CN119509236A - A plum blossom-shaped underground pipe heat exchanger and construction method - Google Patents

Abstract

The invention discloses a plum blossom-shaped buried pipe heat exchanger and a construction method, comprising an inner pipe, an outer pipe and a bottom closed section, wherein a plurality of outer pipes are arranged on the outer wall of the inner pipe at intervals, and adjacent outer pipes are not in contact with each other, thereby effectively increasing the contact area between the outer pipe and the formation, and significantly improving the heat exchange amount and heat exchange efficiency of the outer pipe; the outer wall surface of the inner pipe is tangent to the contour line of the outer wall surface of the outer pipe, and point contact is established between the outer pipe and the inner pipe, so that the contact area is significantly reduced, thereby reducing the heat loss caused by the heat exchange from the high-temperature fluid in the inner pipe to the outer pipe; during the construction process, by filling the backfill material with low thermal conductivity coefficient outside the inner pipe and between adjacent outer pipes, the heat loss of the hot fluid in the inner pipe to the outside is further reduced, and the heat extraction efficiency of the buried pipe single well is greatly improved, thereby saving the construction cost of utilizing medium and deep geothermal energy.

Description

Quincuncial buried pipe heat exchanger and construction method

Technical Field

The invention belongs to the technical field of buried pipe heat exchanger structures, and particularly relates to a quincuncial buried pipe heat exchanger and a construction method thereof.

Background

The underground heat exchanger, also called an underground heat exchanger or a ground source heat pump, is equipment for air conditioning and heating by utilizing underground heat energy, and realizes heat exchange with fluid in a pipe by burying a pipeline underground and utilizing the stable temperature of underground soil or a water source;

The sleeve type buried pipe heat exchanger is one kind of buried pipe heat exchanger, and is formed by connecting coaxial sleeves with different diameters according to U-shaped elbows, wherein the coaxial sleeves are used for realizing heat exchange between underground fluid and fluid in the pipe by utilizing a sleeve structure;

In order to reduce the number of wells to save initial investment, the double pipe type buried pipe heat exchanger is a type of heat exchanger commonly used for geothermal extraction, limited by its limited heat exchange area, and research on heat exchange efficiency improvement based on such a type of heat exchanger has gradually been in the bottleneck.

Disclosure of Invention

The invention aims to provide a quincuncial buried pipe heat exchanger and a construction method thereof, which aim to solve the technical problem of low heat exchange efficiency of the existing sleeve type buried pipe heat exchanger.

In order to solve the problems, the invention adopts the following technical scheme:

The quincuncial buried pipe heat exchanger comprises an inner pipe, wherein a plurality of outer pipes are arranged outside the inner pipe at intervals, and the same ends of the inner pipe and the plurality of outer pipes are connected with bottom sealing sections;

The inner pipe and the outer pipe are in point contact;

The inner tube has a lower thermal conductivity than the outer tube.

Furthermore, the inner tube and the outer tube are cylindrical tubes.

Further, the pipe diameter of the inner pipe is larger than that of the outer pipe.

Furthermore, the inner tube adopts a PE tube.

Furthermore, the outer tube adopts stainless steel tube.

Further, the bottom closing section is a hollow cylindrical structure.

Further, a through hole is formed in the end face of one side, connected with the inner pipe and the outer pipe, of the bottom sealing section.

Further, a plurality of outer tubes outside the inner tube are uniformly arranged at intervals.

Furthermore, the inner tube and the plurality of outer tubes all adopt smooth inner wall structures.

In a second aspect, a construction method of a quincuncial buried pipe heat exchanger is provided, which comprises the following steps:

Bonding a plurality of outer tubes on the outer wall of the inner tube at intervals;

connecting the ends of the inner tube and the outer tube with the bottom closed section;

the assembled borehole heat exchanger is inserted into an underground borehole and backfill material is injected into the borehole.

