TWISTED CONDUIT FOR GEOTHERMAL HEAT EXCHANGE

Abstract

A geothermal heat exchange apparatus is disclosed that comprises a flexible assembly of a plurality of pipes twisted on a central conduit. The central conduit has a tubular structure. The plurality of pipes is twisted around the central conduit. The plurality of pipes is adapted to connect to an external environmental control system that supplies a heat exchange liquid for the transfer of heat through the plurality of pipes. The geothermal heat exchange apparatus is adapted for positioning in a hole in the earth for the exchange of heat.

Claims

1. A plurality of pipes in twisted arrangement for geothermal heat exchange, the arrangement of pipes comprises: a central conduit having a first diameter, the central pipe has a first end portion and an opposed second end portion, the central conduit flexible; and a plurality of pipes, each pipe of the plurality of pipes has a first end portion and an opposed second end portion, each pipe of the plurality of pipes is flexible, the plurality of pipes twisted around the central conduit in an approximately parallel arrangement, the plurality of pipes positioned in direct contact with the central conduit and each pipe of the plurality of pipes positioned in an approximately fixed spaced separation that defines a gap between adjacent pipes of the plurality of pipes, the second end portion of each pipe of the plurality of pipes connected by a joint, the arrangement of the plurality of pipes flexible and coilable into a roll, the first end portion of each pipe of the plurality of pipes adapted to connect to an external environmental control system.

2. The multipipe twisted arrangement of claim 1, wherein the external environmental control system at least includes at least one of heating or cooling.

3. The multipipe twisted arrangement of claim 1, wherein the first end portion of a first set of pipes connects to a first manifold that receives inflow to the first set of pipes and a second set of pipes connects to a second manifold that receives outflow from the second set of pipes, the first set of pipes and the second set of pipes comprise the plurality of pipes, the manifold adapted to connect to the external environmental control system.

4. The multipipe twisted arrangement of claim 1, wherein the joint receives and redirects the flow from a first set of pipes of the plurality of pipes to at least one outflow pipe, the first set of pipes and the at least one outflow pipe comprise, the plurality of pipes.

5. The multipipe twisted arrangement of claim 1, wherein the joint is a manifold and the manifold defines a reservoir therein, the manifold receives the flow from a first set of pipes of the plurality of pipes and directs the flow into the reservoir and redirects the flow from the reservoir into a second end portion of an at least one outflow pipe, the first set of pipes and the at least one outflow pipe comprise the plurality of pipes.

6. The multipipe twisted arrangement of claim 1, wherein the joint is a manifold and the manifold defines a reservoir therein, the manifold receives the flow from a first set of pipes of the plurality of pipes that is at least one pipe and directs the flow into the reservoir and redirects the flow from the reservoir into a second end portion of a second set of multiple outflow pipes, the at least one first set of pipes and the plurality of outflow pipes comprise the plurality of pipes.

7. The multipipe twisted arrangement of claim 1, wherein the multipipe arrangement further includes bands transverse to the longitudinal axis of the multipipe arrangement.

8. The multipipe arrangement of claim 1, wherein the center pipe is a through pipe that defines a first aperture in the first end portion and a second aperture in the second end portion.

9. The multipipe twisted arrangement of claim 1, wherein the plurality of pipes is held in the twisted arrangement against the central pipe by at least one joint and at least one manifold, the at least one manifold is connected to the first end portion of each pipe, of the plurality of pipes and the at least one joint is connected to the second end portion of each pipe of the plurality of pipes.

10. The multipipe twisted arrangement of claim 1, wherein the plurality of pipes is held in the twisted and spaced arrangement against the central pipe by at least one joint and at least one manifold, the at least one manifold is connected to the first end portion of each pipe of the plurality of pipes and the at least one joint is connected to the second end portion of each pipe of the plurality of pipes.

