FIN-AND-TUBE TYPE HEAT EXCHANGER, AND ITS RETURN BEND PIPE

摘要

The invention provides a fin-and-tube heat exchanger using a return bend tube that allows further enhancement of the evaporative performance of the heat exchanger. The fin-and-tube heat exchanger, where a refrigerant is supplied inside tubing, has a hairpin tube portion where a plurality of hairpin tubes are arranged, a return bend tube portion where there are arranged a plurality of return bend tubes joined to respective hairpin tube ends of the hairpin tube portion, and a fin portion comprising a plurality of fins arranged at a predetermined spacing on the outer surface of the hairpin tubes. The heat exchanger comprises first grooves formed on the tube inner surface of the return bend tube. A first groove pitch (P1) of the first grooves in a cross section perpendicular to a tube axis, and a second groove pitch (P2) of spiral-shaped second grooves formed on the inner surface of the hairpin tube in a cross section perpendicular to a tube axis, satisfy a groove pitch ratio (P1/P2) of 0.65 to 2.2, while a first groove cross-sectional area (S1) per groove of the first grooves in a cross section perpendicular to the tube axis, and a second groove cross-sectional area (S2) per groove of the second grooves in a cross section perpendicular to the tube axis satisfy a groove cross-sectional area ratio (S1/S2) of 0.3 to 3.6.