Solar Collector

The present invention relates to a solar collector for converting solar radiation into heat and to transfer the latter with the maximum possible efficiency to a fluid heat transferring means (e.g. water or air) whereby the heat can be utilised in a domestic or industrial application, for example to heat a domestic hot water or central heating system.

A solar collector typically comprises a number of heat pipes, the essential function of which is to transfer and to distribute heat by vaporization and condensation of a working fluid (heat-transfer medium). The principal feature of these is that the energy which is required for the flow of the liquid and the vapour in the presence of the gravity pull and in relationship with the losses due to sliding friction is completely provided by the heat source, so that no external pumping source is necessary. A known solar collector is disclosed in GB2103350.

Each heat pipe of the solar collector typically comprise a radiation adsorbing plate for absorbing solar radiation and an elongate tube containing a heat transfer medium having an evaporator section, in thermal contact with said radiation adsorbing plate, and a condenser section remote from said plate, said plate and said evaporator section of said elongate tube being enclosed within an evacuated radiation transparent enclosure to prevent heat loss.

The solar collector further comprises a heat collection manifold containing a fluid to be heated and having at least one heat tube receiving aperture therein for insertion of said condenser section of the elongate tube to permit heat transfer between the heat transfer medium within the condenser section of the elongate tube and the fluid contained within the heat collection manifold.

Two means are generally applied to connect the evacuated heat pipes to the manifold. In one case the condenser is immersed in the heat transfer fluid of the manifold, i.e. the tube is connected in a wet environment. A multiple part seal arrangement typically forms the seal between the tube and the manifold.

One of the problems with known seal systems is that they include multiple parts and are difficult and time consuming to assemble and install. In addition, to date known systems rely on rigid connections between the heat pipes and the manifold, which under certain circumstances could lead to failure of the assembly due to mechanical failure.

The main object of the present invention is to provide a solar collector having a high efficiency and which can be constructed cheaply, and can readily be assembled and overhauled and which will address at least some of the problems outlined above.

Statements of Invention

According to the present invention there is provided a solar collector comprising at least one heat pipe, said at least one heat pipe comprising a radiation adsorbing plate, an elongate tube containing a heat transfer medium having a first section, defining an evaporator section, in thermal contact with said radiation adsorbing plate, and a second section, defining a condenser section, said plate and said first section of said elongate tube being enclosed within an evacuated radiation transparent enclosure, and a heat collection manifold containing a fluid to be heated and having at least one heat pipe receiving aperture therein for insertion of said second section of the elongate tube to permit heat transfer between the heat transfer medium within the condenser section of the elongate tube and the fluid contained within the heat collection manifold, wherein a sealing means is provided around the elongate tube between the first and second sections, the sealing means comprising:-

an inner seal to form a fluid tight seal around a section of the elongate tube between the first and second sections of the elongate tube; and an outer seal to form a fluid tight seal against an inner circumferential surface of said heat pipe receiving aperture.

In a preferred embodiment the sealing means comprises an elastomeric plug provided on the elongate tube having a central aperture with an inner surface to form a circumferential seal around a section of the elongate tube between said first and second sections, and an outer surface to form a fluid tight seal against an inner circumferential surface of said heat pipe receiving aperture.

One or more circumferential projections or barbs may be provided on the outer surface of the plug to provide an enhanced seal against the inner circumferential surface of the heat pipe receiving aperture and/or to resist removal of the heat pipe from the aperture.

Preferably said central aperture of said plug is located over a smooth region of the elongate tube between said second section and said flexible region. One or more circumferential projections or barbs may be provided on the inner surface of the plug to provide an enhanced seal against the smooth region of the elongate tube.

Preferably said elongate tube includes a flexible region between said first and second sections to provide a flexible interface between the tube and the manifold. The flexible region may comprise a corrugated or convoluted section of said elongate tube.

A retaining washer may be provided, preferably located in one of the flexible bellow convolutions, to hold the plug in position.

A securing means, such as a resilient clip, may be incorporated with the said heat pipe receiving aperture, once the second section of the elongate tube along with the sealing means has been inserted therein, to resist removal of the heat pipe from the manifold.

Brief Description of the Drawings

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:-

Fig. 1 is a perspective view of a solar collector;

Fig. 2 is a sectional view through a heat pipe of the solar collector of Fig. l;

Fig. 3 is a sectional close-up perspective view of the manifold of the solar collector of Fig. 1 illustrating the condenser sealing section of a solar tube;

Fig. 4 is a perspective view of the assembled condenser sealing section;

Fig. 5 is a plan view of the assembled condenser sealing section;

Fig. 6 is an exploded view of the assembled condenser sealing section of Figs. 4 and 5 illustrating the constituent components of the condenser and the sealing section ;

Fig.7 is an exploded plan view of the sealing section of Fig.6;

Fig. 8 is a cross sectional view of the assembly of the seal and flexible section inserted into the manifold chamber aperture and illustrates the axial forces acting upon the seal in both the internal and external axial planes; and

Fig. 9 is a cross sectional view illustrating the insertion of the condenser and seal assembly into the manifold chamber aperture with a retaining clip in place.

