Solar-thermal module

Abstract

The invention relates to a solar-thermal module as part of a solar-thermal receiver with a high level of thermal efficiency for the absorption of solar radiation for heating a heat carrier medium flowing inside each solar-thermal module. The invention also relates to a solar-thermal receiver comprising the solar-thermal modules according to the invention. The invention further relates to a method for using the solar-thermal receiver.

Description

[0001] Description

[0002] Solar thermal module

[0003] The present invention relates to a solar thermal module for absorbing concentrated solar radiation to heat a heat transfer medium flowing inside the module. Furthermore, the present invention relates to a solar thermal receiver comprising the solar thermal modules according to the invention. Furthermore, the present invention relates to a method for using the solar thermal receiver.

[0004] Solar thermal energy is fundamentally a well-known field, and solutions for efficiently harvesting energy from solar radiation have been discussed for many years. Nevertheless, practical problems challenge the widespread application of solar thermal tower systems, for example. Such solar thermal tower systems comprise a tower, a solar thermal receiver located at the top of the tower, which heats a heat transfer medium, and a plurality of heliostats arranged on the ground. These heliostats are aligned so that their mirrors reflect solar radiation to the receiver. In the receiver, the concentrated solar radiation is converted into heat and transferred to the heat transfer medium. The heated heat transfer medium is then fed to a suitable heat consumer or heat storage system for later use.

[0005] For example, patent specification EP 2 520 872 B1 discloses, particularly in Figure 4 thereof, a solar thermal module which is intended to be used as a solar thermal receiver comprising several solar thermal modules similar to EP 2 520 872 B1, Figure 2, in corresponding systems similar to EP 2 520 872 B1, Figure 1. Due to the special shape of the outer surface with elevations and depressions, such receivers promise a higher level of efficiency than conventional receivers for heating a heat transfer medium with a smooth outer surface. The cold heat transfer medium is directed inside such a special solar thermal module directly to its respective elevation, thereby cooling it particularly effectively. The heat transfer medium then flows inside the module towards the depressions in the outer surface, is further heated in the process, and finally leaves the respective solar thermal module.On the outer surfaces of the elevations, unabsorbed solar heat is not completely radiated into the environment and would thus be lost, but radiates partly onto the adjacent elevations, so that part of this heat can also be absorbed and dissipated by the heat transfer medium.

[0006] In practice, however, it turns out that such solar thermal modules are not being used because many details of their technical implementation remain unresolved. These include, for example, compensating for thermal expansion while maintaining the mechanical stability of the modules, appropriate sealing of the flow paths, and sufficient cooling of all thermally stressed components.

[0007] Therefore, there is still a problem in heating the heat transfer medium with a suitable solar thermal module similar to EP 2 520 872 B1, Figure 4, in such a way that a particularly high level of efficiency is achieved due to the special shape of the outer surface of a solar thermal receiver constructed from several modules similar to EP 2 520 872 B1, Figure 2. This special shape of the outer surface, which is necessary for high efficiency, includes the property that the cold heat transfer medium should cool the front tip of the solar thermal module on its inside and then flow out to the rear as it is further heated. For this to happen, the inflowing cold heat transfer medium must necessarily pass through the flow area of ​​the hot outflowing heat transfer medium.In particular, the hot and cold zones of the solar thermal module must be sufficiently insulated from each other, thermal expansion must be adequately compensated, and the receiver must be sufficiently mechanically resilient and sufficiently sealed. Large temperature differences exist within the solar thermal module, as its exterior is exposed to highly concentrated solar radiation, while the inflowing heat transfer medium has a low temperature and the outflowing medium has a high temperature.

[0008] These and other problems are solved by the devices and methods described below. Further advantageous embodiments can be found in the dependent claims and the detailed description. These advantages can be used to adapt a solution to specific needs or to solve further problems.

