Finned tube heat exchanger

Abstract

A heat exchanger comprises a tube and fins extending from an outer surface of the tube. The fins comprise first and second sets of fins with the first set of fins oriented in a first direction with respect to an axial direction of the tube and the second set of fins oriented in a second direction with respect to the axial direction of the tube to expose at least a portion of the first and second sets of fins to a free stream.

1 . A heat exchanger, comprising:
 a tube; and   fins extending from an outer surface of the tube, the fins comprise first and second sets of fins with the first set of fins oriented in a first direction with respect to an axial direction of the tube and the second set of fins oriented in a second direction with respect to the axial direction of the tube to expose at least a portion of the first and second sets of fins to a free stream.   
     
     
         2 . The heat exchanger of  claim 1 , wherein the first and second sets of fins are alternately arranged to expose each of the fins to the free stream. 
     
     
         3 . The heat exchanger of  claim 1 , wherein the fins are arranged in a helical path around the outer surface of the tube. 
     
     
         4 . The heat exchanger of  claim 3 , wherein the first direction is in line with the helical path and the second direction is at an angle with respect to the helical path. 
     
     
         5 . The heat exchanger of  claim 3 , wherein the first direction and the second direction are at an angle with respect to the helical path. 
     
     
         6 . The heat exchanger of  claim 1 , wherein the fins are formed by creating slits on a fin strip and bending the first set of fins, the second set of fins, or both the first and second sets of fins with respect to the fin strip before helically winding and attaching the fin strip on the outer surface of the tube. 
     
     
         7 . A heat exchanger, comprising:
 a tube; and   fins extending from an outer surface of the tube, the fins comprise groups of contiguous fins that are oriented alternately in first and second directions with respect to an axial direction of the tube to expose the groups of contiguous fins to a free stream.   
     
     
         8 . The heat exchanger of  claim 7 , wherein the fins are arranged in a helical path around the outer surface of the tube. 
     
     
         9 . The heat exchanger of  claim 8 , wherein the first direction is in line with the helical path and the second direction is at an angle with respect to the helical path. 
     
     
         10 . The heat exchanger of  claim 8 , wherein the first direction and the second direction are at an angle with respect to the helical path. 
     
     
         11 . The heat exchanger of  claim 7 , wherein the fins are formed by creating slits on a fin strip and bending a portion of fins with respect to the fin strip to correspond to the first and second directions before helically winding and attaching the fin strip on the outer surface of the tube. 
     
     
         12 . A heat exchanger, comprising:
 a tube; and   fins extending from an outer surface of the tube in a helical path, the fins comprise serrated sections and solid sections that are disposed in a predetermined arrangement along the helical path.   
     
     
         13 . The heat exchanger of  claim 12 , wherein the serrated sections and the solid sections are alternately disposed along the helical path. 
     
     
         14 . The heat exchanger of  claim 12 , wherein a portion of the serrated sections are directly in the path of a free stream. 
     
     
         15 . The heat exchanger of  claim 12 , wherein a portion of the solid sections are directly in the path of a free stream. 
     
     
         16 . The heat exchanger of  claim 12 , wherein the solid sections comprise groove, dimples, corrugations, or other heat transfer enhancing features. 
     
     
         17 . The heat exchanger of  claim 12 , wherein each of the serrated sections includes a plurality of individual fins that extend substantially till the outer surface of the tube. 
     
     
         18 . The heat exchanger of  claim 17 , wherein the fins comprise a fin strip that is helically wound and attached to the outer surface of the tube, with slits created on the fin strip corresponding to the serrated sections before helically winding the fin strip. 
     
     
         19 . A heat exchanger, comprising:
 a tube; and   fins extending from an outer surface of the tube in a helical path, the fins comprise serrated sections and solid sections that are alternately disposed along the helical path, wherein the tube is positioned such that a portion of either the serrated sections or the solid sections are directly in the path of a free stream.   
     
     
         20 . The heat exchanger of  claim 19 , wherein the solid sections comprise groove, dimples, corrugations, or other heat transfer enhancing features. 
     
     
         21 . The heat exchanger of  claim 19 , wherein each of the serrated sections includes a plurality of individual fins that extend substantially till the outer surface of the tube. 
     
     
         22 . The heat exchanger of  claim 21 , wherein the fins comprise a fin strip that is helically wound and attached to the outer surface of the tube, with slits created on the fin strip corresponding to the serrated sections before helically winding the fin strip.