JP2016070530A - Environmentally-friendly underground water heat utilization system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environmentally-friendly underground water utilization system capable of minimizing impact on an underground environment in terms of both a water temperature and water quality when sending underground water which is pumped up from the ground and used for heat exchange back to the ground.SOLUTION: An environmentally-friendly underground water utilization system comprises: a production well 1 to pump up underground water from the ground; a heating and cooling facility which uses thermal energy of the underground water pumped up through the production well 1; a heat regulator which brings a temperature of the underground water after being used in the heating and cooling facility close to an original temperature thereof; and a reflux pipe 18 to send the underground water which passes through the heat regulator back to the production well. A heating and cooling system mounted with a water-heat type heat pump 16 which uses the underground water as a heat source is best for the heating and cooling facility in terms of convenience. The heat regulator preferably has: a heat regulation hole 9 with a heat exchanger 11 installed therein; or heat exchange pipes horizontally arranged in the ground. Also, the reflux pipe 18 may have a plurality of discharge ports to allow the used underground water to be sent immediately below an underground water surface in the production well 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a groundwater heat utilization system that uses the thermal energy of groundwater pumped from environment-friendly groundwater for air conditioning.

  Currently, air-cooled heat pumps using air as a heat source are widely used in Japan from the viewpoint of energy saving. However, the air-cooled heat pump uses outdoor air as a heat source, cools indoor air using outside air of 30 ° C. or more in summer, and heats indoor air using outside air at a temperature below freezing in winter. On the other hand, the groundwater heat utilization system can efficiently cool indoor air in summer and warm in winter by using stable groundwater as the heat source throughout the year. It is attracting attention as a renewable energy with a low load.

  And in areas blessed with groundwater resources, the groundwater used for heat exchange is often drained as is, but generally from the viewpoint of conserving groundwater resources, a well (pump well) for pumping up groundwater is used. In addition, a method of excavating a well (reduction well) reaching the underground aquifer and returning the drainage to the aquifer has been adopted (Non-Patent Document 1).

  And in the groundwater heat utilization system using a reduction well, various systems are proposed by patent document 1 etc. from viewpoints, such as prevention of clogging of a reduction well.

JP 2011-21804 A

"Geothermal heat pump system", Ministry of the Environment, March 2013

  In the conventional groundwater heat utilization system shown in Non-Patent Document 1, the temperature of groundwater after heat exchange increases about 5 degrees in summer and decreases about 5 degrees in winter. Returning water with such a temperature difference directly to the aquifer will cause a large thermal shock to the underground environment, causing chemical, physical and biological effects in the ground. There are many cases where this is a concern. However, since there is no established method for assessing the impact on the underground environment and it is difficult to dispel concerns, there are many cases where the plan is neglected, which is a major issue in spreading the groundwater heat utilization system in Japan. It has become one of the.

  Also, even if the drainage is returned to the aquifer using the reduction well, although it is close, the pumping point and the reduction point are different. In many cases, no consent can be obtained from the project, which is one of the major issues in spreading groundwater heat utilization systems in Japan.

  In view of the above circumstances, the present invention uses the groundwater pumped up from the ground for heat exchange in the groundwater heat utilization system, and then returns it to the state close to the original groundwater temperature as much as possible. By returning, the thermal shock to the underground environment (thermal shock) is minimized, and the quantitative balance of groundwater at the pumping well installation point is reduced to zero, eliminating the impact of water volume on the surrounding existing wells. The purpose is to provide an environment-friendly groundwater heat utilization system that enables this.

  The groundwater heat utilization system according to the invention of claim 1 includes a pumping well for pumping up groundwater from the ground, a heating / cooling facility for cooling / heating using the thermal energy of the groundwater pumped from the pumping well, and the cooling / heating facility. It has a heat buffer device for bringing the temperature of the groundwater after use close to the original groundwater temperature, and a reduction channel for returning the groundwater after use that has passed through the heat buffer device to the pumping well.

