WO2011041818A2

WO2011041818A2 - Solar collector

Info

Publication number: WO2011041818A2
Application number: PCT/AT2010/000381
Authority: WO
Inventors: Herbert Huemer
Original assignee: Xolar Renewable Energy Gmbh
Priority date: 2009-10-09
Filing date: 2010-10-11
Publication date: 2011-04-14
Also published as: WO2011041818A3; DE112010003991A5

Abstract

The invention relates to a solar collector (1) comprising at least one absorber material (2) for heating a heat-absorbing fluid and a cover (3, 10, 17) for the absorber material (2, 11), said cover (3, 10, 17) being light-permeable in at least some sections thereof and being constituted of at least one chamber (4, 12, 13, 19, 20, 21, 22, 23, 24, 25, 26) that can be inflated by means of a filling fluid.

Description

solar collector

The invention relates to a solar collector with at least one absorber material for heating a heat-receiving fluid and an at least partially transparent cover for the absorber material.

In conventional solar collectors glass or plastic covers are usually used for a flowed through by a fluid to be heated or at least in thermal contact with this absorber element or absorber material. One

The purpose of these covers is to ensure protection of the absorber material against the weather. Another task of the covers is often to couple solar radiation and pass it on to the absorber material. A disadvantage of the known embodiments, however, is that, depending on the outside temperatures, an undesired heat exchange with the environment may occur, which may result in exceeding or falling below a desired temperature of the heat-absorbing fluid. Thus, the temperature of the fluid to be heated in the summer may be well above a desired temperature, while it may come in winter due to lower outside temperatures to below the desired temperature of the fluid to be heated. Another disadvantage of known solar collectors lies in the fact that the thermal insulation properties of the solar collectors usually can not be adapted to external circumstances, since the thermal insulation is fixed by the once attached and no longer changeable cover

It is therefore an object of the invention to provide a solar collector, with which an optimal isolation of the absorber material in dependence on external conditions, such as the ambient temperature, is possible. This object is achieved with a solar collector of the aforementioned type according to the invention that the cover is formed at least from at least one inflatable with a filling chamber The solution according to the invention makes it possible, by changing the cover covering the absorber material, to change the insulating properties of the cover as a function of weather conditions and annual or times of day by introducing or discharging filling fluid. In addition, the transport and storage properties of the solar collector are substantially improved by the inventive solution. So the whole is

If the filling fluid is exhausted, lightly collapse the collector to a small pack size. Also, the weight of the solar collector can be significantly reduced by the inventive solution. In order to ensure a simple filling and emptying of the collector construction with filling fluid, the cover may have at least one valve for changing the amount of the fluid contained in the at least one inflatable chamber uids.

Very good insulating properties of the cover can be achieved in that the filling fluid is a gas or gas mixture

An inexpensive and easy-to-use variant of the invention provides that the fluid is air. A good thermal shielding of the absorption material can be achieved by the cover covering the at least one absorber material at least in a direction of light incidence and away from the light incidence direction covered

The thermal insulation of the absorption material can be improved even further by the cover essentially completely surrounding the absorbent material.

In order to enable a flow of the heat-absorbing fluid, for example water to be heated, the cover can have at least one inlet and at least one outlet opening for the heat-absorbing fluid.

A particularly easy-to-use embodiment of the invention provides that the cover and the absorber material are integrally formed with each other. According to a variant of the invention, it is provided that inside the space bounded by the cover and outside of at least one chamber hose-like flow chambers which are in contact with the at least one absorber material and are absorbed by the heat are arranged are. By means of this variant of the invention, optimum heat transfer to the fluid to be heated can be achieved.

