Heat exchanger

Abstract

A heat exchanger is provided having two headers with a plurality of elongate tubes extending between the headers, where the tubes cooperate with an array of fins. The tubes have a plurality of dimpled sections having a non-uniform dimple density alternating with a plurality of smooth sections. The alternating dimpled and smooth sections allow heat to effectively transfer from a liquid coolant flowing through the tubes into the tube walls and fins at laminar, transitional, and turbulent flow conditions.

What is claimed is: 
     
         1 . A heat exchanger comprising:
 first and second headers having a plurality of elongate tubes extending there between, the tubes cooperating with an array of fins,   wherein the tubes have a plurality of dimpled sections having a non-uniform dimple density followed by one of a plurality of alternating smooth sections, in order to effectively transfer heat between a liquid flowing through each tube and a tube wall at laminar, transitional, and turbulent flow conditions.   
     
     
         2 . The heat exchanger of  claim 1 , wherein the dimpled sections have a first end and a second end, and the density of the dimples gradually decreases along a longitudinal direction moving from the first end to the second end in the direction of liquid flow. 
     
     
         3 . The heat exchanging tube of  claim 1 , wherein each of the tubes have at least three dimpled sections and at least three smooth sections. 
     
     
         4 . The heat exchanger of  claim 1 , wherein the dimples within the dimpled sections are arranged in a plurality of clusters. 
     
     
         5 . The heat exchanger of  claim 1 , wherein the plurality of elongate tubes are made from aluminum. 
     
     
         6 . The heat exchanger of  claim 1 , further comprising two header tanks that are fixed to the first and second headers, wherein the header tanks collect the liquid that flows through the plurality of elongate tubes. 
     
     
         7 . The heat exchanger of  claim 6 , wherein the header tanks are made from plastic. 
     
     
         8 . The heat exchanger of  claim 6 , wherein the header tanks are made from aluminum. 
     
     
         9 . The heat exchanger of  claim 1 , wherein the liquid flows into the heat exchanger at the first header, through the plurality of tubes, and out of the heat exchanger at the second header. 
     
     
         10 . The heat exchanger of  claim 1 , wherein the dimpled sections have a length L that ranges between 10 mm and 200 mm. 
     
     
         11 . The heat exchanger of  claim 1 , wherein the smooth sections have a length M that ranges between 10 mm and 200 mm. 
     
     
         12 . A heat exchanger comprising:
 first and second headers having a plurality of elongate tubes extending there between, the tubes cooperating with an array of fins; and   first and second header tanks having ports, attached to the first and second headers for collecting a liquid flowing into and out of the heat exchanger,   wherein the tubes have a plurality of dimpled sections having a non-uniform dimple density followed by one of a plurality of alternating smooth sections, in order to effectively transfer heat between the liquid flowing through each tube and a tube wall at laminar, transitional, and turbulent flow conditions.   
     
     
         13 . The heat exchanger of  claim 12 , wherein the dimpled sections have a first end and a second end, and the density of the dimples gradually decreases along a longitudinal direction moving from the first end to the second end in the direction of liquid flow. 
     
     
         14 . The heat exchanger of  claim 12 , wherein each of the tubes have at least three dimpled sections and at least three smooth sections. 
     
     
         15 . The heat exchanger of  claim 12 , wherein the dimples within the dimpled sections are arranged in a plurality of clusters. 
     
     
         16 . The heat exchanger of  claim 12 , wherein the plurality of elongate tubes are made from aluminum. 
     
     
         17 . The heat exchanger of  claim 12 , wherein the header tanks are made from plastic. 
     
     
         18 . The heat exchanger of  claim 12 , wherein the header tanks are made from aluminum. 
     
     
         19 . The heat exchanger of  claim 12 , wherein the dimpled sections have a length L that ranges between 10 mm and 200 mm. 
     
     
         20 . The heat exchanger of  claim 12 , wherein the smooth sections have a length M that ranges between 10 mm and 200 mm.