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We have discussed in detail externally finned tubes, internally finned tubes and annuli in this book. Following conclusions may be drawn:
Wavy fins or some form of interrupted strip fins are used for gases.
Analytical or numerical models are available to predict the heat transfer performance of high finned tube banks.
Power law empirical correlations for plain fins have been developed.
No general widely applicable correlation is available, although some correlations do predict data.
Row effect of in-line and staggered tube arrangements makes the performance more complicated.
In-line layouts have lower heat transfer performance than that by staggered tube layout.
Both individually finned tube and plate fin-and-tube geometries are used for enhancement. Cost consideration plays a key role in decision-making.
Higher performance can be obtained from oval or flat tubes.
Hydrophilic coatings are used.
Gas-side fouling limits the permissible enhanced fin geometry.
Internally finned tubes and annuli are used to enhance tube-side heat transfer; many numerical analysis and empirically developed correlations are available.