COURSE: CHE 322 – HEAT TRANSFER (3 Credits /Compulsory).
Course Duration: Three hours per week for 15 weeks
As taught in 2010/2011 session
LECTURERS:
1
Prof. OGUNNIYI,D.S.
Ph.D (Loughborough),MSc., B.Sc, MNSChE, MCSN, FICCON, MNSE, Reg. Engr (COREN)
E-mail: dsogunniyi@unilorin.edu.ng
Office Location: Rm 5, First Floor,Department of Chemical Engineering Building.
Consultation Hours:
2
OGUNLEYE,Oladipupo Olaosebikan
Ph.D ,MSc.,B.Tech. Reg. Engr.(COREN), MNSChE,MAIChE,MSIAM.
E-mail: ooogunleye@yahoo.com
Office Location: – Rm 5, Ground Floor,Department of Chemical Engineering Building
Consultation Hours: 11.00-1.00pm Mondays and Wednesdays.
Developer: Dr OGUNLEYE,Oladipupo Olaosebikan
Course Content:
Introduction and concepts on the mechanism of heat flow. Steady state conduction in one
direction. Steady state conduction multiple direction. Heat transfer to fluids without phase
change. Heat transfer to fluids with phase change. Radiation heat transfer. Heat transfer
equipment. Calculation of heat transfer coefficients. Evaporators, Re - boilers, Condensers and
furnaces.
45h (T) PR: MEE 242 C
Course Description:
Production or absorbtion of energy in the form of heat transfer are carried out in almost
all chemical processes.This heat transfer may take the form of conduction,convection or
radiation.The course is intended to teach the laws governing these various forms of heat transfer,
their applications in chemical process engineering, the types of apparatus involved in heat
transfer, maintenance and control.
1
Course Justification:
In the majority of chemical processes, heat is either
given out or absorbed, and fluids must often be either
heated or cooled in a wide range of plant, such as
furnaces, evaporators, distillation units, dryers, and
reaction vessels where one of the major problems is
that of transferring heat at the desired rate. It may also
be necessary to prevent the loss of heat from a hot
vessel or pipe system. The control of the flow of heat
at the desired rate forms one of the most important
demands on a Chemical Engineer especially in the
present world where cost of energy is sky rocketing.
An in-depth knowledge of the mechanism of heat
transfer will be of great advantage in devising ways
of minimizing energy losses of various forms and
thereby reduce the cost of operation.
Course Objectives:
The objective of this course as an integral part for the award of B. Eng. Chemical
Engineering is for the students
to have an understanding of the fundamental principles
underlying the principles of heat transfer in chemical processes. It is also aimed at introducing
the unit operations available for heat transfer processes.
Course Requirements:
This is a compulsory course for all students studying Engineering In view of this, students
are expected to participate in all the course activities and have minimum of 75% attendance
to be able to write the final examination.
Methods of grading:
No
1.
2.
3.
Item
Assignment/ Quiz / Monthly Test
Mid Semester Test
Examination
Total
2
Score %
10
20
70
100
Course Delivery Strategies:
The lecture will be delivered through face-to-face method, lecture guide (lecture note) will be
provided during lectures. Students will be encouraged and required to read around the topics.
The delivery strategies will also be supported by tutorial sessions.
LECTURES
Week 1-2 : Introduction and Concepts on the Mechanism of Heat Flow
Objective: The students should be able to describe various modes of heat transfer, other basic
terminologies and considerations during heat transfer processses
Description: The course outline will be introduced with emphasis on the objectives and delivery
strategies, explanation of the principles of conduction, convection and radiations.
Individual and overall coefficients of heat transfer. Mean temperature difference
Study Question:
1. Describe the term “ heat transfer”?
2. Explain the three basic mechanism of heat transfer?
3. Briefly explain the following terms: (i) Conduction (ii) Convection (iii) Radiation
4. Distinguish between natural and forced convection.
5. A heat exchanger is required to cool 20 kg/s of water from 360 K to 340 K by means of 25
kg/s water entering at 300 K. If the overall coefficient of heat transfer is constant at 2
kW/m2K, calculate the surface area required in (a) a countercurrent concentric tube
exchanger, and (b) a co-current flow concentric tube exchanger.
