SE1451235A1

SE1451235A1 - Polymer distribution pipe for a geothermal heat pump system

Info

Publication number: SE1451235A1
Application number: SE1451235A
Authority: SE
Inventors: Heimo Ojala; Juha Ojala; Kari Ojala; Mika Ojala
Original assignee: Muovitech Ab
Priority date: 2014-10-15
Filing date: 2014-10-15
Publication date: 2016-04-16
Also published as: WO2016060601A1

Abstract

A polymer distribution pipe (10) for a geothermal heat pump system. The polymer distribution pipe (10) comprising a main pipe (11) adapted to be connected to a geothermal heat pump. The main pipe has a continuous lateral surface (LS) and a length axis (LI) and a main cross-sectional area (Al) being perpendicular to the length axis (LI). The polymer distribution pipe further comprises at least a first and a second connection pipe (13A;13B), integrated in, and extending from, the continuous lateral surface (LS) of the main pipe (11). The first connection pipe (13A) has a length axis (L2) extending in the center of the first connection pipe (13A) and a cross-sectional area (A2) perpendicular to the length axis (L2), which is smaller than the main cross sectional area (Al) of the main pipe (11). The second connection pipe (13B) has a length axis (L3) extending in the center of the second connection pipe (13B) and a cross-sectional area perpendicular to the length axis (L3) of the second connection pipe (13B), which is smaller than the main cross sectional area (Al) of the main pipe (11).(Fig. 2)

Description

POLYl\/IER DISTRIBUTION PIPE FOR A GEOTHERl\/IAL HEAT PUl\/IP SYSTEl\/l TECHNICAL FIELD

[001] The present application relates to geothermal heat pump systemsincluding geothermal pipe collectors and more specifically to polymerdistribution pipes and manifold chambers for improving the connections between a geothermal heat pump and geothermal pipe collectors.

BACKGROUND

[002] Geothermal energy is energy stored as heat in the ground. This energy mayoriginate from the hot core of the earth or may be heat generated by the earth surfacebeing exposed to infrared radiation from the sun. I\/|ost geothermal installations todayuse the second category of geothermal energy, i.e. solar energy stored as heat in e.g. water, ground or bedrock.

[003] ln a geothermal energy system using circulating fluid, the heat is extracted fromthe ground (e.g. water or bedrock) using a geothermal pipe collector. ln the geothermalpipe collector, the fluid, known as heat transfer medium or heat transfer liquid iscirculated such that fluid heated by the geothermal energy is extracted in one end of thegeothermal pipe collector, the cooled fluid is then returned in the other end of the geothermal pipe collector such that a closed system is created.

[004] Examples of geothermal energy systems are ground surface heat systems, seaheat systems and borehole heat systems. ln ground surface heat systems, a severalhundred meter long geothermal pipe collector is buried in the ground at a frostproofdepth. ln a sea heat system, a similar pipe collector is placed in the sea water and/or on/in the sea bed.

[005] ln a borehole system having a plurality of bore holes, a geothermal pipe collectorhaving two fluid conduits is placed in each the bore holes. The geothermal pipecollectors are connected to each other such that a fluid system of several pipe collectors are created, in which a heat transportation medium can be circulated.

[006] Connecting a plurality of collectors makes it possible to extract heat from a plurality of bore holes with the use of a single heat pump. However, the drawback is thata single leak will affect the entire system, and also be much more difficult to locate. Theconnecting of collectors typically requires that the pipes are welded together, whichsometimes needs to be done at the bore hole site. lt would therefore be advantageousto have a geothermal heat pump system in which it is easier to locate and repair leaks, without introducing more joints that risk causing the leaks.

