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How can you choose a suitable plate heat exchanger&spare patrs?(2)
Jan 25, 2019

4 Selection of velocity

 The flow velocity on the main stream line is about 4 to 5 times of the average flow velocity.
Under normal conditions, the selection range of flow velocity between plates is 0.2-1.0m /s,
When the pressure drop is allowable, the maximum value is taken to obtain better heat transfer effect, so as to reduce the heat transfer area.


 5 process selection


When the plate is symmetrical and the flow rate of hot and cold medium is equal, equidistant arrangement should be adopted to make the medium flow direction full counter-current.
When the difference of flow rate between the two sides is large, the side with small flow rate should adopt multi-path layout to improve the flow rate and enhance the heat transfer effect.
In general, in the selection of the process, as far as possible to use one-way (full parallel), so that the equipment in the use of disassembly and maintenance are more convenient. If multiple processes are used, the same number of channels is usually arranged in each process.


6 Choice of flow direction


The heat exchanger is equidistant arrangement, the flow direction of medium can realize full countercurrent, and the maximum average temperature difference can be obtained. When the sides are not equal. Adverse currents and direct currents may occur alternately.


7 The choice of the number of passages


The number of flow passage is affected by the flow velocity between plates, and the selection of flow velocity between plates has a certain range, and is also restricted by the allowable pressure drop.
When the flow rate between plates is constant, the number of passages depends on the size of the flow.


8 Selection of heat exchanger plate and gasket materials


According to the physical and chemical properties of the medium, the main consideration is temperature and corrosion.
The thickness of the plate is 0.6-0.8mm, and 25% reduction is allowed after the corrugated plate is pressed, so the thinest part is 0.45-0.6mm, because of which the corrosion resistant material is selected.
Sealing pad should be resistant to both temperature and corrosion, the hardness should be generally in 65~90 shore hardness, compression permanent deformation of no more than 10%, tensile strength 8MPa, elongation 200%
.


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