Geothermal heat absorber and method for producing the same

Abstract

A geothermal absorber is a prefabricated module for geothermal heat absorption. The geothermal absorber of the present invention comprises a cylindrical base body containing a fluid-loaded heat exchanger (10). The end sections of the cylindrical module base body (1) are sealed in a fluid-tight manner by means of a head assembly (2) and a closure piece (3). The head assembly (2) is designed to connect the heat exchanger (10) of the geothermal absorber, located inside the cylindrical module base body (1), to a heat consumer.

Description

[0001] The present invention relates to a geothermal heat absorber with a cylindrical base body and a method for producing the same.

[0002] The state of the art includes several types of devices for extracting energy from near-surface soil. One of these devices is the geothermal energy basket, which is used vertically in the ground. The outer diameter of the geothermal energy basket is 0.5 m. The geothermal energy basket comprises a spiral-shaped PE pipe measuring 25 m x 2.5 m. The spiral has a stretched pipe length of 55 m. The coolant fluid requirement is relatively high, at approximately 35 l / kW. Extraction capacities of 500 W / basket have been measured. With the required installation grid of 4 m, this results in an area-specific extraction capacity of approximately 40 W / m² at a fluid temperature of -3°C / 0°C. Consequently, no significant market potential is expected for geothermal energy baskets.

[0003] Such devices, also known as probes, are available in lengths of 15 m or 30 m. These lengths allow the probes to be fully assembled in a vertical position only on site, where appropriate lifting equipment must be provided. Welding the components of such geothermal energy baskets can and must only be performed by trained, certified specialists.

[0004] In all state-of-the-art systems, the heat extraction capacity is relatively low, they are insufficiently economical and the energy obtained is provided at a low and therefore inefficient temperature level for a heat pump as a form of heat consumer.

[0005] The object of the present invention is to eliminate these and other disadvantages of the prior art.

[0006] This object is achieved according to the invention as defined in the characterizing part of patent claim 1.

[0007] The above object is also achieved by a method which is defined in the characterising part of claim 11.

[0008] Below, embodiments of this geothermal absorber—also referred to as "absorber" in the following description—are explained in more detail with reference to the accompanying drawings. It shows: Fig. 1 in a side view of the present geothermal heat absorber, whereby the central region of a cylindrical shell of the absorber has been omitted, Fig. 2 perspective the geothermal absorber according to Fig. 1 , Fig. 3 perspective view of the front of a connection area of ​​the absorber in Fig. 2 , Fig. 4 in a front view the connection area Fig. 3 Fig. 5 in a section AA the connection area of ​​the absorber Fig. 4 , Fig. 6 in a section BB the connection area of ​​the absorber Fig. 4 , and Fig. 7 in a perspective view the rear side of the connection area of ​​the absorber Fig. 3 .

[0009] In Fig. 1 The present geothermal absorber is shown in a side view. This absorber has a cylindrical base body and is a prefabricated module for geothermal absorption. One of the end sections of the cylindrical module base body 1 is assigned a head assembly 2, which enables connection of the geothermal absorber to surrounding devices, such as heat consumers - i.e. devices that extract heat from the geothermal absorber. The opposite end section of the module base body 1 is assigned a terminal piece 3 in the illustrated case. A central area of ​​the module base body 1 was Fig. 1 omitted so that the components of the geothermal heat absorber located inside this module base body 1 can be at least partially visible.

[0010] Fig. 2 shows the geothermal absorber in perspective Fig. 1 . The Fig. 1 and Fig. 2 The absorber shown can also be called a module for short. In principle, it is also possible to connect such modules in series, for example. This makes it possible to construct geothermal absorbers whose length is adapted to the local conditions at the site where the geothermal absorber is installed. The geothermal absorber can expediently consist of several interconnected modules, each of which has a head arrangement 2 at both ends of the module base body 1. In this way, modules or rows of modules could also be connected in parallel. The modules of the geothermal absorber are arranged or joined together horizontally – i.e. in a plane – or vertically – i.e. perpendicular to one another – or diagonally – i.e. perpendicular to one another in the ground. The second head arrangement 2 can have a different number of passages than the first head arrangement 2 of the same module, which will be described in detail later.

[0011] The cylindrical module base body 1 is made of a solid material. Advantageously, the cylindrical module base body 1 is formed from a metal tube, as metals are known to be good heat conductors. Alternatively, to reduce weight, the module base body 1 can be a hollow cylinder made of thin-walled aluminum. The module base body 1 could also be made of polyethylene (PE for short) or high-density polyethylene (HDPE for short) to simplify assembly of the geothermal heat absorber.

