Heat transfer tubes and method for manufacturing
AssigneeMitsubishi Shindoh Co., Ltd.
InventorsSeizo Masukawa, Shunroku Sukumoda
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Abstract
The heat transfer tube of the present invention is provided in an inner surface thereof with a plurality of main grooves and a plurality of narrow grooves. The main grooves have rectangular shaped cross sections, parallel to one another, and extend at an angle to the longitudinal direction of the heat transfer tube. The narrow grooves are formed parallel to one another, extend independently of the main grooves. Each of the narrow grooves has a bottom face and a pair of side faces, the side faces are inclined closely toward the bottom face, and each of the side faces and a part of the bottom face form sharp cuts.
Claims11
A heat transfer tube having an inner surface in which are formed:
- (a) a plurality of main grooves, having a rectangular shaped cross section and parallel to one another, extending at an angle to a longitudinal direction of the heat transfer tube,
- (b) a plurality of narrow grooves, being parallel to one another, extending at an angle to the longitudinal direction of the heat transfer tube, each of the narrow grooves having a bottom face and a pair of side faces, the side faces being inclined closely toward the bottom face, thereby each of the side faces and the bottom face forming a sharp cut respectively, wherein an angle between the inner surface of the heat transfer tube and a depth direction of each of the cuts is less than 20.degree..
Dependencies are inferred from the claim text.