WO2013091853A1

WO2013091853A1 - Geothermal probe assembly

Info

Publication number: WO2013091853A1
Application number: PCT/EP2012/005270
Authority: WO
Inventors: Jörg STOSCHUS
Original assignee: Rehau Ag + Co
Priority date: 2011-12-21
Filing date: 2012-12-19
Publication date: 2013-06-27
Also published as: DE202011052396U1

Abstract

The invention relates to a geothermal probe assembly (1) to be introduced into a cavity (5) in the ground (8), in which two pipes (2, 2') are provided, one of which is provided as a flow and the other as a return for a fluid flowing therethrough. The geothermal probe is characterized in that at least one element (4) is arranged on at least one pipe (2, 2'), which element spaces the pipe (2, 2') introduced into the cavity (5) in the ground (8) apart from the wall (6) of the cavity (5).

Description

Geothermal probe arrangement

The invention relates to a geothermal probe assembly and means for exchanging heat energy with the ground.

The use of renewable energy sources is currently the focus of many activities to ensure energy supply. Of great importance here is the use of the soil as a heat source and heat storage.

With the aid of geothermal probe arrangements, it is possible to remove thermal energy from the ground, for example for heating purposes, but also to supply heat energy to the earth in order to cool buildings, for example, and then remove the thermal energy temporarily stored in the ground for heating purposes.

For this purpose, a variety of geothermal probe arrangements is known from the prior art, which are introduced into corresponding cavities in the ground and there accomplish the heat energy exchange with the ground.

In particular, for certain geothermal probes a cavity in the ground is created by a drilling process, in which quite wells of 300 m and more can be achieved to incorporate these probes therein.

Here, aquifers (aquifers) are also drilled in the soil.

After the introduction of the probe into the cavity of the remaining space between geothermal probe and borehole wall is suitable to fill. It is important to ensure that the aquifers are safely separated from each other, so that no mixing of the different groundwater takes place. Furthermore, it is very important for the effectiveness of a geothermal probe assembly that the thermal connection to the soil is well executed.

Voids in the backfill material, which can not escape when filling, particularly hinder the thermal connection to the ground and reduce the effectiveness of the geothermal probe assembly.

This problem has been solved inadequately, because the geothermal probe could not be ideally placed in the wellbore, but because it can occur due to twists and by the inherent stresses during winding in the pipe that the pipe rests against the borehole wall.

Furthermore, for example, also stones from the wall of the borehole, whereby a filling to a necessary extent and the escape of air bubbles is difficult.

This is where the invention, which has set itself the task, a

Specify geothermal probe assembly that overcomes the disadvantages of the prior art and in particular allows to simplify the filling of the existing space between geothermal probe and borehole wall and make safe.

Another object of the invention is to provide a device for exchanging thermal energy with the ground.

The task of specifying a geothermal probe assembly is achieved with a

Geothermal probe arrangement according to claim 1.

In the context of the present invention it has been recognized that a

Geothermal probe assembly for introduction into a cavity in the ground, in which two tubes, one of which is provided as a flow and the other as return for a fluid flowing through, then in the context of the invention is advantageous if at least one tube at least one element is arranged which spaces the tube inserted into the cavity in the ground from the wall of the cavity.

In the context of the invention, the geothermal probe arrangement is understood to mean the following: A borehole heat exchanger is in this case installed in a ground hole borehole or free space, which is generally introduced vertically into the ground, from pipes, in particular plastic pipes. This may be a probe having two pipes for the supply and return of the fluid, wherein the two pipes for supply and return of the fluid at their ends by a connector, a so-called. Probe foot, are connected.

In another embodiment, a so-called. Coaxial probe can be used, in which an inner tube is arranged in the lumen of an outer tube, wherein the outer tube depending on the configuration forms the flow or the return and the inner tube then corresponding to the return or the flow ,

The outer tube is closed at its lower end in a suitable manner, for example by a blind plug. These geothermal probes are suitable to extract heat from the ground and to provide, for example, for heating purposes of a building.

On the other hand, the geothermal probes are also designed to deliver heat energy extracted from the building to the earth, for example for cooling purposes of the building.

This heat energy extracted from the building and supplied to the ground can be particularly advantageously temporarily stored in the ground and then available, for example, in the winter season for heating purposes in which the geothermal probe can then extract heat energy for heating purposes from the heated soil.

