ZA200711208B - Solar water heater container - Google Patents

Description

++2007/711208

SOLAR WATER HEATER CONTAINER

FIELD OF THE INVENTION TT

This invention relates to a hot water container for a solar water heater and, more particularly, to a container for a solar water heater using an array of evacuated solar collector tubes as a heat collector. The invention also relates to a solar : 10 water heater embodying such a container.

BACKGROUND TO THE INVENTION

Evacuated tube collectors are known and have a wide range of uses. A tube : 15 collector generally comprises a series of modular tubes (hereinafter referred to as “collector tubes”), mounted in--parallel relationship to each other. Each collector tube comprises a transparent glass tube with an absorber tube contained therein. The absorber and transparent tubes are joined at an end such that there is no fluid communication between the tubes and so that the interior of the absorber tube is open at one end and the space between the absorber and transparent tube is complete sealed off. This space between the ) tubes is evacuated to form a near vacuum and to serve as thermal insulation between the tubes. The tubes are preferably covered with a special light- modulating coating. Sunlight passing through the outer transparent glass tube heats the absorber tube contained within it.

One of the uses of tube collectors, as indicated above, is in solar fluid heaters.

In this application, a tube collector may be fitted to a hot water container in such a manner that the absorber tubes of the collector tubes are in fluid

P1593ZA00 Thirion&Wolmarans communication with the interior of the container and the bodies of the tubes extend from the container. Fluid entering the collector tubes is heated by the sunlight and flows upwards into the container according to the thermosiphon principle.

In an alternative arrangement, the absorber tubes comprise heat transfer mechanism such as heat pipes. The heat transfer mechanisms span the length of the collector tubes, extend into the container and have heat exchangers (condensers) at the ends situated inside the container. In this arrangement, heating of the fluid takes place by means of heat exchange, rather than convection as is the case with thermosiphoning.

In conventional solar fluid heaters operating as described above, the collector tubes enter the container through a series of apertures along the side of the container. Elastomeric seals are used to prevent leakage around the apertures through which the collector tubes have been inserted. These seals, however, suffer the disadvantage that they wear with time. The large temperature fluctuations with which the heater as a whole has to contend places additional strain on the seals due to the expansion and contraction of the materials from which it is manufactured. Worn seals may cause fluid to leak from the tank from between the edges of the apertures and the tubes.

Furthermore, due to the generally rounded shape of the container, conventional elastomeric seals are distorted and do not fit flush with the body of the container around the edges of the apertures. This creates further potential for leakage.

In the remainder of this specification the word “container” should be construed widely so as to include both hot water tanks as well as manifolds that may, in turn, be connected to a hot water tank.

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OBJECT OF THE INVENTION

It is an object of this invention to provide a container for a solar fluid heater ! which will, at least partially, alleviate the abovementioned problems.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a container for a solar fluid heater having a series of communication ports for receiving collector tubes, the container being characterized in that each communication port includes an : aperture providing access to the interior of the container, and a substantially oo rigid retaining sleeve projecting from the container and encircling the aperture.

Further features of the invention provide for each retaining sleeve to be of | generally circular cross-sectional shape; for each communication port to include an inwardly projecting lip on an--inner surface of the retaining sleeve or, alternatively, for each aperture to be of a smaller diameter than the inside diameter of the sleeve in which case the edge of the aperture acts as a lip; and ) for the retaining sleeves to be integral with the container, for example, by the container and retaining sleeves being moulded from fibre reinforced synthetic : resin.

A still further feature of the invention provides for the retaining sleeves to communicate with a surrounding flat section of the wall of the container.

In accordance with a further aspect of the invention there is provided a solar fluid heater assembly comprising a container having a series of communication ports spaced apart along its side, a plurality of evacuated solar collector tubes that are releasably instaled in the communication ports and mounting means for

P1593ZA00 Thirion& Wolmarans mounting the assembly to a structure, the assembly being characterized in that each communication port includes an aperture providing access to the interior of the container, a substantially rigid retaining sleeve projecting from the container and encircling the aperture, and sealing means for preventing leakage between 5 the retaining sleeve and a solar collector tube received therein.

Further features of this aspect of the invention provide for the sealing means to be a resiliently flexible sleeve, alternatively, at least one o-ring; for the container to be of generally cylindrical shape; for the assembly to include an insulating layer and outer housing surrounding the container, and for the insulating layer and housing to be of generally cylindrical shape with a flat mounting surface - positioned to be directed towards a support structure on which the heater assembly is operatively mounted.