Detailed Description

As illustrated in the drawings, a solar collector 1 comprises a plurality of heat pipes 2 arranged in parallel on a support rail assembly 3 and inserted into a manifold 4 via a plurality of manifold apertures 10. Each heat pipe comprises an evaporator section 5, comprising a radiation adsorbing plate 6 for absorbing solar radiation and a portion of an elongate tube 7, containing a heat transfer medium, in thermal contact with said radiation adsorbing plate 6, and a condenser section 9. The evaporator section 5 is enclosed within an evacuated radiation transparent enclosure 8 to prevent heat loss.

Each heat pipe includes a condenser section 9 at a distal end of the elongate tube 7 remote from the evaporator section 5, wherein the vaporised heat transfer medium evaporated in the evaporator section 5 is condensed before draining back down into the evaporator section 5.

The condenser section 9 of each heat pipe 2 is inserted into a manifold chamber 16 via chamber apertures 17, whereby heat transfer can take place between the condenser sections 9 of the heat pipes 2 and the heat transfer fluid (e.g. water) contained within the manifold chamber 16. The manifold chamber 16 includes

inlet and outlet pipes 12, 13 to allow the heat transfer fluid in the manifold chamber 16 to be circulated through a heating system.

In order to avoid damage to the heat pipes 2 and manifold chamber 16 during assembly due to misalignment and when in use due to impact or movement, a region of the elongate tube 7 of each heat pipe 2 between the evaporator 5 and condenser 9 is formed as a flexible section 14 in the form of a convoluted or corrugated section of tube 14".

In use, the condenser sections 9 of the heat pipes 2 are immersed within the fluid contained within the manifold chamber 16. In the invention, a seal is provided between the heat pipes 2 and the chamber apertures 17, allowing the wet connection of the evacuated heat pipe tubes 2 to the manifold chamber 16.

In a preferred embodiment, the seal comprises an elastomeric plug 15 dimensioned to fit tightly within the chamber aperture 17 and having a central aperture 18 within which the elongate tube 7 of the heat pipe 2 is a fluid-tight fit to allow fast and reliable tube to manifold installations. Preferably said elastomeric plug 15 is located on a smooth section 14" of the flexible section 14 located adjacent to the elongate tube 7.

The seal of the invention readily seals against the smooth section 14'" of the flexible section 14 without any additional parts. This is preferably achieved as illustrated in Figs. 8 and 9 in particular by providing the seal as an elastomeric plug 15 sealing between a smooth region 14" of the flexible section 14 and the inner surfaces of the chamber aperture 17 while accommodating for a large change in diameter between the flexible section 14 and the chamber aperture 17.

The plug seal facilitates the fast and reliable installation of the heat pipe tube.

In this case the elastomeric plug 15 is provided with circumferential ridges or barbs 22 provided on the outer surface of the elastomeric plug 15 which provide a high pressure resistant fluid-tight seal against the inner circumferential surface of the chamber apertures 17. The elastomeric plug 15 is also provided with circumferential ridges or barbs 20 on the inner surface of the elastomeric plug 15 which provide a high pressure resistant fluid-tight seal against the outer circumferential surface of a smooth section 14" of the flexible section 14.

A locking plate 21 such as, but not exclusively, a metal disk may be located in one of the convolutions 14' of the flexible section 14. The locking plate 21 may be secured in position with, but not exclusively, a resilient circlip 19 that locates in one of the convolutions 14' of the flexible section 14. The locking plate 21 and the circlip 19 serve to secure the elastomeric plug 15 in position and maintain an intimate contact of the chamfered edge 25 of the elastomeric plug 15 with the condenser 9 even under high pressure and temperature.

In addition the locking plate 21 compresses the elastomeric plug 15 to circumferentially constrict the central aperture 18 and to compress the inner circumferential ridges or barbs 20 against the smooth surface 14" of the flexible section 14.

In one embodiment of the present invention the chamber aperture 17 is provided with a slot 23 to allow the insertion of a resilient clip 24 into said slot the function of which is to engage with the locking plate 21 to secure the heat pipe 2 in place within the manifold chamber 16 even under high pressure and temperature.

Upon insertion of the condenser 9 into the chamber aperture 17 the design of the elastomeric plug 15 is such that it is compressed further to enhance the circumferential sealing in an internal axial compression 26 of the circumferential ridges or barbs 20 against the smooth surface 14" of the flexible section 14.

Additionally the flexible section 14 resists such an internal axial compression 26 such that an external axial compression force 27 is applied against the inner circumferential surface of the chamber aperture 17.

In the invention, the separate heat pipes and the manifold of the solar collector are capable of being readily assembled on site whilst being capable of taking up the tolerances required without risk of damage or leakages. In addition, the component parts are easily replaceable.

Various modifications and variations to the described embodiments of the inventions will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments.