GB2416723A

GB2416723A - Manufacture of Aluminium based heat transfer panels

Info

Publication number: GB2416723A
Application number: GB0523151A
Authority: GB
Inventors: David Birkett
Original assignee: ADAL INNOVATION Ltd
Current assignee: ADAL INNOVATION Ltd
Priority date: 2005-11-14
Filing date: 2005-11-14
Publication date: 2006-02-08
Anticipated expiration: 2025-11-14
Also published as: GB0523151D0; GB2416723B

Abstract

The invention provides a method of manufacturing a heat transfer panel. A copper pipe 1 is used to line the inner bores of a number of extruded aluminium panel sections 2 to 5 and is expanded within each inner bore by the application of hydraulic pressure. The copper pipe expands within the inner bore within its plastic deformation range, and transmits a pressure to the inner bore to expand the inner bore within its elastic deformation range. The expansion is created by the application of internal hydraulic pressure, but only after clamping all portions of the copper pipe which extend out of the inner bore or bores. Expansion of those clamped portions is confined to its elastic range, so that there is no work-hardening of the copper pipe other than that portion that is expanded into contact with the respective inner bores. The pipe can then be bent into a sinusoidal formation, and made up into a composite ceiling heat transfer panel.

Description

24 1 6723

TITLE

Manufacture of Aluminium Based Heat Transfer Panels

DESCRIPTION

Field of the Invention

The invention relates to the manufacture of heat transfer panels from aluminium or from an aluminium alloy.

Background Art

Aluminium is the second most widely used metal after iron. In comparison to many other metals, it and its alloys are extremely lightweight, are very resistant to corrosion and exhibit excellent heat conductivity. These specific properties make the base metal and its alloys desirable materials to use in the manufacture of heat transfer panels.

For ease of reference, throughout this Specification the term "aluminium based" refers to pure aluminium or an aluminium alloy; and similarly the term "copper based" refers to pure copper, a copper alloy or alternatives to copper with similar properties.

Most commonly, aluminium based components are produced as extrusions.

The basic raw material is generally in the form of a billet which is heated up to a temperature of between 450 and 500 to form a heated bar which is passed through a dye to give the finished extrusion. Whilst this process is capable of producing an extrusion of unlimited length, the extrusion will generally have a limited width, typically about 150 to 200 mm. That is not generally sufficient for a heat transfer panel, and aluminium based heat transfer panels have been proposed which comprise a plurality of extrusions closely abutting one another along their length and mutually joined side by side. To give such a composite panel a heat transfer capacity, copper based pipes are secured to the composite panel in good heat exchange relationship with the aluminium based material, for example by welding. In use a heat : ë : e: : : :. e

e e ce. ese e - 2 transfer fluid can be carried in the copper based pipes so as to transfer heat to or from the panel.

Instead of joining the copper based pipes to the composite aluminium panel by welding, US-A-6082353 discloses a method of making a solar collector panel by lining an inner bore in a panel of an aluminium-based material with a copper-based tube, and expanding the tube by passing a plug or bullet along the length of the tube to expand it. The metal tube is expanded in its plastic deformation range, whereas the inner bore of the panel of aluminium based 0 material is expanded to a lesser extent, in its elastic deformation range. The result is that after expansion the aluminium-based panel grips the metal tube tightly, to create a good heat transfer therebetween and to exclude moisture from the junction between the tube and the inner bore of the panel, which could create a site of galvanic corrosion.

GB-A-2376431 discloses a similar method of connecting together the panel of aluminium-based material and the metal lining tube by expanding the lining tube within the inner bore of the aluminium panel. According to GBA 2376431 the inner bore is established along the junction between two side- by side adjacent panels with the bore being created by the juxtaposition of two edge mouldings of the adjacent panels. The expansion of the metal tube may be obtained not by passing a plug or bullet along the length of the tube to expand it, but by applying an internal hydraulic pressure to the tube, sufficient to cause it to expand radially outwardly into its plastic deformation range, until it positively engages with the interlocking components of the two adjacent panels which together define the inner bore. As with US-A-6082353, expansion of the copper-based tube establishes good heat transfer between the tube and the inner bore of the aluminium-based heat transfer panel, and excludes moisture therebetween so as to minimise corrosion.