  Invention of Claim 2 is the groundwater heat utilization system of Claim 1, Comprising: The said air conditioning equipment has the heat pump air conditioning system by the water heat source heat pump which uses groundwater as a heat source.

  Invention of Claim 3 is a groundwater heat utilization system of Claim 1 or Claim 2, Comprising: It has a heat exchanger which installed the heat exchange pipe planarly in the ground as said heat buffering device. And

  Invention of Claim 4 is a groundwater heat utilization system of any one of Claims 1-3, Comprising: It has the heat buffer hole which installed the heat exchanger as said heat buffer apparatus, It is characterized by the above-mentioned. .

  Invention of Claim 5 is a groundwater heat utilization system of any one of Claims 1-4, Comprising: Plural for making it possible to return the groundwater after utilization to just under the groundwater surface of a pumping well The discharge passage is provided in the reduction flow path.

  According to the groundwater heat utilization system of the present invention, the groundwater after heat exchange can be returned to the ground close to the original groundwater temperature by the thermal buffer, and the thermal shock (thermal shock) to the ground by the reduced water can be reduced. It can be minimized.

  In addition, according to the groundwater heat utilization system of the present invention, by returning the entire amount of groundwater pumped from the pumping well to the pumping well again, the quantitative balance of groundwater becomes zero, and the influence on the groundwater level of the surrounding wells is eliminated. Is possible.

  In addition, according to the groundwater heat utilization system of the present invention, when groundwater after heat exchange is returned to the pumping well immediately following the groundwater surface following the fluctuation of the groundwater level of the pumping well, the groundwater absorbs heat during cooling. Compared to the original groundwater, it reduces the cooling efficiency by minimizing the rise in the temperature of the groundwater to be pumped by making the hot water, which is light and hot, stay near the groundwater surface to form a thermocline. At the same time, after the temperature layer has cooled down and the temperature difference from the original groundwater has become slight, the temperature layer disappears and mixing proceeds in the pumping well, thus minimizing thermal shock to the groundwater. It is possible to limit it to the limit.

  In addition, when collecting heat from groundwater during heating, thermal disturbance in the reduction well due to sedimentation of cold water mass is caused by flowing reduced water that is heavier at a lower temperature than the original groundwater into the reduction well from near the groundwater surface. This increases the mixing efficiency in the pumping well, prevents the formation of cold water pools at the bottom of the pumping well, and minimizes groundwater temperature drop. Therefore, it is possible to prevent a decrease in heating efficiency and at the same time to minimize a thermal shock to the groundwater.

It is a figure which shows the outline | summary of the groundwater heat utilization system of this invention. It is a figure which shows the Example which switches a reduction pipe discharge port following a groundwater level. It is explanatory drawing of the cooling process of a thermocline. It is a figure which shows the outline | summary of another embodiment of a thermal shock absorber.

Embodiments of the present invention will be described below with reference to the drawings.
In the present invention, as shown in FIG. 1, the pumping well 1 is a well for use of groundwater heat, and a casing 2 with a water intake strainer is inserted therein.

  Further, as shown in FIG. 1, a water level sensor 19 for measuring the water level and a pumping pump 3 are installed in the casing 2 and connected to the pumping pipe 4 so that groundwater can be pumped up to the ground. The pump 3 is interlocked with the heat pump 16 by a control circuit, and starts operating as soon as the heat pump 16 operates, and stops operating as soon as the heat pump 16 stops operating. In addition, a pump for water pumping can also be installed on the ground.

  The groundwater pumped up is subjected to heat exchange between the groundwater and the heat medium in the heat medium flow path (outward) 13 by the heat exchanger 5 and then drained through the drain pipe 6. A water pump 7 is installed in the drain pipe 6 and led to a heat exchanger 11 installed in a heat buffer hole 9 of the heat buffer device. Further, a casing 10 with a strainer is installed in the heat buffer hole 9, and a check valve 8 is installed between the water pump 7 and the heat buffer hole 9 to prevent backflow due to siphon action or the like. It is said.

