GB2385910A

GB2385910A - Solar heating panel

Info

Publication number: GB2385910A
Application number: GB0202478A
Authority: GB
Inventors: Anthony John Hutton
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-02-01
Filing date: 2002-02-01
Publication date: 2003-09-03
Also published as: GB0202478D0

Abstract

A solar heating panel has a plurality of parallel aluminium or aluminium alloy extrusions 2, comprising tube centre sections 4 and longitudinal fins 6, which connect together to provide thermal conduction there between. The tubes may have one fin, but preferably have two opposed longitudinal fins 6 extruded therewith. Each fin may engage at its extremity 8,12 with an adjacent fin, wherein one fin edge 8 has a longitudinal open-sided cavity 10 to receive a longitudinal cylinder 14 of the adjacent fin 12. The fins may lie at an angle to each other or may be curved. The tubes are preferably connected to a manifold (24, fig 1), wherein open-sided, longitudinal cylindrical cavities 32, co-extruded with the tubes, receive screws from the manifold. A casing may be provided which is glazed on one side (54, fig 1). There may be a partial vacuum within the casing. Thermal insulation may be provided between the plurality of tubes and the side of the casing opposite the glazed side. The extrusions may be anodised black to aid solar heat absorption. In use, liquid circulates through the tubes.

Description

SOLAR LIQUID HEATING PANEL This invention relates to solar liquid heating panels.

Conventional high quality panels are fabricated from brass tubes with copper fins brazed or soldered between them. Such fabrication requires a high degree of skill and together with the materials is expensive.

Against this background, there is provided a solar liquid heating panel, comprising a plurality of parallel aluminium or aluminium alloy extrusions comprising tubes and fins mterfitting to provide thermal conduction therebetween.

The aluminium required is less expensive than the brass and copper required to make an equivalent conventional panel and the fabrication requires much less skill and is quicker, leading to an all round saving in costs. The tubes and fins would normally be anodised black to aid absorption of radiant energy from the sun.

To save on assembly operations, each tube preferably has at least one longitudinal fin extruded therewith.

Most preferably, each tube has two opposed fins extruded therewith, and each fin engages at its extremity remote from the tube, the extremity of a fin of an adjacent tube to provide said thermal conduction therebetween.

In this arrangement, the extremity of one fin is preferably formed with a longitudinal open sided cavity to receive the extremity of the fin of the adjacent tube. In that form, the open sided cavity is preferably re-entrant and the extremity of the adjacent tube is preferably shaped and dimensioned to be held captive in the cavity.

In order to further aid absorption, the fins preferably lie at an angle to each other in cross section. The enables part of the fins to lie at a better angle to the sun (i. e. so that the sun's rays are nearer normal) towards the beginning and end of the day.

In one form, the fins are curved in cross section.

In a preferred construction, each end of each tube is coupled to a manifold butted to the end of the tube and secured by screws preferably self tapping received by cavities

extruded with the tube. The cavities are preferably open sided longitudinal cylindrical cavities.

In order to decrease heat loss to the surrounding air, the panel preferably includes a casing glazed on une side and there is a partial vacuum within the casing.

One embodiment of the invention will now be described, by way of example with reference to the accompanying drawings, in which : Figure 1 is a cross section through a solar liquid heating panel embodying the invention ; Figure 2 is a cross section through two extrusions used in the panel of Figure 1; Figure 3 is an exploded pictorial view of the panel of Figure 1 ; Figure 4 is a detail pictorial view showing a connection to an extrusion of Figure 2; Figure 5 is a plan view of an array of extrusions contained in the panel of Figure 1, Figure 6 is an end view of an alternative extrusion which may be used in the panel of Figure 1; and Figure 7 is a pictorial view of a short section of the extrusion of Figure 5.

Referring to the drawings, aluminium extrusions 2 have tubular centre sections 4 and opposed longitudinal fins 6. Remote from its tubular section, the extremity 8 of one fin of each extrusion is formed with a longitudinal open sided re-entrant cylindrical cavity 10. Remote from its tubular section, the extremity 12 of the other fin of each extrusion is provided with a longitudinal cylinder 14 so dimensioned as to engage in and be held captive in the cavity 10 of an adjacent extrusion so providing heat conductivity therebetween. Broadly, a dimension (the diameter) of the cylinder is greater than the width of the opening. Adjacent extrusions are assembled into an array 15 (Figure 5) by sliding the cylinder 14 longitudinally into the cavity 10. Surfaces 16 and 18 on respective extremities 8 and 18 abut to constrain the extrusions against rotational or pivotal relative movement. In another form illustrated in Figure 2a, the re-entrant cavity 10 is L-shaped In cross-section. The other fin 6 is L-shaped at its extremity and is dimensioned so as to

be held captive in the L-shaped cavity. Given suitable dimensions in this form it is possible to assemble one fin to another by inserting the L-shaped extremity in the direction of arrow A and rotating in the direction of arrow B.

