DE2849585A1 - SOLAR COLLECTOR AND ITS PRODUCTION - Google Patents

Description

ELF UNION, Paris, France

Solar collector and its manufacture

The invention relates to a falling film solar collector which can be stored ready for use in roll form and after appropriate cutting to the dimensions of any, preferably insulating carrier mounted on these can also be a process for the production of these collectors and their use for heating swimming pools as well as for hot water preparation, for example for heating domestic water.

In the FR patent application 76-353 ^ 5 of November 24, 1976 is a falling film collector specified, which essentially consists of a planar support with a fiber mat located on it, which may be used to achieve the so-called greenhouse effect is provided with a transparent cover. The carrier is preferably insulating, oriented to the south and arranged at a suitable incline. This collector is

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furthermore by a distribution device for the heat transfer fluid characterized, which has a liquid accumulation at its entrance into which the upper end of the fiber mat is immersed, whereby an automatic impregnation as well as a homogeneous flow down due to the force of gravity through the fiber mat are guaranteed.

If a transparent cover, for example made of glass or a plastic film, is provided, a frame is used for holding it this cover and sealing devices are required.

The falling film solar collector according to the invention is based on a new and very economical concept and is therefore characterized in that the transparent cover of corresponding previous collectors is replaced by a transparent plastic film which is applied directly to the surface of the fiber mat and connected to it in a suitable manner is, for example by spraying on or spraying with a spray gun, gluing or gluing, welding or about by glaze-like treatment or partial melting of the fiber mat surface.

The plastic film produced in this way prevents the evaporation of the heat transfer fluid such as water and results in an only slightly reduced greenhouse effect compared to frame-mounted transparent covers.

According to the invention, the fiber mat serves as a carrier for the transparent cover, which creates a separate transparent cover Cover made of glass or plastic, seals as well as a Support frames for this cover are omitted; the fiber mat can in turn be provided on a tight support, the at the edges with the transparent film or the transparent

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th film is welded, for example, and thus represents a kind of "solar mat".

This novel technical concept is particularly advantageous when very favorable influencing variables such as strong solar radiation, high outside temperature and a need for ^{service water in the temperature range from 20 to kO 0} C are present at the same time.

This is the case, for example, in outdoor swimming pools or in the production of process water for sanitary purposes in summer holiday resorts. For such purposes, any properly inclined and aligned surface located in the vicinity of the place of use can be used as a carrier for the fiber mat, for example the roofing of technically used rooms or adjacent structures, embankments, the floor, slightly inclined concrete or tiled surfaces, roofs of the stands of stadiums, etc.

The production of the transparent film, which directly covers the surface of the fiber mat, can be in various ways V / can be done.

The invention is illustrated below with the aid of exemplary embodiments, the details of which are not restrictive and are explained in more detail in the drawing; show it:

Fig. 1 is a cross-sectional view through a first embodiment of the invention Falling film collector;

Figure 2 is a cross-sectional view of a second

Embodiment of the falling film collector;

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Pig. 3 shows the assembly of the collector according to the invention on a carrier;

Fig. 4 shows another way of attaching the invention Collector;

Fig. 5 is a general diagram of a coextrusion device;

6 shows a manifold;

7 shows a right-angled cross-section through a
with the assembled collector
Bonding or welding connected manifold;

Fig. 8 is a right-angled cross-section through a
profiled obtained by extrusion
Manifold

and

9 shows a device for producing the side welds of the collectors according to the invention.

In the case of the first according to the invention shown in FIG. 1 The embodiment is on the upper side that on the carrier 3 provided fiber mat 1, a film 2 of a thermoplastic resin serving as a closure is provided, the absorption spectrum of which so is that the maximum usable solar energy is let through while the layer is in the far infrared

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is opaque.

The film is applied in situ in a manner known per se, for example with a spray gun, a coating roller, by spatula and the like.

