Basic concepst in heat exchangers, uses, types and fouling

1. Adlin Miranda Morales
INTD 3355
Prof. Liz Pagan

2. Agenda
 What is a compact heat exchanger?
 Types
 Advantages and limitations
 Cost of heat exchangers
 Fouling
 Security and Environmental aspect
 Design
 Conclusion

3. Basic Definitions
 Heat exchanger: apparatus that has two streams of
fluid that exchange temperatures in order to heat or
cool the system.
 Fouling: type of contamination in the heat exchanger
that can damage its purpose.

4. Description
 Basically this presentation focuses on what are
compact heat exchangers, the various
types, costs, advantages and disadvantages and how
fouling may affect.
 The main option for research was internet and the
library ( books, journals, thesis, etc.)

5. What is a Compact Heat
Exchanger?
 Area density greater than 700 m2/m3 for gas or greater
than 300 m2/m3 when operating in liquid or two-phase
streams.
 Highly efficient
 Reduce volume, weight and cost

6. Types of CHEs
 Plate and frame heat exchangers: (PHE)

7. Plate and Frame Heat Exchanger
 Most common type of PHE
 Consists of plates and gaskets
 Materials: stainless steel, titanium and non-metallic
 Operation limits:
- temperatures from -35°C to 220°C
- pressures up to 25 bar
- flow rate up to 5000 m3/h

8. Brazed Plate Heat Exchanger (PHE)

9. Brazed Plate Heat Exchanger
 Operates at higher pressures than gasketed units
 Materials: stainless steel, copper contained braze
 Operating limits:
- From -195°C to 200°C
- Pressures up to 30 bar
 It is impossible to clean. The only way is by applying
chemicals.

10. Welded Plate Heat Exchanger (PHE)

11. Welded Plate Heat Exchanger
 Plates welded together to increase pressure and
temperature limits
 Materials: stainless steal and nickel based alloys. Can
be made with copper , titanium or graphite
 Operation Limits:
- temperature limits depend on the material
- can tolerate pressures in excess of 60 bar

12. Spiral Heat Exchanger (SHE)

13. Spiral Heat Exchanger (SHE)
 Two long strips of plate wrapped to form concentric
spirals
 Materials: carbon steel, stainless steel and titanium
 Operation limits:
- Temperatures up to 400°C (depends on gasketed
materials)
- Pressures up to 25 bar

14. Plate Fin Heat Exchanger (PFHE)

15. Plate Fin Heat Exchanger (PFHE)
 High area density and handles several streams
 Materials: aluminum, corrosion and heat resistant
alloys, and stainless steel (available in titanium)
 Operation limits:
- Temperature limits depend on the material
- cryogenic temperature up to 100°C (aluminum)
- stainless steel up to 650°C
- Pressures up to 100 bar for aluminum and 90 bar for
stainless steel

16. Printed-circuit heat exchangers
(PCHE)

17. Printed-circuit heat exchangers
(PCHE)
 Flexibility of design and high strength offered by
techniques of construction
 Materials: Stainless steel 316L, alloys, nickel and
titanium.
 Operating limits:
- temperature ranges from -200°C to 900°C
- pressures up to 400 bar

18. Compact Shell-and-Tube Heat
Exchanger
To increase surface area, this equipment has a large
number of small diameter tubes

19. Other Types of CHE
 Compact types retaining a shell
 APV Paratube Heat Exchanger
 Fluidized Bed Heat Exchanger
 Twisted Tube Heat Exchanger

20. Advantages and Limitations
 Improved energy efficiency
- Closer approach temperatures allows greater energy
transfer.
 Smaller volume and weight
 Higher efficiency
 Lower cost
 Multi-stream and multi-pass configurations
 Tighter temperature control
 Power savings
 Improved safety

21. Limitations
 Lack of industrial awareness
Companies remain aware of technology of CHE
 Limited choice
Particularly for high-pressure
 Conservatism in the user industries
Process industries are reluctant to adopt what
they may seen either as new technologies.
 Susceptibility to fouling
Perception that small passages are likely to foul.

