JP6138475B2 - Underground heat exchanger - Google Patents

Description

  The present invention relates to a geothermal heat exchanger that uses geothermal heat.

  As a system equipped with the above-mentioned underground heat exchanger, there are many systems that use groundwater as a heat source (for heating or cooling) by pumping groundwater from the viewpoint of good heat exchange efficiency and low equipment cost. Proposed. In addition, in this type of system, in order to suppress ground subsidence due to groundwater pumping, a number of systems configured to reduce the groundwater pumped back to an underground aquifer have been proposed (for example, JP 2002-54857, JP-A-2004-317102, etc.).

JP 2002-54857 A JP 2004-317102 A

  However, especially in areas where there is a high concern about land subsidence, strict pumping regulations are set by law regardless of whether the pumped-up groundwater is returned to the underground aquifer or not. In particular, installation may be prohibited depending on apparatus specifications such as the discharge port cross-sectional area. In other words, in some areas, strict regulations are provided for the provision of “wells” or “pumping facilities”. For this reason, the conventional system of this type has a problem that a desired performance cannot be obtained because a device having a desired specification cannot be installed, or the scale must be reduced. Even in the case where this type of system is installed in an area where there is no restriction on pumping, there is a demand for further improving the heat exchange efficiency in view of further demand for energy saving in recent years.

  The present invention has been made in view of the above-described circumstances. That is, an object of the present invention is to provide an underground heat exchanger capable of performing heat exchange with higher efficiency.

  The underground heat exchanger according to the present invention includes a casing, a lid, and a heat exchange unit.

  The casing is a cylindrical member and is formed so that at least one end is opened (typically, both ends are opened). The casing is embedded in a vertical hole excavated in the ground such that the upper end on the ground surface side which is the one end is opened. Moreover, the mesh part which the groundwater as a heat source can pass is formed in this casing. This mesh part is provided at least at the lower end (the end opposite to the one end) corresponding to the underground aquifer. The mesh portion may be provided above the lower end portion of the casing. In this case, the plurality of mesh portions may be provided so as to correspond to each of the plurality of underground aquifers having different depths.

  The lid is attached to the opening so as to close the opening at the upper end of the casing. This lid is typically a plate-like member and is provided so as to close the opening in a substantially sealed state.

  The heat exchange part is a tubular member. Typically, the heat exchange part is a U-shaped tube having a longitudinal direction along the axial direction of the casing, and is provided so that a portion bent in a U-shape serves as a bottom. The heat exchanging portion is accommodated in a space inside the casing so as to penetrate the lid and reach the depth of the mesh portion provided at the lower end portion of the casing. . The heat exchanging section allows the outer surface to come into contact with the groundwater and flow while the heat medium is accommodated in a liquid-tight manner (that is, so as not to leak to the groundwater side). It is comprised so that the heat exchange between the said groundwater in the said space inside and the said heat medium may be performed.

The feature of the present invention resides in that the underground heat exchanger further includes a fluid blowing pipe, a fluid pumping means, a pressure adjusting means, and a fluid return means .

  The fluid blowing pipe is a tubular member housed in the space inside the casing, and penetrates the lid body and has a depth of the bottom portion in the heat exchange portion (that is, at the lower end portion in the casing). It is provided so as to reach the depth of the provided mesh portion). The fluid blowing pipe has a fluid ejection opening. The fluid ejection opening is formed so as to blow the fluid into the groundwater in the space inside the casing by ejecting a fluid in the vicinity of the bottom of the heat exchange unit.

  The fluid pumping means is connected to an end of the fluid blowing pipe opposite to the fluid ejection opening so as to send the fluid to the fluid blowing pipe. Note that gas or liquid may be used as the fluid. As the gas, for example, (compressed) air or inert gas (nitrogen gas, argon gas, etc.) can be suitably used. When gas is used as the fluid, the fluid blowing pipe, the fluid ejection opening, and the fluid pumping means may be referred to as a gas blowing pipe, a gas ejection opening, and a gas pumping means, respectively. In particular, when (compressed) air is used as the fluid, the fluid blowing pipe, the fluid ejection opening, and the fluid pumping means may be referred to as an air blowing pipe, an air ejection opening, and a pneumatic feeding means, respectively.

