JP4869145B2 - Underground heat exchange system - Google Patents

Description

The present invention relates to a ground heat exchange system that suppresses fluctuations in the groundwater level due to a water blocking wall and is excellent in heat exchange efficiency in the ground.

While environmental issues such as global warming are attracting attention, the use of geothermal heat is being promoted as clean and safe thermal energy. Since geothermal heat is constant at about 15 to 16 ° C. throughout the year, it is used as a heat source for summer cooling and winter heating.

As a system using geothermal heat, pipes for refrigerant liquid circulation, etc. are embedded inside the concrete foundation piles that are driven deep into the bottom of the building foundation, and the refrigerant liquid is circulated to capture the geothermal heat around the foundation piles. There is a geothermal utilization device that exchanges and uses it as a heat source for air conditioning and hot water supply in a building (Patent Document 1).

In addition, by installing a shield wall in the shape of a weir in the ground downstream of the coil of underground water flow in which heat or cold heat circulates is embedded, and at least the upstream side opens to reach the impermeable layer There is a coil-type underground heat storage method that forms a stagnation part in which the flow of groundwater is suppressed and positions the coil in the stagnation part (Patent Document 2).
JP 2002-372314 A JP 2000-88481 A

However, in the geothermal utilization device described in Patent Document 1, heat exchange is performed with the refrigerant flowing in the pipe in the ground, but usually groundwater flows in the ground, and the flow of this groundwater is very slow. There is a problem that heat exchange with the groundwater per unit area is limited.

In particular, when constructing a structure, a water blocking wall is provided to prevent the ingress of groundwater, but the water blocking wall surrounds the structure basement, so there is no inflow of groundwater and heat exchange with the groundwater is not possible. . In this case, the pipe exchanges heat with the soil in the ground, but the soil has a problem that heat conduction is poor and heat exchange efficiency is poor. Furthermore, the structure becomes a barrier, and the difference in the groundwater level between the upstream side and the downstream side of the groundwater becomes large, which may affect the surrounding environment.

In addition, the method according to Patent Document 2 is a method of storing heat underground, and in order to prevent the heat storage effect from falling due to the flow of groundwater, it is a method of damming groundwater to create a stagnation part of groundwater. In order to store heat in the stagnation part, there is a problem that the amount of stored heat is determined by the amount of water staying at the heat exchange site, and there is a limit to heat exchange with the groundwater per unit time per unit area.

Moreover, since the flow of groundwater is blocked, the difference in the groundwater level between the upstream side and the downstream side of the groundwater becomes large, which may affect the surrounding environment.

This invention was made in view of such a problem, and it aims at providing the underground heat exchange system which is excellent in the heat exchange efficiency in the ground while suppressing the fluctuation | variation of the groundwater level by an underground continuous wall. To do.

In order to achieve the above-described object, the present invention provides an underground continuous wall provided to a position deeper than the groundwater level in the ground, a water inlet provided in the underground continuous wall, and groundwater of the underground continuous wall. A heat exchange means provided in the ground on the downstream side, wherein the heat exchange means exchanges heat with a groundwater flow passing through the water passage. .

The underground continuous wall is a water stop wall provided so as to surround the ground below the structure, and the water inlet is provided in a first water stop wall on the upstream side of the groundwater flow, and the first stop wall is provided. A drain outlet is provided in a second water stop wall provided to face the water wall, and the heat exchanging means is surrounded by the first water stop wall and the second water stop wall. It may be provided in the lower part of the object.

The heat exchange means may include a pipe, a water permeable layer covering the pipe, and a fluid flowing in the pipe, and the fluid may be circulated in the pipe.

Filtration means may be provided at the water passage.

In the present invention, since the groundwater blocked by the underground continuous wall can be caused to flow within the thickness of the permeable layer by the water inlet provided in the underground continuous wall, the groundwater flow velocity in the permeable layer that performs heat exchange Thus, it is possible to provide an underground heat exchange system that excels in heat exchange efficiency in the ground. In addition, since groundwater is not completely clogged, fluctuations in groundwater level due to underground underground walls can be suppressed.

ADVANTAGE OF THE INVENTION According to this invention, while suppressing the fluctuation | variation of the groundwater level by an underground continuous wall, the underground heat exchange system which can aim at the improvement of the heat exchange efficiency in underground can be provided.

Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a perspective view of the underground part of the underground heat exchange system according to the present embodiment, and FIG. 2 is a schematic diagram illustrating the overall configuration of the underground heat exchange system according to the present embodiment. The lower part of the ground 5 below the structure 1 is surrounded on all sides by a water blocking wall 3 that is a continuous underground wall. FIG. 1 is a perspective view of the water blocking wall with the illustration of the water blocking wall on the near side omitted. The water blocking wall 3 is provided to prevent the influence of groundwater in the installation work of the structure 1.