Compared with the prior art, the invention has the following beneficial technical effects:

The invention provides a quincuncial buried pipe heat exchanger, which comprises an inner pipe with one end fixed on a bottom closed section and a plurality of outer pipes arranged on the outer wall of the inner pipe at intervals, wherein the heat conductivity coefficient of the inner pipe is lower than that of the outer pipe, the heat exchange area between the outer pipe and surrounding soil is effectively increased under the condition of keeping the size close to that of the underground space occupied by a common double-pipe buried pipe heat exchanger, the heat exchange amount and the heat exchange efficiency of the outer pipe are obviously improved, the outer wall surface of the inner pipe is tangent to the outline of the outer wall surface of the outer pipe, the contact area is obviously reduced through the contact between the outer pipe and the inner pipe, and therefore the heat loss caused by heat exchange of high-temperature fluid of the inner pipe to the outer pipe is reduced.

Preferably, the pipe diameter of the inner pipe is designed to be larger than that of the outer pipe, so that a plurality of outer pipes and one inner pipe form a heat exchange system.

Preferably, a plurality of outer tubes outside the inner tube are uniformly arranged on the outer wall of the inner tube at intervals, the outer tubes are distributed along the circumferential direction of the inner tube and are uniformly laid, the whole heat exchanger is tightly arranged, and the required drilling aperture is reduced to the greatest extent.

The invention provides a construction method of a quincuncial buried pipe heat exchanger, in the construction process, firstly, underground drilling is carried out by utilizing a drilling machine, then, the assembled novel buried pipe heat exchanger is put into the ground, finally, backfilling materials are injected into the drilling holes for well cementation, the backfilling materials with low heat conductivity coefficient are filled between the outer part of an inner pipe and an adjacent outer pipe, so that outer pipe fluid and the outer wall surface of the inner pipe are separated by the outer pipe wall surface and the backfilling materials of the drilling holes, the inner pipe fluid and the outer pipe fluid are further separated, the heat loss of the inner pipe thermal fluid outwards is further reduced, the heat exchange capacity and the heat exchange efficiency of the buried pipe heat exchanger are obviously improved, and the single well heat extraction efficiency of the buried pipe is greatly improved, thereby saving the construction cost for utilizing middle-deep geothermal energy and promoting the wide application of geothermal energy heating technology in the construction field.

Drawings

FIG. 1 is a diagram of a quincuncial buried pipe heat exchanger according to an embodiment of the present invention;

FIG. 2 is a diagram of the top end structure of a quincuncial buried pipe heat exchanger in an embodiment of the present invention;

FIG. 3 is a diagram of the bottom end structure of a quincuncial buried pipe heat exchanger in an embodiment of the present invention;

Fig. 4 is a flow chart of a construction method of a quincuncial buried pipe heat exchanger in an embodiment of the invention.

Detailed Description

In order to make the technical problems, technical schemes and beneficial effects solved by the invention more clear, the following specific embodiments are used for further describing the invention in detail. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that like reference numerals and letters refer to like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.

In the description of the embodiments of the present invention, it should also be noted that, unless explicitly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected through an intermediate medium, or communicating between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

The quincuncial buried pipe heat exchanger comprises an inner pipe, an outer pipe and a bottom sealing section, wherein a plurality of outer pipes are arranged on the outer wall of the inner pipe at intervals, and adjacent outer pipes are not contacted, so that the contact area between the outer pipe and a stratum is effectively increased, the heat exchange between the outer pipe and the outside is better, and the heat exchange effect is improved;

In order to improve the heat exchange efficiency, the quincuncial buried pipe heat exchanger is characterized in that the inner pipe and the outer pipe are made of materials, the heat conductivity coefficient of the inner pipe is lower than that of the outer pipe, namely the inner pipe is made of materials with low heat conductivity efficiency, so that the heat loss of the inner pipe hot fluid outwards is avoided;

As shown in fig. 2, the outer pipe and the inner pipe of the structure are in point contact, the outer wall surface of the inner pipe is tangent to the outline of the outer wall surface of the outer pipe, so that the contact area between the inner pipe and the outer pipe is obviously reduced, and the heat loss caused by heat exchange of high-temperature fluid in the inner pipe to the outer pipe is reduced.