Reading List:
1 McCabe1,W. L., Smith,J.C. & Harriott, P.(1993). Unit Operations of Chemical
Engineering. Fifth Edition. McGraw Hill Co. Singapore. (pp.285-288 ). ISBN 0-07112738-0
2 Coulson4, J.M., Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 1, Sixth Edition, Butterworth Heinmann Inc. Oxford. (pp381-386).
ISBN 0 7506 4444 3
3 Kern4, D.Q.(1965). Process Heat Transfer. International Edition. McGraw Hill Co.
Singapore. (pp.1-5).ISBN 0-07-085353-3
Week 3 - 5:
Objective:
Heat Transfer by Conduction
Students shoul have an understanding of the mechanism of heat transfer by
conduction.
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Description: Steady state conduction: Conduction through a plane wall ,Thermal resistances in
series, Conduction through a thick-walled tube, Conduction through a spherical
shell and to a particle. Unsteady state conduction. Student will also be assessed on
the topics covered so far through a short Quiz.
Study Question:
1. Estimate the heat loss per square metre of surface through a brick wall 0.5 m thick when
the inner surface is at 400 K and the outside surface is at 300 K. The thermal conductivity
of the brick may be taken as 0.7 W/mK.
2. Derive the equation for steady state heat transfer through a spherical shell of inner radius
r1 and outer radius r2.Arrange the result for easy comparison with the sultion for a thickwalled sylinder.
3. A tube 60mm(2.36in.) OD is insulated with 50mm(1.97in.) layer of silica foam,for
which the conductivity is 0.055W/m.0C (0.032Btu/ft-h-0F),followed with a 40mm(1.57
in.) layer of cork with conductivity of 0.05W/m.0C (0.03Btu/ft-h-0F). If the temperature
of the outer surface of the pipe is 1500C (3020F) and the temperature of the outer surface
of the cork is 300C (860F), calculate the heat loss in watts per meter of pipe.
4. A cooling coil, consisting of a single length of tubing through which water is circulated,
is provided in a reaction vessel, the contents of which are kept uniformly at 360 K by
means of a stirrer. The inlet and outlet temperatures of the cooling water are 280 K and
320 K respectively. What would be the outlet water temperature if the length of the
cooling coil were increased by 5 times? Assume the overall heat transfer coefficient to be
constant over the length of the tube and independent of the water temperature.
5 A furnace is constructed with 0.20 m of firebrick, 0.10 m of insulating brick, and 0.20 m
of building brick. The inside temperature is 1200 K and the outside temperature is 330 K.
If the thermal conductivities are as shown in Figure below, estimate the heat loss per unit
area and the temperature at the junction of the firebrick and the insulating brick.
Reading List:
1 McCabe1,W. L., Smith,J.C. & Harriott, P.(1993). Unit Operations of Chemical
Engineering. Fifth Edition. McGraw Hill Co. Singapore.(pp.289-305).ISBN 0-07112738-0
2 Coulson4, J.M. ,Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 1, Sixth Edition, Butterworth Heinmann Inc. Oxford. (pp 387
-414). ISBN 0 7506 4444 3
3 Coulson4, J.M. ,Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 3, Sixth Edition, Butterworth Heinmann Inc. Oxford.(pp 125216 ). ISBN 0 7506 44950 X
4 Kern4, D.Q.(1965). Process Heat Transfer. International Edition. McGraw Hill Co.
Singapore. (pp.6-24). ISBN 0-07-085353-3
4
Week 5 - 8:
Heat Transfer by Convection.
Objective: Students should have an understanding of the mechanism of heat transfer by
convection.
Description: Natural and forced convection, application of dimensional analysis to convection,
forced convection in tubes, convection to spherical particles, natural convection,
heat transfer from condensing vapours, heat transfer to boiling liquids. Student will
also be assessed on the topics covered so far through a short Quiz.