Flow body reflux means is provided so as to reflux the fluid to the fluid pumping means from the space inside the casing. Specifically, for example, when a gas is used as the fluid, the fluid recirculation means is below the lid in the space inside the casing and above the water level (hereinafter referred to as “upper space”). .) To the fluid pressure feeding means so as to recirculate (circulate) the gas. In this case, the fluid pumping means sends out the gas as the fluid to the fluid blowing pipe, including the gas refluxed by the fluid refluxing means. In this case, the fluid reflux means may be referred to as a gas reflux means or an air reflux means.

  The pressure adjusting means is provided so as to adjust the gas pressure in the space inside the casing, that is, in the upper space. Specifically, for example, the pressure adjusting means may be provided as a gas passage such as a through hole formed in the lid. Alternatively, the pressure adjusting means includes a gas exhaust pipe and a pressure regulating valve. The gas exhaust pipe is provided so as to allow the upper space and the outside (outside air on the ground surface side) to communicate with each other by penetrating the lid. The pressure regulating valve is attached to the gas discharge pipe. In addition, when (compressed) air is used as the fluid, the gas discharge pipe may also be referred to as an air discharge pipe.

  In the underground heat exchanger of this invention which has this structure, the said heat medium flows in into the said heat exchange part by supplying the said heat medium to the said heat exchange part. On the other hand, the heat medium that has undergone heat exchange with the groundwater in the heat exchange unit is discharged from the heat exchange unit and supplied to various devices (heat pump, snow melting device, etc.) that use heat. Here, in the structure of the underground heat exchanger of the present invention, heat exchange in the heat exchange section is performed as follows.

  The outer surface of the heat exchange part contacts the groundwater housed in the space inside the casing. At the same time, the heat medium (which is liquid-tightly accommodated in the heat exchange portion so as not to leak from the heat exchange portion to the groundwater side) passes through the heat exchange portion. Shed. Thereby, heat exchange between the groundwater and the heat medium is performed via the heat exchange section.

  At this time, in the present invention, when the fluid is blown into the groundwater from the fluid ejection opening in the fluid blowing pipe, the groundwater in the vicinity of the outer surface in the heat exchange section flows well (convection, (It can also be called stirring or circulation). In this case, the mode of heat exchange between the groundwater and the heat medium is “forced convection”, unlike the conventional “natural convection”. Therefore, according to the present invention, the heat exchange efficiency is improved as compared with the prior art.

  Specifically, for example, when a gas is used as the fluid, bubbles are generated in the groundwater by blowing the gas as the fluid into the groundwater from the fluid ejection opening in the fluid blowing pipe. The bubbles are generated in the vicinity of the bottom of the heat exchange unit, and then rise in the space inside the casing. That is, bubbles rise in the groundwater stored in the space inside the casing and facing (contacting) the outer surface of the heat exchange unit. As the bubbles rise, the groundwater in the vicinity of the outer surface in the heat exchange section flows well. Therefore, in this case, the heat exchange efficiency is significantly improved as compared with the conventional case.

  Further, while the fluid is blown from the fluid ejection opening, the pressure adjusting means adjusts the gas pressure in the space inside the casing (in the upper space). For this reason, the ejection of the groundwater from the opening at the upper end of the casing is satisfactorily suppressed. That is, according to the configuration of the present invention, particularly when gas is used as the fluid, highly efficient heat exchange can be realized without pumping the groundwater to the ground. Therefore, in such a case, the underground heat exchanger according to the present invention does not fall under “well” or “pumping equipment”, so that the desired performance and specifications can be achieved even in an area where strict pumping regulations are set. Things can be installed.

  In addition, when the plurality of mesh portions are provided so as to correspond to the underground aquifers having different depths, the flow (circulation) of the groundwater in the space inside the casing is even better. To be done. Therefore, in this case, the heat exchange efficiency is further improved.

