The document describes a double pipe heat exchanger and provides classifications of heat exchangers. A double pipe heat exchanger consists of two concentric pipes and connecting tees to transfer thermal energy between two fluids. Heat exchangers can be classified based on their heat transfer mechanism, construction type, flow arrangement, number of passes, and operating temperatures and pressures. Common types include plate, tubular, extended surface, and phase change heat exchangers.

1. Double pipe heat exchanger
• Two sets of concentric pipes, two connecting tees, and a
return head and a return bend.
• A device whose purpose is the transfer of thermal
energy between two fluids.
• Heat Exchanger-HX
• Common applications: Boilers, Coolers, Condensers,
Evaporators.
• Common design consists of tow fluids separated by a
conducting medium.

2. Classification
 Heat transfer mechanism
 Degree of surface compactness
 Heat transfer type
 Flow arrangement
 Number of passes
 Construction

3. Classification
 Direct contact type: Cooling towers, Spray towers
 Indirect contact type
Cooling tower Spray tower

4. Classification
 Single Pass arrangement
 Multiple pass arrangement

5. Classification
 The choice of a particular flow arrangement depends
upon the required heat exchanger effectiveness, fluid
flow paths, allowable thermal stresses, temperature
levels and other design criteria.
 Heat exchangers may be classified according to their
flow arrangement.
• Parallel-flow
• Counter-flow
• Cross-flow
• Divided-flow
• Split-flow

6. Classification

7. Classification
 The heat exchangers classify based on geometry of
construction are,
• Plate Heat Exchangers
• Extended surface Heat Exchangers
• Tubular Heat Exchangers

8. Classification
 Plate Heat Exchanger
• Limited to below 25 bar and 2500C
• Plate heat exchangers have three main types :
gasketed ,spiral and lamella heat exchangers.
• The most common of the plate-type heat
exchangers is the gasketed plate heat exchanger

9. Classification
Plate type heat exchanger

10. Classification
Spiral heat exchanger

11. Classification

12. Classification
 Plate Heat Exchanger
 Aadvantages
• Plate heat exchangers yield heat transfer rates
three to five times greater than other types of heat
exchangers.
• The design of the plate heat exchanger allows to
add or remove plates to optimize performance, or
to allow for cleaning, service, or maintenance.
• Plate exchangers offer the highest efficiency
mechanism for heat transfer available in industry.

13. Classification
 Plate Heat Exchanger
 Disadvantages
• Plate exchangers are limited when high pressures,
high temperatures, or aggressive fluids are present.
• Because of this problem these type of heat
exchangers have only been used in small, low
pressure applications such as on oil coolers for
engines.

14. Classification
 Extended surface heat exchangers
• Plate fin heat exchanger
• Tube fin heat exchanger
Tube fin exchanger Plate fin exchanger

15. Classification

16. Classification

17. Classification
 Tubular heat exchanger
• Material and design development
• Widely used
• No limit to range of temperatures and pressures
• Two types
1. Double pipe heat exchanger
2. Shell and tube heat exchanger

18. Classification
 Double pipe heat exchanger
They consist of one pipe concentrically located inside a
second larger pipe.
Double pipe exchanger

19. Classification
 Phase change heat exchangers
• Condensers(water cooled, air cooled)
• Reboilers
• Evaporators
Induced draft
Forced draft
Air cooled condenser

20. Classification
 Phase change heat exchangers
Water cooled condenser

21. Classification
Area density: Ratio of heat transfer area to the volume
of heat exchanger
 Compact Heat exchanger
• Area density greater than 700 m2/m3 or 213 ft2/ft3
or hydraulic diameter ≤ ¼ inch for gas stream.
• Area density greater than 400 m2/m3 or 122 ft2/ft3
for liquid stream).
 Non-compact Heat exchanger
• Area density less than 700 m2/m3 for gas stream.
• Area density less than 400 m2/m3 for liquid stream.

22. Classification

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