[0009] According to one aspect, the present invention relates to a solar thermal module suitable for use as a component of a solar thermal receiver for the absorption of solar radiation for heating a heat transfer medium flowing inside the solar thermal module, having the following features: the solar thermal module has an absorption region for solar radiation, the absorption region has an outer surface, the outer surface of the absorption region being substantially convex in the form of a cap, the absorption region being impermeable to solar radiation, the solar thermal module being suitable for being connected to a heat transfer medium supply channel from which the heat transfer medium enters the solar thermal module, the solar thermal module being adapted so that the supplied heat transfer medium flows through the solar thermal module through at least one inner tube,wherein the heat transfer medium is first guided to the tip of the absorption region inside the solar thermal module, wherein the heat transfer medium is guided from the tip of the absorption region inside the solar thermal module along the remaining absorption region, wherein the solar thermal module is adapted such that the heat transfer medium exits through an outlet into a heat transfer medium discharge channel, wherein the at least one inner tube comprises an inner tube A, wherein a portion of the inner tube A is adapted to extend through the heat transfer medium discharge channel, wherein the portion of the inner tube A is enclosed by an outer tube, wherein the outer tube is adapted to form part of the wall of the heat transfer medium discharge channel, wherein the solar thermal module has at least one spring element in the force flow between the inner tube A and the outer tube,wherein the at least one spring element is adapted to compensate for a different thermal expansion of the inner tube A and the outer tube, wherein the at least one spring element has a spring force which is transmitted in the inner tube A as a tensile force and in the outer tube as a compressive force.

[0010] It has been observed that such a design of the solar thermal module enables a significant minimization of thermal stresses. Furthermore, it has been determined that the solar thermal modules according to the invention provide a higher thermal efficiency. The solar thermal modules according to the invention are particularly effective in absorbing focused solar radiation. Such focused solar radiation is provided, for example, by the use of heliostats, whereby solar radiation from large areas can be concentrated by solar thermal receivers onto the solar thermal modules according to the invention.

[0011] The term "absorption area" in the sense of the present invention refers to the area of ​​the solar thermal module which is adapted to be heated on its outside by solar radiation and cooled on its inside by the heat transfer medium.

[0012] The term "tip of the absorption region" in the sense of the present invention refers to the end of the solar thermal module which is opposite the inflow end of the solar thermal module, which is adapted so that the heat transfer medium flows into the solar thermal module through the inflow end.

[0013] The term "substantially convex outer surface of the absorption region" in the sense of the present invention means that the outer surface of the absorption region of the solar thermal module has a substantially convex shape. Preferably, only the connecting regions of the adjacently arranged absorption regions have non-convex components.

[0014] According to a further aspect, the present invention relates to a solar thermal receiver comprising a plurality of solar thermal modules according to the invention, a heat transfer medium supply channel and a heat transfer medium discharge channel, wherein the heat transfer medium supply channel is connected to the plurality of solar thermal modules, wherein a part of the heat transfer medium discharge channel is formed by an outer tube of the plurality of solar thermal modules.

[0015] According to a further aspect, the present invention relates to a method for obtaining thermal energy from solar radiation, wherein solar radiation is absorbed by means of a large number of solar thermal modules according to the invention and the heat thereof is transferred into a heat transfer medium, wherein the heat transfer medium is guided from the large number of solar thermal modules into a heat transfer medium discharge channel, wherein the heat transfer medium is guided from the heat transfer medium discharge channel into at least one heat consumer and / or into at least one heat accumulator, wherein the heat transfer medium is guided from the at least one heat consumer and / or the at least one heat accumulator into the heat transfer medium supply channel, wherein the heat transfer medium is guided from the heat transfer medium supply channel again into the large number of solar thermal modules.

[0016] To facilitate understanding of the invention, reference is made to the following detailed description and the attached figures. It should be understood that the following details of the embodiments are not to be construed as limitations of the present invention. Instead, they represent preferred embodiments with particular advantages that may serve to better understand the present invention.

[0017] Fig. 1 shows a schematic view of a solar thermal tower system.

[0018] Fig. 2 shows a sectional view through a single solar thermal module according to an embodiment of the present invention.

[0019] Fig. 3 shows a partial view of the vertical support structure of the solar thermal module with webs and bays according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module according to the invention shown in Fig. 2.

