Heat Transfer Device And Method

Abstract

methods of making such devices are disclosed. One such device is a fin having a primary texture and a secondary texture, wherein each texture has an average amplitude. The amplitude is an elevation change from a peak of the texture to an adjacent valley. The average amplitude of the secondary texture is between 1% and 90% of the average amplitude of the primary texture. Such a fin may have holes, some of which may be used to accommodate tubes passing through the fin.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001]This application claims the benefit of priority to U.S. provisional patent application Ser. No. 61/166,473, which was filed on Apr. 3, 2009.

FIELD OF THE INVENTION

[0002]The present invention relates to devices for transferring heat from one substance to another, and methods of making such devices.

BACKGROUND OF THE INVENTION

[0003]In the prior art, there are heat transfer devices that have fins with holes to accommodate tubes. The tubes are designed to carry a fluid that is sought to be heated or cooled by the transfer of heat to or from another fluid, which surrounds the tube and fins. The prior art describes fins that are non-planar, and the prior art also describes fins that have open holes that allow for the passage of fluid from one side of the fin to the other side.

[0004]However, we have discovered a particular type of heat transfer device in the form of a fin which is not described in the prior art, and which achieves significant improvement in transferring heat.

SUMMARY OF THE INVENTION

[0005]The invention may be embodied as a heat transfer device in the form of a fin, which may be used with one or more tubes and one or more collars. The tube may be made of a thermally-conductive material, and may be sized and shaped to carry a "fluid", which may be a liquid, a gas, a two-phase mixture (e.g. refrigerants); a Newtonian or non-Newtonian; a single phase fluid or a two phase fluid; slurry (e.g. a food product or tar). The thermally-conductive material of the tube may conduct heat away from the fluid in the tube, or may conduct heat to the fluid in the tube.

[0006]The fin may be made of a thermally-conductive material. The fin has an outer perimeter and two major surfaces, which are spaced apart by the thickness of the fin. A perimeter edge provides a transition from a first of the major surfaces to a second of the major surfaces. The thickness-distance may be substantially constant. Holes may extend through the fin from one major surface to the other major surface. The tubes may be positioned to extend through some of the holes, but not all of the holes. Those holes that do not have tubes remain open to allow fluid that is on one side of the fin, for example fluid that has contacted the first major surface, to pass through the hole to the other side of the fin, where the second major surface is.

[0007]Each major surface of the fin has peaks and valleys, which may be formed on the fin by a rolling, stamping, embossing or cold working operation. In addition, the peaks and valleys may be provided by applying a material that has the peaks and valleys to a base material. Peaks on the first major surface correspond to valleys on the second the major surface, and in this manner, the thickness-distance of the fin remains substantially constant.

[0008]A collar may be provided in the area where a tube passes through a fin. The collar may be in contact with the fin and the tube in order to provide a conductive pathway for transferring heat by conduction. Via the collar, heat may be transferred from the tube to the fin, or from the fin to the tube, depending on the relative temperatures of the fluid in the tube and the fluid outside the tube.

[0009]In a particular embodiment of the invention, a heat transfer device has a fin having a primary texture and a secondary texture, wherein each texture has an average amplitude, the amplitude being an elevation change from a peak of the texture to an adjacent valley, and the average amplitude of the secondary texture is between 1% and 90% of the average amplitude of the primary texture.

[0010]The invention may be embodied as a method of making a heat transfer device. In one such method, a substantially flat thermally-conductive fin material may be provided. The fin material may have a first major surface and a second major surface, wherein the major surfaces are spaced apart by a thickness-distance which is substantially constant. The fin material may be rolled, stamped, embossed or cold-worked to change the thermally-conductive material from flat to non-flat, but once changed, the thickness-distance of the non-flat material is substantially constant.

[0011]Holes may be formed in the fin material to extend from the first major surface to the second major surface by punching, drilling, piercing or some other process. The holes may be formed either before or after the fin material is changed from substantially flat to substantially non-flat.

[0012]A collar may be placed or formed on the fin material to coincide with some of the holes, and a tube may be placed in the collar. The collar may be secured to the tube and/or the fin in order to provide a conductive pathway for transferring heat by conduction. Some of the holes in the fin material remain open to allow fluid to pass from one side of the fin to the other side of the fin, thereby permitting fluid that has contacted the first major surface to pass through the hole to the second major surface.

