JP2007010276A - Underground heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground heat exchanger generating no heat exchange loss owing to high heat exchange efficiency and for making it easy to process the underground heat exchanger, bore a hole for burying the underground heat exchanger and conduct a burial work. <P>SOLUTION: The underground heat exchanger buried under ground for adjusting temperature of a heat medium flowing inside by subterranean heat is equipped with a resin supply pipe part 1 through which the heat medium spirally flows down near an earth surface and a return pipe part 2 for returning the heat medium to above the ground. The supply pipe part 1 is wound so that its diameter is sequentially enlarged downward and winding form of the supply pipe part 1 is circle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an underground heat exchanger.

  Since the underground is below a certain depth, the temperature is almost constant throughout the year. The underground heat exchanger is used to collect this underground heat via a heating medium, and the whole is U-shaped so that the heating medium is lowered from the ground to the deep part of the ground and then reversed and returned to the ground. The reciprocating pipe section is provided, inserted into the excavated hole and buried, and heat exchange is performed between the underground and the heat medium. The reciprocating pipe section has corrosion resistance, durability, etc. From the point, resin pipes are used.

JP 2001-289533 A

  In order to obtain the amount of heat necessary for the above U-shaped round-trip pipe section, a vertical hole must be dug for a long time with a special excavator toward the deep layer, and also prevention of collapse of the hole, mud, spring water, etc. This process is also necessary, and there is a problem that it is very laborious and time consuming and increases the cost. Therefore, if you fill in one hole with a large U-shaped round-trip pipe capacity, or if you fill multiple holes in one hole, you will collect heat in a narrow area in the ground, For example, in winter, the amount of heat per unit volume taken from the ground increases and it takes a long time to recover the underground temperature, so the amount of heat collected continues to decline and air conditioning operation cannot be performed, and antifreeze must be used to prevent freezing. Therefore, there is a problem that environmental pollution occurs. Also, in the U-shaped round-trip pipe section, the heating medium flows through the same path in both the forward path and the return path. For example, in the winter season, when the heating medium returns to the ground surface, the heating medium whose temperature is adjusted is dissipated near the ground. There is a problem that heat loss occurs.

  In order to solve the above-mentioned problems, the present invention is a subsurface heat exchanger that adjusts the temperature of a heat medium that is buried in the ground and that flows inside by using ground heat, and the heat medium descends in a spiral shape near the ground surface. And a return pipe section for returning the heat medium that has flowed out of the forward pipe section to the ground, and opposed to the ground surface at a predetermined interval, and the heat medium The main feature is that it comprises a pair of resin-made forward pipe sections that flow while meandering in a meandering manner, and a return pipe section that returns the heat medium that has come out of the forward pipe sections to the ground.