[0020] Fig. 4 shows a partial view of the anti-twist device for a screw head according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module shown in Figure 2. According to one aspect, the present invention relates to a solar thermal module as described above.

[0021] According to further embodiments, it is preferred that the solar thermal module comprises a base plate B and a guide B, wherein the base plate B and the guide B are suitable for forming lateral boundaries of the heat transfer medium discharge channel, wherein the guide B is connected to a base plate C, wherein the solar thermal module in each case has an articulated connection on a support surface between the base plate B and an outer pipe and on a support surface between the guide B and the outer pipe. It has been found that with such embodiments of the solar thermal module according to the invention, a vertical height offset in the heat transfer medium discharge channel between its rear wall as base plate B and its front wall as base plate C and the guide B connected thereto in the region of the outer pipe leading through can be compensated for very effectively.The term "articulated connection" in the sense of the present invention is to be understood as a movable connection between at least two rigid bodies.

[0022] According to further embodiments, it is preferred that the solar thermal module has a vertical and horizontal inner support structure on the side illuminated by the solar radiation, wherein the inner support structure consists of a base plate C and a guide B and a flange screwed to it, wherein the base plate C is mechanically decoupled from the guide B and the flange in that several webs of the base plate C distributed over the circumference are guided in indentations of the guide B. It has been found that for typical applications, noticeable mechanical stresses can build up in the solar thermal module.However, due to the structure described above, it is possible that even with very high temperature differences between the inner area of ​​the support structure of the solar thermal module, which is not illuminated by solar radiation, and the outer area of ​​the support structure of the solar thermal module, which is illuminated by solar radiation, only low mechanical stresses build up in the solar thermal module.

[0023] According to further embodiments, it is preferred that the connection between the heat transfer medium supply channel and the inside of the tip of the absorption region consists of at least two pipes, wherein the at least two pipes are connected to each other in an articulated manner. For example, in embodiments in which the attachment of the inner pipe B to the inside of the tip of the absorption region is designed in a more delicate manner, it has been observed that this design results in improved mechanical reliability of the solar thermal module.

[0024] According to further embodiments, it is preferred that a base plate A, an inner tube A and an inner tube B, preferably all components which are adapted to guide the heat transfer medium in the interior of the solar thermal module to the tip of the absorption region, are made of metallic materials, and wherein a cap with cooling elements, a guide A, a flange, a base plate C with cooling elements, a guide B, an outer tube and a base plate B, preferably all components which are adapted to guide the heat transfer medium in the interior of the solar thermal module away from the tip of the absorption region, are made of ceramic materials. Such a structure has proven advantageous in order to minimize the mechanical stresses occurring as a result of the specific structure. The aforementioned material combination allows the thermal stresses to be kept low during operation of the solar thermal module in a very simple manner.

[0025] Furthermore, it has proven advantageous for typical applications if the inner tube B consists of at least one ceramic material. According to further embodiments, it is preferred that a base plate A and an inner tube A, preferably all components which are adapted to conduct the heat transfer medium in the interior of the solar thermal module up to the direction of the tip of the absorption region, consist of metallic materials and wherein an inner tube B, a cap with cooling elements, a guide A, a flange, a base plate C with cooling elements, a guide B, an outer tube and a base plate B, preferably all components which are adapted to conduct the heat transfer medium in the interior of the solar thermal module up to the tip of the absorption region and then away from the tip of the absorption region, consist of ceramic materials.Such a design has proven advantageous for minimizing the mechanical stresses that occur as a result of the specific construction while simultaneously providing increased resistance to thermal stress at this specific location. This provides a particularly advantageous design for applications subject to high thermal and mechanical stress.

[0026] According to further embodiments, it is preferred that a plurality of cooling elements are located on a base plate C, wherein the cooling elements are each adjacent to a guide B at a small distance, wherein the base plate C and the guide B form a flow channel for the heat transfer medium, wherein the solar thermal module has a flow channel for the heat transfer medium, wherein the surfaces of the base plate C and the guide B are geometrically designed such that the remaining free cross-sectional area of ​​the flow channel continuously decreases in the flow direction.The term "close clearance" as used above means that the tips of the cooling elements reach close to the surface of guide B facing them, preferably as close as possible, but still maintain a sufficiently large distance so that they do not touch the guide B at the maximum possible thermal expansion, without causing unacceptably high compressive forces on the cooling elements. The maximum possible thermal expansion results from the maximum possible temperature differences between the base plate C, the cooling elements, and the guide B.

