Abstract
This report discuses heat transfer by conduction in four different units, which are: unit
#1, unit #2, unit #3, and unit #4. In this experiment we study unit #4 twice:
Unit #4a, where the power input was about 750 watts
Unit #4b, where the power input was reduced to half of that used in unit #4a.
Our objective in this experiment is to calculate the mass flow rate of water and thus the rate of
heat transfer for each unit can be also calculated, and to find the barrier resistance between
different joint metals. This was achieved by heating one end of the conducting bar. Water was
passed over the bar and its incoming and leaving temperature was recorded. For example, the
% of error results from comparing Q
exp.
And Q
ther
. In units # (3, 4a,4b) were :
23.7
%
 for unit 3
53.6
%
 for unit 4a
25.9 %
 for unit 4b
INTRODUCTION
Heat transfer accrues in three ways conduction, convection, and radiation. Heat transfer
by conduction is best done in solids where the thermal conductivity is high. Heat
transfer by
conduction accrue as a result of temperature difference between two bodies in contact with
each other. So , heat moves from the higher temperature to the lower temperature object. It
result from molecular interaction between adjacent molecule. Also, there another mechanism
which is caused by free electron which accrue in free metallic solids.
THEORETICAL BACKGROUND
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Fourier’s law describes heat transfer by conduction.
Q
x
/A= kdT/dx
 1)
Where k is the thermal conductivity of the material which
is a function of temperature for the
case of solids. and Qx is the rate of heat transfer
K = k
o
(1+
β
T)
2)
It is known that any two materials can not have a perfect contact between them , so when heat
moves through this empty space
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 Fall '09
 M.Elgaily
 Thermodynamics, Heat, Heat Transfer, heat sink

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