King Saud University dep Chemical Engineering College of Engineering ID: 426103592 Name: Mohammad.o. Dr : malik Al- ahmad Heat transfer by conduction.

King Saud University dep Chemical Engineering College of Engineering

ID: 426103592 Name: Mohammad .o.

Dr: malik Al- ahmad

Heat transfer by conduction

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:-

SubstanceThermal Conductivity k [J/(s-m-C)]

SubstanceThermal Conductivity k [J/(s-m-C)]

Syrofoam     0.010Glass     0.80

Air     0.026Concrete     1.1

Wool     0.040Iron     79

Wood     0.15Aluminum     240

Body fat     0.20Silver     420

Water     0.60Diamond    2450

##One –Dimensional, steady –state heat One –Dimensional, steady –state heat conductionconduction -: -:

-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