HEAT EXCHANGER

PROBLEM TO BE SOLVED: To provide a heat exchanger having a small-sized and inexpensive leak detecting structure while ensuring a high heat exchange efficiency. SOLUTION: The heat exchanger 1X comprises a triple tube 1, and the triple tube 1 includes a middle tube 3 substantially concentric with an inner tube 2 and containing the inner tube 2, and an outer tube substantially concentric with the middle tube 3 and containing the inner tube 3. In the triple tube 1, only the middle tube 3 is formed of a dissimilar tube having continuous irregularities 5 and projections 6 on both inner and outer walls of a circular tube. According to this, since a plurality of small grooves 7 and a plurality of passages 8 which form the leak detecting structure can be formed in the middle tube 3 by forming the small grooves 7 with the inner tube 2 by the continuous irregularities 5 partially closely fitted to the inner tube 2, and the plurality of passages 8 with the outer tube 4 by the projections 6 closely fitted to the outer tube 4, the number of dissimilar tubes with high unit cost, which are needed to form the small grooves 7 and the passages 8, can be reduced to one while ensuring a sufficient heat transfer area between fluids to obtain a high heat exchange efficiency. Consequently, a heat exchanger having a small-sized and inexpensive leak detecting structure while ensuring a high heat exchange efficiency can be obtained. COPYRIGHT: (C)2006,JPO&NCIPI