  In this embodiment, the heat exchanger 11 is a resin heat exchange pipe such as high-density polyethylene having an inner diameter of about 20 to 30 mm, and the waste water after heat exchange pumped by the water pump 7 is allowed to flow into the heat exchange pipe. The heat exchange is performed without mixing with the groundwater in the heat buffer hole, and the temperature difference from the original groundwater is reduced. Note that the groundwater temperature in the heat buffer hole rises during cooling and decreases during heating due to heat exchange with the waste water, but a large amount of groundwater in the heat buffer hole has a very large heat capacity, so the temperature change is slight. In addition, when a groundwater heat utilization system is introduced in an alluvial fan, since the flow of groundwater is fast and the time during which the groundwater stays in the heat buffer hole is short, the temperature change is less likely to occur and is particularly effective. In addition, a thermal response test (TRT test) is performed in advance, and it is possible to grasp the relationship between the amount of heat exchange and the temperature change of groundwater in the heat buffer hole. It is better to design in a range where the shock is small.

  After heat buffering by the heat exchanger 11, the waste water is returned to the pumping well 1 through the reduction pipe 18. An electromagnetic valve 12 is installed in the reduction pipe 18, and the reduction pipe is closed to prevent backflow when the pump is stopped.

  The heat medium flow path (outward) 13 is connected to the heat exchanger 5 to guide a heat medium (such as an antifreeze solution of 25% ethylene glycol solution) to the heat exchanger 5, and to the heat medium side outflow portion of the heat exchanger 5. A heat medium flow path (return) 14 is connected, the other end of the heat medium flow path is connected to the heat pump 16, and the heat medium after heat exchange with the ground water is performed in the heat pump 16 by the heat exchanger 5. The configuration is back. In addition, a circulation pump 15 is installed in the heat medium flow path (return) 14. In this embodiment, the heat pump 16, the heat medium flow path (outward) 13, the heat exchanger 5, and the heat medium flow path (return) 14 are provided. The heat medium circulates in the closed circuit.

  The heat collected from the groundwater through the heat exchanger 5 is guided to the secondary cold / hot water circuit 17 by the heat pump 16, and by an air conditioner such as a fan coil unit connected to the cold / hot water circuit 17. It is configured to perform air conditioning. The embodiment shown in FIG. 1 assumes a heat pump 16 that performs inverter control. However, a buffer tank may be installed in the middle of the hot / cold water circuit 17 as necessary, such as when using a heat pump that performs on / off control. The configuration is as follows.

FIG. 2 is a diagram showing an embodiment in which the outlet of the reduction pipe 18 is switched following the groundwater level.
In this embodiment, a commercially available underwater solenoid valve (SV1 to SV4) is used to follow changes in the groundwater level. Based on the groundwater level measured by the water level sensor 19 installed in the pumping well 1 in FIG. 1, it is identified which groundwater level is located in the groundwater level zone shown in FIG. By opening the solenoid valve corresponding to the zone and returning the groundwater from the reduction pipe 18 into the pumping well, the discharge position is switched in accordance with the change in the groundwater level. In addition, the installation interval of the solenoid valve and the setting of the groundwater level zone are affected by the speed of groundwater flow and the amount of groundwater pumped. Therefore, it is recommended to carry out field tests in advance and decide based on the results.

FIG. 3 is an explanatory diagram of the cooling process of the thermal stratum.
In the cooling system using the groundwater heat utilization system, after the target facility has been cooled to the specified temperature, it is only necessary to cool the amount of heat added by heat radiation, etc., so there is no need to constantly pump up the groundwater and exchange heat. Normally, intermittent operation is performed as shown in FIG. Accordingly, when the cooling facility is operated and the target facility is cooled by absorbing heat into the pumped-up groundwater, the warm and light groundwater after use is returned from the reduction pipe 18 directly below the groundwater level of the pumping well 1. A thermocline (thermocline) is formed near the surface. Thereafter, when the target facility is cooled to a predetermined temperature and the pumping pump 3 is stopped, the temperature climbing layer is cooled by groundwater or the like under the climbing layer and gradually shrinks, and finally disappears.