Study Question:
1. 14.4 tonne/h (4.0 kg/s) of nitrobenzene is to be cooled from 400 to 315 K by heating a
stream of benzene from 305 to 345 K. Two tubular heat exchangers are available each
with a 0.44 m ID shell fitted with 166 tubes, 19.0 mm OD and 15.0 mm ID, each 5.0 m
long. The tubes are arranged in two passes on 25 mm square pitch with a baffle spacing
of 150 mm. There are two passes on the shell side and operation is to be countercurrent.
With benzene passing through the tubes, the anticipated film coefficient on the tube side
is 1000 W/m2K.
2. In an oil cooler, 216 kg/h of hot oil enters a thin metal pipe of diameter 25 mm. An equal
mass of cooling water flows through the annular space between the pipe and a larger
concentric pipe; the oil and water moving in opposite directions. The oil enters at 420 K
and is to be cooled to 320 K. If the water enters at 290 K, what length of pipe will be
required? Take coefficients of 1.6 kW/m2 K on the oil side and 3.6 kW/m2 K on the
waterside and 2.0 kJ/kg K for the specific heat of the oil.
3. The heat transfer coefficient  from a hot horizontal pipe to a gas by free convection has
found to be influenced by the specific heat c, thermal conductivity k,density , ,viscosity
, thermal coefficient of expansion , of the gas, pipe diameter D, gravitational constant
g, and the temperature difference t between the surface of the pipe and the main body of
the gas. Establish the form of a dimensionless equation for the heat transfer coefficient.
4. A horizontal shell and tube condenser is to be used to condense saturated ammonia
vapour at 145lbf/in2.abs(Tb=820F). The condenser has 19 steel tubes (1.5 in. OD,1.3 in.
ID) 14 ft long through which cooling water is flowing.The tubes are arranged
hexagonally on 2 in. centres. The latent heat of ammonia at these conditions may be
taken as 500Btu/lb. The cooling water enters at 700F. Determine the capacity of the
condenser for these conditions.
5 54 tonne/h (15 kg/s) of benzene is cooled by passing the stream through the shell side of
a tubular heat exchanger, 1 m ID, fitted with 5 m tubes, 19 mm OD. arranged on a 25 mm
square pitch with 6 mm clearance.If the baffle spacing is 0.25 m (19 baffles), what will
be the pressure drop over the tube bundle? (=0.5mNs/m2).
Reading List:
1 McCabe1,W. L., Smith,J.C. & Harriott, P.(1993). Unit Operations of Chemical
Engineering. Fifth Edition. McGraw Hill Co. Singapore. (pp 309 -396).ISBN 0-07112738-0
2 Coulson4, J.M. ,Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 1, Sixth Edition, Butterworth Heinmann Inc. Oxford.(pp 414 -437).
ISBN 0 7506 4444 3
5
3 Coulson4, J.M. ,Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 3, Sixth Edition, Butterworth Heinmann Inc. Oxford.(pp 125 -216 ).
ISBN 0 7506 44950 X
4 Kern4, D.Q.(1965). Process Heat Transfer. International Edition. McGraw Hill Co.
Singapore. (pp 25-61).ISBN 0-07-085353-3
Week 9 - 11:
Heat Transfer by Radiation.
Objectives: Students should have an understanding of the mechanism of heat transfer by
convection
Description: Concept of radiation, radiation from a black body, radiation from real surfaces,
radiation transfer between black surfaces, radiation transfer between grey surfaces,
radiation from gases. Student will also be assessed on the topics covered so far
through a short Quiz.
Study Question:
1. Distinguish between a black body and a grey surface.
2. What is the temperature of a surface coated with carbon black if the emissive power at a
wavelength of 1.0 x 10~6 m is 1.0 x 109 W/m3? How would this be affected by a +2 per
cent error in the emissive power measurement?
3 A flat-bottomed cylindrical vessel, 2 m in diameter, containing boiling water at 373 K, is
mounted on a cylindrical section of insulating material, 1 m deep and 2 m ID at the base of
which is a radiant heater, also 2 m in diameter, with a surface temperature of 1500 K. If the
vessel base and the heater surfaces may be regarded as black bodies and conduction though
the insulation is negligible, what is the rate of radiant heat transfer to the vessel? How
would this be affected if the insulation were removed so that the system was open to the
surroundings at 290 K?
