Fabrication of high surface area, high aspect ratio mini-channels and their application in liquid cooling systems

Abstract

The present invention provides methods and apparatuses which achieve high heat transfer in a fluid cooling system, and which do so with a small pressure drop across the system. The present invention teaches the use of wall features on the fins of a heat exchanger to cool fluid in a fluid cooling system. The present invention also discloses high aspect ratio, high surface area structures applicable in micro-heat exchangers for fluid cooling systems and cost effective methods for manufacturing the same.

1 . A stacked fin heat exchanger comprising:
 a. a cannister comprising:
 i. a bottom section; 
 ii. a lid; 
 iii. at least one wall; 
 iv. an inlet conduit for allowing fluid into the cannister; and 
 v. an outlet conduit for allowing fluid out of the cannister, wherein the bottom section, the lid and the at least one wall substantially, hermetically seal the cannister from fluid entering or exiting the cannister, except for the inlet conduit or the outlet conduit; and 
   b. a plurality of fins, each individual fin with at least one wall feature, wherein the plurality of fins are coupled to the bottom section of the cannister such that the individual fins are stacked substantially parallel to one another, forming channels having substantially vertical walls, wherein the wall features enhance the surface area of the channels, wherein the channels have a high surface area to volume aspect ratio, and wherein fluid input into the cannister through the inlet conduit flows through the channels and outputs the cannister through the outlet conduit.   
     
     
         2 . The stacked fin heat exchanger according to  claim 1 , wherein the plurality of fins are coupled to the bottom section through brazing. 
     
     
         3 . The stacked fin heat exchanger according to  claim 1 , wherein the plurality of fins are coupled to the bottom section through soldering or diffusion bonding. 
     
     
         4 . The stacked fin heat exchanger according to  claim 2 , wherein the plurality of fins are coupled to the bottom section through brazing. 
     
     
         5 . The stacked fin heat exchanger according to  claim 4 , further comprising:
 a. a brazing layer between the bottom section and the plurality of fins, wherein the brazing layer is configured to bond the plurality of fins to the bottom section when subjected to heat.   
     
     
         6 . The stacked fin heat exchanger according to  claim 5 , wherein the brazing layer is an alloy comprising a portion of copper and a portion of silver. 
     
     
         7 . The stacked fin heat exchanger according to  claim 5 , wherein the brazing layer is an alloy comprising a portion of copper, a portion of nickel, a portion of tin, and a portion of phosphorous. 
     
     
         8 . The stacked fin heat exchanger according to  claim 4 , further comprising:
 a. a brazing layer between the at least one wall and the lid, wherein the brazing layer is configured to bond the lid to the at least one wall when subjected to heat.   
     
     
         9 . The stacked fin heat exchanger according to  claim 8 , wherein the brazing layer is an alloy comprising a portion of copper and a portion of silver. 
     
     
         10 . The stacked fin heat exchanger according to  claim 8 , wherein the brazing layer is an alloy comprising a portion of copper, a portion of nickel, a portion of tin, and a portion of phosphorous. 
     
     
         11 . The stacked fin heat exchanger according to  claim 1 , wherein the bottom section is comprised of thermally conductive material. 
     
     
         12 . The stacked fin heat exchanger according to  claim 1 , wherein the bottom section is comprised of copper. 
     
     
         13 . The stacked fin heat exchanger according to  claim 1 , wherein the bottom section is comprised of aluminum. 
     
     
         14 . The stacked fin heat exchanger according to  claim 1 , wherein the plurality of fins are configured to be self-aligning, and wherein the plurality of fins are configured to be individually stacked within the cannister while remaining upright and substantially parallel to each other. 
     
     
         15 . The stacked fin heat exchanger according to  claim 14 , wherein the plurality of fins have an I-beam shape, wherein the individual fins comprise a beam section with flanges on a top and a bottom of the beam section, wherein the flanges extend substantially perpendicular to the beam section, wherein the flanges of adjacently stacked individual fins contact each other thereby causing the plurality of fins to self-align. 
     
