EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER FROM TRANSVERSE FINNED TUBES WITH LONGITUDINAL FLOW
Results of pressure drop and heat transfer measurements for longitudinal flow along tubes with transverse fins were obtained for Reynolds-numbers between 1000 and 150 000. The finned tubes investigated were the inner tubes of an annulus. The height of the fins was 1 mm, the pitches ranging from 1.5 mm to 24 mm. The outer diameter of the fins was 18.5 mm and the inner diameter of the annulus 38 mm. It is shown, that heat transfer performance of finned tubes with this geometry reaches its optimum when the ratio of fin pitch to fin height lies between 1 and 3. In this range also the pressure drop is considerably smaller than in cases where less fins with larger spacing are adopted for turbulence promotion. Therefore, finned tubes with these geometries appear to be advantageous for application in heat exchangers.