In addition, the at least one chamber may be coated with the absorber element on a side wall section associated with at least one of the flow chambers. By this embodiment of the invention, the heat transfer to the heat-absorbing fluid can be further improved,

An advantageous development of the invention provides that at least one side wall of at least one flow chamber is formed by an outer surface of the at least one chamber. According to this development of the invention, it is possible to simplify the construction of the solar collector and thus to minimize the production costs. Moreover, in the case of coating the chamber with an absorber material by the short heat transfer path, optimum utilization of the radiated energy can be achieved. A particularly favorable embodiment of the invention provides that the flow chambers are formed by faces of the cover facing the interior bounded by the cover and webs connected to these surfaces. This embodiment of the invention makes it possible to integrally form the lines required for a flow of the solar collector with the heat receiving fluid with the cover and so to achieve a simple construction of the solar collector. The assembly and storage of the solar collector are considerably simplified by this variant of the invention

A variant of the invention, which is characterized by very good shaping properties and by also very good achievable absorption properties, provides that the cover and the webs are made of plastic. Due to the good absorption properties of polymers over the entire solar spectral range, a very efficient conversion of the irradiated energy into thermal energy can be achieved. The absorber material and / or the cover may have a thermotropic coating, which switches to a lower absorption value of the sunlight upon reaching a certain absorber temperature. For example, the thermotropic coating may be made to change color from a dark color value, such as black, to a lighter color value upon reaching a certain temperature

Furthermore, the surface of the absorber material can also be provided with a highly selective coating in order to reduce the heat radiation. In this way, a wavelength-selective absorption can be achieved, so that on the one hand there is a high absorption for visible light and on the other hand a low emissivity is given in the near infrared which ensures that less heat radiation is emitted.

The production of the solar collector can be simplified, that the cover is made of a film. In particular, the use of weldable films is very well suited for the production of the cover, since with these films almost any desired

Shaping can be achieved, so that it is possible with this variant of the invention to easily produce solar panels of any shape and size. Thus, for example, adaptations of the solar collector without any problems can be made to outside conditions.

According to a further advantageous variant of the invention, the cover has on its surface a large compared to the wavelength of the light structuring. In this context, a structuring is understood to mean that the local surface normal of the surface of the cover does not always coincide with the global surface normal of this surface. The term "large" in the present context means that the structuring of the surface is so large that diffraction phenomena are negligible and the geometric optics is applicable

According to an advantageous variant of the invention, the cover can have a plurality of chambers in a flow connection with one another for receiving the filling fluid. In this embodiment of the invention, individual chambers filled with the filling fluid are created by the chambers, whereby the insulating properties are improved can, while on the other hand, by the connection of the chambers with each other a common addition and discharge of the chamber is favored.

A development of the above-mentioned variant of the invention provides that the structuring of the surface of the cover is determined by the shape of the chambers. This embodiment of the invention has the advantage that the transmission behavior for sunlight, insofar as it is determined by the surface geometry of the cover, can be matched to the insulating properties of the cover determined by the shape of the chambers. This makes it possible to produce optimized solar collectors for different locations and operating conditions.

The insulating properties of the cover can be significantly improved if the chambers are arranged in the form of an at least two-row matrix, so that a central chamber has at least three adjacent chambers, wherein all the chambers are in fluid communication with each other. By this embodiment, a vertical air circulation between the chambers of a column of the matrix can be very efficiently prevented, whereby an effective thermal separation of more internal chambers of the more outer chambers of the cover can be achieved. However, in spite of the substantial improvement of the insulation properties, the filling of the chambers with the bonding fluid is not adversely affected by the connection of the chambers to one another. Of course, the same applies to the omission of the filling fluid from the cover. The chambers may be made of mirrored films, one to reduce heat radiation. An advantageous development of the variant of the invention mentioned in the preceding paragraph provides that the chambers of the matrix each have at least one opening to each immediately adjacent chamber of the same row, wherein at least one chamber of a row of the matrix additionally at least one opening to at least one in By this embodiment, it is particularly reliable to ensure that all the chambers of the matrix can be filled together with the filling fluid, without the insulation properties being impaired as a result of the realization of this property vertical air circulation within the cover can only take place between selected chambers. In order to facilitate the mounting of the solar collector, the solar collector may have a cover or the absorber material surrounding at one edge surrounding frame or eyelets.

The attachment of the cover in the frame is facilitated by the fact that the cover has at least one edge projecting holding surfaces and on the frame with the holding surfaces cooperating holding elements are arranged, wherein the retaining surfaces of the at least one edge can be fixed by means of the holding elements on the frame.