Usually, there is a flow in the groundwater (direction A in the figure), but a plurality of water inlets 9 are provided below the water blocking wall 3 on the upstream side of the flow of the groundwater. Further, a drain port 15 is provided below the water blocking wall 3 (downstream of the groundwater flow) facing the water blocking wall 3 provided with the water flow port 9. The water inlet 9 and the drain outlet 15 are provided below the groundwater level 7. Details of the water inlet 9 and the drain outlet 15 will be described later.

A concrete 13 and a pipe 11 are provided below the structure 1 surrounded by the water blocking wall 3. The pipe 11 is bent in the horizontal direction and is installed under the concrete 13 at substantially the same depth as the water inlet 9 and the drain outlet 15.

As shown in FIG. 2, in the lower part of the structure 1, groundwater flows in the direction A in the figure, passes through a water inlet 9 provided at a position deeper than the groundwater level 7 of the water blocking wall 3, 11 flows into the vicinity. A fluid that substantially exchanges heat is circulated through the pipe 11 by the pressure feeding device 17.

The groundwater that flows into the vicinity of the pipe 11 exchanges heat with the fluid in the pipe 11. Here, since the temperature of groundwater is constant at 15 to 16 ° C. throughout the year, it can be used as a heat source for cooling in summer and heating in winter.

The fluid subjected to heat exchange is sent to the ceiling radiation panel 21 or the fan coil unit 23 installed in the room of the structure 1 via the heat pump 18 or directly, and the temperature of the room is adjusted. As the fluid, for example, water or brine can be used.

FIG. 3 is a diagram showing details of the vicinity of the installation position of the pipe 11 below the structure 1. The water blocking wall 3 is provided to a depth that reaches the water-impermeable layer 17 below the structure 1. In the lower part of the structure 1 surrounded by the water blocking wall 3, concrete 16 that is a so-called waste container is provided.

A pipe 11 is installed on the concrete 16. Since the part where the pipe 11 is installed is a permeable layer 19 such as a gravel layer, the groundwater can flow without receiving a large resistance. Concrete 13 is provided on the water permeable layer 19.

The water inlet 9 is provided at the depth of the water permeable layer 19 of the water blocking wall 3. That is, the groundwater flowing into the lower part of the structure 1 from the water flow port 9 flows through the water permeable layer 19 in which the pipe 11 is disposed, and the thickness of the water permeable layer 19 becomes a flow path of the ground water.

Here, the flow of groundwater is usually about 10 ⁻⁵ m / s. Therefore, the distance that flows in one day is less than 1 m, and there is almost no flow. Therefore, when a heat exchanger is installed in such a groundwater flow, there is a limit to the amount of heat exchange per unit time and unit area due to the heat capacity due to the amount of groundwater. For this reason, in order to obtain a larger heat exchange efficiency, it is desirable to obtain a larger flow rate of groundwater.

In the underground heat exchange system according to the present embodiment, groundwater for heat exchange flows into the pipe 11 installation position, which is a heat exchange position, from the water inlet 9. Here, since the water inlet 9 is provided at a position deeper than the groundwater level 7, the amount of groundwater from the impermeable layer 17 to the groundwater level 7 can be introduced from the water inlet 9.

That is, since the groundwater blocked by the water blocking wall 3 can flow within the thickness of the permeable layer 19, the flow rate of the groundwater passing through the permeable layer 19 is remarkably improved as compared with the normal flow rate of the groundwater.

For example, when the groundwater level upstream of the groundwater of the structure 1 is 7 m and the water inlet 9 and the water permeable layer 19 having a thickness of 20 cm are provided at a position 10 m underground, the flow rate of the groundwater passing through the water permeable layer 19 is It is about 15 times the normal groundwater flow rate.

FIG. 4 is a plan view of the water permeable layer 19 provided with the pipe 11 as viewed from above. The water permeable layer 19 is surrounded on all sides by the water blocking wall 3. A plurality of water inlets 9 are provided in the water blocking wall 3 on the upstream side of the groundwater, and groundwater flows from the water inlet 9 into the permeable layer 19 (direction A in the figure). The pipe 11 is bent and disposed in the water permeable layer 19, and heat exchange is performed by heat transfer between the pipe 11 and the groundwater in the water permeable layer 19. After the heat exchange, the groundwater flows out of the water blocking wall 3 from the drain port 15 facing the water inlet 9 (direction B in the figure).

For example, a steel pipe having an outer diameter of about 30 mm can be used as the pipe 11. Moreover, the pipe 11 does not need to be connected by one, and a plurality of pipes 11 may be provided side by side. This is because if one pipe 11 is too long, the pressure loss of the fluid flowing inside becomes large. In this case, a plurality of pipes 11 may be arranged in the water permeable layer 19 and merged in the vicinity of the pressure feeding device 17.

