| 摘要 |
PURPOSE:To shorten the distance of approach run of fluid, lengthen turbulent flow area in the tube and display prominent performance of heat transfer tube by a method wherein the pitch of a spiral groove provided on the inner surface of the tube is increased gradually from the inlet port side of the tube toward the outlet port side thereof. CONSTITUTION:A distance from the inlet part of the heat transfer tube 1 to the turbulent flow area is shorter than before and the pitches of the grooves 2, 2 in a transit area, in which the fluid arrives at a perfect turbulent flow area, is shorter than before. The pitches P of the grooves 2, 2 in the boundary part between the transit area and the turbulent flow area are substantially equal to the same of conventional tube. Since the tube is formed so that the pitches P of the grooves 2, 2 are increased gradually toward the outlet port side of the tube and the friction coefficient lambdag of the flow of liquid is reduced, therefore, increase of pressure loss of the liquid is reduced and the energy of flow of liquid is not deteriorated so much. Accordingly, good turbulent flow is generated along the whole length of the heat transfer tube 1 substantially and the heat transfer performance, more excellent than before, may be displayed. |
