| 摘要 |
PURPOSE:To improve heat transfer rate by a method wherein both front and rear surfaces of a plate fin is provided with a multitude of louver type raised- slotted parts at an interval between heat transfer tubes and the sides thereof are slanted with respect to airflow. CONSTITUTION:Boundary layer leading edge effect, precluding the development of temperature boundary layer, is contrived by louver type raised-slotted parts 11a-11f. Further, the sides 11g'-11e' of the raised-slotted parts are formed so as to be slanted with respect to the inflow direction of the airflow B, therefore, the airflow B collides against said sides and generates eddies whereby the improvement of heat transfer performance due to the promotion of turbulent flow may be contrived. On the other hand, the airflow B flows along the raised- slotted parts and the sides thereof and flows into the back stream side of a heat transfer tube 13 whereby dead water areas 14a, 14b at the back stream side of the heat transfer tubes 13 are reduced remarkably and heat transfer performance may be improved. The boundary layer leading edge effect, the turbulent flow promoting effect and the dead water area reducing effect may be introduced and heat transfer rate may be improved markedly.
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