Abstract
This paper contains test data on continuous and non-continuous fins for liquids in the laminar-flow region. The data indicate that for longitudinal fin-tube “pipe-within-pipe” type heat exchangers, the transition range begins near Rh = 200. Correlation with earlier investigations on air with short longitudinal fins, for Rh > 600, indicates fair agreement with the authors’ results, when length of fin and inlet turbulence are taken into consideration. Noncontinuous fins promote turbulence in the laminar-flow region and increase fin-side heat-transfer coefficients up to 100 per cent, in the range of L = 10 ft. The theoretical aspects of fouling on fin tubes versus bare tubes are graphically illustrated, and actual semi-plant-scale fouling rates are plotted. These data show that fin tubes are affected less by fouling than bare tubes, because the effectiveness of the fin increases when fouling becomes greater.