[0027] According to further embodiments, it is preferred that screw connections are distributed around the circumference inside the solar thermal module, each comprising a screw and a nut, wherein the screw has a head, wherein the head of the screw is provided with at least one indentation in the longitudinal direction, preferably with indentations running all the way around, wherein a retaining recess is provided next to the head of the screw, for example on the flange, and wherein the at least one indentation and the retaining recess are suitable for receiving a locking pin. It has thus been observed that a further improvement in the design of the solar thermal module according to the invention can be achieved by means of such a locking option. Typically, it is preferred that the solar thermal module also comprises the locking pin on the screw arranged in the interior. In such embodiments, the screw connections also comprise a safety pin.Such a locking pin provides a simple and reliable way to prevent the screw from turning accidentally.

[0028] According to further embodiments, it is preferred that the solar thermal module has a base plate C, wherein the base plate C has at least one fastening for adjacent solar thermal modules, wherein the at least one fastening is adapted such that the heat transfer medium is guided under the at least one fastening before the heat transfer medium leaves the solar thermal module. Although the heat transfer medium already has a very high temperature at this point during use, it has been found that the cooling effect achievable hereby is very advantageous in typical applications. In particular, in the case of very strongly focused, intense solar radiation, the fastenings of the adjacent solar thermal modules can become very hot, so that the aforementioned cooling further increases the area of ​​application without any noticeable additional effort.

[0029] According to further embodiments, it is preferred that the solar thermal module comprises a flange, an inner tube B, a guide A, and a cap, wherein the inner tube B, the guide A, and the cap are each attached to the flange by means of bayonet locks. Attaching the inner tube B, the guide A, and the cap to the flange by means of a bayonet lock requires a relatively complex solar thermal module structure. However, it has been shown that, in addition to the reliable attachment of the components, a particularly space-saving design is also possible in this way.

[0030] According to a further aspect, the present invention relates to a solar thermal receiver as described above.

[0031] According to a further aspect, the present invention relates to a method as described above.

[0032] According to further embodiments, it is preferred that the heat transfer medium is directed to at least one heat consumer, wherein the at least one heat consumer comprises at least one heat exchanger. Preferably, the at least one heat exchanger is a steam boiler and / or a preheater of a steam boiler. For example, such steam boilers and preheaters can be used in steam turbines. It has been found that this allows for very efficient utilization of renewable energy for industrial applications, such as steam turbines in particular.

[0033] Figure 1 shows a schematic view of a solar thermal tower system 1. The solar thermal tower system 1 in the present case comprises a heat transfer medium circuit 2 through which a heat transfer medium, in this case gaseous, for example air, is passed. Integrated into the heat transfer medium circuit 2 are a compressor 3 which compresses the heat transfer medium, a solar thermal receiver 4 according to an embodiment of the present invention, which is supplied with the heat transfer medium compressed by the compressor 3 via a heat transfer medium supply channel 5, for example in the form of a pipeline, a heat transfer medium discharge channel 6, for example in the form of a pipeline, a heat consumer 8, for example in the form of a waste heat steam generator, and optionally a heat storage device 7, which can be designed as a solid-state heat storage device.From the heat consumer 8 and the heat accumulator 7, the heat transfer medium can then be fed back to the compressor 3 via a further connecting line 9, provided that the heat transfer medium circuit 2 is closed at this point.

[0034] The solar thermal tower system 1 further comprises a tower 10, in the upper region of which the solar thermal receiver 4 is arranged, and a plurality of heliostats 12 arranged on the ground 11, which are positioned in a ring or ring segment-like manner around the tower 10. The heliostats 12 are arranged and aligned such that they reflect the solar radiation 13 and thus concentrate it as concentrated solar radiation 14 onto the solar thermal receiver 4. For this purpose, the heliostats 12 are motor-driven to track the sun in at least two axes.

