GB800265A - Improvements in or relating to heat transfer element - Google Patents

Abstract

800,265. Making heat-exchange elements. DAVIES, G. April 17, 1956, No. 11721/56. Class 83 (2). [Also in Group XIII] A fin for a heat-transfer element is made by making a series of cuts 2a extending inwardly front both longitudinal edges 3, 4 of a metal strip, to form a series of aligned pairs of ribs 5 extending from a sping 6, and bending the ribs out of the plane of the strip, and inwardly of the spine to position the free ends 9 of each pair in abutting relationship over the spine and spaced therefrom. The ribs may be curved throughout their length or they may only be curved near their outer ends, Fig. 9 (not shown). The strip is preferably of copper or aluminium and may have a thick centre part 11 forming the spine 6, Fig. 5, and tapered edge portions 12 forming the ribs. One side 13 of the strip may be flat or both sides may taper, Fig. 6 (not shown). After cutting and bending of the ribs the fin 10 is curved into a helix, Fig. 4. The cutting, bending and longitudinal curving of the fin may be performed by a single set of guillotine blades. To form a heat-transfer element, the fin is wound under tension on a tube 19, Fig. 7, preferably as it leaves the guillotine, the tube being rotated intermittently to facilitate winding. To aid heat transfer the tube may be coated with powdered aluminium, copper or other metal. Flanges 20 soldered to the tube have fingers 21 engaging the adjacent ribs to hold the fin in position. Alternatively the fin may be brazed or soldered to the tube, e.g. by dipping in a solder bath which also solders together the abutting ends of the ribs 5.