BACKGROUND OF THE INVENTION

The invention relates to a method for introducing an elongated element, particularly a tube assembly of a geothermal heat exchanger, into a soil. The invention furthermore relates to an arrangement with a geothermal heat exchanger and to a tube assembly, particularly for a geothermal heat exchanger.

It is known to place elongated elements, particularly tube assemblies of geothermal heat exchangers, into a soil by means of the following steps:

- making a bore of the desired depth in the soil by driving a tube provided with a soil displacement and/or soil dislodging/removal head into the soil,

- during making the bore supplying a water/bentonite mixture for discharging the soil material,

- withdrawing the tube,

- introducing the elongated element into the bore filled with the drilling liquid (mixture of said water/bentonite mixture and soil material) until the lower end of the elongated element is at the wanted depth,

- from ground level introducing a grout tube, for filling the bore with flowable, thermally conductive material, such as grout, while urging the drilling liquid out of the bore.

When introducing the grout tube, together with or without the elongated element, the grout tube may engage into the hole wall, as a result of which the grout tube is stopped and/or as a result of which soil material is dislodged, also after passage of the distal end of the grout tube. As a result the introduction process is on the one hand made more difficult, on the other hand soil material is collected in the lower end of the bore. The latter may result in the grout tube getting stuck at the distal end and being difficult to pull up. Also when the tube is left behind problems may arise when introducing the grout tube.

In order to prevent these problems the diameter for the tube to be introduced into the soil is chosen such that the elongated element and the grout tube can be introduced more easily. For instance in case of a 63 mm tube assembly for a geothermal heat exchanger and a 40 mm diameter grout tube, a 140 mm drill tube is taken. Filling the bore thus requires a lot of grout in relation to the diameter of the tube assembly. Thus the distance from the hole wall to the tube assembly is also rather large. In addition a bore of a larger diameter will result in more soil material to be removed and to be discharged. Furthermore the drilling costs and the power to be utilised depend on the diameter.

SUMMARY OF THE INVENTION It is an object of the invention to provide a method of the type mentioned in the preamble with which a fast and/or reliable fill of the bore using flowable, thermally conductive sticking material is possible, the bore being determined by a tube urged into the soil or after removal of the tube by the wall of the hole made in the soil with such a tube.

It is an object of the invention to provide a method of the type mentioned in the preamble with which a high efficiency arrangement of a geothermal heat exchanger can be achieved. It is an object of the invention to provide a method of the type mentioned in the preamble that may be cost-effective.

It is an object of the invention to provide an arrangement of the type mentioned in the preamble including geothermal heat exchanger with which a high efficiency can be achieved. It is an object of the invention to provide a tube assembly with which a fast and/or reliable fill of a bore using flowable, thermally conductive material is possible, the bore being made in the soil by means of a tube that is urged into the soil.

It is an object of the invention to provide a tube assembly with supply conduit for said thermally conductive material, which can relatively easily be introduced into a bore made in the soil. According to one aspect the invention provides a method for from a ground surface introducing an elongated element, particularly a tube assembly of a geothermal heat exchanger, into a soil, wherein a tube, having a soil displacement or soil dislodging/removal head at the distal end, is driven into the soil down to a wanted depth, wherein the elongated element is introduced from the ground surface into the realised bore until the distal end is at the wanted depth, wherein with or following the elongated element a liquid conduit that is deformable in cross-section is introduced into the bore, in a condition of a small cross-section, particularly a flat condition, and wherein particularly after introducing the distal end of the liquid conduit into the bore at the depth wanted for that purpose, thermally conductive flowable material, such as grout or the like, is urged through the liquid conduit while augmenting the cross-section of the liquid conduit and exits from the distal end of the liquid conduit for filling the bore with the thermally conductive flowable material.

By introducing the liquid conduit into the bore in a condition of reduced cross-section, particularly a flat condition, the joint cross-section of elongated element and liquid conduit can remain smaller, as a result of which the diameter of the bore can also remain smaller (in the above- mentioned situation for instance 10 cm), without increasing the risk of dislodging or detaching material in the bore hole wall or the introduction being made difficult. In that way the quantity of soil material to be removed, the quantity of filling material and the costs of making the bore are economised on.