11. The multipipe twisted arrangement of claim 1, wherein the plurality of pipes includes at least one pair of pipes, the second end portion of each pipe of the at least one pair of pipes connect to the joint and the joint is a U-bend.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a perspective view of an idealized prior art environmental control system that uses a single conduit for geothermal heat exchange;

[0021] FIG. 2 is a perspective view of the geothermal heat exchange apparatus of the present disclosure;

[0022] FIG. 3 is a partial cut-away perspective view of the geothermal heat exchange apparatus of FIG. 2;

[0023] FIG. 4 is a cross-section taken along lines 4-4 of the geothermal heat exchange apparatus of FIG. 3;

[0024] FIG. 5 is a perspective view of the geothermal heat exchange apparatus of FIG. 2 coiled into a roll;

[0025] FIG. 6 is a side perspective view of the geothermal heat exchange apparatus of FIG. 2 positioned in a borehole in the earth, a source of grout connected to the geothermal heat exchange apparatus;

[0026] FIG. 7 is a side perspective view of the geothermal heat exchange apparatus of FIG. 6 positioned and grouted in the borehole; and

[0027] FIG. 8 is a cross-sectional taken along lines 8-8 of FIG. 7 showing the grout filling the borehole, around the plurality of pipes and the center conduit.

DETAILED DESCRIPTION OF THE INVENTION

[0028] Referring initially to FIG. 2, a geothermal heat exchange apparatus 10 includes a center conduit 12 and a plurality of pipes 14. The plurality of pipes 14 is positioned in a twisted arrangement on center conduit 12. Geothermal heat exchange apparatus 10 defines a first longitudinal axis-X aligned with a centerline of central conduit 12.

[0029] Center conduit or conduit 12 has a flexible tubular structure that includes a first end portion 16 and an opposed second end portion 18. The tubular wall of conduit 12 defines an aperture 20 that is a through hole that extends between first end portion 16 and second end portion 18. Aperture 20 has a first inside diameter. In one preferred embodiment, the corrugated center conduit 12 dimensions include an inside diameter of approximately 1.9 inches, outside diameter of approximately 2.375 inches and a wall thickness of approximately 1/16.sup.th or 0.0625 inches. It is understood that the size of the inside diameter can vary depending upon the intended geothermal heat exchange application.

[0030] As shown in FIGS. 2 and 3, geothermal heat exchange apparatus 10 has an approximately tubular overall structure defined by through hole 20 of the center conduit 12 and the twisting arrangement of the plurality of pipes 14 around central conduit 12. Plurality of pipes 14 has a flexible tubular structure that includes a first end portion 22 and an opposed second end portion 24. Each pipe 15 of the plurality of pipes 14 is a conduit that defines an aperture 26 that is a through hole that extends between the first end portion 22 and the second end portion 24. Aperture 26 of each pipe 15 of the plurality of pipes 14 is shown as having a relatively small diameter relative to center conduit 12, but the size of each pipe 15 and the corresponding aperture 26 of each pipe 15 of the plurality of pipes 14 can vary depending upon the intended application. In one preferred embodiment, individual pipes 15 of the plurality pipes 14 are standard % or 0.75 inch inside diameter of pipes 15 with a wall thickness of approximately 0.078 inch. The size of each pipe 15 of the plurality of pipes 14 is varied to accommodate the liquid flow and/or cooling demand for a given application.

[0031] As shown in FIG. 2, the first end portions 22 of the inflow pipes 14A of the plurality of pipes 14 connect to at least one manifold 28. In one preferred embodiment, first end portions 22 of inflow pipes 14A of first manifold 28 connect to a first manifold 28 and the first end portions 22 of the outflow pipes 14B of the plurality of pipes 14 connect to a second manifold 28. It is understood that the number of manifolds 28 can vary depending upon the intended geothermal heat exchange application. Geothermal heat exchange apparatus 10 can optionally include one or more manifolds that are connected in the field either before or after installation in the borehole. Alternatively, manifolds 28 can be connected the plurality of pipes in a controlled setting during the assembly of geothermal heat exchange apparatus 10.

[0032] Each pipe 15 of the plurality of pipes 14 is twisted onto and preferably around the central conduit or conduit 12 in a parallel, spaced and twisted arrangement. Twisted onto as defined herein includes directly positioning the plurality of pipes 14 in direct contact with central conduit 12 in an arcuate arrangement. In the preferred embodiment the plurality of pipes 14 is positioned in an approximately parallel spaced helical arrangement around the central conduit 12. Each pipe 15 of the plurality of pipes 14 is approximately in direct contact with central conduit 12. Each pipe 15 of the plurality of pipes 14 is positioned in approximately fixed spaced separation on center conduit 12 relative to the adjacent pipe 15 of the plurality of pipes 14.

