KR101262315B1 - Construction method of underground heat exchanger using alluvial auifer apllying the same - Google Patents

Abstract

PURPOSE: A construction method for a soil heat exchanger using an alluvial aquifer is provided to acquire heat from underwater and to efficiently return the underwater used for heat acquisition through a drain pipe into the earth. CONSTITUTION: A construction method for a soil heat exchanger using an alluvial aquifer is composed of the following steps: An upright radial drain unit having a greater pipe diameter than the diameter of a second casing is inserted into a first casing, and a gap between the first casing and the upright radial drain unit is filled with pebbles. The first casing is removed. The upright radial drain unit comprises a body(10) and a drainpipe(20). The body has a pillar shape with an open upper side and a hollowed inside. The drainpipe discharges subsurface water which flows inside the body to the outside. The upright radial discharge unit is inserted between the first casing and the second casing and reaches the upper side of a grouting.

Description

Construction method of underground heat exchanger using alluvial aquifer {CONSTRUCTION METHOD OF UNDERGROUND HEAT EXCHANGER USING ALLUVIAL AUIFER APLLYING THE SAME}

The present invention relates to a construction method of an underground heat exchanger using an alluvial aquifer, and more particularly, in a system for cooling and heating a building using an underground heat exchanger installed in an alluvial bed in which an aquifer flows, the heat is obtained from groundwater and used. The present invention relates to a method of constructing an underground heat exchanger using a granular radial drainage field for an underground heat exchanger used to send groundwater back to the ground.

In general, geothermal heat is distributed below the earth's surface and is the heat retained by soil and rock due to solar radiation or magma heat inside the earth.

The alluvial aquifer is a layer containing groundwater and consists of sand, gravel, silt, clay, etc., and groundwater exists while saturating the air gaps in the rocks constituting these layers.

The geothermal heat of the alluvial aquifer is maintained at a constant temperature throughout the year, and the groundwater with abundant groundwater is used for cooling and heating by using a constant water temperature (about 15 ° C) throughout the year.

The heating and cooling system using the alluvial aquifer is known to be an efficient and eco-friendly method, and it has been developed as a heat pump system of various methods because it is the most economical and effective among the methods for reducing carbon dioxide emission causing global warming.

As a related art, "Underground heat exchanger" of Korean Patent No. 1055374, which has been filed and registered by the present applicant, is disclosed.

The underground heat exchanger according to Korean Patent No. 1055374 is composed of an underground heat exchanger that isolates groundwater in an alluvial aquifer, that is, pumps groundwater present in a lower layer, and injects groundwater into an upper layer of an alluvial aquifer. The casing of the outer casing, characterized in that the inner wall is provided in the center so that the upper injection portion for injecting ground water and the lower pumping portion for pumping ground water is separated.

In this case, when the building is cooled and heated by operating a heat pump (heat pump) using the groundwater included in the alluvial aquifer as a heat source, the groundwater is pumped and the heat exchange is performed through a heat exchanger. In the process of returning groundwater back to the ground, it is necessary to facilitate the process of ground discharge.

Conventionally, in order to allow the groundwater used for the single-hole type (open type, SCW type) geothermal system to be converted to a temperature similar to the ground temperature and reused, a depth of 500 m or more is drilled and a double pipe type groundwater movement passage is provided. By forming, a method of converting groundwater to a usable temperature and reusing it is used.

However, in the method of using groundwater included in the alluvial aquifer, the required temperature is obtained by pumping the required groundwater at the lower part of the impervious layer by using the impervious layer, which is a geological characteristic of the alluvial layer, and using the groundwater. The purpose is to continuously use the groundwater with a constant and stable temperature by preventing the groundwater used to mix by discharging to the top of the impermeable layer again.

The groundwater used in this alluvial method is discharged to the upper part of the impermeable layer and slowly permeates back to the lower part of the impermeable layer by its own gravity or flows along the underground channel through the naturally formed aquifer. .

However, depending on the capacity of the air-conditioning system, the amount of groundwater used is large, or the drainage is not smoothly performed or flows back to the ground depending on the soil composition and condition of the top of the impervious layer where natural discharge proceeds. There is a problem that can occur.

In order to prevent such a backflow phenomenon that may occur during drainage, the application of a pressurization device in the drainage pipe for drainage promotion or the operation of a drainage system for smoothly performing natural drainage is essential for the underground heat exchange system using an alluvial aquifer. Part.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of constructing an underground heat exchanger to effectively drain the groundwater used in the underground heat exchanger system installed in the alluvial aquifer.