SUMMARY

[007] A polymer distribution pipe for a geothermal heat pump system is provided.The polymer distribution pipe comprises a main pipe adapted to be connected to ageothermal heat pump. The main pipe has a continuous |atera| surface and a length axisand a main cross-sectional area being perpendicular to the length axis. The polymerdistribution pipe further comprises at least a first and a second connection pipe,integrated in, and extending from, the continuous |atera| surface of the main pipe, suchthat the continuous |atera| surface of the main pipe forms a closed base ofthe first andsecond connection pipes. The first connection pipe has a length axis extending in thecenter of the first connection pipe and a cross-sectional area perpendicular to the lengthaxis, which is smaller than the main cross sectional area ofthe main pipe. The secondconnection pipe has a length axis extending in the center of the second connection pipeand a cross-sectional area perpendicular to the length axis ofthe second connection pipe, which is smaller than the main cross sectional area of the main pipe.

[008] One advantage with the main pipe having a continuous |atera| surface until ahole is created for the connection of a geothermal collector in the base a connectionpipe, the amount ofjoints at which leakage could occur is kept at a minimum, theprocess of connecting the geothermal collectors to the connecting tubes are facilitated as well as the process of adding additional collectors to the system.

[009] According to one embodiment, the first and second connection pipes arecylindrical.[01 O] According to one embodiment, each ofthe first and second connection pipes has a substantially flat base which facilitates the process of creating a hole in the base.

[011] According to one embodiment, the substantially flat bases of the first andsecond connection pipes are integrated in the continuous |atera| surface of the main pipe, which again creates less joints and thus less risk of leakage.

[012] According to one embodiment, at least one ofthe main cross-sectional area and the cross-sectional areas of the first and second connection pipes, are circular.

[013] According to one embodiment, the polymer distribution pipe comprisespolyethylene (PE), which is resistant against degradation by the environment of the ground. For the purpose of increasing the outdoor stability and in particular the UVresistance of the PE, Carbon black may be added to the material of the polymerdistribution pipe. According to one embodiment, the polymer material of the distribution pipe comprises between 0,5% and 3% carbon black.

[014] A method of connecting a heat pump to a plurality of geothermal collectorsusing the polymer distribution pipe according to any one of the previous embodiments isfurther provided. The method comprises creating a through-hole in the lateral surface ofthe main pipe, within the lateral surface ofthe first or second connection pipe, such thata fluid connection between the lumen of the main pipe and the first or secondconnection pipe is created. The method further comprises mounting a first end of a valveon the connection pipe having a fluid connection with the main pipe and connecting themain pipe of the polymer distribution pipe to an in or outflow pipe adapted to transporta heat transportation medium from the heat pump, and connecting a second end of thevalve to a geothermal collector, such that a controllable fluid connection between the collector and the heat pump is created.

[015] According to one embodiment ofthe method of installing the polymerdistribution pipe, the step of connecting the second end of the valve to a geothermal collector may be performed in a manifold chamber.

[016] A manifold Chamber for a geothermal heat pump system comprising the polymer distribution pipe according to any one of the previous claims is further provided.

[017] Please note that the embodiments described herein can be combined in any way unless c|ear|y contradictory.

BRIEF DESCRIPTION OF DRAWINGS

[018] The invention is now described, by way of example, with reference to the accompanying drawing, in which:

[019] Fig. la shows a polymer distribution pipe in a plain top view,

[020] Fig. lb shows the polymer distribution pipe of fig. la in a plain side view,

[021] Fig. lc shows section A-A of the polymer distribution pipe of fig. la,

[022] Fig. 2 shows a polymer distribution pipe when installed in a manifold chamber and connected to a geothermal heat pump system.

DETAILED DESCRIPTION

[023] ln the following, a detailed description of embodiments ofthe invention will begiven with reference to the accompanying drawings. Please note that the same referencenumerals refer the same or similar features in the different drawings. lt will beappreciated that the drawings are for illustration only and are not in any way restrictingthe scope of the invention. Thus, any references to directions, such as ”up” or ”down”, are only referring to the directions shown in the figures.

[024] Geothermal energy is to be understood as energy stored as heat in the ground.The energy may originate from the hot core of the earth or may be heat generated by the earth surface being exposed to infrared radiation from the sun.

