Enhanced condensation heat-transfer tube

Abstract

This invention provides an enhanced condensation heat-transfer tube, which is furnished with spiral fins on the outer surface. Axial spacing between the said fins regularly changes in width. In a preferred embodiment, the said fins regularly change in height along the axle. Such spiral fins with even changes in height and spacing change the surface tension of the condensate membrane between the fins outside of the tube, so as to enhance the “Gregorig” effect (average heat resistance reduces due to uneven thickness of condensate membranes). In this way, it further strengthens condensation heat transfer effects outside of the tube. At the same time, it accelerates flowing of the condensate to the bottom, enhances heat transfer effect, and improves the tube bundle effect.

1 . An heat-transfer tube for enhanced condensation, comprising a tube Body, and outer spiral fins integrated on outer surface of the tube body wherein the spiral fins are featured by regular changes in axial direction and in the width of spacing between the said fins. 
     
     
         2 . The heat-transfer tube according to  claim 1 , wherein said spiral fins having smooth surface; or said spiral fins being slotted fins by grooving the smooth fin on the top or on both rides. 
     
     
         3 . The heat-transfer tube according to Claim  1 , wherein  26  to  60  of said spiral tins are provided in every inch along the axial direction of the outer surface of the tube body and the spiral fins are axially spaced 0.4 to 1 mm. 
     
     
         4 . The heat-transfer tube according to  claim 1 , wherein the spacing between fins regularly changes in the axial direction with alternating wide and narrow spacing; or the spacing between fins regularly changes in the axial direction with alternating wide spacing and two narrow spacings; or the spacing between fins regularly changes in the axiai direction with alternating two wide spacings and one narrow spacing. 
     
     
         5 . The heat-transfer tube ncording to  claim 1 , wherein said spiral fins have regular changes in the height of the said spiral fins in the axial direction. 
     
     
         6 . The heat-transfer tube according to  claim 5 , wherein said spiral fins are 0.1 to 0.4 mm thick, with their height ranging between 0.4 to 1.5 mm. 
     
     
         7 . The heat-transfer tube according to  claim 5 , is featured by the following:
 the height of the said spiral fins regularly changes along the axial direction with alternating one high fin and one short fin; or   the height of the said spiral fins regularly changes along the axial direction with alternating one high fin and two short fins; or   the height of the said spiral fins regularly changes along the axial direction with alternating two high fins and one short fin.   
     
     
         8 . The heat-transfer tube according to  claim 1 , is featured by that the helical angle of the said spiral fins ranges from 0.3° to 1.5°. 
     
     
         9 . The heat-transfer tube according to  claim 1 , wherein threaded ridges are furnished on the inner surface of the said heat-transfer tube. 
     
     
         10 . The heat-transfer tube according to  claim 9 , wherein the said threaded ridges are angled between the threaded ridge and the axle ranging from 30° to 60°; said threaded ridge has 6 to 60 internal threads, with their height ranging from 0.1 o 0.6 mm. 
     
     
         11 . The heat-transter tube according to  claim 5 , wherein threaded ridges are furnished on the inner surface of the said heat-transfer tube. 
     
     
         12 . The heat-transfer tube according to  claim 11 , wherein the said threaded ridges are angled between the threaded ridge and the axle ranging from 30° to 60°; said threaded ridge has 6 to 60 internal threads, with their height ranging from 0.1 to 0.6 mm.