  By the way, when a gas is used as the fluid, the temperature of the gas blown into the groundwater is rising in the groundwater (even if it is around the outside temperature at the beginning of being ejected from the fluid ejection opening) It gradually changes to the temperature of the groundwater. Then, the gas whose temperature has been changed closer to the groundwater is then retained in the upper space. Then, the temperature of the gas staying in the upper space is between the outside air temperature and the temperature of the groundwater in the vicinity of the underground aquifer during the operation of the underground heat exchanger.

  In this regard, when the fluid return means is provided, the gas staying in the upper space (having a temperature closer to the temperature of the groundwater than the outside air temperature) is transferred to the fluid pressure sending means by the fluid return means. Is refluxed (delivered). Thus, the gas recirculated from the upper space to the fluid pumping means is sent to the fluid blowing pipe by the fluid pumping means. That is, in such a configuration, at least a part of the gas ejected from the fluid ejection opening is circulated between the upper space and the fluid pumping means.

  In this way, by returning the gas in the upper space to the fluid pumping means, the temperature of the gas in the upper space is in the vicinity of the underground aquifer during the operation of the underground heat exchanger. It gets closer to the temperature of the groundwater. Then, the temperature of the gas sent out to the fluid blowing pipe by the fluid pumping means and ejected from the fluid ejection opening becomes closer to the temperature of the groundwater in the vicinity of the underground aquifer. Therefore, according to such a configuration, a part of the heat to be exchanged between the groundwater and the heat medium is favorably suppressed from being consumed for heat exchange between the heat medium and the gas (bubbles). Thus, the heat exchange efficiency is further improved. Even when a liquid is used as the fluid, a similar effect can be expected by refluxing.

It is a sectional side view showing the schematic structure of the underground heat exchanger concerning one embodiment of the present invention. It is a sectional side view which shows schematic structure of the modification of the underground heat exchanger shown by FIG. It is a sectional side view which shows schematic structure of the other modification of the underground heat exchanger shown by FIG. It is a sectional side view which shows schematic structure of another modification of the underground heat exchanger shown by FIG. It is a sectional side view which shows schematic structure of another modification of the underground heat exchanger shown by FIG. It is a sectional side view which shows schematic structure of another modification of the underground heat exchanger shown by FIG.

<Configuration>
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment in which the invention is embodied will be described with reference to the drawings (variation examples are described at the end). As shown in FIG. 1, a vertical hole 11 is excavated in the ground 10. In the present embodiment, the ground 10 has a lower aquifer 13, a hardly permeable layer 14, an upper aquifer 15, and an upper non-aquifer 16 in order from the surface 12. The vertical hole 11 is formed to a depth reaching the lower aquifer 13. Moreover, in this embodiment, since the groundwater 17 is not pumped up from the vertical hole 11, the water level 18 in the said vertical hole 11 is formed so that it may correspond with a natural water level substantially. An upper space 19 is formed in the space inside the vertical hole 11 and above the water level 18 (that is, between the ground surface 12 and the water level 18).

  The underground heat exchanger 20 according to the embodiment of the present invention includes a casing 21, a lid body 22, a heat exchange unit 23, a fluid blowing pipe 24, a fluid pressure feeding means 25, a pressure adjusting means 26, and a control. Part 27.

  The casing 21 is a cylindrical member having a longitudinal direction along the central axis C, and is embedded in the vertical hole 11 so that the central axis C is substantially parallel to the vertical direction. In the present embodiment, the casing 21 is formed so that both end sides in the longitudinal direction are open. In the space inside the casing 21, earth and sand and gravel are not accommodated, while ground water 17 is accommodated as a heat source that forms a water level 18 that substantially matches the natural water level.

  A lid 22 is attached to an upper end opening 211 that is an opening on the ground surface 12 side of the casing 21. The lid body 22 is a substantially circular plate-like member in plan view, and is formed so as to close the upper end opening 211 in a substantially sealed state (that is, airtight). Further, a locking portion 212 for locking the lid body 22 is provided in the vicinity of the upper end opening 211 in the casing 21 so as to protrude toward the space inside the casing 21.

