JP3970505B2 - Heat pump system using groundwater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pump system using groundwater suitable mainly for a house.
[0002]
[Prior art]
From the perspective of preventing global warming, there is an urgent need to reduce CO2 emissions associated with energy consumption. However, the energy consumption in the consumer sector is increasing year by year, and out of all the energy from new housing construction to dismantling and disposal. 80% is consumed at the time of residence (use). Furthermore, about 60% of this is consumed by air conditioning and hot water supply, and most of it is covered by fossil fuels. Therefore, reduction of the consumption or replacement with natural energy is desired.
[0003]
Only solar energy is currently established and popularized as a means of using natural energy in houses. However, the use of solar energy is subject to uncertainties such as being easily affected by the weather and not being able to ensure sufficient solar radiation in densely populated areas.
[0004]
[Problems to be solved by the invention]
In contrast, geothermal heat, one of the natural energies, maintains a stable temperature near the average annual temperature in the region throughout the year, so it is cooler than the outside air in summer and hot in winter. Such geothermal heat is used on a trial basis in buildings, public facilities, etc., but heat is generally recovered by laying a heat-medium pipe, requiring extensive construction, and initial. Due to its high cost, it is not suitable for residential use.
[0005]
On the other hand, groundwater as a geothermal pumping medium is widely distributed nationwide and can be easily acquired by constructing wells. By using such groundwater, it is simpler and the initial cost can be kept lower than the heat recovery method in which a large number of heat transfer pipes are laid in the ground. Cooling using groundwater has become widespread as a well water fan coil cooler before the heat pump goes around, and wells and cooling technology have been established to some extent. Recently, an attempt has been made to use groundwater pumped from a well for melting snow and keeping a greenhouse warm.
[0006]
However, the current mainstream boring well has a problem that the construction cost is still high for widespread use in ordinary houses, and when groundwater is pumped in large quantities, it causes problems such as land subsidence. In addition, heating using groundwater is not performed at all. Therefore, the present condition is that the air-conditioning and hot-water supply system for houses using groundwater has not been established yet.
[0007]
Therefore, in view of the above, an object of the present invention is to provide a heat pump system using groundwater that does not cause adverse effects such as land subsidence and has a simple structure and is inexpensive.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the heat pump system using groundwater of the present invention has a plurality of wells in the ground, and the groundwater in the subsurface aquifer pumped from some of the wells is heated with the refrigerant. After being used for exchange, it is injected into another well and returned to the underground aquifer.
[0009]
Specifically, each well is a shallow well having a depth of 10 m or less, and is constructed by a driving method in which a casing with a strainer is directly driven from the ground. The casing has a plurality of water collection ports on the outer periphery of the strainer, a sand intrusion prevention wire mesh is wound around the outer periphery, and an arrowhead is attached to the tip of the strainer. Each well is provided with an interval of at least 8 m.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 and 2 show an entire circuit of a heat pump system applied to a house according to an embodiment of the present invention. In the figure, (1) is a compressor that compresses refrigerant, (2) is a four-way valve that switches between a cooling cycle and a heating cycle, (3) is an outdoor heat exchanger, and (4) is in the interior of a house. It is an indoor heat exchanger such as a fan coil cooler arranged, and these are connected by a pipe (5) to constitute a refrigerant circuit (6). The main parts of the refrigerant circuit (6) such as the compressor (1) and the outdoor heat exchanger (3) excluding the indoor heat exchanger (4) are housed in a single package as an outdoor unit.
[0011]
A groundwater circuit (10) is connected to the outdoor heat exchanger (3). This groundwater circuit (10) is constructed by connecting two wells, a pumping well (12) and a reduction well (13), provided on the ground (11), with a groundwater pipe (15) equipped with a pump (14). Has been.
[0012]
Generally, there are a borehole method and a driving method for well construction. The boring method is used for the construction of deep wells with a large diameter exceeding 10 m, and after excavating the ground beforehand by boring and inserting a casing with a strainer, the gap is filled with a filter medium such as gravel. With this boring method, the strainer can be installed reliably in the aquifer and deep well construction with excellent filtration performance is possible, and groundwater with good water quality can be obtained from this deep well. There is a problem such as high. On the other hand, the driving method is used for the construction of shallow wells having a small diameter and a depth of 10 m or less, and the construction cost is halved because it is a simple method of simply driving a casing with a strainer from the ground. However, in recent years, it has been difficult to obtain good quality groundwater from shallow wells, and there is a problem that the water quality is not stable. In the case of domestic wells, since the importance of water quality is particularly important, deep wells made by the boring method are currently the mainstream.
[0013]
However, since the heat pump system of the present invention requires two wells (12) and (13) as described above, it is important to reduce the well construction cost in consideration of the initial cost including other equipment. . Moreover, since only the heat of groundwater is used, it is not necessary to clear the water quality standard of tap water, and it is sufficient if the required amount of water is obtained. Accordingly, the pumping well (12) and the reduction well (13) are shallow wells having a depth of 10 m or less constructed by the driving method.
[0014]
Here, the construction of the pumping well (12) and the reduction well (13) by the driving method will be described. First, the surface layer of the ground (11) is simply excavated, and a strainer as shown in FIG. (20) Directly drive the attached casing (21). The strainer (20) has a large number of water collection ports (22) and (22) on the outer periphery, a sand intrusion prevention wire mesh (24) is wound around the outer periphery, and an arrowhead (25) is attached to the tip. . At the time of the above driving, the strainer (20) is driven until it reaches the aquifer (30) of the ground (11).