     
         16 . The stacked fin heat exchanger according to  claim 14 , wherein the plurality of fins have a T-beam shape, wherein the individual fins comprise a beam section with flanges on a top of a beam section and a footer on each bottom corner of the beam section, wherein the flanges and footers extend substantially perpendicular to and equidistantly from the beam section, wherein the flanges of adjacently stacked individual fins contact each other and the footers of adjacently stacked individual fins contact each other, thereby causing the plurality of fins to self-align. 
     
     
         17 . The stacked fin heat exchanger according to  claim 14 , wherein each of the individual fins of the plurality of fins comprise a beam section with footers on each corner of the beam section, wherein the footers extend substantially perpendicular to and equidistantly from the beam section, wherein the footers of adjacently stacked individual fins contact each other, thereby causing the plurality of fins to self-align. 
     
     
         18 . The stacked fin heat exchanger according to  claim 1 , wherein the wall features are configured to affect the quality of fluid flow between the channels. 
     
     
         19 . The stacked fin heat exchanger according to  claim 1 , wherein the at least one wall feature extends the entire length of the individual fin. 
     
     
         20 . The stacked fin heat exchanger according to  claim 1 , wherein the at least one wall feature extends a partial length of the individual fin. 
     
     
         21 . The stacked fin heat exchanger according to  claim 1 , wherein the individual fins have wall features substantially equally spaced across the entire individual fin. 
     
     
         22 . The stacked fin heat exchanger according to  claim 1 , wherein the wall features have a diagonal configuration. 
     
     
         23 . The stacked fin heat exchanger according to  claim 1 , wherein the wall features have a sinusoidal configuration. 
     
     
         24 . The stacked fin heat exchanger according to  claim 1 , wherein the wall features have a zig-zag configuration. 
     
     
         25 . The stacked fin heat exchanger according to  claim 1 , wherein the wall features have a cross hatch pattern configuration. 
     
     
         26 . The stacked fin heat exchanger according to  claim 1 , wherein the wall features have a straight line configuration. 
     
     
         27 . The stacked fin heat exchanger according to  claim 1 , wherein at least one pair of adjacent individual fins from among the plurality of fins are complimentary fins, the complimentary fins comprising:
 a. a first fin with a first complimentary wall feature; and   b. a second fin with a second complimentary wall feature, wherein the complimentary fins are configured such that the first complimentary wall feature face the second complimentary wall feature when the plurality of fins are coupled to the bottom section of the cannister.   
     
     
         28 . The stacked fin heat exchanger according to  claim 27 , wherein at the first complimentary wall feature has a increasing gradient diagonal configuration and the second complimentary wall feature has a decreasing gradient diagonal configuration. 
     
     
         29 . The stacked fin heat exchanger according to  claim 1 , wherein the wall features are holes extending completely through the individual fins. 
     
     
         30 . The stacked fin heat exchanger according to  claim 1 , wherein the individual fins have more than one wall feature, and wherein at least one wall feature has a different shape than another wall feature. 
     
     
         31 . The stacked fin heat exchanger according to  claim 1 , wherein the individual fins have at least one wall feature comprising protrusions extending out of the individual fins. 
     
     
         32 . The stacked fin heat exchanger according to  claim 31 , wherein the protrusions are cylindrical pins. 
     
     
         33 . The stacked fin heat exchanger according to  claim 1 , wherein the individual fins have at least one wall feature comprising protrusions extending out of the individual fins and at least one wall feature comprising apertures cut into the individual fin. 
     
     
         34 . The stacked fin heat exchanger according to  claim 33 , wherein the apertures are holes extending completely through the individual fins and wherein the protrusions are cylindrical pins. 
     
     
         35 . The stacked fin heat exchanger according to  claim 1 , wherein a filler material is positioned within the channels formed by the plurality of fins. 
     
