HEAT EXCHANGER FINS, ASSEMBLIES AND METHODS

Abstract

A bladed heat exchanger fin, tube assemblies in which the fin is installed, and methods of using the fin. The bladed fin includes a collar and a radial portion extending radially from an axis of the collar. The radial portion has a base region adjacent the collar and first and second sets of blades that radially extend therefrom. Each blade has a span-wise axis that is transverse to the axis of the collar. Each of the first set of blades is revolved about the span-wise axis thereof so as to have radial edges that are axially spaced from each other, and each of the second set of blades is not revolved about the span-wise axis thereof. At least some of the blades of the first set are between at least some of the blades of the second set.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/306,140, filed Feb. 19, 2010, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to heat exchangers, and more particularly to fins adapted to be mounted on a heat exchanger tube and configured to promote heat transfer to or from the tube.

Heat exchangers are employed within a variety of industries for transferring heat to or from various types of solids and fluids. As a nonlimiting example, the automotive industry employs heat exchangers in air conditioning systems (condensers and evaporators), engine cooling systems (radiators), and internal climate control systems (heater cores), etc. One type of heat exchanger construction used in the automotive industry for condensers and evaporators comprises a number of parallel tubes that are joined to and between a pair of manifolds, creating a parallel flow arrangement. The ends of the tubes are typically metallurgically joined (brazed, soldered or welded) to tube ports, generally in the form of holes or slots formed in a wall of each manifold.

In order to maximize the amount of surface area available for transferring heat between a fluid (gas and/or liquid) flowing over a heat exchanger tube and a fluid (gas and/or liquid) flowing through the tube, heat exchangers often have a tube-and-fin construction in which numerous tubes thermally communicate with high surface area fins. One type of fin is in the form of a flat panel having multiple apertures through which multiple parallel tubes are individually inserted. Another type of fin is in the form of a sinusoidal center that is positioned between adjacent pairs of tubes. In either case, the resulting tube-and-fin assembly is typically oriented so that the edges of the fins face the fluid (e.g., air) flowing between the tubes, i.e., the fins are oriented transverse to the axis of the tubes on which the fins are attached.

Alternative forms of fins that have been suggested include fins that extend radially from individual heat exchanger tubes. As examples, helical-shaped fins have been proposed that may be integrally formed on the outer surface of a tube, and disk-shaped fins have been proposed that are formed separately and then stacked onto the exterior of a tube. Examples of the latter include U.S. Pat. Nos. 4,538,677, 5,337,807, 5,617,916, 6,234,245, 7,418,848 and 7,743,821. As evident from these documents, various shapes have been proposed for disk-shaped fins, including corrugated, convoluted and ribbed forms typically defined on fins having an otherwise continuous circular-shaped outer perimeter. Disk-shaped fins have also been proposed having a blade-like configuration, in which individual segments extend radially from the central axis of the disk. These segments are generally uniform in size and shape, and may lie entirely in the plane of the disk or be deformed to project out of the disk plane, somewhat similar to blades of a propellor or turbine.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a bladed heat exchanger fin, heat exchanger tube assemblies in which the fin is installed, and methods of using the fin to transfer thermal energy between fluids.

According to a first aspect of the invention, the bladed heat exchanger fin includes a collar having a tubular-shape so as to define an axis and inner and outer surfaces, and a radial portion extending radially from the axis of the collar. The radial portion comprises a base region adjacent the collar and blades that are attached to and radially extend from the base region. The base region defines a base plane that is transverse to the axis of the collar. The blades define an annular array of first and second sets of the blades. The annular array defines a discontinuous perimeter of the bladed heat exchanger fin that is interrupted by gaps between the first and second sets of blades. Each blade of the first and second set of blades has a span-wise axis that is transverse to the axis of the collar. Furthermore, each blade of the first set of blades is revolved about the span-wise axis thereof so as to have oppositely-disposed radial edges that are axially spaced from each other, and each blade of the second set of blades is not revolved about the span-wise axis thereof so as to have oppositely-disposed radial edges that are not axially spaced from each other. At least some of the blades of the first set of blades are between at least some of the blades of the second set of blades.

