WO2013090964A2

WO2013090964A2 - Absorber for solar radiation

Info

Publication number: WO2013090964A2
Application number: PCT/AT2012/050199
Authority: WO
Inventors: Gerhard Huber; Christoph Zipko
Original assignee: Sun Master Energiesysteme Gmbh
Priority date: 2011-12-22
Filing date: 2012-12-18
Publication date: 2013-06-27
Also published as: WO2013090964A3; AT512172A4; AT512172B1

Abstract

The invention relates to a planar absorber (1) for solar radiation, having at least two plates (2, 3) which are arranged at a distance (4) from one another and form, at least in their peripheral region (5), a sealed cohesive connecting region (6) in which connecting sections (63, 64) of the plates (2, 3) are connected together, and which are connected via wall parts (17), extending transversely with respect to main surfaces (7, 8) of the plates (2, 3), for spacing apart the two main surfaces (7, 8) of the plates (2, 3). In this case, on at least one plate (2, 3), the connecting section (63) is offset with respect to the main surface (7, 8) of the first plate (2, 3) by a deformation directed in the direction of the other plate (3, 2), and the transversely extending wall parts (17) are deformed integrally from at least one of the plates (2, 3).

Description

Absorber for solar radiation

The invention relates to a planar absorber for solar radiation according to the preamble of claim 1, a solar collector with a planar absorber according to the preamble of claim 25, a method for producing a planar absorber for solar radiation according to the preamble of claim 29 and an apparatus for producing a planar absorber according to The preamble of claim 36 and the use of the device according to claim 38.

The main function of a solar absorber, hereinafter referred to simply as absorber, is to absorb as much as possible of direct and indirect solar radiation and to deliver this absorbed energy as a result of heat transfer to a heat transfer fluid conducted through the absorber. An often used in use type of absorber are so-called flag absorber, in which the solar radiation is absorbed by sheets and is transmitted by means distributed on the sheet pipes to the flowing in the tubes heat transfer fluid. In this type of construction, the absorber surfaces result in a very uneven temperature distribution, since in the case of heat conduction, greater distances must be covered and higher temperatures of the absorber plate occur with increasing distance from the pipelines. The heat losses by radiation are increased in these zones and the efficiency of such flag absorber is not optimal.

In order to avoid this, absorbers that flow through over the entire area are sometimes used, in which the heat transfer fluid is passed through in a planar manner between two spaced-apart plates. For their preparation, the absorber-building plates are profiled and thereby formed transverse to the main surfaces extending wall parts and then these profiled plates are firmly bonded together. The disadvantage of such fully absorptive absorbers is the more elaborate production compared to flag absorbers, which is why solar absorbers which are flowed through over the whole surface are relatively seldom used despite better efficiency. An absorber type, in which a two-dimensional

Through flow is approximated, can be prepared by a so-called roll-bonding process, in which two sheets are coiled on one another, wherein flat flow channels are thereby produced by zones in which flow channels gebil- Det are before the rolling of the sheets are provided with a release agent and the flow channels are then inflated. However, this process requires extensive purification procedures and heat treatments to perform. The object of the invention is to provide an absorber with high efficiency, which is inexpensive to produce.

The object of the invention is achieved by a generic absorber with the characterizing features of claim 1. In contrast to the prior art, in which the plates are profiled and then materially bonded or plates are rolled flat and the flow channels are subsequently expanded, the production principle is effectively reversed in an absorber according to the invention and become the transverse to the main surfaces of the absorber plates extending wall parts directly during the joining process formed by a deformation of at least one of the plates by at least one plate of the compound sab cut offset by a directed toward the other plate deformation relative to the main surface and connected to the other plate. As a result, subsequently arched or inclined wall parts arise at the connection area. The production of the transverse wall parts is thus not necessary in a joining operation upstream or downstream additional manufacturing step and is a total of the production of such an absorber simple and inexpensive.

The connecting section is formed from a material section originally located in the main surface of a plate and is thereby also given a material-saving production of such an absorber. It is also possible that the transverse wall parts are also formed from both plates, whereby a greater distance between the two plates can be made or fixed. The cohesive connection of the two plates in the edge region thereof and possibly further connecting regions is thereby produced by the action of a joining force directed transversely to the main surfaces, whereby the material expansion is also effected to form the oblique wall parts. The two plates are pressed against each other in the connection area with such a high force that the two plate materials enter into a cohesive connection and thereby a pressure-tight connection is made and the heat transfer fluid can be sealed by the absorber.

The cohesive connection regions produced in the edge region of the two plates can run approximately parallel to the main surfaces of the two plates or can also be inclined relative thereto, as a result of which different cross-sectional geometries of such absorbers are possible.

The wall thicknesses of the individual plates in their main surfaces are chosen so that the finished absorber has sufficient rigidity for handling and receiving a pressurized heat transfer fluid, however, for reasons of material savings and better heat transfer, at least on the insolation side as possible small wall thickness can be provided. In the cohesive connection region, within the oblique wall parts or in the transition regions from the oblique wall parts to the main surfaces or the connection areas, the total wall thickness is less than the sum of the individual wall thicknesses of the two plates, which is directly related to the material expansion taking place during the connection process with the same volume of material , The material expansion in this case comprises a plastic deformation of the material areas originally located within the main surface and this requires exceeding the elastic deformability of the starting material, whereby permanent plastic deformation occurs The connection area is not brought to high temperatures during the joining process as in a welding operation, which is why no material changes take place of the materials involved, which could degrade the mechanical properties.

An advantageous embodiment of the absorber is that the wall thickness of at least one of the two plates increases from the connecting region in the direction of its main surface. Because the wall thickness increases from the connection area to the main area, in particular substantially uniformly and does not increase abruptly, such an absorber has a high mechanical strength and stability and will have high voltage levels. Achieved due to the smooth transition between the major surfaces and the connecting portions.

A further increase in the stability and mechanical load-bearing capacity of an absorber according to the invention is achieved if the absorber in addition to the edge region within the

Absorber surface has additional connection areas. These additional connection regions can be distributed in a point-like manner over the absorber surface or linear connection regions, whereby the orientation of the line-like connection regions can also influence the flow through the absorber with heat transfer fluid and thus also the temperature distribution within the absorber surface. These additional connection areas within the absorber surface cause, even when thin-walled plates are used, the two main surfaces of the plates without bulges remain substantially parallel to each other, even when the heat transfer fluid is pressurized.

Furthermore, the additional connection regions can occupy an area fraction of at least 50% of the absorber surface within the edge region, whereby although the proportion of the surface through which flows flows decreases, the mechanical stability of such an absorber is further increased.

The cavities lying between connecting regions can form a net-like, serpentine or harp-like structure within the absorber surface, as a result of which a heat dissipation which is largely uniform over the absorber surface is likewise achieved. The cohesive connection in the edge region of an absorber according to the invention and optionally in additional connection regions is preferably produced by means of an electromagnetic joining process (EMPT method Electromagnetic Pulse Technology) under the action of strong electromagnetic pulses on electrically conductive materials, which has the advantage that even coated board materials connected can be, since by the high contact forces occurring and the simultaneous material expansion, the two plate materials are approximated to each other except for distances corresponding to the lattice constants of the metals involved, whereby an intimate connection between the base materials of the plates is produced without An existing coating of the quality of the bond would be detrimental, since surface layers are torn open locally due to the high pressures and the material expansion. Due to the extremely pulse-like introduction of electromagnetic forces in the metallic plate material at least one of the connecting portions is moved at high speed in the direction of the second connecting portion and these two materials are intimately joined together due to extremely high surface pressures and therefore are pressure-tight connections, the Passage of heat transfer fluid allows. This is an extremely fast production process and therefore there are no microstructural changes in the board materials, since compared to welding processes only a negligible heat input into the board materials takes place.