A simplification of the assembly of the solar collector can be achieved in that the holding elements are designed as clamp closures, wherein the holding surfaces in an open state of the clamping closures between clamping surfaces of the clamp closures can be inserted.

The invention together with further advantages will be explained in more detail below with reference to some non-limiting exemplary embodiments, which are illustrated in the drawings, in which show schematically:

1 is a schematic diagram of a first variant of a solar collector according to the invention;

FIG. 2 shows a schematic diagram of a second variant of a solar collector according to the invention; FIG.

Fig. 3 is a section through a part of a third variant of an inventive

Solar collector;

Fig. 4 is a plan view of a solar collector according to the invention and

Fig. 5 is a side view of a cover with Klenunmitteln for attaching the cover to a frame. By way of introduction, it should be noted that in the differently described embodiments, identical parts are provided with the same reference numerals or identical component names, wherein the disclosures contained in the entire description can be mutatis mutandis to identical parts with the same reference numerals and component names. Also, the position information selected in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to a new position analogous to the new situation. Furthermore, individual features or combinations of features from the various exemplary embodiments shown and described may also represent separate solutions in their own right, according to the invention or in accordance with the invention.

The figures are described coherently and comprehensively.

According to FIG. 1, a solar collector 1 according to the invention has an absorber material 2 for heating a heat-absorbing fluid, for example water. The term "absorber material", as it is understood in this document, encompasses not only coatings and layers but also independent absorber elements Thus, the absorber material 2 can be both a coating applied to another component and an independent component, such as, for example Aluminum block through which the heat-absorbing fluid flows.

The surface of the absorber material 2 may be provided with a highly selective coating to reduce the heat radiation. In this way, a wavelength-selective absorption can be achieved, so that on the one hand there is a high absorption for visible light and on the other hand a low emissivity is given in the near infrared which ensures that less heat radiation is emitted by the absorber material 2.

The absorber material 2 is covered by an at least partially transparent cover 3. The cover 3 can be formed from at least one chamber 4 which can be inflated with a filling fluid. The filling fluid used is preferably a gas or gas mixture, for example air. The use of air as filling fluid has the advantage that in this way a filling of the chamber 4 is possible in a very simple manner. With the Cover 3 according to the invention makes it possible to achieve excellent thermal insulation of absorber material 2.

The absorber material and / or the cover may have a thermotropic coating, which switches to a lower absorption value of the sunlight when a certain absorber temperature is reached. The thermotropic coating may, for example, be designed such that when a certain temperature is reached, black changes to a lighter color value , For insertion and discharge of the filling fluid into the chamber 4, the cover 3, a valve 5, for example, have a two-way valve. Thus, depending on external conditions, such as temperature, year or time of day, a change in the amount of filling fluid contained in the at least one inflatable chamber can be effected via the valve 5.

The cover 3 and the chamber 4 may be in communication with a stationary fluid pump 6, wherein the valve 5 may be connected between. The fluid pump 6 may be adapted to pump both fill fluid into and out of the chamber 4. In this way, a fully automatic change of the amount of filling fluid contained in the chamber 4 can be realized. Thus, the fluid pump 6 could be connected to a controller 7, which actuates the fluid pump 6 as a function of the ambient conditions or according to a predetermined schedule. In this way, an optimal adaptation of the insulation properties to external influences can be achieved. For example, during the day, the amount of fill fluid in the chamber 4 could be reduced and thus the thermal insulation capability of the cover 3 reduced to prevent overheating of the heat-accepting fluid. While at night, the amount of fill fluid contained in the chamber 4 could be increased to achieve higher thermal insulation, thereby avoiding or at least substantially retarding unwanted cooling of the heat-accepting fluid. It should also be noted at this point that, instead of a single fluid pump 6, it is of course also possible to provide pumps for the intake and exhaust of the filling fluid. However, the stationary arrangement of a fluid pump 6, as described above, is not necessary for realizing the invention, so the fluid pump 6 could be removed again after the cover 3 has been inflated. As shown in FIG. 1, the cover 3 may be a chamber enclosing the absorber material 2. In order to achieve a good thermal insulation of the absorber material 2, the cover 3 may cover the absorber material 2 at least in a light incident direction and facing away from the light incident direction side. The light incident direction is indicated in the figures by wavy arrows. The cover 3 may for example be formed tubular or bag-shaped, so that the Absorbermateria], for example, a flowed through by a fluid to be heated or the fluid receiving metal block, can be easily introduced into the cover.