4
Calculate the radiant heat loss from a furnace through a 2 in diameter peep door when
inside temperature is 17500F and the outside temperature is 700F.Consider the emission due
to a black body.
5
Air leaves a heat exchanger at about 3000C and 1.5atm, and the temperature is measured
using a thermocouple inside a 0.5in. diameter thermowell mounted normal to the air
flow.If the gas velocity is 25ft/s and the pipe wall temperature is 270 0C,what error in
temperature measurement does radiation cause? (Ignore conduction along the axis of the
thermowell)
Reading List:
1 McCabe1,W. L., Smith,J.C. & Harriott, P.(1993). Unit Operations of Chemical
Engineering. Fifth Edition. McGraw Hill Co. Singapore. .(pp397 - 425 ).ISBN 007-112738-0
2 Coulson4, J.M. ,Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 1, Sixth Edition, Butterworth Heinmann Inc. Oxford.(pp
438 -465). ISBN 0 7506 4444 3
3 Coulson4, J.M. ,Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 3, Sixth Edition, Butterworth Heinmann Inc. Oxford.(pp
125 -216). ISBN 0 7506 44950 X
6
4
Kern4, D.Q.(1965). Process Heat Transfer. International Edition. McGraw Hill
Co. Singapore. (pp 62 -84).ISBN 0-07-085353-3
Week 12: Mid Semester Test
Objective: This is to assess the students mastery of the topic covered so far.
Description: Students will be tested on all the topics taken so far. This is to serve as a
preparation for the final examination at the end of the semster
Week 13 : Heat Transfer Equipments.
Objective : Students should be able to desrible the types and basic design calculations of some
heat transfer equptments.
Description: Shell and tube heat exchangers, condensers, boilers and calandrias, evaporators.
Study Question:
1. What is a heat exchanger? List the two broad classification of heat exchanger and two
examples in each class.
2. Explain the term”transfer unit”. What is its relevance in heat transfer?
3. Using Kern's method, design a shell and tube heat exchanger to cool 30 kg/s of butyl
alcohol from 370 to 315 K using treated water as the coolant. The water will enter at 300
K and leave at 315 K.
4 A flow of 1 kg/s of an organic liquid of heat capacity 2.0 kJ/kg K is cooled from 350 to
330 K by a stream of water flowing countercurrently through a double-pipe heat
exchanger. Estimate the effectiveness of the unit if the water enters the exchanger at 290
K and leaves at 320 K.
5 A shell and tube exchanger is used to cool an aqueous stream from 95 to 300C using
coolong water at 200C.If the flow rate of the cooling water is twice that of the process
stream, would a higher overall coefficient be obtained with cooling water in the tubes or
in the shell?
Reading List:
1 McCabe1,W. L., Smith,J.C. & Harriott, P.(1993). Unit Operations of Chemical
Engineering. Fifth Edition. McGraw Hill Co. Singapore. (pp 427 - 461).ISBN 0-07112738-0
2 Coulson4, J.M. ,Richardson, J.F., Backhurst,J.R. & Harker, J.H. (2001). Chemical
Engineering Volume 1, Sixth Edition, Butterworth Heinmann Inc. Oxford. (pp 503 -553).
ISBN 0 7506 4444 3
3 Kern4, D.Q.(1965). Process Heat Transfer. International Edition. McGraw Hill Co.
Singapore. (pp 102 -174).ISBN 0-07-085353-3
Week 14 - 15: Revision/ Tutorial Exercises
Objectives: This is meant to revise the whole course again before examination.
Description: A general overview of the course will be made. Students are expected to seek
explanation on any difficult concept or topic treated during the course.
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LEGEND FOR LIST OF BOOKS:
1
- Available in the University Library
2
- Available in local bookshops
3
- Available on the Web
4
- Personal collection
5
- Departmental library
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