In order to minimize temperature differences within the absorber surface, it is advantageous if at least one of the plates from the main surface in the inner cavity of the absorber has projecting ribs, in particular obliquely to the main flow direction of the absorber extend, preferably arranged as leaf ribs. By means of such ribs, a steering of the flow direction of the heat transfer fluid can take place within the absorber and, in particular, flow components oriented transversely to the main flow direction can be effected, as a result of which a more uniform temperature level overall is achieved across the absorber surface.

In order to improve the heat transfer from the outer plate acted upon by the solar radiation and thereby heated in the heat transfer fluid, it is possible that at least one of the plates of the main surface in the inner cavity of the absorber protruding projections, in particular in the form of spherical caps, pyramidal sections, conical sections , Cylinder segments or shaft sections. This causes a laminar flow on the inside of the absorber plate is avoided and a turbulent flow with improved heat transfer is promoted.

If the ribs and / or projections are made integrally by deforming a plate out of the main surface, the heat transfer enhancing components can be made directly from the originally flat plates and thus such embodiments of an absorber are inexpensive and can be produced materially. Furthermore, such a production can also be used in coated board materials. The deformation of the originally flat plates can be done, for example, by means of suitable presses with appropriate punches and dies before joining the plates.

An alternative way to produce such ribs and projections may be that the ribs and / or projections are made from a plate by an EMPT process. The ribs and projections can be done with this method before, simultaneously or after the cohesive connection of the edge regions of an absorber.

The connection areas can further define a closed, in particular stretched, cavity between the plates, which can be used as a heat pipe. The heat transfer fluid circulates in this case only within the absorber, where it evaporates by absorbing heat in the interior of the absorber and emits this heat by condensation on a heat exchanger to a subsequent to the absorber external heat cycle. The circulation inside the absorber is maintained by gravity or capillary forces.

Another advantage is an embodiment of the absorber in which at least one inlet or at least one outlet for heat carrier fluid is formed by an opening or passage extending parallel to the main surfaces of the plates in the edge region. The connections for the passage of heat transfer fluid can be done in this case cost at the same time with the production of cohesive edge bond of the two plates and the connections for inlet or outlet in the cross section of an absorber are oriented in the axial direction. For example, inlet and outlet can also be made using the EMPT method described above, for example by inserting prefabricated fittings between the two plates to be joined and sealingly sandwiching them in the course of rapid deformation and approximation of the two plates. The feedthroughs for such fittings can be preformed to pre-position the plates for the joining process in spite of the fittings sufficiently close to each other. Using the EMPT method, the connection pieces can be integrated pressure-tight directly during the joining process.

However, it may also be advantageous if at least one inlet or at least one outlet for heat transfer fluid is formed through an opening in the main surface of one of the plates is. In this case, the cohesive, tight edge bond of the absorber element can be produced very simply circulating and inlet and outlet can be introduced by introducing appropriate connecting pieces transversely to the absorber surface in subsequent manufacturing steps.

In order to achieve a uniform flow and optimal efficiency of the absorber, it is advantageous if inlet and outlet are arranged at the edge region substantially diametrically with respect to the center of the absorber. The entire absorber surface flows through it and is used for the heating of the heat transfer fluid.

By means of an embodiment of the absorber in which at least one of the plates on an inner surface facing the other plate has a coating of a material different from its main plate material, in particular of plastic and / or metal, it is possible to use plate main materials in which the Contact with the heat transfer fluid adverse effects, such as corrosion would cause used. There are therefore fewer restrictions for the selection of plate materials and cost-effective material combinations can also be used. An inner coating of the plate main material can thereby improve the heat transfer from the plate into the heat transfer fluid, as is desired, for example, in the solar radiation facing absorber plate, or even worsen, as it is advantageous for example in the solar radiation away from the absorber plate, because As a result, the heat loss to the underside of the absorber is prevented or reduced.

In order to improve the efficiency of the absorber according to the invention, it is advantageous if at least one of the plates has on a side facing away from the other plate outside a solar radiation selective or reflective coating. The selective coating is very well permeable to the frequency or wavelength of the solar radiation, but poorly transmissive to infrared radiation, ie heat radiation, whereby the absorber surface can very well absorb solar radiation but can emit little heat radiation and therefore the largest possible proportion the absorbed solar radiation can be transmitted as heat in the heat transfer fluid. A reflective coating can serve to redirect solar energy to a remote solar energy converter. An advantageous embodiment of the absorber may further consist in that one of the plates on a side facing away from the other plate outside with respect to the main surface towering protruding projections, in particular in the form of spherical caps, pyramidal sections, conical sections, cylinder segments or shaft sections. An outer side of the absorber plate provided with such projections can face the solar radiation, and the reflection properties or the radiation properties of the absorber can be advantageously influenced by the projections. Furthermore, air flows at the top of the absorber element can thereby be reduced, whereby heat losses due to convection, for example within a solar collector, can be reduced.

An advantageous embodiment of an absorber may consist in that the plates are made of different main materials, wherein in particular one of the two plates is preferably made of aluminum material or copper material and the other of the two plates is preferably made of stainless steel or coated steel sheet. An absorber made of different main board materials can optimally combine the advantages of the individual board materials. Thus, for example, the solar radiation facing absorber plate made of aluminum or copper sheet, which is characterized by a high thermal conductivity and therefore gives a good heat transfer to the heat transfer fluid, while the second, facing away from the solar radiation absorber plate, for example, made of stainless steel or coated steel sheet , which is inexpensive and ensures good mechanical stability of the absorber. Furthermore, it is possible to build the solar radiation away from the absorber plate made of plastic material or a metal plastic composite, which also heat losses to the absorber base can be reduced.

If bulge heights of the main surfaces of the two plates on curved wall parts are different sizes, the production of such an absorber can be facilitated by suitable choice of the bulge heights or also the effectiveness and efficiency of the absorber can be favorably influenced. Thus, for example, the larger bulge can be made from the plate having a deformable base material, while the second plate is provided shohe with less bulge. Furthermore, it is also possible that one of the two plates in the connection region is substantially flat, so the connection sab cut has no offset to the main surface, whereby the absorber on one side has a smooth surface and thus less susceptible to soiling, for example, or such can be removed more easily. A smooth absorber surface is also subsequently easy to coat, so that, for example, a selective coating can be applied inexpensively. In particular, that plate, which is not deformed in the connection region and flat, be made of a thicker material, whereby such an absorber has a high mechanical stability.

If an absorber is designed so that in plates of different main materials that plate has a greater bulge shöhe whose main material has a greater coefficient of thermal expansion, causes this greater bulge height in a plate that they dodge when elongated due to temperature changes in the direction transverse to the main surface can, whereby mechanical stresses due to temperature changes turn out lower. When using absorbers in solar collectors, operating temperatures of -40 ° C. to 200 ° C. (corresponding to the stagnation temperature) and beyond are possible, which is why, in particular when using different plate materials within an absorber, the disadvantageous effects of thermal linear expansion should be avoided.

Advantageous embodiments of an absorber according to the invention are present when the distance between the two main surfaces of the plates from a range with a lower limit of 1 mm, preferably 2 mm, in particular 3 mm and an upper limit of 30 mm, preferably 10 mm, in particular 6 mm is selected. These distances between the two plates can be easily made by the methods already described, and such absorbers are useful for both small and high heat flux collector systems. Absorbers with smaller spacings between the two main surfaces are preferably of advantage for high-flow systems, while the absorbers have larger distances and greater heat transfer fluid content for so-called low-flow systems.

