US20150047820A1

US20150047820A1 - Bendable heat exchanger

Info

Publication number: US20150047820A1
Application number: US14/197,946
Authority: US
Inventors: William E. Rhoden
Original assignee: Hamilton Sundstrand Corp
Current assignee: Hamilton Sundstrand Corp
Priority date: 2013-08-14
Filing date: 2014-03-05
Publication date: 2015-02-19

Abstract

A heat exchanger for disposition within a duct having a curved surface is provided and includes a frame formed to define an inlet, an outlet and an interior by which the inlet and outlet are fluidly communicative, the frame including first and second surfaces having curvatures similar to that of the curved surface on either side of the interior and a heat exchanger fin disposed in the interior, the fin having corrugations and being formed to define slots transverse to the corrugations such that the fin is bendable along the curvatures of the first and second surfaces.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is U.S. Non-Provisional of U.S. Provisional Application No. 61/865,765 filed Aug. 14, 2013, the disclosures of which are incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to heat exchangers and, more particularly, to bendable heat exchangers including a slotted fin.
Turbine engines utilize heat exchangers to manage thermal loads for the engine and aircraft. Heat exchangers are typically rectangular in shape and are fitted as best they can be into an arc sector in a fan duct. The resultant square peg in the round hole configuration leaves the package with unused volume that cannot be utilized by the heat exchanger.
Plate fin air/air heat exchangers present particular issues as at least one or more of the layers cannot be curved because of the orientation of the fins in parallel with the bend curvature. Fins are made by corrugating a piece of flat sheet metal. And curvature is easily achieved by bending the fins along the corrugation axis. Bending is difficult if not impossible to achieve, however, along the fin backbone. Heating the material to achieve bending is possible but control of the bend is difficult to maintain at temperatures near the melting point of the material.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a heat exchanger for disposition within a duct having a curved surface is provided and includes a frame formed to define an inlet, an outlet and an interior by which the inlet and outlet are fluidly communicative, the frame including first and second surfaces having curvatures similar to that of the curved surface on either side of the interior and a heat exchanger fin disposed in the interior, the fin having corrugations and being formed to define slots transverse to the corrugations such that the fin is bendable along the curvatures of the first and second surfaces.
According to another aspect of the invention, a heat exchanger fin is provided and includes a sheet of fin material having a first axis defined along a planned fin backbone and a second axis defined transversely to the planned fin backbone. The sheet is formed to define slots along the second axis such that the slots are transverse to the first axis and the planned fin backbone and includes corrugations along the second axis and the slots.
According to yet another aspect of the invention, a method of assembling a heat exchanger is provided and includes forming fin material into a sheet having a first axis defined along a planned fin backbone and a second axis defined transversely to the planned fin backbone, machining slots in the sheet along the second axis such that the slots are transverse to the first axis and the planned fin backbone and corrugating the sheet along the second axis to form a corrugated sheet with corrugations provided along the slots.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an axial view of a heat exchanger in a duct in accordance with embodiments;

FIG. 2 is a cross-sectional view of the heat exchanger of FIG. 1 taken along line 2-2 of FIG. 1;

FIG. 3 is a plan view of a sheet of fin material with slots in accordance with embodiments;

FIG. 4 is a cross-sectional view of the sheet of FIG. 3 with corrugations; and

FIG. 5 is an axial view of the sheet with corrugations and a bend.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

