DE20101139U1 - Collector module - Google Patents

Description

SRU-G

19 January 2001

me/aew/af/fri/hue

G:\IJBFUL\SGWWPT\ALL0843

Schott tubular glass

Erich-Schott-Strasse 95666 Mitterteich

Collector module

Collector module

Description

The invention relates to a collector module with a collecting pipe which has at least one inlet and one outlet for a heat transfer medium, and with at least one coaxially flowing collector pipe which has a cladding pipe, an absorber pipe and a coaxial pipe.

The coaxially flowing collector pipes are collector pipes with a direct flow through absorber. These collector pipes have a cladding pipe, an absorber pipe and a coaxial pipe. These three pipes are arranged inside each other, with the cladding pipe on the outside, the absorber pipe eccentrically or coaxially to the cladding pipe and the coaxial pipe coaxially to the absorber pipe. The cladding pipe and the absorber pipe are sealed against each other. In the space between the cladding pipe and the absorber pipe there is either a vacuum or an inert gas. This is primarily used to insulate the absorber pipe from the environment. The absorber pipe is coated with an absorber to absorb the sun's heat. In order to transport this heat further, a heat transfer medium flows through the absorber. In the case of coaxially flowing collector pipes, the heat transfer medium is introduced through a coaxial pipe. This is a pipe that is open on both sides and enters the absorber pipe through one of the two pipe ends. The other end of the absorber pipe is closed. The end of the coaxial pipe that does not extend into the absorber pipe is connected to the inlet of the collector pipe. The heat transfer medium flows through the inlet into the coaxial pipe and from there

through the absorber pipe back to the outlet. From the outlet of the collecting pipe, the heat transfer medium is led to a heat exchanger, where it transfers the heat to the storage tank.

Various coaxially flowing tube collectors are available on the market. A widely used tube collector has separate lines for the inlet and outlet of the collecting pipe. Flexible corrugated pipes are used as the inlet and outlet. The absorber pipe and the coaxial pipe are connected to the inlets and outlets using compression fittings. This type of assembly is very complex and relatively expensive. The use of separate lines for the inlet and outlet also requires more space. When using flexible corrugated pipes, a housing for the collecting system must also be provided.

The tube collectors described above are usually built as modules made up of several collector tubes that are connected to a common inlet or outlet. The individual collector modules can be combined with one another using double O-ring plug connections.

Another commercially available coaxial flow tube collector also has a coaxial flow through the collecting pipe. Both the absorber and coaxial pipes as well as the outer coaxial pipe of the collecting pipe are made as a single piece. This has the advantage that only the cladding pipe has to be sealed against the absorber pipe. However, the manufacture of these tube collectors is very complex.

Another coaxially flowing tube collector is described in DE 298 08 532 Ul. There, the collecting pipe is designed as a collecting box arrangement. The inlet and the outlet are designed as two parallel, one-piece channels that are only separated by a wall, the

has respective openings for the individual coaxial pipes. The coaxial pipe is inserted into the openings in the partition wall, the absorber pipe is received in an opening in the side wall of the collecting box, which is connected to the outlet channel, and the cladding pipe is received in an extension of the housing. All three pipes are connected to the housing parts or collecting box parts using adhesive. This does indeed achieve a more compact design. However, the seal that can be achieved using the adhesive has proven to be inadequate under high heat loads.

Against this background, it is the object of the present invention to provide a collector module which combines the advantages of both mounting and good sealing and which should also ensure a long service life.

This object is achieved by a collector module according to claim 1.

The collector module according to the invention is very easy to install. In the event that the coaxial pipe is not firmly connected to the absorber pipe and the cladding pipe, the coaxial pipe is first inserted through the nipple into the receiving element of the inlet. An elastic element is then inserted into the absorber pipe at the end facing away from the collector system. The absorber pipe is then placed over the coaxial pipe and over the nipple of the collector system.

Thanks to the sealing element between the nipple and the absorber pipe, no heat transfer medium can escape between the nipple and the absorber pipe. The elastic element, which is arranged in the absorber pipe, in turn presses the coaxial pipe into the receiving element of the inlet. The heat transfer medium can now flow from the inlet into the coaxial pipe, flow into the absorber pipe at the opposite end of the coaxial pipe and

back between the nipple and the coaxial pipe into the outlet.