Another feature of the expansion of the copper based tube is that the expansion into its plastic deformation range causes it to work-harden. That e e e e ë e e e e e e e e e a work-hardening is an advantage insofar as the copper based tube becomes locked into the inner bore of the composite aluminium-based heat transfer panel, but has the disadvantage that the copper-based tube cannot subsequently be bent and worked, as it has lost the ductility which was a characteristic of the copper-based material before its expansion and work- hardening.

The expansion methods of both US-A-6082353 and GB-A-2376431 create an expansion of the entire copper-based tube from one end to the other. If the ends of the tube extend out from the inner bore of the aluminium heat transfer panel, then those extending ends increase in size along with the remainder of the tube and become work-hardened. It is then difficult to secure pipe fittings to those exposed tube ends because the size will not be the same as before expansion, and the workability of the metal after work-hardening will make it difficult to create a good seal with a pipe connector. Moreover the copper based tube cannot be re-shaped or bent after the expansion step, which is a serious inconvenience to the plumber making the final installation.

The present invention provides a method of manufacturing heat transfer panels which avoids the above problems and which in its preferred embodiments creates a composite aluminium heat transfer panel with economics of manufacture and heat transfer properties well in excess of those currently available.

The Invention The invention provides a method for constructing a heat transfer panel from extruded aluminium based sections, as defined in claim 1 herein.

The expansion of the copper based pipe within the inner bore of the one or more panels of extruded aluminium based material must be by the application of hydraulic pressure as taught in GB-A-2376431, as the use of a plug or bullet as taught in US-A-6082353 would require the passage of the plug or e e - 4 bullet along the complete length of the copper based pipe, including those portions which extend out of the inner bore. The clamping of the portions of the pipe which extend out of the inner bore is preferably achieved by a clamping means which may for example comprise a pair of opposed jaws which simply clamp around the exposed portions of the pipe which extend from the inner bore immediately before those lining portions of the copper based pipe are expanded by the application of hydraulic pressure.

Preferably a continuous single length of the copper based pipe is used to line the inner bores of a plurality of extruded panels of aluminium based material.

Portions of that copper based pipe at opposite ends of the adjacent extruded panels are clamped before internal pressurization, as are the intermediate portions of the copper based pipe between each pair of adjacent extruded panels. Either before or after, but preferably after, the expansion of the copper based pipe within the inner bores, the pipe may be bent into a sinusoidal formation to bring adjacent extruded panels into side-by-side array.

Those extruded panels in side-by-side array are then preferably adhered to an aluminium face sheet, which is optionally surrounded by and supported by an edge frame of aluminium, using a heat transfer adhesive. A thermally insulating material, such as mat of 30 mm thick Celotex _. GA3000Z low density rigid polyisocyanurate foam board is preferably laminated with oil/kraft paper/foil on both sides, is placed within that edge frame to overlie the array of extruded panels, to restrict heat transfer from the extruded panels of aluminium based material other than to and through the aluminium base sheet.

Heat transfer panels according to the invention can be made up as ceiling panels, as wall radiators, or as skirting level or ceiling coving radiators. The ceiling panels or wall radiators are preferably made into modular sizes.

Typical sizes would be 600 x 600 mm; 600 x 900 mm; 600 x 1200 mm; 600 x 1800 mm; 600 x 2400 mm and 600 x 3000 mm. The copper based pipe is suitably conventional 8 mm diameter annealed copper pipe.

e: . .: .: .e:e he . . . * . .. * . . - 5 Because of the light weight of the heat transfer panels made according to the invention, they are particularly suitable for ceiling mounting. Such ceiling panels can be supported using a beam clamp suspension bracket with a minimum of four clamps per panel, to create a suspended ceiling through which hot or cold water can be passed to provide a highly efficient and yet unobtrusive heating or cooling system for the interiors of buildings.