According to a second aspect of the invention, the bladed heat exchanger fin is one of a plurality of bladed heat exchanger fins installed on a heat exchanger tube to define a heat exchanger tube assembly. The collar of each of the bladed heat exchanger fins contacts and surrounds an exterior surface of the heat exchanger tube. The heat exchanger tube assembly may further include one or more bladeless heat exchanger fin having collars that contact and surround the exterior surface of the heat exchanger tube.

Another aspect of the invention is a method of using a plurality of the bladed heat exchanger fins to transfer thermal energy between two fluids. The method includes installing the bladed heat exchanger fins on a heat exchanger tube so that the collar of each of the bladed heat exchanger fins contacts and surrounds an exterior surface of the heat exchanger tube, flowing a first fluid through an interior passage defined within the heat exchanger tube, and flowing a second fluid through the blades of the bladed heat exchanger fins on the heat exchanger tube. The heat exchanger tube assembly may further include one or more bladeless heat exchanger fin having collars that contact and surround the exterior surface of the heat exchanger tube, and around which the second fluid flows.

A technical effect of the invention is that the bladed heat exchanger fins, alone or in combination with one or more bladeless heat exchanger fins, significantly promote the heat transfer efficiency of a heat exchanger tube in comparison to conventional disk-shaped and helical-shaped cooling fins. In particular, combinations of blades in which some are revolved around their respective pitch axes while others are not have been shown to enhance heat transfer by promoting the diffusion of heat around a heat exchanger tube without creating a damming effect to fluid flow around the tube. An additional benefit is that the use of combinations of bladed and bladeless heat exchanger fins is able to promote the structural strength of the fins, particularly if the heat exchanger tube is subjected to damage from impingement by solid debris and high pressure fluids.

Other aspects and advantages of this invention will be better appreciated from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2 and 3 are axial, side and perspective views, respectively, of a disk-shaped bladed fin in accordance with an embodiment of this invention.

FIGS. 4 and 5 are axial and side views, respectively, of a disk-shaped bladeless fin adapted for use in combination with the bladed fin of FIGS. 1 through 3 in accordance with embodiments of this invention.

FIG. 6 is an exploded perspective view of a fixture for assembling the fins of FIGS. 1 through 3 and optionally the fins of FIGS. 4 and 5 on a heat exchanger tube.

FIG. 7 represents a heat exchanger tube on which bladed fins configured as shown in FIGS. 1 through 3 and bladeless fins configured as shown in FIGS. 4 and 5 have been installed in an alternating pattern to form a fin array.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1, 2 and 3 represent what will be referred to herein as a bladed heat exchanger fin 10. This description is attributed to the fin 10 having blades 24 and 26 that radiate outward from a central axis 14 of the fin 10 to define a perimeter 28 of the fin 10. The fin 10 shown in FIGS. 1 through 3 can also be described as disk-shaped, in that the fin 10 has a generally disk-shaped profile such that the perimeter 28 is generally circular in shape, though it should be apparent that the fin 10 is not required to have circular perimeter 28. The bladed fin 10 is further represented in FIGS. 1 through 3 as having a tubular-shaped collar 12 that defines the axis 14 of the fin 10. The axis 14 will serve as a reference in the following discussion for axial, radial and circumferential directions of the fin 10. As represented in FIGS. 1 through 3, the collar 12 has a cylindrical shape such that it defines cylindrical inner and outer surfaces 16 and 18. However, as used herein the term “tubular” is not limited to circular cross-sectional shapes, but also encompasses other noncircular cross-sectional shapes, for example, rectilinear shapes.

