Geothermal Utilization Device

Abstract

To provide an environmentally-friendly underground heat utilization device.SOLUTION: An underground heat utilization device comprises a cylindrical casing and a stirring device. The cylindrical casing is buried in the ground, and has an upper cylindrical part and a lower cylindrical part. Between the upper cylindrical part and the lower cylindrical part, a partition wall is provided to separate the upper and lower cylindrical parts. The upper cylindrical part has heat transfer fluid inside. The lower cylindrical part has a water hole for groundwater. Either or both of the upper cylindrical part and the lower cylindrical part have the stirring device.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a geothermal heat utilization apparatus that utilizes underground heat as a heat source (including a high-temperature heat source and a low-temperature heat source) for snow melting, air conditioners, refrigerators, and the like.

Background Art

[0002] Conventionally, as disclosed in Patent Document 1, there has been a groundwater circulation apparatus that pumps up groundwater used as a heat source (including a high-temperature heat source and a low-temperature heat source) for snow melting, air conditioners, refrigerators, and the like, and circulates the groundwater between the groundwater vein and the ground surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] Since the pumped-up groundwater is returned to the groundwater vein after being used by ground facilities, there are concerns about adverse environmental impacts, and there are cases where the operation is subject to regulations by local governments and the like. The present invention aims to provide an environmentally friendly geothermal heat utilization apparatus.

Means for Solving the Problem

[0005] In view of such problems, a first aspect of the present invention has the following configuration. A tubular casing and an agitation device are provided, the tubular casing is buried underground, and has an upper tubular portion and a lower tubular portion, a partition wall is provided between the upper tubular portion and the lower tubular portion to separate the upper and lower sides, The upper cylinder contains a heat transfer fluid, and the lower cylinder has a groundwater passage. The partition wall separates the upper and lower cylinders and functions as a heat exchange section from the groundwater in the lower cylinder to the heat transfer fluid in the upper cylinder. This allows for heat exchange from the groundwater in the lower cylinder to the heat transfer fluid in the upper cylinder without pumping up the groundwater. The stirring device is Upper cylinder part and Lower cylinder part Both to Each is provided and attached to a single drive shaft. A geothermal energy utilization device characterized by...

[0006] Also, In another form A geothermal energy utilization device characterized by comprising a cylindrical casing and a stirring device, the cylindrical casing being buried underground, having an upper cylindrical section and a lower cylindrical section, a partition wall separating the upper and lower cylindrical sections, the upper cylindrical section containing a heat transfer fluid, the lower cylindrical section having a groundwater passage hole, and having a stirring device in either the upper cylindrical section or the lower cylindrical section or both. Disclose . [Effects of the Invention]

[0007] It has become possible to use groundwater as a source of heat and cold without having to pump it up. [Brief explanation of the drawing]

[0008] [Figure 1] An explanatory diagram of the first embodiment. [Figure 2] Diagram illustrating a conventional geothermal energy utilization system. [Figure 3] This is an explanatory diagram of the second embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals in different figures indicate parts with the same function, and redundant explanations in each figure will be omitted as appropriate. [Examples]

[0010] (First aspect) Figure 1 is an explanatory diagram of the first embodiment. The ground into which the cylindrical casing 1 of the geothermal energy utilization device 8 is buried contains an impermeable layer and an aquifer. The aquifer is a water-containing geological layer formed between the upper and lower impermeable layers. For example, it is composed of porous, permeable, unconsolidated geological layers such as sand layers and gravel layers, or fractured sandstone, conglomerate, rarely basalt, igneous rock layers consisting of scattered lava, or porous, cavities in limestone layers. Multiple aquifers may exist, separated by impermeable layers. The cylindrical casing 1 is buried so as to reach the aquifer with abundant water. It is preferable.

