| 摘要 |
<p>A flattened heat-transfer tube (3) is formed by superimposing on each other a pair of plane portions (7) provided at both ends of a plate of aluminum alloy are superimposed on each other to thereby form a joint (8). The joints (8) are positioned on the downwind side, and folded portions (6) having a U-shaped cross section are positioned on the windward side. Accordingly, there is a tendency to spread kinetic energy of foreign substances resulting from collision with the folded portions over their entirety, thereby preventing the application of high degree of stress to part of the flattened heat-transfer tubes, as well as contributing to improvements in the durability of the flattened heat-transfer tubes.</p> |
