Finned Tube Heat Exchangers
Finned pipe and tubes are used within shell and tube type heat exchangers to enhance the heat transfer efficiency between the inside of the heat exchanger tube or pipe, and the outside. Finned pipes and tubes are commercially available in various sizes and materials. Custom finned tubes and pipes are also available.
Finned Pipe / Tube Design Considerations:
To be able to transfer heat well, the finned tube material must have adequate thermal conductivity. Heat energy transfer is increased by the effective fin area on the tube or pipe. The heat exchanger tube material will thermally expand differently at various temperature, therefore, thermal stresses will be present along the heat exchanger. Additionally, stress will be induced by any high pressure from the applicable fluids. The tube and fin material should be galvanically compatible with all heat exchanger component and fluid for extended service periods under all operating conditions (temperature, pressures, PH). These requirement require careful selection of material: strong, thermally-conductive, and corrosion resistant.
The fin effectiveness in transferring a given quantity of heat is defined by:
Fin efficiency = (Actual Heat Transferred) / (Heat which would be transferred in entire fin area were at base temperature)
Conditions when fins do not help:
Finned tubes / pipes in selected installation will not help thermal transfer. If the convection coeffiecint is large, as it will be with high velocity fluids or boiling liquids, the fins may produce a reduction in heat transfer. This due to the fact that the conduction resistance then represents a larger impediment to the heat flow than the convection resistance.
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