JP5779206B2 - Underground heat exchanger - Google Patents

Description

  The present invention relates to a geothermal heat exchange device that exchanges heat generated by a use-side heat source and geothermal heat via a predetermined heat medium, and more specifically, more heat exchange using groundwater. The present invention relates to a geothermal heat exchange device with improved efficiency.

  Geothermal heat can be used in a heat exchange tube that circulates the heat medium embedded in a heat exchange well installed in the ground to exchange heat, or to use groundwater for heat exchange. In recent years, hybrid ground heat exchangers that combine both types have been proposed.

  That is, as described in Patent Document 1, for example, in a hybrid type underground heat exchanger, a slit or the like is formed in a part of a casing inserted along a heat exchange well formed in the ground from the ground surface. By performing the water permeation treatment, groundwater flows in the casing (steel pipe), and a heat exchange tube is inserted therein to exchange heat with the groundwater.

  According to this, since groundwater of constant temperature always flows in the casing, stable heat exchange is performed between the heat exchange tube and the groundwater.

  However, the following problems remain in this hybrid type underground heat exchanger. That is, in the conventional hybrid type, since the space between the groundwater level surface inside the casing and the ground surface is hollow (that is, the air layer having the lowest thermal conductivity), almost no heat exchange is performed between them.

  In addition, in the conventional heat exchange tube, one heat exchange tube is bent into a U shape, and the bundled U tube is inserted into the casing for heat exchange. However, the U tube is bundled. The forward path side and the return path side are likely to come into contact with each other, and the heat exchange efficiency at that portion is lowered. As a result, the heat exchange efficiency of the entire apparatus may be lowered.

JP 2008-292030 A

  Then, the subject of this invention is providing the underground heat heat exchange apparatus which raised the heat exchange efficiency with the groundwater of the heat exchange tube arrange | positioned in the casing.

To solve the problems described above, the present invention includes a heat generated in the use side heat source, in the underground heat heat exchanger device for heat exchange through a predetermined heat medium and geothermal heat, the ground from the ground surface A heat exchanging well drilled toward the aquifer, a cylindrical casing inserted along the heat exchanging well, and a heat exchanging tube through which the heat medium flows, and the heat in the casing exchange tube is disposed over the bottom of the heat exchanger well from the ground surface, in the casing, together with permeability hole for passing a part of the groundwater of the aquifer in the in the casing is applied The upper part of the casing above the groundwater level line is filled with a filler via a partition plate .

Preferably, the heat exchange tube is provided with a spacer for holding the heat exchange tubes at a predetermined interval.

Also, preferably, the upper Symbol filler, concrete, either mortar or soil is used.

According to the present invention , by filling the upper portion of the casing with the filler, it is possible to promote heat exchange on the upper side of the casing where no groundwater exists, and to increase the heat exchange efficiency of the entire system. In addition, since the forward path side and the backward path side of the heat exchange tube are supported at a predetermined interval via the spacer, it is possible to always ensure a constant heat exchange efficiency.

1 is an overall view of a geothermal heat exchange device according to an embodiment of the present invention. The partial expanded sectional view which expanded the upper part side of the casing of the said underground heat exchanger. The partial cross-sectional view of the said underground heat heat exchange apparatus. (A), (b) The schematic diagram which shows the shape of the slit of the said casing. The perspective view of a spacer.

  Next, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

  As shown in FIG. 1, the underground heat exchanger 1 includes a plurality of underground heat exchangers 1 a to 1 i. The local heat heat exchangers 1a to 1i are excavated almost vertically from the ground surface G toward the ground. In this example, the heat heat exchangers 1a to 1i are arranged at nine positions with a predetermined interval. In addition, the basic structure of the heat heat exchangers 1a to 1i in each place is the same.

  The heat heat exchangers 1a to 1i in each location include a heat exchange well 2 excavated vertically from the ground surface G toward the ground, a casing 3 inserted along the heat exchange well 2, and an inside of the casing 3 And a heat exchange tube 4 to be inserted.

  Among the local heat exchangers 1a to 1i, the heat exchange well 2a (hereinafter, the first heat exchange well 2a) of the underground heat exchanger 1a is more impermeable than the underground aquifer A. Drilled to a depth up to the formation.

  That is, the first heat exchanging well 2a is a heat exchanging well for test excavation that is excavated first, grasping the exact position of the aquifer A, and the underground heat heat exchanger 1b to be excavated thereafter. From the aquifer A to be used for the TRT / TCP test (Thermal Response Test / Thermal Conductivity Test) for measuring the excavation depth of each heat exchange well 1i, the temperature change in the aquifer A, the flow velocity of groundwater, etc. It is formed so as to be deep (position reaching the impermeable layer B).

  A dedicated casing 3a is inserted into the first heat / heat exchange well 2a for use in the TRT / TCP test described above. The casing 3a is made of a steel pipe having a length from the ground surface G to the bottom, and a large number of slits 31 as a water permeation treatment are provided on the surface.

  In this example, as shown in FIG. 4A, the slit 31 is formed by arranging parallel slits in a zigzag manner along the axial direction of the casing 3a, and covers almost the entire area from the lower end side to the upper end side of the casing. Is formed.

  In addition, as shown in FIG.4 (b), it may replace with the slit 31 and the round hole 31b may be sufficient, and a square hole etc. may be sufficient. Furthermore, the arrangement may be arbitrarily selected according to use, such as a staggered pattern or a lattice pattern.

  According to this, since the slit 31 is provided over the entire circumference of the casing 3a, when the casing 3a is embedded along the heat exchange well 2a, groundwater passes through the slit 31 to the inside of the casing 3a. Flowing.

