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
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
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.
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
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
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
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
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.
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.