GB1587511A

GB1587511A - Solar radiation heating apparatus

Info

Publication number: GB1587511A
Application number: GB42835/75A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-01-14
Filing date: 1977-01-14
Publication date: 1981-04-08

Description

(54) SOLAR RADIATION HEATING APPARATUS (71) I, AYNSLEY MAXWELL BROWN, a British subject of 18 Weston Road, Churchtown, Dublin 14, Republic of Ireland (formerly of 58 Beverley Drive, Edgware, Middlesex HA8 5NG), do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to solar radiation heating apparatus and, more particularly, to solar radiation heating apparatus and methods of heating fluid by solar radiation.

Heretofor, the development of solar radiation heating apparatus has been directed primarily to providing apparatus for use in countries where solar radiation is plentiful and long periods of uninterrupted sunshine are common. While such apparatus seems to function satisfactorily in these countries, it has been found that in many cases the apparatus will not operate satisfactorily during the daylight hours.

One object of the present invention is to provide an improved and relatively inexpensive solar radiation heating apparatus.

According to one aspect of the present invention there is provided a solar radiation heating apparatus comprising a thin-walled element supported in an inclined position with respect to the horizontal so as to enable the element to intercept solar radiation on one surface thereof, means for supplying to the said element fluid to be heated by the intercepted solar radiation, and means for collecting heated fluid, the said fluid supply means being arranged to supply fluid to be heated to the other surface of the said element, such that the supplied fluid attaches to the said other surface in a layer or film under the constraint of the Coanda effect, and flows to the said fluid collection means.

The heating apparatus may include means to assist the supplied fluid to attain and maintain an even layer of film during its passage over the said other surface of the element.

In such a case, the said element may have a multiplicity of shallow grooves formed in its said other surface, the grooves extending substantially in the direction of intended fluid flow.

The said element may be of planar form.

Alternatively, the said element may be of tubular or arcuate shape in cross-section.

The said fluid supply means may comprise a tubular member. In these circumstances, the tubular member may have a multiplicity of apertures formed therein at spaced locations along its length through which the fluid is to be supplied to the said element.

The heating apparatus may include means for permitting operation of the said fluid supply means only when the temperature of the intercepted solar radiation is at least in excess of the temperature of the said fluid.

The fluid may be suitably treated to minimise any adverse effect on the apparatus caused by corrosion, algae growth or other accumulations.

According to another aspect of the present invention there is provided a method of heating fluid by solar radiation comprising disposing a thin-walled element in an inclined position with respect to the horizontal to intercept solar radiation on one surface thereof, supplying fluid to be heated to the other surface of the said element, such that the supplied fluid attaches to the said other surface in a layer or film under the constraint of the Coanda effect and flows to the said fluid collection means.

Various forms of solar radiation heating apparatus in accordance with the present invention will now be described, by way of example, with reference to the accompanying drawings in which Figure 1 is an isometric view, partly in section, of a first form of solar radiation heating apparatus; Figure 2 is an isometric view showing a radiation interceptor panel and heat exchanger of the apparatus of Figure 1; Figure 3 is a sectional end view of the part of the apparatus shown in Figure 1; Figure 4 is an isometric view of another form of solar radiation heating apparatus.

Referring to Figures 1 to 3 of the drawings, the heating apparatus includes a rectangular panel 10 to absorb solar radiation. Conveniently the panel 10 is a metal sheet approximately 2 mm thick of, for example, galvanised steel or aluminium. Alternatively the panel 10 may be of plastics. The panel 10 is suitably treated on one surface, the upper surface in Figure 1, to absorb solar radiation, and is provided on its other surface with a plurality of fine grooves that extend parallel to the longer edges of the panel.

The panel 10 is mounted on a shallow tray 11 secured to the lower surface of the panel, by, for example, welding along the edges of the rectangular panel, the base of the tray 11 being spaced from the grooved surface of the panel 10 so as to permit the fluid to be heated, a liquid, to flow in a layer or film over that surface. This liquid is supplied through a tube 12 formed in the tray 11 extending parallel to, and disposed adjacent to, the upper edge (Figure 2) of the panel 10, the tube 12 is coupled to a liquid inlet nozzle 13 and the tray 11 is provided with a series ofjets constituted by apertures in the tube 12, spaced apart along the length of the tube 12, which permit the liquid to be delivered to the grooved surface of the panel 10 in the form of a fine spray.

Adjacent the lower edge of the panel 10 the tray 11 has a liquid collection trough 14 which communicates with an outlet nozzle 15.

The composite assembly of the panel 10 and tray 11 is mounted in a shallow box-like container 16 whose top is provided by a glass sheet 17. The panel 10 is disposed adjacent the glass sheet 17 and a layer 18 of heat insulation material is provided between the tray 11 and the base of the container 16. Conveniently the external surface of the container 16 is glazed to improve its weather-resistant properties. The container 16 is provided with anchorages (not shown) to facilitate appropriate mounting of the heating apparatus in relation to the sun's apparent diurnal movement.

