Abstract: A heat-exchange apparatus comprising a plurality of tubes bundled together, each having segmented twisted segments is disclosed. Each of the plurality of tubes provides a tube body defining an interior passageway for carrying a first fluid and a plurality of segments along its length comprising a straight section and a twisted section that are in fluid communication with each other. Each of the plurality of tubes provides a central longitudinal axis along its length. The tube body along the twisted section exhibits rotation about the central longitudinal axis and the tube body along the straight section exhibits no rotation. An exterior surface of the tube body of a tube can come into contact with an exterior surface of the tube body of another tube along the twisted section, whereas the exterior surfaces of such tubes avoid contact along the straight section.