1.6
1.4
No Condensation
1.2
1.0
Tfb = 0 C
N opt
5
0.9
10
0.8
Figure 17. Optimum fin parameter, Nopt,
for a vertical rectangular fin with mois-
0.7
ture condensation. Adapted from Kilic and
25
30
35
40
Ta (C)
Onat (1981).
2.0
Dry Triangular
1.8
1.6
Dry Rectangular
1.4
N opt
Tfb = 0 C
1.2
Wet Triangular
10
1.0
0
Wet Rectangular
0.8
10
Figure 18. Comparison of Nopt for vertical
rectangular and vertical triangular fins un-
0.6
der dry and wet conditions. Adapted from
25
30
35
40
Toner et al. (1983).
Ta
Triangular fins
Toner et al. (1983) extended the analysis of the foregoing section to a vertical fin of
triangular profile (Fig. 16b). Figure 18 gives their final results showing how the optimum
value of N is affected by the variations of the ambient temperature Ta and fin base
temperature Tb. Also shown for comparison are the results for the optimum rectangular
fins. It can be seen that for a given Ta and Tb, the optimum value of N for a wet triangular
fin is lower than that of a dry triangular fin, and that Nopt decreases as Ta and Tb increase.
As noted earlier, the wet rectangular fin exhibits the same behavior. It is also interesting to
note that the values of Nopt for triangular fins (dry and wet) are higher than those of the
rectangular fins (dry and wet).
29
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