WO2015141878A1

WO2015141878A1 - Ground heat exchanger to which pcm fusion grout is applied and method for installing same

Info

Publication number: WO2015141878A1
Application number: PCT/KR2014/002384
Authority: WO
Inventors: 김수민; 정수광; 유슬기
Original assignee: 숭실대학교산학협력단
Priority date: 2014-03-21
Filing date: 2014-03-21
Publication date: 2015-09-24
Also published as: KR101541781B1; WO2015141878A9

Abstract

A ground heat exchanger, to which PCM fusion grout is applied, comprises: a pile, which has a hollow portion formed at the center thereof, and which is installed in the ground; a heat exchange pipe, which contains a heat exchange medium, and which is arranged in the hollow portion of the pile; and grout which fills the space between the heat exchange pipe and the inner surface of the hollow portion, thereby performing heat exchange with the heat exchange medium, wherein the grout comprises a first grout member comprising shape stabilized phase change materials (SSPCM). Accordingly, a highly-efficient ground heat exchanger can be provided.

Description

[Correction 31.03.2014] according to Rule 26. Geothermal heat exchanger applying PCM fusion grout and construction method thereof

The present invention relates to a ground heat exchanger using a PCM fusion grout and a construction method thereof, and more particularly, to a ground heat exchanger using a PCM fusion grout for application to a ground heat pump system and a construction method thereof.

Recently, in order to cope with high oil prices, the construction industry is actively developing alternative energy that can replace oil or natural gas as an energy source used for heating and cooling. Among these alternative energy sources, technologies that can be applied to air-conditioning systems using wind, solar, geothermal, etc., which have infinite energy sources, are being studied. These energy sources have little effect on air pollution and climate change. While there is an advantage to obtain a low energy density has the disadvantage.

In order to obtain wind and solar energy, a large area must be secured along with the limit of the installation site. These devices have a limited energy production and cost to install and maintain.

Since geothermal energy is relatively inexpensive to install and maintain, many heating and cooling systems using geothermal heat as a heat source have been proposed.

Geothermal energy can be categorized into direct use and indirect use technologies according to the depth and temperature used. Geothermal heat pump system (geothermal heat pump system) is the largest part of the direct use technology of geothermal energy. heat pump system). The geothermal heat pump system, which is receiving much attention as a building renewable energy facility, is a combined cooling and heating system composed of a ground heat exchanger and a geothermal heat pump unit.

In addition, it is regarded as a highly efficient system because it utilizes the constant temperature of the underground which is hardly affected by outside air. Korea mainly uses vertical geothermal heat pump system, the core of which can be seen as heat pump and underground heat exchanger. The geothermal heat exchanger is completed by inserting a U-shaped polyethylene pipe into the borehole and then filling the void space between the pipe and the borehole with grouting material. At this time, grouting to fill an empty space with a material having a proper thermal conductivity and a small hydraulic conductivity (permeability) is the most important factor for the performance of the ground heat exchanger.

However, conventionally used grouting materials such as concrete or bentonite have a problem in that the heat transfer efficiency of receiving heat from the ground is low. That is, bentonite has a thermal conductivity of 0.8 to 0.9, and concrete has a thermal conductivity of 0.43 to 1.25 when dried and 0.83 to 2.12 when wet, which leads to limitations in using geothermal efficiency due to poor heat transfer efficiency.

Accordingly, the technical problem of the present invention was conceived in this respect, and an object of the present invention is to provide a geothermal heat exchanger using a PCM fusion grout capable of maximizing temperature and heat.

Another object of the present invention is to provide a construction method of the above ground heat exchanger.

An underground heat exchanger to which the PCM fusion grout is applied according to an embodiment for realizing the object of the present invention includes: a hollow having a center and installed in the ground; A heat exchange pipe containing a heat exchange medium and disposed in the hollow of the pile; And a grout filled between the heat exchange pipe and the hollow inner surface to perform heat exchange with the heat exchange medium, wherein the grout includes a first grout material comprising a shape stabilized phase change material (SSPCM). Include.

In an embodiment of the present invention, the grout further includes a second grout material, the second grout material may include at least one of bentonite, cement, concrete, earth and sand, sand and soy gravel.