[0011] (Cylindrical casing) The cylindrical casing 1 of the first embodiment is configured as a double cylinder, comprising an inner cylinder portion 12 and an outer cylinder portion 11 that surrounds the inner cylinder portion 12 at a predetermined distance. The bottom of the inner cylinder 122 is closed, and the inner cylinder 12 and the outer cylinder 11 are not in any communication. The heat transfer fluid B is stored inside the inner cylinder 12. The outer cylinder portion 11 has numerous water passage holes 111 on its outer circumferential surface, allowing groundwater W to flow into the outer cylinder portion 11. The water passage holes 111 are so-called strainers. Because the inner cylinder portion 12 is inserted into the outer cylinder portion 11 at a predetermined distance, a gap is created between the outer circumferential surface of the inner cylinder portion 12 and the inner circumferential surface of the outer cylinder portion 11. Groundwater W that has flowed into the outer cylinder 11 through the water passage holes 111 accumulates in the gap. Since there are no points of communication between the inner cylinder 12 and the outer cylinder 11, the heat transfer fluid B stored in the inner cylinder 12 does not flow into the outer cylinder 11, and the groundwater W inside the outer cylinder 11 is not contaminated.

[0012] The top of the cylindrical casing 1 is above ground. A lid 13 is placed over the top of the inner cylinder 12 to prevent debris from entering the inside of the inner cylinder 12.

[0013] (heat transfer fluid) The heat medium fluid B is preferably an antifreeze liquid (brine) so as not to freeze inside the heat medium flow path 41 in winter, and is mainly composed of an antifreeze liquid such as ethylene glycol, for example. In order to give more consideration to the impact on the environment, it is also possible to use water as the heat medium fluid B.

[0014] (Drive shaft) The drive shaft 2 rotates by receiving power from a motor M placed outside the cylindrical casing 1. The drive shaft 2 is supported by a thrust bearing 22 attached to the lid 13 and a thrust bearing 22 attached to the inner cylinder bottom portion 122. The drive shaft 2 penetrates the inner cylinder bottom portion 122 and reaches the outer cylinder portion 11. The thrust bearing 22 at the inner cylinder bottom portion 122 allows the drive shaft 2 to rotate freely while maintaining watertightness.

[0015] (Heat medium flow path) The inner cylinder portion 12 is provided with a heat medium flow path 41 that sends the heat medium fluid B out of the cylindrical casing 1 and returns it to the inner cylinder portion 12 again. In the first embodiment, there are two systems of the heat medium flow path 41, one of which is the heat medium flow path 41 that sends the heat medium fluid B to the parking lot X1, and the other is the heat medium flow path 41 that sends the heat medium fluid B to the facility X2. In both paths, the heat medium fluid B is sucked up by the pump P from the suction port 41a. Then, the heat (warm heat or cold heat) of the heat medium fluid B is subjected to heat exchange, and is returned from the discharge port 41b to the inner cylinder portion 12 again. The heat medium flow path 41 leading to the parking lot X1 is mainly for melting snow and is used in winter. The heat medium flow path 41 leading to the facility X2 is used in both summer and winter. In summer, the heat medium fluid B is used as a cold heat source, is subjected to heat exchange by the heat pump HP, and is used for air conditioning and coolers. In addition, in winter, the heat medium fluid B is used as a warm heat source, is subjected to heat exchange by the heat pump HP, and is used for hot water production, heaters and the like.

[0016] (Heat exchange between groundwater and heat medium fluid) Groundwater W is stored in the outer cylinder portion 11, and the groundwater W exchanges heat with the heat transfer fluid B separated by the inner cylinder portion 12. This heat exchange allows the heat of the groundwater W to be utilized without pumping it up. The heat exchange occurs in the region where the inner cylinder portion 12 and the groundwater W are in contact. The material of the inner cylinder portion 12 is preferably a metal with good thermal conductivity, and it is preferable to attach members such as aluminum fins to the inside and outside of the inner cylinder portion 12 to increase the contact area with the groundwater W and the heat transfer fluid B in order to promote heat exchange.

[0017] (Agitation device in the inner cylinder) In the first embodiment, the propeller (agitation device) 31 is attached to a single drive shaft 2 at two locations inside the inner cylinder 12 and at one location inside the outer cylinder 11. The drive shaft 2 is rotated by a motor M, which rotates the propeller (agitation device) 31 and agitates the heat transfer fluid B and groundwater W.

