Abstract: A heat exchanger having a plurality of parallel pipes arranged in lines and strips of fin plates fixed to the pipes perpendicularly to the lengths thereof. Turbulence-forming structures are cut out of the fin plates and are bent up at 90.degree. with respect to the planes of the plates, such structures functioning as fin plate spacers and as baffles to direct a fluid medium of inferior heat transfer coefficient which flows in a direction parallel to the planes of the finned plates and perpendicularly to the pipes. The pipes are adapted to conduct a fluid medium of superior heat transfer coefficient. The turbulence-forming structures are disposed in lines on each side of the lines of pipes and in rows which are substantially tangential to the opposite sides of the pipes. The heat exchanger may have a plurality of lines of pipes spaced equally transversely from each other and transvetsely of the direction of flow of the fluid medium of inferior heat transfer coefficient.

Abstract: An internal fin tube heat exchanger comprises a cylindrical tube having on its inside a continuous heat exchange member with a plurality of legs branched from a central longitudinal extending member. The heat exchange member can be metal strip cut with a plurality of ribs disposed at an acute angle thereto, so that when the member is pulled into the tube, the ribs do not resist movement in one direction but do resist reverse movement in the opposite direction, which opposite direction is also the direction of flow of the fluid within the tube. Thus the fluid does not dislodge the heat exchange member. The ribs can be cut in various patterns and the strip is rotated when being drawn into the tube so as to impart a twist thereto, thereby to position the ribs all about the periphery of the tube. The ribs can have feet thereon that extend either peripherally of the tube or longitudinally of the tube.