[025] A geothermal heat pump system is to be understood as any system comprisingmeans for collecting heat from the ground, and extracting that heat using a heat pump.The geothermal heat pump system could for example be a ground surface heat systems,a sea heat systems or a borehole heat systems and the geothermal collector could forexample be a U-pipe collector comprising a separate, closed pipe which is bent such thatit forms a U-shape, or a coaxial collector in which an inner pipe is arranged in an outer pipe.

[026] A polymer distribution pipe, i.e. a distribution pipe made from a polymer material,for a geothermal heat pump system is provided. The polymer distribution pipe is adaptedto distribute the flow of a heat transportation medium from a main pipe, in direct orindirect fluid connection with a heat pump, to a plurality of geothermal collectors. Thepolymer distribution pipe enables a plurality of collectors to be connected at a single location, which enable control and maintenance of the collectors to be performed at a single location.

[027] The polymer distribution pipe according to one embodiment comprises a main pipe adapted to be connected to the inflow or outflow of a heat transportation mediumfrom a heat pump. The main pipe of the polymer distribution pipe has a continuous|atera| surface, meaning that there are initially no ho|es in the |atera| wall of the mainpipe. The polymer distribution pipe further comprises a plurality of connection pipesintegrated in, and extending from the outer |atera| surface ofthe main pipe, such thatthe continuous |atera| surface of the main pipe forms a closed base ofthe first andsecond connection pipes. The plurality of connection pipes are adapted to be connectedto a plurality of geothermal collectors, directly or indirectly (e.g. via a valve). Prior to theconnection of the plurality of collectors to the connection pipes, ho|es are drilled ormilled in the bottom (or base) of the connection pipes, penetrating the continuous|atera| surface of the main pipe such that a fluid connection is established between thelumen inside of the main pipe and the inside ofthe connection pipe. When thegeothermal collector is connected to the connection pipe, the hole establishes a fluidconnection between the geothermal collector and the lumen of the main pipe, which inturn is connected to the heat pump. As the connection pipes remain closed until the holeis created in the bottom (or base) of the connection pipes (by the |atera| surface ofthemain pipe being continuous), the amount ofjoints at which leakage could occur is kept at a minimum.

[028] The polymer distribution pipe is according to one embodiment manufactured bymeans of injection molding, and as such is created from a single piece of material, whichfurther reduces the number ofjoints in the polymer distribution pipe and thus the risk ofleaks. The process of injection molding also enables the flat base of the cylindricalconnection pipe to be created without making the wall ofthe main pipe any thinner, as material can be added to make the flat base.

[029] Fig. 1 shows a polymer distribution pipe 10 for a geothermal heat pump systemaccording to one embodiment. The polymer distribution pipe 10 comprises an elongatedcylindrical main pipe 11 having a continuous |atera| surface LS. The main pipe 11 has alength axis L1 extending in the center ofthe cylindrical main pipe 11. The main pipe 11 has a main cross-sectional area (shown as A1 in fig. 1C) being a perpendicular section to the length axis L1. The inner lumen of the cylindrical main pipe 11 has a circular cross-section, perpendicular to the center axis L1 of the main pipe 11, and a smooth continuous inner |atera| surface without holes.

[O30] The polymer distribution pipe 10 further comprises at least a first and a secondconnection pipe 13A; 13B having a closed base (14 of fig. 1C) formed by the continuous|atera| surface LS of the main pipe 11. ln the embodiment shown in fig. 1A, the polymerdistribution pipe 10 comprises a total of 20 connection pipes (shown as 13 in fig. 1B),each being connectable to one end of a geothermal collector. The end of the main pipe11 placed on lower portion of the drawing sheet comprising fig. 1A comprises a lid 15adapted to be welded (or attached by other mechanical or chemical means) to the endofthe main pipe 11, for sealing the end of the main pipe 11 not being connected to theheat pump system. Depending on the particular geothermal heat system in which thepolymer distribution pipe 10 should be used, the main pipe 11 may be cut to a lengthwhich includes a suitable number of connection pipes (13 of fig. 2). After the main pipe 11 has been cut, the lid 15 is welded to the end such that a closed system is created.