FIG. 5 is an enlarged view of the water passage 9. Groundwater flows from the lower direction in the figure (direction A in the figure), passes through the water passage 9, and flows into the permeable layer 19. The water passage 9 is filled with gravel 25, and a filtration means 27 is provided on the water permeable layer 19 side.

The gravel 25 is intended to prevent surrounding earth and sand from flowing into the water passage 9 due to the groundwater flow and blocking the water passage 9. The filtering means 27 is a filter such as a metal mesh or non-woven fabric, for example, and prevents the gravel 25 or earth and sand from flowing into the water permeable layer 19 due to the groundwater flow. The drain port 15 may have a similar structure.

A plurality of water inlets 9 are provided on the water blocking wall on the upstream side of the groundwater. However, if the number and size of the water inlets 9 (that is, the total opening area) are too small, the resistance at the time of inflow of groundwater becomes too large, and the inflow of groundwater The amount is limited. Furthermore, the amount of water corresponding to the groundwater level 7 cannot be efficiently introduced into the permeable layer 19, and a part of the groundwater goes around to the left and right of the structure 1, reducing the amount of groundwater that can be effectively used for heat exchange.

For this reason, it is preferable that the number of water inlets 9 is large so that the resistance of the flow of groundwater does not become excessive. Moreover, the water flow opening 9 may not be a round hole shape, but may be a square hole or a slit shape. Although the size of the water flow opening 9 depends on the permeable layer 19 and the groundwater level, it can be set to, for example, about 20 cm to 100 cm. The drain ports 15 are preferably the same size and the same number as the water flow ports 9, but the size and number of the drain ports 15 may be changed so as not to cause resistance to the groundwater flow.

As described above, according to the present embodiment, the water inlet 9 and the drain outlet 15 are provided on the upstream side and the downstream side of the groundwater, respectively. For this reason, the water level difference between the upstream groundwater level and the downstream groundwater level caused by the water blocking wall 3 is reduced. That is, the rise in the water level on the upstream side of the ground water and the decrease in the water level on the downstream side of the ground water due to the construction of the structure 1 can be mitigated. Therefore, adverse effects on the surrounding environment associated with the construction of the structure 1 can be suppressed.

Further, the water inlet 9 provided in the water blocking wall 3 is provided at substantially the same depth as the pipe 11 which is a heat exchange part provided in the lower part of the structure 1. For this reason, groundwater can be efficiently introduced into the permeable layer 19 in which the pipe 11 is installed. Therefore, the pipe 11 that performs heat exchange can exchange heat with the groundwater, not with soil with poor heat conduction.

The water inlet 9 is provided at a position sufficiently deeper than the groundwater level 7 and can flow the amount of water corresponding to the groundwater level 7 to the thickness of the permeable layer 19, thereby increasing the groundwater flow velocity in the permeable layer 19. Can do. Therefore, compared to the conventional method of exchanging heat by damming groundwater and the method of exchanging heat at the natural flow rate of groundwater, the heat transfer rate is improved and the heat capacity of the groundwater is increased. By the increase, the heat exchange efficiency between the groundwater and the pipe 11 can be remarkably increased.

The water inlet 9 is provided with a gravel 21 and a metal mesh or non-woven fabric as the filtering means 27, so that there is no inflow of earth and sand due to the groundwater flow, and there is no blockage of the water inlet 9. Therefore, high heat exchange efficiency is maintained over a long period of time.

According to such a high-efficiency underground heat exchange system, it is possible to reduce CO ₂ emissions associated with energy consumption reduction in air conditioning in summer and winter, and to suppress heat island by not releasing cooling exhaust heat to the atmosphere. Can be expected.

Next, the underground heat exchange system according to the second embodiment will be described. Note that, in the second embodiment, the same numbers as those shown in FIGS. 1 to 5 are used for constituent elements that perform the same functions as those in the first embodiment, and a duplicate description is avoided.

FIG. 6 is a perspective view of the underground portion of the underground heat exchange system according to the second embodiment, and FIG. 7 shows details of the vicinity of the pipe 11 installation position of the underground heat exchange system according to the second embodiment. FIG. The underground heat exchange system according to the second embodiment uses a general underground continuous wall 31. The underground continuous wall 31 is provided so as to reach the impermeable layer 17 in the underground. As the underground continuous wall 31, for example, a groundwater purification structure provided to prevent contaminants flowing out from the structure 29 or the like from mixing into the groundwater and diffusing, or groundwater used in the structure 29 or the like. Underground dam for water storage.

