| 摘要 |
PURPOSE:To contrive the cost down and the improvement of heat transfer performance of the heat exchanger by a method wherein belt-type protuberances, formed continuously on the front and rear surfaces of a fin so as to be opposed to the airflow in the heat exchanger, are provided on the flat fin between heat transfer tubes. CONSTITUTION:The finned heat exchanger is formed by a method wherein the heat transfer tubes 8 are inserted vertically into the fin collars 7 of the flat plate fin 6 and the fin collars 7 and the heat transfer tubes 8 are integrated by expanding the heat transfer tubes 8 from the inside thereof. Upon expanding the tubes, the belt-type protuberances 10 are formed continuously on the front and rear surfaces of the flat plate fin 6 between the heat transfer tubes in parallel to the longitudinal direction of the fin 6 where by the flat plate fin 6, weakened in the strength thereof by providing slit type cut-ups 11, can be reinforced sufficiently and smooth expanding work of the tube may be effected. The airflow, passing between the slit type cut-ups 11 provided on the front and rear surfaces of the flat plate fin 6, collides against the belt type protuberances 10 and the flow thereof is disturbed, whereby the formation of temperature boundary layer is interferred. Accordingly, a temperature gradient on the surface of the fin is increased and heat exchange between the fins and the airflow is promoted, whereby the heat transfer coefficient may be improved.
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