Advanced Heat Mass Transfer

Assignment Writing Service
http://StudyHub.vip/Advanced-Heat---Mass-Transfer 👈

1. Advanced Heat & Mass Transfer
Dr Muhammad Anwar
Assistant Professor
Email: [email protected]
Department of Mechanical Engineering
Institute of Space Technology

2. Course Text and References
Course text:
Title: Heat and Mass Transfer – A practical Approach by
Yunus A. Cengel, 3rd Edition, McGraw Hill.
Relevant references:
Heat Conduction by M. Necati Ozisik, 2nd Edition, John Wiley and
Sons Inc.
Convection Heat Transfer by Tuncer Cebeci, 2
nd
Edition, Springer.
Fundamentals of Heat and Mass Transfer by M. Thirumaleshwar,
Pearson Education.
Lecture notes will be provided at the end of
each lecture.

3. Course Contents
Introduction to Heat & Mass Transfer
Conduction
Heat conduction in Cartesian coordinates (One-dimensional and
multidimensional), steady and transient state, industrial Cartesian systems
analysis and problem solving.
Heat conduction in cylindrical coordinates (One-dimensional and
multidimensional), steady and transient state, practical cylindrical systems
analysis and problem solving.
Heat conduction in spherical coordinates (One-dimensional and
multidimensional), steady and transient state, practical spherical systems
analysis and problem solving.
Analytical and Numerical Methods of solving heat conduction problems.
Conduction with moving heat transfer sources.

4. Convection

Fundamentals of Convection, physical Mechanism, Classification of
fluid flows, Velocity and thermal boundary layers, Laminar and
Turbulent flows, Heat and Momentum transfer in turbulent flow.
Derivation of differential convection equations, Solutions for
convection equations for a flat plate, Non-dimensionalized convection
equations and similarity, Functional form of friction and convection
coefficients, Analogies between momentum and heat transfer.
External forced convection, drag and heat transfer in external flows,
parallel flows over plates, flow across cylinder and spheres.

Course Contents

5. Internal forced convection, the entrance region, laminar flow in tubes
Turbulent flow in tubes
Boiling heat transfer
Condensation heat transfer
Radiation Heat Transfer, Mass Transfer
Introduction to thermal radiation, radiative exchange in semitransparent
mediums, the electromagnetic spectrum; the blackbody.
Wave phenomena versus geometric optics, polarization, diffraction, and
refraction effects; emission, reflection, absorption, and transmission of
thermal radiation by surfaces.
Analogy between heat and mass transfer, mass diffusion, boundary
conditions, steady mass diffusion, transient mass diffusion, mass
convection.
Course Contents

6. Course Grades
Grades will be based on:

1.Assignments (5-10%)
2.Quizzes (10-15%) Announced & un-announced
3.Course/Term project (15-20%) Submission 15
th
Week
4.Two OHT’s (25-30%)
5.Final Exam (40-50%)

All write ups that you present MUST contain Your name and
Registration Number

7. Academic Integrity
Students are encouraged to collaborate in the
solution of HW problems and assignments, but
submit independent solutions that are NOT
copies of each other. Funny solutions (that
appear similar/same) will be given zero credit.
Software may be used to verify the HW
solutions. But submission of software solution
will result in zero credit.

8. Assignments
Be as detailed and explicit as possible. For full
credit Do NOT omit steps.

Only neatly written assignments will be
graded

Late Assignments will NOT be accepted.

9. Course Project
Submit 1-page project proposal latest by 3
nd
week (in
class). The earlier the better.
5-minute presentation will be required from each of you
in 4
rd
week
In the course project you will be required to
Choose an engineering system
Develop a mathematical model for the system
Develop the numerical model
Solve the problem using commercial software
Present a convergence plot and discuss whether the mathematical model
you chose gives you physically meaningful results.