If the collector pipe is not connected to the absorber pipe, it is subsequently pulled over the absorber pipe. If the absorber pipe and the collector pipe are firmly connected to each other, the absorber and collector pipe are pulled over the coaxial pipe and the nipple at the same time.

In order to ensure an uninterrupted flow of the heat transfer medium even with a high sealing performance of the elastic element, the elastic element is advantageously designed as a spiral spring.

The sealing element between the nipple and the absorber pipe is advantageously designed as at least one O-ring. This not only provides the best sealing performance, but O-rings are also inexpensive and easy to install. By choosing a suitable plastic, it is also possible to optimize the service life despite the heat load during continuous operation.

Advantageously, the at least one absorber tube and the at least one cladding tube are formed as one piece. This has the advantage that the vacuum or the inert gas atmosphere that exists between the absorber tube and the cladding tube in order to ensure that the solar collector functions properly is not subsequently impaired by, for example, leaks at the connection between the absorber tube and the cladding tube.

The collector tube is the sheathing tube that allows sunlight to pass through. It is made of a transparent material. Although it is generally a material with low thermal conductivity, this property is not crucial, as the tube is not designed to heat up very much. The sheathing tube is preferably made of glass. A low-iron glass is preferred.

(sodium-lime glass or borosilicate glass) with high solar transmission and low production costs, such as is used as primary packaging for pharmaceutical products. The cladding tube can also be made of a transparent plastic, such as polymethylmethacrylate (PMMA). Compared to plastic, glass has the advantages of higher diffusion resistance and higher UV stability, while plastic is more shatter-proof and easier to handle than glass. The cladding tube is provided with a reflector in most designs.

The absorber tube is made of a material with high temperature resistance (up to at least 250° C) and low thermal conductivity. Materials with low thermal conductivity are understood to be materials that have a specific thermal conductivity λ of < 2 J/msK. The inner tube is preferably made of glass, preferably borosilicate glass. It can also be made of a temperature-stable plastic. It is provided with an absorber.

Preferably, both the at least one absorber tube and the at least one cladding tube are made of glass. The absorber tube and the cladding tube are advantageously fused together eccentrically. Large radii are formed at the fusion point to reduce stress in the glass.

In a preferred embodiment, the collecting system is designed as a collecting pipe, which has at least one distributor plate, which is arranged in the longitudinal direction in the collecting pipe, so that the collecting pipe is divided into at least one inlet chamber and at least one outlet chamber. The receiving element for the coaxial pipe of the inlet chamber is arranged in the distributor plate. By designing the collecting system as a single-pipe system, only one

connection point is required. In addition, a single manifold requires less space and installation is less complex.

The distributor plate is preferably made of metal. The spring force of the elastic element also presses the metal distributor plate against the coaxial pipe. If the pressure increases suddenly (e.g. due to steam hammer), the distributor plate is deflected by the counterforce of the compression spring. This creates a gap between the distributor plate and the collector pipe along the pipe axis, which enables pressure equalization between the inlet and outlet chambers.

The effect just described is advantageously enhanced by a suitable fastening of the distributor plate in the collecting pipe, for example by connecting the distributor plate to the collecting pipe only via two opposite edges, preferably the opposite edges of the distributor plate in the axial direction of the collecting pipe.

The distributor plate advantageously has at least one flap which, when open, connects the at least one inlet and the at least one outlet chamber and, when closed, separates the at least one inlet and the at least one outlet chamber. Such a flap on the distributor plate, which is only pressed against the collecting pipe by the flow of the heat transfer medium, enables rapid venting of the entire system. Before the collector starts, the flap on the distributor plate enables convection between the coaxial pipe and the absorber pipe. This improves heat transport in the collector collecting pipe.

In a further preferred embodiment, the distributor plate is replaced by an inner tube arranged in the collecting tube. The inner tube forms

the inlet chamber and the volume between the inner pipe and the collecting pipe forms the outlet chamber.