22. Cost of compact heat exchangers
 Compact heat exchanger tend to be cheaper especially
when their total installed cost is considered.
 In some cases the materials used to manufacture is
expensive, but when we consider the cost of unit plus
the installation, the cost is less than equivalent shell
and tube.

23. Cost of compact heat exchangers

24. Fouling
 Crystallization or precipitation
Solutes in the fluid is precipitated and crystals are formed
 Particulate fouling or silting
Solid particles are deposited on the heat transfer surface
 Biological fouling
Deposition and growth of organism on surfaces
 Corrosion fouling
Carrying of corrosion products from other part of the
system being left on the heat transfer area surface
 Chemical reaction fouling
Arises from reactions between constituents in the process
fluids
 Freezing or solidification fouling
Occurs when the temperature of a fluid passing through a
heat exchanger becomes too low

25. Security Aspects
 Fouling:
- Use of non-fouling fluids wherever possible is of
course recommended, for example clean air or
gases, light carbons and refrigerants.
- In open systems, check the possible application of
self-cleaning strainers, and the installation of systems
to dose with biocides, scale inhibitors, etc., to control
fouling.
- Use self-cleaning filter if possible
- Consider chemical cleaning. If this is undertaken, the
system must be designed to allow the introduction and
complete removal of cleaning fluids.

26. Corrosion:
 In some CHEs, the wall thicknesses are less than in a
shell-and-tube heat exchanger, so corrosion rates and
allowances need to be accessed carefully
 Although CHEs are often made from more corrosion-
resistant materials than the shell-and-tube units, other
corrosion mechanisms such as cracking may
occur, and the compatibility of the material with the
fluids in the CHE should be checked.

27. Design
 Analysis based on ε and Ntu method
 Convection and friction coefficients have been
determined by Kays and London.
 Some data of design can be supplied by
manufacturers.
 Results for heat transfer and friction factors for
circular tube- circular fin and for circular tubes –
continuous fin.

28.  
VA fr m m
G V max
A ff A ff A fr
A ff área mínima flujo libre
A fr área frontal
2 /3
jH St Pr
St h /Gc p
G V max
Re GD h /

29. 2 /3
jH St Pr
 
VA fr m m
G V max
A ff A ff A fr St h /Gc p
A ff área mínima flujo libre
G V max
A fr área frontal
Re GD h /

30. Environmental Aspects
 Energy conservation and environmental
considerations are the driving forces behind changes
aimed at reducing both chemical and thermal waste.
 More efficient use of energy and raw materials
 Recovery of heats of reaction
 High intensity mixing, enhancing process selectivity
 Minimum risk of runaway reactions
 Smaller and cheaper plant
 Ability to handle high-pressure reactions

31. Conclusion
 Compact heat exchangers are available in a wide
variety of configurations to suit most processes heat
transfer requirements.
 The advantages of CHEs, and associated heat transfer
enhancement techniques, extend far beyond energy
efficiency.
 Lower capital cost, reduced plant size, and increased
safety are typical of the benefits arising from the use of
CHEs.
 Compact heat exchangers can replace some normal
size heat exchangers bringing advantages and
performance.

32. Conclusion
 This research took a lot of time, since the specific
details of a theme like this take time to search.
 Even though it took time, I really enjoyed making this
presentation.