According to the invention of claim 1, the underground temperature up to a depth of about 1 m varies depending on the region, but is affected by the outside air and is low in winter and high in summer, but the heat medium collects heat (winter) and dissipates heat (summer). Since there is a possible temperature difference with respect to the ground, the outgoing pipe section 1 is embedded in the vicinity of the ground surface as a thin and long spiral, and the heat medium is flowed in a counter flow with respect to the geothermal flow, improving the heat exchange efficiency. Dispersed over a wide range in the ground and gradually exchanged heat, it is possible to obtain the amount of geothermal heat required to adjust the temperature of the heating medium, and to reduce the amount of geothermal heat per unit volume taken from the ground . Therefore, it is easy to recover the underground temperature, and long-term continuous air-conditioning operation is possible. Water that does not have to worry about environmental pollution can be used as a heat medium, and it is not necessary to use antifreeze. In addition, the outgoing pipe section 1 can be easily processed by winding only one seamless pipe, and it is wound in a spring shape so that it has elasticity, so it has excellent seismic isolation and durability against earthquakes. Is sufficient to prevent leakage of heat medium due to breakage. The return pipe section 2 may be short because it only needs to return the heat medium to the ground, there is no heat loss due to reheat exchange with the ground, and heat exchange efficiency is improved, so that the heat medium temperature is stabilized. It is only necessary to dig the burial hole in the outgoing pipe section 1 near the ground surface with a normal excavating machine such as a power shovel, and the construction can be facilitated by reducing the excavation time and cost.
According to the invention of claim 2, by changing the size of the diameter of the forward pipe section 1 for each turn, the overlapping part of the heat exchange area between the pipe sections is eliminated, and the heat exchange is performed uniformly over a wide range in the ground. Early recovery of underground temperature can be achieved, and heat exchange efficiency can be improved. In the forward pipe section 1 wound so as to gradually expand in diameter downward, the heat quantity in the ground increases and stabilizes as the depth increases, so that the diameter of the forward pipe section 1 is increased and the heat exchange amount is increased. By increasing, the heat exchange efficiency can be increased. Further, when the forward pipe portion 1 is filled, soil is piled up from the central portion of the diameter to form a mountain shape along the shape of the forward pipe portion 1 and can be easily filled without breaking the shape of the forward pipe portion 1. In the forward path pipe portion 1 wound so as to be gradually reduced in diameter toward the lower side, the embedding hole may be shaped like a bowl, so that it is easy to dig and construction becomes easier.
According to the invention of claim 3, when the forward pipe portion 1 has a round or polygonal winding shape, it can be dispersed in a wider range in the ground and heat can be collected little by little, and the underground temperature can be easily recovered. When the outgoing pipe section 1 is an elliptical or rectangular polygonal winding shape, it can be easily embedded in a narrow and long land.
According to the invention of claim 4, the underground temperature up to about 1 m depth varies depending on the region, but is affected by the outside air and is low in winter and high in summer, but the heat medium collects heat (winter) and dissipates heat (summer). Since there is a possible temperature difference with respect to the ground, the forward pipe section 1 is embedded in the vicinity of the ground surface as a narrow and long meander, and a heat medium is flowed in a counter flow with respect to the geothermal flow, improving the heat exchange efficiency. Dispersed over a wide range in the ground and gradually exchanged heat, it is possible to obtain the amount of geothermal heat required to adjust the temperature of the heating medium, and to reduce the amount of geothermal heat per unit volume taken from the ground . Therefore, it is easy to recover the underground temperature, and long-term continuous air-conditioning operation is possible. Water that does not have to worry about environmental pollution can be used as a heat medium, and it is not necessary to use antifreeze. Further, since the forward pipe section 1 has a meandering shape and is stretchable, it is excellent in seismic isolation, has sufficient durability against earthquakes, and prevents heat medium leakage due to breakage. The return pipe section 2 may be short because it only needs to return the heat medium to the ground, there is no heat loss due to reheat exchange with the ground, and heat exchange efficiency is improved, so that the heat medium temperature is stabilized. It is only necessary to dig the burial hole in the outgoing pipe section 1 near the ground surface with a normal excavating machine such as a power shovel, and the construction can be facilitated by reducing the excavation time and cost. Since the outward pipe sections 1 and 1 can be made to face each other and the width can be narrowed, it can be easily embedded in narrow and long land.
According to the invention of claim 5, the overlap of the heat exchange area between the pipe parts is eliminated by changing the width of the interval between the forward pipe parts 1 and 1 for each meandering, and heat exchange is performed uniformly over a wide range in the ground. By doing so, it is possible to achieve an early recovery of the underground temperature and to improve the heat exchange efficiency. In the forward pipe sections 1 and 1 that are arranged so that the interval gradually spreads downward, when the forward pipe sections 1 and 1 are filled, soil is piled up from the central portion of the interval, thereby following the shape of the forward pipe section 1. It can be easily filled without breaking the shape of the forward pipe section 1. In the forward pipe sections 1 and 1 that are arranged so that the interval is gradually narrowed downward, the embedding holes may be V-grooves according to the shape, so that the construction is easier to dig.
According to the invention of claim 6, since the forward tube portion 1 is a flat tube, heat transfer from the outer surface on the short diameter side to the heat medium in the central portion of the tube is fast, and the heat exchange efficiency is further improved. Since it is a flat tube, it is easy to bend, and the outgoing pipe part 1 can be easily formed in a spiral shape or a meandering shape.
According to the invention of claim 7, since the forward tube portion 1 is a flat tube and the long side is pointed, the heat medium becomes turbulent and heat transfer is promoted by forced convection, and the heat exchange efficiency is further improved.
According to the invention of claim 8, since the outer peripheral wall of the forward pipe section 1 is meandering, the heat transfer area is increased, and the turbulent flow effect of the heat medium can be further enhanced inside, thereby further improving the heat exchange efficiency.

