Heat exchange device and method

Abstract

A heat exchange device comprising a fluid flow passage having a plurality of successive segments in fluid flow communication with one another, the segments being adapted to maintain a developing flow therein and thereby improve heat transfer.

1 . A heat exchange device comprising a body defining at least one tortuous passage adapted to direct a heat transfer fluid therethrough, said passage having at least a plurality of successive segments in serial fluid flow communication, each of said segments having a length less than a length required for said fluid to achieve a fully developed laminar flow therein, thereby increasing convective heat transfer efficiency by causing a pipe inlet effect throughout said fluid flow passage.  
   
   
       2 . The heat exchange device as defined in  claim 1 , wherein said body is a current-carrying winding of an electric machine.  
   
   
       3 . The heat exchange device as defined in  claim 1 , wherein said body is a heat sink plate for an electronic device.  
   
   
       4 . The heat exchange device as defined in  claim 1 , wherein said successive segments have varying lengths relative to one another.  
   
   
       5 . The heat exchange device as defined in  claim 1 , wherein said segment length is less than three-quarters of said length required for said fluid to achieve a fully developed laminar flow in said segment.  
   
   
       6 . The heat exchange device as defined in  claim 1 , wherein said segment length is less than half of said length required for said fluid to achieve a fully laminar flow in said segment.  
   
   
       7 . The heat exchange device as defined in  claim 1 , wherein said segment length is less than one-quarter of said length required for said fluid to achieve a fully laminar flow in said segment.  
   
   
       8 . A method of improving heat transfer between a body and a fluid passing through a passage and adjacent the body, the method comprising the steps of: 
 determining a threshold segment geometry, said threshold segment geometry including at least a passage length required for said fluid travelling through said passage to become fully developed laminar flow therein;    providing said passage adjacent the body, the passage having a plurality of segments in serial fluid flow communication, each segment having geometry relative to said threshold segment geometry such that fluid passing through said segment cannot become fully developed laminar flow; and    directing said fluid through said passage such that a developing flow is maintained in said segments.    
   
   
       9 . The method as defined in  claim 8 , wherein said passage is defined in said body.  
   
   
       10 . A method of improving heat transfer between a body and a fluid passing through a passage adjacent the body, the method comprising the steps of: 
 selecting a passage geometry having a plurality of successive segments, the passage geometry selected relative to the fluid to provide a desired Nusselt number for each of said successive segments, wherein said desired Nusselt is provided in a range between a Nusselt number corresponding to an inlet flow into the segment and a Nusselt number corresponding to a fully developed laminar flow in the segment;    providing a passage comprised of said passage geometry; and    directing the fluid through the passage.    
   
   
       11 . The method as defined in  claim 10 , wherein the desired Nusselt number is at least three-quarters of said a Nusselt number corresponding to an inlet flow into the segment.  
   
   
       12 . The method as defined in  claim 10 , further comprising the step of defining the passage inside the body.  
   
   
       13 . The method as defined in  claim 10 , wherein the step of selecting a passage geometry includes the step of determining a substantially constant effective diameter for each segment, and then determining a segment length for each segment.  
   
   
       14 . The method as defined in  claim 10 , wherein the step of selecting a passage geometry includes the step of arranging successive segments at an angle of less than 180 degrees relative to one another.  
   
   
       15 . The method as defined in  claim 10 , wherein the step of selecting a passage geometry includes the step of minimizing segment length to thereby maximize segment Nusselt number.  
   
   
       16 . A heat exchange device comprising a body including at least one passage adapted to direct a heat transfer fluid therethrough and adjacent the body, said passage including a plurality of successive segments in serial fluid flow communication with one another, in use each of said segments adapted to maintain the heat transfer fluid in a developing flow state when directed therethrough, wherein the segments are so adapted by reason of their respective geometries relative to one another.  
   
   
       17 . The heat exchange device as defined in  claim 16 , wherein the respective geometries include a segment length and wherein segment length is less than a length required for the heat transfer fluid to become fully developed laminar flow in the segment.  
   
   
       18 . The heat exchange device as defined in  claim 17 , wherein the segment length of a segment is different than that of an immediately successive segment.  
   
   
       19 . The heat exchange device as defined in  17 , wherein the respective geometries further include immediately successive segments angled substantially perpendicular relative to one another.  
   
   
       20 . The heat exchange device as defined in  claim 16 , wherein the passage is at least partially defined inside the body.