complex d alettatura and tube for heat exchanger with alettatura shrouded propeller

摘要

1382783 Finned heat exchange tubes WESTINGHOUSE ELECTRIC CORP 30 July 1973 [2 Aug 1972] 36247/73 Heading F4S A fin strip provided with two series of transversely extending slits 16 and 18 and folded longitudinally so as to have a U-shaped crosssection is wound helically on a tube 28 so that the base portion 10 is in contact with the tube and the leg portions 12 and 14 project outwardly therefrom. Each of the slits 16 extends from a point 20 adjacent the base portion 10 to a point 22 just short of the outer longitudinal edge 24 of the leg portion 12 or 14, whereas each slit 18 extends from the outer edge 24 inwardly to a point 26 well short of the base portion. The distance between the point 22 and the edge 24 is less than the distance between any two successive slits. During the winding operation the slits 16 and 18 open up to form the expanded radial fin pattern shown in Fig. 3. The slits in one leg portion may be offset from those in the other leg portion. In an alternative embodiment (not shown), the fin strip has only one leg portion extending from the base portion 10 to define an L-shaped cross-section.