  At that time, by arranging temperature sensors at regular intervals from the upper end to the bottom of the casing 3a and measuring the temperature distribution change by the TRT / TCP test, the exact range of the aquifer A and the aquifer A It is possible to measure how groundwater is flowing, and as a result, it is possible to determine a position where heat exchange is more effective.

  Based on this measurement data, the casing 3 after the second heat exchange well 2b is formed so that its length is from the ground surface G to almost the lower end of the aquifer A, and further to the aquifer A. By providing the slit 31 at the corresponding optimum position, the construction cost of the casing 3 can be suppressed.

  As a more preferable aspect, by increasing the number and area of slits at a position where groundwater actively flows, an operation with further improved heat exchange efficiency is possible.

  An upper side of the casing 3 (a position above the groundwater level line WL) is filled with a filler (grout) 32. Referring also to FIG. 2, on the upper side of the casing 3, a lid member (packer) 33 for filling the filler 32 and a stopper 34 for pressing the lid member 33 are provided.

  The stopper 34 has a flange shape formed along the inner peripheral surface of the casing 3 and is integrally fixed to the inner peripheral surface of the casing 3 by, for example, welding. In this example, the stopper is formed in a ring shape, but may have a shape other than this, and it is sufficient that at least the cover member 33 can be prevented from falling off.

  The lid member 33 is made of, for example, a steel plate or a grating, and includes an insertion portion 331 through which a heat exchange tube 4 described later is inserted. The material of the lid member 33 only needs to have at least a shape that prevents the filler 32 from falling down.

Filler 3 2 consists those filled concrete or mortar, such as surplus soil at the time of drilling heat exchange wells 2 is provided so as to be in close contact along the heat exchange tubes 4. Further, the filling material 3 2 to have a water permeability, may be increased more heat exchange efficiency imbued water filler 3 2.

According to this, by satisfying the upper side of the casing 3 with a filler 3 2, it is possible to promote heat exchanging heat exchange tubes 4 arranged above the groundwater level line WL, and enhance the heat exchange efficiency be able to.

  Further, as shown in FIG. 3, a sediment prevention sheet 35 is provided on the inner peripheral surface of the casing 3 to prevent sediment from flowing into the casing 3 through the slit 31. The earth and sand prevention sheet 35 is made of a sheet having water permeability, and is bonded together so as to be in close contact with the inner peripheral surface of the casing 3.

  In this example, the earth and sand prevention sheet 35 is bonded to the inner peripheral surface of the casing 3, but may be bonded along the outer peripheral surface of the casing 3.

Next, as the heat exchange tube 4 , a U-shaped tube is used in which a straight tube is bent into a U-shape, one side being the forward path side and the other being the return path side. Inserted. In this example, the heat exchange tube 4 includes one heat exchange tube 4 for one heat exchange well 2. For example, two U-shaped heat exchange tubes 4 are crossed in an X shape. May be inserted.

  Both the inlet side and the outlet side of the heat exchange tube 4 are connected to a heat exchange device (not shown). In the present invention, the heat exchange device is not particularly limited, but as a typical example, a hot water supply using a heat cycle, an air conditioner, or the like is used as the use side heat source.

  The heat exchange tube 4 of the present invention is provided with a spacer 5 for supporting the forward path side and the return path side of the heat exchange tube 4 at a predetermined interval. 3 and 5, the spacer 5 has a flat base 51 and is formed in a spanner shape having U-shaped clip portions 52, 52 at both ends thereof. In this example, a plurality of spacers 5 are provided at predetermined intervals along the length direction of the heat exchange tube 5.

  Each clip part 52, 52 is formed in a semicircular shape so as to match the outer diameter of the heat exchange tube 4, and the heat exchange tube 4 is fitted therein. In this example, each of the clip portions 52, 52 has a C-shaped tip, but the shape is arbitrarily selected according to the specifications as long as the heat exchange tube 4 can be held. Good.

  In this embodiment, the spacer 5 is used when one U-shaped heat exchange tube 4 is disposed. For example, a cross-shaped base 51 is provided, and clip portions 52 are provided at four positions at each end. It can be used also for the X-shaped heat exchange tube 4 described above.

  According to this, since the forward path side and the return path side of the heat exchange tube 4 are supported by the spacer 5 at a predetermined interval, the heat exchange efficiency between the heat exchange tube 4 and the groundwater can be always constant, As a result, the heat exchange efficiency of the entire system can be increased.

1a-1i Underground heat exchanger 2 (2a-2i) Heat exchange well 3 (3a-3i) Casing 31 Slit 32 Filler (grout)
33 Lid member (packer)
4 Heat exchange tube 5 Spacer A Aquifer WL Groundwater level surface

Claims (3)

In the underground heat heat exchange device for exchanging heat generated by the use side heat source and underground heat through a predetermined heat medium,
A heat exchange wells to be drilled from the ground surface toward the aquifer in the ground, a cylindrical casing which is inserted along the heat exchanger well, a heat exchange tube in which the heating medium flows, the The heat exchange tube is disposed in the casing from the ground surface to the bottom of the heat exchange well, and the casing has a water permeable hole for allowing a part of groundwater in the aquifer to flow into the casing. A geothermal heat exchange device characterized in that the upper side of the casing above the groundwater level line is filled with a filler via a partition plate . The underground heat heat exchanger according to claim 1, wherein the heat exchange tube is provided with a spacer for holding the heat exchange tubes at a predetermined interval . The ground heat heat exchanger according to claim 1 or 2, wherein any one of concrete, mortar, and soil is used as the filler.

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