[0035] During operation of the solar thermal tower system 1, the gaseous heat transfer medium is compressed using the compressor 3 and fed to the solar thermal receiver 4 via the heat transfer medium supply channel 5. The heliostats 12 bundle and concentrate the solar radiation 14 onto the solar thermal receiver 4, through which the heat transfer medium flows. The heat transfer medium is heated to temperatures in the range of several hundred degrees Celsius. The heated heat transfer medium is then fed via the heat transfer medium discharge channel 6 towards the heat consumer 8 or towards the heat storage unit 7, where the heat transfer medium releases its heat and is cooled accordingly. The cooled heat transfer medium can then be fed back to the solar thermal receiver 4 via the connecting line 9 and the heat transfer medium supply channel 5, provided the circuit between the heat consumer 8, the heat storage unit 7 and the compressor 3 is closed.

[0036] Figure 2 shows a portion of the solar thermal receiver 4 illustrated in Figure 1, comprising a solar thermal module 15 according to the invention. A solar thermal receiver 4 comprises a plurality of virtually identical solar thermal modules 15 connected in parallel. Base plate A 31, base plate B 33, and base plate C 37 are each aligned vertically so that the absorption region 30 faces the solar radiation 14 reflected from the ground at a suitable angle. Viewed from the direction of the solar radiation 14, the absorption region 30 of the solar thermal module 15 is convex in its center and concave at its edges.

[0037] A solar thermal module 15 each comprises a channel-shaped continuation of the heat transfer medium supply channel 5 and the heat transfer medium discharge channel 6 inside the solar thermal receiver 4 formed from many modules 15. The base plate A 31 forms the outer side of the continuation of the heat transfer medium supply channel 5. The inner side of this heat transfer medium supply channel 5 is omitted in the solar thermal receiver 4 if it is completely cylindrical, or it is not shown in Figure 2 for a not completely cylindrical design, as it is irrelevant for the illustration of the invention. The base plate B 33 and the base plate C 37 form the side walls of the heat transfer medium discharge channel 6 inside the solar thermal receiver 4, which becomes an annular channel in a completely cylindrical design and forms a ring segment in a not completely cylindrical design.The cold heat transfer medium enters the inner tube A 48 of each individual solar thermal module 15 from the heat transfer medium supply channel 5, then flows through the inner tube B 47 and is thus guided to the inside of the tip of the absorption region 30. The outside of the absorption region 30 consists of the cap 44 and the base plate C 37, both of which are strongly heated by the concentrated solar radiation 14 and transfer the absorbed heat to the heat transfer medium flowing along their inner sides.For this purpose, the cap 44 has on its inside a plurality of cooling elements 45 which are closely spaced from the guide A 46 and from the outside of the flange 40, while the base plate C 37 has on its inside a plurality of cooling elements 38 which are closely spaced from the guide B 36 and which together form the flow channel of an individual module 15 for heating the heat transfer medium. The heated heat transfer medium exits through a circumferential gap between the base plate C 37 and the guide B 36, whereby it reaches the common heat transfer medium discharge channel 6 of all solar thermal modules 15 connected in parallel.

[0038] For mechanical fastening, the inner tube A 48 is connected on its inlet side to a retaining nut 52 which preloads a spring element 51. The compressive force of the spring element 51 is transmitted to the base plate A 31 via the sleeve 50. At the same time, the spring element 51 exerts a tensile force on the inner tube A 48 via the retaining nut 52. At the outlet side of the inner tube A 48, a collar located thereon transmits a corresponding compressive force into the outer tube 49. This compressive force is introduced from the outer tube 49 with a collar located thereon via an articulated support surface 34 into the base plate B 33, which is supported on the base plate A 31 via spacers 32. The force flow generated by the preloaded spring element 51 is thus closed.This makes different thermal expansions of the inner pipe A 48 and the outer pipe 49 possible without the mechanical cohesion of these two and the other components mentioned being lost.

