2. Types
Heat Exchanger Types
Heat exchangers are ubiquitous to energy conversion and utilization. They involve heat exchange between two fluids separated by a solid and encompass a wide range of flow configurations.
Concentric-Tube Heat Exchangers
Parallel Flow
Counterflow
Simplest configuration.
Superior performance associated with counter flow.

3. Unfinned-One Fluid Mixed
Types (cont.)
Cross-flow Heat Exchangers
Finned-Both Fluids
Unmixed
Unfinned-One Fluid Mixed
the Other Unmixed
For cross-flow over the tubes, fluid motion, and hence mixing, in the transverse
direction (y) is prevented for the finned tubes, but occurs for the unfinned condition.
Heat exchanger performance is influenced by mixing.

4. Shell-and-Tube Heat Exchangers
Types (cont.)
Shell-and-Tube Heat Exchangers
One Shell Pass and One Tube Pass
Baffles are used to establish a cross-flow and to induce turbulent mixing of the
shell-side fluid, both of which enhance convection.
The number of tube and shell passes may be varied, e.g.:
One Shell Pass,
Two Tube Passes
Two Shell Passes,
Four Tube Passes

5. Compact Heat Exchangers
Types (cont.)
Compact Heat Exchangers
Widely used to achieve large heat rates per unit volume, particularly when
one or both fluids is a gas.
Characterized by large heat transfer surface areas per unit volume, small
flow passages, and laminar flow.
(a) Fin-tube (flat tubes, continuous plate fins)
(b) Fin-tube (circular tubes, continuous plate fins)
(c) Fin-tube (circular tubes, circular fins)
(d) Plate-fin (single pass)
(e) Plate-fin (multipass)

6. Heat Exchangers Double-pipe heat exchanger
Shell and tube heat exchanger
Plate and frame heat exchanger
Spiral heat exchanger
Pipe coil exchanger
Air-cooled heat exchangers

7. Double-Pipe Heat Exchanger
A double-pipe exchanger has a pipe inside a pipe
The outside pipe provides the shell. And the inner pipe provides the tube
The warm and cool fluids can run parallel flow or countercurrent,because it is more efficient
Flow rates are very low in a double-pipe heat exchanger

9. Double-Pipe Heat Exchanger
The chemical processing industry commonly uses hairpin heat exchangers
Hairpins are typically rated at 500psig shellside and 500 psig tubeside
Fins can be added to the internal tube’s external wall to increase heat transfer

10. Double-Pipe Heat Exchanger
Advantages:
Its excellent capacity for thermal expansion
It is easy to install and clean
Its modular design makes it easy to add new sections
Replacement parts are inexpensive and always in supply
Disadvantages
It is not as cost effective as most shell and tube exchangers
it requires special gaskets

11. Shell and Tube Heat Exchangers
The shell and tube heat exchanger is the most common style found in industry
As the tubeside flow enters the exchanger, flow is directed into tubes that run parallel to each other. these tubes run through a shell that has a fluid passing through it
Heat energy is transferred through the tube wall into the cooler fluid
Heat transfer occurs primarily through conduction and convection

14. Shell and Tube Heat Exchanger ---Head
The head can be classified as front-end or rear-end types, the front-end head has five primary designs, the rear-end has eight possible designs

15. Shell and Tube Heat Exchanger ---Shell
In most cases, the shell is designed to withstand the greatest temperature and pressure condition
The shell is the largest single part of the heat exchanger
The shell can be classified as single-pass, double-pass, split flow, double split flow, divided flow, cross-flow

17. Shell and Tube Heat Exchanger ---Tube
Tube can be plain or dinned
Plain tubes are commonly used in fabrication
Finned tube are starting to make an impact, fins can be located externally or internally
Tube materials include brass, carbon, …

19. Shell and Tube Heat Exchanger ---Tube Sheet
Tube sheets are often described as fixed or floating, single or double
Tube sheets have carefully drilled hole, the ends of the tubes in a heat exchanger are fixed by rolling, welding, or both
Double tube sheets are used to prevent tubeside leakage of highly corrosive fluids

20. Shell and Tube Heat Exchanger ---Tube Sheet
Engineering specifications take into account thermal tube expansion
If the tube sheet is welded or bolted to the shell, it is called fixed
If the tube sheet is independently secured to the tub head and is allowed to move freely inside the shell, it is called floating

21. Shell and Tube Heat Exchanger ---Baffle
Baffles provide the framework to support and secure the tubes and prevent vibration
The baffle layout increases or decreases fluid and directs flow at specific points
Tubeside baffles are built into the heads to direct tubeside flow
In multipass exchangers, cost goes up with each pass, provide adequate fluid velocities to prevent fouling and to control heat transfer

23. Shell and Tube Heat Exchanger ---Baffle
Each segmental baffle supports half of the tubes
Baffles are evenly spaced
Segmental baffles may be horizontal or vertical cut
Systems transferring large quantities of suspended solids may use vertical arrangement, which allows liquid and solids to flow around baffles
Horizontal baffles are used in clean service with notches at the bottom to allow liquid drainage on removal from serve

