Heat Exchange Tube and Manufacturing Method Therefor

Abstract

A heat exchange tube is used to solve the problem of insufficient heat exchange efficiency of the conventional heat exchange tube. The heat exchange tube includes a tube, a first porous layer, and a second porous layer. The tube includes an inner wall. The first porous layer includes a plurality of holes. The first porous layer is disposed on the inner wall of the tube. The second porous layer includes a plurality of holes. The second porous layer is disposed on an inner surface of the first porous layer. An average diameter of the plurality of holes of the second porous layer is greater than an average diameter of the plurality of holes of the first porous layer. A method for manufacturing a heat exchange tube is also disclosed.

What is claimed is: 
     
         1 . A heat exchange tube comprising:
 a tube including an inner wall;   a first porous layer including a plurality of holes, wherein the first porous layer is disposed on the inner wall of the tube; and   a second porous layer including a plurality of holes, wherein the second porous layer is disposed on an inner surface of the first porous layer, and wherein an average diameter of the plurality of holes of the second porous layer is greater than an average diameter of the plurality of holes of the first porous layer.   
     
     
         2 . The heat exchange tube as claimed in  claim 1 , wherein an overall thickness of the first porous layer and the second porous layer is 0.125-0.3 times a wall thickness of the tube. 
     
     
         3 . The heat exchange tube as claimed in  claim 2 , wherein the wall thickness of the tube is 1-5 mm. 
     
     
         4 . The heat exchange tube as claimed in  claim 1 , wherein each of the tube, the first porous layer, and the second porous layer is made of a material selected from the group consisting of red copper, white copper, brass, and iron. 
     
     
         5 . The heat exchange tube as claimed in  claim 1 , wherein the material of each of the tube, the first porous layer, and the second porous layer includes at least 75 wt % of copper. 
     
     
         6 . The heat exchange tube as claimed in  claim 5 , wherein each of the tube, the first porous layer, and the second porous layer includes 75-95 wt % of copper and 5-25 wt % of nickel. 
     
     
         7 . A method for manufacturing a heat exchange tube, the method comprising:
 mixing first metal powders having a diameter of 10-45 μm with an adhesive to form a first paste;   sintering the first paste onto an inner wall of a tube at a sintering temperature of 575° C.-1035° C. to form a first porous layer on the inner wall of the tube;   mixing second metal powders having a diameter of 45-200 μm with the adhesive to form a second paste; and   sintering the second paste onto an inner surface of the first porous layer at a sintering temperature of 575° C.-1035° C. to form a second porous layer on the inner surface of the first porous layer, wherein an average diameter of the second metal powders is greater than an average diameter of the first metal powders.   
     
     
         8 . The method for manufacturing the heat exchange tube as claimed in  claim 7 , wherein an overall thickness of the first porous layer and the second porous layer is 0.125-0.3 times a wall thickness of the tube. 
     
     
         9 . The method for manufacturing the heat exchange tube as claimed in  claim 8 , wherein the wall thickness of the tube is 1-5 mm. 
     
     
         10 . The method for manufacturing the heat exchange tube as claimed in  claim 7 , wherein each of the tube, the first porous layer, and the second porous layer is made of a material selected from the group consisting of red copper, white copper, brass, and iron. 
     
     
         11 . The method for manufacturing the heat exchange tube as claimed in  claim 7 , wherein the material of each of the tube, the first porous layer, and the second porous layer includes at least 75 wt % of copper. 
     
     
         12 . The method for manufacturing the heat exchange tube as claimed in  claim 11 , wherein each of the tube, the first porous layer, and the second porous layer includes 75-95 wt % of copper and 5-25 wt % of nickel. 
     
     
         13 . The method for manufacturing the heat exchange tube as claimed in  claim 7 , wherein the adhesive is selected from the group consisting of polypropylene, polyethylene, polystyrene, polyethylene terephthalate, polymethacrylic acid, acetone, and xylene. 
     
     
         14 . The method for manufacturing the heat exchange tube as claimed in  claim 7 , further comprising before forming the first porous layer on the inner wall of the tube and/or forming the second porous layer on the inner surface of the first porous layer, mixing the first paste and/or the second paste with a pore-forming agent, wherein the pore-forming agent is selected from the group consisting of ferrous sulfate, ferric sulfate, mackinawite, marcasite, pyrite, troilite, pyrrhotite, greigite, amorphous iron sulfide, lead sulfide, coal, silicon dioxide, sodium silicate, sodium oxide, calcium oxide, magnesium oxide, potassium hydroxide, sodium hydroxide, ammonium nitrate, and potassium sulfate.