  FIG. 1 and FIG. 2 show an embodiment of the underground heat exchanger according to the present invention, which is an underground heat exchanger that is buried in the ground and adjusts the temperature of the heat medium flowing inside through the underground heat. In addition, it includes a resin-made forward pipe portion 1 that flows while the heat medium descends in a spiral shape near the ground surface, and a return pipe portion 2 that returns the heat medium that has come out of the forward pipe portion 1 to the ground. . The average diameter of the winding shape of the forward pipe section 1 is set to a large curvature of at least about 2 m. The return pipe section 2 is made as thin as possible so that the heat medium can be quickly returned to the ground. In the example shown in the figure, the tube is erected along the inner diameter side of the forward tube portion 1 so as not to protrude from the outer diameter side, but may be erected on the outer diameter side. The forward pipe section 1 and the backward pipe section 2 are formed integrally with a single pipe or connected to separate pipes, and are buried in, for example, an embedding hole 3 drilled near the ground surface at a depth of about 3 m. The pipe part 1 and the return pipe part 2 are connected to a water-cooled heat pump 4 or the like, and a heat medium exchanged with the ground is circulated by the pump and used as heat source water for an air conditioner. In addition to using water as a heat medium, it is also free to use brine or other various liquids.

  The forward pipe portion 1 is wound so as to gradually increase in diameter downward, and the winding shape is circular or elliptical, and the forward pipe portion 1 is shifted in the left-right direction for each turn. As shown by the phantom line in FIG. 1, the buried soil becomes a mountain shape at the center of the diameter of the forward pipe portion 1 during the burying operation. It is made to follow the pipe part 1 naturally from the inside. The forward pipe section 1 is a round pipe having a circular or elliptical shape (not shown) in the radial direction, but the outer peripheral wall of the forward pipe section 1 is directed in the circumferential direction as shown in FIG. You may form so that it may meander, or you may form in the flat tube which made the long diameter side the pointed shape which becomes thin toward both outer side like FIG.3 (b). In addition, as shown to Fig.4 (a), you may wind so that the outward pipe part 1 may be diameter-reduced sequentially toward the downward direction, and in this case, make the hole 3 for embedding into the shape of a bowl. Can do. The return pipe section 2 is erected on the inner diameter side of the outgoing pipe section 1 so as not to protrude to the outer diameter side, and is easily accommodated in the embedding hole 3 so as to speed up excavation and embedding work. Further, as shown in FIG. 4 (b), all the outgoing pipe sections 1 may be wound so as to have the same diameter.

  FIG. 5 shows an example in which the winding shape of the forward tube portion 1 is a polygonal shape. FIG. 5A shows the forward tube portion 1 having a diameter gradually increasing downward, and FIG. 5B shows the forward tube portion. FIG. 5 (c) shows a case where each of the forward pipe sections 1 is wound so as to have the same diameter so that the diameters of the pipes 1 are gradually reduced downward. In the example shown in the figure, the lengths of the straight tube portions of the forward tube portion 1 are all substantially the same and are square, but may be partially different to have a rectangular shape as shown in FIG. FIG. 6B is a diagram in which the diameter of the forward pipe portion 1 is sequentially increased downward, and FIG. The case where each of the outward pipe sections 1 is wound so as to have the same diameter is shown. In this way, the length of each straight tube portion of the forward tube portion 1 can be set freely, and the number of corners can be increased or decreased to form a triangular shape or a hexagonal shape. FIG. 7 shows an example in which the winding shape of the forward tube portion 1 is an ellipse. FIG. 7A shows that the forward tube portion 1 has a diameter gradually increasing downward, and FIG. FIG. 7C shows a case where each of the outward pipe sections 1 is wound to have the same diameter so that the diameter of the section 1 is sequentially reduced downward. In the case of FIG. 6 and FIG. 7, the embedding hole 3 can be formed into a narrow groove shape that is easy to dig. In addition, each said Example is not limited to a figure example, The number of turns (stage number) of the outward pipe part 1 and a dimension change of a diameter are free, and also the outward pipe part 1 is expanded or contracted entirely or partially toward the downward direction. Is also free.