In order that the invention may be more fully understood different embodiments thereof will now be described-with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:-

Figure 1 is a sectional side view showing a communication port in the form of a simple aperture in a conventional container for a water heater with a collector tube installed therein and utilising a conventional annular seal, according to the prior art;

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Figure 2 is a sectional side view of a communication port of a container according to the invention with a collector tube installed therein and utilising a sealing sleeve;

Figure 3 is a sectional side view of an alternative embodiment of the communication port of Figure 2 utilising an o-ring as sealing means; and

Figure 4 is an isometric view of a water heating assembly according to the invention.

DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Figure 1 of the drawings illustrates a communication port in the form of a simple aperture (1) in the wall of a conventional solar water heater container (3) according to the prior art. The aperture operatively receives an end region of an. evacuated solar collector tube (5), of the type commonly used in solar water heaters.

To prevent leakage at the edge of the aperture (1) that has a collector tube (5) installed therein, an annular elastomeric seal (9) is used, as illustrated. The seal (9) has two annular flanges (11) forming a groove (13) between them and is installed in the aperture (1) so that the edge (17) defining the aperture (1) is received in the groove (13), between the flanges (11). When a collector tube (5) is installed in the aperture (1), the inner radius (7) of the seal (9) locates against the outer transparent tube (15) of the collector tube (5) so as to prevent leakage from between the edge (17) and the tube (5).

P1593ZA00 Thirion& Wolmarans

Due to the cylindrical shape of the body of the container (3), the seal (9) is forced to adopt a convex shape in conformity with the body of the container.

This prevents at least the outer flange (19) of the seal (9) from being flush with the edge (17). The distortion of the seal (9) can reduce its sealing ability and it should be appreciated that leakage of the water in the container (3) could result.

Turning now to the embodiment of the invention that is illustrated in Figures 2 and 4 of the drawings, the container (21) has a series of communication ports (23) spaced apart along its wall (25).

Each communication port (23) has an aperture (27) and a rigid retaining sleeve (29) projecting from the container (21) and encircling the aperture (27). The diameter of the aperture (27) is smaller than the inner diameter of the retaining sleeve (29) and thus forms an inwardly projecting lip (31) extending from the inner edge of the retaining sleeve (29). The lip (31) acts as a stop for the collector tube (32).

In use, a collector tube (32) is releasably installed in each of the communication ports (23). An open end (33) of the tube (32) is slid into the retaining sleeve (29) until the end (33) of the tube (32) is positioned close to, but not against, the lip (31). A resiliently flexible sealing sleeve (35) is installed partially over the outer surface of the retaining sleeve (29) and partially over the tube (32). It should be appreciated that the sealing sleeve (35) is stretched to act as a seal to prevent water leaking from the container (21) between the edges of the retaining sleeve (29) and the collector tube (32).

Once the collector tubes (32) have been installed in all the communication ports (23), the interior of the absorber tubes (37) of all the collector tubes (32) are in fluid flow communication with the interior of the container (21). Water flowing

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into the absorber tubes (37) will therefore be warmed by solar energy and the remainder of the water in the container (21) will be warmed by convection.

The container (21) and retaining sleeves (29) can be integrally moulded from a fibre reinforced synthetic resin but may also be manufactured by fabrication from any other suitable material, for example, a metal such as copper.

The sealing sleeve (35) in turn may be manufactured from an elastomeric material with suitable sealing characteristics such as a silicon rubber. :

Figure 4 of the drawings illustrates a solar water heating assembly (30) having a number of collector tubes (32). For illustrative purposes, the first three tubes (32) are shown with sealing sleeves (35) in place, while the remainder of the tubes and sleeves are shown without them.

An alternative embodiment of the invention is illustrated in Figure 3 of the drawings. In this embodiment the sealing sleeve (35) of Figures 2 and 4 is replaced with an O-ring (39). The O-ring (39) is positioned inside a shallow groove on the inner surface of the retaining sleeve (29) and projects radially past the edge of the groove to engage the outer surface of the collector tube (32). It should, however, be appreciated that any alternative sealing means may be . used and that the invention is not limited to those described.

Solar water heaters are often mounted on the roofs of buildings and as a result are subjected to harsh weather conditions. For example, a solar water heater may be subjected to extreme heat and direct sunlight in summer and extreme cold in winter. In addition, the same water heater may be subjected to large ’ internal temperature changes in a relatively short period of time. In conventional solar water heaters of the type described, the components and, more ] P1593ZA00 Thirion& Wolmarans particularly, the water in the container expands and contracts as temperatures change.