[0013]In a particular method according to the invention, a substantially flat thermally-conductive fin material is provided and formed by rolling, stamping, embossing or cold working to impart a primary texture. A secondary texture is also imparted to the fin material, either before or after imparting the primary texture. Each texture is imparted to have its own average amplitude, the amplitude being an elevation change from a peak of the texture to an adjacent valley, and the average amplitude of the secondary texture is between 1% and 90% of the average amplitude of the primary texture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]For a fuller understanding of the nature and objects of the invention, reference should be made to the accompanying drawings and the subsequent description. Briefly, the drawings are:

[0015]FIG. 1 depicts a heat transfer device according to the invention along with tubes and collars.

[0016]FIG. 2 depicts a fin that could be used in a heat transfer device according to the invention.

[0017]FIG. 3 depicts another fin according to the invention, and this fin has a coated surface with the primary and secondary textures thereon.

[0018]FIG. 4 is flow diagram showing a method according to the invention;

[0019]FIG. 5 depicts another fin according to the invention, and this fin has a primary texture and a secondary texture; and

[0020]FIG. 6 is flow diagram showing another method according to the invention.

FURTHER DESCRIPTION OF THE INVENTION

[0021]FIG. 1 depicts a heat exchanger 10 according to the invention. The heat exchanger 10 shown in FIG. 1 has a tube 13 extending through a hole 16 in a fin 19, and a collar 22 attached to the tube 13 and the fin 19. One of the fins 19 of FIG. 1 is shown in FIG. 2. The tube 13 is made of a thermally-conductive material, such as copper, copper alloy, steel, stainless steel alloy, copper-nickel, titanium, stainless steel, duplex, nickel, carbon or aluminum, and is sized and shaped to carry a fluid, which may be a liquid, a gas or other type of fluid, including mixed phase fluids. The thermally-conductive material of the tube 13 may conduct heat either away from the fluid in the tube 13, or to the fluid in the tube 13, depending on the temperature of the fluid in the tube 13 relative to the temperature of fluid surrounding the tube 13.

[0022]The fin 19 shown in FIG. 1 is made of a thermally-conductive material, such as those identified above. The material of the fin 19 may be the same material as the tube 13, or a different material. The fin material may be heat treated or work hardened to impart desired characteristics to the fin 19. Also, the fin 19 may be a composite of two or more materials. FIG. 3 shows a composite fin having a substrate 20 and a coating 21.

[0023]The fin 19 has two major surfaces 25, 28 and a perimeter edge 31 extending between the major surfaces 25, 28. The perimeter edge 31 has a thickness distance 48 that is substantially constant, and thus the first major surface 25 is spaced apart from the second major surface 28 in a substantially consistent manner. As such, the fin 19 is less likely to have stress locations and fewer weaknesses that could reduce the useful life of the fin 19. The major surfaces 25, 28 of the fin 19 each have peaks 33 and valleys 36. See FIG. 2. It should be noted that peaks 33 on the first major surface 25 correspond to valleys 36 on the second the major surface 28. In this manner, the thickness-distance 39 of the fin 19 remains substantially constant. Such a fin 19 may be formed by rolling, stamping, embossing or cold working a piece of thermally conductive material to have the peaks 33 and valleys 36. In addition, the peaks 33 and valleys 36 may be formed by placing a coating material onto a base material of the fin, and joining the coating material to the base material of the fin, wherein the coating material has the peaks and valleys formed in it. FIG. 3 depicts such a fin.

[0024]Holes 16 extend through the fin 19 from one major surface to the other major surface. The arrangement in FIG. 1 has tubes 13, which extend through some of the holes 16A, but not all of the holes 16. Those holes that do not have tubes 13 remain open to allow fluid that is on one side of the fin 19 to pass through the open holes 16A to the other side of the fin 19. The open holes 16A have several advantages. First, pressure differences from one side of a fin 19 to another side of a fin 19 may be reduced. Second, fluid flowing from one side of a fin 19 to the other side of a fin 19 will cause turbulence, which improves the ability of the fin 19 to transfer heat to or from the fluid that surrounds the tube 13. Third, the surface which bounds the open hole 16A provides additional surface area through which heat may be transferred. Also, the open holes 16A allow the flow to be directed to various locations in the heat exchanger by changing the size and/or location of the hole. It should be noted that the open holes 16A may be provided in a repeating pattern, but ay also be provided in a non-repeating pattern.

