Method for providing improved nucleate boiling surfaces

摘要

An improved nucleate boiling surface can be obtained on a metal heat transfer tube or other form of heat transfer member by knurling or otherwise deforming a smooth surfaced member to notch and partially work harden its surface and then subjecting the knurled portion to a finning operation. The method results in small splits or ruptures of a controlled geometry and depth being produced in the tip area of the fins which become nucleation sites for boiling enhancement. Preferably, the knurling rolls are mounted on the same arbors as the finning disks so that a tube is progressively knurled and then finned in a single pass through the apparatus. If desired, the tube can also be internally ridged as it is being externally finned.