[0039] The outer tube 49, held in place by the spring force of the spring element 51, also has a collar on its side facing the absorption area 30, which collar can move articulately in the support surface 35 of the guide B 36. The articulated connection of the outer tube 49 to the base plate C 37 and to the other components in the absorption area 30 is achieved by the guide B 36 and the flange 40 enclosing the aforementioned collar of the outer tube 49. The guide B 36 and the flange 40 are pulled together by several screw connections distributed around the circumference, each consisting of a screw 41 and a nut 39, so that they enclose the aforementioned collar of the outer tube 49. The articulated support surfaces 34 and 35 enable a vertical height offset of the two side walls of the heat transfer medium discharge channel 6.

[0040] The head of screw 41 is positively secured against rotation by means of locking pin 42. A cover 43 located on the inner tube B 47 holds this locking pin 42 in position and thus prevents it from accidentally falling out. The nut 39 is also positively secured against rotation in its respective retaining recess of the guide B 36.

[0041] The inner tube B 47, the guide A 46 and the cap 44 are each attached to the flange 40 by means of bayonet locks.

[0042] During operation, the heat transfer medium is passed from the relatively cold heat transfer medium supply channel 5 through the inner pipe A 48 and thus through the hot heat transfer medium discharge channel 6, in order to cool the absorption area 30 after flowing through the inner pipe B 47. This cooling effect would be significantly reduced if the heat transfer medium were already heated up significantly as it flowed through the inner pipe A 48 through the heat transfer medium discharge channel 6. Therefore, this feedthrough is formed in a double-shell design with the inner pipe A 48 and the outer pipe 49, which improves the efficiency of the solar thermal module 15.

[0043] It has been shown that for the inventive construction of the solar thermal modules 15, it is typically advantageous to take the thermal expansion of the materials into account. During operation, different temperatures arise in the components through which the cold heat transfer medium flows compared to the components around which the hot heat transfer medium flows. While metallic materials exhibit high thermal expansion, the thermal expansion of ceramic materials is low. Therefore, if metallic materials are subjected to a small temperature change and ceramic materials to a large temperature change, similar absolute thermal expansions result for the metallic and ceramic components, which enables a design with overall lower thermal stresses. Against this background, the base plate A 31, the inner tube A 48, and the inner tube B 47, in particular, are made of metallic materials.Alternatively, the inner tube B 47 is made of at least one ceramic material, which is typically advantageous for many applications due to its higher thermal resistance. Additionally made of ceramic materials are, in particular, the cap 44 with the cooling elements 45, the guide A 46, the flange 40, the base plate C 37 with the cooling elements 38, the guide B 36, the outer tube 49, and the base plate B 33.

[0044] Nevertheless, during operation of the solar thermal module 15, different thermal expansions of the various components remain. The greatest changes in length can occur between the cold inner pipe A 48 and the hot outer pipe 49. The spring element 51 compensates for such different changes in length without the cohesion of the solar thermal module 15 being lost. If several solar thermal modules 15 are stacked on top of one another, different vertical displacements of the hot base plate B 33 and the significantly hotter base plate C 37, which is heated directly by the solar radiation 14. Due to the articulated support surfaces 34 and 35, a vertical offset of the two base plates 33 and 37 is possible during operation of the system without unacceptably high thermal stresses occurring in the connecting outer pipe 49.

[0045] Although a vertical offset of the two base plates 33 and 37 is permitted, this must not result in any leverage that could have a destructive effect on the delicate transition from the inner pipe B 47 to the guide A 46. Therefore, the supply of the cold heat transfer medium from the heat transfer medium supply channel 5 to the entry into the interior of the cap 44 is essentially carried out using two separate components, namely the inner pipe A 48 and the inner pipe B 47. The connection between these two inner pipes is made movable by the respective connection to the outer pipe 49 and to the flange 40, because the outer pipe 49 is movably mounted between the guide B 36 and the flange 40.

