
3) The specimen material is isotropic.
4) There is no internal heat generation in the specimen.
5) Steady state is achieved before final data recorded.
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12. Fundamental concept
A temperature gradient will be produced between a hot and cold
region
This gradient will be set across a span of heat conduction
The flow of energy will be allowed to reach steady state
The Energy In will be equivalent to the Energy Out
The temperature gradient will be measured with a transmission
system
Fig: Fundamental Concept of Heat Conduction Apparatus
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13. Design
The total setup design in Solidworks
Fig- Full Setup of the apparatus
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14. Here we used many equipments. Their design is given below:
Fig : Brass Bar Fig- Heating Coil
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15. Fig- Asbestos insulation and Drill holes inside Fig- Temperature controller
the wood support
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16. Here it shows the CAD diagram of the Top view of the heating box
showing how the coil does the coil stay here excluding the
insulation.
Fig- Top view of the heating box
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17. It is the Asbestos Insulation and it’s orientation inside the heating box
including the Heating Coil
Fig- Heating Box, Heating Coil and Asbestos Insulation
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18. Manufacturing
Brass bar
A 15 inch of Brass bar was selected and then after machining
it was brought as the desired shape. It is 13.8 inch long and the cross
sectional area is 1 inch square.
Then the bar was drilled into 5 different holes standing at 1.8
inch distance from each other. The first drilled hole was at 4.8 inch
distance from the left end of the brass bar.
Heating Coil
A Nichrome coil was made with a dimension of 8mm diameter
and 4 windings.
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19. Wood as Housing, Support and Insulation
Wood was used as the housing component that also serves
as the secondary insulating material. Some strong and straight
grained wood plates of irregular shape were chosen. While selecting
the wood plates it was kept in mind that the wood should be more
durable and can withstand higher temperature as the whole setup was
regarding to deal with the heat management. Then the wood plates
went under the process of machining and burnishing while making a
heating box, and support to the brass bar.
Asbestos
Asbestos has excellent thermal and insulation properties.
The heating coil is surrounded by asbestos that works as the primary
insulator. There is insulation of 1 inch of width of asbestos that were
constructed with four different plates. Width of the each plate is 0.25
inch.
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20. White Cement
The plates are sticked to each other with white cement. White
cement was used mainly as the sticky component that also works as
the high temperature insulation. The asbestos is naturally porous and
brittle material, white cement adds more stiffness to the asbestos and
thus it acts as a better insulator.
Thermocouple
Thermocouple is a temperature-measuring device consisting
of two dissimilar conductors that contact each other at one or more
spots. Commercial thermocouples are inexpensive, interchangeable,
are supplied with standard connectors, and can measure a wide range
of temperatures. In contrast to most other methods of temperature
measurement, thermocouples are self powered and require no external
form of excitation.
In our experiment, K Type thermocouples were used because of its
wide variety of probes and easily available in market.
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21. Digital Temperature controller
This is the device which shows the temperature of the
thermocouples. In our experiment, we used a dual display
universal digital programmable temperature controller.
Voltage Regulator or Variac
Variac is mainly known as variable auto-transformer.
This is an electrical device that regulates the voltage from a
voltage source.
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22. Calculation
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23. Graphs
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25. By experiment and proper calculation we get
The Thermal Conductivity of Brass is 74.614 Wm-1k-1.
The percentage of error is 35.118 %
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26. Application
It is actually a laboratory equipment. The application of the
apparatus is to measure the thermal conductivity of a metal.
Here, we used Brass as the metal.
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27. So, this is all about this project. Here we
mentioned the basic concept of Heat
Conduction, Fourier’s Law for one
dimensional heat transfer, the design and
manufacturing.
Here we also mentioned about the
application of ‘Heat Conduction Apparatus’.
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28. Thank You All
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29. Any Question
?
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