[031] The continuous |atera| surface LS of the main pipe 11 keeps the lumen of thepolymer distribution pipe 10 closed until it is drilled or milled for the purpose ofconnecting the polymer distribution pipe 10 to geothermal collectors (23 of fig. 1C).Keeping the lumen ofthe main pipe 11 closed enables the connection pipes to be drilledor milled and thus ”activated” only when they should be used, which makes it possible toleave a number of connection pipes un-drilled for the purpose of expanding the systemlater, by adding more collectors. The unused connection pipes (shown as 13C and 13D infig. 2) do not have to be sealed as they are already sealed at the base 14 by thecontinuous surface ofthe main pipe 11. A further advantage with having the polymerdistribution pipe 10 initially sealed, is that the risk that particles, fluids or material that may damage the system enters the polymer distribution pipe is reduced.

[O32] Turning again to the embodiment of the polymer distribution pipe 10 of fig. 1A, a first connection pipe 13A has a length axis L2 perpendicular to the length axis L1 of themain pipe 11 and a cross-sectional area (shown as A2 in fig. 1B) being circular andperpendicular to the length axis L2 of the first connection pipe 13A. The cross sectionalarea A2 is smaller than the main cross sectional area A1 ofthe main pipe 11, as the mainpipe 11 should allow a larger flow of heat transportation media than the connectionpipes. The second connection pipe 13B depicted in fig. 1A also has a length axis, L3,perpendicular to the length axis L1 of the main pipe 11, and a cross-sectional areaperpendicular to the length axis L3 ofthe second connection pipe 13B, being smaller than the main cross sectional area A1 of the main pipe 11.

[033] ln alternative embodiments it is conceivable that the connection pipes extendsfrom the main pipe 11 at an angle, such that a centrally placed length axis of the connection pipes is not perpendicular to the length axis of the main pipe 11.

[O34] According to the embodiment ofthe polymer distribution pipe shown in fig. 1A,the connection pipes (including the connection pipes 13A; 13B) are cylindrical, and eachof the first and second connection pipes has a substantially flat base 14. The flat base 14facilitates the step of drilling or milling a hole in the base 14 ofthe cylindrical connectionpipes, for establishing a fluid connection between the lumen of the main pipe and the connection pipes.

[035] According to one embodiment, the polymer distribution pipe 10 is manufacturedby means of injection molding in a single material, in which case the substantially flatbases 14 of the first and second connection pipes 13A, 13B are integrated in thecontinuous lateral surface ofthe main pipe 11. As the polymer distribution pipe 10 ismanufactured as a single piece of polymer material, no joints are created in the polymerdistribution pipe 10, and the risk that leaks occur in the polymer distribution pipe 10 issubstantially reduced. The polymer material may for example be Polyethylene (PE) withadded Carbon Black, and the amount of added Carbon Black may for example be between 0.5% and 3%. 11

[036] Fig. 1B shows the polymer distribution pipe in a plain side view. ln the view of fig.1B it is clearly shown that the connection pipes (e.g. 13A) have a circular cross-section A2being smaller than the circular cross-section A1 ofthe main pipe 11. ln the plain side view of fig. 1B the flat bases 14 of the cylindrical connection pipes 13 can also be seen.

[O37] Fig. 1C shows the polymer distribution pipe 10 in section A-A. ln the section of 1Cit is clearly shown that the cross-section of the lumen of the main pipe 11 is circular, andthat the connection pipe 13A has a flat base 14 formed by the continuous lateral surface of the main pipe 11.