Drawings 0 Figure 1 is a plan view from above of a ceiling panel according to the invention, with the insulation which normally would overlie the extruded aluminium based panels being removed; Figure 2 is a sectional side view of the panel of Figure 1; Figure 3 is a sectional end view of the panel of Figure 1; Figure 4 is an enlarged cross section through one of the panels of extruded aluminium based material used in the panel of Figure 1; Figure 5 is a schematic diagram illustrating the clamping of the copper based pipe used to create the panel of Figure 1 prior to its expansion in the inner bores of the panels of extruded aluminium based material; Figure 6 is a schematic diagram illustrating the bending sequence to progress from the layout of Figure 5 to that of Figure 1; and Figure 7 is a plan view from above similar to that of Figure 1 but through another panel according to the invention which incorporates manifolds for connection to the copper pipe.

Referring first to Figures 1 to 3, both show a heat transfer panel for use as a ceiling panel, in which an 8 mm copper tube 1 is bent into a sinusoidal form, for parallel straight sections which pass through the respective inner bores of four extruded aluminium based panels 2 to 5. Those panels 2 to 5 are adhered to an aluminium face sheet 6 using a heat transfer adhesive (not shown), and the aluminium face sheet 6 is supported by or may even be formed integrally with an edge frame 7. Figure 2 shows a layer of a thermally c ce. ë e e e e - 6 insulating board 8 placed over the four aluminium based extrusions 2 to 5, although that thermal insulation board 8 is omitted from Figures 1 and 3 simply in the interests of clarity.

The cross-sectional shape of each of the four aluminium based extruded panels 2 to 5 is the same, and is shown enlarged in Figure 4 for the extrusion 2.

The method of manufacturing the ceiling heat transfer panel of Figures 1 to 3 0 is illustrated in Figures 5 and 6. The copper based pipe 1 is initially straight, and is threaded through the inner bores of the extruded panels 2 to 5 which are arranged mutually in line. The extruded panels are spaced apart, and around each exposed length of copper based pipe 1 which passes between adjacent but mutually spaced extrusions there is placed a clamp 9. Clamp 9 has opposed jaws which when brought together define an 8 mm bore which fits closely around the intermediate length of copper pipe 1. Those opposed jaws 9 prevent the expansion of the copper based pipe into its plastic deformation range during the subsequent expansion step to be described.

Similar clamping members (not shown) are placed around the two extreme ends of the copper based pipe 1 as it enters the first aluminium extruded panel 2 and as it exists the last aluminium extruded panel 5. In Figure 5, however, these additional clamping members are omitted so that the pipe 1 can clearly be seen.

One end of the pipe 1 is capped (not illustrated) and the other end is connected to a source of hydraulic pressure. After all of the clamps 9 have been tightened, the hydraulic pressure internally of the pipe 1 is increased to about 20 MPa (3000 p.s.i.) which is sufficient to cause expansion of the pipe 1. Where the pipe 1 passes through the clamps 9 its expansion is curtailed so that it does not expand beyond its elastic range. That means that on the release of the hydraulic pressure the pipe relaxes back to its original diameter # . . a - 7 and is not work-hardened. Where the pipe passes through the aluminium extrusions 2 to 5, however, its expansion continues into the plastic range until it bears hard against the inner wall of the wall formed in each of the aluminium extrusions 2 to 5. The aluminium extrusions 2 to 5 will themselves experience some degree of expansion because of the pressure of the pipe wall, but that is confined to the elastic range. The expansion of the pipe 1 is sufficient to bring it into intimate metal to metal contact with the whole of the inner bore of each extruded section, pushing into minor depressions and accurately following the microscopic roughness of the extruded material forming the 0 extruded panels 2 to 5. On relaxation of the hydraulic pressure, the copper pipe 1 within the extruded sections 2 to 5 is work-hardened, is rigidly connected to the extruded sections, and is in an excellent state of thermal conductivity therewith. The portions of the pipe 1 extending outwardly from the extruded sections 2 to 5, as illustrated in Figure 6 are not however work hardened and can be bent to bring the linear arrangement of Figure 6 into the sinusoidal configuration of Figure 1. The sequence of bending is illustrated in Figure 6, with the final two bends of the eight stage sequence being to bend the tails of the pipe upwardly as shown in Figure 3. The aluminium extruded panels 2 to 5 are adhered to the aluminium face sheet 6 after completion of the above bending sequence, and the resulting product is a ceiling heat transfer panel that can be used in fixed or suspended ceilings to convey heating or cooling fluid such as hot or cold water along the pipe 1, to give an excellent and unobtrusive climate control in a building.