In a simple embodiment the liquid conduit is attached to the elongated element in advance and is introduced into the bore together with the elongated element. The elongated element then acts like a vehicle for the liquid conduit, so that an extra step of introducing the liquid conduit is avoided. As liquid conduit use can be of a hose that can be pressed together in cross-section, preferably a hose that can be folded together flat, and be rolled up in that condition. An example is the hose available under the name of Heliflat ^® -M discharge/pressure hose. In one embodiment the liquid conduit and the elongated element can be supplied to the work, particularly on a roll, as a unit that is already attached to one another.

Alternatively the liquid conduit can be attached to the elongated element prior to introduction, but in situ. In that case the liquid conduit can be supplied to the work separately on a roll and preferably be taken from the roll simultaneously with introducing the elongated element into the bore, wherein the elongated element preferably is supplied to the work on a roll. Preferably the liquid conduit is attached to the elongated element at least near the distal end of the liquid conduit, so that the introduction profile is as small as possible.

' The liquid conduit preferably is attached to the elongated element near the distal end of the elongated element, so that the conduit is thus taken to a location in the bore that is advantageous for filling.

Under conditions attaching the distal end of the liquid conduit to the elongated element only may suffice. Alternatively the liquid conduit can be attached to the elongated element at locations that are spaced apart in longitudinal direction. In that case at least over a length at the location of attachment to the elongated element, the liquid conduit can be placed flat around a part of the outer surface of the elongated element, parallel thereto. The flat liquid conduit then follows the wall shape of the elongated element and can then constitute no more than a relatively small thickening thereof. If during introducing the elongated element the bore is filled with drilling liquid, and the thermally conductive material has a higher specific gravity than the drilling liquid, once the thermally conductive material is introduced into the bore the drilling liquid will be urged out at the top of the bore. By introducing flowable thermally conductive material from below into the bore, the drilling liquid can be gradually taken out of the bore by simple upward displacement. Mixing that would otherwise arise between downwardly flowing thermally conductive material and upwardly displaced drilling liquid is thus prevented to a large extent.

In one embodiment, when introducing the elongated element into the bore, the liquid conduit is attached to the elongated element by means of one or more connections that can be made to fail (failurable), preferably near the distal end of the liquid conduit and/or near the distal end of the elongated element. Due to the failurable connection the liquid conduit is taken along into the tube during introduction of the elongated element, but the connection can be broken after that. The failurable connection used can be arranged for pressing the liquid conduit flat against the elongated element, by engaging its side facing away from the elongated element. The failurable connection can also have a function in initially pressing an open distal end of the liquid conduit closed.

Having the failurable connection fail can for instance take place by means of remote controlled (above ground level) pulling means, such as the liquid conduit itself or a drawstring or pulling cable drawn through the liquid conduit, which pulling means are able to release/terminate a detachable or failurable connection, such as a nail or adhesive connection, with which the distal end of the liquid conduit, particularly its wall situated against the elongated element, is attached to the elongated element.

In one embodiment the failurable connection can be made to fail by augmenting the cross-section of the liquid conduit at that location by increasing the pressure of the thermally conductive material in the liquid conduit, particularly while having a surface of the liquid conduit ascending in proximal direction progress in distal direction. This can take place when filling the liquid conduit under pressure with the thermally conductive flowable material, wherein the conduit in the direction towards its distal end will progressively bulge of the liquid conduit. This can also be done in two steps, first initially filling the conduit, and then at a higher pressure pulse generate an as it were once-only wave motion in the surface of the conduit. The ascending surface is particularly advantageous when the liquid conduit is attached to the elongated element by means of rope or band, such as duct tape, as failurable connection that presses the liquid conduit against the elongated element. Especially duct tape easily ruptures in a direction transverse to tape direction. After the connection has failed the material is able to flow out through the open, distal end of the liquid conduit, in particular hose.