[0018] The heat transfer fluid B is drawn up by the pump P from the inlet 41a provided in the inner cylinder 12 via the heat transfer fluid channel 41, undergoes heat exchange outside the cylindrical casing 1, and is returned to the inner cylinder 12 again from the outlet 41b. Due to this circulation of the heat transfer fluid B, the temperature of the heat transfer fluid B inside the inner cylinder 12 becomes uneven, impairing the efficiency of heat exchange with the groundwater W in the outer cylinder 11. The propeller (agitator) 31 works to eliminate this temperature unevenness and improve the heat exchange efficiency.

[0019] (Agitation device in the outer cylinder) In the first embodiment, the drive shaft 2 penetrates the bottom 122 of the inner cylinder and reaches the outer cylinder 11. The propeller (agitation device) 31 is attached to the drive shaft 2 that protrudes into the outer cylinder 11 and agitates the groundwater W inside the outer cylinder 11. Fresh groundwater W is constantly flowing into the interior of the outer cylinder 11 through water passage holes 111 that are evenly distributed in the lower region of the outer cylinder 11. The groundwater W inside the outer cylinder 11 is heated or cooled by the heat (cold or warm) of the heat transfer fluid B inside the inner cylinder 12, resulting in temperature variations. The propeller (agitation device) 31 agitates the groundwater W inside the outer cylinder 11, thereby eliminating temperature variations and promoting the inflow of fresh groundwater W.

[0020] To promote the inflow of fresher groundwater W, it is preferable to employ a Bernoulli flow agitator or an agitator 3 having centrifugal blades. Because these agitators 3 have a strong horizontal fluid discharge effect, they can direct the flow of groundwater W towards the water passage holes 111 provided around the outer cylinder 11. Through this action, these agitators 3 can promote the exchange of groundwater W.

[0021] Figure 2 is an explanatory diagram of a conventional geothermal energy utilization device 8. In the conventional geothermal energy utilization device 8, groundwater W is drawn up from the groundwater intake port 51a and sent via the groundwater channel 51 to the heat exchanger of the heat pump HP in the facility X2. After heat exchange through the heat pump HP, the groundwater W passes through the groundwater channel 51 again and returns to the outer cylinder 11 from the groundwater outlet port 51b. In the conventional geothermal energy utilization device 8, the groundwater W in the outer cylinder 11 was not stirred using the stirring device 3. The reason will be explained.

[0022] The outer cylinder 11 has water passage holes 111 in its wall, allowing pebbles and sand to flow into the outer cylinder 11 from the aquifer. The stirring device 3 stirs up the pebbles and sand. The stirred-up pebbles and sand are sucked in through the groundwater intake port 51a, clogging the heat exchanger of the heat pump HP and causing problems. Removing the foreign matter from the heat exchanger is extremely difficult, and in the worst case, the entire heat exchanger may need to be replaced. In the conventional geothermal energy utilization device 8, temperature variations in the groundwater W inside the outer cylinder 11 occurred, similar to the first embodiment of the geothermal energy utilization device 8, but this problem could not be prevented, and the stirring device 3 could not be used.

[0023] In the first embodiment of the present invention, groundwater W is not sent to the heat pump HP, making it environmentally friendly. Furthermore, because the groundwater W can be stirred, the first embodiment has significantly improved heat utilization efficiency compared to the conventional geothermal energy utilization device 8.

[0024] (Types of stirring devices) The agitator 3 is not limited to a propeller 31. For example, using a Bernoulli flow agitator that generates liquid flow by pressure difference due to centrifugal force has the following advantages: A Bernoulli flow agitator draws fluid up from above and below and discharges the fluid horizontally. Because a Bernoulli flow agitator agitates the fluid in both the vertical and horizontal directions, it can perform highly efficient agitation. Furthermore, an agitator 3 equipped with centrifugal blades is similar to a Bernoulli flow agitator, drawing in fluid from the axial direction (vertical direction) and discharging the fluid horizontally, and can be expected to perform similar functions to a Bernoulli flow agitator.

[0025] In this invention, the drive shaft 2 is not essential. A stirring device 3 that does not use a drive shaft 2, such as an air pump, may also be used. Furthermore, if a watertight stirring device 3 is used and power is supplied directly via a power cable, the drive shaft 2 and motor M become unnecessary. The stirring device 3 only needs to be able to stir the fluid; for example, it could be a pump that generates a water flow. The type of stirring device 3 is appropriate. Various power supply methods can be employed for the stirring device 3, including mechanical supply methods such as a drive shaft 2, direct power supply via a power cable, air supply, and a method that supplies only water flow using an externally installed pump. The selection of the method can be made appropriately according to the purpose, such as cost-effectiveness and ease of maintenance.

