DOUBLE-TUBE HEAT EXCHANGER AND REFRIGERATING CYCLE DEVICE

摘要

This double-tube heat exchanger is equipped with: an inner tube (2) through which a first fluid passes; an outer tube (1) having a larger diameter than the inner tube (2) and which covers the inner tube (2), a second fluid flowing in between the inner tube (2) and the outer tube; and a heat transfer area expanding tube (3) which is provided to the space between the inner tube (2) and the outer tube (1), and which has a shape of protrusions and recesses and is configured in such a manner that the length in the tube circumferential direction of the inside contact part (6) that comes into contact with the outer wall of the inner tube (2) is longer than the outside contact part (7) which is the length in the tube circumferential direction of the part that comes into contact with the inner wall of the outer tube (1), and that the fin parts between the outside contact part (7) and the inside contact part (6), traversing the space in the tube cross section, come into contact with the outer wall of the inner tube (2) and the inner wall of the outer tube (1) in a diagonal direction.