| 摘要 |
This document describes a bi-thermal heat exchanger, of the condensing type, comprising tubular components (1) formed by at least a first pipe (2), wherein a first fluid can flow, and by a second pipe (3), wherein a second fluid can flow, in which the two pipes (2, 3) are positioned one inside the other; the external surface of the first pipe (2) can be heated by means of the flues produced by a burner, so that the first pipe (2) yields heat to the first fluid, the first fluid yields heat to the second pipe (3) and the latter finally yields heat to the second fluid. According to the invention, - at least one pipe (2) is composed of two parts (2A, 2B), each made of different materials; -at least the surfaces of said pipes (2, 3) that are in contact with said first fluid are made of the same material; -at least the external surface of said first pipe (2) is made of a material having characteristics of high thermal conductivity and and high resistance to corrosion on the part of the acid condensates of said flues; -at least the internal surface of said second pipe (3) is made of a material compatible from an alimentary point of view with said second fluid.
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