[0012] The head assembly 2 and the end piece 3 are either integral with the module base body 1 or are connected to this module base body 1 in a fluid-tight manner. This allows the interior of the module to be filled with a fluid. Such measures ensure a favorable transfer of heat from the soil adjacent to the module to the components of the heat absorber located inside the module.

[0013] Fig. 3 shows in perspective the head arrangement 2 of the module from Fig. 1 and Fig. 2 The head assembly 2 has an annular wall 21 in the shape of a wide ring. The thickness of this annular wall 21 is comparable to the thickness of the wall of the cylindrical module base body 1. The axis E of the annular wall 21 lies on an axis E, as shown in Fig. 1 and Fig. 4 which is common to this annular wall 21 and to the cylindrical module base body 1. One of the lateral edge sections 22 of the annular wall 21 is, in the illustrated case, firmly connected to the cylindrical module base body 1. Either the annular wall 21 is integral with the cylindrical module base body 1, or these components of the geothermal heat absorber are fluidly sealed to one another.

[0014] The remaining area of ​​the annular wall 21 protrudes from the module base body 1. The opposite, free, annular edge section 23 of the area of ​​the annular wall 21 protruding from the module base body 1 has a first indentation 24 and a second indentation 25. In the case shown, the contour of the respective first indentation 24 and the second indentation 25 has the shape of the capital letter U. In the case shown, a first leg 26 and a second leg 27 of this U-shape, which extend away from the web 28 connecting these legs 26 and 27, run parallel to one another. The first indentation 24 is located in the upper area of ​​the annular wall 21. The second indentation 25 is offset by 90 degrees in a counterclockwise direction from the first indentation 24.

[0015] The head assembly 2 further comprises a transverse wall 31 extending transversely within the annular wall 21. This transverse wall 31 is spaced apart from both the first, continuously extending edge portion 22 of the annular wall 21 and the second, annular edge portion 23 of the annular wall 21, which has the first indentation 24 and the second indentation 25. Passages for liquids are formed in this transverse wall 31. Each of these passages has an opening 32—as shown in Fig. 7 shown - in the cross wall 31. Both this cross wall 31 and the end piece 3 are designed as dished ends 6 - as shown in Fig.1 The end piece 3 comprises a curved dished bottom wall 4 and a seam 5 and is connected, glued, or welded to the module base body 1 in a fluid-tight manner. In combination with the transverse wall 31 of the head assembly 2, the absorber according to the invention forms a tank for a storage medium. Of course, the end piece 3 can also be formed integrally on the module base body 1.

[0016] The head arrangement 2 in Fig. 3 and Fig. 4 also has tubular passages 35, 36, 37 and 38. The first passage 35 is located in the middle area of ​​the transverse wall 31. The second of the passages 36 is located laterally from the first passage 35, so that these passages 35 and 36 lie in a common horizontal plane. Fig. 3 and Fig. 4 In the case shown, the second passage 36 is located to the left of the first passage 35. The third passage 37 is located above the first passage 35. And finally, the fourth passage 38 is also located above the first passage 35, but to the side of the third passage 37. The angular distance between the third passage 37 and the fourth passage 38 is expediently 45 degrees clockwise.

[0017] Fig. 5 shows a section A -A through the head assembly 2 from Fig. 4 . The Fig. 6 shows a section B - B through the head assembly 2 from Fig. 4 . The Fig. 7 shows in perspective the rear side of the head assembly 2 from Fig. 3 . The first passage 35, the second passage 36 and the fourth passage 38 have tubular nozzles 30 which - as in Fig. 5 and 6 shown - pass through the transverse wall 31 of the head assembly 2. Fig. 6 further shows that a wall section 34 of the transverse wall 31 runs between the nozzles 30. Accordingly, the nozzle 30 of the passages 35, 36, and 38 consists of a first tubular section and a second tubular section 39. The first tubular passage section is located on the outside of the transverse wall 31. The second tubular section 39 is located on the inside of the transverse wall 31. In the illustrated case, these sections 39 are integral with the transverse wall 31. The opening 32 in the transverse wall 31 is limited or defined by the clear cross-section of the tubular sections 39.