In an embodiment of the present invention, the grout may be alternately laminated with the first grout material and the second grout material.

In an embodiment of the present invention, the grout may be formed by mixing the first grout material and the second grout material.

In an embodiment of the present invention, the heat exchange pipe is formed in a double cylindrical structure, the heat exchange medium is contained therein, the core portion formed in the longitudinal center; And a cladding part surrounding the core part and containing a phase stable phase change material.

In an embodiment of the present invention, the cladding portion may include at least one partition wall for fixing the phase stable phase change material in a longitudinal direction.

In an embodiment of the present invention, the phase stable phase change material is at least one of a phase change material formed by mixing a phase change material in a polymer, a phase change material formed by impregnating a phase change material and an encapsulated phase change material in a porous material. It may include.

According to another aspect of the present invention, there is provided a construction method of a ground heat exchanger including a first grout material including a shape stabilized phase change material (SSPCM) in the hollow. Pouring the grout; And installing a heat exchange pipe containing a heat exchange medium in the hollow in which the grout is poured.

In an embodiment of the present invention, in the pouring of the grout, the first grout material and the second grout material may be alternately stacked.

In an embodiment of the present invention, the step of pouring the grout, it is possible to pour the grout formed by mixing the first grout material and the second grout material.

In an embodiment of the present invention, the second grout material may include at least one of bentonite, cement, concrete, earth and sand, sand and soy gravel.

In an embodiment of the present invention, the step of installing the heat exchange pipe may include a heat exchange pipe formed of a double cylindrical structure in which a heat exchange medium is contained in the core portion and a phase stable phase change material is contained in the cladding portion.

According to the present invention, by using the phase stable phase change material as a grout material of the ground heat exchanger, it is possible to solve the problem of PCM converted into liquid during the phase change process, and to secure a high thermal conductivity. Therefore, the ground heat temperature can be stabilized and the thermal efficiency of the ground heat exchanger can be improved.

1 is a schematic diagram of a ground heat pump system according to the present invention.

2 is a cross-sectional view showing a state in which the underground heat exchanger of FIG. 1 is installed in the ground.

3 is a view showing the application of the SSPCM grout material of the ground heat exchanger according to an embodiment of the present invention.

Figure 4 is a view showing the application of the SSPCM grout material of the ground heat exchanger according to another embodiment of the present invention.

5 is a view showing the application of the SSPCM grout material of the ground heat exchanger according to another embodiment of the present invention.

6 is a cross-sectional view in the vertical direction and the longitudinal direction of the double heat exchange pipe of FIG. 5.

7 is a conceptual diagram showing the thermal efficiency of the underground heat exchanger according to the present invention.

8 is a flowchart illustrating a construction method of a ground heat exchanger according to an embodiment of the present invention.

DETAILED DESCRIPTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

1 is a schematic diagram of a ground heat pump system according to the present invention. 2 is a cross-sectional view showing a state in which the underground heat exchanger of FIG. 1 is installed in the ground.

The underground heat pump system, which is attracting much attention as a building renewable energy facility, is a combined cooling and heating system composed of a ground heat exchanger and a geothermal heat pump unit. The geothermal heat pump system is considered to be a highly efficient system because it utilizes the constant temperature of the underground which is hardly affected by the outside air. However, since the system efficiency is drastically reduced due to the increase in the ground temperature due to the heat dissipation in the summer and the decrease in the ground temperature due to the heat in the winter, the present invention maximizes the temperature and heat of the underground heat exchanger by utilizing PCM (Phase Change Materials).

1 and 2, the ground heat pump system 1 according to the present invention includes a ground heat exchanger 10 embedded in the ground. The underground heat exchanger (10) has a hollow formed in the middle, a pile (30) installed in the ground, a heat exchange medium, and a heat exchange pipe (100) and the heat exchange pipe (100) disposed in the hollow of the pile. The grout 200 is filled between the hollow inner surfaces to perform heat exchange with the heat exchange medium. The underground heat exchanger 10 may further include a container 200 formed in the pile 30 to cover the heat exchange pipe 100 and the grout 200.

