Tube for heat transfer
A tube for heat transfer in which the inner surface of the tube is grooved into a pattern. The pattern includes a first fin ( 10 ) and a second fin ( 20 ) which have different shapes, wherein the first fin comprises a shaft and a head integrally formed, the shaft extending from the inner surface in a direction away from the inner surface, the head extending from the shaft in a direction away from the inner surface. In a transverse cross section of the tube, the circumferential width of the head is larger than that of the shaft.
1. A tube for heat transfer, an inner surface of the tube being grooved into a pattern, the pattern including a first fin and a second fin which have different shapes, wherein the first fin comprises a shaft and a head integrally formed, the shaft extending from the inner surface in a direction away from the inner surface, the head extending from the shaft in the direction away from the inner surface, characterized in that in a transverse cross section in respect of a longitudinal axis of the tube, a circumferential width of the head is larger than that of the shaft, wherein a number of the first fin in a circumference of the tube is an integer multiple of a number of the second fin in the circumference of the tube, wherein the integer multiple is greater than or equal to two, and the second fin is spaced by the first fin.
2. The tube according to claim 1 , wherein in the transverse cross section of the tube, a fin height in a radial direction of the first fin is higher than that of the second fin.
3. The tube according to claim 2 , wherein the height of the second fin is ⅓ to ½ of the height of the first fin.
4. The tube according to claim 1 , wherein the number of the first fin in the circumference of the tube is the same as the number of the second fin in the circumference of the tube, and the first fin and the second fin are alternately arranged.
5. The tube according to claim 1 , wherein in the transverse cross section of the tube, a height in a radial direction of the head is less than or equal to that of the shaft.
6. The tube according to claim 1 , wherein in the transverse cross section of the tube, a width in a circumferential direction of the head either increases with the head extending away from the inner surface, or first increases with the head extending away from the inner surface and then decreases toward the tip of the head.
7. The tube according to claim 6 , wherein in the transverse cross section of the tube, a width in a circumferential direction of the shaft is constant with the shaft extending away from the inner surface.
8. The tube according to claim 1 , wherein in the transverse cross section of the tube, a width in a circumferential direction of the second fin decreases with the second fin extending away from the inner surface.
9. The tube according to claim 8 , wherein an addendum angle of the second fin is 5° to 60°.
10. The tube according to claim 1 , wherein a dedendum of the first fin and that of the second fin are smoothly connected, at a first corner and a second corner respectively, to the inner surface of the tube with a curve transition.
11. The tube according to claim 1 , wherein the first fin and the second fin each extends at an angle with respect to the longitudinal axis of the tube so as to form inner threads on the inner surface of the tube.
12. The tube according to claim 11 , wherein the first fin and the second fin each has constant transversal cross section along the longitudinal direction of the tube.
13. The tube according to claim 11 , wherein an angle between the internal threads and the longitudinal axis of the tube is 0° to 60°.
14. The tube according to claim 13 , wherein the angle between the internal threads and the longitudinal axis of the tube is 2° to 45°.
15. The tube according to claim 1 , wherein the tube is seamless.