  FIG. 8 shows another embodiment, which is a pair of resin-made outward pipe sections 1 and 1 that face each other at a predetermined interval and flow while the heating medium descends in a meandering manner, and the heating medium that has come out of the outgoing pipe section 1. And a return pipe section 2 for returning the ground to the ground, and the other construction is the same as that of the above embodiment. 8A, the distance between the pair of forward pipe sections 1, 1 gradually increases downward, and FIG. 8B, the distance between the pair of forward pipe sections 1, 1 gradually decreases downward. As shown in FIG. 8C, the pair of forward pipe sections 1 and 1 are arranged such that the distance between them is the same. In the case of FIG. 8 (a), as shown by the phantom line, the buried soil becomes a mountain shape at the center of the diameter of the forward pipe section 1 during the burying operation, and can naturally follow the forward pipe sections 1 and 1 from the inside. In the case of 8 (b), the embedding hole 3 can be formed into a V-groove shape that is easy to dig, and in the case of FIG. 8C, the embedding hole 3 can be formed into a narrow groove shape that is easy to dig. In addition, increase / decrease in the number of meanders and intervals of the outward pipe part 1 is free. Further, in the illustrated example, the forward pipe section 1 is formed so as to be alternately folded in the reverse direction at the ends of a large number of parallel straight pipe sections so that the internal circulation heat medium is lowered. The length of the tube can be increased or decreased and the number of steps can be changed.

BRIEF DESCRIPTION OF THE DRAWINGS The whole simplified perspective view which shows one Example of this invention. Sectional drawing of an outward pipe part. Sectional drawing of the other shape example of an outward pipe part. The simplified perspective view of the other shape example of an outward pipe part. The simplified perspective view of another example of a shape of an outward pipe part. The simplified perspective view of another example of shape of an outward pipe part. The simplified perspective view of another example of shape of an outward pipe part. The simplified perspective view which shows the other Example of this invention.

Explanation of symbols

1 Outbound pipe section 2 Inbound pipe section

Claims (8)

  A subsurface heat exchanger that adjusts the temperature of a heat medium that is buried in the ground and that flows through the interior by means of underground heat, and a resin-made forward pipe section 1 that flows while the heat medium descends spirally near the ground surface; An underground heat exchanger comprising: a return pipe section 2 for returning the heat medium from the forward pipe section 1 to the ground.   The underground heat exchanger according to claim 1, wherein the forward pipe section 1 is wound so as to be gradually expanded in diameter downward or sequentially reduced in diameter downward.   The underground heat exchanger according to claim 1 or 2, wherein the winding shape of the forward pipe section 1 is round, polygonal, or oval.   A subsurface heat exchanger that adjusts the temperature of a heat medium that is buried in the ground and that flows through the inside by means of underground heat, and is opposed to the ground surface at a predetermined interval and flows while the heat medium descends in a meandering manner. A ground heat exchanger comprising a pair of resin-made forward pipe sections 1 and 1 and a return pipe section 2 for returning the heat medium that has come out of the forward pipe section 1 to the ground.   The underground heat exchanger according to claim 4, wherein the ground heat exchanger is disposed so that a distance between the pair of forward pipe sections 1 and 1 is gradually expanded downward or is gradually decreased downward.   The underground heat exchanger according to claim 1, 2, 3, 4 or 5, wherein the forward pipe section 1 is a flat pipe.   The underground heat exchanger according to claim 6, wherein the long-diameter side of the forward pipe section 1 is pointed.   The underground heat exchanger according to claim 1, 2, 3, 4 or 5, wherein the forward pipe section 1 is a round pipe and an outer peripheral wall thereof is formed in a meandering shape in the circumferential direction.

Images