Underground heat 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 energy utilization device that utilizes underground heat as a heat source (including a hot heat source and a cold heat source) for melting snow, or for use in an air conditioner, a refrigerator, or the like. [Background technology]

[0002] Conventionally, there has been a groundwater circulation device, as described in Patent Document 1, that pumps up groundwater used as a heat source (including hot and cold heat sources) for snow melting, air conditioners, freezers, etc., and circulates it between the groundwater vein and the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-228928 Summary of the Invention [Problem to be solved by the invention]

[0004] Because the pumped groundwater is used in aboveground facilities and then returned to the underground aquifer, there are concerns about its adverse impact on the environment, and it has been subject to regulations by local governments, etc. An object of the present invention is to provide an environmentally friendly geothermal energy utilization device. [Means for solving the problem]

[0005] In view of the above problems, a first aspect of the present invention has the following configuration. A geothermal energy utilization device comprising: a cylindrical casing and a stirring device, the cylindrical casing being buried in the ground, having an outer tube portion and an inner tube portion, the outer tube portion having a groundwater passage hole, the inner tube portion having a bottom portion which is closed and a heat transfer fluid is placed inside, and a stirring device being provided in either or both of the outer tube portion and the inner tube portion.

[0006] In addition, a second aspect of the present invention solves the problem by providing a geothermal energy utilization device comprising a cylindrical casing and a stirring device, the cylindrical casing being buried in the ground and having an upper tube portion and a lower tube portion with a partition wall between the upper and lower tube portions to separate the upper and lower portions, the upper tube portion containing a heat transfer fluid, the lower tube portion having a groundwater passage hole, and either or both of the upper and lower tube portions having a stirring device. Effect of the Invention

[0007] It is now possible to use groundwater as a source of heating and cooling without pumping it up. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram of a first embodiment. [Diagram 2] FIG. 1 is an explanatory diagram of a conventional geothermal energy utilization device. [Diagram 3] FIG. 2 is an explanatory diagram of a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same reference numerals in different drawings indicate parts having the same function, and duplicated descriptions in each drawing will be omitted as appropriate. EXAMPLES

[0010] (First aspect) FIG. 1 is an explanatory diagram of the first embodiment. The ground in 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 stratum formed between upper and lower impermeable layers. For example, it is composed of porous and permeable unconsolidated stratum such as a sand layer or a gravel layer, or a layer of igneous rock consisting of overlapping sandstone, conglomerate, and occasionally basalt and dispersed lava with cracks, or a layer of limestone with porous spaces and cavities. There may be multiple layers of aquifers with impermeable layers between them. The cylindrical casing 1 is buried so that it can reach the aquifer with an abundant amount of water. It is preferred.

[0011] (Cylindrical casing) The cylindrical casing 1 of the first embodiment is configured in a double cylindrical shape including an inner cylindrical portion 12 and an outer cylindrical portion 11 surrounding the inner cylindrical portion 12 at a predetermined distance. The inner cylinder bottom 122 is closed, and there is no communication between the inner cylinder 12 and the outer cylinder 11. The heat transfer fluid B is stored in the inner cylinder 12. The outer cylinder portion 11 has many water holes 111 on the outer cylinder circumferential surface, so that groundwater W flows into the outer cylinder portion 11. The water holes 111 are so-called strainers. Since the inner cylinder portion 12 is inserted into the outer cylinder portion 11 at a predetermined distance, a gap is formed between the outer peripheral surface of the inner cylinder portion 12 and the inner peripheral surface of the outer cylinder portion 11. Groundwater W that flows into the outer cylinder portion 11 through the water passage hole 111 accumulates in the gap. Since there is no communication between the inner cylinder portion 12 and the outer cylinder portion 11, the heat transfer fluid B stored in the inner cylinder portion 12 does not flow into the outer cylinder portion 11, and the groundwater W in the outer cylinder portion 11 is not contaminated.

[0012] The top of the cylindrical casing 1 is above ground. A lid 13 is placed on the top of the inner cylindrical portion 12 to prevent dust and other foreign matter from entering the inside of the inner cylindrical portion 12.