[0026] (Second aspect) The first embodiment is particularly effective when the groundwater level is high and the outer cylindrical portion 11 is filled with groundwater W up to the top. The second embodiment is effective when the groundwater level is low and the groundwater level remains near the bottom of the outer cylindrical portion 11. Figure 3 is an explanatory diagram of the second embodiment, in which the cylindrical casing 1 is divided into an upper cylindrical portion 14 and a lower cylindrical portion 15 by a partition wall 16.

[0027] The upper cylindrical section 14 stores a heat transfer fluid B inside. The lower cylindrical section 15 has numerous water passage holes 111 on its outer circumference and is filled with groundwater W flowing in from the aquifer. The partition wall 16 separates the upper cylindrical section 14 and the lower cylindrical section 15 and functions as a heat exchange section from the groundwater W in the lower cylindrical section 15 to the heat transfer fluid B in the upper cylindrical section 14. For this reason, it is preferable that the partition wall 16 be made of a material with high thermal conductivity, such as aluminum. Furthermore, to improve heat transfer, it is preferable to provide fins on the surface of the partition wall 16 to increase its surface area.

[0028] The second embodiment, like the first embodiment, is a method of utilizing heat by exchanging heat from groundwater W to a heat transfer fluid B without pumping up groundwater W. The present invention does not violate regulations on pumping up groundwater W and is environmentally friendly.

[0029] The inner cylinder portion 12 and outer cylinder portion 11 of the first embodiment correspond to the upper cylinder portion 14 and lower cylinder portion 15 of the second embodiment, respectively, and the type and operation of the stirring device 3 are common to both the first and second embodiments. .

[0030] Furthermore, both the first and second embodiments share the common feature of having a section for storing the heat transfer fluid B and a section located in the aquifer for storing groundwater W. In the first embodiment, the stirring device 3 may be provided in either the outer cylinder 11 or the inner cylinder 12, or both. In the second embodiment, the stirring device 3 may be provided in either the upper cylinder 14 or the lower cylinder 15, or both. The stirring device 3 can contribute to improving thermal efficiency even if it is present in only one of them, and it is even preferable if it is present in both.

[0031] While embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and any design changes, etc., that do not depart from the spirit of the present invention are also included. Furthermore, the aforementioned implementation methods can be combined by reusing each other's technologies, as long as there are no particular contradictions or problems in their purpose, structure, etc. [Explanation of Symbols]

[0032] 1. Cylindrical casing 11 Outer cylinder 111 Water passage hole 12 Inner cylinder 122 Inner cylinder bottom 13 Lid 14 Upper cylinder part 15 Lower cylinder part 16 Partition Wall 2 drive shafts 22 thrust bearings 3. Stirring device 31. Propeller (Agitator) 41 Heat transfer fluid channel 41a Inlet 41b Outlet 51 Groundwater flow path 51a Groundwater inlet 51b Groundwater outlet 8 Geothermal heat utilization equipment B Heat transfer fluid HP Heat Pump M Motor P Pump W Groundwater X1 Parking X2 Facility

Claims

[Claim 1] Equipped with a cylindrical casing and a stirring device, The cylindrical casing is buried underground and has an upper cylindrical section and a lower cylindrical section. There is a partition wall between the upper and lower cylindrical sections, separating them. The upper cylindrical section contains a heat transfer fluid inside. The lower section is equipped with a hole for groundwater to pass through. The partition wall separates the upper and lower cylindrical sections and functions as a heat exchange section from the groundwater in the lower cylindrical section to the heat transfer fluid in the upper cylindrical section. It utilizes heat by exchanging heat from the groundwater in the lower cylindrical section to the heat transfer fluid in the upper cylindrical section without pumping up the groundwater. A geothermal energy utilization device characterized in that the stirring devices are provided in both the upper and lower cylindrical sections and are attached to a single drive shaft.

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