| 摘要 |
PURPOSE:To improve a heat transfer rate between air and the front surface of a fin by disposing cut and raised portion groups on the front and rear sides symmetrically with respect to a vertical bisector of a line connecting the centers of heat transfer pipes. CONSTITUTION:A finn 9 is provided at its front side 9a with cut and raised portions formed by cutting and raising to open two-side parts 13a, 13b-17a, 17b. Lines connecting side ends 13c-15c and 15c-17c and 13d-15d which are connected to respective cut and raised portions form a cut and raised portion group 18 having angles of inclination horizontally symmetric on the border of line G-G rpresentative of centers in the step direction of heat transfer pipes 11. On the rear side 9b a cut and raised portion group 23 is similarly formed. These cut and raised portion groups 18 and 23 on the front and rear side of the fin are disposed and formed symmetrically with respect to the vertical bisector F-F of the line G-G. As a result, a flow and a turbulence having turning components are induced in air flowing between fins thereby to greatly improve the heat transfer function.
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