Flow systems can be used .. Especially at small distances between the two plates results in a very low height of the absorber and are characterized populated solar panels by a very low overall height. larger Cross-sections of the flow channels or cavities in the interior of the absorber can be advantageous in systems in which water is not used as a heat transfer fluid but gases, so about collectors produce the hot air. Even with absorbers with closed cavities in the form of heat pipes larger cross-sections of advantage and no problem in terms of operating weight, since the cavities in this case are only partially filled with heat transfer fluid.

To achieve larger flow cross sections; For example, the plates may be convexly convexed between adjacent connection areas. This can e.g. be effected by a pressure applied after the joining operation of the cavities, whereby the two plates locally increase their distance between adjacent connection areas.

The wall thicknesses of the two plates can be selected from a range with a lower limit of 0.12 mm and an upper limit of 2.5 mm, wherein the two plates can also have different wall thicknesses. Thus, for example, is advantageous if the solar radiation facing outer absorber plate has a smaller wall thickness, since the heat transfer and the heat transfer is facilitated in the heat transfer fluid, while the greater wall thickness is preferably provided on the underside of the absorber, since the heat transfer as low as possible should be and here provides a greater wall thickness for a high mechanical stability of an absorber.

A further possible embodiment of the absorber can also consist in that an intermediate plate is arranged between the plates, which extends between two adjacent connecting regions and subdivides a cavity for heat transfer fluid located between the plates into two partial cavities separated from one another by pressure. As a result, two separate circuits for heat transfer fluid can be formed within the absorber. A circuit can be provided for the heat transport within the absorber and by means of heat transfer through the intermediate plate, these are transferred to a second, outwardly guided circuit. Such an intermediate plate may in particular consist of two different material layers and, for example, have a first surface of aluminum material and a second surface of copper material. Preferably, the plates forming the partial cavities are also provided on their inside with such the same material, whereby a circuit is enclosed in aluminum material and a second circuit is enclosed in copper material, whereby corrosion phenomena are avoided due to the meeting of different metals, which can not act as the heat transfer medium as both metals contacting electrolyte.

Another object of the invention is to provide a solar collector which is inexpensive to produce and has a high efficiency.

The object of the invention is achieved by a generic solar collector with the characterizing features of claim 25, whereby the beneficial effects of the absorber according to the invention also come in a so equipped solar panel to bear and can be availed. In particular, such a solar collector can be designed with a low overall height, whereby the integration in roof structures is facilitated and also the support structure for the absorber, for example in a frame collector or pan collector can be made slimmer and cheaper. The solar collector may further comprise an insulating element, can be reduced with the heat losses at the side facing away from the solar radiation side of the absorber.

If the distance between the outside of the absorber and the cover element is selected from a range with a lower limit of 1 mm, preferably 2 mm, in particular 5 mm and an upper limit of 50 mm, preferably 30 mm, in particular 15 mm this gap the heat transfer from the hot absorber to the cover and can be largely avoided by a relatively small distance convection phenomena within the solar panel. Although the thermal insulation effect of the air-filled gap is lower at the lower specified distances, such a collector is characterized by a very low overall height. A distance that is advantageous in practice for many environmental conditions is about 10 mm.

In order to optimize the heat output of the solar collector, the cover member may be formed from one or more glass layers or one or more plastic layers or a combination or mixed sequence of such. Depending on the respective prevailing, optimal working temperature, the cover element can be adapted to an optimum compromise of permeability for solar radiation and reduction of heat dissipation. Radiation is achieved. In particular, in cold outside temperatures results in a multi-layered construction of the cover with several intermediate air cushions optimal thermal insulation, since heat losses are reduced by convection within the solar panel.

Of advantage may also be an embodiment in which the cover has the solar radiation directing or concentrating or dissipating optical elements on an inner side facing the absorber. This measure makes it possible to influence the solar radiation impinging on and penetrating the cover element in its direction, and thereby also being able to influence the distribution of the radiation power on the absorber. It is thus possible, for example, to locally reduce the irradiation intensity by means of dispersive optical elements or to locally increase the intensity of irradiation by means of concentrating optical elements, as a result of which the temperature within the absorber surface can also be influenced. So it is possible, for example, to apply zones of the absorber, which are flowed through more strongly, with higher radiation intensity.

The covering element or elements may be formed, for example, from tempered glass, preferably with reduced iron content, PTFE (Teflon), PVF (Tedlar), ETFE (Hostaflon), polycarbonate, polymethyl methacrylate (PMMA). The plastic materials have the advantage that they can possibly also be produced as double-skin sheets or triple-skin sheets.

On the formation of Dämmelements at the bottom of the absorber is not discussed here, it can all thermal insulation materials are used, which have sufficient resistance to aging and heat.

A further object of the invention is to provide a method for producing a planar absorber, with which efficient absorber elements can be produced inexpensively. The object of the invention is achieved by a generic method with the characterizing measures of claim 29. The deformation of the plate material out of the main surface in a direction transverse thereto and the resulting production of the wall parts for distancing the two plates takes place in the same process step as the production of the cohesive connection. This manufacturing method is therefore simpler and faster than in known methods, in which in a first step, the plates are deformed so that the transverse to the main surfaces extending wall parts are prepared and in a further process step, the cohesive connection is made at the connection areas or a production according to the roll-bonding method described above. In the production of the cohesive connection material is offset from at least one of the two plates in the process according to the invention by forming relative to the main surface and this requires material expansion which allows the formation of the obliquely or transversely extending wall parts, fixed by the distance between the two plates and thereby the clear flow cross-section for the heat transfer fluid is permanently ensured.

To produce the integral connection of the two plates in the connection region or edge region, an electromagnetic joining process (EMPT) is preferably used. In this previously described method of electromagnetic pulse technology, which is also referred to as magnetic forming, the necessary forming and joining forces are introduced by pulsed action of electromagnetic forces on the conductive components of at least one of the two plates. In this case, either two plates to be joined are moved toward one another in a jerky manner or a first plate is supported by a stop or a base and the second plate is moved toward the first plate in a jerky manner. In order to achieve a sufficient material displacement and intimate, cohesive connection, it is advantageous if the plates are positioned relative to each other immediately before performing the electromagnetic joining process (EMPT) that between facing inner sides of the plates an exit distance, in particular between 0.5 mm and 3 mm. The two plates to be joined thereby move towards one another in the connection region with a very high relative speed and the effects according to the invention of the displacement of the connecting sections and the formation of the transverse wall parts are increased. It is also possible that the initial distance between the plates is produced by ribs and / or projections on at least one of the inner sides. These ribs or protrusions may be applied to at least one of the plates by pre-processing steps and then have to drive the two plates to carry out the electrical merely be superimposed on each other by the magnetic joining method, the ribs and / or projections already providing the correct initial distance for the subsequent electromagnetic joining process. As a further consequence, these ribs and / or projections can also advantageously influence the flow behavior of the heat transfer fluid in the finished absorber, as already described above. The initial distance can be smaller but also larger or equal to the distance between the two plates selected on the finished absorber.

An advantageous embodiment of the method may further consist in that applied on at least one of the plates on one of the other plate facing the inside of the cohesive connection before a coating of a material to the plate main material different material, in particular plastic and / or metal becomes. By coating a plate of the absorber element, it is possible to improve or mitigate the heat transfer properties between plate material and heat transfer fluid, depending on whether an increase or decrease in the heat transfer is desired. Furthermore, it is possible to reduce or prevent unwanted chemical reactions between the heat transfer fluid and the main plate material by the coating. An advantageous combination of materials consists, for example, of coating the inner side with a layer of copper material on a plate main material made of aluminum, for example by electrochemical means or by rolling or otherwise plating, whereby adverse chemical reactions between the absorber plates and the heat transfer fluid or subsequent copper pipes are avoided.

