| 摘要 |
When forming fins and heat transfer tubes by aluminum material, a pressure loss in the tube does not increase and a heat exchanger can be provided having heat transfer performance equal to or higher than a copper tube. The heat exchanger includes fins made of an aluminum material having a low deformation resistance and heat transfer tubes made of an aluminum material having a higher deformation resistance than the aluminum material forming the fins, and on whose internal surface the groove is provided to penetrate the fin to be fixed. It is also arranged that the tube axial direction (a) of the inner surface of the heat transfer tube and the direction (b) of the groove provided on the internal surface of the heat transfer tube are substantially parallel. In this case, the groove direction (b) forms an angle of 0 degrees to 2 degrees with respect to the tube axial direction (a) of the inner surface of the heat transfer tube. The depth of the groove of the heat transfer tube after tube expansion is 0.2 mm to 0.3 mm, and the top width of the ridge top portion is 0.08 mm to 0.18 mm. Further, the number of grooves of the heat transfer tube 20 is 40 to 60, and an apex angleαis 5 degrees to 20 degrees.
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