| 摘要 |
PROBLEM TO BE SOLVED: To eliminate coats due to liquid from the surface of a gas capturing part and a nuclear boiling zone to improve the efficiency of heat exchange, by providing the outer surface of a heat transfer tube with fin convolutions and notches at prescribed intervals and at a prescribed tilt angle. SOLUTION: A heat transfer tube 10 has an external fin convolution 20, which is provided helically about the circumference of the tube, and notches 30 are provided on the circumferential surface of the tube across the fin convolution at prescribed intervals at a tilt angleαwith respect to a longitudinal axis AT of the tube. The notches 30 separate the fin convolution into a base portion and a spike part having a single flattened tip portion 23. Moreover, the spike part is located between a pair of adjacent notches, and an axisβof the tip portion is tilted with respect to the base axis of the notch 30. The maximum width of the spike part is greater than the maximum width of the base portion, and it is formed sufficient wide to allow both of the spikes of the adjacent fin convolutions to overlap each other. |
