1. HEAT TRANSFER, HEAT
EXCHANGERS, CONDENSORS AND
REBOILERS, AIR COOLERS
Reyad Awwad Shawabkeh
Associate Professor of Chemical Engineering
King Fahd University of Petroleum & Minerals
Dhahran, 31261
Kingdom of Saudi Arabia

2. Contents
 HEAT TRANSFER LAW APPLIED TO HEAT EXCHANGERS 2
 Heat Transfer by Conduction 3
 The Heat Conduction Equation 9
 Heat Transfer by Convection 12
 Forced Convection 12
 Natural Convection 14
 Heat Transfer by Radiation 15
 Overall heat transfer coefficient 18
 Problems 22
 DESIGN STANDARDS FOR TUBULAR HEAT EXCHANGERS 23
 Size numbering and naming 23
 Sizing and dimension 27
 Tube-side design 32
 Shell-side design 33
 Baffle type and spacing 33
 General design consideration 35
 THERMAL AND HYDRAULIC HEAT EXCHANGER DESIGN 37
 Design of Single phase heat exchanger 37
 Kern’s Method 45
 Bell’s method 49
 Pressure drop inside the shell and tube heat exchanger 57
 Design of Condensers 65
 Design of Reboiler and Vaporizers 72
 Design of Air Coolers9 85
 MECHANICAL DESIGN FOR HEAT EXCHANGERS10 88
 Design Loadings 88
 Tube-Sheet Design as Per TEMA Standards 90
 Design of Cylindrical shell, end closures and forced head 91
 References 95

3. HEAT TRANSFER LAW APPLIED TO HEAT EXCHANGERS

4. Heat Transfer by Conduction
W/m2 W/m.K

5. Thermal Conductivity of solids

6. Thermal Conductivity of liquids

7. Thermal conductivity of gases

8. Example
Calculate the heat flux within a copper rod that
heated in one of its ends to a temperature of 100 oC
while the other end is kept at 25 oC. The rode length
is 10 m and diameter is 1 cm.

9. Example
An industrial freezer is designed to operate with an internal air
temperature of -20 oC when external air temperature is 25 oC. The walls
of the freezer are composite construction, comprising of an inner layer of
plastic with thickness of 3 mm and has a thermal conductivity of 1 W/m.K.
The outer layer of the freezer is stainless steel with 1 mm thickness and
has a thermal conductivity of 16 W/m.K. An insulation layer is placed
between the inner and outer layer with a thermal conductivity of 15
W/m.K. what will be the thickness of this insulation material that allows a
heat transfer of 15 W/m2 to pass through the three layers, assuming the
area normal to heat flow is 1 m2?

10. The Heat Conduction Equation
Rate of heat
generation
inside control
volume
Rate of energy
storage inside
control volume
Rate of heat
conduction
into control
volume
+ =
Rate of heat
conduction
out of control
volume
+

11. The Heat Conduction Equation

12. Heat Transfer by Convection

13. Reynolds and Prandtl Numbers
Values of Prandtl number for different liquids and gases
Re < 2100 Laminar flow
Re > 2100 Turbulent flow

14. Flow through a single smooth cylinder
This correlation is valid over the ranges 10 < Rel < 107 and 0.6 < Pr < 1000 where

15. Flow over a Flat Plate
Re < 5000 Laminar flow
Re > 5000 Turbulent flow

16. Natural Convection

17. Heat Transfer by Radiation
q = ε σ (Th4 - Tc4) Ac
Th = hot body absolute temperature (K)
Tc = cold surroundings absolute temperature (K)
Ac = area of the object (m2)
σ = 5.6703 10-8 (W/m2K4)
The Stefan-Boltzmann Constant

18. Emissivity coefficient for several selected material
Surface Material
Emissivity Coefficient
- ε -
Aluminum Commercial sheet 0.09
Aluminum Foil 0.04
Aluminum Commercial Sheet 0.09
Brass Dull Plate 0.22
Brass Rolled Plate Natural Surface 0.06
Cadmium 0.02
Carbon, not oxidized 0.81
Carbon filament 0.77
Concrete, rough 0.94
Granite 0.45
Iron polished 0.14 - 0.38
Porcelain glazed 0.93
Quartz glass 0.93
Water 0.95 - 0.963
Zink Tarnished 0.25