The fin 10 has a radial portion 20 that surrounds the collar 12 and extends radially from the axis 14 of the collar 12. The base region 22 defines or otherwise lies in a plane that is transverse and (as shown in FIGS. 1 through 3) preferably perpendicular to the axis 14 of the collar 12. The radial portion 20 is represented in FIGS. 1 through 3 as also being perpendicular to the axis 14, though it is foreseeable that the radial portion 20 could be transverse to the axis 14 yet disposed at some angle other than ninety degrees to the axis 14. Furthermore, the radial portion 20 could have a conical shape relative to the axis 14. The radial portion 20 includes a base region 22 that is immediately adjacent and surrounds the collar 12, and from which the blades 24 and 26 radially extend. The collar 12 and radial portion 20 (which includes the base region 22 and blades 24 and 26) are represented in FIGS. 1 through 3 as being integrally formed to have a one-piece construction, though it is within the scope of the invention that the collar 12 and radial portion 20 could be separately formed and assembled to form the fin 10. Furthermore, it is foreseeable that the blades 24 and 26 could be separately formed and then attached to the base region 22.

The blades 24 and 26 are arranged on the fin 10 to define an annular array of blades. For purposes of the following discussion, the blades 24 and 26 can be said to define two separate sets of blades, though it is also within the scope of the invention to make use of additional sets of blades. In FIG. 1, the blades 24 and 26 are arranged in an alternating pattern, with each blade 24 being circumferentially disposed between a pair of the blades 26, and vice-versa. The blades 24 and 26 are spaced apart from each other by a radial gap 30, with the result that each blade 24 and 26 defines an oppositely-disposed pair of radial edges 36 and 38, respectively. As a result of the gaps 36, the perimeter 28 of the bladed fin 10 is discontinuous as a result of being interrupted by the gaps 30 between adjacent pairs of blades 24 and 26.

Each blade 24 and 26 can be described as having a span-wise axis 32. As used herein, the span-wise axis 32 of each blade 24 and 26 is preferably equi-distant from the radial edges 36 and 38 of the blade 24 and 26, respectively. Each span-wise axis 32 coincides with a radial 34 of the radial portion 20 of the fin 10. In the embodiment of FIGS. 1 through 3, the span-wise axis 32 of each blade 24 and 26 also lies within the plane defined by the base region 22, and as such is perpendicular to the axis 14 of the collar 12. However, the span-wise axes 32 of the blades 24 and 26 are not required to be perpendicular to the axis 14, and as such could be inclined relative to the axis 14, for example, as a result of the radial portion 20 having a conical shape or otherwise being at an angle other than perpendicular to the axis 14.

The blades 24 and 26 differ from each other in that each blade 24 is revolved about its span-wise axis 32, somewhat similar to the blades of a propellor or turbine, whereas the blades 26 are not. Instead, each blade 26 lies entirely within the plane defined by the base region 22. The junction between the base region 22 and each blade 24 is represented in FIG. 1 as defining a linear crease 40 that is transverse but not perpendicular to a radial 34 of the radial portion 20. In the configuration shown in FIGS. 1 through 3, the span-wise axis 32 of each blade 24 still lies within the plane defined by the base region 22, but the radial edges 36 of each blade 24 are axially spaced from each other. As evident from FIG. 2, because the span-wise axes 32 of the blades 24 lie in the plane defined by the base region 22, the radial edges 36 of the blades 24 are located on opposite sides of the base plane.

Bladed fins 10 of the type shown in FIGS. 1 through 3 are preferably used in combination with multiple other fins, at least some of which having the same configuration as shown in FIGS. 1 through 3. As represented in FIG. 6, these fins 10 can then be installed on a heat exchanger tube 72 to define a heat exchanger tube assembly 70. The collar 12 of each bladed fin 10 contacts and surrounds an exterior surface 74 of the tube 72, and the axis 14 of each collar 12 preferably coincides with the axis 80 of the tube 72.

As represented in FIG. 6, the tube assembly 70 further includes a plurality of bladeless heat exchanger fins 50 of a type represented in FIGS. 4 and 5, such that the fins 10 and 50 define a linear array of fins 10 and 50 on the tube 72. The term “bladeless” is intended to help differentiate the fins 50 of FIGS. 4 and 5 from the fins 10 of FIGS. 1 through 3, in that the bladeless fins 50 lack any discrete radial elements separated by radial gaps, in contrast to the radial blades 24 and 26 of the fins 10 that are separated by the radial gaps 30. As evident from FIGS. 4 and 5, each bladeless fin 50 has a collar 52 that defines an axis 54 of the fin 50, and a radial portion 60 that extends radially from the axis 54 of the collar 12 to define a continuous perimeter 62 (i.e., uninterrupted by gaps). As with the fin 10 of FIGS. 1 through 3, the radial portion 60 of the bladeless fin 50 is represented as being perpendicular to the axis 54, though the radial portion 60 could be disposed at some other transverse angle to the axis 54, as well as have a conical shape. As evident from FIG. 6, the collar 52 of each bladeless fin 50 contacts and surrounds the exterior surface 74 of the tube 72, so that its axis 54 coincides with the axis 80 of the tube 72.

