| 摘要 |
PURPOSE:To decrease draft resistance in curved parts, to utilize the heating surface of curved parts effectively, and to increase heat transfer coefficient, by determining the fin pitches of the inside rows of curved parts larger than those of the outside rows of curved parts. CONSTITUTION:In a heat exchanger 17 before curved parts are formed in a heat exchanger 11, the fin pitches fP11 of curved parts A of a group of fins being inserted into a group of heat exchanger tubes 13 which are to be the inside rows of curved parts are determined larger than the fin pitches fP12 of the other parts. Accordingly the fin pitches fP13 of the inside rows of curved parts A are larger than the fin pitches fP14 of the outside rows of curved parts A in the heat exchanger 11, and draft resistance at the time when air passes through the curved parts A is decreased. Therefore the air rate passing through the curved parts A increases, the curved parts A can be utilized effectively as heating surfaces; as a result, the heat transfer coefficient to a heat exchanger can be increased.
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