19. Overall heat transfer coefficient
For a wall
For cylindrical
geometry

20. Typical value for overall heat transfer coefficient
Shell and Tube
Heat Exchangers
Hot Fluid Cold Fluid U [W/m2C]
Heat Exchangers Water Water 800 - 1500
Organic solvents Organic Solvents 100 - 300
Light oils Light oils 100 - 400
Heavy oils Heavy oils 50 - 300
Reduced crude Flashed crude 35 - 150
Regenerated DEA Foul DEA 450 - 650
Gases (p = atm) Gases (p = atm) 5 - 35
Gases (p = 200 bar) Gases (p = 200 bar) 100 - 300
Coolers Organic solvents Water 250 - 750
Light oils Water 350 - 700
Heavy oils Water 60 - 300
Reduced crude Water 75 - 200
Gases (p = 200 bar) Water 150 - 400
Organic solvents Brine 150 - 500
Water Brine 600 - 1200

21. Heat Exchangers Hot Fluid Cold Fluid U [W/m2C]
Heaters Steam Water 1500 - 4000
Steam Organic solvents 500 - 1000
Steam Light oils 300 - 900
Steam Heavy oils 60 - 450
Steam Gases 30 - 300
Heat Transfer (hot) Oil Heavy oils 50 - 300
Flue gases Steam 30 - 100
Flue gases Hydrocarbon vapors 30 -100
Condensers Aqueous vapors Water 1000 - 1500
Organic vapors Water 700 - 1000
Refinery hydrocarbons Water 400 - 550
Vapors with some non
condensable
Water 500 - 700
Vacuum condensers Water 200 - 500
Vaporizers Steam Aqueous solutions 1000 - 1500
Steam Light organics 900 - 1200
Steam Heavy organics 600 - 900
Heat Transfer (hot) oil Refinery hydrocarbons 250 - 550

22. DESIGN STANDARDS FOR TUBULAR HEAT
EXCHANGERS
• Size of heat exchanger is represented by the shell inside
diameter or bundle diameter and the tube length
• Type and naming of the heat exchanger is designed by
three letters single pass shell
The first one describes the stationary head type
The second one refers to the shell type
The third letter shows the rear head type
TYPE AES refers to Split-ring floating head exchanger with
removable channel and cover.

23. Heat exchanger nomenclatures

24. The standard nomenclature for shell and tube heat exchanger
1. Stationary Head-Channel
2. Stationary Head-Bonnet
3. Stationary Head Flange-Channel or
Bonnet
4. Channel Cover
5. Stationary Head Nozzle
6. Stationary Tube sheet
7. Tubes
8. Shell
9. Shell Cover
10. Shell Flange-Stationary Head End
11. Shell Flange-Rear Head End
12. Shell Node
13. Shell Cover Flange
14. Expansion Joint
15. Floating Tube sheet
16. Floating Head Cover
17. Floating Head Cover Flange
18. Floating Head Backing Device
19. Split Shear Ring
20. Slip-on Backing Flange
21. Floating Head Cover-External
22. Floating Tube sheet Skirt
23. Packing Box
24. Packing
25. Packing Gland
26. Lantern Ring
27. Tie-rods and Spacers
28. Support Plates
29. Impingement Plate
30. Longitudinal Baffle
31. Pass Partition
32. Vent Connection
33. Drain Connection
34. Instrument Connection
35. Support Saddle
36. Lifting Lug
37. Support Bracket
38. Weir
39. Liquid Level Connection
40. Floating Head Support

25. Removable cover, one pass, and floating head heat exchanger
Removable cover, one pass, and outside packed floating head heat exchanger

26. Channel integral removable cover, one pass, and outside packed
floating head heat exchanger

27. Removable kettle type reboiler with pull through floating head

28. Gauge
(B.W.G.)
(inches)
(B.W.G.)
(mm)
Gauge
(B.W.G.)
(inches)
(B.W.G.)
(mm)
00000 (5/0) 0.500 12.7 23 0.025 0.6
0000 (4/0) 0.454 11.5 24 0.022 0.6
000 (3/0) 0.425 10.8 25 0.020 0.5
00 (2/0) 0.380 9.7 26 0.018 0.5
0 0.340 8.6 27 0.016 0.4
1 0.300 7.6 28 0.014 0.4
2 0.284 7.2 29 0.013 0.3
3 0.259 6.6 30 0.012 0.3
4 0.238 6.0 31 0.010 0.3
5 0.220 5.6 32 0.009 0.2
6 0.203 5.2 33 0.008 0.2
7 0.180 4.6 34 0.007 0.2
8 0.165 4.2 35 0.005 0.1
9 0.148 3.8 36 0.004 0.1
10 0.134 3.4 25 0.020 0.5
11 0.120 3.0 26 0.018 0.5
12 0.109 2.8 27 0.016 0.4
13 0.095 2.4 28 0.014 0.4
14 0.083 2.1 29 0.013 0.3
15 0.072 1.8 30 0.012 0.3
16 0.065 1.7 31 0.010 0.3
17 0.058 1.5 32 0.009 0.2
18 0.049 1.2 33 0.008 0.2
19 0.042 1.1 34 0.007 0.2
20 0.035 0.9 35 0.005 0.1
21 0.032 0.8 36 0.004 0.1
22 0.028 0.7
Tube sizing: Birmingham Wire Gage