[038] Fig. 2 shows a plain top view ofthe polymer distribution pipe 10 when installed ina manifold chamber 20. The main pipe 11 is in the embodiment shown in fig. 2joinedwith an in or outflow pipe 24 which in turn establishes a fluid connection with the heatpump of the geothermal heat pump system. The main pipe 11 and the in or outflow pipe24 are joined by means of welding at the wall of the manifold chamber 20, i.e. at thelocation where the connected main pipe 11 and in or outflow pipe 24 penetrates the wall of the manifold chamber 20.

[O39] ln the embodiment shown in fig. 2, the main pipe 11 has been cut, such thatpolymer distribution pipe 10 only comprises a total of 10 connection pipes. At the cutend of the polymer distribution pipe 10, the lid 15 has been welded to the main pipe 11,such that a closed system has been formed. 8 of the connection pipes are active andconnected to geothermal collectors 23 for extracting heat. Using the lower rightconnection pipe 13A as an example, the connection pipe 13A is connected to a first end22A of a valve 21. The second end of the valve 21 is connected to a geothermal collector23, such that a controllable fluid connection between the lumen ofthe main pipe 11 andthe collector 23 is established. As each of the geothermal heat collectors comprises avalve 21, the flow of fluid through the geothermal heat collectors can be turned off separately, which makes it much easier to locate leakage, and also enables a leak in a 12 single collector 23 to be repaired without shutting down the entire geothermal heat pUmp SyStem.

[040] Fig. 2 only shows one polymer distribution pipe 10, i.e. the figure only shows thepolymer distribution pipe 10 connected to one of the two pipes 24 connected to thegeothermal heat pump, i.e. the inflow or outflow pipe 24. A complete system thuscomprises a second complete polymer distribution pipe connecting the other end of thecollectors 23 to the a second inflow or outflow pipe 24, which in turn us connected tothe heat pump, such that a circulation of the heat transportation medium can be established.

[041] ln fig. 2, 2 unused connection pipes 13C, 13D are shown. The bottom (or base) ofthe unused connection pipes are sealed as the lateral surface of the main pipe 11,forming the base (14 of fig. 1C) of the cylindrical connection pipes, has not yet beendrilled. The unused connection pipes 13C, 13D may be used to expand the geothermal heat pump system by adding another two geothermal collectors 23 to the system.

[042] Fig. 3 is a flow chart describing a method of connecting a heat pump to a pluralityof geothermal collectors (23 in fig. 2) using the polymer distribution pipe (10 in e.g. fig1A) according to any one ofthe embodiments herein. The method comprises the steps ofcreating a through-hole in the lateral surface ofthe main pipe (11 in e.g. fig 1A), at thebase of the first or second connection pipe, within the lateral surface of the first orsecond connection pipe, such that a fluid connection between the lumen of the mainpipe 11 and the first or second connection pipe (13A and 13B in e.g. fig 1A) is created.The hole is for example created by means of drilling or milling and can be created in aworkshop prior to installation of the geothermal heat pump system, or at the location inwhich the geothermal heat pump system is installed. The method further comprises thesteps of mounting a first end (22A of fig. 2) of a valve (21 of fig. 2) on the connection pipewhich now has an established fluid connection with the lumen of the main pipe 11 and connecting the main pipe of the polymer distribution pipe to an in or outflow pipe (24 in 13 fig. 2) adapted to transport a heat transportation medium from the heat pump. Themethod further comprises the step of connecting a second end (22B of fig. 2) of the valve(21 in fig. 2) to a geothermal collector (23 of fig. 2), such that a controllable fluid connection between the collector and the heat pump is created.

[O43] The method of installing the polymer distribution pipe may according to oneembodiment be performed in a manifold chamber, such as the manifold chamber 20 shown in fig. 2.

[044] ln fig. 2, the polymer distribution pipe is described as being installed inside of amanifold chamber 20, however, it is equally conceivable that the polymer distributionpipe is installed in central within a building which also includes the heat pump and additional technical equipment required in the geothermal heat pump system.

