Sunday, April 24, 2011

Advantages and disadvantages of plate heat exchangers

  • Compactness- The units in a plate heat exchanger occupy less floor space and floor loading by having a large surface area that is formed from a small volume. This in turn produces a high overall heat transfer coefficient due to the heat transfer associated with the narrow passages and corrugated surfaces.
  • Flexibility- Changes can be made to heat exchanger performance by utilizing a wide range of fluids and conditions that can be modified to adapt to the various design specifications. These specifications can be matched with different plate corrugations.
  • Low Fabrication Costs- Welded plates are relatively more expensive than pressed plates. Plate heat exchangers are made from pressed plates, which allow greater resistance to corrosion and chemical reactions.
  • Ease of Cleaning- The heat exchanger can be easily dismantled for inspection and cleaning (especially in food processing) and the plates are also easily replaceable as they can be removed and replaced individually.
  • Temperature Control- The plate heat exchanger can operate with relatively small temperature differences. This is an advantage when high temperatures must be avoided. Local overheating and possibility of stagnant zones can also be reduced by the form of the flow passage.

  • The main weakness of the plate and frame heat exchanger is the necessity for the long gaskets which holds the plates together. Although these gaskets are seen as drawback, plate-and-frame heat exchangers have been successfully run at high temperatures and pressures.
  • There is a potential for leakage. The leaks that occur are sent to the atmosphere and not between process streams.
  • The pressure drop that occurs through a plate heat exchanger is relatively high and the running costs and capital of the pumping system should be considered.
  • When loss of containment or loss of pressure occurs, it can take a long time to clean and reinitialise this type of exchanger as hundreds of plates are common in larger builds.
  • The narrow spacing between plates can become blocked by particulate contaminants in the fluid, for example oxide and sludge particles found in central heating systems.
  • For the reason above most manufacturers will only guarantee their units for 12 months, furthermore replacement plate and gasket sets can be as much as the plate to buy initially.
source: wikipedia
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