| 摘要 |
<p>The tube (1) has central channels (3, 4), and a metallic sheet comprising ends independently fixed on one of large sides of the tube. An anti-corrosion layer and a brazing layer are placed on internal and external surfaces of the sheet, respectively. The channel (3) has a lower side (12) and a side (13) close to the channel (4), where the sides have double wall thickness. The sheet is folded at folding lines (6-10, 6'-10').</p> |