On the one hand, the inner tube can be cylindrical, with its rear end in the direction of inlet flow being closed. This closure can be a disc or cap attached by soldering or another type of fastening, for example. At its open end, however, the inner tube is sealed against the collecting tube by means of a sealing ring. For better stabilization, the inner tube can also be centered at its closed end relative to the collecting tube by means of a perforated ring. The perforations in the centering ring serve to allow the heat transfer medium to flow away.

On the other hand, the inner tube can be essentially cylindrical, with its rear end in the inlet flow direction slowly converging so that this end is closed. This can be achieved, for example, by squeezing the inner tube. At its open end, such an inner tube would be sealed against the collecting tube by means of a conical fit.

It has proven particularly advantageous to design the at least one element for receiving the coaxial pipe either as a bore with a curved countersink or as an open bowl. Receiving elements designed in this way serve both to guide the coaxial pipe and to seal it.

In order to be able to vent the collector module more quickly when it is put into operation, the inner tube advantageously has a small opening at its closed end.

The collector module advantageously has a housing in which both the collecting system and at least one collector pipe are housed. The housing serves to mechanically stabilize the collector module as a whole. It is advantageous if the cladding pipe is connected to the housing. The connection can be designed to be positively locked by having a bead in the cladding pipe in the housing and either a bead in the housing or an O-ring groove with O-rings. Force-locking connections are also possible, which can be designed, for example, as an O-ring on the cladding pipe and an O-ring groove in the wall of the housing.

Another way of connecting the cladding tube to the housing is to attach clips, locking rings and/or safety bars around the cladding tube, which are also embedded in the housing. For additional safety, a bracket can also be placed around the collecting system, particularly in its design as a collecting tube, and this bracket can be attached to the safety bar. These safety elements absorb the forces that can occur, for example, due to the excess pressure in the system or the thermal changes in length of the individual components.

In the case of collector modules with more than one collector pipe, the individual collector pipes are preferably connected in parallel, with all collector pipes being fed with heat transfer medium from the same inlet and the heat transfer medium flowing from all collector pipes into the same outlet. Individual collector modules can be connected in series.

The collector modules can be connected to each other via a plug-in system attached directly to the collector system. Particularly preferred

Double O-ring systems are used. It can also be advantageous to place an additional clamp around the connection.

The subject matter of the invention will now be explained by way of example with reference to the following drawings, in which:

Figure 1 shows a section in the flow plane through a collector module;

Figure 2a-2g sections perpendicular to the flow plane through different embodiments of a collector module;

Figure 3 shows a possible connection of the cladding tube with the housing;

Fig. 4a, 4b the fluidic connection of collector tubes in a collector module with the help of distributor plates;

Fig. 5a,b the connection of several collector modules.

Figure 1 shows a collector module 1 with collector tubes 3. The heat transfer medium flows through the inlet chamber 9 into the coaxial tubes 6 of the individual collector tubes 3, flows through each coaxial tube 6 to its end opposite the inlet chamber 9, where it exits the coaxial tube 6 and flows back through the absorber tube 5 of each collector tube 3 into the outlet chamber 10, which is arranged parallel to the inlet chamber 9. From there, the heat transfer medium is fed to a device for converting the heat into energy or into a heat storage device.

The inlet chamber 9 and the outlet chamber 10 are formed by a collecting pipe 2, which is divided by a distributor plate 7 into two halves, namely the inlet chamber 9 and the outlet chamber 10. The distributor plate 7 has openings with rivets 13 for receiving the

Coaxial tubes 6. The coaxial tubes 6 are inserted into the rivets 13 and pressed against the rivets 13 and the distributor plate 7 by springs 11 which are arranged in the absorber tubes 5 at the end opposite the collecting tube, so that a sealing function is achieved.

The absorber tube 5 is made of glass in one piece with the cladding tube 4. The unit consisting of absorber tube 5 and cladding tube 4 is connected in a sealing manner via nipples 12, which are provided in the collecting tube 2 and each have two O-rings 15. The heat transfer medium can flow through the space between the inner wall of the nipple 12 and the outer wall of the coaxial tube into the outlet chamber 10.

Figures 2a to g show sections perpendicular to the flow plane of the heat transfer medium through various embodiments of the collector module at the location of a collector pipe. In all seven embodiments, the inlet and outlet chambers are formed by a collector pipe 2, which is divided into two chambers in the longitudinal direction by means of a distributor plate 7 or an inner pipe 21. A two-part housing 17 is arranged around the collector pipe 2. The housing also encompasses the end of the cladding pipe 4 facing the collector pipe.