[0025]A collar 22 may be provided in the area where a tube 13 passes through a fin 19. The collar 22 may be in contact with the fin 19 and tube 13 in order to provide a conductive pathway for transferring heat by conduction. Via the collar 22, heat may be transferred from the tube 13 to the fin 19, or from the fin 19 to the tube 13, depending on the relative temperatures of the fluid in the tube 13 and the fluid outside the tube 13.

[0026]Holes 16 in the fin material extend from the first major surface to the second major surface and may be formed by punching, drilling, piercing or some other process. The holes 16 may be formed either before after the fin material is changed from substantially flat to substantially non-flat. The holes 16 may be shaped to be square, round, oval, rectangular, parallelogram, or triangular, but the invention is not limited to these or other standard geometric shapes. The shape of the holes 16 need not be consistent, and instead may be a mixture of shapes for any particular fin 19. See FIG. 2. Also, the shapes of holes 16 in one fin 19 may be different from the shape of holes 16 in another fin 19. In one embodiment of the invention, the material that is removed to form the hole 16 is not left attached to the fin material, and is instead entirely removed from the fin material. In this manner, fluid passing through the open hole 16A is not preferentially directed in any particular direction, and is free to pass parallel to the tube 13.

[0027]The open holes 16A in the fin material allow fluid to pass from one major surface of the fin 19 to the other major surface of the fin 19, thereby permitting fluid that has contacted the first major surface 25 to pass through the open hole 16A to the second major surface 28. Furthermore, the size of the open holes 16A may be selected to provide a desired flow velocity. A small open hole 16A will provide higher velocity and therefore more turbulence (and a corresponding higher rate of heat transfer), while a larger open hole 16A will provide lower velocity and therefore less turbulence. The diameter of the open holes 16A may be quite small, for example as small as one-tenth the thickness-distance 39, but the invention is not limited to this size. Although the thickness-distance 39 may be 0.005 inches to 0.125 inches, the present invention allows for holes 16 to be made in the fin material by piercing when the fin material is in the range of 0.014 to 0.125 inches, which may afford economic and performance advantages.

[0028]A collar 22 may be placed or formed on the fin material to coincide with some of the holes 16, and a tube 13 may be placed in the collar 22. The collar 22 may be secured to the tube 13 and/or the fin 19 in order to provide a conductive pathway for transferring heat by conduction. The collar 22 may be attached to the fin 19 or the tube 13 by press fitting, friction fitting, expanding the tube 13, welding, brazing, soldering, or through the use of an adhesive.

[0029]The peaks 33 and valleys 36 may be sized so that the elevation change from a peak 33 on the first major surface 25 to an adjacent valley 36 on the first major surface 25 is less than the thickness-distance 39. Such an arrangement allows for low pressure drop, while imparting turbulence to fluid moving across the fin 19. Alternatively, the peaks 33 and valleys 36 may be sized so that the elevation change from a peak 33 on the first major surface 25 to an adjacent valley 36 on the first major surface 25 is more than the thickness-distance 39. Such an arrangement may provide additional turbulence and a higher pressure drop for a similar amount of fluid moving across the fin 19.

[0030]One or both of the major surfaces 25, 28 may have a surface finish that is designed to improve heat transfer. Such a surface finish may be achieved by electro-polishing, pickling, passivation, anodizing, sand blasting, chemical treatment, sputtering, spraying, ion deposition, vacuum forming, and/or cleaning a major surface 25, 28.

[0031]The fin 19 may include flow disrupters 42 on one or both of the major surfaces 25, 28. The flow disrupters 42 may be raised or lowered areas on a major surface 25, 28 which present a change in elevation that is less than the elevation change provided by the peaks 33 and valleys 36. In this manner, the fin 19 may be thought of as having a primary texture corresponding to the peaks 33 and valleys 36, and a secondary texture corresponding to the flow disrupters 42. The purpose of the flow disrupters 42 is to disrupt flow and create turbulence the fluid flow that is highly proximate to a major surface 25, 28, and in particular to disrupt flow in the boundary layer. In this manner, additional heat transfer is achieved by causing fluid in the boundary layer to be non-uniform. As such, the peaks 33 and valleys 36 impart a macro-turbulence to fluid flow and the boundary layer near the fin 19, while the flow disrupters impart a micro-turbulence to the fluid flow that is very near the fin 19. Together, the macro-turbulence and the micro-turbulence caused by the non-flat surface of the fin 19 improve heat transfer significantly.

