King Saud University
Chemical Engineering College of Engineering dep
Heat transfer by conduction
Name: Mohammad .o.
Dr: malik Al- ahmad
ID: 426103592
Contents:1)……. Modes of heat transfer.
2)……. Mechanisms of heat conduction.
3)……. Fourier Law of Heat Conduction.
4)……. Thermal Conductivities.
5)……. One –Dimensional, steady –state heat conduction:-the plane wall.
-the cylinder.
-The sphere.
-the composite wall.
Modes of heat transfer:-
((There are three fundamental types of
heat transfer one of them is
conduction.))(1)
Conduction:((Is the transfer of Heat from one part
of a body to another part of the same
body, Or from one body to another in
physical contact with it ,without
appreciable displacement of the
particles of the body.)) (1)
Mechanisms of heat conduction:((In a solid, the flow of heat by conduction is the
result of the transfer of vibrational energy from one
molecule to another.
In fluids: it occurs in addition as a result of the
transfer of kinetic energy.
Heat
transfer by conduction may also arise from the
movement of free electrons, a process
Which is particularly important with metals and
accounts for their high thermal conductivities.
It is need a medium to transfer, and moves from high
region to low region.)) (2)
Fourier Law of Heat Conduction:-
Q/A=-k*(dT/dx)
This equation determines the heat flux vector
q for a given temperature profile T and
thermal conductivity k. The minus sign
ensures that heat flows down the temperature
gradient
#Thermal Conductivities:Substance
Thermal Conductivity
Substance
Thermal Conductivity
k [J/(s-m-C)]
k [J/(s-m-C)]
Syrofoam
0.010
Glass
0.80
Air
0.026
Concrete
1.1
Wool
0.040
Iron
79
Wood
0.15
Aluminum
240
Body fat
0.20
Silver
420
Water
0.60
Diamond
2450
#One –Dimensional, steady –state heat
conduction:-the plan wall.
-the cylinder.
-the sphere.
-composite wall.
# the plane wall#
The cylinder#
#
A)
One layer
B) multilayer
the sphere#
#
#the
composite wall#
#Refrance#
1) R.H. Perry and C.H. Chiton, Eds, chemical engineering Hand book.
2) J.m.coulson and J.F.Richard son.eds, chemical engineering.
(3) M.Necatiozisik, Heat transfer.
(4) Incropera, Dewitt, Bergman, lavine, Fundamentals of Heat and Mass
transfer, 5th edition.
The End