The manufacturing method according to the invention can also be applied in the form that on one of the plates on an outer surface facing away from the other plate before

Producing the cohesive connection, a layer of a solar radiation selective coating material is applied. In particular, by using the EMPT method, such selective coating materials can also be applied to an absorber element before joining the two plates, since these do not adversely affect the joining process and are not destroyed or adversely affected by the joining process itself. The manufacturing method can be further developed such that a linear cohesive connection region is formed by a series of overlapping partial connection regions, which are produced at least partially successively in time. In this way, even with a production device which can join only relatively small connecting regions in a materially joined manner, a large contiguous connection region can be produced in a plurality of time-sequential joining processes, as is required in the edge bond.

Another object of the invention is to provide a device with which a flat absorber for solar radiation with good solar efficiency can be produced economically.

The object of the invention is achieved by a generic device with the characterizing features of claim 36. With such a device, such an absorber can be produced very economically using the previously described EMPT process.

If, in this case, the coil arrangement extends in one piece or in several parts substantially over the entire edge region of the absorber, only a very short production time is required for producing such absorbers.

The invention also includes the use of a device according to claim 38 for the manufacture of a described absorber. For a better understanding of the invention, this will be explained in more detail with reference to the following figures.

In each case in a highly schematically simplified representation: FIG. 1 shows a view of a flat absorber;

FIG. 2 shows a section through an absorber according to FIG. 1 along lines II-II; FIG. 3 shows a section through a connection region of a further embodiment of an absorber;

4 shows a section through an absorber with protruding into the interior of the absorber rib or jump ahead;

Figure 5 is a view of an embodiment of an absorber with a special arrangement of ribs in the interior. 6 shows a section through a solar collector with an absorber according to the invention;

7 shows a possible embodiment of an inlet or outlet on an absorber according to the invention;

8 shows a further possible embodiment of an inlet or outlet in an absorber according to the invention;

FIG. 9 shows a section through an absorber according to FIG. 8 along line IX - IX; FIG.

10 shows a view of an apparatus for producing an absorber according to the invention;

FIG. 11 is a plan view of a device according to FIG. 10; FIG.

Fig. 12 is a plan view of another possible embodiment of a device for

Production of an absorber according to the invention;

13 shows a representation of a possible method variant for producing an absorber according to the invention;

14 shows an edge region of a possible embodiment of an absorber before

Joining process; 15 shows a section through a further possible embodiment of an absorber after the joining process.

By way of introduction, it should be noted that in the differently described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosures contained in the entire description can be mutatis mutandis to the same parts with the same reference numerals or component names. Also, the location information chosen in the description, such as top, bottom, side, etc. related to the immediately described and illustrated figure and are to be transferred to the new situation mutatis mutandis when a change in position. Furthermore, individual features or combinations of features from the different exemplary embodiments shown and described can also represent independent, inventive or inventive solutions. All statements on ranges of values in the description of the present invention should be understood to include any and all sub-ranges thereof, e.g. the indication 1 to 10 should be understood to include all sub-ranges, starting from the lower limit 1 and the upper limit 10, i. all subregions begin with a lower limit of 1 or greater and end at an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

Fig. 1 shows the view of a planar absorber 1 for receiving solar radiation and delivery of heat energy to a guided in the absorber 1 heat transfer fluid. The absorber 1 essentially comprises two plates 2 and 3 extending parallel to one another, which are arranged at a distance from each other at a distance 4 (see FIG. 2) and form a sealed, integral connection region 6 in their edge region 5. The illustrated absorber 1 has a rectangular basic shape, as is customary, for example, for installation in solar collectors, of course, deviating forms are possible. As shown in Fig. 2, the two plates 2 and 3 have two mutually parallel major surfaces 7 and 8, which usually represent flat surfaces, but it is of course also curved main surfaces 7, 8 and thus also curved absorber 1 subject of this invention. If the two plates 2, 3 have different sizes, the common connection sbereich 6 is formed in the edge region 5 of the smaller plate. Furthermore, the connecting region 6 can also be at a distance from the actual edges of the plates 2, 3, which can be helpful for assembly purposes.

For the passage of heat transfer fluid, the absorber 1 has at least two openings 9, wherein, depending on the flow direction of the heat transfer fluid, an opening 9 serves as an inlet 10 and a second opening 9 as an outlet 11. Inlet 10 and outlet 11 are preferably arranged diametrically with respect to a center 12 of the absorber 1 and thereby the largest possible part of the absorber volume of heat transfer fluid flows through. The main flow direction is formed by the shortest connection between inlet 10 and outlet 11.

However, it is also an embodiment of the absorber 1 without inlet 10 and outlet 11 possible in which the heat transfer fluid circulates only in the interior of the absorber 1, z. B. when using the absorber 1 as a heat pipe. In this case, only a closable filling opening is required. Furthermore, such an absorber 1 has a heat exchanger which serves as a heat interface for the transfer of heat from the inner circuit of the absorber 1 to an external heat cycle.

The plates 2, 3 consist essentially of metal sheets, but it is also possible that at least parts thereof z. B. are formed by heat-resistant plastic materials.

2 shows a sectional view according to line II-II through the connection region 6 in the edge region 5 of an absorber 1 according to FIG. 1. The two plates 2 and 3 are connected to one another in the connection region 6 in a materially cohesive manner, wherein the connection region 6 consists of a connection section 63 the first plate 2 and a connecting portion 64 of the second plate is composed. As can be seen in Fig. 2, the connecting portion 63 of the first plate 2 is offset relative to the main surface 7 in the direction of the second plate 3, which takes place by a forming process during manufacture. The plates 2 and 3 have outside the connection region 6 between an inner side 13 of the first plate 2 and an inner side 14 of the second plate 3 to each other at a distance 4. As a result, an inner cavity 15 is formed in the absorber 1, which is in operation by a heat transfer gerfluid 16 is flowed through. The heat transfer fluid 16 may for example be formed largely of water, which has a high heat capacity and therefore can transport a high heat content with a low volume flow. In order to prevent freezing of the water at low temperatures, the heat transfer fluid 16 are usually also frost-protective agents added.

The distance 4 between the two plates 2 and 3 is determined by transverse to the major surfaces 7 and 8 of the plates 2 and 3 extending wall parts 17, which holds the two plates 2 and 3 at a distance from each other. In FIG. 2 it can be seen that the wall part 17 is formed from the first plate 2 and the second plate 3 extends substantially even over the connection region 6. As shown in FIG. 2, the second plate 3 is fully supported by a flat base 18, whereby the second plate 3 remains substantially undeformed in the production of the connecting region 6 and thus the connecting portion 64 of the second plate 3 is not offset with respect to its main surface 8 is.

The first plate 2 has in the region of the main surface 7, a first wall thickness 19 and this lies in a range with a lower limit of 0.12 mm and an upper limit of 2.5 mm, for reasons of material savings and better heat transfer a the smallest possible wall thickness 19 is selected, which, however, still provides sufficient mechanical strength of the absorber 1 for normal stresses. The wall thickness of the second plate 3 is also selected from a range with a lower limit of 0.12 mm and an upper limit of 2.5 mm.