In use, liquid e. g. water is circulated through the tubes 4 to be heated by radiant energy received by the assembled array 15, to facilitate which, the extrusions are black anodised. The tube is extruded with internal ribs 20 and is subdivided by a web 22. The fins 6 on opposite sides of an extrusion are inclined at an angle to each other. This allows one or the other to be more normal to incident energy from the sun when that IS lower than its zenith.

To circulate the liquid, a manifold 24 is assembled on opposite ends of the tubes.

Each manifold is assembled from a plurality of T-tubes, one for each extrusion 2. The "stem"26 of each T-tube has a flange 28, set at an angle of about 450 to allow accession fixings, for abutment to the end of a tube 4. The joint is sealed with an 0-ring, a die cut gasket, or silicone or, most preferably, polyurethane mastic not shown. The flange IS secured by screws 30 which are received by the ends of respective open sided cylindrical cavities 32 provided in the extrusions 2. The"cross bar"36 of the T-tube is has different diameters at opposite ends. Thus one end 38 has an internal diameter d1 while the other end 40 has an external diameter 01 such that the end 40 of one T-tube fits inside the end 38 of an adjacent T-tube so constructing a manifold for cool inlet liquid on one side and warmer outlet liquid on the other. The T-tubes may be plastic, white to reduce heat loss by radiation, and may be sealed one to another by an adhesive or cement.

The assembled extrusions and manifolds are supported in a casing by an inner frame 44. As may be seen from Figures 1 and 3, two sides of the inner frame are provided with notches 46 each to receive the"stem"26 of a respective T-tube 24. The assembly is held in the inner frame 44 by a back plate 48 over which lies a layer of thermal insulation 50. The casing is completed by an external frame 52 and a glazing

panel 54. The glass has a reflective coating on one side to reflect/trap radiation, e. g.

Pilkinton'K'. End T-tubes extend though holes 56 in the inner frame and complimentary notches 58 and 60 in the backplate 48 and outer frame 52. The glazing panel 54 may be single, double or triple glazed and allows radiant energy to enter the casing where some light will be converted to heat, but reduces heat loss therefrom. Each extrusion has another longitudinal rib 61 which serves multiple functions. It locates the extrusion between opposite sides of the inner frame 44. A shock absorbing longitudinal rubber insert 61 a locates the extrusion against the glazing panel 54. It also helps absorb radiant energy when the sun IS lower than its zenith. The insulation 50 also reduces heat loss and to further reduce heat loss a partial vacuum is drawn in the casing.

The extrusion 62 shown in Figures 6 and 7 is broadly similar to the extrusion 2.

The differences are that the fins 66 are parabolic in cross section and that the tube 64 is flat and has multiple passages 64a therethrough. A similar arrangement of cavities 32 receives screws (not shown) for fixing a flange of a T-tube (not shown), bu the flange and stem of the T-tube are adapted suitably to the flat tube 64.

Each panel is provided with a thermal probe point (not shown) to allow an external sensor circuit to sense a temperature gain with reference to the storage tank and turn on a pump (not shown) to circulate the water through the tubular centre sections 4.

In this case we have shown 10 extrusions but the process allows any multiple or length to be adopted in an array.

Some panels are produced 1 m x 0.5m in the market place but we have shown 1 m x 1 m to simplify any calculations required to match thermal energy requirements to an application. Similarly extrusion length IS only limited by shipping restrictions. It would be possible to use a custom array fashioned to fit a roof e. g. for a new house with glass panel roof.

With longer lengths it may be necessary to peg or pin the interlock at each end as expansion of the alloy may not be even and it would be possible to use a custom array

fashioned to fit a roof e. g. for a new house with glass panel roof would stress the 'T' pipe.

Claims

1 A solar liquid heating panel, comprising a plurality of parallel aluminium or aluminium alloy extrusions comprising tubes and fins interfitting to provide thermal conduction therebetween.

2. A solar panel as claimed in claim 1 wherein each tube has at least one longitudinal fin extruded therewith.

3. A solar panel as claimed in claim 2, wherein each tube has two opposed fins extruded therewith, and each fin engages at its extremity remote from the tube, the extremity of a fin of an adjacent tube to provide said thermal conduction therebetween.

4. A panel as claimed in claim 3, wherein the extremity of one fin is formed with a longitudinal open sided cavity to receive the extremity of the fin of the adjacent tube 5. A panel as claimed in claim 4, wherein the open sided cavity is re-entrant and the extremity of the adjacent tube IS shaped and dimensioned to be held captive in the cavity.

6. A panel as claimed in any of claims 3 to 5, wherein the fins lie at an angle to each other in cross section.

7. A panel as claimed in any of claims 3 to 5, wherein the fins are curved in cross section.

8. A panel as claimed in any preceding claim, wherein each end of each tube is coupled to a manifold butted to the end of the tube and secured by screws received by cavities extruded with the tube.

9. A panel as claimed in claim 8, wherein the cavities are open sided longitudinal cylindrical cavities.

10. A panel as claimed in any preceding claim, including a casing glazed on one side and wherein there IS a partial vacuum within the casing.

12. A panel as claimed in claim 10 or 11 t including thermal insuiation between the plurality of tubes and the side of the casing opposite the glazed side.