     
         36 . The stacked fin heat exchanger according to  claim 35 , wherein the filler material is a mesh material. 
     
     
         37 . The stacked fin heat exchanger according to  claim 36 , wherein the mesh material is comprised of a thermally conductive material. 
     
     
         38 . The stacked fin heat exchanger according to  claim 35 , wherein the filler material is a open-cell metal foam material. 
     
     
         39 . The stacked fin heat exchanger according to  claim 1 , wherein the cannister further comprises a manifold layer coupled to the top of the substantially vertical walls, wherein the manifold layer comprises a substantially hermetic cavity with at least one manifold aperture, wherein the inlet conduit is positioned on the manifold layer such that fluid enters the manifold layer via the inlet conduit and outputs from the manifold layer into the channels through the at least one manifold aperture. 
     
     
         40 . The stacked fin heat exchanger according to  claim 39 , wherein the manifold layer further comprises a fluid flow divider positioned in relation to the inlet conduit such that the fluid flow divider at least partially divides fluid entering the interface layer. 
     
     
         41 . A method of manufacturing a heat exchanger with a mini-channel fluid interface comprising the steps of:
 a. manufacturing an interface housing cannister having a bottom section, a lid, at least one wall section, an inlet conduit and an outlet conduit;   b. manufacturing a plurality of fins with wall features;   c. coupling the plurality of fins with the interface housing cannister, forming channels having substantially vertical walls, wherein the wall features enhance the surface area of the channels and wherein the plurality of fins are molecularly bonded to the bottom section; and   d. sealing the interface housing cannister with the lid.   
     
     
         42 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 41 , wherein the step of manufacturing a plurality of fins further comprises manufacturing individual fins with a wall feature comprising:
 a. cleaning a metal sheet to remove surface contaminants;   b. applying photoresist on both sides of the metal sheet;   c. exposing and developing the photoresist to form a patterned photoresist on the metal sheet;   d. exposing the photoresist patterned metal sheet to an etchant to remove material from an exposed portion of the metal sheet, thereby forming an etched metal sheet having a series of tabbed fins with pattern, each patterned fin having one or more tabs connected to an adjacent patterned fin on the etched metal sheet;   e. rinsing and drying the etched metal sheet; and   f. detaching individual patterned fins from the etched metal sheet by breaking the tabs.   
     
     
         43 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 41 , wherein the step of manufacturing individual fins further comprises etching at least one self-aligning feature on the individual fins, forming a plurality of self-aligning fins. 
     
     
         44 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 43 , further comprising the step of stacking the plurality of self-aligning fins along a width of the bottom surface of the interface housing cannister such that the self-aligning features cause the plurality of self-aligning fins to remain substantially parallel and upright. 
     
     
         45 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 41 , wherein the step of sealing the interface housing cannister further comprises:
 a. placing brazing material between the plurality of fins and the interface housing cannister, forming an assembled cannister bottom; and   b. heating the assembled cannister bottom with sufficient heat to thermally couple the plurality of fins and the interface housing.   
     
     
         46 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 41 , further comprising placing a brazing material on a top of the at least one wall of the interface housing cannister before sealing the interface housing cannister with the lid. 
     
     
         47 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 41 , further comprising:
 a. coupling a manifold layer to the heat exchanger between the interface layer and the lid, wherein the inlet conduit is located in the manifold layer, and wherein the manifold layer includes an aperture for allowing fluid to flow from the inlet conduit, through the manifold layer and into the interface layer.   
     
     
         48 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 41 , further comprising manufacturing a lid with an integrally formed manifold layer integrated within the lid. 
     
     
         49 . The method of manufacturing a heat exchanger with a mini-channel fluid interface according to  claim 41 , wherein the step of manufacturing a plurality of fins further comprises manufacturing individual fins with a wall feature using a mechanical method that includes cold rolling, laser cutting, stamping, or wet etching.