| 摘要 |
PURPOSE:To enable the increase in performance and miniaturization of a tube and provide a heat transfer tube excellent in heat transfer efficiency and flexibility by a method wherein a plurality of spiral grooves are formed in the inner surface and the upper parts on the crest parts of the grooves are formed into nearly smooth plane and the circumferential width in the pocket part of the groove is made larger than that at the inlet and a wall part is formed into spiral wave shape. CONSTITUTION:A plurality of spiral grooves 5 are placed in the inner surface of a heat transfer tube and the upper surface 12 of the crest parts 11 located across the grooves 5 is formed into nearly smooth plane and the circumferential width W2 in the pocket part 8 of said groove 5 is formed larger than the circumferential width W1 in the inlet of said groove 5. Consequently, the liquid in the groove 5 receiving heat from outside the tube generates a number of boiling cores in preference to the upper part 12 of the crest part 11 and these minute boiling cores pass through the inlet 7 in growing up and make heat transfer accompanied by agitation to the fluid in the tube. Further, as on a tube wall 9 spiral undulation is processed with a period of pitch alpha, the fluid part of the tube inside surface and heat transfer between the tube inside and outside can be efficiently achieved. |
