GB2075177A - A tubular solar energy absorber - Google Patents

Abstract

The absorber is manufactured from two metallic or plastics strips (3, 4) which are wound off reels (1, 2) continuously and which are seam welded (5, 6) along their edges in order to form a tubular strip (7), the tubular strip being stored on a reel (8). The reel (8) is wound off according to requirements and the strip (7) cut to the required length. The ends of the cut elements are provided with inlet and outlet connections and are closed hermetically be welding. <IMAGE>

Description

SPECIFICATION A tubular absorber for a radiated energy sensor and a method of obtaining semifinished absorber elements of this type This invention relates to radiation absorbers of finned tubular type which convey a heatbearing fluid and which are used in radiated energy, in particular solar, sensors. It relates more particularly to a new absorber of this type and a method for the manufacture of semi-finished elements designed for the construction of such tubular absorbers.

Finned tubular radiation absorbers as used in solar energy sensors are generally constituted by one or a plurality of profiled sheets forming the fins and connected by means of a sequence of seam welds to a tube in which a heat-bearing fluid is designed to flow. Although it is possible to produce absorbers of this type which are satisfactory in terms of efficiency, the manufacturing steps for these are relatively long and therefore relatively expensive, and, as they require component parts which are cut to the final dimensions before welding, they are not suitable for continuous manufacture which would significanty decrease the cost price.

The object of the present invention is to remedy this situation by proposing a tubular radiation absorber of which the fins, in the form of two superposed metal strips welded together along their longitudinal edges, themselves form a casing in which the heat-bearing fluid may circulate, thus eliminating the tube itself, which indispensable in the prior art.

This arrangement permits continuous belt manufacture which, after cutting to the required length, directly provides the semi-finished absorber elements, and the invention proposes a method for obtaining these elements.

The following description of the invention is made with reference to the accompanying drawings, in which: Figure 1 is a very diagrammatic representation of the belt manufacture of the invention Figure 2 is a plan view of a portion of a tubular strip obtained by using the method illustrated in Fig. 1, Figure 3 is a top view of an absorber of the invention obtained from a semi-finished tubular element cut from the above-mentioned strip.

Fig. 1 shows two reels 1 and 2 located one on top of the other about which are wound two metallic strips 3, 4, preferably of metal which is not subject to corrosion, and which are wound off in the direction of the arrows, conveyed and guided in a known manner in such a way as to be superposed and reach a welding station 5 on top of one another, and are introduced into this welding station. Welding may take place in a known way, and preferably, by means of drums 6 supplied by a high frequency electrical generator (not shown) and takes place along continuous paths 9, 10 (Fig. 2) along the edges of the two strips 3, 4 thus ensuring a completely leak-tight longitudinal seal.The two strips 3, 4 jointed in this way along their edges are discharged from the welding station 5 in the form of a single strip 7 which may be immediately wound on a reel 8 of a diameter greater than that of the first two reeis 1, 2 and which performs a storage function.

In the above description the strips 3, 4 are metallic and are joined by longitudinal welds 9, 10. It is however obvious that this continuous, leak-tight join may also be achieved in accordance with known methods by gluing, and that other materials in strips may be used, modern plastics materials offering numerous possibilities.

A continuous surface treatment may be applied to the single strip 7 either before reeling or after reeling by winding off the reel 8. In the latter case, a discontinuous treatment could also be used before possible re-reeling.

According to requirements, the strip 7 is wound off and cut to the required lengths, thus providing the semi-finished tubuar elements in the form of flattened casings which are not sealed at the ends 1 3 (Fig. 3). Connections 11 and 1 2 for the inlet and outlet of the heatbearing fluid are inserted in the vicinity of these ends 1 3 and the ends 1 3 are then hermetically sealed by welding or gluing.

When the completed absorber element is connected to the known collectors and the pressure is exerted by the heat-bearing fluid the upper strip 3 and the lower strip 4 tend to separate from one another elastically between the two paths 9, 10 which join them and the absorber element assumes its final form of an inflated envelope.

When the widths required for the tubular radiation absorbers are relatively low, there is no need in general for any further particular arrangement. However, in some cases very large absorbers are required, which may increase the risks of tearing during inflation.

Therefore, in accordance with a further characteristic feature of the invention, at least one additional weld by means of circular sections 11 (Fig. 2) spaced along a longitudinal axis is performed between the two strips 3, 4 at the continuous welding station 5. This arrangement ensures that the absorber has a good mechanical seal by providing mutually communicating irrigation channels for the heatbearing fluid, and in addition enables the absorber to be fixed to a support, without impairing its leak-tight seal, at right angles to at least one of these weld points.

The considerable economic advantages of the invention provided by the belt manufacture of the semi-finished product are directly obvious from the above description and do not require further details.

Claims (7)

1. A tubular radiation absorber for conveying a heat-bearing fluid for a radiated energy sensor comprising two metallic or plastics material strips which are superposed and joined together in a leak-tight manner along their longitudingal edges to form a tubular housing and joined in the same way at their ends, these being provided respectively with inlet and outlet connections for the heat-bearing fluid.

2. A tubular radiation absorber as claimed in claim 1, characterised in that the two strips are in addition welded to one another at points spaced along at least one longitudinal axis.

3. A method of continuous belt manufacture of part-finished radiation absorber elements for tubular radiation absorbers as claimed in claim 1, comprising the following steps: two reeled strips of material intended to constitute the upper and lower surfaces respectively of absorber elements are unwound in a known manner; the two strips are positioned together and joined to one another by continuous welding or gluing along their edges; and the double strip obtained in this way is then wound onto a storage reel and unwound, in accordance with requirements, for a surface treatment or for cutting of the lengths of elements.

4. A method as claimed in claim 3, characterised in that joining of the edges of the two strips is performed by seam welding.

5. A method as claimed in claim 4, characterised in that the two strips are in addition joined by weld points spaced along at least one longitudinal axis.

6. A tubular radiation absorber substantially as hereinbefore described with reference to the accompanying drawings.

7. A method of continuous belt manufacture of semi-finished radiation absorber elements substantially as hereinbefore described with reference to the accompanying drawings.