Heat exchanger with enhanced heat transfer

Abstract

A heat exchange device includes a plurality of flow passages. Each flow passage has an inlet and an outlet configured for hot fluid flow in a direction from the inlet to the outlet. Secondary heat transfer elements within and adjacent each flow passage have heat transfer characteristics varying in the direction of the hot fluid flow such that peak metal temperatures limit creep to acceptable values and such that transient thermal stresses are limited to values producing acceptable life of the device.

What is claimed is: 
     
         1 . A heat exchange device, comprising:
 a plurality of flow passages, each flow passage having an inlet and an outlet configured for hot fluid flow in a direction from the inlet to the outlet; and   secondary heat transfer elements within and adjacent each flow passage having heat transfer characteristics varying in the direction of the hot fluid flow such that peak metal temperatures, associated creep, and transient thermal stresses are limited to values producing acceptable life of the device.   
     
     
         2 . The heat exchange device of  claim 1 , wherein the heat transfer elements are positioned proximate the inlet and the outlet and gradually transition from straight heat transfer elements at the inlet to shaped heat transfer elements proximate the outlet. 
     
     
         3 . The heat exchange device of  claim 1 , wherein proximate the inlet of each flow passage includes a first predetermined number of straight heat transfer elements. 
     
     
         4 . The heat exchange device of  claim 3 , wherein an intermediate section between the inlet and outlet of the flow passage includes a second predetermined number of straight heat transfer elements and a third predetermined number of shaped heat transfer elements, wherein the second predetermined number is greater than the first predetermined number. 
     
     
         5 . The heat exchange device of  claim 4 , wherein proximate the outlet of the flow passage includes a fourth predetermined number of shaped heat transfer elements greater than the third predetermined number of shaped heat transfer elements. 
     
     
         6 . The heat exchange device of  claim 1 , wherein the shaped fins include wavy fins. 
     
     
         7 . The heat exchange device of  claim 1 , wherein the shaped fins allow for increased extended secondary heat transfer surface area. 
     
     
         8 . The heat exchange device of  claim 1 , further comprising:
 a first section and a second section, each of the first and second sections including the flow passages, wherein each flow passage includes heat transfer elements positioned therein to provide increased heat transfer in a direction from the inlet to the outlet.   
     
     
         9 . The heat exchange device of  claim 8 , wherein the first and second sections includes plate sections in a stacked arrangement with each of the flow passages having a bend at an outer edge of the heat exchange device configured to return high pressure fluid to a center manifold. 
     
     
         10 . The heat exchange device of  claim 9 , wherein the center manifold includes a first plenum at one side configured to allow fluid to enter the center manifold and a second plenum on the opposing side configured to allow fluid to exit the center manifold. 
     
     
         11 . The heat exchange device of  claim 10 , wherein fluid flows through the first plenum into an inlet of a respective flow passage within the first and second sections, enters the center manifold through an outlet of the respective flow passage, and exits the center manifold through the second plenum. 
     
     
         12 . A heat exchange device, comprising:
 a first section and a second section, each of the first and second sections including flow passages configured to cool fluid, each of the flow passages having an inlet and outlet wherein each flow passage includes heat transfer fins positioned proximate the inlet to the outlet, the fins transition from straight fins proximate the inlet to shaped fins proximate the outlet; and   a center manifold disposed between the first and second sections, wherein hot fluid enters the manifold at a first plenum, passes through the first and second sections and exits the center manifold at a second plenum.   
     
     
         13 . The heat exchange device of  claim 12 , wherein the shaped fins include wavy fins. 
     
     
         14 . The heat exchange device of  claim 12 , wherein the shaped fins include herringbone fins. 
     
     
         15 . The heat exchange device of  claim 12 , wherein the shaped fins allow for increased extended secondary heat transfer surface area.