Freezing pipe and soil freezing method

Abstract

To provide a freezing pipe and a soil freezing method for efficiently freezing soil.SOLUTION: A freezing pipe comprises a flexible channel plate portion including a plurality of internal flow paths aligned in the width direction, and a pair of flexible heat transfer plate portions located on both sides of the channel plate portion in the width direction. A width of each of the heat transfer plate portions is at least one time the width of an area occupied by the plurality of internal flow paths of the channel plate portion.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present disclosure relates to a freezing pipe used for freezing soil and a method for freezing soil. [Background technology]

[0002] For example, a construction method is known in which soil is frozen when carrying out civil engineering work. In this construction method, for example, a refrigerant is supplied to a freezing pipe attached to a structure such as a tunnel lining segment to freeze the soil (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6752062 Summary of the Invention [Problem to be solved by the invention]

[0004] Many structures to which freezing pipes are attached are made of concrete. Since concrete structures have a relatively low thermal conductivity, it takes a relatively long time for the soil to freeze. Therefore, it is desirable to shorten the time it takes for the soil to freeze.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a freezing pipe and a soil freezing method for efficiently freezing soil. [Means for solving the problem]

[0006] (1) A freezing tube according to at least one embodiment of the present disclosure includes: a flexible channel plate portion including a plurality of internal flow paths aligned in a width direction; a pair of flexible heat transfer plate portions located on both sides of the channel plate portion in the width direction; Equipped with The width of each of the heat transfer plate portions is at least one time the width of the region of the channel plate portion occupied by the plurality of internal flow paths.

[0007] (2) A soil freezing method according to at least one embodiment of the present disclosure, A step of placing the freezing pipe of the configuration (1) above on the surface of the soil to be frozen; freezing the soil by supplying a heat medium to the freezing pipe; Equipped with. [Effects of the Invention]

[0008] At least one embodiment of the present disclosure allows for efficient soil freezing. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating the overall configuration of a soil freezing device as an example of a refrigeration cycle device including a freezing pipe according to some embodiments. [Figure 2A] FIG. 2 is a diagram showing an example of a cross section of a freezing pipe. [Figure 2B] FIG. 10 is a diagram showing another example of a cross section of a freezing pipe. [Figure 3] 3 is a cross-sectional view taken along the line III-III in FIG. 1, illustrating the case where the freezing tube shown in FIG. 2A is used. [Figure 4A] FIG. 10 is a diagram showing a model for simulating soil freezing using a freezing pipe without a heat transfer plate portion. [Figure 4B] FIG. 4B is a contour diagram showing the temperature distribution, which is a simulation result using the model of FIG. 4A. [Figure 5A] FIG. 10 is a diagram showing a model for simulating soil freezing using a freezing pipe having a heat transfer plate portion thinner than the thickness of the channel plate portion. [Figure 5B] FIG. 5B is a contour diagram showing the temperature distribution, which is a simulation result using the model of FIG. 5A. [Figure 6A]FIG. 10 is a diagram showing a model for simulating soil freezing using a freezing pipe having a heat transfer plate portion with the same thickness as the channel plate portion. [Figure 6B] FIG. 6B is a contour diagram showing the temperature distribution, which is a simulation result using the model of FIG. 6A. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0011] FIG. 1 is a diagram showing the overall configuration of a soil freezing device as an example of a refrigeration cycle device including a freezing pipe according to some embodiments. In some embodiments, the soil freezing device 1 includes a refrigerator 5 having a primary refrigerant circulation system 3 and a secondary refrigerant circulation system 10 connected to the primary refrigerant circulation system 3 via a heat exchanger 7.