[0032]The flow disrupters 42 may be created by adding material to the thermally-conductive fin material to create a bump that is small relative to the peaks 33 and valleys 36. Also, the flow disrupters 42 may be created by moving portions of the fin material to create a divot, for example by a rolling operation. In one embodiment of the invention, the flow disrupters 42 are created prior to creating the peaks 33 and valleys 36. In one particular embodiment of the invention, the flow disrupters 42 extend from or into the major surface by less than the thickness-distance 39 of the fin material. The flow disrupters 42 may be arranged in a repeating or a non-repeating pattern. FIG. 2 shows a non-repeating pattern. The flow disrupters 42 may be provided as part of a coating 45 disposed on at least one of the major surfaces 25, 28. See FIG. 3. The coating 45 may be adhered to a substrate 20 of the fin 19.

[0033]The flow disrupters 42 may be sized so that they do not extend from a major surface 25, 28 by more than 90% of the elevation change from a peak 33 to an adjacent valley 36 (sometimes herein referred to as the "peak-to-valley elevation distance 48"). The flow disrupters 42 may be sized so that they extend at least 1% of the peak-to-valley elevation distance 48.

[0034]The fin 19 may include a coating that has been applied to at least one of the major surfaces in order to impart beneficial properties to the fin. For example, the coating may be made of a material that has the ability to absorb more radiant heat than it emits. Such materials include galvanically applied black chrome, black nickel, aluminum oxide with nickel, and titanium-nitride-oxide. Other coatings may be chemically reactive (such as titanium, zirconium, chromium aluminum and some polymers), catalytic (such as platinum, paladium and rhodium), corrosion-resistant (such as teflon and xylan), fouling resistant (such as Teflon, epoxy based polymer, heresite, and ecoatings), and/or anti-bacterial-resistant (such as silver-ion, teflon, xylan and zinc/titanium-dioxide). Such a coating may be applied to the fin electrically, by sputtering, spraying, vacuum forming, or by a rolling operation.

[0035]In an embodiment of the invention, the peaks 33 and valleys 36 are imparted to the fin material so that approximately the same amount of material resides on each side of a central axis 51. For example, in one embodiment, when the perimeter edge 31 of the fin 19 is facing the viewer, an axis that is mid-way between the peaks 33 of the first major surface 25 and the peaks 33 of the second major surface 28 will have as much mass of the fin 19 on one side of the axis 51 as on the other side of the axis 51. To accomplish such a result, the peaks 33 and valleys 36 may be formed to have a repeating pattern, but the pattern need not be a repeating one. FIG. 2 depicts a fin having a repeating pattern of the primary texture.

[0036]The invention may be embodied as a method of making a heat transfer device. FIG. 4 illustrates one such method. In FIG. 4, a substantially flat thermally-conductive fin material may be provided 100. The fin material may have a first major surface and a second major surface, wherein the major surfaces are spaced apart by a thickness-distance, which is substantially constant. The fin material may be formed 103, for example, by rolling, stamping, embossing or cold-working, to change the thermally-conductive material from flat to non-flat, but once changed, the thickness-distance of the non-flat material is substantially constant. It may be important to note that the invention may be used to make a fin that has a thickness that is relatively large when compared to prior art methods of making fins. The invention can be used to make fins 19 having a thickness-distance 39 that is in the range of 0.005 to 0.125 inches.

[0037]Holes may be formed 106 in the fin material to extend from the first major surface to the second major surface. The holes may be formed 106 by punching, drilling, piercing or some other process. The holes may be formed 106 either before or after the fin material is changed from substantially flat to substantially non-flat.

[0038]Collars may be placed or formed 109 on the fin material to coincide with some of the holes, and a tube may be placed in the collar. The collar may be secured 112 to the tube and/or the fin in order to provide a conductive pathway for transferring heat by conduction. Some of the holes in the fin material may remain open to allow fluid to pass from one side of the fin to the other side of the fin, thereby permitting fluid that has contacted the first major surface to pass through the hole to the second major surface. To secure 112 a collar to the fin and/or a tube, a press-fitting, friction-fitting, tube-expansion, welding, brazing, soldering, or adhesive operation may be carried out.