In Figures 2a and 2d, the cladding tube 4 is positively connected to the housing 17 in that the cladding tube has a bead and the housing 17 has an O-ring groove. A sealing O-ring 15 is arranged between the bead 14 and the O-ring groove. In Figure 2c, the cladding tube 4 is also positively connected to the housing 17. The cladding tube 4 has a bead 14 and the housing 17 has a corresponding bead 18. The connection between the cladding tube 4 and the housing 17 can also be designed to be non-positive, as shown in Figure 2b. For this purpose, a sealing O-ring 15 is arranged in an O-ring groove in the

An O-ring 15 is arranged in the housing 17 without a bead being provided in the cladding tube 4.

In the embodiments shown in Fig. 2e to g, a different type of fastening of the cladding tube 4 to the housing 17 or the collecting tube 2 was chosen. A clip 25 is inserted into the bead 14 of the cladding tube 4. The clip 25 is prevented from opening by the locking ring 24. On the side facing away from the collecting tube 2, the clip 25 is provided with a shoulder 26. The cladding tube 4 is pushed into the beam 27 with the clip 25 and the locking ring 24. The entire system is supported on the beam 27 with the shoulder 26. The holes in the beam 27 are dimensioned such that the cladding tube 4 has sufficient freedom of movement when the collecting tube 2 expands thermally. This compensates for the changes in position that can occur due to the change in length of the collecting tube 2 in particular.

The excess pressure also prevailing in the system causes pull-out forces between the manifold 2 and the collector pipe from the cladding pipe 4, the absorber pipe 5 and the coaxial pipe 6. In order to absorb these pull-out forces, the beam 27 is fixed to the manifold 2 using the bracket 28 (see Fig. 2g). To do this, the bracket 28 is attached to the beam 27 using nuts 30. The collector module assembled in this way can then be placed in the insulating shells 22, which together with the outer housing wall 23 form the housing 17.

A particular advantage of this method of fastening is that the individual components have freedom of movement in all directions, which enables the collector modules to be installed on a roof without stress. All embodiments 2a to g have the advantage that individual collector pipes can be easily replaced in systems that have already been installed.

I Ir

In all seven embodiments, the absorber tube is sealed by a nipple 12 soldered to the collecting tube 2 with two O-rings 15 over which the absorber tube is slipped. In the embodiments shown in Fig. 2a-d, the coaxial tube 6 arranged in the absorber tube 5 is held either by rivets 13 arranged in the distributor plate 7 or by holding elements 20 which are produced by deep-drawing the distributor plate 7 if the latter is made of metal. To seal and fix the coaxial tube in the distributor plate 7 or the holding element 20 or the rivet 13, the coaxial tube 6 is pressed against the holding element 20 or the rivet 13 by a spring arranged in the absorber tube 5 at the end opposite the collecting tube 2. Even in the case of the distributor plate being made of plastic, as shown in Figure 2d, the coaxial tube 6 is pressed against the receiving element formed in the distributor plate via the spring 11.

In the variants with inner tube 21 shown in Figs. 2e to g, the element 20 for receiving the coaxial tube 6 is designed either as a cup with a perforated bottom as in Fig. 2e or simply as a bore with a curved or oblique countersink as in Fig. 2f,g. This guides the coaxial tube 6 on the one hand and seals it on the other.

In all seven embodiments shown in Figures 2a to 2g, the main focus is on the fact that the individual components of the collector module can be tightly connected to one another by simply plugging them together.

Figure 3 illustrates again how the connection between the cladding tube 4 and the housing 17 can be designed in a form-fitting manner. The form-fitting connection is achieved by the bead 18, which engages in the bead 14 in the cladding tube 4. For the external seal, however, grooves 16 are provided in the housing 17 for receiving O-rings 15. These O-rings 15 press against

It »«I *<<

the outer wall of the cladding tube 4 and thereby lead to a seal between the housing 17 and the cladding tube 4.