In use, the container 16 is mounted in an inclined position by support means (not shown) so that the glass sheet 17 faces South to permit solar radiation to be intercepted and absorbed on the exposed surface of the panel 10, to heat the panel, and the panel is inclined at the desired angle to the horizontal. The temperature of the panel 10 is sensed by a suitable sensor (not shown) and whenever this temperature exceeds the temperature of the liquid to be heated, a pump in the liquid supply circuit is energised to supply liquid via the hole 12 to the grooved surface of the panel. This liquid flows down the grooved surface of the panel 10 under the influence of gravity and under the constraint of the Coanda effect to be heated by the panel.

It has been found that by utilising the Coanda effect the liquid may be caused to flow over the grooved surface relatively slowly and in a thin film and thereby provide for satisfactory operation of the heating apparatus even in countries where the solar radiation varies considerably.

The grooves on the panel 10 spread the liquid so as to cause the liquid to flow over substantially the whole of this surface and thereby improve the efficiency of the heating apparatus. In an alternative arrangement this is achieved by coating the surface of the panel 10 with a wetting agent.

It is intended that the panel 10 be disposed so as to absorb solar radiation when it is normally most plentiful. However, it is visualised that with our capricious and variable weather pattem the periods during which solar radiation is most plentiful may vary considerably from day-to-day. This difficulty may be overcome by providing a mechanism to adjust the angular position of the panel 10 so that it is always in the required angular position to absorb the available solar radiation. However, it is visualised that this driving mechanism would add considerably to the cost of the heating apparatus and thereby defeat one of the main advantages of the heating apparatus.

In order to overcome this difficulty the solar radiation heating apparatus may be of the kind shown in Figure 4. Referring to Figure 4, the heating apparatus includes a tubular glass cover 22 and a tubular heat absorber 23, for absorbing solar radiation, coaxially mounted in the cover 22. This tube 23 may be of metal, plastics or glass. The heating apparatus is mounted in an inclined position so that its longitudinal axis extends normally to the sun's average declination and the tubular heat absorber 23 will thus always absorb any available solar radiation. The fluid to be heated, a liquid, is delivered through a tube 24 extending longitudinally through the absorber 23 and mounted in end walls 25 of the absorber. The tube 24 may be axially mounted on the tube 23.The tube 24 has apertures formed therein at spaced locations along its length through which the liquid is delivered in the form of a fine spray to the inner surface of the tubular absorber 23. This liquid flows down the inner surface of the absorber 23 where it is collected and delivered through an outlet tube 26 carried by the absorber 23.

The liquid to be heated is delivered to the tube 24 by a pump, the apparatus including a sensor (not shown) for sensing the temperature of the solar radiation or the absorber 23, and permitting operation of the pump only when the sensed temperature exceeds the temperature of the liquid.

The inner surface of the absorber 23 may be grooved in the direction of intended liquid flow.

Various modifications may be made to the embodiments described without exceeding the scope as defined in the appended claims. For example, the tubular absorber 23 may be replaced by an absorber that is of arcuate crosssection. Also the grooves in the panel 10 of Figures 1 to 3 may be provided by ribs secured to the panel. The panel 10 and the tube 23 may be of a kind that are merely capable of intercepting rather than absorbing solar radiation.

WHAT I CLAIM IS: 1. A solar radiation heating apparatus comprising a thin-walled element supported in an inclined position with respect to the horizontal so as to enable the element to intercept solar radiation on one surface thereof, means for

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Claims

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edges of the panel.

The panel 10 is mounted on a shallow tray 11 secured to the lower surface of the panel, by, for example, welding along the edges of the rectangular panel, the base of the tray 11 being spaced from the grooved surface of the panel 10 so as to permit the fluid to be heated, a liquid, to flow in a layer or film over that surface. This liquid is supplied through a tube 12 formed in the tray 11 extending parallel to, and disposed adjacent to, the upper edge (Figure 2) of the panel 10, the tube 12 is coupled to a liquid inlet nozzle 13 and the tray

11 is provided with a series ofjets constituted by apertures in the tube 12, spaced apart along the length of the tube 12, which permit the liquid to be delivered to the grooved surface of the panel 10 in the form of a fine spray.

Adjacent the lower edge of the panel 10 the tray 11 has a liquid collection trough 14 which communicates with an outlet nozzle 15.

The composite assembly of the panel 10 and tray 11 is mounted in a shallow box-like container 16 whose top is provided by a glass sheet 17. The panel 10 is disposed adjacent the glass sheet 17 and a layer 18 of heat insulation material is provided between the tray 11 and the base of the container 16. Conveniently the external surface of the container 16 is glazed to improve its weather-resistant properties. The container 16 is provided with anchorages (not shown) to facilitate appropriate mounting of the heating apparatus in relation to the sun's apparent diurnal movement.

In use, the container 16 is mounted in an inclined position by support means (not shown) so that the glass sheet 17 faces South to permit solar radiation to be intercepted and absorbed on the exposed surface of the panel 10, to heat the panel, and the panel is inclined at the desired angle to the horizontal. The temperature of the panel 10 is sensed by a suitable sensor (not shown) and whenever this temperature exceeds the temperature of the liquid to be heated, a pump in the liquid supply circuit is energised to supply liquid via the hole 12 to the grooved surface of the panel. This liquid flows down the grooved surface of the panel 10 under the influence of gravity and under the constraint of the Coanda effect to be heated by the panel.

It has been found that by utilising the Coanda effect the liquid may be caused to flow over the grooved surface relatively slowly and in a thin film and thereby provide for satisfactory operation of the heating apparatus even in countries where the solar radiation varies considerably.

The grooves on the panel 10 spread the liquid so as to cause the liquid to flow over substantially the whole of this surface and thereby improve the efficiency of the heating apparatus. In an alternative arrangement this is achieved by coating the surface of the panel 10 with a wetting agent.

It is intended that the panel 10 be disposed so as to absorb solar radiation when it is normally most plentiful. However, it is visualised that with our capricious and variable weather pattem the periods during which solar radiation is most plentiful may vary considerably from day-to-day. This difficulty may be overcome by providing a mechanism to adjust the angular position of the panel 10 so that it is always in the required angular position to absorb the available solar radiation. However, it is visualised that this driving mechanism would add considerably to the cost of the heating apparatus and thereby defeat one of the main advantages of the heating apparatus.

In order to overcome this difficulty the solar radiation heating apparatus may be of the kind shown in Figure 4. Referring to Figure 4, the heating apparatus includes a tubular glass cover 22 and a tubular heat absorber 23, for absorbing solar radiation, coaxially mounted in the cover 22. This tube 23 may be of metal, plastics or glass. The heating apparatus is mounted in an inclined position so that its longitudinal axis extends normally to the sun's average declination and the tubular heat absorber 23 will thus always absorb any available solar radiation. The fluid to be heated, a liquid, is delivered through a tube 24 extending longitudinally through the absorber 23 and mounted in end walls 25 of the absorber. The tube 24 may be axially mounted on the tube 23.The tube 24 has apertures formed therein at spaced locations along its length through which the liquid is delivered in the form of a fine spray to the inner surface of the tubular absorber 23. This liquid flows down the inner surface of the absorber 23 where it is collected and delivered through an outlet tube 26 carried by the absorber 23.

The liquid to be heated is delivered to the tube 24 by a pump, the apparatus including a sensor (not shown) for sensing the temperature of the solar radiation or the absorber 23, and permitting operation of the pump only when the sensed temperature exceeds the temperature of the liquid.

The inner surface of the absorber 23 may be grooved in the direction of intended liquid flow.

Various modifications may be made to the embodiments described without exceeding the scope as defined in the appended claims. For example, the tubular absorber 23 may be replaced by an absorber that is of arcuate crosssection. Also the grooves in the panel 10 of Figures 1 to 3 may be provided by ribs secured to the panel. The panel 10 and the tube 23 may be of a kind that are merely capable of intercepting rather than absorbing solar radiation.

WHAT I CLAIM IS: 1. A solar radiation heating apparatus comprising a thin-walled element supported in an inclined position with respect to the horizontal so as to enable the element to intercept solar radiation on one surface thereof, means for

supplying to the said element fluid to be heated by the intercepted solar radiation, and means for collecting heated fluid, the said fluid supply means being arrange to supply fluid to be heated to the other surface of the said element, such that the supplied fluid attaches to the said other surface in a layer or film under the constraint of the Coanda effect and flows to the said fluid collection means.
2. A heating apparatus according to Claim 1, including means to assist the supplied fluid to attain and maintain an even layer or film during its passage over the said other surface of the element.
3. A heating apparatus according to Claim 1 or Claim 2, wherein the said element has a multiplicity of shallow grooves formed in its said other surface, the grooves extending substantially in the direction of intended fluid flow.
4. A heating apparatus according to any one of the preceding claims, wherein the said element is of planar form.
5. A heating apparatus according to Claims 1 to 3 wherein the element is of tubular or arcuate shape in cross-section.
6. A heating apparatus according to any one of the preceding claims, wherein the said fluid supply means comprises a tubular member.
7. A heating apparatus according to Claim 6, wherein the said tubular member has a multiplicity of apertures formed therein at spaced locations along its length through which the fluid is to be supplied to the said element.
8. A heating apparatus according to Claim 4 and Claim 6 or Claim 7, wherein the said tubular member is disposed adjacent the upper end of the said planar element and extends substantially transversely thereof.
9. A heating apparatus according to Claim 5 and Claim 6 or Claim 7, wherein the said tubular member extends longitudinally of the tubular or arcuate element.
10. A heating apparatus according to any one of the preceding claims, including means for permitting operation of the said fluid supply means only when the temperature of the intercepted solar radiation is at least in excess of the temperature of the said fluid.
11. A solar radiation heating apparatus substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.
12. A solar radiation heating apparatus substantially as hereinbefore described with reference to Figure 4 ofthe accompanying drawings.
13. A method of heating fluid by solar radiation comprising disposing a thin-walled element in an inclined position with respect to the horizontal to intercept solar radiation on one surface thereof, supplying fluid to be heated to the other surface of the said element, such that the supplied fluid attaches to the said other surface in a layer or film under the constraint of the Coanda effect, and flows to the said fluid collection means.