At the open end regions or at the open end region, the cover 3 can have a protruding edge with closure means, for example a hook-and-loop fastener. Also, an open end region of the cover 3 can be closed after introduction of the absorber material by welding or gluing, so that the absorber material 2 differs from the Cover 3 is substantially completely surrounded. Welding or bonding edges of the cover 3 is possible, in particular, when a plastic, for example a weldable or glued foil, is used as the material for the cover.

In order to enable an inflow and outflow of the heat-receiving fluid, corresponding openings for the required supply 8 or discharges 9 can be provided on the cover 3.

According to the variant of the invention shown in Fig. 2, the cover 10 and the at least one absorber material 11 may be integrally formed with each other. For example, a chamber 12 that can be filled with a fluid can be coated with the absorber material 11. Between the absorber material 11 and the surface of the chamber 12, further layers may also be arranged, for example the above-mentioned thermotropic and / or highly selective coating. Furthermore, within the space bounded by the cover 10 and outside the chambers 12 and 13 filled with the filling fluid, the cover may include tube-like flow chambers 14 for the heat-absorbing fluid. The flow chambers 14 may be formed by webs 16 bounded within the space bounded by the cover 10 and the surfaces 15 of the cover 10 pointing into the interior of this space. The cover 10 and the webs 16 may be formed of plastic, for example of a plastic film.

The flow chamber 14 are in fluid communication with each other, so that the heat-absorbing fluid can flow through all the chambers. At one end of the hose-like flow chambers 1, the feed line 8 opens and at the other end the discharge 9 for the heat-absorbing fluid.

The flow chambers 14 may be in contact with the absorber material 11, for example, at its portion facing the light incident side. This may be the case in particular when an upper side wall of one of the flow chambers 14 is formed by the chamber 12 and the chamber 12 therewith the absorber element 11 is coated. As can be seen from Figure 2, the cover 10 may have on its surface a large compared to the wavelength of the light structuring, such as a wave or rib shape. The patterning of the surface of the cover 10 may be determined by the shape of the chamber 12. In principle, however, it is also possible that elements 10 for structuring the surface are applied to the cover, for example in the form of plastic prisms. In the latter case, the structuring of the surface is not or not entirely determined by the shape of the chamber 12.

The surface shape of the cover 10 may for example be selected so that in a fully inflated state of the cover 10 optimal reflection reduction is ensured for most non-perpendicular light incidence angle

The optimum shaping of the surface of the cover 10 can be determined, for example, by ray tracing methods. Basically, the shape of the surface is the Cover 10 freely selectable and can be selected depending on the environmental conditions at the site.

However, the surface structure may also be such that radiation is reflected under typical light incidence angles for very hot annual times, for example midsummer. This effect can also be enhanced by a corresponding reflective coating of the surface, wherein the reflection behavior of the coating depends on the angle of incidence. Furthermore, a cover 17 according to the invention, as shown in FIG. 3, can also have an antireflection coating 18 in the form of a sub-wavelength structure or a thin-film coating for reducing Freneic reflections. The antireflection coating 18 may be attached to the outer surface or, for example, also on all of the light incidence side facing portions of the cover 17, so also on the inner walls of the cover 17. In this way, a large part of the radiation incident on the surface of the cover 10 can be conducted to the absorption material 11.