In addition, the ground heat pump system (1) is for heating and cooling air-conditioning heat exchange between the heating and cooling fluid connected to the heat-exchange pipe 100 through which the heating and cooling fluid (cooling and heating fluid may be liquid or gas) for the heating and cooling of the building The heat pump 20 may be included. In the tube of the heat exchange pipe 100 may be provided with a valve in a position necessary to block or open the fluid flow.

In addition, the ground heat pump system 1 may be further provided with a solar heat collecting plate (not shown) and a heat storage tank (not shown) in order to restore the ground heat that is lost over time. Although omitted in the drawing, a discharge pipe, a circulation pipe, and the like connected to the inside of the pile 30 may be further installed.

For the construction of the underground heat exchanger 10, after forming a hole in the ground as a base material that is installed for the purpose of safely transferring the load of the building to the ground, a pile (30, pile) is installed. As the method of forming the hole, the LW method, the SGR method, and the JSP method may be used.

The pile 30 has a hollow 11 is formed in the middle, it may be used PHC pile. The container 200 may be further installed inside the pile 30. In the state where the heat exchange pipe 100 has passed through the upper surface of the container 200, the upper surface of the container 200 should be sealed, and the sealing method may use fusion between the tube and the upper surface.

The heat exchange pipe 100 has its own elasticity and may be formed in a U shape. However, the present invention is not limited thereto, and may be modified in various forms such as a coil shape, a straight shape, and a zigzag shape.

The heat exchange pipe 100 may be disposed inside the container 200 or in the hollow 11 of the pile 30. The grout 300 is filled in the gap between the outer surface of the container 200 and the inner surface of the hollow 11 so that heat exchange with the ground can be performed smoothly. When the grout 300 is filled in the gap between the outer surface of the container 200 and the inner surface of the hollow 11, compacting may be performed so that there is no gap in the grout 300 in order to facilitate heat transfer.

In addition, the grout 300 may also be filled in the inner space 22 of the container 200 or the pile 30, which is a space other than the heat exchange pipe 100, to increase thermal efficiency.

After the grout 300 is filled, a closing cap 13 is installed on the upper portion of the pile 30 to close the hollow 11 of the pile 30. Of course, the heat exchange pipe 100 extends out of the pile 30 through the closing cap 13. The closing cap 13 may be formed of a plate member through which a through hole through which the tube may pass and close the hollow 11.

The ground heat exchanger (10) is a costly part that takes up 50% of the total construction cost of the ground heat pump system (1), and is an important part that influences the performance of the ground heat pump system (1). The grout is a material that fills the gap between the drilled hole and the heat exchange pipe 100 of the underground heat exchanger 10, which accounts for 2 to 3% of the total construction cost of the underground heat pump system 1, but the thermal conductivity of the grout is 0.7 W / When doubled from mk to 1.4 W / mk, the ground heat conductivity is increased by about 15%, and the total length of the ground heat exchanger (10) required for the ground heat pump system (1) can be reduced by more than 30%. It is an important part.

The present invention applies Phase Change Materials (PCM) to grout in order to develop a ground heat pump system capable of securing a constant underground temperature throughout the year and regenerated using latent heat. The use of a phase change material is a feature that generates a large amount of heat in and out without a temperature change when the material changes phase. It absorbs heat as it melts when the ambient temperature rises and crystallizes when the temperature decreases. It is a material that repeats heat storage and heat radiation.

By using the heat storage effect of the PCM can be maximized the temperature and heat of the heat exchanger when combined with other heat sources, the ground heat pump system (1) according to the present invention is applied to PCM to maximize heat exchange efficiency and heat do. If the ground temperature is stabilized efficiently through the application of PCM, the system performance in long-term operation can be improved by more than 30% compared to the existing system, and the economic efficiency of the system can be improved by maximizing the amount of heat per hollow.

However, since the PCM has a problem of leaking the PCM converted into liquid during the phase change process and low thermal conductivity, the PCM cannot be applied as a grout material. Therefore, the shape stabilized phase change material (SSPCM) is used. Is used as grout material.

Hereinafter, embodiments of the present invention using a phase stable phase change material as a grout material will be described in detail.