The underground continuous wall 31 is provided with a plurality of slit-shaped water inlets 9 for the purpose of purifying groundwater and alleviating the difference in groundwater level before and after the underground continuous wall 31. The water inlet 9 is provided at a position deeper than the groundwater level 7 in order to flow groundwater to the groundwater downstream side of the underground continuous wall 31. The water inlet 9 is filled with a water-permeable purification material for purifying groundwater, gravel for filtering earth and sand, and the like. Further, a filtration means 27 such as a metal mesh or a non-woven fabric can be provided on the outlet side of the water passage 9.

A permeable layer 19 is provided on the downstream side of the underground water of the underground continuous wall 31, and a pipe 11 is provided in the permeable layer 19. The lower part of the permeable layer 19 is the impermeable layer 17, and the upper part of the permeable layer 19 is filled with earth and sand.

The groundwater that has passed through the lower part of the structure 29 flows to the underground continuous wall 31 by the groundwater flow (direction A in the figure), and flows into the water inlet 9 provided in the underground continuous wall 31. The groundwater that has flowed into the water inlet 9 flows into the permeable layer 19 and exchanges heat with the pipe 11. The groundwater after the heat exchange flows directly downstream as a groundwater flow.

In addition, the flow path of the groundwater that has passed through the water inlet 9 includes not only the inside of the permeable layer 19 but also the earth and sand portion above the permeable layer 19. However, since the permeable layer 19 is composed of gravel or the like, the resistance to groundwater flow is extremely small compared to the surrounding earth and sand. Therefore, most of the groundwater that has passed through the water inlet 9 has priority in the permeable layer 19 over the surrounding earth and sand. Then flow. That is, since a sufficient groundwater flow velocity can be obtained in the permeable layer 19, good heat exchange efficiency can be achieved.

The refrigerant in the pipe 11 that has exchanged heat with the groundwater is circulated by a pumping device 17 (not shown) provided on the ground, and heat is recovered by the heat pump 18 or the like. In the present embodiment, the position of the structure where heat is actually used is not limited to the ground above the pipe 11. For example, even in a structure 29 or the like located at a location away from the underground continuous wall 31, the heat exchanged by the pipe 11 can be used. In this case, the pipe 11 may be extended to the structure 29.

Thus, according to the underground heat exchange system concerning 2nd Embodiment, the effect similar to the underground heat exchange system concerning 1st Embodiment can be acquired. Moreover, when the structure is simple and there is no structure in the upper part, it is easy to use the existing underground continuous wall.

As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

For example, in the present embodiment, the structure 1 has a rectangular cross-sectional shape, and the water blocking wall 3 is provided so as to surround the four sides of the structure 1, but the water blocking wall 3 may be circular. Absent. In this case, the water inlet 9 may be provided in the semicircular portion of the water blocking wall 3 on the upstream side of the ground water, and the drain port 15 may be provided in the semicircular portion on the downstream side of the groundwater.

The perspective view in the underground part of the underground heat exchange system which concerns on 1st Embodiment. Schematic which shows the whole structure of the underground heat exchange system concerning 1st Embodiment. Detailed view of the vicinity of the installation position of the pipe 11 at the lower part of the structure 1. The top view which looked at the water-permeable layer 19 in which the pipe 11 was installed from upper direction. The enlarged view of the water inlet 9. FIG. The perspective view in the underground part of the underground heat exchange system which concerns on 2nd Embodiment. The detailed figure of the pipe 11 installation position vicinity of the underground heat exchange system which concerns on 2nd Embodiment.

Explanation of symbols

1 ......... Structure 3 ......... Water blocking wall 5 ......... Ground 7 ......... Ground water level 9 ......... Water inlet 11 ......... Pipes 13, 16 ......... Concrete 15 ......... Drain 17 ... ...... Pressure feeding device 18 ......... Heat pump 19 ......... Water-permeable layer 21 ......... Ceiling radiation panel 23 ......... Fan coil unit 25 ......... Gravel 27 ... …… Filter means 29 ......... Structure 31 ... …… Underground continuous wall

Claims (4)

Underground continuous wall provided deeper than the groundwater level in the ground,
A water outlet provided in the underground continuous wall;
Heat exchange means provided in the ground downstream of the underground continuous wall of the underground water flow;
Have
The underground heat exchange system, wherein the heat exchange means exchanges heat with a groundwater flow passing through the water passage. The underground continuous wall is a water blocking wall provided so as to surround the ground below the structure,
The water inlet is provided in the first water stop wall upstream of the groundwater flow,
A drain port is provided in the second water stop wall provided to face the first water stop wall,
2. The underground heat exchange system according to claim 1, wherein the heat exchange means is provided at a lower portion of the structure surrounded by the first water stop wall and the second water stop wall. The heat exchange means includes
Pipes,
A water permeable layer covering the pipe;
Fluid flowing in the pipe;
The ground heat exchange system according to claim 1, wherein the fluid is circulated in a pipe. The underground heat exchange system according to claim 1, wherein the water inlet is provided with a filtering means.

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