According to the variant of the invention shown in FIG. 3, the cover 17 according to the invention can also have a plurality of chambers 19, 20, 21, 22, 23, 24, 25, 26. The chambers 19, 20, 21, 22, 23, 24, 25, 26 can be arranged in the form of an at least two-row matrix, so that a central chamber 21, bzw.24 at least three adjacent chambers 22, 23, 24 and 25, 26th 21, wherein all of the chambers of the cover 10 may be in fluid communication with each other. The chambers 19, 20, 21, 22, 23, 24, 25, 26 of the matrix may each have an opening to each immediately adjacent chamber 19, 20, 21, 22, 23, 24, 25, 26 of the same row. Apart from the openings to the adjacent chambers in the same row, the chambers 19, 20, 21, 22, 23, 24, 25, 26 may be closed. However, at least one chamber 19, 20 of a row of the matrix may additionally have at least one opening to at least one chamber 19, 20 located in the same column of the matrix with it. For example, these chambers 19, 20 could lie at the edge of the matrix. By the embodiment shown in Fig. 3 can be achieved particularly good insulation properties, since a vertical air circulation between the chambers 19, 20, 21, 22, 23, 24, 25, 26 can be prevented.

As can be seen from FIG. 4, the solar collector 1 can have a frame 27 surrounding the cover 10. The arrangement in the frame 27, the installation of the solar collector 1 at its site can be much easier.

According to FIG. 5, the cover 10 may have holding surfaces 28 protruding from an edge for attachment to the frame 27. On the frame 27 cooperating with the holding surfaces 28 holding elements 29 may be arranged. By means of these holding elements 29, the holding surfaces 28 can be fixed to the frame 10.

As is further apparent from FIG. 5, the holding elements 29 can be designed as clamping closures, wherein the holding surfaces 28 can be inserted between clamping surfaces 30, 31 of the clamping closures in an opened state of the clamping closures. The

Clamping surfaces 30, 31 of a clamping closure can be moved and fixed against one another, for example, by actuating a lever 32.

At the edge of the cover 10 and eyelets can be attached to facilitate mounting of the solar collector. In the event that eyelets are provided, the use of a frame is not essential.

Finally, it should be noted that the exemplary embodiments only show possible embodiments of the solution according to the invention, wherein the invention is not limited to the specific embodiments illustrated. In particular, combinations of the individual embodiments are possible with each other, these variations are due to the teaching of technical action of the subject invention in the skill of those working in this technical field expert. There are also all conceivable embodiments that realize the solution ideas underlying the invention and are not explicitly described or illustrated or by combinations of individual details of the illustrated and described variants are possible, including scope of protection also covers the protection extends to the individual Components of the device according to the invention, insofar as they lend themselves to the realization of the invention.

REFERENCE NUMBERS

1 solar collector

2 absorber material

3 first variant of a cover

4 inflatable chamber

5 valve

6 fluid pump

7 control

8 supply line for a heat-absorbing fluid

9 discharge for a heat-absorbing fluid

10 second variant of a cover

11 absorbent material

12 inflatable chamber

13 inflatable chamber

14 flow chamber

15 outer surface of a chamber

16 footbridge

17 cover

18 anti-reflective coating

19 inflatable chamber

20 inflatable chamber

21 inflatable chamber

22 inflatable chamber

23 inflatable chamber

24 inflatable chamber

25 inflatable chamber

26 inflatable chamber

27 frame

28 holding surface

29 holding element

30 clamping surface

31 clamping surface

32 levers

Claims

P a t e n t a n s r e c h e

1. Solar collector (1) with at least one absorber material (2) for heating a heat-absorbing fluid and an at least partially translucent cover (3, 10, 17) for the absorber material (2, 11), characterized in that the cover (3, 10, 17) is formed at least from at least one inflatable with a filling fluid chamber (4, 12, 13, 19, 20, 21, 22, 23, 24, 25, 26)

2. Solar collector according to claim 1, characterized in that the cover (3, 10, 17) at least one valve (5) for changing the amount of in the at least one inflatable chamber (4, 12, 13, 19, 20, 21, 22, 23, 24, 25, 26) contained filling fluid.

3. Solar collector according to claim 1 or 2, characterized in that the filling fluid is a gas or gas mixture

4. Solar collector according to one of claims 1 to 3, characterized in that the fluid is air. 5. Solar collector according to one of claims 1 to 4, characterized in that the cover (3, 10, 17) which covers at least one absorber material (2, 11) facing at least one light incident direction and a light incident direction facing away from the side. 6. Solar collector according to one of claims 1 to 5, characterized in that the cover (3, 10, 17) surrounds the at least one absorber material (2, 11) substantially completely

7. Solar collector according to claim 6, characterized in that the cover (3, 10, 17) has at least one inlet opening (8) and at least one outlet opening (9) for the heat-absorbing fluid.