[0018] A tubular extension 40 protrudes coaxially from the inner tubular section 39. These two components of the absorber are advantageously made in one piece. The inner diameter of the extension 40 corresponds to the inner diameter of the inner tubular section 39. The outer diameter of the extension 40 is smaller than the outer diameter of the inner tubular section 39. The surface of the extension 40 is cylindrical. This allows one of the end sections of one of the tubular components of the geothermal absorber located in the module base body 1 to be plugged onto this extension 40 and firmly connected to this section 39. The diameter of the interior space in the outer tubular passage section has a diameter whose size decreases slightly from the outer opening of this passage section towards the transverse wall 31. The Fig. 3 and Fig. 7 The third passage 37 shown does not have an inner tubular section 39 located on the inside of the transverse wall 31. The third passage 37 arranged on the outside of the transverse wall 31 ends with the opening 32 in the transverse wall 31. As shown in Fig. 7 shown.

[0019] Inside the module is a fluid-loaded heat exchanger 10. This heat exchanger 10 comprises a coil that extends within the module base body 1 between the head assembly 2 and the end piece 3. A tube, expediently made of a metal, has been formed into the coil. The outer diameter of the coil turns essentially corresponds to the inner diameter of the module base body 1 of the geothermal absorber. Expediently, the outer diameter of the coil turns in their relaxed state is even slightly larger than the inner diameter of the module base body 1 of the absorber. When such a coil is then brought inside the module base body 1 of the absorber, the sections of the coil turns located on the inner wall of the module base body 1 rest on the inner wall of the housing with a prestress. This significantly improves the heat transfer from the module base body 1 to the tube wall of the coil.

[0020] The heat exchanger 10 further comprises an inlet pipe 12, as shown in Fig. 1 and Fig. 5 shown, for the introduction of an operating fluid or operating liquid into the interior of the heat exchanger 10. This operating fluid acts as a heat transfer fluid and can be a 25% ethanol-water mixture. This inlet pipe 12 is plugged or inserted at one end onto the extension 40 of the first passage 35 in the head assembly 2, see Fig. 5 , and permanently connected to one another in a fluid-tight manner. A supply line (not shown) for the operating fluid can be connected to the external nozzle 30 of the first passage 35. The other end of the inlet pipe 12 is located close to the end piece 3 of the absorber, specifically inside the absorber. The end section of the coil located in this end section of the absorber is fluidly connected to this end of the inlet pipe 12. The operating fluid can thus be guided through the first passage 35 and the inlet pipe 12 to the end of the absorber closed by the end piece 3. At this end of the inlet pipe 12, the operating fluid reaches the coil of the heat exchanger 10. After the operating fluid has flowed through the coil, it can flow out of the heat exchanger 10 at the other end of the coil through the second passage 36 in the transverse wall 31.

[0021] The heat exchanger 10 also includes a storage device. This storage device comprises a tubular lance 15 located inside the module base body 1. ( Fig. 1 ). One of the end sections of this lance 15 is directed to the extension 40 of the fourth passage 38 in the head assembly 2 - see Fig. 3 - plugged onto or inserted into it and permanently connected to one another in a fluid-tight manner. The lance 15 extends from the head assembly 2 to the vicinity of the end piece 3. The liquid storage medium is guided through this lance 15 to the vicinity of the end piece 3. This liquid can move from the end piece 3 against the head assembly 2 and thus fill the interior of an absorber housing, which is enclosed in a tank-like manner - like a reservoir - by the module base body 1, the head assembly 2 and the end piece 3. The storage medium can flow out of the absorber housing through the third passage 37 and through the opening 32 in the transverse wall 31 of the head assembly 2. The storage medium can be connected to a separate tank container by means of the third passage 37 and fourth passage 38, which is designed as an open, pressureless tank or as a closed tank with pressure equalization.

[0022] As an interactive storage medium, water can be filled with an additive that serves to lower the freezing point of water. This additive can be an antifreeze or table salt. Advantageously, the antifreeze can be biodegradable and non-polluting to groundwater and / or made from renewable raw materials, such as sugar derivatives or ethanol.

[0023] This geothermal absorber can also be designed as a prefabricated module for geothermal absorption. Such a module can have a length between 2.8 and 5.8 meters.

[0024] The intimate connection between the module base body 1 and the coil can be achieved through a suitable manufacturing process for the coil. A tube is wound onto a cylindrical template (not shown) and treated so that it permanently assumes the shape of a coil. The outer diameter of the coil thus formed approximately corresponds to the diameter of the inner surface of the module base body 1 or is slightly larger. The coil is stretched so that its outer diameter becomes smaller than the inner diameter of the module base body 1. In this stretched state, the coil is inserted into the module base body 1, after which the coil is released from the stretching force.

