Heat exchange tube having increased heat transfer area

Abstract

The heat exchange tubes of the invention are provided with an inner wall having an increased surface area for contact with a fluid circulating through the tube for the greater exchange of heat energy between the circulating fluid and an external fluid. The outer wall of the heat exchange tube is provided with a series of radially outwardly extending members for increasing the heat exchange surface of the outer wall of the tube.

Having defined the invention I claim:  
     
         1 . A heat exchange tube defining a bore for the circulation of a heat exchange fluid, an outer surface and an inner surface wherein an inner surface of a heat conducting tube is provided with radially, inwardly extending, spaced apart members extending along said inner surface parallel to the longitudinal axis of said heat exchange tube thereby to present an increased surface area to a heat transfer fluid circulating through said tube.  
     
     
         2 . The heat exchange tube of  claim 1  wherein said inwardly extending members comprise a plurality of spaced apart ridges that run along the inner wall of the tube parallel to the axis of the tube.  
     
     
         3 . The heat exchange tube of  claim 1  wherein said inwardly extending members comprise a plurality of spaced apart fins that run along the inner wall of the tube parallel to the axis of the tube.  
     
     
         4 . The heat exchange tube of  claim 1  wherein an outer wall of said heat exchange tube is provided with a series of radially outwardly extending members for increasing the heat exchange surface of the outer wall of the tube.  
     
     
         5 . The heat exchange tube of  claim 2  wherein said ridges define free ends disposed in the bore of said heat exchange tube, said free ends being adapted to provide additional surface area within said heat exchange tube.  
     
     
         6 . The heat exchange tube of  claim 5  wherein said free end of a ridge defines a semi-cylindrical shape having an upper surface and a lower surface for exposure to the heat transfer fluid circulating through the heat exchange tube.  
     
     
         7 . The heat exchange tube of  claim 5  wherein said free end of a ridge defines a channel for exposure to the heat transfer fluid circulating through the heat exchange tube.  
     
     
         8 . The heat exchange tube of  claim 5  wherein said free end of a ridge is planer and defines an upper face and lower faces for exposure to the heat transfer fluid circulating through the heat exchange tube.  
     
     
         9 . A heat exchange tube defining a bore for the circulation of a heat exchange fluid, an outer surface and an inner surface wherein an inner surface of a heat conducting tube is provided with radially, inwardly extending, spaced apart members extending along said inner surface parallel to the longitudinal axis of said heat exchange tube and an outer wall of said heat exchange tube is provided with a series of radially outwardly extending members for increasing the heat exchange surface of the outer wall of the tube, said inwardly extending members having free ends disposed in the bore of said heat exchange tube, said inwardly extending members decreasing in cross section from said inner wall surface to said free end, said outwardly extending members having free ends disposed radially outwardly away from said outer surface of said heat exchange tube, said outwardly extending members decreasing in cross section from said free end to said outer surface of said heat exchange tube.  
     
     
         10 . A heat exchanger for the exchange of heat energy between a fluid of a higher temperature to a fluid of a lower temperature comprising at least two heat exchange tubes as defined in  claim 1  through which a heat exchange fluid is circulating, an outer surface of said heat exchange tubes being contacted by a second fluid having a different temperature than the heat exchange fluid.  
     
     
         11 . The heat exchanger of  claim 10  wherein the heat exchange fluid is water and and the second fluid is a mixture of a hot combustion gas and air.  
     
     
         12 . The heat exchanger of  claim 11  for the production of steam.