[0013] (heat transfer fluid) The heat transfer fluid B is preferably an antifreeze (brine) so as to prevent freezing inside the heat transfer passage 41 in winter, and contains an antifreeze such as ethylene glycol as a main component. In order to be more environmentally friendly, it is also possible to use water as the heat transfer 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 122. The drive shaft 2 penetrates the inner cylinder bottom 122 and reaches the outer cylinder 11. The thrust bearing 22 of the inner cylinder bottom 122 allows the drive shaft 2 to rotate freely while maintaining watertightness.

[0015] (Heat medium flow path) The inner cylinder 12 is provided with a heat medium passage 41 that sends the heat medium fluid B out of the cylindrical casing 1 and returns it to the inner cylinder 12. In the first embodiment, there are two heat medium passages 41, one of which sends the heat medium fluid B to the parking lot X1, and the other of which sends the heat medium fluid B to the facility X2. In both paths, the heat medium fluid B is sucked up from the intake port 41a by a pump P. Then, the heat (hot heat or cold heat) of the heat medium fluid B is exchanged and returned to the inner cylinder 12 again from the exhaust port 41b. The heat transfer medium flow path 41 heading to the parking lot X1 is mainly used in winter to melt snow. The heat transfer medium flow path 41 heading to the facility X2 is used in both summer and winter. In summer, the heat transfer fluid B is used as a cold source, and is heat exchanged in the heat pump HP and used for air conditioning or cooling. In addition, in winter, heat transfer fluid B is used as a heat source, and heat is exchanged in the heat pump HP and used for hot water production, heating, etc.

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

[0017] (Stirring device for the inner cylinder) In the first embodiment, the propellers (agitating device) 31 are attached to one drive shaft 2 at two locations inside the inner cylinder 12 and one location inside the outer cylinder 11. The drive shaft 2 is rotated by a motor M to rotate the propeller (agitating device) 31 and agitate the heat transfer fluid B and groundwater W.

[0018] Heat transfer fluid B is sucked up by pump P from intake port 41a provided in inner cylinder 12 through heat transfer passage 41, undergoes heat exchange outside cylindrical casing 1, and is returned again from exhaust port 41b to inner cylinder 12. This circulation of heat transfer fluid B causes temperature unevenness in heat transfer fluid B in inner cylinder 12, impairing the efficiency of heat exchange with groundwater W in outer cylinder 11. Propeller (agitator) 31 acts to eliminate this temperature unevenness and improve heat exchange efficiency.

[0019] (Stirring device for outer cylinder) In the first embodiment, the drive shaft 2 penetrates the inner cylinder bottom 122 and reaches the outer cylinder 11. The propeller (agitator) 31 is attached to the drive shaft 2 protruding into the outer cylinder 11, and agitates the groundwater W in the outer cylinder 11. Fresh groundwater W always flows into the inside of the outer cylinder 11 from the water holes 111 evenly provided in the lower region of the outer cylinder 11. The groundwater W in the outer cylinder 11 is heated or cooled by the heat (cold or hot) of the heat transfer fluid B in the inner cylinder 12, causing temperature unevenness. The propeller (agitator) 31 has the effect of eliminating temperature unevenness by agitating the groundwater W in the outer cylinder 11, and promoting the inflow of fresh groundwater W.

[0020] In order to promote the inflow of fresh groundwater W, it is preferable to employ a Bernoulli flow agitator or an agitator 3 having centrifugal blades. These agitators 3 have a strong effect of discharging fluid in the horizontal direction, and can direct the flow of groundwater W to the water holes 111 provided around the outer cylinder 11. These agitators 3 can promote the exchange of groundwater W by this effect.

[0021] 2 is an explanatory diagram of a conventional geothermal energy utilization device 8. The conventional geothermal energy utilization device 8 draws up groundwater W from a groundwater intake port 51a and sends it to a heat exchanger of a heat pump HP in facility X2 via a groundwater flow path 51. The groundwater W that has been heat exchanged through the heat pump HP passes through the groundwater flow path 51 again and returns to the inside of the outer cylinder 11 from a groundwater discharge port 51b. In the conventional geothermal energy utilization device 8, the groundwater W in the outer cylinder 11 is not stirred using a stirring device 3. The reason for this will be explained.