  A mesh portion 215 is provided at a position corresponding to the lower aquifer 13 on the lower end 213 of the casing 21 (the end on the lower end opening 214 side). A large number of mesh openings 216 that are through-holes through which groundwater 17 can pass while solids such as earth and sand are difficult to pass are formed in mesh portion 215. In the present embodiment, the mesh portion 215 is also provided at a position above the lower end portion 213 of the casing 21 and corresponding to the upper aquifer 15. That is, the plurality of mesh portions 215 are provided to correspond to the plurality of underground aquifers having different depths.

  The heat exchanging portion 23 is a U-shaped tube having a longitudinal direction along the central axis C, and a bent portion 231 which is a portion bent in a U shape is a bottom portion of the mesh portion 215 in the lower end portion 213 of the casing 21. While reaching the depth, the end opposite to the bent portion 231 is provided so as to penetrate the lid body 22. That is, the heat exchange part 23 is accommodated in the space inside the casing 21 so that most of the heat exchange part 23 is immersed in the groundwater 17. Note that the joint between the through-hole formed in the lid 22 for penetrating the heat exchanging portion 23 and the outer wall surface 232 of the heat exchanging portion 23 is closed in a substantially sealed state (that is, airtight). Yes.

  Inside the heat exchanging portion 23, a heat medium passage 233 is formed, which is a space for allowing a liquid heat medium H (brine or the like) to flow while being stored in a liquid-tight manner. In the heat exchanging unit 23, the ground water 17 comes into contact with the outer wall surface 232 of the tube wall 234 made of corrosion-resistant metal such as stainless steel, and the heat medium H flows through the heat medium passage 233 inside the tube wall 234. Thus, the heat exchange between the groundwater 17 and the heat medium H is performed via the pipe wall 234.

  The fluid blowing pipe 24 is a tubular member whose one end side (blowing pipe lower end portion 241 side) is closed, and the blowing pipe lower end portion 241 has a depth (that is, heat) of the mesh portion 215 in the lower end portion 213 of the casing 21. The depth of the bent portion 231 in the replacement portion 23), and the connecting portion 242 that is the end opposite to the lower end portion 241 of the blow pipe penetrates the lid body 22 and protrudes to the outside (the ground surface 12 side). It is provided to do. The connecting portion 242 is connected to a fluid pumping means 25 (provided with a compressor or the like) for sending compressed air to the fluid blowing pipe 24. In addition, the joint part of the through-hole formed in the cover body 22 in order to penetrate the fluid blowing pipe 24 and the outer wall surface of the fluid blowing pipe 24 is closed in a substantially sealed state (that is, airtight). .

  Furthermore, a large number of through holes (fluid ejection openings 243) are formed on the side surface of the blow pipe lower end 241. The fluid ejection opening 243 is provided so as to blow air into the groundwater 17 in the space inside the casing 21 by ejecting air in the vicinity of the bottom (bending portion 231) in the heat exchanging portion 23. That is, the fluid blowing pipe 24 generates a large number of bubbles in the vicinity of the bottom (bending portion 231) in the heat exchanging portion 23 by ejecting the compressed air supplied by the fluid pumping means 25 from the fluid ejection opening 243. It is configured as follows.

  The pressure adjusting means 26 adjusts the pressure of gas (air) in the upper space 19 (hereinafter simply referred to as “upper space 19”) inside the casing 21 and below the lid body 22, thereby allowing the groundwater 17 to be adjusted. It is provided so as to suppress (prevent) jetting to the surface 12 side. The control unit 27 is a so-called control panel having a microcomputer, switches, and the like, and is provided so as to control the operation state of the entire underground heat exchanger 20.

