| 摘要 |
PURPOSE:To reduce defrosting operation and improve comfortable property as well as energy efficiency by a method wherein a multitude of cut-out parts, whose positional pitches in the flow direction of air are reduced stepwisely from the inflow direction of air, is arranged on a fin located at an interval between heat transfer tubes in the direction of stage of the tubes. CONSTITUTION:In the inflow part of air for the fin 1, the positional pitch P1 of the cut-out part 4 is long from the leading edge of the fin, therefore, the thickness of temperature boundary layer is thick, the heat transfer coefficient at the side of local air is low and an absolute humidity difference of saturated wet air, corresponding to the temperature difference between ambient air and the heat exchanger which relates to the amount of frosting becomes small. Accordingly, the thickness of frost 3 in the inflow part of air for the fin 1 becomes thin. Since the positional pitches P24nP5 are reduced stepwisely with respect to the outflow direction of air and the thickness of temperature boundary layer becomes thin gradually, the cooled and dehumidified air effects heat exchange with the gradually cooled and dehumidified air and whereby the frost 3 is formed. According to this method,a space between fins will never be blocked, ventilating path may be secured widely, the deterioration of heat exchanging amount may be reduced and the number of times of defrosting operation may be reduced.
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