10. Course Project
Submit a one-page progress report on 7
th
week (this will count as
5% of your project grade)
A Final presentation of 15 min + 5 min (Q/A) will be required
in 15
th
week.
Submit a project report (typed) by 15
th
week to the instructor.
Project report Must be professional (Text font Times 11pt with
single spacing) and Must include the following sections:
Introduction & Background
Problem Statement
Analysis
Results and Discussions

11. What is difference b/w Thermodynamics
and Heat transfer?
 Thermodynamics :
Deals with the amount of heat transfer as a system undergoes
from one state to other equilibrium state.
Heat Transfer :
1.In engineering we are normally interested in the rate of heat
transfer. How much heat is transfer per unit of time.
2.As well as the temperature distribution within the system at a
specified time.

12. Thermodynamics tells us:
How much heat is transferred (?Q)
How much work is done (?W)
Final state of the system
Heat transfer tells us:
How (with what modes) ?Q is transferred
At what rate ?Q is transferred
Temperature distribution inside the body
What is difference b/w Thermodynamics
and Heat transfer?
Heat transfer Thermodynamics complementary

13. Heat Transfer?
 Heat Transfer :

1.Heat can transferred from one system to other due to the
temperature difference

2.It is science which predict the heat energy transfer between
material bodies as a result of temperature difference.

Pipe flow
Pressure
Difference

Current flow
Voltage
Difference

14. Human Comfort
A human body is
continuously rejecting
heat to surrounding.
Heat Transfer
Human comfort is directly related to rate of heat
rejection (Heat Transfer rate).

15. Daily Life Examples
Heat Transfer
 Heating & Air-Conditioning System
 Refrigerator, Iron
 Computer
 Energy Efficient Home
 Car Radiators
 Solar Collectors

16. Why we need a detailed study of
Heat Transfer ?

17. Heat Transfer indicates how long process will take.
Why we need a detailed study of Heat Transfer ?
A designer of thermos
normally interested in
that how long coffee will
sustain its temperature

18. Engineering Heat Transfer Applications
1.Heat Exchangers

2.Boilers

3.Condensers

4.Radiators

5.Heaters
Rating : Determination of HT for an
existing system at a specific
temperature difference
Sizing : Determination of size of a
system in order to transfer heat as a
specified rate for a specific
temperature difference

19. Some more applications of heat transfer
Energy production and conversion
- steam power plant, solar energy conversion etc.
Refrigeration and air-conditioning
Domestic applications
- ovens, stoves, toaster
Cooling of electronic equipment
Manufacturing / materials processing
- welding, casting, soldering, laser machining
Automobiles / aircraft design
Nature (weather, climate etc)

20. Thermal Energy (Q) = 1 joule
Units
Heat Transfer rate (q-dot) = 1 joule/sec = 1 watt
Heat Flux (q/A) = 1 watt/m
2

21. Energy :
•Thermal
• Chemical, Nuclear
• K.E, P.E
• Mechanical
• Electrical

Heat & other forms of Energy

22. Internal Energy (U) :
Sum of all microscopic forms of energy of molecules.
U = K.E + P.E
Portion of K.E = Sensible Energy or Heat
Heat :
Temperature :
Total K.E of molecules
Average K.E of molecules
Heat & other forms of Energy

23. Internal Energy
Associated with Atomic
bonds in a molecule is
called Chemical energy
Associated with bond within the
Nucleus of the atom is called
Nuclear Energy
This energy is released during the chemical or
Nuclear reaction
Heat & other forms of Energy

24. Calorie :
Heat & other forms of Energy
Calorie is a unit of Heat Energy. Like Joule
1 Cal = 4.1868 Joule
1 Cal = Amount of heat required
raise the temperature of one gram
of water at 14.5°C by 1°C

25. Specific Heat:
Heat & other forms of Energy
Amount of heat required raise the temperature
of a unit mass of a substance by 1°C
At Constant
Volume
(Cv)
At Constant
Pressure
(Cp)
For incompressible substance it is constant
C = f ( P,T )
UNIT ?

26. Specific Heat:
For an ideal gas , specific heat normally
depends only on temperature.
du = Cv(T) dT dh = Cp(T) dT
Sum of internal energy and energy required to flow of
fluid
h = u + Pv
Enthalpy
UNIT ?
Heat & other forms of Energy

27. Latent Energy or Heat :
If energy (Heat) supplied to the system is greater than
Molecular force  phase change
Amount of heat require to change the phase is called Latent heat.
Heat & other forms of Energy

28. In Heat Transfer, Normally we are interested in the Thermal energy
which is transferred due to temperature difference.