Figure 4a shows a collector module 1 which has fourteen collector tubes 3a, b. The inlet chambers 9a, b and outlet chambers 10a, b are formed by a collecting tube 2 which is divided into the various chambers by two distributor plates 7a and 7b. The first seven collector tubes 3a are fed with heat transfer medium through the inlet chamber 9a, which is the first in the flow direction of the heat transfer medium. The heat transfer medium flows out of all seven collector tubes 3a via the outlet chamber 10a. The first seven collector tubes 3a are therefore connected in parallel.

The outlet chamber 10a opens into the second inlet chamber 9b. The remaining seven collector tubes 3b are fed with heat transfer medium via the inlet chamber 9b. The heat transfer medium flows out of all of these seven collector tubes 3b through the outlet chamber 10b. The heat transfer medium is discharged via the connector 19 for further use of the heat.

In the collector module 1 shown in Figure 4a, seven collector tubes are connected in parallel to units 7a and 7b, and these units are in turn connected in series with each other. This allows for more efficient use of the heat, since the heat transfer medium that flows into the second unit 7b from the collector tubes 3b has already been preheated by passing through the first unit 7a of seven collector tubes 3a.

The inlet chamber 9a is separated from the inlet chamber 9b by a flap 8. This is shown enlarged in Figure 4b. The flap 8 is arranged in the collecting pipe 2 in such a way that it is separated from the flowing

Heat transfer medium is pressed against the collecting pipe 2 and thus tightly separates the inlet chamber 9a from the inlet chamber 9b. When the collector module 1 is filled, the flap 8 opens so that the entire collector module 1 can be vented more quickly.

Fig. 5a shows collector modules 1 in which the collecting system is designed as a collecting pipe 2 and an inner pipe 21. The interior of the inner pipe 21 forms the inlet chamber 9, and the space between the inner pipe 21 and the collecting pipe 2 forms the outlet chamber 10. The inlet chamber 9 is sealed off from the outlet chamber 10 by the sealing ring 31 and the soldering cap 32. To mechanically stabilize the inner pipe 21, a centering ring 29 is also provided at the end of the inner pipe 21 covered by the soldering cap 32. The centering ring 29 has openings so that the heat transfer medium can flow undisturbed in the outlet chamber 10. Collector modules 1 can be connected to one another using the connecting elements 35. The connecting element 35 shown in Fig. 5a is firmly connected to the collecting pipe 2 of one collector module 1. Each connecting element 35 has three grooves 16, two of which each accommodate an O-ring 15. The third groove 16 is intended for the clamp 30. While the O-rings 15 primarily have a sealing function, the clamp 30, which is also enlarged in the lower part of the image and shown from the side, is used to actually attach one collector module 1 to the other collector module 1. With the help of the clamp 30, the collector modules 1 are secured against accidental pulling apart.

Fig. 5b also shows two collector modules 1 that are connected to one another. These are collector modules in which the collecting pipe 2 and the inner pipe 21 were produced by internal high-pressure forming. The inner pipe 21 is sealed against the collecting pipe 2 on the one hand by a conical fit 33 and on the other hand by

a squeeze at the opposite end 34 of the inner tube. The inner tube 21 thus forms the inlet chamber 9. The space between the inner tube 21 and the collecting tube 2 forms the outlet chamber 10. Here too, the connecting element 35 between the two collector modules 1 is a double O-ring plug connection. The end of the collecting tube 2, on which the conical fit 33 of the inner tube 21 is located, has internal grooves 16 for receiving O-rings. This end, together with the O-rings 15, is pushed onto a collecting tube end that has not been further processed on the closed inner tube side of another collector module 1.

The inner tube 21 can, regardless of its specific design, have a small opening at the rear end in the flow direction, which allows faster venting of the collector module 1 when the collector is put into operation.