That this a piping of the geothermal probe with the components of a Heizbzw. Cooling device of a building are necessary, as well as pumps to transport the fluid through the geothermal probe and possibly also heat pumps to bring the energy gained from the soil to a higher, in particular usable temperature level is assumed to be known from the prior art , According to the present invention, it is provided that a underground geothermal probe is used.

Such a U geothermal probe consists of at least two tubes, which are provided for the flow and return of the heat transfer fluid.

Also so-called. "Double-U probes" are known in these four pipes are provided, two forward and two returns.

Such underground geothermal probes are associated with the disadvantage that they can suffer a "thermal short circuit" when installed in the cavity in the ground by a certain length of the two tubes, one of which the flow and the other of the return for the conductive Form heat transfer fluid, abut each other.

A "thermal short circuit" is undesirable, since thereby the performance of the geothermal probe assembly is reduced by the soil extracted heat can not be fully utilized by these proportions, for example, from the return proportionally immediately on the supply passes or by heat to be stored in the ground from the flow In both cases, the efficiency of the probe is minimized.

A thermal short can no longer be repaired on a probe installed in the ground. This thermal short circuit is caused by the inventive

Geothermal probe assembly minimized or avoided.

In this way, a thermal short circuit over the length or over most of the length of the two approximately parallel tubes can be minimized or avoided.

In the context of the present invention, it has been found advantageous that the tubes of the geothermal probe assembly are to be spaced from the wall of the introduced into the ground cavity so that a secure backfilling of this space between geothermal probe and wall of the cavity can be done. A secure backfilling of the free space can take place when at least one element is arranged on at least one tube, which space the tube introduced into the cavity in the ground from the wall of the cavity. It has proved to be particularly favorable in the context of the present invention, when the element with which the spacing of the tube is formed by the wall of the cavity in the ground, is formed integrally with the tube.

The integrally formed with the tube element may in this case contain a polymer material or consist of polymer material, wherein the polymer material is preferably selected from a polyolefin, particularly preferably from a polyethylene or a polypropylene or a crosslinked polyethylene.

In this context, it is particularly advantageous if the tube and the element consist of the same polymer material, so that they can be produced in any length of time in a continuous shaping process, for example an extrusion process.

A polyolefin is easy to process, excellently recyclable and cost effective.

Polyethylene is a particularly preferred material for this purpose, which has a high toughness and is inert to most substances that occur in the ground and are included in the course of the geothermal probe assembly flowing through fluid.

Also, polypropylene is, with certain limitations, a polymer material suitable for this purpose. A cross-linked polyethylene is particularly preferred for the production of a geothermal probe assembly of the present invention, since this material is particularly tough, the possible damage particularly well with the introduction into the cavity in the ground, durable and above all is extremely inert against the most diverse substances. The element, which in the context of the present invention causes the spacing of the tube to the wall of the cavity in the ground, has a longitudinal extent and is thus arranged along at least part of the length of the tube. Preferably, the element may be formed as a web which is arranged in the axial direction on the outer surface of the tube and comprises a part of the length of the tube or the entire length of the tube.

It has proved to be particularly favorable if a plurality of elements are arranged on the pipe in such a way that they are approximately equally spaced along the circumference of the pipe.

As a result, a plurality of elements along the circumference of the tube can be arranged such that they approximately equally spaced the distance of the tube to the wall of the borehole in the ground in all directions in a plane perpendicular to the tube axis cutting plane and thus approximately center the tube in the borehole.

It has proved to be preferred in the context of the present invention, when the element is formed as a web, in T-shape, in H-shape, in O-shape, in V-shape or in a mixed form of the aforementioned forms.

Particularly preferred is a T-shape for the element, wherein the "foot" of the T-shape is connected to the pipe, while the wide "projecting" on both sides "head portion" of the T-shape against the wall of the borehole in the soil and thereby the pipe is supported and centered largely in the borehole.

In this way, it is possible in a simple way to modify the element such that it causes a safe spacing of the tube from the wall of the cavity in the ground. The geothermal probe arrangement according to the invention has further advantages:

In addition to the safe spacing of the tube from the wall of the cavity in the ground, the tube, in particular with the element or elements on an enlarged exchange surface and is thus able to exchange more heat energy with the ground.

As a result, the effectiveness of this geothermal probe arrangement can be increased. Another advantage is that it may be provided in a coaxial probe to provide the inner tube with the elements and thus to achieve a spacing of the inner tube from the inner wall of the outer tube. As a result, a thermal short circuit can be minimized or avoided. This increases the effectiveness of such a coaxial probe.

