Heat transfer enhancement for a condensing furnace

Abstract

A heat exchanger is provided including a plurality of heat exchanger tubes. A first fluid flows through each heat exchanger tube and a second fluid flows around an exterior of each heat exchanger tube. A turbulator is disposed within at least one of the heat exchanger tubes. The turbulator extends at least a portion of the length of the heat exchanger tube. The turbulator includes a generally flat sheet of material having a plurality of integrally formed turbulence generating elements. The turbulence generating elements extend from a plane of the sheet of material into the first fluid flow. A disturbance is created in the first fluid flow adjacent each turbulence generating element.

1 . A heat exchanger comprising:
 a plurality of heat exchanger tubes, wherein a first fluid flows through each heat exchanger tube and a second fluid flows around an exterior of each heat exchanger tube; and   a turbulator disposed in one of the heat exchanger tubes and extending at least a portion of a length of the heat exchanger tube, the turbulator including a generally flat rectangular sheet having a plurality of integrally formed turbulence generating elements extending from a plane of the rectangular sheet into the first fluid flow, wherein a disturbance is generated in the first fluid flow adjacent each turbulence generating element.   
     
     
         2 . The heat exchanger according to  claim 1 , wherein the plurality of turbulence generating elements are uniform in size and shape. 
     
     
         3 . The heat exchanger according to  claim 1 , wherein the plurality of turbulence generating elements are triangular in shape. 
     
     
         4 . The heat exchanger according to  claim 1 , wherein the plurality of turbulence generating elements are one of rectangular, oval, racetrack and semi-circular in shape. 
     
     
         5 . The heat exchanger according to  claim 1 , wherein the plurality of turbulence generating elements are aligned about a longitudinal axis of the rectangular sheet. 
     
     
         6 . The heat exchanger according to  claim 1 , wherein at least one of the turbulence generating elements extends from the plane of the rectangular sheet in a first direction, and at least one of the turbulence generating elements extends from the plane of the rectangular sheet in a second, substantially opposite direction. 
     
     
         7 . The heat exchanger according to  claim 1 , wherein a width W of at least a portion of a turbulence generating element is in the range of about 4 mm to about 25 mm. 
     
     
         8 . The heat exchanger according to  claim 7 , wherein each of the plurality of turbulence generating elements has a length L and chord ratio (L/W) in the range of about 1 to about 5. 
     
     
         9 . The heat exchanger according to  claim 7 , wherein a pitch P extends between adjacent turbulence generating elements extending from the plane of the rectangular sheet in the first direction, and a same side pitch ratio (P/W) is in the range of about 5 to about 100. 
     
     
         10 . The heat exchanger according to  claim 7 , wherein a distance X is defined between a first turbulence generating element extending from the plane of the rectangular sheet in a first direction and a second turbulence generating element extending from the plane of the rectangular sheet in a substantially opposite direction, and an opposite side pitch ratio (X/W) is in the range of about 0 to about 50. 
     
     
         11 . The heat exchanger according to  claim 1 , wherein an approach angle is formed between the chord line of the turbulence generating element and an airstream velocity vector and the airstream velocity vector, the approach angle being in the range of about 10 degrees to 90 degrees. 
     
     
         12 . The heat exchanger according to  claim 1 , wherein at least one of the plurality of turbulence generating elements has an inclination angle other than 90 degrees. 
     
     
         13 . The heat exchanger according to  claim 1 , wherein a first end of the turbulator includes at least one securing element that supports the turbulator within the heat exchanger tube. 
     
     
         14 . The heat exchanger according to  claim 1 , wherein a first end of the turbulator is rotated relative to a second end of the turbulator about a central longitudinal axis such that the turbulator includes at least one twist. 
     
     
         15 . A condensing furnace comprising:
 a heat exchanger having an inlet and an outlet, wherein a first fluid flows through the heat exchanger and a second fluid flows around an exterior of the heat exchanger; and   a turbulator positioned within the heat exchanger, the turbulator extending at least a portion of a length of the heat exchanger, the turbulator including:
 a generally flat rectangular sheet; and 
 a plurality of turbulence generating elements formed integrally with the rectangular sheet and extending from a plane of the rectangular sheet into the first fluid flow, such that a disturbance is created in the first fluid flow adjacent each turbulence generating element. 
   