  In the present embodiment, specifically, the pressure adjusting means 26 includes a gas discharge pipe 261 and a pressure regulating valve 262. The gas discharge pipe 261 is a tubular member and is provided so as to penetrate the lid body 22. In addition, the joint part of the through-hole formed in the cover body 22 in order to penetrate the gas exhaust pipe 261 and the outer wall surface of the said gas exhaust pipe 261 is obstruct | occluded in the substantially sealed state (namely, airtight). . The gas exhaust pipe 261 is provided such that one end portion opens in the upper space 19 and the other end portion opens on the outside (the ground surface 12 side). The pressure regulating valve 262 is a so-called automatic air vent valve that automatically opens at a predetermined pressure, and is mounted near the end of the gas exhaust pipe 261 on the outside air side.

In the present embodiment, the pressure adjusting means 26 further includes an auxiliary gas discharge pipe 263 and a safety valve 264 in order to more reliably prevent the groundwater 17 from being ejected to the surface 12 side. The auxiliary gas discharge pipe 263 is also a tubular member like the gas discharge pipe 261, and is provided so as to allow communication between the upper space 19 and the outside (outside air on the ground surface 12 side). The safety valve 264 is a valve that operates at a predetermined pressure higher than the valve opening pressure of the pressure regulating valve 262, and is mounted near the end of the auxiliary gas discharge pipe 263 on the outside air side.
<Action and effect>
In the underground heat exchanger 20 of this embodiment having such a configuration, the heat medium H flows into the heat exchanging part 23 by supplying the heat medium H to the heat exchanging part 23. On the other hand, the heat medium H that has undergone heat exchange with the groundwater 17 in the heat exchange unit 23 is discharged from the heat exchange unit 23 and supplied to various devices (such as a heat pump and a snow melting device) that use heat. Here, the heat exchange in the heat exchange part 23 is performed as follows.

  The outer wall surface 232 of the tube wall 234 in the heat exchanging portion 23 comes into contact with the groundwater 17 accommodated in the space inside the casing 21. At the same time, the heat medium H flows through the heat medium passage 233 inside the tube wall 234. Thereby, heat exchange between the groundwater 17 and the heat medium H is performed through the tube wall 234 in the heat exchange unit 23.

  At this time, gas (air) is blown into the groundwater 17 from the fluid ejection opening 243 in the fluid blowing pipe 24, thereby generating bubbles in the groundwater 17. The bubbles are generated in the vicinity of the bottom of the heat exchanging portion 23 (in the vicinity of the bent portion 231), and thereafter rise in the space inside the casing 21 toward the upper space 19. That is, the bubbles rise in the groundwater 17 stored in the space inside the casing 21 and facing (contacting) the outer wall surface 232 in the heat exchange section 23. As the bubbles rise, the groundwater 17 in the vicinity of the outer wall surface 232 in the heat exchanging portion 23 flows favorably (also referred to as convection, stirring, or circulation). In this case, the mode of heat exchange between the groundwater 17 and the heat medium H is “forced convection”, unlike the conventional “natural convection”. Furthermore, the effect that the water level 18 of the groundwater 17 rises from the natural water level (slight amount within a range in which the groundwater 17 does not overflow on the surface 12 side) by blowing air into the groundwater 17 can be expected. The area that contributes to heat exchange in the outer wall surface 232 is increased. Therefore, according to such a configuration, the heat exchange efficiency is significantly improved as compared with the conventional case.

  In particular, in winter, when the outside air temperature is low, bubbles generated at the fluid ejection opening 243 are expanded by receiving heat from the relatively high temperature groundwater 17. Then, the rise of the bubbles is promoted, and thereby the flow of the groundwater 17 is also promoted. Therefore, even if the output of the fluid pumping means 25 is relatively reduced, good heat exchange efficiency can be achieved. On the other hand, in summer when the outside air temperature is high, by adopting a material with good heat insulation as the material of the fluid blowing pipe 24, a relatively high temperature is coupled with a slight increase in temperature due to compression at the time of pumping by the fluid pumping means 25. Can be ejected from the fluid ejection opening 243. Thereby, relatively high-temperature bubbles are generated in the vicinity of the bottom portion in the heat exchanging portion 23, and thus heat exchange between the groundwater 17 and the heat medium H in the vicinity of the bottom portion in the heat exchanging portion 23 is favorably promoted. .

