Tube for heat exchange

Abstract

The present invention relates to a device for heat exchange between a hot gas and a liquid coolant. The tube has a flat configuration, with intermediate channels formed by a set of fins and two lateral channels with a larger hydraulic diameter. The invention is characterized by a specific way of reducing the passage section in order to prevent a by-pass effect in the tube so that gas flow is directed mainly through the set of fins.

1 . Tube ( 1 ) adapted for heat exchange between a hot gas and a liquid coolant wherein:
 the tube ( 1 ) has a flat configuration, configured by means of two essentially parallel flat walls ( 1 . 1 ) extending along a longitudinal direction (X-X′) and joined on both sides by means of a curved wall segment ( 1 . 2 );   the tube ( 1 ) comprises a set of fins ( 1 . 3 ) housed inside the tube ( 1 ) extending from the inner surface of one flat wall ( 1 . 1 ) to the inner surface of the other flat wall ( 1 . 1 );   the set of fins ( 1 . 3 ) comprises a plurality of internal channels (C) and a lateral channel (C l ) on each side, the lateral channel (C l ) being the one formed between the group of fins ( 1 . 3 ) and the curved wall segment ( 1 . 2 );   the hydraulic diameter (D h ) of the lateral channels (C l ) is larger than the hydraulic diameter (D h ) of the internal channels, wherein the hydraulic diameter is D h =4 A/p, where A is the cross-section area of the channel and p is the perimeter of said cross-section, and   wherein at least one curved wall segment ( 1 . 2 ) comprises a deformed portion ( 1 . 2 . 1 ), with a configuration of the deformed portion ( 1 . 2 . 1 ) penetrating into the lateral channel (C l ) reducing the section thereof.   
     
     
         2 . Tube ( 1 ) according to  claim 1 , wherein the deformed segment ( 1 . 2 . 1 ) is spaced from both ends according to the longitudinal direction (X-X′). 
     
     
         3 . Tube ( 1 ) according to  claim 1 , wherein the set of fins ( 1 . 3 ) is formed by a sheet corrugated by stamping, with the direction of the corrugation being in accordance with a direction perpendicular to the longitudinal direction (X-X′) and parallel to the flat walls ( 1 . 1 ). 
     
     
         4 . Tube ( 1 ) according to  claim 1 , wherein the corrugated sheet additionally shows a second corrugation according to the longitudinal direction (X-X′). 
     
     
         5 . Tube ( 1 ) according to  claim 1 , wherein the position of the deformed portion ( 1 . 2 . 1 ) according to the longitudinal direction (X-X′) is at a point of minimum distance between the corrugation and the inner wall of a curved wall segment ( 1 . 2 ). 
     
     
         6 . Tube ( 1 ) according to  claim 1 , wherein the deformed portion ( 1 . 2 . 1 ) is spaced from the set of fins ( 1 . 3 ). 
     
     
         7 . Tube ( 1 ) according to  claim 1 , wherein the deformed portion ( 1 . 2 . 1 ) shows, according to a projection in a plane parallel to the flat walls ( 1 . 1 ), an arc configuration, wherein the arc has a minimum ratio between the radius of curvature and thickness which is in the range [13-20], more preferably in the range [14-19], more preferably in the range [15, 18], more preferably in the range [16-17.5] and more preferably in the range [16.1-17.2]. 
     
     
         8 . Tube ( 1 ) according to  claim 1 , wherein the deformed portion ( 1 . 2 . 1 ) shows, according to a projection in a plane parallel to the flat walls ( 1 . 1 ), an arc configuration, wherein at least one end of the arc, in the transition thereof with the surface of the lateral channel (C l ), has a minimum ratio between the radius of curvature and thickness which is in the range [0.9-3.1], more preferably in the range [1-3] and more preferably in the range [1.25-2.75]. 
     
     
         9 . Tube ( 1 ) according to  claim 1 , wherein the deformed portion ( 1 . 2 . 1 ) shows, according to a section by means of a perpendicular plane of section, the longitudinal direction (X-X′) and a central position of the deformed portion ( 1 . 2 . 1 ), a minimum ratio between the radius of curvature and thickness which is in the range [0.9-3.1], more preferably in the range [1-3] and more preferably in the range [1.25-2.75]. 
     
     
         10 . Method of manufacturing a tube ( 1 ) comprising the following steps:
 a) providing a tube ( 1 ) having a flat configuration, configured by means of two essentially parallel flat walls ( 1 . 1 ) extending along a longitudinal direction (X-X′) and joined on both sides by means of a curved wall segment ( 1 . 2 );   b) inserting into the tube ( 1 ) a set of fins ( 1 . 3 ) leaving a lateral channel (C l ) between the set of fins ( 1 . 3 ) and each curved wall segment ( 1 . 2 );   c) pressing the curved wall segment ( 1 . 2 ) in a region of its outer surface causing a deformed portion ( 1 . 2 . 1 ) which narrows the section of the lateral channel (C l );   d) attaching the set of fins ( 1 . 3 ) to the tube ( 1 ), preferably by brazing.