[0039]Forming 103 the fin material may be carried out to provide peaks and valleys on the major surfaces so that an elevation change from a peak on the first major surface to an adjacent valley on the first major surface is less than the thickness-distance. However, forming 103 the fin material may be carried out to provide peaks and valleys on the major surfaces so that an elevation change from a peak on the first major surface to an adjacent valley on the first major surface is more than the thickness-distance.

[0040]A method according to the invention may include a surface working operation in order to impart desired characteristics to the fin material. For example, the surface working operation may be electro-polishing, pickling, passivation, ionization, sand blasting, chemical treatment, sputtering, spraying, ion deposition, and/or cleaning. It should also be noted that the fin material may be heat-treated (e.g. annealing, quenching, etc.) to impart physical and/or chemical changes to the fin material, and/or work hardened to make the fin stronger.

[0041]The method may include forming flow disrupters on at least one of the major surfaces. The flow disrupters may be provided on the fin material by adding material to the fin material. The flow disrupters may be provided on the fin material by moving portions of the fin material, for example by rolling or stamping.

[0042]The method may include applying a coating to at least one of the major surfaces. For example, the coating may have flow disrupters thereon, thereby resulting in a fin that is not only a composite, but also provides a primary texture and a secondary texture. Other coatings that may be applied may include (a) a material that has the ability to absorb more radiant heat than it emits, (b) a reactive material that chemically combines with substances in the fluid surrounding the fin, (c) a catalytic material that encourages a chemical reaction between substances in the fluid surrounding the fin, (c) a corrosion-resistant material that will prevent corrosion of the fin, (d) a fouling-resistant material to prevent fouling of the fin surface, and/or (e) an anti-bacterial material to prevent bacteria from reproducing. Such coatings may be applied to the fin material electrically or by rolling, or other previously mentioned methods.

[0043]It should be noted that large sheets may be used to create many fins 19. For example, a four-foot by eight-foot sheet of metal may be subjected to the forming operations identified above to create a single large fin, or such a sheet may be cut into smaller pieces to create a plurality of fins 19 from the metal sheet. This may reduce manufacturing costs relative to prior art methods of creating fins. Furthermore, a wide variety of fin shapes may be produced, thereby providing greater flexibility to heat exchanger designers.

[0044]Having provided a description of embodiments of the invention, a particularly interesting embodiment of a heat transfer device according to the invention will now be described. FIG. 5 depicts a fin according to this embodiment. This embodiment has a fin 19 having a primary texture 200 and a secondary texture 203. Each texture 200, 203 has its own average amplitude 48, the amplitude 48 being an elevation change from a peak of the texture to an adjacent valley of that texture. In this embodiment, the average amplitude 48A of the secondary texture is between 1% and 90% of the average amplitude 48B of the primary texture 200. In this manner, two textures 200, 203 are provided to the heat transfer fin 19. It should be noted at this point that the textures 200, 203 may be in a repeating pattern, or a non-repeating pattern.

[0045]The primary texture 200 may be imparted to the fin material in such a manner that the fin has a substantially constant thickness. By doing so, stress points and weaknesses in the fin material may be avoided, and a more rigid fin may be produced.

[0046]The amplitude 48A of the primary texture 200 may be less than a thickness-distance 39 of the fin 19. Alternatively, the amplitude 48A of the primary texture 200 may be more than a thickness-distance 39 of the fin 19. The primary texture 200 may result in having a substantially equal amount of the fin 19 positioned on each side of a central axis 51 of the fin 19, the central axis 51 being a geometric center of the fin 19 when the perimeter edge 31 is facing the viewer.

[0047]At least one of the textures 200, 203 may be created by adding material to the tin 19. But, in other embodiments, at least one of the textures 200, 203 may be imparted by moving portions of the fin material. For example, rolling, cold working, embossing, and/or stamping might be used. Furthermore, at least one of the textures 200, 203 may be imparted by embossing or coating a substrate 206 to create the textured fin 19. For example, the secondary texture 203 may be provided via a coating, and such a coating may be joined to a substrate 206 of the fin 19.

[0048]Holes 16 may be made to extend through the fin 19. The holes 16 may be shaped to have a common geometric shape, such as square, round, oval, rectangular, parallelogram, or triangular. But, the shape of the holes 16 need not be a common geometric shape.