  Furthermore, in this embodiment, the some mesh part 215 is provided so that it may respond | correspond to the lower aquifer 13 and the upper aquifer 15 from which depth differs, respectively. Thereby, the flow (circulation) of the groundwater 17 is favorably performed in the space inside the casing 21. Therefore, the heat exchange efficiency is further improved than before.

  By the way, the pressure of the air in the upper space 19 increases due to the blowing of air from the fluid ejection opening 243. In this regard, in the configuration of the present embodiment, when the pressure of the air in the upper space 19 reaches a predetermined pressure, the pressure regulating valve 262 is automatically opened. Thereby, the pressure of the air in the upper space 19 is appropriately adjusted so as to be suppressed below the predetermined pressure. Further, even when the pressure of the air in the upper space 19 suddenly increases or the pressure regulating valve 262 breaks down, it automatically opens at a predetermined pressure higher than the valve opening pressure of the pressure regulating valve 262. Since the safety valve 264 is provided, an excessive increase in pressure is well prevented. For this reason, the ejection of the groundwater 17 from the upper end opening 211 in the casing 21 is satisfactorily suppressed. That is, according to the configuration of the present embodiment, highly efficient heat exchange can be realized without pumping the groundwater 17 to the ground. Therefore, the underground heat exchanger 20 according to the present embodiment does not fall under “well” or “pumping equipment”, so that it has a desired performance and specification even in an area where strict pumping regulations are set. It becomes possible to do.

<Modification>
It should be noted that the above-described embodiments are merely examples of typical embodiments of the present invention that the applicant has considered to be the best at the time of filing of the present application. Therefore, the present invention is not limited to the above-described embodiment. Therefore, it goes without saying that various modifications can be made to the above-described embodiment within the scope not changing the essential part of the present invention.

  Hereinafter, some typical modifications will be exemplified. In the following description of the modified examples, the same reference numerals as those in the above embodiment can be used for members having the same configuration and function as those described in the above embodiment. And about description of this member, the description in the above-mentioned embodiment shall be used in the range which is not technically consistent. Needless to say, the modifications are not limited to those listed below. In addition, all or a part of the configuration of the above-described embodiment and the plurality of modified examples may be applied in a composite manner as appropriate within a technically consistent range.

  In the casing 21, only the upper end opening 211 is open, while the edge on the lower end 213 side (except for the mesh portion 215) may be closed. Moreover, in FIG. 1, the heat exchange part 23 may be provided with two or more. In this case, the plurality of heat exchange units 23 may be provided so as to surround the fluid blowing pipe 24 in a plan view. Alternatively, a plurality of fluid blowing pipes 24 may be provided.

  When a further underground aquifer exists between the lower aquifer 13 and the upper aquifer 15, the mesh part 215 may also be provided at a position corresponding to the underground aquifer. On the contrary, when the upper aquifer 15 does not exist, the mesh part 215 may be provided only in the lower end part 213 corresponding to the lower aquifer 13, as shown in FIG.

  The configuration (shape / structure) of the heat exchange section 23 and the fluid blowing pipe 24 is not limited to the specific examples shown in the above-described embodiment. For example, the heat exchange part 23 is not limited to a U-shaped tube. Further, the fluid blowing pipe 24 may be a U-shaped tube similar to the heat exchanging portion 23 of FIG. In this case, the fluid ejection opening 243 may be provided in the bent portion and the vicinity thereof.

  As shown in FIG. 2, a fluid blowing portion 244 may be provided at the lower end of the fluid blowing tube 24 so as to extend laterally. In this case, the fluid blowing portion 244 is formed in, for example, a tubular shape or a disc shape (a columnar shape having a very small height with respect to the diameter), and extends from the lower end of the heat exchange portion 23 toward the lower end. And may be configured to eject air upward.