Claims (20)

1. Collector module with a collecting system ( 2 ) which has an inlet ( 9 ) and an outlet ( 10 ) for the heat transfer medium, and with at least one coaxially flowing collector tube ( 3 ) which has a jacket tube ( 4 ), an absorber tube ( 5 ) and a coaxial tube ( 6 ), characterized in that - that the outlet ( 10 ) has at least one hollow nipple ( 12 ) extending in the radial direction of the collecting system ( 2 ), onto which the at least one absorber pipe ( 5 ) is coaxially fitted, wherein at least one sealing element ( 15 ) is arranged between the nipple ( 12 ) and the absorber pipe ( 5 ), - that the inlet ( 9 ) has at least one element ( 13 , 20 ) for receiving the coaxial tube ( 6 ), and - that the at least one coaxial tube ( 6 ) is arranged coaxially within the nipple ( 12 ) and is pressed against the receiving element ( 13 , 20 ) by an elastic element ( 11 ) at the end of the absorber tube ( 5 ) facing away from the collecting system ( 2 ). 2. Collector module according to claim 1, characterized in that the elastic element is designed as a spring ( 11 ). 3. Collector module according to one of claims 1 or 2, characterized in that the at least one sealing element is designed as at least one O-ring ( 15 ). 4. Collector module according to one of claims 1 to 3, characterized in that the at least one absorber tube ( 5 ) and the at least one cladding tube ( 4 ) are formed in one piece. 5. Collector module according to one of claims 1 to 4, characterized in that the at least one absorber tube ( 5 ) and the at least one cladding tube ( 4 ) are made of glass. 6. Collector module according to one of claims 1 to 5, characterized in that the collecting system is designed as a collecting pipe ( 2 ) which has at least one distributor plate ( 7 ) which is arranged in the longitudinal direction in the collecting pipe ( 2 ) so that the collecting pipe ( 2 ) is divided into at least one inlet chamber ( 9 ) and at least one outlet chamber ( 10 ), the distributor plate ( 7 ) having at least one element for receiving the coaxial pipe ( 6 ). 7. Collector module according to claim 6, characterized in that the distributor plate ( 7 ) is made of metal. 8. Collector module according to one of claims 6 or 7, characterized in that the distributor plate ( 7 ) is fastened in the collecting pipe ( 2 ) in such a way that it yields when pressure is applied to the distributor plate surface. 9. Collector module according to one of claims 6 to 8, characterized in that the at least one distributor plate ( 7 ) has a flap ( 8 ) which, when open, connects the inlet ( 9 ) and the outlet ( 10 ) and, when closed, separates the inlet ( 9 ) and the outlet ( 10 ). 10. Collector module according to one of claims 1 to 5, characterized in that the collecting system is designed as a collecting pipe ( 2 ) which has a coaxially arranged inner pipe ( 21 ), so that the collecting pipe ( 2 ) is divided into at least one inlet chamber ( 9 ) and one outlet chamber ( 10 ), wherein the inner pipe ( 21 ) has at least one element ( 13 , 20 ) for receiving the coaxial pipe ( 6 ). 11. Collector module according to claim 10, characterized in that the inner tube ( 21 ) is cylindrical and its rear end in the inlet flow direction is closed. 12. Collector module according to claim 10 or 11, characterized in that the inner tube ( 21 ) is sealed at its open end against the collecting tube ( 2 ) by means of a sealing ring ( 31 ). 13. Collector module according to one of claims 10 to 12, characterized in that the inner tube ( 21 ) is centered at its closed end relative to the collecting tube ( 2 ) by means of a perforated ring ( 29 ). 14. Collector module according to claim 10, characterized in that the inner tube ( 21 ) is substantially cylindrical and its rear end in the inlet flow direction converges so that this end is closed. 15. Collector module according to claim 10 or 14, characterized in that the inner tube ( 21 ) is sealed at its open end against the collecting tube ( 2 ) by means of a conical fit ( 33 ). 16. Collector module according to one of claims 10 to 15, characterized in that the at least one receiving element ( 13 , 20 ) is designed as a bore with a curved countersink. 17. Collector module according to one of claims 10 to 15, characterized in that the at least one receiving element ( 13 , 20 ) is designed as an open cup. 18. Collector module according to one of claims 10 to 17, characterized in that the inner tube ( 21 ) has a small opening at its closed end. 19. Collector module according to one of claims 1 to 18, characterized in that it has a housing ( 17 ) in which both the collecting system ( 2 ) and partly the at least one collector pipe ( 3 ) are accommodated. 20. Collector module according to claim 19, characterized in that the cladding tube ( 4 ) is connected to the housing ( 17 ).