In the present embodiment, the grout is formed by alternately stacking the first grout material 310 including the SSPCM and the second grout material 320 and the other grout material 320. The second grout material 320 may be formed of bentonite, cement, concrete, soil, sand, soybean, and the like, and may include all known grout materials.

During construction, the first grout material 310 and the second grout material 320 are poured into the drilling hole of the pile 30 installed in the ground or the hollow of the container 200, and then the heat exchange pipe 100. Can be buried. On the contrary, the first grout material 310 and the second grout material 320 may be poured after the heat exchange pipe 100 is installed in the drilling hole of the pile 30 or the hollow of the container 200. It may be. In addition, the heat exchange pipe 100 may be buried simultaneously with the lamination of the first grout material 310 and the second grout material 320.

The stacking order of the first grout material 310 and the second grout material 320 may be interchanged, and the stacking height of each section may be adjusted as necessary. According to the present exemplary embodiment, the first grout material 310 including the SSPCM and the second grout material 320 are stacked to form a grout, thereby preventing the SSPCM from leaking and increasing the thermal conductivity. In addition, the ground temperature is different from the upper layer and the lower layer, so that the SSPCM having a different melting point can be appropriately applied to each section, thereby increasing the heat storage performance to the maximum.

In this embodiment, the grout is formed by mixing a first grout material including SSPCM and a second grout material different from the first grout material. The second grout material may be formed of bentonite, cement, concrete, earth and sand, sand, soybean, and the like, and may include all known grout materials.

For example, the mixed grout material 330 may be manufactured by impregnating the second grout material into the second grout material. This is a similar principle to SSPCM applied to fine aggregates in concrete.

During construction, after the mixing grout material 330 is poured into the drilling hole of the pile 30 installed in the ground or the hollow of the container 200, the heat exchange pipe 100 may be embedded. On the contrary, the mixing grout material 330 may be poured after the heat exchange pipe 100 is installed in the drilling hole of the pile 30 or the hollow of the container 200. In addition, the heat exchange pipe 100 may be buried at the same time as the mixed grout material 330 is laminated.

5 is a view showing the application of the SSPCM grout material of the ground heat exchanger according to another embodiment of the present invention. 6 is a cross-sectional view in the vertical direction and the longitudinal direction of the double heat exchange pipe of FIG. 5.

In this embodiment, the grout material 340 may include the SSPCM, the heat exchange pipe 100 is formed in a double cylindrical structure, the SSPCM may be filled in the outer pipe.

Referring to FIG. 6A, a cross-sectional view in a vertical direction of the heat exchange pipe 100 of FIG. 5, in which a heat exchange medium is contained, and the SSPCM wraps around the core part 110 and the core part 110 formed at the center in the longitudinal direction. The filled cladding unit 130 is included. The heat exchange medium filled in the core part 110 may be a flowing gas or a fluid, for example, hot water. Since the SSPCM filled in the cladding unit 130 does not need to flow, it includes at least one partition wall.

Referring to FIG. 6B, a cross-sectional view of the heat exchange pipe 100 in FIG. 5 in a length direction, wherein the cladding unit 130 includes an SSPCM section 130a containing an SSPCM and a partition wall 130b for fixing the SSPCM. do.

As described above, the present invention applies a PCM fused grout having characteristics of high heat storage and high thermal conductivity by mixing SSPCM having high thermal conductivity with other grout materials. Through this, it is possible to secure heat amount of the underground heat pump system and to improve thermal efficiency.

Examples of SSPCM applicable to the present invention are as follows. First, the manufacturing method of SSPCM by combining with polymer, the manufacturing method of making SSPCM by mixing PCM with polymer, and second, PCM phase stabilization method through encapsulation, in this case, PCM exists in the capsule as encapsulated PCM On the outside, various materials such as silica play a role in wrapping PCM. Sesame, a method of manufacturing SSPCM by impregnating PCM with porous materials, as if the dough does not leak water. However, the present invention is not limited thereto, and various types of SSPCMs may be manufactured and applied to the ground heat exchanger.