In the connection region 6, in which the two plates 2 and 3 are materially interconnected, the total wall thickness 21 composed of the two plates 2 and 3 can be below the sum of the individual wall thicknesses 19 and 20 of the two plates 2 and 3, what with it that at least one of the two plates 2, 3 undergoes an increase in area from the originally undeformed main surface 7 or 8 to form the transverse wall parts 17, which may at least locally be accompanied by a reduction in thickness. As shown in FIG. 2, the wall thickness 19 of the plate 2 slightly increases from the connection region 6 in the direction of its main surface 7 and finds this change in thickness in the illustrated embodiment substantially within the transverse wall portion 17 instead. However, it is also possible that the change in thickness substantially takes place in the transition of the connecting portion 63 in the connecting region 6 in the transverse wall portion 17 or even in the transition of the transverse wall portion 17 in the main surface 7. The distance 4 between the two plates 2 and 3 is obtained as the sum of the bulge heights 22 of the main surfaces 7 and 8 for connection s-area 6 leading wall parts 17. Since in Fig. 2 from the second plate 3 no wall portion 17 is bulged, Since the connecting portion 64 is not offset from the main surface 8, the distance 4 in the embodiment in Fig. 2 corresponds to the bulge height 22 of the wall portion 17, which is formed from the first plate 2. Fig. 2 also shows parts of a device 23 for producing the material connection in the edge region 5 or in the subsequent connection region 6, which comprises an electromagnetic coil assembly 24 which is connected to a source of electrical current pulses, not shown in FIG. 2 and when triggered a current pulse by exerting an electromagnetic impulse force accelerates the originally flat plate 2 against the second plate 3 and thereby produces in a so-called electromagnetic joining process (EMP method) the cohesive connection region 6. To produce the embodiment shown in FIG. 2, the second plate 3 lies with its outer surface 25 on the entire surface on the flat surface 18, while the plate 2 before triggering the current pulse at a short distance, z. B. between 0.5 mm and 3 mm, to the second plate 3 is positioned. When the current pulse is triggered, the region of the plate 2 positioned immediately below the coil arrangement 24, which forms the later connecting section 63 and which is designed to be electrically conductive for carrying out the method, is accelerated toward the second plate 3 with extremely high acceleration, as a result of which the transverse direction extending wall portion 17 is formed and the plate 2 is fixed at a distance 4 to the plate 3.

The two plates 2 and 3 may have the same wall thicknesses 19 and 20, but also as shown in Fig. 2, have different wall thicknesses 19 and 20, wherein in the illustrated embodiment, the wall thickness 20 of the plate 3 is greater than the wall thickness 19 of the plate 2, with its outer side 26 of the solar radiation 27 faces. However, it is also possible to turn in the illustrated embodiment of an absorber 1, the flat plate 3 of the solar radiation 27. The present through the transverse wall portions 17 spatial or three-dimensional shape of the originally flat plate 2 causes a stiffening effect for the entire absorber 1, whereby even with relatively thin wall thicknesses 19, 20 of the finished absorber 1 can have a high mechanical strength.

3 shows a partial cross section through a further embodiment of an absorber 1, in which a connecting region 6 is arranged in the interior of the absorber surface. However, this embodiment of the connection region 6 is also possible in an edge region 5 of such an absorber 1.

As shown in FIG. 3, in this embodiment, wall parts 17 are formed both from the plate 2 and from the second plate 3, which fix the two plates 2 and 3 at a distance 4 from each other starting from the connection region 6. This distance 4 is, as already described above, from the bulge heights 22 of the wall parts 17 together. As shown in Fig. 3, while the absorber 1 may be approximately symmetrical to the joining plane 28 in the connecting region 6, but of course, asymmetric embodiments are conceivable, which lie between the embodiments of Fig. 2 and Fig.3. The illustrated connection region 6 in the interior of an absorber surface causes a stabilization of the distance 4 between the two plates 2 and 3, since with larger surfaces of the absorber 1 by the pressure of the heat transfer fluid 16, the two plates 2 and 3 could be greatly curved apart. In order to protect an absorber 1 over its entire absorber surface against buckling and to keep the two plates 2 and 3 largely flat, it is advantageous if such connection areas are distributed relatively uniformly over the absorber surface and are for example punctiform or have a line shape. The possible bulge occurring due to internal pressurization depends strongly on the distance between adjacent connecting regions 6 and can thereby influence the external shape of an absorber 1 and be actively designed. It may also be a strong bulge desired if the absorber larger clear cross sections for the

Heat transfer fluid 16 should have. The originally flat main surfaces 7, 8 of the plates 2, 3 extend in these embodiments in sections outwardly convex. In Fig. 3 is further shown that the solar radiation 27 facing the outside 26 may have a solar radiation selective coating 29, whereby the efficiency of the absorber 1 can be improved, are reduced in the radiation losses. The coating 29 may be formed, for example, from so-called black-chromium-nickel-pigmented aluminum oxide or so-called sputter layers. These coatings 29 have a high degree of absorption in the wavelength range of the irradiated solar radiation and at the same time a low emissivity in the wavelength range of the thermal radiation emitted by the absorber 1, which is determined by its temperature.

Alternatively, it is also possible to provide a coating 29 having reflective properties, e.g. to redirect solar radiation from the absorber 1 to distant locations.

Furthermore, it is possible that, as also shown in Fig. 3, on the facing inner sides 13 and 14 of the plates 2 and 3 coatings 30 and 31 are mounted from a material different from the plate main material. Thus, for example, an aluminum alloy can be provided as the main plate material, which is provided on the inner sides 13 and 14 of the absorber 1 with a coating 30, 31 of copper, and corrosion phenomena are thereby avoided in conjunction with copper tubes for supplying the absorber 1 with heat transfer fluid 16 , In addition to metallic coatings 30, 31, it is also possible to provide one of the plates 2, 3 on its inner side 13, 14 with a coating 30, 31 made of plastic, whereby likewise a direct contact of the heat transfer fluid is prevented with the plate main material. Such a plastic coating could reduce a heat transfer to the plate 3, which is averted from the solar radiation and thereby reduce heat loss. As shown in FIG. 3, in the connection region 6, such inner coating as well as metal surfaces possibly existing oxide layers due to the extremely high pressures in the joining of the two plates 2 and 3 can be torn open and a direct, metallic contact of the plate main materials are made in the connection area , which ensures the cohesive connection. The embodiment of a connection region 6 shown in FIG. 3 can be produced by acting on the two plates 2, 3 positioned at an exit distance from one another from outside a coil arrangement 24, as already described with reference to FIG. 2, and thereby the plates 2, 3 are joined together in the connection area. The two plates 2 and 3 can be provided before the joining process already with coating materials, such as the coating 29 and / or a coating 30 on the inside, as they affect the joining process not or only insignificantly. In one of the plates 2, 3, the displacement of the connecting portions 63, 64 relative to the respective main surface 7, 8 can also be produced in an upstream forming process prior to the joining process and z. B. the preformed from the second plate 4 connecting portion 64 are supported in the joining operation by a correspondingly shaped pad and the connecting portion 63 are added from the first plate 3 by means of EMPT method.

4 shows a partial cross section through a further embodiment of an absorber 1, in which at least one of the plates 2, 3, in the illustrated embodiment, the plate 2 in the inner cavity 15 of the absorber 1 projecting ribs 32 or projections 33, wherein the projections 33rd represent rather punctiform deformations of the plate 2 and represent ribs 32 rather linear deformation of the plate 2. These ribs 32 or projections 33 are formed by deformation of the plate 2 from the main surface 7 out transversely to this and have transverse to the main surface 7 extending wall portions 34 which approach the second plate 3. In Fig. 4, such a rib 32 and a projection 33 extends approximately to half of the distance 4 between the two plates 2 and 3, but it is also possible that the remaining distance 35 to the second plate 3 is larger or even drops to zero, whereby the rib 32 and the projection 33 may also rest against the second plate 3. However, this is not one of the previously described connection regions 6, since even in the case that the plate 2 touches the second plate 3 in the region of the rib 32 or the projection 33, there is no material connection there. Depending on the height 36, around which a rib 32 or a projection 33 protrudes into the inner cavity 15 of the absorber 1, different effects can be achieved with it. By small heights 36 and in particular a plurality of such projections 33 or ribs 32 can be effected that the heat transfer fluid 16 performs a turbulent flow on the inner side 13 of the absorber 1, whereby the heat transfer from the plate 2 into which the heat transfer fluid 16 is better , than with a pronounced laminar flow on the inside 13th By contrast, larger heights 36 in ribs 32 cause a steering of the flow through the absorber 1, whereby the flow is distributed as uniformly as possible over the entire absorber surface with a suitable design of the ribs 32 to cause possible small temperature differences within the absorber 1. The flow of the heat transfer fluid 16 is directed by such ribs 32 at least approximately in a direction parallel thereto and by the orientation and distribution of such ribs 32, the heat dissipation over the absorber surface can be made uniform.

