Evaporator with aerodynamic first dimples to suppress whistling noise

Abstract

A heat exchanger assembly including a plurality of pairs of plates disposed in series for fluid flow from a pass through one pair of plates to a pass through the next pair of plates. Each pair of plates includes a central rib to define a U-shaped passage having a fluid entering leg and a fluid exiting leg interconnected by an open bottom interconnecting the legs below the lower end of the engaging ribs. A plurality of first dimples project into the passage to interact with fluid flow through the passage and each of the first dimples has an aerodynamic, e.g., tear-drop, shape to reduce whistling noise in the latter pairs of plates.

1 . A heat exchanger assembly comprising; 
 at least one pair of plates having mating edges and a concave region delimited by said edges to define a fluid passage,    said plates having tubular projections defining an inlet for entering fluid to said passage and an outlet for exiting fluid from said passage to thereby establish a direction of fluid flow,    a plurality of first dimples projecting into said passage to interact with fluid flow through said passage, and    characterized by each of said first dimples having an aerodynamic shape including a large bulbous leading portion extending into a longer and tapering trailing portion with said leading portion being disposed into the fluid flow from said inlet to said outlet.    
   
   
       2 . An assembly as set forth in  claim 1  wherein said aerodynamic shape of each of said first dimples is tear-drop shaped.  
   
   
       3 . An assembly as set forth in  claim 1  including a plurality of pairs of said plates disposed in series for fluid flow from a pass through one pair of plates to a pass through the next pair of plates.  
   
   
       4 . An assembly as set forth in  claim 3  wherein said first dimples are disposed in at least a selected section of said pair of plates defining the last pass.  
   
   
       5 . An assembly as set forth in  claim 3  wherein said first dimples are disposed in at least the last two pair of plates defining the last two passes.  
   
   
       6 . An assembly as set forth in  claim 3  wherein said first dimples are disposed in a first section and combined with a plurality of second dimples having different shapes in said pair of plates defining the last pass.  
   
   
       7 . An assembly as set forth in  claim 3  wherein each first dimple has an axis A and extends equally on either side of and along said axis A, each axis A being disposed at an acute angle Φ from said direction of fluid flow.  
   
   
       8 . An assembly as set forth in  claim 7  wherein said first dimples are disposed in overlapping relationship in said direction of fluid flow.  
   
   
       9 . An assembly as set forth in  claim 3  wherein each of said pair of plates includes a central rib to define a U-shaped passage having a fluid entering leg and a fluid exiting leg interconnected by an open bottom.  
   
   
       10 . An assembly as set forth in  claim 9  wherein said first dimples are disposed in said legs and not in said bottom of said U-shaped passage.  
   
   
       11 . An assembly as set forth in  claim 9  wherein each first dimple has an axis A and extends equally on either side of and along said axis A, each axis A being disposed at an acute angle Φ from said direction of fluid flow.  
   
   
       12 . An assembly as set forth in  claim 11  wherein said first dimples are disposed in overlapping relationship in said direction of fluid flow.  
   
   
       13 . An assembly as set forth in  claim 3  wherein said first dimples are disposed in a first section and combined with a plurality of second dimples having different shapes in said pair of plates defining the last pass, and including air-fins disposed between adjacent pairs of plates for enhancing heat exchange between air flowing through said fins and fluid flow through said passage defined by each pair of plates.