Heat exchanger with modified diffuser surface

Abstract

A diffuser comprising an inlet passage, an outwardly diverging sidewall, and an outlet. The inlet, outwardly diverging sidewall and outlet each have an inside surface that defines an interior through which a gas or fluid passes in a flow direction from the inlet to the outlet. Wherein at least a region of the inside surface includes a plurality of individual surface features that are configured to reduce or eliminate unwanted boundary layer separation of gas or fluid that passes thereover.

1 . A diffuser that is connected to a heat exchanger for receiving a gas or fluid and directing the same to the heat exchanger, the diffuser having a body that comprises: 
 a gas or fluid inlet passage at one end of the body and extending a distance therein;    an outwardly diverging wall section extending radially away from the inlet passage with axial distance from the inlet passage; and    an outlet extending axially away from the outwardly diverging wall section;    wherein the inlet passage, the outwardly diverging wall, and outlet each have an inside surface that defines an interior through which a gas or fluid passes in a flow direction from the inlet passage to the outlet, and wherein at least a section of the inside surface includes a plurality of individual surface features that are disposed therealong.    
   
   
       2 . The diffuser as recited in  claim 1  wherein the individual surface features are projections that each project outwardly a distance therefrom and that have a radiused cross sectional profile.  
   
   
       3 . The diffuser as recited in  claim 1  wherein the plurality of individual surface features are positioned along at least a region of the inside surface of the outwardly diverging wall section.  
   
   
       4 . The diffuser as recited in  claim 3  wherein the plurality of individual surface features occupy at least about 10 percent of the surface area of the outwardly diverging wall section.  
   
   
       5 . The diffuser as recited in  claim 1  wherein the plurality of individual surface features are arranged within a plurality of rows, and wherein each row comprises a plurality of the individual surface features.  
   
   
       6 . The diffuser as recited in  claim 5  wherein the surface features in at least one row are arranged so they are not axially aligned with the surface features in an adjacent row.  
   
   
       7 . The diffuser as recited in  claim 1  wherein the outwardly diverging wall section is conical, wherein the plurality of individual surface features are in the form of dimples positioned along an inside surface of the outwardly diverging wall section and projecting outwardly a distance therefrom, and wherein the dimples are provided in two or more rows that each extend around the outwardly diverging wall section.  
   
   
       8 . The diffuser as recited in  claim 1  wherein the outwardly diverging wall section is curvilinear, wherein the plurality of individual surface features are in the form of dimples positioned along an inside wall surface of the outwardly diverging wall section and projecting outwardly a distance therefrom, and wherein the dimples are provided in two or more rows that each extend around the outwardly diverging wall section.  
   
   
       9 . A heat exchanger comprising a plurality of gas or fluid passages disposed within a shell, the plurality of gas or fluid passages being defining a first gas or fluid flow passage through the heat exchanger, and the shell defining a second gas or fluid flow passage through the heat exchanger that is separate from the first gas or fluid flow passage, and further comprising a diffuser that is connected to the heat exchanger and in gas or fluid flow communication with the first gas or fluid flow passage, the diffuser comprising: 
 an inlet passage for receiving a gas or fluid stream and directing the same to the first gas or fluid flow passage;    an outwardly diverging wall section extending away from the inlet passage; and    an outlet that extends away from the outwardly diverging wall section and that is connected with the heat exchanger;    wherein the outwardly diverging wall section includes a plurality of projections disposed along an inside surface and that extend outwardly a distance therefrom, wherein the projections are provided in two or more rows, and wherein the projections in each row are separated from one another.    
   
   
       10 . The heat exchanger as recited in  claim 9  wherein the projections have a radiused cross sectional profile.  
   
   
       11 . The heat exchanger as recited in  claim 9  wherein the plurality of projections occupy at least about  10  percent of the surface area of the outwardly diverging wall section.  
   
   
       12 . The heat exchanger as recited in  claim 9  wherein the projections in at least one row are arranged so they are not axially aligned with the projections in an adjacent row.  
   
   
       13 . The heat exchanger as recited in  claim 9  wherein the outwardly diverging wall section is conical, and wherein the plurality of projections are dimples having a radiused sued cross sectional profile.  
   
   
       14 . The heat exchanger as recited in  claim 9  wherein the outwardly diverging wall section is curvilinear, and wherein the plurality of projections are dimples having a radiused cross sectional profile.  
   
   
       15 . A method of reducing boundary layer separation in a gas or fluid flowing through a heat exchanger comprising an inlet diffuser, the diffuser having an inlet passage, an outwardly diverging side wall extending from the inlet passage, and an outlet extending from the outwardly diverging side wall, the method comprising the steps of: 
 forming a plurality of individual surface features on at least a portion of an inside surface of the outwardly diverging side wall; and    flowing a gas or fluid through the inlet passage, over the surface features and through the outlet, whereby plurality of individual surface features interrupts the creation of eddy currents along the outwardly diverging side wall that reduces boundary layer separation the gas or fluid.    
   
   
       16 . The method as recited in  claim 15  wherein during the step of forming, the surface features are provided in the form of projections that each extend a distance from the inside surface, wherein the projections are provided in two or more rows, and wherein the projections within each row are separate from one another.  
   
   
       17 . The method as recited in  claim 15  wherein during the step of forming, the projections are provided in the form of dimples that each extend a distance from the inside surface and that have a radiused cross sectional profile.  
   
   
       19 . A method of making an inlet gas or fluid diffuser for use with a heat exchanger, the method comprising the steps of: 
 forming a diffuser body having a gas or fluid inlet passage at one end of the body and extending a distance therein, an outwardly diverging wall section extending radially away from the inlet passage with axial distance from the inlet passage, and an outlet extending axially away from the outwardly diverging wall section;    modifying a inside surface of at least a portion of the outwardly diverging wall section to include a plurality of individual surface features disposed therealong for reducing boundary layer separation of gas or fluid that is disposed thereover.