The described ribs 32 or projections 33 may be formed in particular by a forming process of one of the plates 2, but also by additional attached to the inside, for example glued or welded form elements.

The ribs 32 or projections 33 can be produced economically already in a plate 32 before the production of a connection with a second plate 3.

Forming the ribs 32 or protrusions 33 from the plate 2 can be done, for example, using a die 37 shown in dashed lines, in which the originally flat plate 2 is mechanically plastically deformed. In this case, the deformation can be effected by means of the previously described EMPT method, that is to say under the action of electromagnetic pulse forces which are introduced via a coil arrangement 24, which is also indicated by dashed lines. Alternatively, a deformation by means of a punch-dot stamp shown possible.

In the production of such ribs 32 or projections 33 by means of forming the plate 2 out of the main surface 7, it is possible for the inner side 13 or the outer side 26 to be provided with one of the above-described coatings.

5 shows a view of a rectangular absorber 1, in which ribs 32 projecting into the inner cavity 15 are arranged in the absorber surface. These ribs 32 are arranged similar to ribs of a blade and cause a uniform flow through the absorber 1 with heat transfer fluid 16. The ribs 32 extend differently from the main flow direction 38, which extends substantially from the inlet 10 to the outlet 11 at the absorber 1. The ribs 32 cause no pronounced zones with less Throughflow with Wärmeträgerf uid 16 arise, which would assume a higher temperature by lower heat dissipation and thus the heat losses are increased by radiation. 6 shows a cross section through a solar collector 39, which corresponds in construction to the type of solar collector known from the prior art, but comprises an absorber 1 according to the invention. The absorber 1 is installed in a collector housing 40, wherein, depending on the design of the collector housing 40 of the solar collector 39 are referred to as a frame collector or pan collector. To reduce heat losses via the lower side 41 of the solar collector 39, an insulating element 42 can be arranged between the absorber 1 and the lower side 41 of the solar collector 39, which has the lowest possible heat transfer coefficient and has sufficient temperature and aging resistance. On the side facing the solar radiation 27 side of the absorber 1 is at a distance 43 to the outside 26 of the absorber 1, a solar radiation permeable cover 44 is arranged, which has a very low permeability for emitted from the absorber 1 heat radiation, whereby the solar radiation substantially unhindered until Absorber 1 can get, but heat losses are reduced by heat radiation. The distance 43 can be selected from a range with a lower limit of 1 mm and an upper limit of 50 mm, the smaller distance values with respect to the insulating effect are not so good, but give a low overall height of the solar collector 39 and Such collectors can be integrated particularly well in roof areas. With larger distances 43, the risk increases that form between convection fan 1 and cover 44 convection currents, which can also cause an increase in heat losses. An advantageous value for the distance 43 is therefore about 10 mm.

As an optional feature of a solar collector 39 according to the invention, it is shown in FIG. 6 that the cover element 44 has optical elements 46 on its inner side facing the absorber 1 which have light-directing, light-concentrating or light-scattering properties. The optical elements 46 may have concave or convex surfaces for this purpose and may serve to concentrate the incident solar radiation in the case of concentrating properties on certain zones of the absorber 1 or, in the case of dispersive optical elements, the incident solar radiation in certain zones of the absorber. To reduce sorber surface and mitigate in light-guiding properties also in certain areas and other surface areas. This can be used, for example, to apply portions of the absorber 1, in which a lower heat dissipation is possible, with less solar radiation and in turn redirect it to sections of the absorber 1, in which a better heat absorption and heat dissipation is given.

Furthermore, it is possible that the absorber 1 on its solar radiation 27 facing outside 26 opposite the main surface 7 upstanding projections 47 which have the shape of spherical caps, pyramidal sections, conical sections, cylinder segments or shaft sections. These projections 47 cause convection currents are braked in the interior of the solar collector 39, thereby reducing heat loss to the environment. Furthermore, the protrusions 47 can cause the absorption of solar radiation from certain directions to be improved.

FIG. 7 shows at a corner of an absorber 1 a possible embodiment of an inlet 10, which can serve as an outlet 11 when the throughflow direction 48 is reversed. In this embodiment of an inlet 10, this comprises an opening 9 in the edge region 5 of the absorber 1, which also constitutes a connection region 6, and the cohesive connection between the plates 2 and 3 in the region of the inlet 10 is interrupted. In this embodiment, the heat carrier fluid 16 is introduced approximately in the direction of the joining plane 28 into the inner cavity 15 of the absorber 1. In particular, it is possible in such an inlet 10 in the manufacture of the compound in the edge region 5 to use a pipe socket 49, which can be fixed in position by the connection preparation and can be used for receiving line connections or the like.

8 shows an alternative embodiment of an inlet 10, in which it is not arranged in the edge region 5 of the absorber 1, but is formed by an opening 9 in one of the plates 2 or 3 in the area of the main surface 7 or 8. This embodiment has the advantage that the connecting region 6 in the edge region 5 of the absorber 1 can be produced without interruption and inlets 10 and 11 are subsequently positioned by introducing the corresponding openings 9. FIG. 9 shows a section through the inlet region of an absorber 1 according to the embodiment in FIG. 8, and is the supply of tion of the heat transfer fluid 16 via a connecting piece 50 in the main surface 7 of the plate 2 recognizable.

FIGS. 10 and 11 show a possible embodiment of a device 23 by means of which an absorber 1 according to the invention or such can be produced by means of the method according to the invention, FIG. 10 showing a horizontal view and FIG. 11 a plan view.

The device 23 comprises a plurality of coil arrangements 24, with which different connection regions 6 are produced between two plates 2 and 3, and the absorber 1, as it were, arises stepwise. The plates 2 and 3 are unwound in this embodiment of sheet metal rollers 51 and a first connection station 52 fed, in which the two strip-shaped, superimposed plates 2 and 3 are connected in the edge region 5 to a connecting portion 6. Coil arrays 24 are arranged in the connection station 52, by means of which, by means of an EMPT method, the two plates 2 and 3 are materially connected at their longitudinal edges in accordance with the method described above. The coil assemblies 24 are connected to a power source 53 for generating the electric current pulses line and the connection region 6 is produced stepwise or intermittently.

After the first connection station 52, the two plates 2 and 3 are already connected at their longitudinal edges and are fed to a second connection station 54, in which also by means of a coil assembly 24, a transversely to the transport direction 55 extending connecting portion 6 is prepared, which has a leading edge or trailing edge an absorber element 1 and a later edge region 5 forms. The width 56 of an absorber 1 is limited in this embodiment or in this manufacturing process by the output roller width upwards. However, it is possible that the coil assembly 24 can be approximated to the longitudinal center axis of the plate strips, whereby the width 56 of the absorber can be reduced by this is subsequently trimmed. The length 57 of an absorber 1 results from the distance in which the connecting regions 6 extending transversely to the transport direction 55 are produced by the second connection station 54. As shown in FIGS. 10 and 11, in the second connection station 54, but also in the first connection station 52, additional coil arrangements 24 may be included with which inside The absorber surface additional connecting portions 6 can be made to fix the distance 4 between the plates 2 and 3 at several points. The additional connection areas 6 are shown in FIG. 11 as small circles. After the second connection station 54, the still contiguous absorber elements 1 are separated along a parting line 58 transversely to the transport direction.