A heat exchanger with a potential for fin curvature in either the X or Y direction is provided and may be employed to realize a curved heat exchanger using plate-fin manufacturing methods. As will be discussed below, a flat piece of sheet metal is machined to enable curvature along the fin backbone axis. Prior to corrugation, cuts are machined perpendicular to the planned fin backbone such that the fin backbone bisects the machined cut. Once the array of cuts are made, the sheet is corrugated using normal processes. The result is a fin that is segmented and capable of being curved into an arc that effectively stretches the fin backbone. Wider cuts can be made into the pre-formed sheet metal to enable curvature toward the fin backbone if desired. The ability to curve fins in both the X and Y axes at the same time enables more efficient utilization of arc sector volumes that exist in engine core and fan ducts today where packaging concerns are a major concern for engine designers.
With reference to FIG. 2, a heat exchanger 10 is provided. The heat exchanger 10 may be disposed within, for example, a duct 11, such as a duct of an aircraft intake engine. As shown in FIG. 1, the duct 11 has a curved, inward facing surface 110. The curved, inward facing surface 110 may be but is not required to be cylindrical or at least elongate in an axial direction where the curvature is defined transversely to the axial dimension. In any case, the duct 11 includes an upstream section 12, a downstream section 13 and an intermediate section 14, which is fluidly interposed between the upstream section 12 and the downstream section 13, such that the curved, inward facing surface 110 defines a fluid pathway 15. The heat exchanger 10 is disposed within the intermediate section such that fluid flow along the fluid pathway 15 from the upstream section 12 to the downstream section 13 flows through the heat exchanger 10. This flow of fluid through the heat exchanger 10 results in heat transfer between the fluid and another fluid and/or a heat exchanger fin 30 to be described below.
The heat exchanger 10 includes a frame 20 and the above-noted heat exchanger fin 30 (see FIGS. 3-5). The frame 20 is formed to define an inlet 21, an outlet 22 and an interior 23 by which the inlet 21 and the outlet 22 are fluidly communicative. The frame 20 includes a first surface 24 and a second surface 25 on either side of the interior 23. At least one of the first and second surfaces 24, 25 (i.e., first surface 24) abuts and lies against the curved, inward facing surface 110 of the duct 11 such that the heat exchanger 10 is disposed to extend across at least a portion of a span of the fluid pathway 15. In this position, the heat exchanger 10 is disposed to be receptive of at least a portion of the fluid flow proceeding through the fluid pathway 15 via the inlet 21 and is further disposed to exhaust the portion of the fluid flow via the outlet 22. Thus, the portion of the fluid flow 15 proceeds through the interior 23 and, in so doing, passes over and thermally communicates with the heat exchanger fin 30.
In order to save space within the duct 11, to increase an aerodynamic performance of the duct 11 and to permit the heat exchanger 10 to fit tightly within the duct 11 with little to no space between the curved, inward facing surface 110 and the heat exchanger 10, the first surface 24 and, in some cases, the second surface 25 may have a curvature C_HEXthat is similar to a curvature C_Dof the curved, inward facing surface 110 on either side of the interior 23. Thus, the heat exchanger 10 is configured to be inserted and disposed in the duct 11 with little to no space between the heat exchanger 10 and the curved, inward facing surface 110.
With reference to FIGS. 3-5, the heat exchanger fin 30 is disposed in the interior 23. The heat exchanger fin 30 may be formed of a metal, a metallic alloy or another thermally conductive material and includes flanges 31 at either longitudinal end thereof and further includes corrugations 32 between the flanges 31. The heat exchanger fin 30 is further formed to define slots 33 that extend along the corrugations 32. As shown in FIG. 4, the flanges 31 may be substantially co-planar and cooperatively establish a baseline z-axis plane of the heat exchanger fin 30. Of course, it is understood that the flanges 31 need not be co-planar with one another and may in such cases establish two different baseline z-axis planes.
The corrugations 32 are folds in the heat exchanger fin 32 that extend in the z-axis from the baseline z-axis plane. As fluid flow proceeds through the interior 23 of the heat exchanger 10, the corrugations 32 aerodynamically interact with the fluid flow to cause turbulation that increases a degree of heat transfer or heat removal from the fluid. Thus, each corrugation 32 includes a first seam 320, a first leg 321, a second seam 322, a second leg 323 and third seam 324. The first, second and third seams 320, 322 and 324 extend in a first or x-axis (see FIG. 3) and are substantially straight. The second seam 322, in particular, may form a fin backbone 40 that extends along the x-axis and is transverse or, in some cases, perpendicular to a second or y-axis and to a third or the z-axis.
The slots 33 are oriented transversely or, in some cases, perpendicularly with respect to the corrugations 32. The slots 33 extend along the y-axis and are respectively associated with a single corrugation 32. That is, as shown in FIG. 3, the left-side corrugation 32 is associated with 18 slots and the right-side corrugation 32 is similarly associated with 18 slots 33. The “left-side slots” do not extend into or otherwise reach or communicate with the “right-side slots” and vice versa. Although the corrugations 32 illustrated in FIG. 3 are each associated with equal numbers of slots 33, it is to be understood that this is not necessary and that each corrugation 32 may be associated with a unique number of slots 33. The unique number of slots 33 may be based on, for example, an amount of curvature required to be accounted for as discussed below.
In a conventional heat exchanger fin that has corrugations but not slots, the corrugations prevent the heat exchanger fin from being bent in the x-axis (or an equivalent axis). In accordance with embodiments, however, and, as shown in FIG. 5, the slots 33 permit the heat exchanger fin 30 to be bendable along the x-axis. As a result of such bending, the tips 34 of the corrugations 32 between adjacent slots 33 separate from one another by a degree that is directly related to an amount the heat exchanger fin 30 is bent. That is, the greater the bending, the greater the separation of the tips 34.
With reference back to FIG. 2, the heat exchanger fin 30 may be disposable within the interior 23 of the heat exchanger 10 such that the slots 33 extend longitudinally along the axial dimension of the duct 11 (i.e., in and out of the image in FIG. 2) and the corrugations 32 extend radially (i.e., vertically within the plane of the image in FIG. 2).
In accordance with further aspects, a method of assembling the heat exchanger 10 is provided. The method includes forming fin material into a sheet having the first or x-axis defined along the planned fin backbone 40 and the second or y-axis defined transversely to the planned fin backbone 40, machining the slots 33 in the sheet along the second axis such that the slots 33 are transverse to the first axis and the planned fin backbone and forming the corrugations 32. The forming of the corrugations 32 includes corrugating or folding the sheet along the second axis. The method may further include bending the sheet along the first axis such that the sheet can be easily fit into the heat exchanger 10 and the duct 11.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claims