According to the present invention, SSPCM is applied to the ground heat exchanger to efficiently stabilize the ground temperature and improve the performance of the ground heat pump system in the long term operation by more than 30%. Therefore, it is possible to improve the economics of the geothermal heat pump system by maximizing the amount of heat per hollow.

First, the pile or container in which the hollow is formed is embedded in the foundation position according to the construction of the building (step S110).

A grout comprising a first grout material comprising a shape stabilized phase change material (SSPCM) in the hollow is placed in the hollow of the perforation hole or container of the pile (step S130).

In the step of pouring the grout (step S130), the first grout material and the second grout material may be alternately stacked. The second grout material may include bentonite, cement, concrete, earth and sand, sand, soybean, and the like.

As another example, in the step of pouring the grout (step S130), the grout material formed by mixing the first grout material and the second grout material may be poured.

The heat exchange pipe containing the heat exchange medium is installed in the hollow in which the grout is poured (step S150).

In the step of installing the heat exchange pipe (step S150), the heat exchange medium may be installed in a double cylindrical structure in which a heat exchange medium is contained in the core portion and a phase-stable phase change material is contained in the cladding portion.

In this embodiment, the heat exchange pipe is installed after the grout is placed in the hole of the pile or the hollow of the container. Alternatively, the grout may be filled after inserting the heat exchange pipe into the hole of the pile or the hollow of the container. . In addition, the pipe may be installed in stages according to the degree of pouring grout.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the present invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

If the thermal efficiency of the geothermal heat pump system is improved, it is expected to bring significant energy savings and economic effects in Korea, which uses geothermal heat as well as revitalizing the construction market related to renewable energy. At present, domestic research and market related to PCM are not largely formed, and research on development of PCM fusion grout for geothermal heat pump system is considered to be insignificant. The potential of geothermal heat among the renewable energy resources available in Korea is very high. Recently, the interest and research on the ground heat pump system is growing, and the related market is expected to grow very much with the development of PCM fusion grout material.

Claims

A hollow formed in the center and installed in the ground;

A heat exchange pipe containing a heat exchange medium and disposed in the hollow of the pile; And

A grout filled between the heat exchange pipe and the hollow inner surface to perform heat exchange with the heat exchange medium,

Wherein the grout comprises a first grout material comprising a shape stabilized phase change material (SSPCM).
The method of claim 1,

The grout further comprises a second grout material,

The second grout material is at least one of bentonite, cement, concrete, earth and sand, sand and soybeans.
The method of claim 2,

The grout is a ground heat exchanger in which the first grout material and the second grout material are alternately stacked.
The method of claim 2,

The grout is a ground heat exchanger formed by mixing the first grout material and the second grout material.
The method of claim 1,

The heat exchange pipe is formed of a double cylindrical structure,

A core part containing a heat exchange medium therein and formed in the center of the longitudinal direction; And

An underground heat exchanger surrounding the core part and including a cladding part containing a phase stable phase change material.
The method of claim 5,

The cladding unit includes at least one partition wall for fixing the phase stable phase change material in the longitudinal direction.
The method of claim 1,

The phase stable phase change material includes at least one of a phase change material formed by mixing a phase change material in a polymer, a phase change material formed by impregnating the encapsulated phase change material, and a phase change material in a porous material.
Installing a pile having a hollow in the ground;

Placing a grout in the cavity comprising a first grout material comprising a shape stabilized phase change material (SSPCM); And

And installing a heat exchange pipe containing a heat exchange medium in the hollow in which the grout is poured.
The method of claim 8,

Pouring the grout,

The construction method of the underground heat exchanger which alternately laminates the said 1st grout material and the 2nd grout material.
The method of claim 8,

Pouring the grout,

The construction method of the underground heat exchanger which places the grout material formed by mixing the said 1st grout material and the 2nd grout material.
The method according to any one of claims 9 and 10,

The second grout material is a construction method of the underground heat exchanger comprising at least one of bentonite, cement, concrete, earth and sand, sand and soybean.
The method of claim 8,

Installing the heat exchange pipe,

A method of constructing an underground heat exchanger, in which a heat exchanger medium is formed in a core part and a heat exchanger pipe is formed in a double-cylindrical structure containing a phase-stable phase change material in a cladding part.