[0012] In a secondary refrigerant circulation system 10 according to some embodiments, a receiver tank 11 capable of receiving refrigerant from the heat exchanger 7, a pump 13 for circulating the refrigerant in the receiver tank 11 through the secondary refrigerant circulation system, and a plurality of soil freezing pipes 40 (hereinafter also simply referred to as freezing pipes 40) for freezing the soil 30 are provided in a refrigerant circulation path 21 of the secondary refrigerant circulation system 10. In a secondary refrigerant circulation system 10 according to some embodiments, a liquid header 17 for distributing liquid-phase refrigerant to the plurality of freezing pipes 40 and a gas header 19 for collecting gas-phase refrigerant from the plurality of freezing pipes 40 are provided in the refrigerant circulation path 21. In the secondary refrigerant circulation system 10 according to some embodiments, the refrigerant (secondary refrigerant) is, for example, a CO2 refrigerant.

[0013] In some embodiments of the secondary refrigerant circulation system 10, the freezing pipe 40 is attached to a structure 25, such as a tunnel lining segment. In the secondary refrigerant circulation system 10 according to some embodiments, the surface of the freezing pipe 40 opposite to the structure 25 (the upper surface in the figure) is covered with a heat insulating material 27.

[0014] In the soil freezing device 1 configured in this manner, the secondary refrigerant cooled by the refrigerator 5 via the heat exchanger 7 is supplied to the liquid header 17 by the pump 13, and then supplied from the liquid header 17 to multiple freezing pipes 40. When the secondary refrigerant supplied to the freezing pipes 40 evaporates within the freezing pipes 40, it absorbs heat from the surrounding soil 30 via the structure 25 to which the freezing pipes 40 are attached. As a result, the soil 30 around the freezing pipes 40 freezes.

[0015] The vapor-phase secondary refrigerant evaporated in the freezing pipes 40 is collected in the gas header 19 and returned to the receiver tank 11. The gas-phase secondary refrigerant in the receiver tank is cooled and liquefied in the heat exchanger 7 and returns to the receiver tank 11 as a liquid-phase secondary refrigerant. In the example shown in FIG. 1, the freezing pipe 40 is configured so that the secondary refrigerant flows from one side to the other side in the longitudinal direction of the freezing pipe 40, but the freezing pipe 40 may also be configured so that the secondary refrigerant flows from one side to the other side in the longitudinal direction of the freezing pipe 40 and then returns to one side again.

[0016] FIG. 2A is a diagram showing an example of a cross section of the freezing pipe 40. As shown in FIG. FIG. 2B is a diagram showing another example of a cross section of the freezing pipe 40. As shown in FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1, illustrating the case where the freezing pipe 40 shown in FIG. 2A is used. In some embodiments of the soil freezing device 1, the freezing pipe 40 includes a flexible channel plate portion 43 including a plurality of internal flow paths 41 arranged in the width direction, and a pair of flexible heat transfer plate portions 45 located on either side of the channel plate portion 43 in the width direction, as shown in Figures 2A and 2B, for example.

[0017] In the freezing pipe 40 according to some embodiments, the channel plate portion 43 is a part having a flat shape in which a plurality of internal flow paths 41 are formed. In the freezing tube 40 according to some embodiments, the pair of heat transfer plate portions 45 have a solid structure.

[0018] In some embodiments of the freezing tube 40, the channel plate portion 43 and the pair of heat transfer plate portions 45 may be formed integrally, or the channel plate portion 43 and the pair of heat transfer plate portions 45 may be formed as separate members but connected to each other to allow relatively efficient heat transfer. In the freezing pipe 40 according to some embodiments, the inlet and outlet for the refrigerant of each of the plurality of internal flow paths 41 may be provided at one longitudinal end of the channel plate portion 43. That is, in the freezing pipe 40 according to some embodiments, the channel plate portion 43 may be provided with an internal flow path 41 serving as an outward path for the refrigerant and an internal flow path 41 serving as a return path for the refrigerant. This allows the channel plate portion 43 to be space-saving. In addition, in some embodiments of the freezing pipe 40, the refrigerant inlet of each of the multiple internal flow paths 41 may be provided at one longitudinal end of the channel plate portion 43, and the refrigerant outlet may be provided at the other longitudinal end of the channel plate portion 43.

