| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat exchanger having improved heat exchanging performance. SOLUTION: The heat exchanger comprises a sectionally flat tube 1 enlarged and mechanically joined to a plate fin 2. The tube 1 has circular portions 12 formed at both longitudinal ends in view form the flow direction of fluid in the tube, plane portions 13 opposed to each other for joining the both-side circular portions to each other, and columnar portions 14 extending to the flowing direction of the fluid in the tube for joining the plane portions 13 to each other. When the tube 1 is enlarged, the columnar portions 14 elongate greater with permanent stress being left, therefore preventing the spring back of the circular portions 12. Thus, a diameter D1 of the circular portion 12 and a size W1 between the opposed plane portions 13 are kept as long as enlarged even after an enlarging element is removed and adhesion is kept between the tube 1 and the plate fin 2, providing the improved heat exchanging performance. COPYRIGHT: (C)2005,JPO&NCIPI
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