And, All Nuclear, Chemical, etc energies consider in the form of thermal
energies as heat generation;
system
thermal
gen
out
in
E
E
Q
Q





Energy Balance in Heat Transfer
Heat Transfer
Heat & other forms of Energy

29. Conduction

Convection

Radiation

Modes of Heat Transfer

30.  Conduction :
Transfer of heat through solids or stationary fluids
Modes of Heat Transfer

31. Heat Conduction
Mathematical Modeling :

1






x
Q
A
Q
T
Q









x
A
k
-




T
Q


x
A





T
Q

0)
x
(

x
kA
-




d
dT
Q

Fourier’s law of conduction

32. Mathematical Modeling :
x
kA
-

d
dT
Q


k = Thermal Conductivity
-ive sign shows that heat is conducted in
the direction of decreasing temperature.

ΔT becomes negative, so heat transfer is +
ive.

A is ┴ to the heat transfer
Heat Conduction

33. Thermal Conductivity :
k


A
x




T
Q


x
A
k
-




T
Q

Rate of heat transfer through a unit
thickness of material per unit area
and per unit temperature difference.
UNIT ?
Heat Conduction

34. Thermal Conductivity :
Why Gases have
lower thermal
conductivity than
Solids?
Why metals have
higher thermal
conductivity than
Solids?
Heat Conduction

35. The mechanisms of heat conduction in
different phases of a substance

36. Thermal conductivity & temperature

37. Heat Capacity
Storage capability of material per unit volume
Thermal Diffusivity
How fast heat diffuses through a materials
 
p
C

 

p
C
k



Stored
Heat
Conducted
Heat


Higher or lower,
which one is better ?
UNIT ?
Heat Conduction

38.  Convection :
In this mode heat is transfer due to the movement
of the fluids
Modes of Heat Transfer

39. Heat Convection
Free
Convection
Forced
Convection

40. Hot Iron Block…
(T1 = 400°C)
Cool Air
(T∞ = 15°C)
By Speed
Type of
fluid
(Water)
µ, ρ, C, v
…..
Roughness, Geometry
of the object
Nature of
the flow

41. Mathematical Modeling :
The rate of heat convection over a medium depends on the:
 Nature of the flow (Re….Laminar or Turbulent)
 Nature of the fluid (Viscosity, ‘k’, density, C, etc)
 Surface Area of the medium
 Temperature Difference
Unlike conduction, convection is not
concerned with medium properties
s





A
Q
T
Q





Heat Convection

42. Mathematical Modeling :
A
Q
T
Q










A


s
T
h
Q




A


s
T
Q



Newton’s law of cooling
Convective heat
transfer Coefficient
(Nature of the fluid)
where; ΔT = (Ts -T∞)
Heat Convection

43. Convective heat transfer Coefficient (‘h’)
Rate of Heat transfer b/w solid surface and a fluid per unit
surface area per unit temperature difference
Units :

A
s
T
Q
h



‘h’ : (W/m
2
/°C)
Heat Convection

44.  Radiation :
It does not require any medium for heat transfer. In
this mode the electromagnetic radiation is emitted by an
object for heat transfer.
Modes of Heat Transfer

45. The maximum rate of radiation that can be emitted from a
surface at an absolute temperature T
s (in K) is given by
Stefan–Boltzmann law
Stefan–Boltzmann constant

46. Radiation Heat Transfer
The radiation emitted by all real surfaces is less than the
radiation emitted by a blackbody at the same temperature,
and is expressed as

47. When a surface of emissivity ? and surface area As at an
absolute temperature Ts is completely enclosed by a much
larger (or black) surface at absolute temperature Tsurr
separated by a gas (such as air) that does not intervene with
radiation, the net rate of radiation heat transfer between
these two surfaces is given by

Radiation Heat Transfer

48. The driving force for heat transfer is the temperature difference. In
contrast, the driving force for mass transfer is the concentration difference.
ANALOGY BETWEEN HEAT AND MASS TRANSFER
There is close resemblance between heat and mass transfer relations.
Temperature
Mass Transfer

49. Thank You