Advantageously, it can also be provided that, in the case of a helix probe which comprises a tube which extends approximately straight, around which the second tube is wound in a helical turn, the two tubes being connected to one another, the elements for spacing from the wall of the bore hole to provide in the ground.

In particular, a helical depth probe, in which a helix probe is inserted into great depths in the ground, such as 150 m and more, can advantageously be operated by providing these elements for spacing from the wall of the borehole in the ground.

When filling the geothermal probe assembly according to the present invention, the backfill material is introduced from above / from the earth's surface into the cavity in the ground.

For this purpose, the filling material is chosen so that it is as low-viscosity as possible and has a high thermal conductivity.

An advantage of this geothermal probe assembly according to the invention that the backfill material along the pipe circumference about equally spaced elements and consequent spacing of the tubes to the wall of the well in the ground, the tubes are approximately centered in the borehole, in a simple manner can be introduced. The filling material can follow the path given by the elements along the surface of the pipe and the wall of the cavity and thus easily reach the lowest point of the cavity in the ground.

Such a geothermal probe assembly is particularly fast and inexpensive to install in the cavity in the ground. In a coaxial probe, elements for spacing the tube from the wall of the cavity in the ground are arranged on the outer tube.

The object of specifying a device for exchanging heat energy with the ground is achieved according to claim 10. In the context of the present invention, a device is provided for exchanging thermal energy with the ground, which has at least one borehole heat exchanger arrangement as described above.

The present invention will be explained in more detail with reference to the accompanying drawings.

This shows

1 shows a schematic cross section through an inventive

Earthwave probe assembly in a cavity in the ground;

Fig. 2 is a schematic plan view in the longitudinal direction of a geothermal probe assembly according to the invention in a cavity in the ground in a partially sectioned view. In Fig. 1 is a schematic cross section through a geothermal probe assembly 1 according to the invention in a cavity 5 in the ground 8 is shown.

In the soil 8, a cavity 5 has been created for this purpose, which was produced for example in a drilling process in which the inventive

Geothermal probe assembly 1 is installed.

The geothermal probe assembly 1 in this case comprises two approximately parallel tubes 2, 2 '. The tube 2 can in the present case, for example, as a flow for in the

Geothermal probe assembly 1 to be used fluid to be used, the pipe 2 then as return. With the help of the geothermal probe assembly 1 flowing through fluid heat energy is exchanged with the ground 8.

For spacing the tubes 2, 2 'from the wall 6 of the cavity 5 and from each other elements 4 in the form of webs on the tubes 2, 2' are arranged.

As can be seen from FIG. 1, four elements 4 in the form of webs are arranged on the tubes 2, 2 'such that the webs have approximately the same height above the tube wall of the tubes 2, 2'.

The webs 4 are about the same complained along the circumference of the tubes 2, 2 'arranged.

In the present case, four webs 4 are provided on the two tubes 2, 2 '.

The webs 4 are used so that the positioning of the geothermal probe assembly 1 in the cavity 5 in the ground 8 is approximately centered, so that the space between the wall 6 of the cavity 5 and the tubes 2, 2 'are filled in a simple manner with the backfill material 7 can.

In particular, the tubes 2, 2 'are spaced apart by the elements 4 serving as spacers to the wall 6 of the cavity 5 in the ground 8.

Since none of the tubes 2, 2 'can directly abut the wall 6 of the cavity 5 in the ground 8, there is a secure filling of the free space between the wall 6 of the cavity 5 in the ground 8 and the tubes 2, 2'.

Thus, on the one hand, a very good thermal connection between the ground 8 and the pipes 2, 2 'can be achieved; furthermore, the free space between the wall 6 of the cavity 5 in the ground 8 and the pipes 2, 2' can be over the entire or approximately the entire length of the cavity 5 in the soil 8 are filled with the backfill material 7, so that individual aquifers (aquifers) can be safely separated from each other. In Fig. 1 it is further shown that two elements 4 on the tubes 2, 2 'are aligned such that they assign approximately to each other.

This ensures that the tubes 2, 2 'can not touch each other by the elements 4 functioning as spacers, as a result of which a thermal short circuit between the tubes 2, 2' is reliably avoided, so that no heat energy is unintentionally between the tubes 2, 2 'is replaced.