[0049]A tube 13 may extend through one of the holes 16, or several tubes 13 may each extend through a different one of the holes 16. A collar 22 may be used to provide a conductive pathway for transferring heat by conduction from the fin 19 to the tube 13, or vice versa. The collar 22 may be attached to the fin 19 or the tube 13 by press fitting, a friction-fit, expanding the tube 13, or by placing a weld, brazed connection, solder, or adhesive.

[0050]Some of the holes 16A may remain open--that is to say they do not have tubes 13 extending through them. The open holes 16A may be similarly sized, or differently sized. The open holes 16A may have a repeating pattern, or they may be randomly spaced from each other.

[0051]Similar to the embodiments described above, the surface finish and/or coatings of such a fin 19 may be as noted earlier in the description. Also, such a fin 19 may be heat treated and/or work hardened. Finally, such a fin 19 may be a composite of two or more materials, such as a substrate 20 and a coating 21.

[0052]To make such a fin 19, a substantially flat thermally-conductive fin material may be provided 300. The secondary texture may be imparted 303 to the fin material, and then the fin material may be formed 306 by rolling, stamping or cold working to impart a primary texture. The secondary texture may be imparted 303 to the fin material, either prior to or after imparting 306 the primary texture to the fin material. FIG. 6 depicts one such method. In a particularly unique version of such a fin, the primary texture is imparted 306 to the fin material so that the fin material has a substantially constant thickness. However, the invention is not limited to fins having material with a substantially constant thickness. It should be noted that the fin, by virtue of varying the amplitude of the primary surface, may have a varying thickness, while the material making up the fin has a substantially constant thickness.

[0053]A collar may be added by forming a portion of the fin material into a collar, or by providing a separate component in the shape of a collar. The collar may be added to the fin to coincide with one of the holes, and a tube may be placed to extend through the collar. The purpose of the collar is for providing a conductive pathway for transferring heat from the fin to the tube, or from the tube to the fin. If the collar is provided as a distinct part, the collar may be secured to the tube and/or the fin by press fitting the collar, friction-fitting the collar, expanding the tube to the collar, welding, brazing, soldering, or by applying an adhesive.

[0054]Some of the holes in the fin may remain open (they have no tube extending through) to allow fluid to pass through the open hole from a first side of the fin to a second side of the fin. The open holes may be substantially the same size, or differently sized, depending on the desires of the person designing the fin. For example, the heat exchanger designer may select varying hole sizes and spacing to direct more or less flow to certain parts of the heat exchanger in order to achieve desired flow rates and/or heat transfer in particular sections of the heat exchanger.

[0055]Having described the invention, it will now be recognized that heat transfer and flow distribution are dependent on the relative position of the primary and secondary textures 200, 203 of the fin. The shape and density of the textures also may have an effect. The dependence of the flow and heat transfer on the different geometric characteristics of the textured surfaces is important in the heat transfer achieved by this invention. If used alone, the primary texture or the secondary texture may yield an increase in heat transfer, and the increase attributable to using one or the other is usually about the same. However, we have discovered that the combination of a primary and a secondary texture yields an increase in heat transfer that is far greater than the sum that the two (the heat transfer due to the primary texture alone and the heat transfer due to the secondary texture alone). There are additional benefits of postponing fouling in most cases, depending on the fluid and flow conditions.

[0056]The primary texture 200 disrupts the boundary layer farther from the surface of the fin, but there will still be portions of the flow near the fin that may have uniform flow. The secondary texture 203 causes turbulence and mixing near the fin surface, but the mixing does not progress as far into the free stream (as in the case of the primary texture). However, by combining the two types of texture, there is turbulent flow over the entire surface of the fin, and that turbulent flow mixes further into the free stream, which may have the added benefit of providing enhanced turbulence between two adjacent fins. The result is an unexpected enhancement to heat transfer that is more than each texture could yield by itself. In addition, such texturing of the fin produces a more rigid fin.

[0057]Although the present invention has been described with respect to one or more particular embodiments, it will be understood that other embodiments of the present invention may be made without departing from the spirit and scope of the present invention. Hence, the present invention is deemed limited only by the appended claims and the reasonable interpretation thereof.