The failurable connection can be disposed around the liquid conduit and elongated element. An advantageous result thereof is that during filling the bore with thermally conductive flowable material the liquid conduit can be withdrawn. As a result the liquid conduit is able to follow the rising upper level of the thermally conductive filler material with the distal end, which enhances the filling process. The deformability of the liquid conduit enhances withdrawal.

Alternatively the distal end of the liquid conduit can be held near the distal end of the elongated element during discharging the thermally conductive flowable material. In one embodiment the tube urged into the soil can be withdrawn from the bore during filling the bore with the thermally conductive flowable material.

Alternatively the tube urged into the soil can already be withdrawn from the bore prior to filling the bore with the thermally conductive flowable material, as already stated above.

In one embodiment the liquid conduit is situated eccentrically at the exterior side of the elongated element. During acquiring the circular cross-section the liquid conduit can urge the elongated element to an eccentric position in the bore, particularly press it into abutment with the wall of the bore. In that way under certain conditions the thermal transmission at that location between heat exchanger and soil material can be enhanced. For geothermal applications, the elongated element can comprise a coaxial tube assembly, having an inner flow passage and an annular outer flow passage that is concentric therewith, wherein the distal end comprises a cap in which the inner flow passage is connected to the outer flow passage.

According to a further aspect the invention provides a method for from a ground surface introducing an elongated element, particularly a tube assembly of a geothermal heat exchanger, into a soil, wherein a tube, having a displacement or dislodging/removal head at the distal end, is driven into the soil down to a wanted depth for making a bore, wherein, after withdrawal or not of at least the tube from the soil, the tube assembly is introduced from the ground surface into the realised bore, wherein after the distal end of the tube assembly has been introduced at the wanted depth in the bore, the tube assembly is urged to an eccentric position with respect to the bore, preferably is pressed into abutment with the wall of the bore, and the bore is filled with thermally conductive flowable material, such as grout or the like. In that way with or following the tube assembly a liquid conduit in flat condition can be introduced along into the bore and after introducing the distal end of the tube assembly at the wanted depth in the bore, the thermally conductive flowable material can be passed through the liquid conduit which as a result will expand while pressing the tube assembly to the bore wall. The flowable material then will continue to be supplied for exiting from the distal end of the liquid conduit to fill the bore with the thermally conductive flowable material. The aspects according to the invention of the liquid conduit discussed above can also be applicable here. If the bore does not extend vertically it may be advantageous to press the tube assembly against the upper wall section of the bore as then the material at that location of the bore wall is retained additionally.

According to a further aspect the invention provides an arrangement of a tube assembly for a geothermal heat exchanger in a bore made for that purpose in a soil, wherein a thermally conductive mass is present in the space between the tube assembly and the bore wall, wherein the tube assembly is situated eccentrically in the bore over at least almost the full length, preferably abutting the bore wall on one side. In a first embodiment the bore wall is defined by a permanent tube. In a second embodiment the bore wall is defined by the soil material. As discussed above the elongated element can comprise a coaxial tube assembly, having an inner flow passage and an annular outer flow passage that is concentric therewith, wherein the distal end comprises a cap in which the inner flow passage is connected to the outer flow passage. According to a further aspect the invention provides a coaxial tube assembly for a geothermal heat exchanger, having an outer tube and an inner tube, wherein the inner tube defines an inner flow passage and the inner tube and outer tube define an annular outer flow passage that is concentric therewith, wherein the distal end of the tube assembly comprises a cap in which the inner flow passage is connected to the outer flow passage, wherein on the outer tube, preferably one-sided, an added supply conduit for fluid is disposed. The supply conduit preferably has a flat condition and under internal pressure is expandable into a round condition. By means of a failurable connection, as discussed above, the supply conduit can be connected to the outer tube, preferably near the distal end of the supply conduit and/or near the distal end of the outer tube.