  By the way, the temperature of the air blown into the groundwater 17 gradually changes toward the temperature of the groundwater 17 while rising in the groundwater 17 (even when it is near the outside temperature at the beginning of being ejected from the fluid ejection opening 243). To do. Then, the air whose temperature has changed closer to the groundwater 17 stays in the upper space 19 thereafter. Then, the temperature of the air staying in the upper space 19 is, during the operation of the underground heat exchanger 20, the outside air temperature, the temperature of the groundwater 17 in the vicinity of the underground aquifer (lower aquifer 13), Between.

  In this regard, as shown in FIG. 2, the gas discharge pipe 261 is connected to the fluid pumping means 25 so as to stay in the upper space 19 (the temperature is closer to the temperature of the groundwater 17 than the outside air temperature). ) The air is refluxed (delivered) to the fluid pumping means 25. The air recirculated from the upper space 19 to the fluid pumping means 25 in this manner is sent to the fluid blowing pipe 24 by the fluid pumping means 25. That is, in such a configuration, a part of the air ejected from the fluid ejection opening 243 is circulated between the upper space 19 and the fluid pressure feeding means 25.

  In this way, by returning the air in the upper space 19 to the fluid pumping means 25, the temperature of the air in the upper space 19 is changed to the underground aquifer (lower zone) during operation of the underground heat exchanger 20. It approaches the temperature of the groundwater 17 in the vicinity of the water layer 13). Then, the temperature of the air sent to the fluid blowing pipe 24 by the fluid pumping means 25 and ejected from the fluid ejection opening 243 also approaches the temperature of the groundwater 17 in the vicinity of the underground aquifer (lower aquifer 13). Therefore, according to such a configuration, a part of the heat to be exchanged between the groundwater 17 and the heat medium H is favorably suppressed from being consumed for heat exchange between the heat medium H and the gas (bubbles). Therefore, the heat exchange efficiency is further improved. In such a configuration, the pressure regulating valve 262 is not provided unless a negative pressure that causes an excessive rise in the water level 18 in the upper space 19 (a rise such that groundwater 17 overflows to the surface 12 side) is generated. May be omitted as appropriate.

  Instead of the gas exhaust pipe 261 shown in FIG. 1, an exhaust through hole 265 that is a through hole provided in the lid 22 may be used as shown in FIG. 3. The vent hole 265 is formed so that the upper space 19 and the outside (outside air on the ground surface 12 side) can communicate with each other. In this case, as shown in FIG. 3, a pressure regulating valve 266 for opening and closing the vent hole 265 according to the pressure of the gas in the upper space 19 may be attached to the lid body 22.

  Alternatively, the pressure regulating valve 266 in FIG. 3 may be omitted depending on device specifications such as the maximum output of the fluid pressure feeding means 25 (see FIG. 4). In this case, as shown in FIG. 4, a plurality of vent holes 265 may be provided. Alternatively, in this case, a gas passage (gap) formed at a joint portion between the lid body 22 and the upper end opening 211 in the casing 21 may be used instead of the ventilation through hole 265.

  A pressure sensor for measuring the pressure of the gas in the upper space 19 may be provided. This pressure sensor can be attached to the lid 22, for example. In such a configuration, various operations for adjusting the pressure of the gas in the upper space 19 (the driving state of the fluid pumping means 25 and the like) can be controlled by the control unit 27 based on the output of the pressure sensor. . Specifically, for example, when the pressure of the gas in the upper space 19 reaches a predetermined value, the driving of the fluid pumping means 25 can be stopped. As the predetermined value, for example, an intermediate value between the valve opening pressure of the pressure regulating valve 262 and the valve opening pressure of the safety valve 264 can be used. Alternatively, the pressure regulating valve 262 may be an electromagnetic valve whose opening / closing is controlled by the control unit 27.

