HEAT TRANSFER PIPE FOR OVERCOOLING DOUBLE-PIPE HEAT EXCHANGER

摘要

PROBLEM TO BE SOLVED: To provide a heat transfer pipe for an overcooling double-pipe heat exchanger capable of reducing the head loss of annulus fluid while improving the coefficient of heat transfer when running low viscous fluid through an annular part of a double-pipe heat exchanger at a high flow rate.SOLUTION: A heat transfer pipe for an overcooling double-pipe heat exchanger comprises: a plurality of trapezoidal projections formed on a pipe external surface to a rectangular shape in plan view so as to align in a pipe axial direction and a tube circumferential direction; and one or a plurality of ribs spirally formed on a pipe inner surface. In the projections, the width of a first groove between projections adjacent to each other in the pipe axial direction ranges from 0.3 mm to 0.80 mm; and the width of a second groove between projections adjacent to each other in the tube circumferential direction ranges from 0.10 mm to 0.30 mm. In the ribs, the width of a groove between ribs adjacent to each other in the pipe axial direction ranges from 0.15 mm to 1.10 mm; and a lead angle, which is an angle of the rib to the pipe axial direction, ranges from 40° to 65°.