Method for Manufacturing Tube and Fin Heat Exchanger with Reduced Tube Diameter and Optimized Fin Produced Thereby

Abstract

An improved method for manufacturing tube and fin heat exchangers that, according to a preferred embodiment, includes a process for increasing the stiffness and rigidity of heat exchanger fins. Stiffer fins have a greater tendency to maintain proper alignment within a stack of fins, which aids in lacing long stacks of fins with small (e.g., 5 mm) diameter tubing. Preferably, fin stiffness is increased by forming a plurality of longitudinal ribs within the fin during the fin stamping process. More preferably still, two ribs for each longitudinal row of collared holes are provided. The preferred embodiment also includes a slotted heat exchanger fin that is dimensioned and arranged for optimized thermodynamic performance when used with small diameter tubing, thus reducing the space required for a given heat exchanger system.

1 . A fin ( 12 ′) for a tube and fin heat exchanger ( 10 ) comprising:
 a generally planar metallic sheet;   a first plurality of apertures ( 18 ′) formed through said sheet and defining a first longitudinal row of apertures ( 18 ′); and   first and second longitudinal ribs ( 100 ) formed in said sheet, said first longitudinal row of apertures ( 18 ′) disposed between said first and second longitudinal ribs ( 100 );   said first and second ribs ( 100 ) each having a top surface projecting beyond the upper surface ( 103 ) defined by said sheet.   
     
     
         2 . The fin ( 12 ′) of  claim 1  further comprising:
 a second plurality of apertures ( 18 ′) formed through said sheet and defining a second longitudinal row of apertures ( 18 ′); and   third and fourth longitudinal ribs ( 100 ) formed in said sheet, said second longitudinal row of apertures ( 18 ′) disposed between said third and fourth longitudinal ribs ( 100 ), said second and third longitudinal ribs ( 100 ) disposed between said first and second longitudinal lows of apertures ( 18 ′).   
     
     
         3 . The fin ( 12 ′) of  claim 1  further comprising:
 a plurality of raised vanes ( 112 ) forming a generally ‘X’-shaped pattern ( 105 ) in said sheet between first and second apertures ( 18 ′) of said first plurality of apertures ( 18 ′);   each of said plurality of raised vanes ( 112 ) formed between first and second longitudinal slits ( 110 ) in said sheet such that an opening ( 114 ) is defined between said raised vane ( 112 ) and the surface ( 103 ) of said sheet.   
     
     
         4 . The fin ( 12 ′) of  claim 3  wherein:
 said plurality of raised vanes ( 112 ) are arranged in first, second, third, fourth and fifth rows ( 120 ,  122 ,  124 ,  126 ,  128 ) parallel to said first longitudinal rib ( 100 ).   
     
     
         5 . The fin ( 12 ′) of  claim 3  wherein:
 at least one of said plurality of raised vanes ( 112 ) is attached to the sheet at a first end ( 113 );   said first end ( 113 ) is oriented at an angle (α) from an imaginary line that is perpendicular to said first longitudinal rib ( 100 ); and   said angle (α) is between 15 and 45 degrees.   
     
     
         6 . The fin ( 12 ′) of  claim 5  wherein:
 said at least one of said plurality of raised vanes ( 112 ) is attached to the sheet at a second end ( 113 );   said first and second ends ( 113 ) are oriented at said angle (α) from an imaginary line that is perpendicular to said first longitudinal rib ( 100 ); and   said angle (α) is between 25 and 35 degrees.   
     
     
         7 . The fin ( 12 ′) of  claim 1  further comprising:
 nine raised vanes ( 112 ) forming a generally ‘X’-shaped pattern ( 105 ) in said sheet between first and second apertures ( 18 ′) of said first plurality of apertures ( 18 ′);   each of said nine raised vanes ( 112 ) formed between first and second longitudinal slits ( 110 ) in said sheet such that an opening ( 114 ) is defined between said raised vane ( 112 ) and the surface ( 103 ) of said sheet;   wherein first and second vanes ( 112 ) of said nine raised vanes ( 112 ) are disposed in a first row ( 120 ) of vanes ( 112 ) that is parallel to said first rib ( 100 ), third and fourth vanes ( 112 ) of said nine raised vanes ( 112 ) are disposed in a second row ( 122 ) of vanes ( 112 ) that is parallel to said first rib ( 100 ), a fifth vane ( 112 ) of said nine raised vanes ( 112 ) is disposed in a third row ( 124 ) of vanes ( 112 ) that is parallel to said first rib ( 100 ), said second row ( 122 ) of vanes ( 112 ) is disposed adjacent to and between said first and third rows ( 120 ,  124 ) of vanes ( 112 ), sixth and seventh vanes ( 112 ) of said nine raised vanes ( 112 ) are disposed in a fourth row ( 126 ) of vanes ( 112 ) that is parallel to said first rib ( 100 ), said third row ( 124 ) of vanes ( 112 ) is disposed adjacent to and between said second and fourth rows ( 122 ,  126 ) of vanes ( 112 ), eighth and ninth vanes ( 112 ) of said nine raised vanes ( 112 ) are disposed in a fifth row ( 128 ) of vanes ( 112 ) that is parallel to said first rib ( 100 ), and said fourth row ( 126 ) of vanes ( 112 ) is disposed adjacent to and between said third and fifth rows ( 124 ,  128 ) of vanes ( 112 ).   
     
     
         8 . The fin ( 12 ′) of  claim 3  wherein:
 each of said plurality of raised vanes ( 112 ) has a depth dimension (d v ) from said first slit ( 110 ) to said second slit ( 110 ) between 0.5 and 1.5 millimeters.   
     