FIG. 12 shows a further and possible embodiment of a device 23 for producing an absorber 1. In this case, the device 23 is supplied with two blanks of the plates 2 and 3, and essentially the entire edge region 25 of the two plates 2 and 3 is connected by the coil arrangement 24 to form a connection region 6. In Fig. 12, the coil assembly 24 is in two parts and includes two L-shaped coil assemblies 24. Further, it is possible that between adjacent coil assemblies 24, two pipe sockets 49 are used, which after connection of the later Einlas s 10 and the outlet 11 for form the absorber 1. Inlet 10 and outlet 11 correspond in this embodiment, for example, the embodiment described with reference to FIG. 7.

Characterized in that the coil assemblies 24 extend substantially over the entire edge region 5 of the plates 2 and 3, by means of a single triggering of the current discharge and the force pulse caused thereby the entire edge region 5 of an absorber 1 can be converted to a connection region 6 with material connection.

FIG. 13 shows a possible embodiment of the method for producing an absorber 1, in which a series of overlapping partial connection regions 59, 60, 61, etc., which together form the connection region 6, are produced by means of a coil arrangement 24. It may be possible to convey the plates 2 and 3 through the coil assembly 24 or vice versa to move the device 23 with the coil assembly 24 along the edge region 5 of the plates 2 and 3. After making a partial connection region 59, 60, 61, the plates 2, 3 and the coil assembly 24 are moved relative to each other, whereby a continuous connection region 6 is formed stepwise. Furthermore, it is possible that, as indicated by dashed lines, a second coil arrangement 24 'is provided which is arranged at a distance from the first coil arrangement 24. When both coil assemblies 24, 24 'are activated at the same time, mutually spaced partial connection regions 59 and 61 are produced, that is, a connection region 6 with regular gaps, which in a second process step after displacement of the plates 2, 3 by Further partial connection areas 60,... can be closed and, in this way, a contiguous connection area 6 can again be produced in the edge area 5 of the absorber 1. FIG. 14 shows a further possible embodiment variant for the method for producing an absorber 1 from two plates 2 and 3. Fig. 14 shows the plates 2 and 3 before performing the joining process and with dashed lines the connecting portion 6 after performing the joining process. The plate 3 is supported over its entire surface by a pad 18 and the second plate 2 is positioned in an initial distance 62 to the plate 3. Subsequently, the edge region 5 of the plates 2 and 3 is integrally connected (dashed lines) by the action of a coil arrangement 24 using the EMPT method described above.Through the output distance 62 between the plates 2 and 3, the plate 2 has a sufficient path for acceleration in the direction of the plate 3 and thereby an extremely intimate cohesive connection between the plates 2 and 3 can take place on impact In order to facilitate the mutual positioning before the joining process, it can be provided that on one of the plates 2, 3 or two plates 2, 3 ribs 32 and / or projections 33 are formed, which can be designed so that the optimum for the implementation of the joining process output distance 62 is specified.

In Fig. 15, an embodiment of an absorber 1 is shown in partial section, in which between the plates 2, 3, an intermediate plate 65 is arranged, which extends between two adjacent connecting portions 6 and located between the plates 2, 3 cavity 15 for heat transfer fluid sixteenth divided into two pressure-tightly separated part cavities 66, 67. By this embodiment, two separate flow paths for heat transfer fluid can be formed within the absorber 1. In the illustrated embodiment, the plates 2, 3 are curved convexly outward between the connecting regions, while the intermediate plate 65 extends evenly between the plates 2, 3. The production of this embodiment can be carried out so that the intermediate plate 65 is provided on a flat surface, then the second plate 3 is joined from above with the intermediate plate 65 by means of the previously described methods and after being turned on and laid on one in the connecting regions 6 effective support the second plate 2 is added from above. The main surfaces 7, 8 of the plates 2, 3 can still be flat and parallel to the intermediate plate 65 after joining, as shown by dashed lines, but it is possible, the plates 2, 3 as shown between the connecting portions by internal pressurization - eg in the course of Leak test - convex outward deforming, whereby the clear cross section for receiving or passage of heat transfer fluid 16 can be increased, which can also be carried out in the embodiments described above The embodiments show possible embodiments s variants of the absorber 1, which should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather also various combinations of the individual embodiments are mutually possible and this variation possibility due to the doctrine of technical action by representational invention in the skill of skilled in the art. So are all conceivable embodiments, which are possible by combinations of individual details of the illustrated and described embodiment variant, includes the scope of protection.

For the sake of order, it should finally be pointed out that for a better understanding of the structure of the absorber 1, this or its constituent parts have been shown partially unevenly and / or enlarged and / or reduced in size.

The task underlying the independent inventive solutions can be taken from the description.

Above all, the individual in Figs. 1; 2; 3; 4; 5; 6; 7; 8, 9; 10, 11; 12; 13; 14; 15 show embodiments form the subject of independent solutions according to the invention. The relevant objects and solutions according to the invention can be found in the detailed descriptions of these figures. REFERENCE NUMBERS

Absorber 36 height

Plate 37 die

Plate 38 main flow direction

Distance 39 solar collector

Randbereich 40 Kollektorgehäu se

Connection area 41 bottom

Main area 42 insulating element

Main area 43 distance

Opening 44 cover

Inlet 45 inside

Outlet 46 optical element

Middle 47 projection

Inside 48 flow direction

Inside 49 pipe sockets

Cavity 50 connecting pieces

Heat transfer fluid 51 sheet roll

Wall section 52 connection station

Pad 53 Power source

Wall thickness 54 connection s station

Wall thickness 55 Tran Sportrichtung

Total wall thickness 56 width

Buckling height 57 length

Device 58 dividing line

Coil arrangement 59 partial connection area

Outside 60 part connection area

Outside 61 Part connection area

Solar radiation 62 output distance

Joining plane 63 Connecting section

Coating 64 connecting section

Coating 65 intermediate plate

Coating 66 partial cavity

Rib 67 partial cavity

head Start

wall section

distance

Claims

Patent claims

1. Flat absorber (1) for solar radiation with at least two spaced (4) from each other plates (2, 3), at least in its edge region (5) a den- th coherent connection region (6) form, in the connecting portions (63, 64) of the plates (2, 3) are interconnected, and the transverse to main surfaces (7, 8) of the plates (2, 3) extending wall parts (17) for distancing the two major surfaces (7, 8) of Plates (2, 3) are connected, characterized in that on at least one plate (2,3) of the connecting portion (63) by a direction in the direction of the other plate (3, 2) oriented te conversion relative to the main surface (7, 8 ) of the first plate (2, 3) is offset and that the transverse wall parts (17) from at least one of the plates (2, 3) are integrally formed.

2. absorber (1) according to claim 1, characterized in that the wall thickness (19) of at least one of the two plates (2) from the connecting region (6) in the direction of her

Main surface (7, 8) increases.

3. absorber (1) according to claim 1 or 2, characterized in that the absorber (1) in the absorber surface within the edge region (5) additional Verbindungsberei- che (6).

4. absorber (1) according to one of claims 1 to 3, characterized in that the additional connection areas (6) occupy a surface portion of at least 50% of the absorber berberfläche within the edge region (5).

5. absorber (1) according to any one of the preceding claims, characterized in that between the connecting regions (6) lying cavities (15) form a net-like, serpentine or harp-like structure within the absorber surface.

6. absorber (1) according to one of claims 1 to 5, characterized in that the cohesive connection in the connecting regions (6) is made by an EMPT process.

7. absorber (1) according to any one of the preceding claims, characterized in that at least one of the plates (2, 3) of the main surface (7, 8) in the inner cavity (15) of the absorber (1) projecting ribs (32) has, in particular deviating from the main flow direction (38) of the absorber (1) extend, preferably arranged as leaf ribs.