[0019] In the freezing pipe 40 shown in FIG. 2A, the thickness t1 of the pair of heat transfer plate portions 45 is equal to the thickness t2 of the channel plate portion 43. In the freezing pipe 40 shown in FIG. 2B, the thickness t1 of the pair of heat transfer plate portions 45 is greater than the thickness t2 of the channel plate portion 43.

[0020] FIG. 4A is a diagram showing a model of a simulation of freezing of soil 30 by a freezing pipe 40X that does not have a heat transfer plate portion 45. For convenience of illustration, in FIG. 4A, the thickness of the freezing tube 40X is drawn to be thicker than the thickness of the freezing tube 40X used in the simulation. FIG. 4B is a contour diagram showing the temperature distribution, which is a simulation result using the model of FIG. 4A. FIG. 5A is a diagram showing a model of a simulation of freezing of soil 30 by freezing pipe 40Y having heat transfer plate portion 45 thinner than the thickness of channel plate portion 43. For convenience of illustration, in FIG. 5A, the thickness of the frozen pipe 40Y is drawn to be thicker than the thickness of the frozen pipe 40Y used in the simulation. FIG. 5B is a contour diagram showing the temperature distribution, which is a simulation result using the model of FIG. 5A. FIG. 6A is a diagram showing a model for simulating freezing of soil 30 by a freezing pipe 40A having a heat transfer plate portion 45 with the same thickness as that of a channel plate portion 43. As shown in FIG. For convenience of illustration, in FIG. 6A, the thickness of the freezing pipe 40A is drawn to be thicker than the thickness of the freezing pipe 40A used in the simulation. FIG. 6B is a contour diagram showing the temperature distribution, which is a simulation result using the model of FIG. 6A. In the contour diagrams of Figures 4B, 5B, and 6B, the darker the black, the lower the temperature. Also, in the contour diagrams of Figures 4B, 5B, and 6B, the concentration, i.e., the temperature distribution, changes stepwise for convenience of illustration, but in reality, the concentration, i.e., the temperature distribution, changes gradually.

[0021] In the simulation models shown in Figures 4A, 5A, and 5B, the height, i.e., thickness dimension, of freezing tubes 40X, 40Y, and 40A is 5 mm, the width is 64 mm, and the length is 1000 mm. In the simulation model shown in FIGS. 5A and 5B, the width direction dimension of the heat transfer plate portions 45 of the freezing pipe 40Y and the freezing pipe 40A is 64 mm for each of the pair of heat transfer plate portions 45. In the simulation model shown in FIG. 5A, the thickness of the heat transfer plate portion 45 of the freezing pipe 40Y is 1 mm. In the simulation model shown in FIG. 6A, the thickness of the heat transfer plate portion 45 of the freezing pipe 40A is 5 mm.

[0022] In the simulation models shown in FIGS. 4A, 5A, and 5B, it is assumed that CO2 refrigerant at −40° C. flows through the internal flow paths 41 of the freezing pipes 40X, 40Y, and 40A. In the simulation models shown in FIGS. 4A, 5A, and 5B, structure 25T is made of reinforced concrete and contains 1.66% iron by weight. In the simulation models shown in FIGS. 4A, 5A, and 5B, soil (ground) 30T is assumed to be earth with a moisture content of 60%.

[0023] 4B, 5B, and 6B, the temperature of the soil 30 is lower over a wider range when the heat transfer plate portion 45 is present than when the heat transfer plate portion 45 is not present. Also, as is clear from comparing Fig. 5B and Fig. 6B, the temperature of the soil 30 is lower over a wider range when the heat transfer plate portion 45 is thicker.

[0024] After careful consideration, the inventors found that in the freezing tube 40, the width of each heat transfer plate portion 45, i.e., the widthwise dimension, should be at least one time the width of the area occupied by the multiple internal flow paths of the channel plate portion 43 (the width of the channel plate portion 43 shown in Figures 2A and 2B). Therefore, in the soil freezing device 1 according to some embodiments, the width of each heat transfer plate portion 45 is set to be equal to or greater than the width of the region occupied by the plurality of internal flow paths of the channel plate portion 43. According to the freezing pipes 40 of the soil freezing device 1 of some embodiments, the pair of heat transfer plate sections 45 are cooled by cold energy from the secondary refrigerant, which is a heat medium, flowing through the channel plate section 43. Therefore, compared to when only the channel plate section 43 is used, a wider range can be cooled in the width direction of the channel plate section 43, and the soil 30 can be frozen efficiently. Furthermore, the number of freezing pipes 40 arranged in the soil freezing device 1 of some embodiments can be reduced, which also contributes to energy savings.