As also evident from FIG. 6, the bladeless fins 50 are disposed between pairs of the bladed fins 10. Though the thermal performance of the tube assembly 70 tends to be reduced somewhat by the presence of the bladeless fins 50, the configuration represented in FIG. 6 promotes the durability of the fins 10 and, therefore, the overall durability of the tube assembly 70. In particular, the bladeless fins 50 help to support their adjacent bladed fins 10 in the event that the tube assembly 70 is subjected to impacts, for example, from solid debris or high-pressure fluids, as can occur with heat exchangers used in automotive applications.

FIG. 6 further represents the tube assembly 70 as being assembled with a manifold 82, as a result of one end of the tube 72 being inserted in a port 84 defined in the manifold 82. Those skilled in the art will appreciate that the opposite end of the tube 72 would also be similarly received in a port of a second manifold. In use, a fluid (gas or liquid) flowing within the manifold 82 would flow through a passage 78 defined by the interior wall 76 of the tube 72. Heat transfer to or from the fluid within the tube 72 occurs as a result of flowing a second fluid (gas or liquid) around the exterior of the tube 72 and, therefore, through the fins 10 and 50 and, in particular, through the blades 24 and 26 of the bladed fins 10. Due to the presence of the blades 24 and 26, and in particular the different orientations of the blades 24 and 26, greater turbulation is achieved within the flow of the second fluid, which in turn promotes heat transfer between second fluid and the fins 10 and 50.

The angle at which the blades 24 are revolved around their respective axes 32 affects the heat transfer efficiency as well as the pressure drop of flow through the fins 10 and 50. A maximal revolution angle will increase turbulation and therefore promote heat transfer, but will also increase the pressure drop of flow through the fins 10 and 50. On the other hand, a minimal angle will decrease the pressure drop through the fins 10 and 50, but also decrease turbulation and therefore reduce the heat transfer of the tube assembly 70. In FIG. 2, the revolution angle of the blades 24 is about 60 degrees to the axis 32. Generally, a suitable range for the revolution angle is about 30 to less than 90 degrees, with a preferred range being about 45 to about 75 degrees.

The fins 10 and 50 and the tube 72 can be formed from a variety of materials, notable but nonlimiting examples of which include aluminum alloys widely used in heat exchanger applications. Those skilled in the art will appreciate that, depending on the size and geometry of the fins 10 and 50 and tube 70 and the type of material used to form the fins 10 and 50 and tube 72, the fins 10 and 50 can be secured to the tube 72 with an interference fit and/or by a bonding method, including metallurgical bonding techniques such as brazing, soldering and welding. FIG. 7 represents one such assembly method as employing a fixture assembly 100 comprising a fin housing subassembly 102 formed by two complementary fin housing members 104 and 106, a tube housing subassembly 108 formed by two complementary tube housing members 110 and 112, and a fin installation subassembly 114 formed by two complementary fin installation members 116 and 118. The fin housing members 104 and 106 have complementary channels 120 that together define a cavity sized to accommodate an array of fins 10 and 50. Similarly, the tube housing members 110 and 112 have complementary channels 122 that together define a cavity sized to accommodate one end of the tube 72, and the fin installation members 116 and 118 have complementary channels 124 that together define a cavity sized to accommodate the opposite end of the tube 72. Finally, the fin installation members 116 and 118 further have complementary semi-cylindrical members 126 that together define a plunger sized to be received in the cavity defined by the fin housing members 104 and 106 for the purpose of forcing the fins 10 and 50 onto the tube 72, such that the fins 10 and 50 can be retained on the tube 72 by an interference fit. Other fixtures and methods for assembling the fins 10 and 50 on the tube 72 could also be employed.