[0046] Figure 3 shows a partial view of the vertical support structure of the solar thermal module 15 with webs and bays according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module according to the invention shown in Figure 2. On the inside of the base plate C 37 there are several webs 70 distributed over the circumference, which project into indentations 71 of the guide B 36 and are each supported there by means of a seal 73. For illustration, Figure 3 shows four webs 70 on the right without the seals 73 and four webs 70 with the seals 73 on the left. The holes 72 serve as a passage for the screw connection shown in Figure 2, each consisting of screw 41 and nut 39, with the aid of which the webs 70 are enclosed by the guide B 36 and the flange 40 and thus held in position.

[0047] During operation of the solar thermal module 15, the outer base plate C 37 has a significantly higher temperature than the inner guide B 36 and the flange 40. Due to the mechanical decoupling shown in Figure 3, the base plate C 37 can expand more freely than the guide B 36 and the flange 40 without the required mechanical connection between these three components being lost in the axial direction.

[0048] By separating the vertical and horizontal support structure on the side of the solar thermal module 15 facing the solar radiation 14 into the base plate C 37 and the components guide B 36 and flange 40 which are screwed together, greatly differing temperatures do not lead to inadmissibly high thermal stresses in the radial direction, while the support function in the axial direction remains intact.

[0049] Figure 4 shows a partial view of the anti-twist device for a screw head according to advantageous embodiments of the present invention, as is also integrated, for example, in the solar thermal module shown in Figure 2. The head of the screw 41 is provided with indentations 91 running all the way around in the longitudinal direction. Next to the head of the screw 41, there is a retaining recess 90 on the flange 40. The positive anti-twist device for the screw 41 is achieved by inserting a locking pin 42 into the retaining recess 90 and, at the same time, into an indentation 91 on the head of the screw 41.

[0050] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. A solar thermal module (15) suitable for use as a component of a solar thermal receiver (4) for absorbing solar radiation (14) for heating a heat transfer medium flowing inside the solar thermal module (15), having the following features: the solar thermal module (15) has an absorption region (30) for solar radiation (14), the absorption region (30) having an outer surface, the outer surface of the absorption region (30) being substantially convex in the form of a cap (44), the absorption region (30) being impermeable to solar radiation (14), the solar thermal module (15) being suitable for being connected to a heat transfer medium supply channel (5) from which the heat transfer medium enters the solar thermal module (15), the solar thermal module (15) being adapted such that the supplied heat transfer medium flows through the solar thermal module (15) through at least one inner tube (47, 48). flows through,wherein the heat transfer medium is first guided to the tip of the absorption region (30) inside the solar thermal module (15), wherein the heat transfer medium is guided from the tip of the absorption region (30) inside the solar thermal module along the remaining absorption region (30), wherein the solar thermal module (15) is adapted such that the heat transfer medium leaves through an outlet into a heat transfer medium discharge channel (6), wherein the at least one inner tube (47, 48) comprises an inner tube A (48), characterized in that a section of the inner tube A (48) is adapted to run through the heat transfer medium discharge channel (6), wherein the section of the inner tube A (48) is enclosed by an outer tube (49), wherein the outer tube (49) is adapted to form part of the wall of the heat transfer medium discharge channel (6), wherein the solar thermal module (15) has at least one spring element (51) in the force flow between the inner tube A (48) and the outer tube (49), wherein the at least one spring element (51) is adapted to compensate for a different thermal expansion of the inner tube A (48) and the outer tube (49), wherein the at least one spring element (51) has a spring force which is transmitted in the inner tube A (48) as a tensile force and in the outer tube (49) as a compressive force.

2. Solar thermal module (15) according to claim 1 with the following features, wherein the solar thermal module comprises a base plate B (33) and a guide B (36), wherein the base plate B (33) and the guide B (36) are suitable for forming lateral boundaries of the heat transfer medium discharge channel (6), wherein the guide B (36) is connected to a base plate C (37), characterized in that the solar thermal module (15) has an articulated connection on a support surface (34) between the base plate B (33) and an outer tube (49) and on a support surface (35) between the guide B (36) and the outer tube (49).