According to a further aspect the invention provides a method for from a ground surface introducing an elongated element, particularly a tube assembly of a geothermal heat exchanger, into a soil, wherein a tube, having a soil displacement or soil dislodging/removal head at the distal end, is driven into the soil down to a wanted depth wherein, whether or not after withdrawal of at least the tube from the soil, the elongated element is introduced from the ground surface into the realised bore, wherein with the elongated element a liquid conduit provided with a flexible wall, particularly in flat condition is introduced along into the bore, and wherein after introducing the distal end of the elongated element at the wanted depth in the bore, thermally conductive flowable material, such as grout or the like, is passed through the liquid conduit and exits from the distal end of the liquid conduit for filling the bore with the thermally conductive flowable material. According to a further aspect the invention provides a method for from a ground surface introducing an elongated element, particularly a tube assembly of a geothermal heat exchanger, into a soil, wherein a drill pipe having a drill head at the distal end, is driven into the soil down to a wanted depth, wherein the elongated element is introduced from the ground surface into the realised bore with the distal end down to the wanted depth, wherein with or following the elongated element a liquid conduit that is deformable in cross-section, in a condition of a small cross-section, particularly a flat condition, is introduced into the bore, and wherein, particularly after introducing the distal end of the liquid conduit at the wanted depth in the bore, thermally conductive flowable material, such as grout or the like, is urged through the liquid conduit while augmenting the cross-section of the liquid conduit and exits from the distal end of the liquid conduit for filling the bore with the thermally conductive flowable material. This method may furthermore comprise one or more of the steps according to any one of the attached claims 1-22.

The aspects and measures described in this description and the claims of the application and/or shown in the drawings of this application may where possible also be used individually. Said individual aspects may be the subject of divisional patent applications relating thereto. This particularly applies to the measures and aspects that are described per se in the sub claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which:

Figures 1-4 show a few steps in an exemplary embodiment of a method according to the invention, with cross-sections A-A at the top;

Figure 5 shows a schematic view of an exemplary embodiment of an arrangement according to the invention; Figure 6 shows a schematic view of a tube assembly according to the invention;

Figures 7A-C schematically show a number of stages in filling and opening a supply conduit on a tube assembly according to the invention; and

Figure 8 shows a schematic view of a possible way of introducing a tube assembly with supply conduit according to the invention. DETAILED DESCRIPTION OF THE DRAWINGS

In figures 1-4 a soil 100 is shown, having a top surface or ground level 101. In the soil 100 a bore 102 has previously been made by means of urging a tube provided with a tip into the soil, after which the tube was retracted. This may have taken place by means of drilling, ramming, vibrating or pressing or another suitable manner given the circumstances. The bore 102 is filled with drilling liquid 104, a mixture of soil material and bentonite/water mixture having a specific gravity of a little over 1. The bore 102 made has a wall 103.

In figure 1 a tube assembly 1 , also see figure 6, in which the tube assembly 1 is shown schematically on a roll 40, is passed in the direction B into the bore 102. This can for instance be done by providing its lower end 8 with a weight or by exerting a pushing force onto the circumference of the tube assembly 1 or by driving a reel on which the tube assembly 1 has been supplied. The tube assembly 1 is meant as geothermal heat exchanger and comprises a coaxial tube set, namely an outer tube 2 of thermally conductive synthetic material, for instance an HDPE, having a diameter of 63 mm, and an inner tube 3 of synthetic foamed material with closed cells, for instance a polyethene. The inner tube 3 has two integrally formed ribs 6, among others for centring the inner tube 3 in the outer tube 2. Thus an annular flow passage 4 and flow passage 5 situated within it is formed. A heat exchanger fluid, particularly liquid, more particularly water, is able to flow downwards through the one passage and upwards through the other, wherein reversal takes place in the end cap 7 at the distal end of the tube assembly. Against the exterior side of the outer tube 2 a hose 10 having a flexible wall 11 (for instance of polyester or polyethene, and for instance having a wall thickness of 1-2 mm) has been arranged (one-sided). A suitable hose that can be folded together flat and can be rolled up (in the manner of a fire hose) is the hose available under the name of Heliflat ^® -M discharge/pressure hose, for instance having a cross-section of 38 mm, having an operational pressure of up to 10 bars.