Figure 1 shows a single pipe length 1 passing through all four extruded panels 2 to 5. Many alternative configurations are possible, one being as illustrated in Figure 7 in which each pipe 1 passes through 1 long extruded section only, and manifolds 10 are used to direct the single cooling liquid through pairs of extruded panels 2 and 3 in parallel.

Claims

ë e. .e ee e - 8 CLAIMS

1. A method of manufacturing a heat transfer panel from extruded aluminium based material in which a copper based pipe for circulating heat- exchange liquid is used to line an inner bore formed in one or more panels of the extruded aluminium based material, the copper based pipe being expanded within the inner bore in its plastic deformation range to bring it into close physical and thermal contact with the wall of the inner bore and thereby to expand the inner bore in its elastic deformation range, characterized in that before expansion of the copper- based pipe all portions of the pipe which 0 extend out of the inner bore are clamped between mutually opposed clamping members which restrict the permitted expansion of the said extending portions to the elastic deformation range of the pipe material, and then the pipe expansion is achieved by imposing an internal hydraulic pressure within the pipe to cause the expansion of the unclamped portions lining the inner bore.

2. A method of manufacturing a heat transfer panel according to claim 1, wherein the hydraulic pressure imposed to cause expansion of the copper based pipe within the inner bore of the one or more aluminium based panels is a pressure of at least 20 MPa (3000 p.s.i.)

3. A method of manufacturing a heat transfer panel according to claim 2, wherein the copper based pipe is annealed copper.

4. A method of manufacturing a heat transfer panel according to claim 3, wherein a single continuous length of the copper based pipe is used to line the inner bores of a plurality of extruded panels of aluminium based material, with a portion of the copper based pipe between each pair of adjacent extruded panels extending out from the inner bores of those panels and being clamped to restrict the permitted expansion of those extending portions during the expansion of the remainder of the copper based pipe within the inner bores.

* 6 " ' ' .

5. A method of manufacturing a heat transfer panel according to claim 4, wherein the copper based pipe is bent into a sinusoidal formation to bring adjacent extruded panels into side-by-side formation before or after the expansion of the copper based pipe within the inner bores.

6. A method of manufacturing a heat transfer panel according to claim 5, wherein the extruded panels in side-by-side formation are adhered to an aluminium face sheet using a heat transfer adhesive after the expansion of the copper based pipe within the inner bores.

7. A method of manufacturing a heat transfer panel according to claim 6, wherein the aluminium face sheet is surrounded by an edge frame of aluminium.

8. A method of manufacturing a heat transfer panel according to claim 7, wherein the edge frame is filled with a thermally insulating material to restrict heat transfer from the extruded panels of aluminium based material other than to and through the aluminium face sheet.

9. A heat transfer panel made according to any preceding claim.

10. A heat transfer panel according to any of claims 5 to 8, wherein the individual adjacent extruded panels are mutually spaced but coplanar in their side-by-side configuration.