[0025] In the soil freezing device 1 according to some embodiments, the pair of heat transfer plate portions 45 may have a solid structure. After careful consideration by the inventors, it was found that a pair of heat transfer plate sections 45 with a relatively large heat capacity results in better heat transfer to the soil 30 when the soil 30, which is the object of freezing, is frozen by the freezing pipe 40. By making the pair of heat transfer plate portions 45 a solid structure, the heat capacity of the pair of heat transfer plate portions 45 can be increased compared to when the pair of heat transfer plate portions 45 have a hollow structure, thereby improving heat transfer to the soil 30 to be frozen.

[0026] In the soil freezing device 1 according to some embodiments, the thickness t1 of the pair of heat transfer plate portions 45 may be equal to or greater than the thickness t1 of the channel plate portion 43. As described above, the heat transfer to the soil 30 when the soil 30 to be frozen by the freezing pipe 40 is improved when the heat capacity of the pair of heat transfer plate portions 45 is relatively large. According to some embodiments of the soil freezing device 1, the heat capacity of the pair of heat transfer plate portions 45 can be increased compared to when the thickness t1 of the pair of heat transfer plate portions 45 is less than the thickness t2 of the channel plate portion, thereby improving heat transfer to the soil 30 to be frozen.

[0027] As shown in Fig. 3, the soil freezing device 1 according to some embodiments may be provided with a heat insulating material 27 that covers one surface in the thickness direction of the channel plate portion 43 and the pair of heat transfer plate portions 45, i.e., the upper surfaces shown in Figs. 1 and 3. In the example shown in Fig. 3, the heat insulating material 27 covers the entire upper surfaces of the channel plate portion 43 and the pair of heat transfer plate portions 45. The heat insulating material 27 may be attached with an adhesive to the upper surface of the freezing pipe 40. The heat insulating material 27 may also be connected to bolt holes (not shown) provided in the heat transfer plate portion 45 with bolts (not shown). According to the soil freezing device 1 of some embodiments, the soil 30 to be frozen can be cooled more efficiently.

[0028] (Method of soil freezing using soil freezing device 1) A description will be given of a soil freezing method using the soil freezing device 1 according to some embodiments. The soil freezing method using the soil freezing device 1 according to some embodiments includes step S10 of placing the freezing pipe 40 on the surface of the soil 30 to be frozen (hereinafter referred to as placing step S10), and step S20 of freezing the soil 30 by supplying a heat medium to the freezing pipe 40 (hereinafter referred to as freezing step S20).

[0029] (Placement step S10) The placing step S10 is a step of placing the freezing pipe 40 on the surface of the soil to be frozen. In the placing step S10, the freezing pipe 40 is placed on the surface of the soil 30 to be frozen, more specifically, on a structure 25 installed in the soil 30, such as a tunnel lining segment. In the placing step S10, a plurality of freezing pipes 40 are placed in the number required to freeze the entire area of ​​the soil to be frozen. As described above, the channel plate portion 43 and the heat transfer plate portion 45 of the freezing pipe 40 are flexible, so the freezing pipe 40 can be effectively installed even on curved surfaces such as the inner wall of a tunnel. Then, in the placement step S10, a heat insulating material is provided on the top surface of the freezing pipe 40. In the placing step S10, the freezing pipe 40 is placed, and then the freezing pipe 40 is connected to the liquid header 17 and the gas header 19.