In the second embodiment of the invention shown in Fig. 2, a transparent film 2 is on the surface the fiber mat 1 is provided by gluing, welding or any other, with the type of fibers and the Films 2 is connected to it in a compatible, suitable manner. This film 2 can for example be made of polyethylene, methacrylate, Polyvinyl fluoride and the like.

To achieve an aesthetic appearance and to avoid the transparency of the film as much as possible 2 and thus the penetration of the radiation into the fiber mat 1 detrimental fogging, the contact between fiber mat 1 and film 2 should be as intimate as possible. The tightness can be ensured by wrapping the film 2 on the circumference of the fiber mat 1 between the carrier 3 and the fiber mat 1, as can be seen at 4.

Bonding, for example, with a methacrylate resin, polymerized in place has numerous advantages. This resin does not fall because of its transparency , is not very sensitive to UV, very resistant to aging and has high adhesive properties. The thermoplastic transparent If necessary, the film is treated in a corresponding manner to achieve less aging due to UV radiation.

In a third preferred embodiment of the invention a composite material ("solar mat") made of an unwoven, fibrous,

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Cell-like cavities or felted, made of a thermoplastic material fiber fleece mat be provided that allows the heat transfer fluid to trickle through and with two foils on both sides is glued from a thermoplastic material, of which at least one, the sun exposed film is transparent and the other film represents the carrier, which is impervious to the liquid trickling through. The slides are welded at the edges to seal the composite material. The falling film collector thus obtained can be stored and ready to use in roll form are cut to the dimensions of the respective, preferably insulating carrier and connected to them; The heat transfer fluid is supplied via upper feed channels and those provided in the lower part lower discharge channels.

It is also possible to use the actual trickle collector element with an insulating material such as a glass fiber mat or other rollable insulating material on the to connect the back facing away from the sunny side, without thereby the arbitrary rollability and cutability get lost.

In Fig. 3, a first such embodiment is one Solar collector shown according to the invention. The fiber mat 1, which has felted or cell-like cavities has two plastic films 2 adhering to it, the upper one of which is made of a thermoplastic material with an absorption spectrum in which the maximum solar energy is transmitted, while the material is in the far infrared is opaque (3 / um). The solar collector that can be unwound from rolls

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also has an insulating mat 5 and is between an upper feed channel 6 and a lower discharge channel 7 switched on.

In Fig. 4 there is another embodiment of such Collector according to the invention shown, which has a fiber mat 1 and a transparent film and a carrier film 2, which are possibly identical and switched between two headers 8, 9, for example made of polyethylene are. The tightness between the mat part and the. The manifold can be welded or glued, for example getting produced. Between the mat part and the carrier, for example a roof, a wall or the floor may be, an insulating means 5 is provided. The carrier film of this solar collector can be made of a cellular thermoplastic or an expanded polymer.

The method according to the invention for producing the above composite solar collectors is further characterized in that that the film permeable to solar radiation and the carrier are coextruded and at the same time Introduction of the inner fiber mat to be welded to this.

As can be seen from Fig. 5, the extruder consists of an extruder 11 for the carrier, a second extruder 12 for the film permeable to solar radiation and an unwinding device from which the nonwoven, cellular or fibrous nonwoven mat 13 unrolls and into a concealment room 1H arrives in which it is introduced between the two films which emerge from two flexible lips 15 of the coextrusion arrangement on both sides of the mat. the

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As can also be seen from the figure, the device has heating elements 16 on.

In contrast to conventional coextrusion devices for thermoplastics, the device according to the invention has the peculiarity that the cellular or fibrous fleece mat is introduced into the central part of the device, whereby it is avoided that the mat is exposed to high temperatures.

The transparent film and the carriers are generated at an elevated temperature in the range of I80 to 280 ⁰ C or with both surfaces of the cellular or fibrous mat in contact, to which they adhere.

The adhesion achieved in this way is then strengthened by that the complex structure thus obtained is pressed between a pressure roller 17 and a cooling roller 18. The rollers are equipped with water circulation and guarantee furthermore, rapid cooling of the composite material obtained.