This expansion and contraction creates longitudinal forces along the collector tubes (5) which translates into shearing forces on the prior art seal (9) as illustrated in Figure 1 of the drawings. These shearing forces can cause the prior art seal (9) to wear faster.

In the embodiments of the invention illustrated in Figures 2 to 4 of the drawings, the sealing sleeve (35) or o-ring (39), as the case may be, are more readily capable of absorbing the shearing forces than the seal (9) that is illustrated in

Figure 1 of the drawings.

It is furthermore known that a rapid decrease in temperature in the container (21) may cause the pressure in the container (21) to drop substantially. This decrease in pressure may cause-the collector tubes (32) to be sucked into the container (21) which may cause substantial damage to the collector tubes (32).

It should therefore be appreciated that in the embodiment of the invention illustrated in Figures 2 to 4 of the drawings, the inwardly projecting lip (31) prevents the collector tubes (32) from being sucked into the container (21).

In use, the container (21) is enclosed in an insulating layer contained within an outer housing which, as illustrated in Figure 4 of the drawings. As provided by this invention the outer housing has a flattened mounting surface (41) to facilitate affixing it to the surface of a structure such as a roof and to provide a bit configuration for mounting close proximity to a roof. Attachment means (43) are furthermore provided to fasten the assembly to the structure.

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A bracket (45) can optionally be included towards the lower ends of the tubes (32) to prevent movement of the tubes (32) relative to one another. Such relative movement may case damage to the tubes (32) at the communication ports (23). The bracket (45) may also include means for securing the lower end : regions of the tubes to the structure.

The invention therefore provides a solar heater container which may be employed to solve a number of problems associated with conventional containers.

The above description is, however, by way of example only and should not be considered as limiting on the scope of the invention. Numerous alterations may be made to the invention described without departing from the scope hereof.

P1593ZA00 Thirion& Wolmarans

Claims (12)

‘ ' ry / ~ CLAIMS: NE

1. A container for a solar fluid heater having a series of communication ports for receiving collector tubes, the container being characterized in that each communication port includes an aperture providing access to the : interior of the container, and a substantially rigid retaining sleeve projecting from the container and encircling the aperture.

2. A container as claimed in claim 1 in which each retaining sleeve is of generally circular cross-sectional shape. :

3. A container as claimed in either one of claims 1 or 2 in which each communication port includes an inwardly projecting lip on an inner surface of the retaining sleeve.

4. A container as claimed in-either one of claims 1 or 2 in which each aperture is of a smaller diameter than the inside diameter of the sleeve in which case the edge of the aperture acts as a lip.

5. A container as claimed in any one of the preceding claims in which the retaining sleeves are integral with the container.

6. A container as claimed in claim 5 in which the container and retaining : sleeves are moulded from fibre reinforced synthetic resin.

7. A container as claimed in any one of the preceding claims in which the retaining sleeves communicate with a surrounding flat section of the wall of the container. P1593ZA00 Thirion& Wolmarans

8. A container substantially as herein described and exemplified with reference to either one of Figures 2 and 3 of the accompanying drawings.

9. A solar fluid heater assembly comprising a container having a series of communication ports spaced apart along its wall, a plurality of evacuated solar collector tubes that are releasably installed in the communication ports, and mounting means for mounting the assembly to a structure, the assembly being characterized in that each communication port includes an aperture providing access to the interior of the container, a substantially rigid retaining sleeve projecting from the container and - encircling the aperture, and sealing means for preventing leakage between the retaining sleeve and a solar collector tube received therein.

10. A solar fluid heater assembly as claimed in claim 9 in which the sealing means are selected from a resiliently flexible sleeve engaging the outer surface of the sleeve and-collector tube and at least one o-ring sealing between the inner surface of the sleeve and collector tube.

11. A solar fluid heater assembly as claimed in either one of claims 9 or 10 in which the container is of generally cylindrical shape and includes an insulating layer and outer housing surrounding the container wherein the housing is of generally cylindrical shape with a flat mounting surface : positioned to be directed towards a support structure on which the heater assembly is operatively mounted.

12. A solar fluid heater assembly substantially as. herein described and exemplified with reference to Figure 4 of the accompanying drawings. P1593ZA00 Thirion& Wolmarans

Dated this 18" day of December 2007 ROWAN JOSEPH for the applicant N

P1593ZA00 Thirion& Wolmarans