[0022] The wall of the outer cylinder 11 has a water passage hole 111, through which pebbles and sand flow from the aquifer into the inside of the outer cylinder 11. The stirring device 3 stirs up the pebbles and sand. The stirred up pebbles and sand are sucked in from the groundwater intake port 51a, clogging the heat exchanger of the heat pump HP and causing trouble. It is very difficult to remove the foreign matter in the heat exchanger, and in the worst case, the entire heat exchanger must be replaced. In the conventional geothermal energy utilization device 8, as in the geothermal energy utilization device 8 of the first embodiment, unevenness in temperature occurs in the groundwater W in the outer cylinder 11, but this trouble could not be prevented and the stirring device 3 could not be used.

[0023] In the first embodiment of the present invention, the groundwater W is not sent to the heat pump HP, which is environmentally friendly. In addition, since the groundwater W can be agitated, the first embodiment has a significantly improved heat utilization efficiency compared to the conventional geothermal energy utilization device 8.

[0024] (Type of mixing device) The agitator 3 is not limited to the propeller 31. For example, using a Bernoulli flow agitator that creates a liquid flow by a pressure difference caused by centrifugal force has the following advantages. A Bernoulli flow agitator sucks up fluid from above and below and discharges the fluid horizontally. A Bernoulli flow agitator can perform very efficient mixing because it agitates fluid in both the vertical and horizontal directions. Agitator 3 equipped with centrifugal blades is also similar to a Bernoulli flow agitator, and has the effect of sucking in fluid from the axial direction (vertical direction) and discharging fluid horizontally, and can be expected to have the same effect as a Bernoulli flow agitator.

[0025] In the present invention, the drive shaft 2 is not essential. The agitator 3 may be an air pump or the like that does not use the drive shaft 2. Furthermore, if a watertight agitator 3 is used and power is supplied directly through a power cable, the drive shaft 2 and the motor M are not necessary. The agitator 3 is sufficient as long as it can agitate the fluid, and may be, for example, a pump that generates a water flow. The type of agitator 3 is appropriate. Various methods can be adopted for power supply to the agitator 3, such as a mechanical supply method using a drive shaft 2, a method of directly supplying power through a power cable, a method of sending air, and a method of sending only a water flow using an external pump. The method can be selected appropriately according to the purpose, such as low cost and easy maintenance.

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

[0027] The upper cylinder portion 14 stores a heat transfer fluid B inside. The lower cylinder portion 15 has a large number of water holes 111 on the outer periphery, and is filled with groundwater W flowing in from an aquifer. The partition wall 16 separates the upper cylinder portion 14 and the lower cylinder portion 15, and functions as a heat exchanger from the groundwater W in the lower cylinder portion 15 to the heat transfer fluid B in the upper cylinder portion 14. For this reason, the partition wall 16 is preferably made of a material with high thermal conductivity, such as aluminum. In order to improve heat transfer, it is a preferred embodiment to provide fins on the surface of the partition wall 16 to increase the surface area.

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

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

[0030] Moreover, the first and second embodiments are common in that they each include a portion for storing heat transfer fluid B and a portion located in an aquifer for storing groundwater W. In the first embodiment, it is sufficient that the stirring device 3 is provided in either or both of the outer cylindrical portion 11 and the inner cylindrical portion 12. Moreover, in the second embodiment, it is sufficient that the stirring device 3 is provided in either or both of the upper cylindrical portion 14 and the lower cylindrical portion 15. The stirring device 3 can contribute to improving thermal efficiency even if it is provided in only one of them, and it is more preferable that it is provided in both.

[0031] Although the 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 the present invention also includes design changes and the like that do not deviate from the gist of the present invention. Furthermore, the above-described embodiments can be combined by utilizing each other's technologies, so long as there are no particular contradictions or problems in the purpose, configuration, or the like. [Explanation of symbols]

[0032] 1. Cylindrical casing 11 External cylinder 111 Water Vent 12 Inner cylinder 122 Inner cylinder bottom 13 Lid 14 Upper cylinder part 15 Lower cylinder part 16 Partition Wall 2 Drive shaft 22 Thrust bearing 3. Mixing device 31 Propeller (mixing device) 41 Heat transfer medium flow path 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 Medium 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 in the ground and has an upper cylindrical portion and a lower cylindrical portion. There is a partition wall between the upper and lower cylinders, separating the top and bottom. The upper cylinder has a heat transfer fluid inside. The lower cylinder is provided with a groundwater passage hole. A geothermal energy utilization device characterized in that it has an agitator in either or both of an upper cylindrical portion and a lower cylindrical portion.

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