Heat Exchangers with Turbulizers Having Convolutions of Varied Height

Abstract

A heat exchanger comprises at least one tube or plate pair defining a fluid flow passage which is reduced in height across a portion of its width. A turbulizer comprising a plurality of rows of convolutions is received inside the fluid flow passage in either the low pressure drop or high pressure drop orientation. The turbulizer includes convolutions of reduced height in order to at least partially fill the reduced-height portions of the fluid flow passage and thereby reduce bypass flow. In some preferred embodiments of the invention, heat exchanger tubes or plate pairs define fluid flow passages which are reduced in height along their edges, and the turbulizer is similarly reduced in height along its edges.

1 . A heat exchanger comprising:
 (a) at least one substantially flat heat exchange tube having top and bottom walls defining a hollow fluid flow passage, wherein the fluid flow passage has a height, a width and a length, with the height defined between said top and bottom walls of the tube, and with the tube extending lengthwise along a fluid flow axis, wherein the height of the fluid flow passage varies across the width so as to define a full-height area with a first height and a reduced-height area with a second height, wherein the first height is equal to a maximum height of the fluid flow passage and is greater than the second height, and wherein both the full-height area and the reduced-height area extend along the fluid flow axis;   (b) a turbulizer provided inside the fluid flow passage, wherein the turbulizer has a height, a width and a length, with the turbulizer extending lengthwise along the fluid flow axis and substantially completely filling the fluid flow passage, wherein the turbulizer comprises a plurality of rows of convolutions connected in side-by-side parallel relation to one another, and wherein the convolutions of each said row comprise a series of top surface portions and bottom surface portions interconnected by side portions;
 wherein the convolutions are pre-formed in a manufacturing process, prior to being provided inside the fluid flow passage, so as to define a plurality of full-height convolutions having a height substantially the same as the first height of the fluid flow passage, and a plurality of reduced-height convolutions having a maximum height substantially the same as the second height of the fluid flow passage, wherein the side portions of the reduced-height convolutions are shorter than the side portions of the full-height convolutions; and 
 wherein the full-height convolutions and the reduced height convolutions are arranged such that one of said full-height convolutions is adjacent to one of said reduced-height convolutions across the width of the turbulizer, and wherein said plurality of full-height convolutions and said plurality of reduced-height convolutions each extend lengthwise along the length of the turbulizer; and such that when the turbulizer is provided in the fluid flow passage, the full-height convolutions are positioned in the full-height area of the tube with their top surface portions in contact with the top wall of the tube and with their bottom surface portions in contact with the bottom wall of the tube, and the reduced-height convolutions are positioned in the reduced-height area of the tube. 
   
   
   
       2 . The heat exchanger of  claim 1 , wherein the top surface portions of said reduced-height convolutions are in contact with the top wall of the tube in said reduced-height area of the fluid flow passage, and/or the bottom surface portions of said reduced-height convolutions are in contact with the bottom wall of the tube in said reduced-height area of the fluid flow passage. 
   
   
       3 . The heat exchanger of  claim 1 , wherein said full-height area of the fluid flow passage is located centrally in the flow passage and said reduced-height area of said fluid flow passage is located at an edge of the flow passage, adjacent to said full-height area; and
 wherein the plurality of reduced-height convolutions of the turbulizer extend axially along an edge of the turbulizer, and wherein the plurality of reduced-height convolutions is adjacent to said plurality of full-height convolutions.   
   
   
       4 . The heat exchanger of  claim 1 , wherein the heat exchange tube comprises a pair of plates which are joined together at their edges and have spaced-apart central portions, wherein said top wall of the tube is provided by one of said plates and the bottom wall of the tube is provided by the other of said plates, and wherein the fluid flow passage is located between the central portions of the plates. 
   
   
       5 . The heat exchanger of  claim 1 , wherein the reduced-height area is located between opposite edges of the flow passage, and spaced therefrom, and said full-height area is located adjacent to said reduced-height area; and
 wherein the plurality of reduced-height convolutions is spaced from opposite axial edges of the turbulizer, and the plurality of full-height convolutions is adjacent to the plurality of reduced-height convolutions.   
   
   
       6 . The heat exchanger of  claim 1 , wherein the reduced-height convolutions have a reduced pitch relative to the full-height convolutions, such that the top surface portions of the reduced-height convolutions are narrower than the top surface portions of the full-height convolutions, and/or the bottom surface portions of the reduced-height convolutions are narrower than the bottom surface portions of the full-height convolutions. 
   
   
       7 . The heat exchanger of  claim 1 , wherein the top surface portions of the convolutions in each said row are substantially aligned with the bottom surface portions of the convolutions in an adjacent one of said rows. 
   
   
       8 . The heat exchanger of  claim 1 , wherein the rows of the turbulizer extend across the width of the turbulizer and transverse to the fluid flow axis, such that the convolutions define openings facing in a direction which is parallel to the fluid flow axis. 
   
   
       9 . The heat exchanger of  claim 8 , said full-height convolution and said reduced-height convolution which are located adjacent to one another across the width of the turbulizer are connected together by a top surface portion or a bottom surface portion of said full-height convolution. 
   
   
       10 . The heat exchanger of  claim 8 , wherein each of the rows of the turbulizer includes at least one of said full-height convolutions and at least one of said reduced-height convolutions. 
   
   
       11 . The heat exchanger of  claim 8 , wherein the turbulizer comprises an offset strip fin. 
   
   
       12 . The heat exchanger of  claim 8 , wherein the top surface portions and the bottom surface portions of both the full-height convolutions and the reduced-height convolutions are flat and substantially parallel to the top and bottom walls of the tube. 
   
   
       13 . The heat exchanger of  claim 1 , wherein the rows of the turbulizer extend along the length of the turbulizer and parallel to the fluid flow axis, such that the convolutions define openings facing in a direction which is transverse to the fluid flow axis. 
   
   
       14 . The heat exchanger of  claim 13 , wherein said turbulizer comprises at least one of said rows in which all of the convolutions are said reduced-height convolutions, and at least one of said rows in which all of the convolutions are said full-height convolutions. 
   
   
       15 . The heat exchanger of  claim 14 , wherein said at least one row of reduced-height convolutions is adjacent to said at least one row of full-height convolutions. 
   
   
       16 . The heat exchanger of  claim 13 , wherein the top surface portions and the bottom surface portions of the reduced-height convolutions are flat and substantially parallel to the top and bottom walls of the tube. 
   
   
       17 . The heat exchanger of  claim 16 , wherein the top surface portions and the bottom surface portions of the full-height convolutions are rounded. 
   
   
       18 . The heat exchanger of  claim 13 , wherein the turbulizer comprises an offset strip fin. 
   
   
       19 . The heat exchanger of  claim 18 , wherein the side portions of the convolutions are interrupted approximately at their midpoints by shoulders through which adjacent rows of said turbulizer are connected together.