HEAT TRANSFER TUBE WITH GROOVED INNER SURFACE

PROBLEM TO BE SOLVED: To provide a heat transfer tube with a grooved inner surface which can reduce the risk of compressor failure by exhibiting excellent evaporation performance and improving oil return.SOLUTION: The heat transfer tube with the grooved inner surface, includes a main tube 21 which, on an inner peripheral surface thereof, has: a plurality of helical grooves 22 with a helix angle which are arranged parallel; and a plurality of fins 23 arranged between the plurality of grooves 22, respectively. The inner diameter of the heat transfer tube is more than or equal to 2.5 mm and less than or equal to 6.5 mm with reference to the bottom of the groove 22 of the main tube 21, and the height of each of the fins 23 is more than or equal to 0.1 mm and less than or equal to 0.25 mm. Further, 0.04≤W/ID≤0.1 is satisfied when the bottom width of the each groove 22 is denoted by W.