8. absorber (1) according to any one of the preceding claims, characterized in that at least one of the plates (2, 3) of the main surface (7, 8) in the inner cavity (15) of the absorber (1) projecting projections (33) , In particular in the form of spherical caps, pyramidal sections, conical sections, cylinder segments, shaft sections.

9. absorber (1) according to claim 7 or 8, characterized in that the ribs (32) and / or projections (33) in one piece by deforming a plate (2, 3) from the main surface (7, 8) made out are.

10. absorber (1) according to claim 9, characterized in that the ribs (32) and / or projections (33) from a plate (2, 3) are made by an EMPT method.

11. absorber (1) according to any one of the preceding claims, marked thereby, that the connecting regions (6) at least one usable as a heat pipe closed, in particular elongated, cavity (15) between the plates (2, 3) limit.

12. An absorber (1) according to any one of claims 1 to 10, characterized in that at least one inlet (10) or at least one outlet (11) for heat transfer fluid (16) by a parallel to the main surfaces (7, 8) of the plates ( 2, 3) extending opening (9) in the edge region (5) is formed.

13. An absorber (1) according to any one of claims 1 to 10 or claim 12, characterized in that at least one inlet (10) or at least one outlet (11) for heat transfer fluid (16) through an opening (9) in a main surface ( 7, 8) of one of the plates (2, 3) is formed.

14 absorber (1) according to claim 12 or 13, characterized in that inlet

(10) and outlet (11) at the edge region (5) are arranged substantially diametrically with respect to the center (12) of the absorber (1).

15. An absorber (1) according to any one of the preceding claims, characterized in that at least one of the plates (2, 3) on one of the other plate (3, 2) facing inner surface (13, 14) has a coating (30, 31) having a different material to their plate main material, in particular of plastic and / or metal.

16. An absorber (1) according to any one of the preceding claims, characterized in that at least one of the plates (2, 3) on a side facing away from the other plate (3, 2) outside (26) for solar radiation selective or reflective coating ( 29).

17. An absorber (1) according to any one of the preceding claims, characterized in that one of the plates (2, 3) facing away from the other plate (3, 2) outside (26) opposite the main surface (7, 8) towering projecting Projections (47), in particular in the form of spherical caps, pyramidal sections, conical sections, cylinder segments or shaft sections.

18. An absorber (1) according to any one of the preceding claims, characterized in that the plates (2, 3) are made of different main materials, in particular one of the two plates (2, 3) preferably made of aluminum material or copper material and the other of the both plates (3, 2) preferably made of stainless steel or coated steel sheet.

19. An absorber (1) according to any one of the preceding claims, characterized in that bulge heights (22) of the main surfaces (7, 8) of the two plates (2, 3) arched wall parts (17) are different in size.

20. An absorber (1) according to any one of the preceding claims, characterized in that on one of the plates (2, 3) of the connecting portion (63, 64) substantially without offset to the main surface (7, 8) of the plate (2, 3) runs.

21 absorber (1) according to any one of the preceding claims, characterized in that the distance (4) between the two plates (2, 3) from a range with a lower limit of 1 mm, preferably 2 mm, in particular 3 mm and a upper limit of 30 mm, preferably 10 mm, in particular 6 mm is selected.

22 absorber (1) according to any one of the preceding claims, characterized in that the plates (2, 3) between adjacent connecting portions (6) are convexly curved outwardly.

23. An absorber (1) according to any one of the preceding claims, characterized in that the wall thicknesses (19, 20) of the two plates (2, 3) from a range with a lower limit of 0.12 mm and an upper limit of 2, 5 mm is selected.

24. An absorber (1) according to any one of the preceding claims, characterized in that between the plates (2, 3) an intermediate plate (65) is arranged, which extends between two adjacent connecting portions (6) and one between the plates (2). 2, 3) located cavity (15) for heat transfer fluid (16) in two pressure-tightly separated part cavities (66, 67) divided.

25 solar collector (39) with a flat absorber (1) and a distance

(43) arranged by the absorber (1) for solar radiation permeable cover member (44), characterized in that the planar absorber (1) is designed according to one of the claims 1 to 24.

26. Solar collector (39) according to claim 25, characterized in that the distance (43) between the outer side (26) of the absorber (1) and the cover (44) from a range with a lower limit of 1 mm, preferably 2 mm , in particular 5 mm and an upper limit of 50 mm, preferably 30 mm, in particular 15 mm is selected.

27. Solar collector (39) according to claim 25 or 26, characterized in that the cover element (44) is formed from one or more glass layers or one or more plastic layers or a combination or mixed sequence of such.

28 has solar collector (39) according to one of claims 25 to 27, characterized in that the cover (44) on an absorber (1) facing the inside (45) light-directing or concentrating or scattering optical elements (46).

29. A method for producing a planar absorber (1) for solar radiation from two plates (2, 3) which are positioned one above the other with their mutually facing surfaces (13, 14), whereupon at the two plates (2, 3) in their Edge region (5) a cohesive connection region (6), in the connecting portions (63, 64) of the plates (2, 3) are interconnected, is produced, characterized in that on at least one plate (2) opposite to the main surface (7 ) offset connecting portion (63) is produced by a directed towards the other plate (3) deformation and thereby transverse to main surfaces (7, 8) of the plates (2, 3) extending wall parts (17) of at least one of the plates (2, 3) are integrally formed.

30. The method according to claim 29, characterized in that the cohesive

Connection of the plates (2, 3) by an electromagnetic joining process (EMPT) takes place.

31. The method according to claim 29 or 30, characterized in that the plates (2, 3) immediately before performing the electromagnetic joining process (EMPT) to each other so positioned that between facing inner sides (13, 14) of the plates (2 , 3) an initial distance (62), in particular between 0.5 mm and 3 mm.

32. The method according to claim 31, characterized in that the starting distance (62) between the plates (2, 3) is produced by ribs (32) and / or projections (33) on at least one of the inner sides (13, 14) ,

33. The method according to any one of claims 29 to 32, characterized in that on at least one of the plates (2, 3) on one of the other plate (3, 2) facing the inside (13, 14) prior to the production of the material connection region (6 ) a coating layer (30, 31) made of a different material to the plate main material, in particular of plastic and / or metal is applied.

34. The method according to any one of claims 29 to 33, characterized in that on one of the plates (2, 3) on a side facing away from the other plate (3, 2) Außenoberflä- (26) before the production of the material connection region (6 ) a selective coating (29) of a solar radiation selective coating material is applied.

35. The method according to any one of claims 29 to 34, characterized in that a linear cohesive connection region (6) by a series of overlapping partial connection regions (59, 60, 61, ...) is formed, which are at least partially produced in temporal succession ,

36. Device (23) for producing a planar absorber (1), in particular according to one of claims 1 to 24 and / or according to a method according to one of claims 29 to 35, of two plates (2, 3) with spaced apart and each other facing inner sides (13, 14) and one of the plates (2, 3) formed cohesive connection region (6), characterized in that the device (23) connectable to a current source (53) for electrical current pulses electromagnetic coil assembly (24 ) which, when a current pulse is triggered by exerting an electromagnetic impulse force in the connection region (6), accelerates one of the plates (2) against the other plate (3) and thereby the integral connection region (6) and transversely to the main surfaces (7, 8) the plates (2, 3) extending wall parts (17) produces.

37. Device (23) according to claim 36, characterized in that the coil arrangement (24) extends in one or more parts essentially over the entire edge region (5) of the absorber (1) to be produced.

38. Use of a device according to claim 36 or 37 for producing a planar absorber (1) according to one of claims 1 to 24 or for carrying out a method according to one of claims 29 to 35.