[0015]
When the driving is completed, the amount of pumped water is confirmed, and if there is no problem, the excavated portion is backfilled. Thereby, the construction of the pumping well (12) and the reduction well (13) is completed.
[0016]
In the case of such shallow wells (12) and (13), the temperature effect of the injected water reaches a wide range in a relatively short time. growing. In order to be completely unaffected by heat in shallow wells (12) and (13), the well spacing must be at least 15m, but such a well spacing can be secured on the site of a general detached house. Can not. However, it has been experimentally found that the influence of the heat of the injected water on the cooling and heating efficiency cannot be ignored at well intervals of about 4 m or less. Therefore, the interval between the wells (12) and (13) is set to at least 8 m so that it can be secured in a general detached house and is not easily affected by the cooling and heating efficiency.
[0017]
The groundwater pipe (15) has a structure in which a pumping pipe (35) inserted into the pumping well (12) and an injection pipe (36) inserted into the reduction well (13) are connected by a connecting pipe (37). It has become. The connecting pipe (37) is provided with various devices such as the pump (14) and a sand remover (not shown). The connecting pipe (37) is connected to the outdoor heat exchanger (3).
[0018]
In the heat pump system configured as described above, during cooling, as shown in FIG. 1, the refrigerant compressed by the compressor (1) is led to the outdoor heat exchanger (3) through the four-way valve (2), and heat of condensation is obtained. It becomes a liquefied state while diverging. On the other hand, in the groundwater circuit (10), the groundwater in the underground aquifer (30) pumped from the pumping well (12) by driving the pump (14) is guided to the outdoor heat exchanger (3). In the outdoor heat exchanger (3), heat is exchanged between the liquefied high-temperature refrigerant on the refrigerant circuit (6) side and the low-temperature ground water on the groundwater circuit (10) side. The refrigerant after the heat exchange is led to the indoor heat exchanger (4) while being expanded to be in a gasified state, and the room is cooled by the heat of vaporization at this time, and again passes through the four-way valve (2) to the compressor ( Returned to 1). The groundwater after heat exchange is injected into the reduction well (13) and reduced to the underground aquifer (30).
[0019]
At the time of heating, as shown in FIG. 2, the four-way valve (2) on the refrigerant circuit (6) side is switched, and the refrigerant compressed by the compressor (1) passes through the four-way valve (2) to the indoor heat exchanger. It is led to (4), it becomes a liquefied state while dissipating the condensation heat, and the room is heated by the condensation heat at this time. The refrigerant that has expanded into a gasified state after the heating is exchanged with the high-temperature groundwater on the groundwater circuit (10) side in the outdoor heat exchanger (3). The refrigerant after the heat exchange is returned to the compressor (1) through the four-way valve (2). The groundwater after heat exchange is injected into the reduction well (13) and reduced to the underground aquifer (30), as in the case of cooling.
[0020]
In the case of such a heat pump system using groundwater, it is possible to obtain thermal energy about six times the power consumption. That is, the coefficient of performance (COP) is “6”, and a heat pump system with high heat exchange efficiency and excellent energy saving effect can be obtained as compared with an air heat source heat pump system using outside air with a coefficient of performance of “3”. it can. In addition, groundwater pumped from the aquifer (30) is used as a heat source for heat exchange of the refrigerant, and then returned to the aquifer (30), preferably the same aquifer (30). Land subsidence due to pumping can be prevented.
[0021]
In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added to the said embodiment within the scope of this invention. For example, as a heat exchanger for hot water supply instead of an indoor heat exchanger, a heat pump system may be used not only for air conditioning but also for hot water supply in a house. In addition, the pumping well and the reduction well are not limited to a single well, and may be constituted by a plurality of wells.
[0022]
【The invention's effect】
As is clear from the above description, in the present invention, a plurality of wells are provided in the ground, and the groundwater pumped up from the underground aquifer is returned to the underground aquifer again, which causes problems such as ground subsidence. Therefore, it is possible to provide a heat pump system with high heat exchange efficiency using groundwater that maintains a stable temperature throughout the year as a heat source for heat exchange of the refrigerant.
[0023]
In addition, since these wells are shallow wells constructed by the driving method, they can be constructed more easily than when a deep well is constructed by the boring method, and the construction cost is greatly reduced. can do. Thereby, it can be set as the system which can be spread widely also in a common house. In addition, since the well interval is 8 m or more, even if groundwater is reduced to the well on the reduction side, the thermal effect of the groundwater hardly reaches the well on the upper side, thereby improving the efficiency of air conditioning and hot water supply. be able to.
[Brief description of the drawings]
FIG. 1 is a diagram showing an entire circuit during cooling of a heat pump system according to an embodiment of the present invention.
FIG. 2 is a diagram similarly showing the entire circuit during heating.
FIG. 3 is a view showing a well constructed by a driving method.
[Explanation of symbols]
(11) Ground
(12) (13) Well
(20) Strainer
(21) Casing
(30) Underground aquifer

Claims (2)

A number of wells are provided in the ground, and the groundwater from the groundwater aquifer pumped from some of the wells is used for heat exchange with the refrigerant and then injected into other wells to be returned to the groundwater aquifer. It is a heat pump system using groundwater that is made to be, each well is a shallow well within a depth of 10 m, each well is constructed by a driving method in which a casing with a strainer is directly driven from the ground, In the casing, there is a plurality of water collecting ports on the outer periphery of the strainer, and a sand net preventing wire mesh is wound around the outer periphery, and an arrowhead is attached to the tip of the strainer . Heat pump system. The heat pump system using groundwater according to claim 1, wherein each well is provided with an interval of at least 8 m.

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