As can be seen from Fig. 9, two compressed air cylinders 2-4 press the pressure roller 17 with a pressure of 1 to 5 kg at; In this way, pressure is exerted on the collector mat 11, 12, 13 when it is in contact with the cooling roller 18 comes.

A better lateral welding of the collector mat can also be achieved by a larger diameter of the pressure roller can be achieved in this area, as can also be seen from FIG.

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The material for the transmissive for solar radiation film is thermoplastic materials such as polyethylenes of high and low density polypropylenes which optionally up to 15 wt - containing% polyethylene, polyvinyl chloride, polyvinyl fluoride, polyamides, polycarbonates, acrylics and polyesters chosen, said. Films can optionally be connected to a second transparent film which is insensitive to UV radiation and which serves to protect the first film against aging.

The thickness of the film permeable to solar radiation varies depending on the plastic material in question from 50 to 200 µm.

To prevent or at least delay the photochemical Degradation of the plastics used by UV radiation can also differ from the materials in question Additives or certain pigments such as carbon black or titanium dioxide are introduced.

Recommended for every class of plastic materials Thereby certain additives, which are listed in the following list together with the order of magnitude of the desirable concentrations are listed:

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Polymer material UV protection agent Concentration (%) Polyethylene Benzophenone 0.5 high and low Benzotriazole - ger density t-butylphenylsali- - cylate Polypropylene Benzophenone 0.15 to 1 % Organometallic compound applications (e.g. from Ni) PVC Benzotriazole 0.5 to 1 % Benzophenone Cyanoacrylate and / or pigments: Salts of barium, Cadmium, zinc, lead Unsaturated poly Methyl methacrylate ester and / or benzotri 0.2 azole Polycarbonates Benzotriazole Benzophenone 0.5 Polyurethanes Isocyanates -

The additives are mostly added to the granulate and introduced into the plastic material during extrusion.

As a material for the cellular fiber fleece

According to the invention, mats are mostly, but not exclusively, Materials are used that consist of long fibers made of poly-

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propylene, polyamide or polyester or corresponding mixtures of such fibers. The material lies in the form of a very airy mat a few mm thick, through which a heat transfer fluid with a throughput of 100 to 300 l / h can flow through it per meter length; the mat must have sufficient mechanical strength so that it does not breaks when passing through the coextrusion device. The fibers of the nonwoven mat also contain a green one or black dye that is added to the synthetic resin during granulation, i.e. before fiber production.

The carrier film may be made of the same materials as the solar radiation transparent film, but will preferably selected from low density polyethylenes and polyamides. Its thickness is greater than that of the radiolucent Films and is of the order of a few mm, for example 1 to 3 mm.

The carrier can furthermore advantageously be carried out by introducing a substance which, when exiting the extrusion device goes into gaseous state, can be made lighter in the synthetic resin, for example by using Azodicarbonamide, which decomposes to release nitrogen and carbon dioxide, which form corresponding bubbles, causing them the thermal insulation properties of the carrier can be improved. A nucleating agent can also be added here, with which vesicles of uniform size can be achieved.

The manifolds are cylinders made of metal or plastic. Due to their corrosion resistance, they are lightweight Attachment and its light weight are preferably made of plastic.

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In Fig. 6 there is such a cylindrical manifold 22 shown, which consists of plastic and along a surface line has a slot 23.

As shown in FIG. 7, it is in accordance with the invention possible to attach the corresponding connections by welds 9, 10; the connections can also go straight through Be made extrusion, as shown in FIG.

The diameter is 1 to 3 cm. The manifolds are made of high or low density polyethylene, propylene, PVG or polyamide.

The connection with the collector mat takes place as follows:

. First, the film 12 and the carrier 11 of the fiber fleece mat at the mat end to a length of about 1 cm detached and glued to the outside of each tongue. In particular In cases, especially when the two materials are similar, the connection can also be made by welding. The resistance and tightness of this connection can also be achieved by welding on plastic rods 25, 26 made of the same material as the collector 12 can be raised on the outer sides of the tongues. Film and carrier are in place then within the weld.

