Method of making an improved heat transfer tube with grooved inner surface

Abstract

A method of making an improved heat transfer tube. The inner surface of the tube has a primary set of fins and an intermediate sets of fins positioned in the areas between the primary fins and at an angle relative to the primary fins. While intermediate fins may be used with primary fins arranged in any pattern, in a preferred embodiment of the inner surface tube design, the intermediate fins are positioned relative to the primary fins to result in a grid-like appearance. Tests show that the performance of tubes having the intermediate fin designs of the present invention is significantly enhanced. A first set of rollers creates the primary and intermediate fin designs on at least one side of a board. A second set of rollers may be used to further enhance the performance. After the desired pattern has been transferred onto the board with the rollers, the board is then formed and welded into a tube, so that, at a minimum, the inner surface design of the resulting tube includes the intermediate fins as contemplated by the present invention.

We claim:  
     
         1 . A method of manufacturing a tube comprising forming a pattern along an inner surface of the tube, wherein the pattern comprises a plurality of primary fins, a plurality of intermediate fins, and a plurality of grooves defined by adjacent primary fins, wherein the plurality of intermediate fins are positioned in at least some of the plurality of grooves.  
     
     
         2 . A method of manufacturing a tube comprising: 
 a. a rolling step of running a board under a fin forming roller so as to roll a pattern of fins onto a surface of the board, wherein the pattern of fins t comprises a plurality of primary fins, a plurality of intermediate fins, and a plurality of grooves defined by adjacent primary fins, wherein the plurality of intermediate fins are positioned in at least some of the plurality of grooves;    b. a tube forming step of passing the board onto which the pattern of fins has been formed through at least one forming roller to form the board into a desired tube shape with the pattern positioned on the inside; and    c. a board securing step to secure the board in the desired tube shape.    
     
     
         3 . The method of  claim 2 , wherein the board securing step comprises a welding step of heating both side edges of the board which has been formed into a tube shape and adjoining the side edges of the board.  
     
     
         4 . A method of manufacturing a tube comprising: 
 a. running a board having a length under a channel forming roller to form at least one channel on a surface of the board and along at least a portion of the length of the board;    b. running the board having the at least one channel under a fin forming roller to roll a pattern of fins onto the surface of the board, wherein the pattern of fins comprises a plurality of primary fins, a plurality of intermediate fins, and a plurality of grooves defined by adjacent primary fins, wherein the plurality of intermediate fins are positioned in at least some of the plurality of grooves;    c. passing the board onto which the at least one channel and pattern of fins has been formed through at least one tube forming roller to form the board into a desired tube shape with the at least one channel and the pattern positioned on the inside; and    d. securing the board in the desired tube shape.