     
         9 . The fin ( 12 ′) of  claim 3  wherein.
 each of said plurality of raised vanes ( 112 ) has a height dimension (h v ) from said upper surface ( 103 ) of said sheet to said top surface of said vane ( 112 ) between 0.25 and 0.75 millimeters.   
     
     
         10 . The fin ( 12 ′) of  claim 1  wherein:
 each of said ribs ( 100 ) has a height dimension (h r ) from said upper surface ( 103 ) of said sheet to the top surface of said rib ( 100 ) between 0.05 and 0.25 millimeters.   
     
     
         11 . The fin ( 12 ′) of  claim 1  wherein:
 the longitudinal distance (p w ) between the centers of two adjacent apertures ( 18 ′) of said first plurality of apertures ( 18 ′) in said first longitudinal row of apertures ( 18 ′) is between 12 and 18 millimeters.   
     
     
         12 . The fin ( 12 ′) of  claim 2  wherein:
 the perpendicular distance (p t ) between the center of said first longitudinal row of apertures ( 18 ′) and the center of the second longitudinal row of apertures ( 18 ′) is between 10 and 15 millimeters.   
     
     
         13 . A fin ( 12 ′) for a tube and fin heat exchanger ( 10 ) comprising:
 a generally planar metallic sheet;   a first plurality of apertures ( 18 ′) formed through said sheet and defining a first longitudinal row of apertures ( 18 ′); and   a plurality of raised vanes ( 112 ) forming a generally ‘X’-shaped pattern ( 105 ) in said sheet between first and second apertures ( 18 ′) of said first plurality of apertures ( 18 ′);   each of said plurality of raised vanes ( 112 ) formed between first and second parallel slits ( 110 ) in said sheet such that an opening ( 114 ) is defined between said raised vane ( 112 ) and the surface ( 103 ) of said sheet.   
     
     
         14 . The fin ( 12 ′) of  claim 13  wherein:
 first and second vanes ( 112 ) of said plurality of raised vanes ( 112 ) are disposed in a first row ( 120 ) of vanes ( 112 ) that is parallel to said first longitudinal row of apertures ( 18 ′);   third and fourth vanes ( 112 ) of said plurality of raised vanes ( 112 ) are disposed in a second row ( 122 ) of vanes ( 112 ) that is parallel to said first longitudinal row of apertures ( 18 ′);   a fifth vane ( 112 ) of said plurality of raised vanes ( 112 ) is disposed in a third row ( 124 ) of vanes ( 112 ) that is parallel to said first longitudinal row of apertures ( 18 ′);   sixth and seventh vanes ( 112 ) of said plurality of raised vanes ( 112 ) are disposed in a fourth row ( 126 ) of vanes ( 112 ) that is parallel to said first longitudinal row of apertures ( 18 ′);   eighth and ninth vanes ( 112 ) of said plurality of raised vanes ( 112 ) are disposed in a fifth row ( 128 ) of vanes ( 112 ) that is parallel to said first longitudinal row of apertures ( 18 ′);   said second row ( 122 ) of vanes ( 112 ) is disposed adjacent to and between said first and third rows ( 120 ,  122 ) of vanes ( 112 );   said third row ( 124 ) of vanes ( 112 ) is disposed adjacent to and between said second and fourth rows ( 122 ,  126 ) of vanes ( 112 ); and   said fourth row ( 126 ) of vanes ( 112 ) is disposed adjacent to and between said third and fifth rows ( 124 ,  128 ) of vanes ( 112 ).   
     
     
         15 . The fin ( 12 ′) of  claim 14  wherein:
 said first, second, third, fourth, sixth, seventh. eight, and ninth vanes ( 112 ) of said plurality of raised vanes ( 112 ) each have first and second distal ends ( 113 ) connected to said sheet, each of said distal ends ( 113 ) being oriented at an angle (α) between 15 and 45 degrees from an imaginary line that is perpendicular to said first longitudinal row of apertures ( 18 ′).   
     
     
         16 . A tube and fin heat exchanger ( 10 ) comprising:
 a plurality of fins ( 12 ′) arranged in a stack, each of said plurality of fins ( 12 ′) characterized by a generally planar metallic sheet, a first plurality of apertures ( 18 ′) formed through said sheet and defining a first longitudinal row of apertures ( 18 ′), and first and second longitudinal ribs ( 100 ) formed in said sheet, said first longitudinal row of apertures ( 18 ′) disposed between said first and second longitudinal ribs ( 100 ), said first and second ribs ( 100 ) each having a top surface projecting beyond the upper surface ( 103 ) defined by said sheet; and   a tube ( 22 ) received through said stack and in physical contact with each of said plurality of fins ( 12 ′).   
     
     
         17 . A tube and fin heat exchanger ( 10 ) comprising:
 a plurality of fins ( 12 ′) arranged in a stack, each of said plurality of fins ( 12 ′) characterized by a generally planar metallic sheet, a first plurality of apertures ( 18 ′) formed through said sheet and defining a first longitudinal row of apertures ( 18 ′), and a plurality of raised vanes ( 112 ) forming a generally ‘X’-shaped pattern ( 105 ) in said sheet between first and second apertures ( 18 ′) of said first plurality of apertures ( 18 ′), each of said plurality of raised vanes ( 112 ) formed between first and second parallel slits ( 110 ) in said sheet such that an opening ( 114 ) is defined between said raised vane ( 112 ) and the surface ( 103 ) of said sheet; and   a tube ( 22 ) received through said stack and in physical contact with each of said plurality of fins ( 12 ′).