3. Solar thermal module (15) according to one of the preceding claims with the following features, wherein the solar thermal module (15) has a vertical and horizontal inner support structure on the side illuminated by the solar radiation (14), characterized in that the inner support structure consists of a base plate C (37) and a guide B (36) and a flange (40) screwed thereto, wherein the base plate C (37) is mechanically decoupled from the guide B (36) and the flange (40) by several webs (70) of the base plate C (37) distributed over the circumference being guided into indentations (71) of the guide B (36).

4. Solar thermal module (15) according to one of the preceding claims, characterized in that the connection between the heat transfer medium supply channel (5) and the inside of the tip of the absorption region (30) consists of at least two pipes (48, 47), wherein the at least two pipes are connected to one another in an articulated manner.

5. Solar thermal module (15) according to one of the preceding claims, characterized in that a base plate A (31) and an inner tube A (48), preferably all components which are adapted to conduct the heat transfer medium in the interior of the solar thermal module (15) up to the vicinity of the tip of the absorption region (30), consist of metallic materials and wherein an inner tube B (47), a cap (44) with cooling elements (45), a guide A (46), a flange (40), a base plate C (37) with cooling elements (38), a guide B (36), an outer tube (49) and a base plate B (33), preferably all components which are adapted to conduct the heat transfer medium in the interior of the solar thermal module (15) up to the tip of the absorption region (3) and away from the tip of the absorption region (30), consist of ceramic materials.

6. Solar thermal module (15) according to one of the preceding claims with the following features, wherein a plurality of cooling elements (38) are located on a base plate C (37), characterized in that the cooling elements (38) each adjoin a guide B (36) at a small distance, wherein the base plate C (37) and the guide B (36) form a flow channel for the heat transfer medium, wherein the solar thermal module (15) has a flow channel for the heat transfer medium, wherein the surfaces of the base plate C (37) and the guide B (36) are geometrically designed such that the remaining cross-sectional area of ​​the flow channel continuously decreases in the flow direction.

7. Solar thermal module (15) according to one of the preceding claims with the following features, wherein in the interior of the solar thermal module (15) there are screw connections distributed over the circumference, each comprising a screw (41) and a nut (39), characterized in that the screw has a head, wherein the head of the screw (41) is provided with at least one indentation (91), preferably with indentations (91), running all the way around in the longitudinal direction, wherein next to the head of the screw (41) there is a holding indentation (90), for example on the flange (40), and wherein the at least one indentation (91) and the holding indentation (90) are suitable for receiving a locking pin (42).

8. Solar thermal module (15) according to one of the preceding claims with the following features, characterized in that the solar thermal module (15) comprises a flange (40), an inner tube B (47), a guide A (46) and a cap (44), wherein the inner tube B (47), the guide A (46) and the cap (44) are each fastened to the flange (40) by means of bayonet locks.

9. Solar thermal receiver (4) comprising a plurality of solar thermal modules (15) according to one of claims 1 to 8, a heat transfer medium supply channel (5) and a heat transfer medium discharge channel (6), wherein the heat transfer medium supply channel (5) is connected to the plurality of solar thermal modules (15), wherein a part of the heat transfer medium discharge channel (6) is formed by an outer tube (49) of the plurality of solar thermal modules (15).

10. A method for obtaining thermal energy from solar radiation, wherein solar radiation is absorbed by means of a plurality of solar thermal modules (15) according to one of claims 1 to 8 and is converted into a heat transfer medium, wherein the heat transfer medium is guided from the plurality of solar thermal modules (15) into a heat transfer medium discharge channel (6), wherein the heat transfer medium is guided from the heat transfer medium discharge channel (6) into at least one heat consumer (8) and / or into at least one heat accumulator (7), wherein the heat transfer medium is guided from the at least one heat consumer (8) and / or the at least one heat accumulator (7) into the heat transfer medium supply channel (5), wherein the heat transfer medium is guided from the heat transfer medium supply channel (5) again into the plurality of solar thermal modules (15).

11. The method according to claim 10, wherein the heat transfer medium is passed into at least one heat consumer (8), wherein the heat consumer (8) comprises at least one heat exchanger, wherein the heat exchanger is a heat exchanger of a steam boiler and / or a preheater of a steam boiler.

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