| 摘要 |
PROBLEM TO BE SOLVED: To provide a double pipe for a heat exchanger, having a structure capable of being used without generating noise in operation, and providing high heat exchanging performance.SOLUTION: A double pipe 1 for a heat exchanger has a double pipe structure configured by disposing an inner pipe 2 inside of an outer pipe 10, and exchanging heat between a fluid flowing inside of the inner pipe 2 and a fluid flowing between the inner pipe 2 and the outer pipe 10. The inner pipe 2 has the shape having two projecting sections 21, and positions of the projecting sections 21 are spirally displaced in the longitudinal direction. The outer pipe 10 has the shape of a circular smooth pipe at least at a cross-section of an inner peripheral face. The inner peripheral face of the outer pipe 10 and apex parts 210 of the projecting sections 21 of the inner pipe 2 are kept into contact with each other, and an outer flow path 31 defined in the circumferential direction, is formed between the outer pipe 10 and the inner pipe 2. A diameter d1 of an inscribed circle of the inner pipe 2 and a diameter d2 of an inscribed circle of the outer pipe 10 have the relationship of 0.6<d1/d2. |