An object of the present invention described above is to form a first insertion hole by drilling the ground to the alluvial layer, inserting the first casing for earth retaining into the first insertion hole, and the ground under the first casing Forming a second insertion hole by drilling a diameter smaller than the first insertion hole, inserting a second casing having a diameter smaller than the diameter of the second insertion hole in the center of the second insertion hole; Cement grouting between the outer surface of the second casing and the inner surface of the second insertion hole to fix the second casing, and drilling the ground of the lower portion of the second casing with a diameter smaller than the diameter of the second insertion hole. Forming a third insertion hole, inserting a third casing smaller than the diameter of the third insertion hole into the third insertion hole, and inserting an underwater pump into the third casing to form a supply passage for groundwater. Outside Forming a lower strainer, inserting a radial radial drainage device having a larger diameter than the second casing in the first casing and filling gravel in the space between the first casing and the drainage device; Removing the casing.

Here, the granular radial drainage is preferably inserted to the grouting upper surface between the first casing and the second casing.

And forming a drainage space by discharging the drainage around the first insertion hole, and forming a drainage path connected to the drainage space to discharge the discharged water into the ground.

In addition, the coarse gravel in the drainage space, the bottom of the gravel is filled with gravel to form a gravel layer, and further comprising the step of filling the soil from the top surface of the gravel layer to the earth.

According to the present invention, heat can be obtained from the groundwater and the used groundwater can be efficiently sent back to the ground through the radially formed drain pipe.

1 is a perspective view showing a granular radial drainage device for an underground heat exchanger according to an embodiment of the present invention.
FIG. 2 is a front view of the granular radial drainage system for the underground heat exchanger shown in FIG. 1. FIG.
3 is a cross-sectional view showing the construction process of the underground heat exchanger using the alluvial aquifer to which the granular radial drainage device for the underground heat exchanger shown in FIG. 1 is applied.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood, however, that the embodiments described below are only for explanation of the embodiments of the present invention so that those skilled in the art can easily carry out the invention, It does not mean anything. In describing various embodiments of the present invention, the same reference numerals will be used to refer to elements having the same technical features.

The present invention relates to a method of using a plurality of granular drainage systems having a polygonal radial height difference in the process of draining groundwater used as an energy source for cooling and heating back to the ground.

1 and 2, the granular radial drainage device for an underground heat exchanger according to an embodiment of the present invention includes a body 10 and a plurality of drainage pipes 20.

The body 10 has a columnar shape with a lower surface open and an empty inside. The body 10 may have a columnar shape, for example, a cylinder or a polygonal column. In FIG. 1 and FIG. 2, the body 10 has one example of a hexagonal column. Groundwater is introduced into the lower surface of the body (10).

The drain pipe 20 is provided to discharge the groundwater introduced into the body 10 to the outside, is formed to protrude in the horizontal direction on the outer surface of the body 10, preferably of the body 10 to form a radial Protruding from each outer surface. The drain pipe 20 may be integrally formed with the body 10 or may be configured to be detachably assembled to the body 10.

Drainage device according to an embodiment of the present invention is buried in the ground with the drain pipe 20 is formed in the body 10, hereinafter will be described with respect to the construction method and operation relationship of the underground heat exchanger using the alluvial aquifer. .

The sedimentary layer consisting of alluvial layers due to sedimentation is characterized by the repeated occurrence of sedimentary layers consisting of gravel, sand, clay, etc. Under the determined impervious layer, the groundwater to be used as a heat source of the geothermal system is pumped down, and the groundwater used between the impervious layer and the ground surface is drained again so that the upper and lower groundwater is not mixed.

Heat pumps that perform cooling and heating using geothermal heat as a heat source generally undergo a preheating process in order to reach an appropriate temperature at initial operation in a stationary state, and perform heating and cooling instead of continuously operating for a long time when the proper temperature is maintained. Repeat the operation and stop until the proper temperature.

That is, during the initial operation time, the groundwater circulation proceeds by continuous heat pump operation, which is the time when the amount of groundwater to be drained occurs the most. In fact, in one heat exchanger of an alluvial water system, generally 30usRT (90,720Kcal / h, 105.5kW) in consideration of the capacity of about 18,144㎥ of groundwater to operate for about an hour without rest is the capacity to drain back to the ground.

Referring to Figure 3 the construction process as follows.

First, the ground is drilled to the alluvial aquifer to form the first insertion hole H1. In this case, the first insertion hole H1 is formed to an alluvial layer having a diameter of about 500 mm or more and having a depth of about 6 to 10 m in which sand and gravel exist.

Thereafter, the first casing for earth barrier is inserted into the first insertion hole H1. In this case, since the first casing 1 is used for the retaining film, the outer diameter is formed to be approximately equal to the diameter of the first insertion hole H1.