8. Solar collector according to one of claims 1 to 7, characterized in that the cover (3, 10, 17) and the at least one absorber material (2, 11) are integrally formed with each other. 9. Solar collector according to one of claims 6 to 9, characterized in that within the space bounded by the cover (3, 10, 17) and outside the at least one chamber (4, 12, 13, 19, 20, 21, 22, 23, 24, 25, 26) hose-like, with the at least one absorber material (2, 11) in contact and by the heat aufoehmenden fluid flowing through each other and in flow communication standing flow chambers (14) are arranged.

10. Solar collector according to claim 9, characterized in that the at least one chamber (12, 13, 19, 20, 21, 22, 23, 24, 25, 26) to a at least one of the flow chambers (14) associated side wall portion with the absorber element (1) is coated. 1. Solar collector according to claim 9 or 10, characterized in that at least one side wall of at least one flow chamber (14) from an outer surface of the at least one chamber (12, 13, 19, 20, 21, 22, 23, 24, 25, 26) is formed.

12. Solar collector according to one of claims 9 to 11, characterized in that the flow chambers (14) in the of the cover (10, 17) bounded interior facing surfaces (15) of the cover (10, 17) and connected to these surfaces Webs (16) are formed.

13. Solar collector according to claim 12, characterized in that the cover (3, 10, 17) and the webs (16) are formed from plastic.

14. Solar collector according to claim 13, characterized in that the cover (3, 10, 17) is made of a film

15. Solar collector according to one of claims 1 to 14, characterized in that the absorber material (2, 11) and / or the cover (1, 10, 17) has a thermotropic coating. 16. Solar collector according to one of claims 1 to 15, characterized in that a surface of the absorber material is provided with a highly selective coating

17. Solar collector according to one of claims 1 to 16, characterized in that the cover (3, 10, 17) on its surface in comparison to the wavelength of the

Light has great strukrurierung.

18. Solar collector according to one of claims 1 to 17, characterized in that the cover (3, 10, 17) a plurality of mutually fluidly connected chambers (12, 13, 19, 20, 21, 22, 23, 24, 25, 26) for receiving the filling fluid.

19. Solar collector according to claim 17 or 18, characterized in that the structuring of the surface of the cover (3, 10, 17) by the shape of the caramels (12, 13, 19, 20, 21, 22, 23, 24, 25, 26) is determined

20. Solar collector according to claim 18 or 19, characterized in that the chambers (19, 20, 21, 22, 23, 24, 25, 26) are arranged in the form of an at least two-row matrix, so that a central chamber (21, 24) at least three adjacent chambers (21, 22, 23, 24, 25, 26), wherein all the chambers (19, 20, 21, 22, 23, 24, 25, 26) are in flow communication with each other.

21. Solar collector according to claim 20, characterized in that the chambers (19, 20, 21, 22, 23, 24, 25, 26) of the matrix in each case at least one opening to each immediately adjacent chamber (19, 20, 21, 22, 23, 24, 25, 26) of the same row, with at least one chamber (19, 20) emerging from the matrix in addition to at least one opening to at least one chamber (19, 20) located in the same column of the matrix. having.

22. Solar collector according to one of claims 1 to 21, characterized in that it just the cover (3, 10, 17) and the absorber material (2, 11) on an edge surrounding surrounding frame (27).

23. Solar collector according to claim 22, characterized in that the cover

(3, 10, 17) on at least one edge projecting holding surfaces (28) and on the frame (27) with the holding surfaces (28) cooperating holding elements (29) are arranged, wherein the retaining surfaces (28) of the at least one edge by means of Retaining elements (29) on the Kähmen (27) are fixable.

24. Solaikollektor according to claim 23, characterized in that the holding elements (29) are designed as clamp closures, wherein the Halteftächen (28) in an open Zitand the clamping closures between clamping surfaces (30, 31) of the clamp closures are einle ^ r.