At the distal end 10a the hose 10 is open, yet in the vicinity thereof by means of a failurable connection, here schematically shown with a breakable string 12 (for instance 4 mm nylon), temporarily secured on the outer tube 2, wherein the string is laid around the hose and the outer tube 2. An alternative is for instance a tape (duct tape), particularly a tape that ruptures transverse to its length. Said tape is then also wrapped around the hose (pressed flat at that location) and outer tube, see figures 7A-C.

In figure 2 the hose 10 is filled from above with a flowable thermally conductive material 20 introduced into the hose 10 under pressure (for instance in the range of 1.5-4 bars, depending on the conditions, such as depth of bore), the material for instance being grout having a coefficient of heat conduction of over 0.7, preferably over 2.5. The material 20 under pressure has the hose 10 progressively expand in distal direction, also see figures 7A-C, wherein at the location of the progressing transition between flat condition and filled condition a progressing (direction H) inclined surface 10' is formed.

As the hose 10 expands, arrows C in figure 2A, during filling the hose 10, it will end up against the bore wall 103 and the tube assembly 1 is pressed against the bore wall 103 in the direction D.

The filling pressure can be set so high that the connection 12 fails at the filling pressure after the hose has been filled, see figure 7. Alternatively by increasing the filling pressure of the hose 10, particularly by means of a pressure pulse, in this example for instance 5-6 bars, it can be ensured that the connection 12 fails. In figures 7A-C it is shown that due to the bulge or inclination 10' being under pressure the duct tape 12 will start to rupture, in transverse direction at the location of the bridging between hose wall and outer tube wall 2, see ruptures 12', until a continuous rupture 12" has been formed over the entire connection 12 and the hose 10 is detached from the outer tube 2 on one side. The open distal end 10a of the hose 10 is then free (figure 7A) and is able to open. The fiowable material 20 flows, direction E (also figure 3), from the distal hose end 10a and starts filling the bore 102. As the material 20 is much heavier (specific gravity of 1.5 or more) than the drilling liquid 104 the drilling liquid 104 is urged upwards and the level of the material 20 rises (direction F). The drilling liquid 104 exits the bore 102 at ground level 101 , direction G. When its is suspected that the level of the material 20 has reached the distal hose end 10a the hose 10 is pulled up (direction H, figure 4) in register with the rise of the level of material 20. The bore 102 will thus be filled more and more with material 20, that urges the drilling liquid 204 out of the bore 201. The deformable cross-section of the hose 10 enhances the retrieval of the hose.

Finally the entire bore 102 is filled with the thermally conductive material 20, wherein the tube assembly 1 is held eccentrically in the bore, see figure 5, wherein the centre line S of bore 102 and centre line T of the tube assembly 1 have been indicated. The bore 102 is closed off at the top by means of a cap 30. At the top the tube assembly 1 is provided with a splitter cap 31 , with a connecting spout 31a for a supply conduit of heat exchanger fluid to the inner tube 3 and a connecting spout 31b for a discharge conduit of the heat exchanger fluid coming from the annular space 5.

In the embodiment of figure 6 the hose 10 is already attached to the tube assembly 1 in advance and in that condition, supplied to the work on a roll. It is also possible, see figure 8, to supply the hose separately on a roll 50 and shortly before starting to introduce the tube assembly 1 attaching the hose to the tube assembly 1 at the wanted location, especially near its distal introduction end, by means of a failurable connection 12. This can be repeated regularly, for instance every few meters, during the introduction, or suffice with the first connection 12 only. The failurable connections can fail one after the other as the inclination 10' progresses during filling the hose. The above description is included to illustrate the operation of preferred embodiments of the invention and not to limit the scope of the invention. Starting from the above explanation many variations that fall within the spirit and scope of the present invention will be evident to an expert.