Longitudinally-finned cross-flow tube banks and their heat transfer and pressure drop characteristics

Heat transfer and pressure drop experiments were performed for cross-flow tube banks in which the individual tubes were equipped with longitudinal fins. The investigated geometrical parameters included the placement of the fins (at the front of the tube, at the rear, and at the front and rear), the fin tip shape (blunt or contoured), and the fin thickness. For each tube bank geometry, the Reynolds number was varied by nearly an order of magnitude. The results showed that a high degree of heat transfer enhancement can be obtained by finning, and the enhancements for the various tube bank geometries were compared at fixed pumping power, fixed pressure drop, and fixed mass flow. The finning-related enhancements were also compared with those attainable by the use of increased diameter unfinned tubes. Finning was found to be especially advantageous when the comparison is made at fixed pressure drop. For an array with fixed tube centers, finning permits greater additions of surface area than are possible by increases in the tube diameter.