Louvered fins for heat exchanger

Abstract

The invention concerns a louvered fin comprising an assembly of wave stems ( 123 ) alternately linked by a wave crest ( 121 ) and a wave base ( 122 ), and wherein the wave stems ( 123 ) are provided with flaps ( 125 ) cut out in said wave stems ( 123 ) and sloping at angle relative to the main undulating direction (D 1 ). The wave stems ( 123 ), crests ( 121 ) and bases ( 122 ) form, in cross-section relative to the main undulating direction (D 1 ), rectilinear segments, the crests and the bases being mutually parallel.

1 . A corrugated fin for a plate and fin heat exchanger, of the type with louvers defining an overall main direction of corrugation (D 1 ), comprising a set of corrugation legs ( 123 ) alternately connected by a corrugation crest ( 121 ) and by a corrugation trough ( 122 ), the corrugation legs ( 123 ) being provided with flaps ( 125 ) cut from said corrugation legs ( 123 ) and inclined at an angle (α) with respect to the main direction of corrugation (D 1 ), characterized in that the corrugation legs ( 123 ), the corrugation crests ( 121 ) and the corrugation troughs ( 122 ) form, in cross section with respect to the main direction of corrugation (D 1 ), straight segments, the crests ( 121 ) and the troughs ( 122 ) being mutually parallel.  
     
     
         2 . The corrugated fin as claimed in  claim 1 , characterized in that the corrugation legs ( 123 ) are all mutually parallel and perpendicular to the corrugation troughs ( 122 ), so that the fin has a square wave-shaped corrugation.  
     
     
         3 . The corrugated fin as claimed in  claim 1  or  2 , characterized in that each flap ( 12 ) is cut along the direction of the straight segment defined by the corrugation leg ( 123 ) over substantially the entire length of said segment.  
     
     
         4 . The corrugated fin as claimed in any one of  claims 1  to  3 , characterized in that the fin has a substantially uniform wall thickness (e) of between 0.2 and 0.5 mm.  
     
     
         5 . The corrugated fin as claimed in any one of  claims 1  to  4 , in which the corrugation legs ( 123 ) have a thickness (e), a mean transverse separation (w) with respect to the overall main direction of corrugation (D 1 ), which defines the width of a passage channel and a spacing (p), and the flaps ( 125 ) have a length (l s ), characterized in that the length (l s ) is greater than the spacing (p).  
     
     
         6 . The corrugated fin as claimed in  claim 5 , characterized in that the length (l s ) of the flaps satisfies the following relationship: 
 l s ≧1.1p.    
     
     
         7 . The corrugated fin as claimed in  claim 5  or  6 , characterized in that the angle of inclination of the flaps (α) lies, in terms of absolute value, strictly between a minimum value (α min ) and a maximum value (α max ) which are positive and defined by the following equations: 
 sin α min =e/l s    
 and  
           tan                   α   max       =     p     1   s                       
 
     
     
         8 . The corrugated fin as claimed in any one of  claims 5  to  7 , characterized in that the angle of inclination (α) of the flaps ( 25 ) is substantially equal, in terms of absolute value, to an angle (α 1 ) defined by the equation:  
       
         
           
             
               
                 tan 
                  
                 
                     
                 
                  
                 
                   α 
                   1 
                 
               
               = 
               
                 p 
                 
                   21 
                   s 
                 
               
             
           
           
           
               
           
         
       
     
     
         9 . The corrugated fin as claimed in any one of  claims 5  to  7 , characterized in that the angle of inclination (α) of the flaps ( 125 ) meets the condition: 
 p≧l s  sin|α|+e cos|α|.  
 
     
     
         10 . A plate and fin heat exchanger of a unit for separating air or H 2 /CO mixtures by cryogenic distillation, particularly an exchanger of a main heat exchange line or a reboiler/condenser, of the type comprising a stack of parallel plates ( 2 ) which define a plurality of fluid-circulation passages ( 3  to  5 ) of flat overall shape, closure bars ( 6 ) delimiting these passages, and corrugated fins ( 8 ) arranged in the passages, characterized in that at least some of the corrugated fins ( 8 ) are as claimed in any one of  claims 1  to  9 .  
     
     
         11 . A method for the continuous manufacture, from a flat product in sheet form, of a louvered corrugated fin for a plate heat exchanger, of the type comprising flaps ( 25 ;  125 ) cut from corrugation legs ( 23 ;  123 ), in which the product ( 205 ) is passed step by step through a press tool ( 201 ,  202 ) comprising at least a moving tool part ( 201 ) with a reciprocating movement, said tool part ( 201 ) in the one same movement corrugating the fin and cutting the flaps.  
     
     
         12 . The corrugated fin as claimed in  claim 11 , characterized in that the flat product ( 205 ) is held in position upstream of said moving tool part ( 201 ) by means of a holding device ( 210 ) when said moving tool part ( 201 ) is active, and the flat product ( 205 ) is released to continue its journey and to extract the formed corrugation from the tool when the moving tool part ( 201 ) is inactive.  
     
     
         13 . The corrugated fin as claimed in  claim 12 , characterized in that the holding device ( 210 ) and the moving tool part ( 201 ) are driven and synchronized by command and control means ( 220 ).  
     
     
         14 . A device for implementing the method as claimed in any one of  claims 11  to  13 , comprising a press tool ( 201 ,  202 ), a device for continuously feeding the tool with flat product in sheet form ( 205 ), said tool comprising at least one punch ( 202 ) and one die ( 201 ) that complement each other, said punch ( 202 ) being able to be given a relative translational movement with respect to the die ( 202 ) in a direction substantially orthogonal to the surface of the flat product in sheet form ( 205 ), characterized in that said punch ( 202 ) extends in a longitudinal overall direction (D) and has a plurality of planar facets of which at least one ( 251 ) is directed in the direction of translation of the punch and said overall direction (D) and at least another ( 252 ), intended to form a flap, is directed in the direction of translation of the punch and a direction inclined with respect to the overall direction (D).  
     
     
         15 . The device as claimed in  claim 14 , characterized in that the punch ( 202 ) comprises, between two consecutive facets, a planar setback ( 253 ) in the direction of translation and a direction substantially orthogonal to the overall direction (D).  
     
     
         16 . The device as claimed in  claim 15 , characterized in that the punch ( 202 ) has grooves ( 255 ) running in the direction of translation, between a facet ( 251 ,  252 ) and a setback ( 253 ).  
     
     
         17 . The device as claimed in  claim 16 , characterized in that it comprises a device ( 210 ) for holding the flat product in sheet form ( 205 ) upstream of the tool ( 201 ,  202 ) allowing the flat product selectively to be fixed with respect to the tool or released to allow it to progress.  
     
     
         18 . The device as claimed in  claim 17 , characterized in that it comprises command and control means ( 220 ) designed to drive and synchronize the tool ( 201 ,  202 ) and the holding device ( 210 ).