The collecting pipe is a few cm longer than the collector mat . The header pipes are welded tightly at their ends or connected to the circuit for water or another heat transfer fluid.

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example

A collector mat according to the invention consists of one Polyamide 6 fiber mat with a thickness of 5 mm. The film is made of a low density polyethylene with a UV protective agent; its thickness is 100 µm.

The carrier consists of a low density polyethylene with 1 % azodicarbonamide and a nucleating agent. Its thickness is 1 mm.

The die temperature is 280 ⁰ C, the pulling speed of 3 m / min. By virtue of the construction of the "apparatus of the present invention", the residence time of the mat is sufficiently short that the temperature inside it remains below the melting point of the fibers. In contrast, its outside surfaces are heated by contact with the film and backing that are adhered to them .

The collector mat according to the invention or the solar collectors produced therefrom can be due to their novel Adapt the concept to all suitably aligned surfaces, which means a further application advantage.

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Claims (12)

Expectations y Rollable collector mat for falling film solar collectors, characterized by a nonwoven mat made of a thermoplastic material (I, 13) on both sides with coextruded films (2; 11, 12) is coated from a thermoplastic material, which are tightly welded at the edges, wherein one film is exposed to solar radiation and is correspondingly radiolucent and the other one opposite the heat transfer fluid trickling through the collector fleece mat is a tight carrier, as an upper header and a lower header (8, 9; 22) provided at the bottom for the circulating heat transfer fluid. 2. collector mat according to claim 1, characterized by a permeable for the solar radiation film (2) made of a high among polyethylenes and low density, polypropylene with optionally up to 15 wt -.% Polyethylene, polyamides, polycarbonates, polyvinyl chloride, polyvinyl fluoride and acrylic resins and Polyesters selected thermoplastic material. 3. Collector mat according to claim 1 or 2, characterized in that that the thermoplastic materials contain appropriate additives and suitable pigments as UV protection agents. 710- (3496/3597) -SF-E 909821/0590 4. Collector mat according to one of claims 1 to 3, characterized in that that the carrier film (2) made of a low density polyethylene or a polyamide as a thermoplastic There is material which, if necessary, has a lower density due to foaming or gas content. 5. Collector mat according to one of claims 1 to ¹ J, characterized in that the fiber fleece mat (1) consists of a dark-colored thermoplastic fiber fleece made of polypropylene, polyamide, polyester or mixtures thereof. 6. Collector mat according to one of claims 1 to 5, characterized in that the fiber fleece mat (1) has a thickness of 1 ' to 10 mm and allows a throughput of heat transfer fluid of 100 to 300 l / h per meter of length. 7. collector mat according to one of claims 1 to 6, characterized in that that it has as manifolds (8, 9; 22) cylinder made of plastic, which has a slot (23) along a Have surface line in which the fiber fleece mat is inserted, the two foils being glued to the collector, welded or squashed. 8. A method for producing the collector mat according to any one of claims 1 to 7, characterized in that the radiation-permeable Film and the carrier film are produced from two extruders of a special coextrusion device in the middle part of which a nonwoven mat is introduced and at the same time welded to the extruded foils, whereupon the ends of the 'collector mat produced in this way are glued, welded or inserted into suitable collecting pipes. 9. The method according to claim 8, characterized in that the 903821/0590 Extrusion temperature be selected for the films depending on the nature of the thermoplastics used between 18O and 280 ⁰ C, and the dwell and Abrollzeit of the nonwoven material sufficiently short that the temperature inside the material remains below its melting point. 10. The method according to claim 8 or 9, characterized in that the mutual adhesion between the three the collector mat constituent layers by guiding in a short, common part at the end of the coextrusion device is generated and reinforced by pressing between a pressure roller and a cooling roller. 11. Use of the collector mat according to one of claims 1 to 7 in solar systems. 12. Use of the collector mats according to one of claims 1 to 7 in solar systems for swimming pool heating. 9098 2 1/0590