[0025] An alternative manufacturing process has proven particularly successful for geothermal absorber modules with a length of more than 2 m and a tube length of more than 55 m up to approximately 80 m for the coil. For this purpose, a tube is wound onto a cylindrical template and treated in such a way that the tube permanently assumes the shape of a coil. A prestress in the coil caused by the deformation of the tube is partially retained and the coil is wound with an outer diameter smaller than the inner diameter of the module base body 1. The coil is inserted into the module base body 1 in this prestressed state and then released from the prestress. The coil increases its outer diameter and rests against an inner surface of the module base body 1.

[0026] The inlet pipe 12 is finally connected to one end of the coil, and the module base body 1 is closed with the end piece 3. The other end of the inlet pipe 12 and the other end of the coil are each connected to a passage of the head assembly 2. Bezugszeichenliste

[0027] 1Module body 2Head arrangement 3End piece 4Torispherical head wall 5Seam 6Torispherical head 10Heat exchanger 12Inlet pipe 15Lance 21Annular wall 22Edge section 23Annular edge section 24First indentation 25Second indentation 26First leg 27Second leg 28Web 30Pipe 31Cross wall 32Opening 34Wall section 35First passage 36Second passage 37Third passage 38Fourth passage 39Tubular section 40Extension EAxis

Claims

1. Geothermal absorber with a cylindrical base body, characterized in that the geothermal heat absorber is a prefabricated module for geothermal heat absorption, that a fluid-loaded heat exchanger (10) is accommodated within the module base body (1), and that the module has a head arrangement (2) with the aid of which the heat exchanger (10) of the module can be connected to a heat consumer.

2. Geothermal absorber according to claim 1, characterized in that the head arrangement (2) is located in the region of at least one end part of the module base body (1), that this head arrangement (2) has a transverse wall (31), and that this transverse wall (31) carries at least one tubular passage (35, 36, 37, 38) which allows the passage of a liquid through the transverse wall (31).

3. Geothermal absorber according to claim 1 or 2, characterized in thatthe head arrangement (2) comprises at least one annular wall (21) which has the shape of a wide ring, that this ring lies on an axis (E) common to the cylindrical module base body (1) and that this wide ring protrudes from the module base body (1).

4. Geothermal absorber according to claim 3, characterized in that an edge portion (22) of the annular ring wall (21) is firmly connected to the cylindrical module base body (1), and that an annular edge portion (23) of the ring wall (21) facing away from the module base body (1) is provided with an indentation (24, 25).

5. Geothermal absorber according to claim 1, characterized in thatthe heat exchanger (10) comprises a coil which is located inside the module base body (1), that an outwardly facing part of the coil of the heat exchanger (10) rests with prestress on an inner surface of the cylindrical module base body (1), and that one end of the heat exchanger (10) is fluidically connected to an inner tubular section (39) of one of the passages (35, 36).

6. Geothermal absorber according to claim 1 or 5, characterized in that the heat exchanger (10) is filled with an operating fluid.

7. Geothermal absorber according to one of claims 1 to 5, characterized in thata storage device is arranged inside the fluid-tight module base body (1), that this storage device comprises a tubular lance (15), that an end piece of the lance (15) is fluidically connected to the inner tubular section (39) of another of the tubular passages (35, 36, 37, 38) in the head arrangement (2), that the lance (15) extends into the region of the opposite end part of the cylindrical module base body (1), that the storage device comprises an opening (32) in the transverse wall (31) through which a storage medium that contacts the majority of the heat exchanger (10) can leave an interior space enclosed by the cylindrical module base body (1), and that the storage device also comprises an interactive storage medium in some cases.

8. Geothermal absorber according to claim 7, characterized in thatthe interactive storage medium contains water and the water comprises an additive which serves to lower the freezing point of water, whereby this additive can be an antifreeze or table salt.

9. Geothermal absorber according to claim 2, characterized in that both the end piece (3) and the transverse wall (31) are designed as a dished end (6).

10. Geothermal absorber according to one of the preceding claims, characterized in that several of the modules are connected together, that the modules are connected in parallel and / or in series, and that arrangements consisting of such modules can be arranged horizontally or vertically or obliquely.

11. A method for producing the geothermal absorber according to any one of claims 1 to 10, characterized in thata tube is wound onto a cylindrical jig and treated in such a way that the tube permanently assumes the shape of a helix, wherein a prestress occurring in the helix due to the deformation of the tube is maintained and the helix is ​​wound with an outer diameter smaller than the inner diameter of the module base body (1), that the helix is ​​introduced into the module base body (1) in this prestressed state and that the helix is ​​then released from the prestress and the helix rests against an inner surface of the module base body (1).

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