In an optional implementation mode, the inner pipe is a PE pipe, the outer pipes are stainless steel pipes, the end parts of the outer pipes are all water inlets, and the end parts of the inner pipes are water outlets, so that the pipe diameter of the inner pipe is designed to be larger than that of the outer pipes;

The outer tubes and the inner tubes are adhered by an adhesive, and the outer tubes are uniformly arranged at intervals.

In the embodiment, a quincuncial buried pipe heat exchanger is provided, which comprises 1 cylindrical inner pipe made of low heat conduction material, a plurality of outer pipes made of high heat conduction material and a cylindrical sealing section at the bottom, wherein the inner pipe and the outer pipe are connected. The inner pipe and the outer pipe are tightly laid;

the inner tube is made of materials with low heat conductivity coefficients, and mainly comprises various PE tubes, so that heat loss of the inner tube heat fluid outwards is effectively avoided. The outer tube is made of a material with high heat conductivity coefficient and is used for fully exchanging heat with surrounding soil, and the stainless steel tube is mainly used. The outer tube is distributed along the circumference of the inner tube, and is laid uniformly, and the inner tube and the outer tube integrally form a quincuncial heat exchanger. And moreover, the outer wall surface of the inner tube is tangent to the outline of the outer wall surface of the outer tube, the whole heat exchanger is closely arranged, and the required drilling aperture is reduced to the greatest possible extent.

Alternatively, as shown in fig. 3, the bottom closing section is a cylindrical hollow structure, and the inner and outer tubes are connected to the bottom closing section in an inserted manner.

In the embodiment, the quincuncial buried pipe heat exchanger comprises an inner pipe and a plurality of outer pipes in point contact with the inner pipe system, wherein the adjacent outer pipes are not in contact, the contact area of the outer pipes and a stratum is effectively increased, and the inner pipe and the outer pipe are tightly laid.

The same ends of the inner pipe and the plurality of outer pipes are connected with the bottom closed section in an inserted mode, the bottom closed section is of a cylindrical hollow structure, low-temperature water flows in from the top through the outer pipe in the operation process, absorbs heat from external high-temperature soil in the falling process, flows out of the middle inner pipe under the action of pressure after entering the bottom closed section, and enters heat equipment through an overground system pipeline connected with the structure of the invention, so that heat supply of a building is realized.

The pipe diameter of the inner pipe can be 10cm to 30cm, the wall thickness is about 5mm, and the pipe diameter of the outer pipe is 6.2cm to 18.6cm, so that the outer pipes are ensured not to be contacted with each other. The length can be adjusted according to the actual requirements (typically 50m to 3000 m). One end of the pipeline is a bottom closing section, and the other end of the pipeline is a top outlet and is connected with a pipeline in an above-ground building system. The inner pipe and the outer pipe are adhered by an adhesive, and the outer pipes are not contacted with each other;

in a further embodiment of the invention, the inner walls of the inner and outer tubes are smooth wall surfaces.

According to the quincuncial buried pipe heat exchanger, on one hand, under the condition that the cross section area of the outer pipe of the quincuncial buried pipe heat exchanger is kept the same as that of an outer pipe of a common casing pipe type buried pipe heat exchanger, the heat exchange area between the outer pipe and surrounding soil is effectively increased, so that the heat exchange quantity and the heat exchange efficiency of the outer pipe are obviously improved;

In addition, the outer tube fluid in the traditional sleeve type buried tube heat exchanger is directly contacted with the outer wall surface of the inner tube, namely, the heat transfer process between the inner tube fluid and the outer wall surface of the inner tube is that the heat transfer process between the outer wall surface of the inner tube and the heat transfer process between the outer tube fluid and the outer wall surface of the inner tube is that the heat transfer process between the outer tube fluid and the heat transfer process. The novel quincuncial buried pipe heat exchanger provided by the invention enables the outer pipe fluid and the outer wall surface of the inner pipe to be separated by the outer pipe wall surface and the drilling backfill material, and the inner pipe fluid and the outer pipe fluid are further separated. The heat transfer process of the inner and outer tube fluids at this time is changed into the heat convection between the inner tube fluids and the outer wall surface of the inner tube, the heat conduction through the tube wall of the inner tube, the heat conduction through the backfill layer, the heat conduction through the tube wall of the outer tube and the heat convection between the outer tube fluids and the inner wall surface of the outer tube. The heat resistance is obviously improved, and the heat loss of the inner tube hot fluid outwards is further reduced. The heat exchange quantity and the heat exchange efficiency of the buried pipe heat exchanger are obviously improved.

