Abstract: A heat transfer device is provided which has an improved energy efficiency, utilizes significantly less space and costs less than conventional condensers in refrigeration units. The heat transfer device comprises a plurality of coil units disposed in a serpentine configuration and which are juxtapositioned to decrease space requirements and increase heat transfer. The coil units are constructed by fist attaching a lateral fin to a tube. The tube is then bent to form a continuous helical structure and this helical structure is then bent to form a plurality of parallel interconnected individual units disposed in a serpentine configuration. Multiple rows of interconnected parallel units are arranged to interfit so that the condenser occupies a minimum amount of space.

Abstract: A method and apparatus is provided for forming bends in a tube. A set of bend forming elements are mounted on each of a pair of parallel guideways. Each set of bend forming elements are interconnected by lazy tongs and a motor is provided to drive each set of bend forming elements along the guideways so that each set of bend forming elements may be moved together or separated while maintaining equal spacing between the elements. When a straight tube is placed between the sets of bend forming elements and the bend forming elements are driven together while the guideways simultaneously are driven apart, bends are formed in the tube to form the tube into a serpentine configuration. The bend forming elements have at least two different curvatures on their external surfaces so that the bends in the tube are formed in two stages with each of the different curvatures being sequentially operative to form the final bends in the tube.