PURPOSE: To improve the condensation efficiency and evaporation efficiency by forming fins in spiral while keeping the formation rate of (sectional height of fin/pitch of fin) ≥1/2, and cutting out the fins and providing a number of fine convexes and concaves on the inner surface of the pipe.
CONSTITUTION: The fins are provided spirally on the inner surface of the heat conductor pipe 1. In this instance, (sectional height of fin/pitch of fin) ≥1/2 is maintained. In order to obtain a high speed flowdown of a condensate, a plurality of imaginary spiral lines which run in parallel to the pipe axis or in the reverse direction at an angle less than 10° are crossed, so that the resultant intersecting point forms a cutout 4. In addition, for improving the evaporation efficiency, the inner surface of the pipe 1 is provided with a fine convex-concavo pattern.
SANADA KAZUSUKE
MATSUSHITA TOMIHARU
YAMAZAKI TATSUO
ISOZAKI AKIO
