Compact heat exchangers

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Compact heat exchangers

  1. 1. HARSHAD KANGANE.M.E. Thermal.Sem- II.
  2. 2. Agenda What is a compact heat exchanger? Types Advantages and limitations Cost of heat exchangers Care to be taken Environmental Aspects Conclusion Reference
  3. 3. Basic Definitions A heat exchanger is a device built for efficient heattransfer from one medium to another, whether themedia are separated by a solid wall so that they nevermix, or the media are in direct contact.
  4. 4. What is a Compact HeatExchanger? HT Area density greater than 700 m2/m3 for gas orgreater than 300 m2/m3 when operating in liquid ortwo-phase streams. Highly efficient Reduce volume, weight and cost
  5. 5. Types of CHEs Plate and frame heat exchangers: (PHE) PHE Countercurrent.mp4
  6. 6. 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
  7. 7. Brazed Plate Heat Exchanger (PHE)
  8. 8. 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 applyingchemicals.
  9. 9. Welded Plate Heat Exchanger (PHE)
  10. 10. Welded Plate Heat Exchanger Plates welded together to increase pressure andtemperature limits Materials: stainless steal and nickel based alloys. Canbe made with copper , titanium or graphite Operation Limits:- temperature limits depend on the material- can tolerate pressures in excess of 60 bar
  11. 11. Spiral Heat Exchanger (SHE)Spiral HX for Liquid-Liquid.mp4
  12. 12. Spiral Heat Exchanger (SHE) Two long strips of plate wrapped to form concentricspirals Materials: carbon steel, stainless steel and titanium Operation limits:- Temperatures up to 400°C (depends on gasketedmaterials)- Pressures up to 25 bar
  13. 13. Plate Fin Heat Exchanger (PFHE)
  14. 14. Plate Fin Heat Exchanger (PFHE) High area density and handles several streams Materials: aluminum, corrosion and heat resistantalloys, 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 forstainless steel
  15. 15. Printed-circuit heat exchangers(PCHE)
  16. 16. Printed-circuit heat exchangers(PCHE) Flexibility of design and high strength offered bytechniques of construction Materials: Stainless steel 316, alloys, nickel andtitanium. The etched plates are stacked and diffusion bondedtogether to make the core of Hx Operating limits:- temperature ranges from -200°C to 900°C- pressures up to 600 bar
  17. 17. Compact Shell-and-Tube HeatExchangerTo increase surface area, this equipment has a largenumber of small diameter tubes
  18. 18. Advantages Improved energy efficiency- Closer approach temperatures allows greater energytransfer. Smaller volume and weight Higher efficiency Lower cost Multi-stream and multi-pass configurations Tighter temperature control Power savings Improved safety
  19. 19. Limitations Lack of industrial awarenessCompanies remain aware of technology of CHE Limited choiceParticularly for high-pressure Conservatism in the user industriesProcess industries are reluctant to adopt what theymay seen either as new technologies. Susceptibility to foulingPerception that small passages are likely to foul. Expensive. Blockages can occurs very easily.
  20. 20. Cost of compact heat exchangers Compact heat exchanger tend to be cheaper especiallywhen their total installed cost is considered. In some cases the materials used to manufacture isexpensive, but when we consider the cost of unit plusthe installation, the cost is less than equivalent shelland tube.
  21. 21. Cost of compact heat exchangers
  22. 22. Care to be taken Fouling:- Use of non-fouling fluids wherever possible is ofcourse recommended, for example clean air orgases, light carbons and refrigerants.- In open systems, check the possible application ofself-cleaning strainers, and the installation of systemsto dose with biocides, scale inhibitors, etc., to controlfouling.- Use self-cleaning filter if possible- Consider chemical cleaning. If this is undertaken, thesystem must be designed to allow the introduction andcomplete removal of cleaning fluids.
  23. 23. Corrosion: In some CHEs, the wall thicknesses are less than in ashell-and-tube heat exchanger, so corrosion rates andallowances need to be accessed carefully Although CHEs are often made from more corrosion-resistant materials than the shell-and-tube units, othercorrosion mechanisms such as cracking mayoccur, and the compatibility of the material with thefluids in the CHE should be checked.
  24. 24. Environmental Aspects Energy conservation and environmentalconsiderations are the driving forces behind changesaimed at reducing both chemical and thermal waste. More efficient use of energy and raw materials Smaller and cheaper plant Ability to handle high-pressure reactions
  25. 25. Application Automobile Marine Aerospace, Aircraft Criogenic systems Refrigeration.Manufacturers in the Market Alfa Laval Gea Ecoflex Sondex Swep Tranter Funke
  26. 26. Conclusion Compact heat exchangers are available in a widevariety of configurations to suit most processes heattransfer requirements. The advantages of CHEs, and associated heat transferenhancement techniques, extend far beyond energyefficiency. Lower capital cost, reduced plant size, and increasedsafety are typical of the benefits arising from the use ofCHEs. Compact heat exchangers can replace some normalsize heat exchangers bringing advantages andperformance.
  27. 27. References ADVANCES IN COMPACT HEAT EXCHANGERS.(n.d.). Retrieved March 5, 2009, fromhttp://www.rtedwards.com/books/164/index.html http://www.chemkb.com/equipments/heat-exchangers/printed-circuit-heat-exchanger-pche http://www.alfalaval.com http://www.wikipedia.com

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