| 摘要 |
A double pipe heat exchanger includes an inner pipe 2 inside which a first fluid passes, an outer pipe 1 that has a diameter larger than the diameter of the inner pipe 2 and that covers the inner pipe 2, and second fluid passes through a space between the outer pipe 1 and the inner pipe 2, and a heat transfer area enlargement pipe 3 that is provided in the space and that has a projection-depression shape in which a length in the pipe-circumferential direction of inner contact portions 6 to be contact areas with the outer wall of the inner pipe 2 is made to be larger than a length in the pipe-circumferential direction of outer contact portions 7 to be contact areas with the inner wall of the outer pipe 1, and in addition, fin portions between the outer contact portion 7 and the inner contact portion 6 that traverse the space in a pipe cross section come into contact with the outer wall of the inner pipe 2 and the inner wall of the outer pipe 1 in oblique directions. |