Working principle:

In the form of the quincuncial buried pipe heat exchanger, low-temperature water flows in through the water inlet of the outer pipe, firstly enters the inner part of the outer pipe and performs full heat exchange with surrounding soil. During this process, the water temperature flowing into the outer tube gradually increases. After heat exchange with the soil, water flow in the outer pipe continuously flows downwards, enters a closed section at the bottom of the buried pipe heat exchanger and is converged into the inner pipe. The fluid in the inner tube flows from bottom to top, and the heat loss from the outside is avoided to the greatest extent due to the material of the heat conductivity coefficient of the inner tube, and finally flows out of the heat exchanger system from the outlet of the inner tube, so that the heat exchange process is completed.

The invention also provides a construction method of the quincuncial buried pipe heat exchanger, as shown in fig. 4, comprising the following steps:

Bonding a plurality of outer tubes on the outer wall of the inner tube at intervals;

connecting the ends of the inner tube and the outer tube with the bottom closed section;

the assembled borehole heat exchanger is inserted into an underground borehole and backfill material is injected into the borehole.

In the construction process, firstly, underground drilling is carried out by utilizing a drilling machine, then the assembled novel buried pipe heat exchanger is placed underground, and finally, backfilling materials are injected into the drilling holes for well cementation.

The novel quincuncial heat exchanger can improve the heat exchange capacity of the buried pipe under the unit occupied area and the cost on the premise of not increasing the drilling cost and the occupied area on the ground.

The buried pipe heat exchanger enables the outer pipe fluid and the outer wall surface of the inner pipe to be separated by the outer pipe wall surface and the drilling backfill material, and the drilling backfill material adopts the material with the ground heat conductivity coefficient, so that the inner pipe fluid and the outer pipe fluid are further blocked, and the heat loss of the inner pipe thermal fluid outwards is reduced.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims (10)

1. The quincuncial buried pipe heat exchanger is characterized by comprising an inner pipe, wherein a plurality of outer pipes are arranged outside the inner pipe at intervals, and the same ends of the inner pipe and the plurality of outer pipes are connected with a bottom sealing section;

The inner pipe and the outer pipe are in point contact;

The inner tube has a lower thermal conductivity than the outer tube.

2. A quincuncial buried pipe heat exchanger according to claim 1, wherein the inner and outer pipes are cylindrical pipes.

3. A quincuncial buried pipe heat exchanger according to claim 2, wherein the inner pipe diameter is larger than the outer pipe diameter.

4. A quincuncial buried pipe heat exchanger according to claim 1 or 2, wherein the inner pipe is a PE pipe.

5. A quincuncial buried pipe heat exchanger according to claim 1 or 2, wherein the outer pipe is stainless steel.

6. A quincuncial buried pipe heat exchanger according to claim 1, wherein the bottom closing section is of hollow cylindrical structure.

7. The quincuncial buried pipe heat exchanger of claim 6, wherein the bottom closing section is provided with a through hole on one side end surface connected with the inner pipe and the outer pipe.

8. A quincuncial buried pipe heat exchanger according to claim 1, wherein a plurality of outer pipes are uniformly spaced apart from the inner pipe.

9. The quincuncial buried pipe heat exchanger of claim 8, wherein the inner pipe and the plurality of outer pipes each have a smooth inner wall structure.

10. A construction method of a quincuncial buried pipe heat exchanger, characterized in that the quincuncial buried pipe heat exchanger according to any one of claims 1-9 comprises the following steps:

Bonding a plurality of outer tubes on the outer wall of the inner tube at intervals;

connecting the ends of the inner tube and the outer tube with the bottom closed section;

the assembled borehole heat exchanger is inserted into an underground borehole and backfill material is injected into the borehole.