  The “fluid” in the present invention is not limited to (compressed) air. That is, for example, an inert gas such as nitrogen gas or argon gas can be used. Alternatively, for example, a liquid such as water or silicone oil can be used. When an inert gas or liquid is used, oxidation of each part (pipe parts such as the heat exchanging part 23, ground water 17, soil, etc.) can be prevented or suppressed satisfactorily. When a fluid other than air is used, as shown in FIG. 5, a fluid supply source 280 such as a gas cylinder or a gas generator for supplying the fluid is connected to the fluid pumping means 25. Is done.

  In addition, when the fluid can be recovered, a fluid recirculation unit 281 for recovering the fluid from the upper space 19 and returning it to the fluid pumping means 25 can be provided as shown in FIG. The fluid return part 281 includes at least a pipe. This piping may be appropriately provided with a pressure feeding means such as a pump, a valve, or the like. Thereby, the consumption of the said fluid is suppressed favorably by reusing the said fluid, obtaining the same favorable thermal efficiency as the above-mentioned.

  In FIG. 6, assuming that the fluid stays at the bottom of the upper space 19 because the specific gravity of the fluid is greater than that of air (see the two-dot chain line in the figure), the fluid reflux unit 281 Although the state connected to the bottom in the upper space 19 is illustrated, the present invention is not limited to this. That is, when the fluid is a gas having a specific gravity smaller than that of air, the fluid recirculation unit 281 can be connected to the upper portion of the upper space 19. In this case, the gas exhaust pipe 261 and the like shown in FIG. 2 can be used in place of the fluid recirculation part 281 shown in FIG.

  DESCRIPTION OF SYMBOLS 10 ... Ground, 11 ... Vertical hole, 12 ... Ground surface, 13 ... Lower aquifer, 15 ... Upper aquifer, 17 ... Groundwater, 19 ... Upper space, 20 ... Underground heat exchanger, 21 ... Casing, 22 ... Cover Body 23... Heat exchanging section 24 fluid inlet pipe 25 fluid pressure feeding means 26 pressure adjusting means 211 upper end opening 213 lower end 215 mesh part 216 mesh opening 241 Blow pipe lower end portion, 243 ... fluid ejection opening, 244 ... fluid blow section, 261 ... gas discharge pipe, 262 ... pressure regulating valve, C ... central axis, H ... heat medium.

Claims (3)

It is a cylindrical member embedded in a vertical hole excavated in the ground, and is formed so that the upper end on the surface side is open, and a mesh part through which groundwater as a heat source can pass is at least in the underground aquifer A casing provided at the corresponding lower end,
A lid attached to the opening so as to close the opening at the upper end of the casing;
It is accommodated in the space inside the casing so as to reach the depth of the mesh portion provided at the lower end portion of the casing while penetrating the lid body, and the outer surface is in contact with the groundwater and the inside A heat exchange part, which is a tubular member configured to exchange heat between the groundwater in the space and the heat medium by flowing while the heat medium is stored in a liquid-tight manner,
A tubular member that penetrates the lid and is accommodated in the space inside the casing so as to reach the depth of the bottom of the heat exchange unit, and is a fluid in the vicinity of the bottom of the heat exchange unit. A fluid blowing pipe having a fluid ejection opening formed to blow the fluid into the groundwater in the space by ejecting
Fluid pumping means connected to the fluid blowing pipe at the end opposite to the fluid ejection opening so as to deliver the fluid to the fluid blowing pipe;
Pressure adjusting means provided to adjust the pressure of the gas in the space inside the casing;
Fluid recirculation means provided to recirculate the fluid from the space inside the casing to the fluid pumping means;
With
The pressure adjusting means is
A gas exhaust pipe provided so as to be able to communicate with the outside below the lid body and above the water level in the space inside the casing by penetrating the lid body;
A pressure regulating valve attached to the gas discharge pipe;
An underground heat exchanger characterized by comprising: The underground heat exchanger according to claim 1,
The underground heat exchanger, wherein the mesh part is also provided above the lower end part of the casing. The underground heat exchanger according to claim 1 or 2 ,
The underground heat exchanger, wherein the heat exchange part is a U-shaped tube having a longitudinal direction along the axial direction of the casing.

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