Shell and tube heat exchanger, finned tubes for such heat exchanger and corresponding method

Abstract

A shell and tube longitudinal flow heat exchanger comprising a containment casing within which a first fluid can flow substantially parallel to the longitudinal axis of said casing, said containment casing accommodating in its interior a bundle of tubes substantially parallel to one another and parallel to the longitudinal axis of said casing and a plurality of grid-shaped baffles substantially transverse to the longitudinal axis of said casing supporting said tubes, a second fluid flowing in said bundle of tubes. Said tubes are provided on at least a part of their outside surface with a plurality of low fins, which are helically arranged on the outer surface of said tubes with a first angle of advancement a and having a profile interrupted by helical grooves having a second angle of advancement β, with α≠β.

What is claimed is: 
     
         1 . A method for manufacturing a finned tube using a machine comprising a working assembly and at least one support assembly, said first working assembly comprising a first rotating finning tool and a second rotating finning tool mounted in sequence on a same driving axis, said first rotating finning tool being provided with a first helical working profile having a first angle of advancement α 1  and said second rotating finning tool being provided with a second helical working profile having a second angle of advancement α 2 , with α 2  # α 1 , the method comprising advancing said tube on a plane defined by said support assembly, forming a first fin on said tube by said first rotating finning tool, forming a second fin on said tube by said second rotating finning tool, the formation of said second fin being immediately subsequent to the formation of said first fin, and a height h of said first fin being lower than a height H of said second fin. 
     
     
         2 . The method for manufacturing a finned tube according to  claim 1 , characterized in that the relative angle between said first angle of advancement α 1  and said second angle of advancement α 2  is between 30° and 60°, and in that the height h of said first fin is ≤0.5 mm, and the height H of said second fin is ≤2 mm.