     
     
         16 . A heat exchanger comprising:
 a plurality of heat exchanger tubes, wherein a first fluid flows through each heat exchanger tube and a second fluid flows around an exterior of each heat exchanger tube; and   a turbulator disposed in one of the heat exchanger tubes and extending at least a portion of a length of the heat exchanger tube, the turbulator including a generally flat sheet of material having a substantially non-linear contour configured to interrupt a flow of the first fluid through the heat exchanger tube.   
     
     
         17 . The heat exchanger according to  claim 16 , wherein the turbulator is bent about a longitudinal axis thereof. 
     
     
         18 . The heat exchanger according to  claim 16 , wherein the sheet of material has a general zig-zag shape and includes a plurality of opposing turns. 
     
     
         19 . The heat exchanger according to  claim 18 , wherein the generally zig-zag shape is formed from a plurality of staggered generally linear sections connected by a plurality of angled sections, each successive angled section being oriented in a first direction opposite a second direction of a preceding angled section. 
     
     
         20 . The heat exchanger according to  claim 18 , wherein the turbulator includes a plurality of turbulence generating elements extending from a plane of the flat sheet of material into the first fluid flow, each of the plurality of turbulence generating elements being configured to create a disturbance in the first fluid. 
     
     
         21 . The heat exchanger according to  claim 20 , wherein the plurality of turbulence generating elements are formed in the opposing turns of the flat sheet. 
     
     
         22 . The heat exchanger according to  claim 21 , wherein the plurality of turbulence generating elements are triangular in shape. 
     
     
         23 . The heat exchanger according to  claim 21 , wherein at least one of the turbulence generating elements extends from the plane of the sheet of material in a first direction, and at least one of the turbulence generating elements extends from the plane of the sheet of material in a second, substantially opposite direction. 
     
     
         24 . The heat exchanger according to  claim 21 , wherein a width W of at least a portion of a turbulence generating element is in the range of about 4 mm to about 25 mm. 
     
     
         25 . The heat exchanger according to  claim 24 , wherein the plurality of turbulence generating elements have a chord ratio (L/W) in the range of about 1 to about 5. 
     
     
         26 . The heat exchanger according to  claim 24 , wherein a pitch P extends between adjacent turbulence generating elements extending from the plane of the sheet of material in the first direction, and a same side pitch ratio (P/W) is in the range of about 2 to about 100. 
     
     
         27 . The heat exchanger according to  claim 24 , wherein a distance X is defined between a first turbulence generating element extending from the plane of the rectangular sheet in a first direction and from a second turbulence generating element extending from the plane of the rectangular sheet in a substantially opposite direction, and an opposite side pitch ratio (X/W) is in the range of about 0 to about 50. 
     
     
         28 . The heat exchanger according to  claim 20 , wherein an approach angle is formed between the chord line of the turbulence generating element and an airstream velocity vector and the airstream velocity vector, the approach angle being in the range of about 10 degrees to 90 degrees. 
     
     
         29 . The heat exchanger according to  claim 20 , wherein at least one of the plurality of turbulence generating elements has an inclination angle other than 90 degrees. 
     
     
         30 . The heat exchanger according to  claim 16 , wherein a first end of the turbulator includes at least one securing element configured to support the turbulator within the heat exchanger tube. 
     
     
         31 . A condensing furnace comprising:
 a heat exchanger having an inlet and an outlet, wherein a first fluid flows through the heat exchanger and a second fluid flows around an exterior of the heat exchanger; and   a turbulator positioned within the heat exchanger, the turbulator extending at least a portion of a length of the heat exchanger, the turbulator including a generally flat sheet of material having a substantially non-linear contour configured to interrupt a flow of the first fluid through the heat exchanger tube.