[045] Please note that any of the polymer compositions or any combinations ofadditives mentioned herein could be used with any type of geothermal pipe collector without departing from the basic idea of the invention.

Claims

1. 4 CLAll\/IS 1. A polymer distribution pipe (10) for a geothermal heat pump system, the polymer distribution pipe (10) comprising: a main pipe (11) adapted to be connected to a geothermal heat pump, whereinthe main pipe has a continuous |atera| surface (LS) and a length axis (L1), and wherein a main cross-sectional area (A1) of the main pipe is perpendicular to the length axis (L1), at least a first and a second connection pipe (13A;13B), integrated in, andextending from, the continuous |atera| surface (LS) of the main pipe (11), wherein thecontinuous |atera| surface (LS) of the main pipe (11) forms a closed base (14) of the first and second connection pipes (13A;13B), and wherein the first connection pipe (13A) has a length axis (L2) extending ina center ofthe first connection pipe (13A) and a cross-sectional area (A2)perpendicular to the length axis (L2), being smaller than the main cross sectional area (A1) of the main pipe (11), and the second connection pipe (13B) has a length axis (L3) extendingin a center of the second connection pipe (13B) and a cross-sectional areaperpendicular to the length axis (L3) of the second connection pipe (13B), being smaller than the main cross sectional area (A1) of the main pipe (11).

2. The polymer distribution pipe according to claim 1, wherein the closed base (14) ofthe first and second connection pipes (13A;13B) are integrated in the continuous |atera| surface (LS) of the main pipe (11).

3. The polymer distribution pipe according to any one of claims 1 and 2, wherein the first and second connection pipes (13A;13B) are cylindrical. P 10. 11. The polymer distribution pipe according to any one ofthe preceding claims, whereinthe closed bases (14) ofthe first and second connection pipes (13A;13B) are su bsta ntially flat. The polymer distribution pipe according to any one ofthe preceding claims, wherein the main cross-sectional area (A1) is circular. The polymer distribution pipe according to any one of the preceding claims, whereinthe cross-sectional areas (A2) of the first and second connection pipes (13A;13B) are circular. The polymer distribution pipe according to any one of the preceding claims, wherein the polymer distribution pipe (10) comprises polyethylene. The polymer distribution pipe according to any one of the preceding claims, wherein the polymer distribution pipe (10) comprises carbon black. The polymer distribution pipe according to claim 8, wherein the polymer distribution pipe (10) comprises between 0.5% and 3% carbon black. The polymer distribution pipe according to any one of the preceding claims, further comprising a lid (15) adapted to close one end of the main pipe (11). A method of connecting a heat pump to a plurality of geothermal collectors using thepolymer distribution pipe according to any one of claims 1 - 10, the method comprising: creating (A) a through-hole in the continuous lateral surface (LS) of the main pipe (11), within the lateral surface of the first or second connection pipe (13A;13B), such that a fluid connection between the lumen of the main pipe (11) and the first or second connection pipe (13A;13B) is created, 16 mounting (B) a first end (22A) of a valve (21) on the connection pipe (13A) having a fluid connection with the main pipe (11), connecting (C) the main pipe (11) of the polymer distribution pipe (10) to an inor outflow pipe (24) adapted to transport a heat transportation medium from the heat pump, and connecting (D) a second end (22B) of the valve (21) to a geothermal co||ector(23), such that a controllable fluid connection between the co||ector (23) and the heat pump is created. 12. The method of installing the polymer distribution pipe according to any one of c|aims1 - 10, wherein the step of connecting (D) the second end of the valve (22B) to a geothermal co||ector (23) is performed in a manifo|d chamber (20). 13. A manifo|d chamber (20) for a geothermal heat pump system comprising the polymer distribution pipe (10) according to any one of c|aims 1 - 10. 14. Use of the polymer distribution pipe (10) according to any one of c|aims 1 - 10, in a geothermal heat pump system.