| 摘要 |
PROBLEM TO BE SOLVED: To provide a double-pipe heat exchanger capable of advantageously exhibiting heat transmission promotion effects even when fluid made to flow to a gap between an inner pipe and an outer pipe has a low flow rate. SOLUTION: On a pipe outer peripheral face of the outer pipe 14, a recessed part 16 spirally and continuously extended to the pipe axial direction is formed, and a plurality of recesses 18 are formed in the bottom part of the recessed part 16 and arranged in the extending direction of the recessed part 16 at fixed intervals. On a pipe inner peripheral face of the outer pipe 14, a projecting part 20 corresponding to the recessed part 16 is spirally formed, and a plurality of projections 22 corresponding to the recesses 18 are formed independently so as to project to the pipe inner side at to part of the projection part 20. The inner pipe 12 is inserted to inside of the outer pipe 14 and arranged, so as to constitute the double-pipe heat exchanger 10. COPYRIGHT: (C)2009,JPO&INPIT
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