  The embodiment of the present invention disclosed above is merely an example. The technical scope of the present invention is shown by the claims, and includes a technical configuration evaluated as equivalent to the description. For example, in the embodiment of the present invention, the heat pump 16 is used. However, depending on the use such as cooling of the grain warehouse, the heat medium that has exchanged heat with the ground water in the heat exchanger 5 is used without using the heat pump. You may guide to the cold / hot water circuit 17 and use heat.

  Moreover, in the Example of this invention, although it is set as the structure which heat-exchanges between groundwater and a heat medium through the heat exchanger 5, the quality of groundwater is determined in the water quality guidelines for refrigeration air conditioning equipment (Japan Refrigeration and Air Conditioning Industry Association). If the water quality standards are met and there is no concern about the corrosion of pipes or other equipment due to the quality of groundwater or the generation of scale, the heat exchanger 5 is omitted and the groundwater is directly supplied to the heat medium flow path (outward) 13 and heat. There is no problem even if it flows through the medium flow path (return) 14.

  In the embodiment of the present invention, a heat buffering hole is installed as a heat buffering device, and heat is buffered by heat exchange using a resin heat exchange pipe. It is only necessary to cool the drainage water after replacement to near the original groundwater temperature and to warm to the original groundwater temperature at the time of heating. For example, hot spring drainage or solar heat may be heated and surface water may be used for cooling. In addition, when a sufficient site can be secured, as shown in FIG. 4, it is possible to install a resin heat exchange pipe in the ground and exchange heat with the ground to buffer the heat. Good. In addition to the resin heat exchange pipe, a coil-type heat exchanger using stainless steel, titanium, or the like may be used as the heat exchanger 11.

  Furthermore, in the embodiment of the present invention, in order to switch the discharge position of the reduction pipe 18 so as to be directly below the groundwater surface in accordance with the change in the groundwater level, the underwater sensor 19 and the underwater electromagnetic valve shown in FIG. However, any configuration is possible as long as the discharge port can be switched according to the water level. For example, a float switch or an electrode rod may be used instead of the water level sensor. In addition, the discharge port of the reduction pipe 18 may be configured so as to switch the flow path by installing an electromagnetic valve on the ground instead of the underwater electromagnetic valve.

DESCRIPTION OF SYMBOLS 1 Pumping well 2 Casing 3 Pumping pump 4 Pumping pipe 5 Heat exchanger 6 Drain pipe 7 Water pump 8 Check valve 9 Heat buffer hole
10 Casing
11 Heat exchanger
12 Solenoid valve
13 Heat transfer channel (outward)
14 Heat transfer channel (return)
15 Circulation pump
16 Heat pump
17 Cold / hot water circuit
18 Reduction tube
19 Water level sensor

Claims (5)

  A pumping well for pumping groundwater from the ground, a heating / cooling facility that uses the thermal energy of the groundwater pumped from the pumping well, and a temperature of the groundwater after using the cooling / heating facility to the original groundwater temperature. A groundwater heat utilization system comprising: a heat buffer device for approaching, and a reduction passage for returning groundwater after passing through the heat buffer device to a pumping well. The groundwater heat utilization system according to claim 1,
The air conditioning system includes a heat pump air conditioning system using a water heat source heat pump that uses groundwater as a heat source. A groundwater heat utilization system according to claim 1 or 2,
A groundwater heat utilization system comprising a heat exchanger in which a heat exchange pipe is installed in the ground as the heat buffer. The groundwater heat utilization system according to any one of claims 1 to 3,
A groundwater heat utilization system having a heat buffering hole provided with a heat exchanger as the heat buffering device.   It is a groundwater heat utilization system of any one of Claims 1-4, Comprising: The several discharge port for enabling return of the groundwater after utilization to the underground water surface of a pumping well is said reduction | restoration flow path A groundwater heat utilization system characterized by comprising:

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