29. Tube sizing: Birmingham Wire Gage

30. Tube-side design
Arrangement of tubes inside the heat exchanger

31. Shell-side design
types of shell passes(a) one-pass shell for E-type,
(b) split flow of G-type,
(c) divided flow of J-type,
(d) two-pass shell with longitudinal baffle of F-type
(e) double split flow of H-type.

32. Shell-side design
Shell thickness for different diameters and material of constructions

33. Baffle type and spacing

34. General design consideration
Factor Tube-side Shell-side
Corrosion More corrosive fluid Less corrosive fluids
Fouling Fluids with high fouling
and scaling
Low fouling and scaling
Fluid temperature High temperature Low temperature
Operating pressure Fluids with low pressure
drop
Fluids with high pressure
drop
Viscosity Less viscous fluid More viscous fluid
Stream flow rate High flow rate Low flow rate

35. THERMAL AND HYDRAULIC HEAT EXCHANGER
DESIGN
Design of Single phase heat exchanger
Design of Condensers
Design of Reboiler and Vaporizers
Design of Air Coolers

36. Design of Single phase heat exchanger

37. Typical values for fouling factor coefficients

38. Temperature profile for different types of
heat exchangers

39. For counter current
For co-current

40. one shell pass; two or more even tube 'passes

41. two shell passes; four or multiples of four tube passes
divided-flow shell; two or more even-tube passes

42. split flow shell, 2 tube pass
cross flow heat exchanger

43. Shell-side heat transfer coefficient

45. Shell diameter

47. Bundle diameter clearance

48. Tube-side heat transfer coefficient

49. Tube-side heat transfer factor

50. Shell and Tube design procedure
• Kern’s Method
• Bell’s method
This method is designed to predict the local heat transfer coefficient and
pressure drop by incorporating the effect of leak and by-passing inside the
shell and also can be used to investigate the effect of constructional
tolerance and the use of seal strip
This method was based on experimental work on commercial exchangers
with standard tolerances and will give a reasonably satisfactory prediction of
the heat-transfer coefficient for standard designs.

51. Kern’s Method

52. Bell’s method

56. Figure 34 Baffle cut geometry

59. Pressure drop inside the shell

60. Pressure drop inside the tubes

61. Design of Condensers
Direct contact cooler
• For reactor off-gas quenching
• Vacuum condenser
• De-superheating
• Humidification
• Cooling towers

62. Condensation outside horizontal tubes
For turbulent flow,
For Laminar flow

63. Condensation inside horizontal tubes
stratified flow
annular flow

64. Design of Reboiler and Vaporizers
Forced-circulation reboiler
Thermosyphon reboiler
Kettle reboiler
• Suitable to carry viscous and heavy fluids.
• Pumping cost is high
• The most economical type where there is no need for
pumping of the fluid
• It is not suitable for viscous fluid or high vacuum
operation
• Need to have a hydrostatic head of the fluid
• It has the lower heat transfer coefficient than the other
types for not having liquid circulation
• Used for fouling materials and vacuum operation with a
rate of vaporization up to 80% of the feed

65. Boiling heat transfer and pool boiling
Nucleate pool boiling
Critical heat flux
Film boiling

66. Nucleate
boiling heat
transfer
coefficient

67. Critical flux
heat transfer
coefficient
Film boiling
heat transfer
coefficient

68. Convection boiling
Effective heat transfer coefficient encounter the
effect of both convective and nucleate boiling

71. Design of air cooler

73. Mechanical Design for HE
A typical sequence of mechanical design procedures is summarized
by the flowing steps
• Identify applied loadings.
• Determine applicable codes and standards.
• Select materials of construction (except for tube material, which
is selected during the thermal design stage).
• Compute pressure part thickness and reinforcements.
• Select appropriate welding details.
• Establish that no thermohydraulic conditions are violated.
• Design nonpressure parts.
• Design supports.
• Select appropriate inspection procedure

74. Design loading