DUPLEX TUBE HEAT EXCHANGER, ITS MANUFACTURING METHOD AND SECONDARY REFRIGERANT TYPE AIR CONDITIONER USING DUPLEX TUBE HEAT EXCHANGER

摘要

PROBLEM TO BE SOLVED: To improve performance of a duplex tube heat exchanger. SOLUTION: A secondary refrigerant passage 4 in a clearance between positions of inner pipes 3A-3D and an outer pipe 1 is maintained constant by spacers 7 mounted with specified intervals by arranging a plurality of inner pipes 3A-3D twisted in a spiral shape respectively around an shaft center of the outer pipe 1 inside the outer pipe 1. A heat exchanging area is increased by making the inner pipes in a spiral shape of a plurality of numbers, and the heat transfer performance is increased by promoting turbulence of water flowing in the secondary refrigerant passage of the outer pipe and the inner pipes.