24. Shell and Tube Heat Exchanger ---Baffle
Impingement baffles are used to protect tubing from direct fluid impact
Longitudinal baffles are used inside the shell to split or divide the flow, increase velocity, and provide superior heat transfer capabilities, longitudinal baffles do not extend the entire length of the exchanger since at some point the fluid must flow around it

25. Shell and Tube Heat Exchanger ---Tie Rod
Tie rods and concentric tube spacers keep the baffles in place and evenly spaced
Each hole in the baffle plates is 1/64” larger than the tube’s outside diameter

26. Shell and Tube Heat Exchanger ---Nozzles and Accessory Part
Inlet and outlet nozzles are sized for pressure drop and velocity considerations
Thermowells, pressure indicator connections, safety and relief valves, product drains, vents, block valves and control valves

27. Shell and Tube Heat Exchanger ---Fixed Head
In a fixed head, single pass shell and tube heat exchangers, the tubes are connected to two tube sheets which are firmly attached to the shell
in the multipass Shell and tube heat exchangers, the baffle added to the channel head and the lack of a tube side outlet on the discharge head
Temperature differential is less to 200℃

28. Shell and Tube Heat Exchanger ---Floating Head
One side of the tube bundle is fixed to the channel head, the other side is unsecured
Floating head exchangers, with their high cross-sectional areas(fins), are designed for high temperature differentials and high flow rate, produces the highest heat transfer efficiency

29. Shell and Tube Heat Exchanger ---U-Tube
The tube sheet connects a series of tubes bent in a U shape, the ends of the tubes are secured to the tube sheet
The total number of tubes is limits
Large temperature differentials
Each complete U tube has a single fundamental frequency

30. Plate and Frame Heat Exchanger
It consist of a series of gasketed plates, sandwiched together by two end plates and compression bolts

32. Plate and Frame Heat Exchanger
Easy to disassemble and clean and distribute heat evenly so there are no hot spots
Plates can easily be added or removed
Low fluid resistance time, low fouling, high heat transfer

33. Plate and Frame Heat Exchanger
If gaskets leak, they leak to the outside, and gasket easy to replace
Prevent cross-contamination of products
High turbulence and large pressure drop and small
This device is best suited for vicious or corrosive fluid slurries
High-pressure and high-temperature limitations (2.5MPa and 180℃) for protect internal gasket
Gaskets are easily damaged and may not be compatible with process fluids

34. Spiral Heat Exchanger
Spiral heat exchangers are characterized by a compact concentric design that generates high fluid turbulence
Type 1: spiral flow on both sides
Type 2: spiral flow-cross-flow

36. Pipe Coil Exchanger
Pipe coils are submerged in water or sprayed with water to transfer heat
This type of operation has a low heat transfer coefficient and requires a lot of space

38. Air-Cooled Heat Exchanger
Air-cooled heat exchangers provide plain or dinned tubes connected to an inlet and return header
Air is used as the outside medium to transfer heat away from the tubes
Fans are used in a variety of arrangements to apply forced convection for heat transfer coefficients
Provides a 40℃ temperature differential between the ambient air and the exiting process fluid

40. Air-Cooled Heat Exchanger
simple to construct and cheaper to maintain
Cannot fouling or corrosion
Low operating costs and superior high temperature removal
Limited in use
High outlet fluid temperature and high initial cost of equipment
In cases of loss of containment, they would be fire or explosion

41. Heat Exchangers and Systems ---Parallel and Series Flow
in series flow, the tubeside flow in a multipass heat exchanger is discharged into the tubeside flow of the second exchanger
In parallel flow, the process flow goes through multiple exchangers at the same time

42. Heat Exchangers and Systems ---Cooling Towers
The system consists of a cooling tower, heat exchanger, pump
Cooling water is pumped into the shellside of a heat exchanger and returned (much hotter) to the top of the cooling tower

43. Heat Exchangers and Systems ---Reboilers, Distillation Column
Rebolier---add heat to a liquid that was once boiling until the liquid boils again
Associated with the operation of a distillation column, which is energy of heat balance, reboilers are used to restore this balance by adding additional heat for the separation processes

44. Heat Exchangers and Systems --- Reboilers, Distillation Column
Take kettle reboiler for example, reboilers take suction off of the bottom products and pump them through their system, so column temperatures are controlled at established set-points
Other type of reboilers:
vertical and horizontal thermosyphon reboilers
stab-in reboilers
hot oil jacket reboilers

45. At the End >>
We know the shell and tube heat exchanger consist of Shell side and the tubes inside it
Two fluids of different temperatures are brought into close contact but they are not mixing with each other , one fluid flows through the shell and the other fluid flows through the tubes
The temperature of the two fluids will tend to equalize . The heat are simply exchanged from one fluid to the other and vice versa.
There are three common types of the shell and tubes heat exchanger
1- U-Tube
2- Straight-Tube ( 1-Pass )
3 - Straight-Tube ( 2-Pass )
Shell and Tube Heat Exchanger comes with a lot of different shapes and sizes , It could be large or small or ….

46. Heat Exchangers
A heat exchanger is a device for transferring heat from one fluid to another. There are three main categories: Recuperative, in which the two fluids are at all times separated by a solid wall; Regenerative, in which each fluid transfers heat to or from a matrix of material; Evaporative (direct contact), in which the enthalpy of vaporization of one of the fluids is used to provide a cooling effect.