1. A heat exchanger for disposition within a duct having a curved surface, the heat exchanger comprising:

a frame formed to define an inlet, an outlet and an interior by which the inlet and outlet are fluidly communicative, the frame including first and second surfaces having curvatures similar to that of the curved surface on either side of the interior; and

a heat exchanger fin disposed in the interior, the fin having corrugations and being formed to define slots transverse to the corrugations such that the fin is bendable along the curvatures of the first and second surfaces.

2. The heat exchanger according to claim 1, wherein the slots and corrugations are perpendicular.

3. The heat exchanger according to claim 1, wherein the fin comprises a metal or metallic alloy.

4. A heat exchanger fin, comprising:

a sheet of fin material having a first axis defined along a planned fin backbone and a second axis defined transversely to the planned fin backbone;

the sheet being formed to define slots along the second axis such that the slots are transverse to the first axis and the planned fin backbone; and

the sheet including corrugations along the second axis and the slots.

5. The heat exchanger fin according to claim 4, wherein the sheet is bendable along the first axis.

6. The heat exchanger fin according to claim 4, wherein the first and second axes are perpendicular.

7. The heat exchanger fin according to claim 4, wherein the slots and corrugations are perpendicular.

8. The heat exchanger fin according to claim 4, wherein the fin material comprises a metal or metallic alloy.

9. A method of assembling a heat exchanger, the method comprising:

forming fin material into a sheet having a first axis defined along a planned fin backbone and a second axis defined transversely to the planned fin backbone;

machining slots in the sheet along the second axis such that the slots are transverse to the first axis and the planned fin backbone; and

corrugating the sheet along the second axis to form a corrugated sheet with corrugations provided along the slots.

10. The method according to claim 9, further comprising bending the sheet along the first axis.

11. The method according to claim 9, wherein the first and second axes are perpendicular.

12. The method according to claim 6, wherein the slots and corrugations are perpendicular.

13. The method according to claim 9, wherein the fin material comprises a metal or metallic alloy.