Thereafter, the ground of the lower portion of the first casing 1 is drilled into a smaller diameter than the first insertion hole H1 to form a second insertion hole H2. In this case, the second insertion hole H2 is formed in the ground of the lower part of the 1st casing 1 to the part of rock about 15m in diameter about 250 mm.

Thereafter, the second casing 2 having a diameter smaller than the diameter of the second insertion hole H2 is inserted into the center portion of the second insertion hole H2. In this case, the diameter of the second casing 2 may be about 200 mm. The second casing 2 serves as a separation layer separating the feed water and the return water.

Thereafter, cement grouting is performed between the outer surface of the second casing 2 and the inner surface of the second insertion hole H2. The second casing 2 is fixed and grouted to form an isolation structure so that the used and discharged return water does not mix with the feed water.

Thereafter, the ground of the lower portion of the second casing 2 is drilled into a diameter smaller than the diameter of the second insertion hole H2 to form a third insertion hole H3. In this case, the third insertion hole H3 is formed in order to secure and maintain the groundwater of the aquifer layer, and is formed up to about 50m with a diameter of 200 mm.

Subsequently, a third casing 3 smaller than the diameter of the third insertion hole H3 is inserted into the third insertion hole H3, and an underwater pump is inserted into the third casing 3 to supply the groundwater supply passage. And strainer under the outer surface. The third casing 3 has a diameter approximately equal to the diameter of the third insertion hole, and the strainer may be installed to filter gravel and sand at a height of about 35 m from the bottom of the third casing 3.

Subsequently, a granular radial drainage device having a larger diameter than the second casing 2 is inserted into the first casing 1 and the gravel is filled in the space between the first casing 1 and the drainage device.

In this case, the granular radial drainage device is located up to the grouting top surface, and its diameter is suitably about 350 mm.

Since the gravel 100 is filled in the space between the outer surface of the body 10 of the drainage system and the first casing 1, the drainage pipe 20 of the drainage device is also buried underground by the gravel, and the second casing 2. Used ground water flowing through the space between the and the third casing (3) is introduced into the body (10) of the drainage device and then discharged into the ground through the drain pipe (20).

The gravel 100 is suitably about 13 mm.

Thereafter, the first casing 1 is removed. Since the first casing 1 was originally inserted for use as a retainer, it is preferable to remove it.

On the other hand, the drain hole is formed around the first insertion hole (H1) to form a drainage space, it may be connected to the drainage space to form a drainage path to discharge the drainage to the ground.

In addition, after the coarse gravel is filled in the drainage space and the gravel is positioned above the gravel layer to form the gravel layer 200, the method may further include filling the soil with soil from the top surface of the gravel layer.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention, It is obvious that the claims fall within the scope of the claims.

1: first casing
2: second casing
3: third casing
10: Body
20: drain pipe

Claims (4)

Drilling the ground to the alluvial aquifer to form a first insertion hole;
Inserting a first casing for earth blocking into the first insertion hole;
Forming a second insertion hole by drilling the ground of the lower portion of the first casing with a smaller diameter than the first insertion hole;
Inserting a second casing having a diameter smaller than the diameter of the second insertion hole at the center of the second insertion hole;
Cement grouting between an outer surface of the second casing and an inner surface of the second insertion hole to fix the second casing;
Forming a third insertion hole by drilling the ground of the lower portion of the second casing with a diameter smaller than that of the second insertion hole;
Inserting a third casing smaller than the diameter of the third inserting hole into the third inserting hole, inserting an underwater pump into the third casing to form a supply passage for groundwater, and forming a strainer under the outer surface;
Inserting a granular radial drainage device having a larger diameter than the second casing into the first casing and filling gravel in the space between the first casing and the drainage device; And
Removing the first casing; Construction method of an underground heat exchanger using an alluvial layer comprising a. The method of claim 1,
The granular radial drainage device
A pillar-shaped body having an open lower surface and an empty interior,
It includes a drain pipe for discharging the groundwater introduced into the body to the outside,
The construction method of the underground heat exchanger using an alluvial layer, characterized in that inserted into the upper surface of the grouting between the first casing and the second casing. The method of claim 1,
Underground heat exchange using the alluvial layer further comprising the step of forming a drainage space by discharging the drain circumference around the first insertion hole, and connected to the drainage space to form a drainage path to discharge the discharged water into the ground. Construction method of the flag. The method of claim 3, wherein
The gravel is filled with gravel so that the coarse gravel is located at the bottom of the drainage space, and the gravel layer is located above, and the soil is filled with soil from the top surface of the gravel layer to the ground. Construction method of heat exchanger.

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