| 摘要 |
PROBLEM TO BE SOLVED: To provide a fin tube in which even when a thermal conductivity of an inner tube member is small, heat exchange performance is enough improved. SOLUTION: A fin tube 1 includes an inner tube member 2 comprising low thermal conductivity stainless, and an outer tube member 2 comprising high thermal conductivity aluminum. A recessed portion 2a where a tube wall is recessed on the side of a center of the tube is formed in the inner tube member 2. The outer tube member 3 is fixed to or brought into close contact to or with an outer peripheral surface of the inner tube member 2 such that it fills the recessed portion 2a, and includes a fin section 3b formed therein. As a result, heat possessed by EGR gas flowing the neighbourhood of the central portion of a fluid passage 2b is discharged into air of an external fluid through aluminum filled in the recessed portion 2a and through the fin section 3b to effectively cool the EGR gas and hence satisfactorily improve heat exchange performance of the fin tube 1.
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