[0033] The plurality of pipes 14 is a multipipe or multiple pipe twisted arrangement of the plurality of pipes 14 around center conduit 12. Individual pipes 15 of the plurality of pipes 14 can vary in their respective inside diameters, the quantity of pipes 15 in the plurality of pipes 14 and the arrangement of pipes 15 on center conduit 12 depending upon the intended application of geothermal heat exchange apparatus 10. For example, in one preferred embodiment, there are a total of eight (8) pipes 15 in a twisted arrangement around the conduit 12. The second end portion 24 of each pipe 15 of the plurality of pipes 14 connects to a joint 30 to define four (4) pairs of pipes 15 with each pair of pipes 15 connected by one joint 30. In this one preferred embodiment, joint 30 is a U-bend that receives the downwardly directed inflow from a first pipe 15 of a first set of pipes 14A and redirects the flow upwardly into a second pipe 15 of a second set of pipes 14B connected to manifold 28 in this one example.

[0034] Other arrangements the plurality of pipes 14 and joint 30 include, for example, three (3) pairs of pipes 15 with each pair of pipes 15 connected by one joint 30. Additional arrangements include joint 30 having a manifold type structure that connects to the second end portions of the first set of pipes 14A and to the second end portion of the second set of pipes 14B that includes at least one pipe 15. Thus, joint 30 can for example receive the flow input from first set of pipes 14A that is four (4) pipes 15 and redirect that flow into the second set of pipes 14B that is the same or a different quantity of pipes 15 than first set of pipes 14A. As another example, in one preferred embodiment, joint 30 receives the input flow of four (4) pipes 15 with an inside diameter of approximately 0.8 inches that is the first set of pipes 14A and redirects and realigns that flow in to joint 30 to the second set of pipes 14B that is a single pipe 15 with an inside diameter of approximately 1.6 inches. Similarly, the first set of pipes 14A of the plurality of pipes 14 for inflow can be a single pipe 15 and the second set of pipes 14B for outflow can be multiple pipes 15.

[0035] Center conduit 12 preferably has a length that is less than that of the plurality of pipes 14 in order to accommodate the central positioning of one or more joints 30 within the compact diameter of geothermal heat exchange apparatus 10. In one preferred embodiment, the plurality of pipes 14 and/or one or more joints 30 extend past conduit 12. Center conduit 12 can be any shape of tubular conduit, but preferably has a circular cross-section perpendicular to the longitudinal axis. In addition, conduit 12 can have a structure that facilitates flexing and reduces the minimum bend radius for applications such as, for example, coiling into a roll. These structures of the tubular wall of conduit 12 can include, but are not limited to undulations in any form to include corrugations 36 that retain the approximately continuous inside diameter during flexing.

[0036] Plurality of pipes 14 is preferably positioned on central conduit 12 in a twisted arrangement. In addition, each pipe 15 of the plurality of pipes 14 is positioned in an approximately fixed spaced separation with other pipes 15 in the plurality of pipes 14. A space or gap 32 is defined by the fixed spaced separation between each pipe 15 of the plurality of pipes 14.

[0037] Geothermal heat exchange apparatus 10 can further include one or more bands 34 around the twisted plurality of pipes 14 on center conduit 12. Bands 34 can optionally assist in fixing the spacing between each pipe 15 of the plurality of pipes 14. Bands 34 are preferably tape, but can be any type of structural band that assists in the retention of the spaced separation between each pipe 15 of the plurality of pipes 14. In the preferred embodiment, bands 34 are positioned approximately every four feet along the length of the plurality of pipes 14, but it is understood that this can vary with the size of each pipe 15 and size of the plurality of pipes 14 overall.

[0038] Center conduit 12 can have a solid tubular wall, but the tubular wall of conduit 12 preferably defines a plurality of apertures 38. The shape of apertures 38 is shown as being circular, but it is understood that apertures 38 can have any shape and/or directional alignment suitable for the flow of grout from conduit 12 through apertures 38.