FIG. 2 shows a schematic longitudinal plan view of a borehole heat exchanger arrangement 1 according to the invention in a cavity 5 in the ground 8 in a partially sectioned view.

The inventive geothermal probe assembly 1 is installed in a cavity 5 in the ground 8. The cavity 5 in the ground 8 has been produced for this purpose, for example, in a drilling process.

The geothermal probe assembly 1 in this case comprises two tubes 2, 2 ', of which one tube, for example, tube 2, serves as a flow and the other tube, tube 2', as a return for the fluid to be conducted.

The circulating in the geothermal probe assembly 1 fluid exchanges heat energy during operation of the geothermal probe assembly 1 with the ground 8 from. On the tubes 2, 2 'elements 4 are provided, which, as shown in Fig. 2, are formed as webs.

The webs 4 serve to space the tubes 2, 2 'from the wall 6 of the cavity 5 in the ground 8 and from each other.

The webs 4 are formed on the tubes 2, 2 'in sections, wherein they have a longitudinal extent, which extends in the axial direction of the tube.

At the ends of the longitudinal extension of the webs 4 bevels 4.1 are arranged, which serve that the introduction of the geothermal probe assembly 1 in the cavity 5 in the earth floor 8 is facilitated, thereby avoiding that it comes to wedging or jamming.

As can further be seen from FIG. 2, the elements 4 are arranged several times along the circumference of the tubes 2, 2 '.

The inventive geothermal probe assembly 1 allows that the space between the wall 6 of the cavity 5 in the ground 8 and the tubes 2, 2 'in a simple manner can be filled with the backfill material 7, in which it is ensured that none of the tubes. 2 , 2 'on the wall 6 of the cavity 5 in the ground 8 and also does not abut each other, and there possibly prevents the filling or makes it difficult.

Also, the thermal Kuerzschluss between the tubes 2, 2 'is thereby excluded because the tubes 2, 2' are spaced from each other by the elements 4. The filling of the free space can thus be accomplished over the entire length, whereby a very good thermal connection between ground 8 and the pipes 2, 2 'is ensured. By filling the open space with the filling material 7, aquifers in different levels in the soil 8 (aquifers) can be reliably separated from each other.

LIST OF REFERENCE NUMBERS

1 geothermal probe arrangement

2, 2 ^' pipe

4 element

4.1 slope

5 cavity

6 wall

7 backfill material

8 soil

Claims

claims

1. geothermal probe assembly (1) for introduction into a cavity (5) in the ground (8), in which two tubes 2, 2 '), one of which is provided as a supply and the other as return for a fluid flowing through, characterized that at least one element 4 is arranged on at least one tube (2, 2 '), the tube (2, 2') inserted into the cavity (5) in the ground (8) from the wall (6) of the tube

Cavity (5) spaced.

2. geothermal probe assembly (1) according to claim 1, characterized in that the element (4) integral with the at least one tube (2, 2 ') is formed.

3. geothermal probe assembly (1) according to claim 1 or 2, characterized in that the element (4) contains a polymer material or consists of polymer material, wherein the polymer material is preferably made of a polyolefin, more preferably of a polyethylene or a polypropylene or a crosslinked polyethylene - is selected.

4. geothermal probe assembly (1) according to any one of the preceding claims, characterized in that the element (4) has a longitudinal extent and thus along at least part of the length of the tube (2, 2 ') is arranged.

5. geothermal probe assembly (1) according to any one of the preceding claims, characterized in that a plurality of elements (4) are arranged, which are spaced approximately the same along the tube circumference.

6. geothermal probe assembly (1) according to any one of the preceding claims, characterized in that the element (4) as a web, in T-shape, in H-form, in O-form, in V-form, or in a mixed form of the aforementioned Shapes is formed. A geothermal probe arrangement (1) according to one of the preceding claims, characterized in that a bevel (4.1) is formed at at least one end of the longitudinal extension of the element (4),

Geothermal probe assembly (1) according to one of the preceding claims, characterized in that the two tubes (2, 2 ') are arranged as a U-probe, in particular as a double-U probe.

A geothermal probe assembly (1) according to any one of claims 1 to 7, characterized in that the two tubes (2, 2 ') are arranged as a coaxial probe.

Device for exchanging heat energy with the ground (8) with at least one borehole heat exchanger arrangement (1) according to one of Claims 1 to 9.