Multi-spiral upset heat exchanger tube

Abstract

A heat exchanger tube is provided that includes an inner diameter, an outer diameter and a longitudinal axis. The heat exchanger includes at least two spiral upsets protruding from the inner diameter of the tube and spiraling around the longitudinal axis of a length of the tube. The at least two spiral upsets include a first spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis, and a second spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis. In one embodiment, the angle of the first spiral upset with respect to the longitudinal axis is approximately equal to the angle of the second spiral upset with respect to the longitudinal axis, such that the first and second spiral upsets are approximately parallel. In another embodiment, the absolute value of the angle of the first spiral upset with respect to the longitudinal axis is different from the absolute value of the angle of the second spiral upset with respect to the longitudinal axis, such that the first and second spiral upsets intersect at least once. A method of manufacturing a heat exchanger tube is also provided.

1 . A heat exchanger tube comprising: 
 an inner diameter, an outer diameter and a longitudinal axis; and    at least two spiral upsets protruding from the inner diameter of the tube and spiraling around the longitudinal axis of a length of the tube, wherein the at least two spiral upsets comprise: 
 a first spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis, and  
 a second spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis, wherein the angle of the first spiral upset with respect to the longitudinal axis is approximately equal to the angle of the second spiral upset with respect to the longitudinal axis, such that the first and second spiral upsets arc approximately parallel.  
   
     
     
         2 . The heat exchanger tube  claim 1 , wherein the cross-sectional shape of the first spiral upset is approximately the same as the cross-sectional shape of the second spiral upset.  
     
     
         3 . The heat exchanger tube  claim 1 , wherein the cross-sectional shape of the first spiral upset is different from the cross sectional shape of the second spiral upset.  
     
     
         4 . The heat exchanger tube  claim 1 , wherein the cross-sectional shape of the first spiral upset is chosen from the group consisting of semi-circular, semi-rectangular, poly-sided, V-shaped and U-shaped and the cross-sectional shape of the second spiral upset is chosen from the group consisting of semi-circular, semi-rectangular, poly-sided, V-shaped and U-shaped.  
     
     
         5 . The heat exchanger tube  claim 1 , wherein the depth of protrusion of the first spiral upset from the inner diameter of the tube is approximately equal to the depth of protrusion of the second spiral upset from the inner diameter of the tube.  
     
     
         6 . The heat exchanger tube  claim 1 , wherein the depth of protrusion of the first spiral upset from the inner diameter of the tube is different from the depth of protrusion of the second spiral upset from the inner diameter of the tube.  
     
     
         7 . The heat exchanger tube  claim 1 , wherein the pitch of the first spiral upset is approximately equal to the pitch of tie second spiral upset.  
     
     
         8 . The heat exchanger tube  claim 1 , wherein the pitch of the first spiral upset is different from the pitch of the second spiral upset.  
     
     
         9 . The heat exchanger tube  claim 1 , wherein the cross-sectional shape of the first spiral upset is different from the cross-sectional shape of the second spiral upset, wherein the depth of protrusion of the first spiral upset from the inner diameter of the tube is different from the depth of protrusion of the second spiral upset from the inner diameter of the tube, and wherein the pitch of the first spiral upset is different from the pitch of the second spiral upset.  
     
     
         10 . A heat exchanger tube comprising: 
 an inner diameter, an outer diameter and a longitudinal axis; and    at least two spiral upsets protruding from the inner diameter of the tube and spiraling around the longitudinal axis of a length of the tube, wherein the at least two spiral upsets comprise: 
 a first spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis, and  
 a second spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis, wherein the absolute value of the angle of the first spiral upset with respect to the longitudinal axis is different from the absolute value of the angle of the second spiral upset with respect to the longitudinal axis, such that the first and second spiral upsets intersect at least once.  
   
     
     
         11 . The heat exchanger tube  claim 10 , wherein the angle of the first spiral upset with respect to the longitudinal axis is smaller than 90° and the angle of the second spiral upset with respect to the longitudinal axis is larger than 90°, such that the first and second spiral upsets spiral in opposite directions, that is, the first spiral upset spirals in a clockwise direction and the second spiral upset spirals in a counter-clockwise direction.  
     
     
         12 . The heat exchanger tube  claim 10 , wherein the cross-sectional shape of the first spiral upset is approximately the same as the cross-sectional shape of the second spiral upset.  
     
     
         13 . The heat exchanger tube  claim 10 , wherein the cross-sectional shape of the first spiral upset is different from the cross-sectional shape of the second spiral upset.  
     
     
         14 . The heat exchanger tube  claim 10 , wherein the cross-sectional shape of the first spiral upset is chosen from the group consisting of semi-circular, semi-rectangular, poly-sided, V-shaped and U-shaped and the cross-sectional shape of the second spiral upset is chosen from the group consisting of semi-circular, semi-rectangular, poly-sided, V-shaped and U-shaped.  
     
     
         15 . The heat exchanger tube  claim 10 , wherein the depth of protrusion of the first spiral upset from the inner diameter of the tube is approximately equal to the depth of protrusion of the second spiral upset from the inner diameter of the tube.  
     
     
         16 . The heat exchanger tube  claim 10 , wherein the depth of protrusion of the first spiral upset from the inner diameter of the tube is different from the depth of protrusion of the second spiral upset from the inner diameter of the tube.  
     
     
         17 . The heat exchanger tube  claim 10 , wherein the pitch of the first spiral upset is approximately equal to the pitch of the second spiral upset.  
     
     
         18 . The heat exchanger tube  claim 10 , wherein the pitch of the first spiral upset is different from the pitch of the second spiral upset.  
     
     
         19 . The heat exchanger tube  claim 10 , wherein the cross-sectional shape of the first spiral upset is different from the cross-sectional shape of the second spiral upset, wherein the depth of protrusion of the first spiral upset from the inner diameter of the tube is different from the depth of protrusion of the second spiral upset from the inner diameter of the tube, and wherein the pitch of the first spiral upset is different from the pitch of the second spiral upset.  
     
     
         20 . A method of manufacturing a heat exchanger tube comprising: 
 providing a tube having an inner diameter, an outer diameter and a longitudinal axis; and    providing at least two spiral upsets protruding from the inner diameter of the tube and spiraling around the longitudinal axis of a length of the tube, wherein providing the at least two spiral upsets comprises: 
 providing a first spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis, and  
 providing a second spiral upset having a cross-sectional shape, a depth of protrusion from the inner diameter, a pitch, and an angle with respect to the longitudinal axis, wherein the angle of the first spiral upset with respect to the longitudinal axis is different from the angle of the second spiral upset with respect to the longitudinal axis, such that the first and second spiral upsets intersect at least once [is approximately equal to the angle of the second spiral upset with respect to the longitudinal axis, such that the first and second spiral upsets are approximately parallel].