Allocation principles
In shell and tube
Heat Exchangers with no phase change fluid transfer, the cold and hot fluid flow paths can be selected according to the following principles.
01
Unclean or easily decomposed scaling materials should flow through the side that is easy to clean. For straight tube bundles, it is generally advisable to go inside the tube so that the fluid velocity can be easily controlled, while the higher fluid flow rate allowed inside the tube also reduces scaling; when the tube bundle can be removed for cleaning, it can also go outside the tube.
02
Corrosive fluids should be taken inside the tube to avoid corrosion of the tube bundle and the shell at the same time.
03
Very high temperature (or very low) materials should go inside the tube to reduce the loss of heat (or cold), but also to reduce the need for special metals, reducing the cost of heat exchangers; but the fluid required to be cooled should go to the shell process, to facilitate heat dissipation.
04
High pressure materials should go to the tube process, so as to avoid shell pressure, thus reducing costs.
05
Allow the pressure drop is very low fluid should take the tube process, the pressure drop is the same, the tube process can get a higher heat transfer coefficient.
06
Steam should go to the shell process, because it is relatively clean, the heat transfer coefficient and the flow rate is small and easy to discharge condensate.
07
Fluids with high viscosity are generally suitable for the shell process, where turbulence can be achieved at lower flow rates. If turbulence cannot be achieved in the shell process, then the tube process is preferred and the calculated heat transfer coefficient for the tube process is more accurate.
08
Fluids with low flow rates are preferred to go through the shell process, where turbulence can be achieved at lower flow rates and the most economical design can usually be obtained.
09
In the case of large temperature differences between the two fluids, for rigid structures of heat exchangers, it is advisable to pass the liquid with a large heat transfer coefficient into the shell process to reduce thermal stress.
10
Fluids that require higher flow rates to increase their heat transfer coefficients should be routed through a tube, as the cross-sectional area of the tube is smaller and multiple tube passes can easily be used.
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