[0039] As shown in FIG. 4, the plurality of pipes 14 is in direct contact with central conduit in this one preferred embodiment. Each pipe 15 of plurality of pipes 14 is separated by gap or space 32 defined between adjacent pipes 15 of the plurality of pipes 14. The plurality of pipes 14 is twisted such that it is tight bound to center conduit 12. Band 34 can optionally augment the retention of the plurality of pipes 14 in fixed spaced separation.

[0040] Referring now to FIG. 5, the geothermal heat exchange apparatus 10 is structured for flexibility that includes the bending and coiling of assembled plurality of pipes 14 in the assembled twisted preferably helical arrangement around flexible center conduit 12. Geothermal heat exchange apparatus 10 can also be readily uncoiled into a linear alignment. This flexibility and compactness makes the geothermal heat exchange apparatus 10 easy to store, transport and install. Once uncoiled, the linearly extended assembly 10 can be readily installed down a borehole. The plurality of pipes 14 can have one or more joints 30 installed while coiled as well as one or more manifolds 28. The combination of manifolds 28 and joints 30 connected to the first end portion 22 and second end portion 24, respectively of the plurality of pipes 14 can be used to retain the plurality of pipes 14 in direct contact with conduit 12 and retain the desired separation between individual pipes 15 of the plurality of pipes 14 without the need for bands 34.

[0041] As shown in FIGS. 5 and 6, geothermal heat exchange apparatus 10 has been extended from the coiled position to a linear position in an approximately vertical borehole 6 in the ground. It is understood that borehole 6 is not required to be vertical and can be angled from the vertical. Once positioned in borehole 6, an external source of grout 9 is used to supply grout 40 into center conduit 12 aperture 20 in first end portion 16. Grout 40 is preferably pumped under pressure down conduit 12 and out through aperture 20 in the second end portion 18. Grout 40 surrounds the geothermal heat exchange apparatus 10 in borehole 6 through the primary loading of the grout at the bottom of the borehole and filling the borehole 6 vertically upward as is common practice. In addition, grout 40 advantageously passes through apertures 38 in the tubular wall of conduit 12 in order to provide grout 40 transverse to the longitudinal axis in order to properly fill the spaces 32 between the pipes 15 of the plurality of pipes 14 in approximately fixed spaced separation. As required for a given application, bands 34 can be applied around the plurality of pipes 14.

[0042] The relatively thin walled structure of central conduit 12 and each pipe 15 of the plurality of pipes 15 of geothermal heat exchange apparatus 10 that facilitates coiling also advantageously provides less thermal resistivity and correspondingly better heat transfer when the geothermal heat exchange apparatus 10 is installed in the earth or ground 6.

[0043] Referring now to FIG. 7, grout 40 fills center conduit 12 and surrounds geothermal heat exchange apparatus 10 in borehole 6 to include filling spaces 32. Geothermal heating exchange apparatus 10 has an advantageous level of heat transfer due to the helical twist in the plurality of pipes 14 and the creation of secondary effects in the fluid flow in the plurality of pipes 14. Secondary effects occurs in curved pipes 15 as the laminate flow against the boundary layer on the inside of each pipe 15 becomes a cross flow between the inner and outer pressure gradients experienced by the heat exchange fluid in the plurality of pipes 14. The secondary flow results in elevated levels of heat transfer at relatively low Reynolds numbers in the range of 1,000 or less without the high turbulence and greater pump pressure demands required by straight pipes to achieve the approximately same level of heat transfer at Reynolds number in the range of approximately 2,500—approximately 3,000. Further, the combination of multiple relatively small diameter plurality of pipes 14 provides for increased surface area for heat transfer.

[0044] In the preceding specification, the present disclosure has been described with reference to specific exemplary embodiments thereof. It will be evident, however, that various modifications, combinations and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims that follow. While the present disclosure is described in terms of a series of embodiments, the present disclosure can combine one or more novel features of the different embodiments. The specification and drawings are accordingly to be regarded in an illustrative manner rather than a restrictive sense.