| 摘要 |
PURPOSE:To secure heat exchanging capacity and lengthen a permissible time to continue the operation of the heat exchanger even when frosting is caused by a method wherein a plurality of cut-up pieces are arranged on a flat sheet fin between heat transfer tubes and at the upstream side of the heat transfer tubes. CONSTITUTION:The cut-up pieces 9a, 9b, 9c are provided on the flat sheet fin 5 in the area of upstream side of airflow 8 with respect to the heat transfer tubes 7 so as to be slanted with respect to the flow direction of the airflow while the cut-up pieces 10a, 10b are provided at the down-stream side area of the cut-up pieces 10a, 10b are provided at the down-stream side area of the same so as to be slanted to a direction reverse to the inclinations of the cut-up pieces 9a, 9b, 9c. On the other hand, slit type or louver type cut-ups 11a, 11b, in which two sides, opposing to the airflow, are cut up and opened, are provided on the flat sheet fin 5 at the leading edge thereof. The flow of heat from the upstream side leading edge of the flat sheet fin 5 to the heat transfer tube 7 is limited, therefore, temperature at the leading edge part in the upstream side of the heat transfer tube is comparatively high and the amount of frosting in this area may be reduced. When the airflow collides against the cut-up pieces, another airflow having whirling component is generated, therefore, the heat transfer coefficient at the airflow side of the flat sheet fin 5 may be increased by the turbulent flow promoting effect of the whirling airflow.
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