To provide an inner-face-threaded tube whose weight (unit weight) per unit length is small, and which is easy of production by rolling roll, and besides is excellent in the evaporation property and condensation property of a refrigerant even in the low flow region of the refrigerant, and has high heat conduction performance.
This tube has inclination datum lines Pc at specified angles β(for example 5°) to the tube axis Ps of the inner face of a heat conductive tube 1, and discharge grooves 5 provided on the lines of the inclination datum lines Pc are put in face symmetry. This tube is equipped the first group 1a of fins being made at opening angles β1 (20°) from the inclination datum lines Pc in the first region, and the second group 2a of fins being made at opening angles β2 (20°) from the inclination datum line Pc in the second region. The fins 2 in the first fin group 1a and the fins 3 in the second fin group 2a arranged in face symmetry about the discharge group form many parallel grooves 4 in the shape of a truncated chevron (or a reverse truncated chevron) which are arranged with the inclination datum line Pc and the discharge groove 5 as the starting point of face symmetry.
KODAMA KENJI
TAKAYASU HIDEKI