Those skilled in the art will also appreciate that an optimal cross-section, size and length of the tube 72, an optimal cross-section, size and length of each blade 24 and 26, and an optimal number and distribution of the fins 10 and 50 on the tube 72 will depend on the particular application for which the tube assembly 70 is intended. In addition to air-conditioning applications such as condensers and evaporators, other applications for the present invention include, but are not limited to, engine cooling systems (radiators), internal climate control systems (heater cores), oil coolers, and exhaust gas heat exchangers.

While the invention has been described in terms of specific embodiments, it is apparent that other forms could be adopted by one skilled in the art. Therefore, the scope of the invention is to be limited only by the following claims.

Claims

1. A bladed heat exchanger fin comprising:

a collar having a tubular-shape so as to define an axis and inner and outer surfaces;

a radial portion extending radially from the axis of the collar, the radial portion comprising a base region adjacent the collar and blades that are attached to and radially extend from the base region, the base region defining a base plane that is transverse to the axis of the collar, the blades defining an annular array comprising first and second sets of the blades that define a discontinuous perimeter of the bladed heat exchanger fin that is interrupted by gaps between the first and second sets of blades, each blade of the first and second set of blades having a span-wise axis that is transverse to the axis of the collar;

each blade of the first set of blades being revolved about the span-wise axis thereof so as to have oppositely-disposed radial edges that are axially spaced from each other;

each blade of the second set of blades not being revolved about the span-wise axis thereof so as to have oppositely-disposed radial edges that are not axially spaced from each other; and

at least some of the blades of the first set of blades being between at least some of the blades of the second set of blades.

2. The bladed heat exchanger fin according to claim 1, wherein the base plane is perpendicular to the axis of the collar.

3. The bladed heat exchanger fin according to claim 1, wherein the span-wise axis of each blade of the first and second sets of blades is perpendicular to the axis of the collar and coincides with a radial of the radial portion.

4. The bladed heat exchanger fin according to claim 1, wherein the radial edges of the first set of blades are located on opposite sides of the base plane.

5. The bladed heat exchanger fin according to claim 1, wherein the radial edges of the second set of blades are located within the base plane.

6. The bladed heat exchanger fin according to claim 1, wherein the span-wise axis of each blade of the first set of blades lies within the base plane.

7. The bladed heat exchanger fin according to claim 1, wherein each blade of the second set of blades lies entirely within the base plane.

8. The bladed heat exchanger fin according to claim 1, wherein each blade of the first set of blades adjoins the base region to define a linear crease that is transverse but not perpendicular to a radial of the radial portion.

9. The bladed heat exchanger fin according to claim 1, wherein each blade of the first set of blades is between a pair of the blades of the second set of blades.

10. The bladed heat exchanger fin according to claim 1, wherein the bladed heat exchanger fin is one of a plurality of bladed heat exchanger fins according to claim 1 that are installed on a heat exchanger tube to define a heat exchanger tube assembly, the collar of each of the bladed heat exchanger fins contacts and surrounds an exterior surface of the heat exchanger tube.

11. The heat exchanger tube assembly according to claim 10, wherein the heat exchanger tube assembly further comprises a bladeless heat exchanger fin comprising a collar that contacts and surrounds the exterior surface of the heat exchanger tube, an axis that coincides with the axis of the heat exchanger tube, and a radial portion that extends radially from the collar to define a continuous perimeter of the bladeless heat exchanger fin, the bladeless heat exchanger fin being disposed between a pair of the bladed heat exchanger fins.

12. The heat exchanger tube assembly according to claim 10, wherein the heat exchanger tube is assembled with a pair of manifolds and opposite ends of the heat exchanger tube are received in ports in the manifolds.