Claims

1. A heat transfer device, comprising a fin having a primary texture and a secondary texture, wherein each texture has an average amplitude, the amplitude being an elevation change from a peak of the texture to an adjacent valley, and the average amplitude of the secondary texture is between 1% and 90% of the average amplitude of the primary texture.

2. The heat transfer device of claim 1, wherein the fin has a substantially constant thickness.

3. The heat transfer device of claim 1, wherein a plurality of holes extend through the fin.

4. The heat transfer device of claim 3, further comprising a tube extending through one of the holes.

5. The heat transfer device of claim 4, further comprising a collar connected to the fin and the tube to provide a conductive pathway for transferring heat by conduction.

6. The heat transfer device of claim 4, wherein at least one of the holes is open.

7. The heat transfer device of claim 1, wherein the amplitude of the primary texture is less than a thickness-distance of the fin.

8. The heat transfer device of claim 1, wherein the amplitude of the primary texture is more than a thickness-distance of the fin.

9. The heat transfer device of claim 1, wherein the fin has a surface finish created by a process selected from electro-polishing, pickling, passivation, anodizing, sand blasting, chemical treatment, sputtering, spraying, ion deposition, vacuum forming and cleaning.

10. The heat transfer device of claim 1, wherein at least one of the textures is created by adding material to the fin.

11. The heat transfer device of claim 1, wherein at least one of the textures is created by moving portions of the fin material.

12. The heat transfer device of claim 1, wherein at least one of the textures is formed by subjecting the fin to an operation selected from rolling, cold working, stamping and embossing.

13. The heat transfer device of claim 1, wherein at least one of the textures is a repeating pattern.

14. The heat transfer device of claim 1, wherein at least one of the textures is a non-repeating pattern.

15. The heat transfer device of claim 1, wherein at least one of the textures is provided by a coating applied to a substrate.

16. The heat transfer device of claim 1, wherein the fin is heat treated.

17. The heat transfer device of claim 1, wherein the fin is work hardened.

18. The heat transfer device of claim 1, wherein the fin is a composite of two or more materials.

19. The heat transfer device of claim 1, wherein the fin is displaced substantially equally about a geometrically central axis of the fin.

20. A method of making a heat transfer device, comprising:providing a substantially flat thermally-conductive fin material;forming the fin material by rolling, stamping or cold working to impart a primary texture;imparting a secondary texture to the fin material;wherein each texture has an average amplitude, the amplitude being an elevation change from a peak of the texture to an adjacent valley, and the average amplitude of the secondary texture is between 1% and 90% of the average amplitude of the primary texture.

21. The method of claim 20, wherein a thickness-distance of the fin material is not altered by forming the fin material to impart the primary texture.

22. The method of claim 20, further comprising forming holes in the fin material.

23. The method of claim 22, further comprising adding a collar to the fin material, the collar coinciding with one of the holes.

24. The method of claim 23, further comprising placing a tube in the collar.

25. The method of claim 24, further comprising securing the collar to the tube to provide a conductive pathway for transferring heat by conduction.

26. The method of claim 24, wherein at least one of the holes remains open to allow fluid to pass through the open hole from a first side of the fin to a second side of the fin.

27. The method of claim 20, wherein the average amplitude of the primary texture is less than a thickness-distance of the fin.

28. The method of claim 20, wherein the average amplitude of the primary texture is more than a thickness-distance of the fin.

29. The method of claim 20, further comprising working the fin material by a process selected from electro-polishing, pickling, passivation, ionization, sand blasting, chemical treatment, sputtering, spraying, ion deposition, vacuum forming, and cleaning.

30. The method of claim 20, wherein the secondary texture is imparted to the fin material by adding material to the fin.

31. The method of claim 20, further comprising applying a coating to the fin material.

32. The method of claim 31, wherein the coating has the secondary texture.

33. The method of claim 20, further comprising placing a coating material onto the fin material.

34. The method of claim 20, wherein at least one of the textures is created by moving portions of the fin material.

35. The method of claim 20, wherein the secondary texture is imparted by rolling, stamping embossing or cold working the fin material.

36. The method of claim 35, wherein the secondary texture is imparted to the fin material prior to imparting the primary texture to the fin material.

37. The method of claim 20, further comprising heat-treating the fin material.

38. The method of claim 20, further comprising work hardening the fin material.

39. The method of claim 20, wherein the fin material is rolled so as to displace the fin material substantially equally about a substantially central axis of the fin.

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