Abstract: A progressive die for forming a turbulator having multiple rows of axial corrugations. The corrugations are slit and offset such that artificial turbulence is generated as it passes through the corrugations. The device includes a plurality of dies disposed along an axial material direction. A flat strip of material enters the dies and is folded about its longitudinal axis in a relatively wide V-fold. As the strip of material moves forward, it is intermittently stamped in the series of dies. The initial dies create a central V-shaped fold that gradually narrows into a U-shaped channel with straight walls. Once the first corrugation is formed, a series of progressive dies form the remaining corrugations in alternating fashion. Next, the material moves through a slitting station that provides apertures and an axial offset such that adjacent sections of the corrugation are slit and offset in the axial direction.

Abstract: A serpentine louvered heat exchange element comprising a folded metallic strip having a length and width wherein the length is over ten times the width prior to being folded. The strip has back and forth folds with legs having substantially equal lengths defined therebetween. A plurality of the legs are provided with louvres having openings which allow the passage of fluid. Each of the folds have a fold apex with an observable preformed fold arc.