RETURN BEND TUBE, AND FIN AND TUBE TYPE HEAT EXCHANGER

摘要

PROBLEM TO BE SOLVED: To improve evaporation performance of a heat exchanger.

SOLUTION: The return bend tube 1 is joined to a tube end of a hairpin tube provided with multiple fins arranged in parallel with each other at certain intervals on an outer surface, and it is used in the fin and tube type heat exchanger with a coolant supplied into a tube interior. It is provided with a first groove 2 formed on a tube inner face of the return bend tube 1. When a first groove pitch in a tube axis orthogonal cross section of the first groove 2 is P1 and a second groove pitch in a tube axis orthogonal cross section of a spiral second groove formed on an tube inner face of the hairpin tube is P2, a groove pitch ratio P1/P2 satisfies 0.65-2.2. When a first groove cross-sectional area per one groove in the tube axis orthogonal cross section of the first groove 2 is S1, and a second groove cross-section area per one groove in the tube axis orthogonal cross section of the second groove is S2, a groove cross-sectional area ratio S1/S2 satisfies 0.3-3.6.

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