13. A method of using a plurality of bladed heat exchanger fins each according to claim 1, the method comprising:

installing the bladed heat exchanger fins on a heat exchanger tube so that the collar of each of the bladed heat exchanger fins contacts and surrounds an exterior surface of the heat exchanger tube;

flowing a first fluid through an interior passage defined within the heat exchanger tube; and

flowing a second fluid through the blades of the bladed heat exchanger fins on the heat exchanger tube.

14. The method according to claim 13, the method further comprising installing a plurality of bladeless heat exchanger fins on the heat exchanger tube, each of the bladeless heat exchanger fins comprising a collar that contacts and surrounds the exterior surface of the heat exchanger tube, an axis that coincides with the axis of the heat exchanger tube, and a radial portion that extends radially from the collar to define a continuous perimeter of the bladeless heat exchanger fin, at least some of the bladeless heat exchanger fins being disposed between pairs of the bladed heat exchanger fins.

15. A bladed heat exchanger fin comprising:

a collar having a tubular-shape so as to define an axis and inner and outer surfaces;

a radial portion extending radially from the axis of the collar, the radial portion comprising a base region adjacent the collar and blades that are attached to and radially extend from the base region, the base region defining a base plane that is perpendicular to the axis of the collar, the blades defining an annular array comprising first and second sets of the blades that define a discontinuous perimeter of the bladed heat exchanger fin that is interrupted by gaps between the first and second sets of blades, each blade of the first and second sets of blades having a span-wise axis that is perpendicular to the axis of the collar and coincides with a radial of the radial portion;

each blade of the first set of blades being revolved about the span-wise axis thereof so that the span-wise axis of each blade of the first set of blades lies within the base plane and each blade of the first set of blades has oppositely-disposed radial edges that are axially spaced from each other and located on opposite sides of the base plane;

each blade of the second set of blades not being revolved about the span-wise axis thereof and each blade of the second set of blades lying entirely within the base plane; and

each blade of the first set of blades being between a pair of the blades of the second set of blades.

16. The bladed heat exchanger fin according to claim 15, wherein each blade of the first set of blades adjoins the base region to define a linear crease that is transverse but not perpendicular to a radial of the radial portion.

17. The bladed heat exchanger fin according to claim 15, wherein the bladed heat exchanger fin is one of a plurality of bladed heat exchanger fins according to claim 15 that are installed on a heat exchanger tube to define a heat exchanger tube assembly, the collar of each of the bladed heat exchanger fins contacts and surrounds an exterior surface of the heat exchanger tube, and the axis of each of the collars coincides with an axis of the heat exchanger tube.

18. The heat exchanger tube assembly according to claim 17, wherein the heat exchanger tube assembly further comprises a plurality of bladeless heat exchanger fins, each of the bladeless heat exchanger fins comprising a collar that contacts and surrounds the exterior surface of the heat exchanger tube, an axis that coincides with the axis of the heat exchanger tube, and a radial portion that extends radially from the collar to define a continuous perimeter of the bladeless heat exchanger fin, at least some of the bladeless heat exchanger fins being disposed between pairs of the bladed heat exchanger fins.

19. The heat exchanger tube assembly according to claim 18, wherein the heat exchanger tube is assembled with a pair of manifolds and opposite ends of the heat exchanger tube are received in ports in the manifolds.

20. A method of using a plurality of bladed heat exchanger fins each according to claim 15, the method comprising:

installing the bladed heat exchanger fins on a heat exchanger tube so that the collar of each of the bladed heat exchanger fins contacts and surrounds an exterior surface of the heat exchanger tube and the axes of the collars coincide with an axis of the heat exchanger tube;

flowing a first fluid through an interior passage defined within the heat exchanger tube; and

flowing a second fluid through the blades of the bladed heat exchanger fins on the heat exchanger tube.

21. The method according to claim 20, the method further comprising installing a plurality of bladeless heat exchanger fins on the heat exchanger tube, each of the bladeless heat exchanger fins comprising a collar that contacts and surrounds the exterior surface of the heat exchanger tube, an axis that coincides with the axis of the heat exchanger tube, and a radial portion that extends radially from the collar to define a continuous perimeter of the bladeless heat exchanger fin, at least some of the bladeless heat exchanger fins being disposed between pairs of the bladed heat exchanger fins.