Abstract: A method of bending a tube arrangement including an inner tube disposed within an outer tube is performed using a bending die having a concave groove including a curved portion extending around a peripheral surface of the bending die, the curved portion of the concave groove having at least one ridge projecting therefrom. The tube arrangement is located within the concave groove and a force is applied to the tube arrangement in a direction toward the curved portion of the bending die to cause the tube arrangement to conform to the shape of the concave groove. The at least one ridge projecting from the concave groove causes the outer tube to deform such that an interior surface of the outer tube contacts an exterior surface of the inner tube, securing a position of the inner tube within the outer tube.

Abstract: A heat exchanger includes an outer tube and an inner tube coaxially arranged within the outer tube. Both of the outer tube and the inner tube include a fluid channel formed therein. A first fluid flows through the fluid channel of the outer tube, and a second fluid, in heat exchange relationship with the first fluid, flows through the fluid channel of the inner tube. At least one heat conductive feature is formed between the outer tube and the inner tube, and on an inner surface of the inner tube to maximize a heat exchange between the fluids.