To provide the heat transfer tube having an inner face groove capable of promoting boiling of a nonazeotope coolant by turbulent flow and further improving a heat transfer coefficient in evaporation or condensation.
The heat transfer tube is constructed so that discontinuous in the tube axial direction, prescribed length, small, many first kind grooves 10 and second kind grooves 11 are helically for the axial direction and alternately formed on a metal tube 1 inner face. While drawing the metal tube 1 in a fixed direction, by a first grooved plug 30 and an appropriate number of first stage working balls 50, further remaining a helical flat smooth part 12, the discontinuous in the tube axial direction, prescribed length, small many first kind grooves 10 are helically formed on a tube inner face, successively, by a second grooved plug 31 and an appropriate number of first stage working balls 51, the discontinuous in the tube axial direction, prescribed length, small, many second kind grooves 11 are helically formed to the helical flast smooth part 12 of a metal tube 1 inner face.
YAMAMOTO KOJI
HASHIZUME TOSHIAKI