33. References
 ADVANCES IN COMPACT HEAT EXCHANGERS. (n.d.). Retrieved March 5, 2009, from
http://www.rtedwards.com/books/164/index.html
 Al-Qahtani, Abdullah Mushabbab Zuhair, M.S., 2008, Design and operate a fouling
monitoring device to study fouling at twisted tube. King Fahd University of Petroleum
and Minerals (Saudi Arabia), 171 pages; AAT 1456206.
 An Assessment of the Performance and Requirements for quot;Adiabaticquot; Engines.
(1988, May 27). Science Magazine, 240, 1157-1162. Retrieved March 5, 2009, from
http://library.uprm.edu:2132/cgi/content/abstract/sci;240/4856/1157?maxtoshow=&HITS
=10&hits=10&RESULTFORMAT=&fulltext=heat+exchangers&searchid=1&FIRSTINDEX=1
0&resourcetype=HWCIT
 Bell, L. E. (2008, September 12). Cooling, Heating, Generating Power, and Recovering
Waste Heat with Thermoelectric Systems . Science Magazine, 321, 1457-1461. Retrieved
March 5, 2009, from
http://library.uprm.edu:2132/cgi/content/abstract/sci;321/5895/1457?maxtoshow=&HITS
=10&hits=10&RESULTFORMAT=&fulltext=heat+exchangers&searchid=1&FIRSTINDEX=0
&resourcetype=HWCIT

34. References
 Compact Heat Exchangers. (n.d.). Retrieved March 5, 2009, from
http://www.eca.gov.uk/etl/find/_85.htm
 Designing Shell and Tube Heat Exchangers. (n.d.). Retrieved March
5, 2009, from http://www.cheresources.com/designexzz.shtml
 Energy Savers: Heat Exchangers for Solar Water Heating Systems.
(n.d.). Retrieved March 5, 2009, from
http://www.energysavers.gov/your_home/water_heating/index.cfm/m
ytopic=12930
 Enhanced, Compact and Ultra-Compact Heat Exchangers:
Science, Engineering and Technology. (n.d.). Retrieved March
5, 2009, from http://services.bepress.com/eci/heatexchangerfall2005/

35. References
 Hawkins, G. A. (1954, December 10). Heat Transmission. Science Magazine, 532.
 Heat Exchangers - Shell & Tube, Plate, Air-Cooled : API Heat Transfer. (n.d.). Retrieved
March 5, 2009, from http://www.apiheattransfer.com/
 Heat Exchangers for the HVAC Industry. (n.d.). Retrieved March 5, 2009, from
http://www.heatexchangersonline.com/
 Heat Exchangers. (n.d.). Retrieved March 5, 2009, from
http://www.flatplate.com/?gclid=CNbbnaC1pZoCFRKIxwodJDnU8w
 Heat Transfer Engineering. (1979, January 8). Heat Transfer Engineering, 1, pp. 2.
 JM Heat Exchangers - Heat Transfer Specialists. Shell & Tube Exchangers, Fin
Coils, Calorifiers, Plate Heat Exchangers, Charge Air Coolers, Fin Fan Exchangers. (n.d.).
Retrieved March 5, 2009, from http://www.jmheatexchangers.com/

36. References
 Macro Power from Micro Machinery. (1997, May 23). Science Magazine, 276, 1211.
Retrieved March 5, 2009, from
http://library.uprm.edu:2132/cgi/content/summary/sci;276/5316/1211?maxtoshow=&HITS
=10&hits=10&RESULTFORMAT=&fulltext=heat+exchangers&searchid=1&FIRSTINDEX=0
&resourcetype=HWCIT
 Veronica, Daniel Alexander, Ph.D., 2008, Detecting heat exchanger fouling automatically
with an embedded data-driven agent using expert signature maps. University of Colorado
at Boulder, 245 pages; AAT 3303899
 (2004). Compact Multifunctional Heat Exchangers: A Pathway to Process Intensification.
Grenoble, France: CEA-Grenoble.
 (2001). Handbook of Heating, Ventilation, and Air Conditioning. Boca Raton: CRC Press
LLC.
 (2003). Heat Transfer in Single and Multiphase Systems. Boca Raton: CRC Press LLC.
 (2000). The CRC Handbook of Thermal Engineering. Boca Raton: CRC Press LLC.