[0030] (Freezing step S20) The freezing step S20 is a step in which the soil 30 is frozen by supplying the secondary refrigerant from the liquid header 17 to the plurality of freezing pipes 40 arranged in the arranging step S10. In the freezing step S20, the soil 30 can be frozen by supplying the secondary refrigerant from the liquid header 17 to the plurality of freezing pipes 40 arranged in the arranging step S10.

[0031] According to the soil freezing method using the soil freezing device 1 according to some embodiments, the pair of heat transfer plate units 45 are cooled by the heat medium flowing through the channel plate unit 43. Therefore, compared to when only the channel plate unit 43 is used, a wider area of ​​the soil 30 can be cooled in the width direction of the channel plate unit 43.

[0032] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0033] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A freezing tube 40 according to at least one embodiment of the present disclosure includes a flexible channel plate portion 43 including a plurality of internal flow paths 41 aligned in the width direction, and a pair of flexible heat transfer plate portions 45 located on both sides in the width direction of the channel plate portion 43. The width of each heat transfer plate portion 45 is at least one time the width of the region of the channel plate portion 43 occupied by the plurality of internal flow paths 41.

[0034] According to the configuration (1) above, the pair of heat transfer plate sections 45 are cooled by cold energy from the heat medium (secondary refrigerant) flowing through the channel plate section 43. Therefore, compared to when only the channel plate section 43 is used, a wider range can be cooled in the width direction of the channel plate section 43, and the soil 30 can be frozen efficiently. Furthermore, according to the configuration (1) above, the number of freezing pipes 40 can be reduced, which contributes to energy saving. According to the above configuration (1), the channel plate portion 43 and the pair of heat transfer plate portions 45 are flexible, so that the freezing pipe 40 can be effectively installed even on a curved surface such as the inner wall of a mine shaft.

[0035] (2) In some embodiments, in the configuration of (1) above, the pair of heat transfer plate portions 45 may have a solid structure.

[0036] According to the configuration (2) above, the heat capacity of the pair of heat transfer plate sections 45 can be increased compared to when the pair of heat transfer plate sections 45 have a hollow structure, thereby improving heat transfer to the object to be frozen (soil 30).

[0037] (3) In some embodiments, in the configuration of (1) or (2) above, the thickness t1 of the pair of heat transfer plate portions 45 may be equal to or greater than the thickness t2 of the channel plate portion 43.

[0038] According to the above configuration (3), the heat capacity of the pair of heat transfer plate portions 45 can be increased compared to when the thickness t1 of the pair of heat transfer plate portions 45 is less than the thickness t2 of the channel plate portion 43, thereby improving heat transfer to the object to be frozen (soil 30).

[0039] (4) In some embodiments, in any of the configurations (1) to (3) above, it is preferable to provide a heat insulating material 27 covering one side of the thickness direction of the channel plate portion 43 and the pair of heat transfer plate portions 45, among the channel plate portion 43 and the pair of heat transfer plate portions 45.

[0040] According to the above configuration (4), the object to be frozen (the soil 30) can be cooled more efficiently.

[0041] (5) A soil freezing method according to at least one embodiment of the present disclosure includes step S10 of placing a freezing pipe 40 having any of the configurations (1) to (4) above on the surface of the soil 30 to be frozen, and step S20 of freezing the soil 30 by supplying a heat medium (secondary refrigerant) to the freezing pipe 40.

[0042] According to the method (5) above, the pair of heat transfer plate members 45 are cooled by the heat medium (secondary refrigerant) flowing through the channel plate member 43. Therefore, compared to when only the channel plate member 43 is used, a wider range of the soil 30 can be cooled in the width direction of the channel plate member 43. [Explanation of symbols]

[0043] 1. Soil freezing device 3 Primary refrigerant circulation system 5. Freezer 7 Heat exchanger 10 Secondary refrigerant circulation system 11 Receiver tank 17 Liquid header 19 Gas Header 21 Refrigerant circuit 25, 25T structure 27 Heat insulation material 30, 30T soil (ground) 40, 40A, 40X, 40Y Soil Freezing Pipe (Freezing Pipe) 41 Internal flow path 43 Channel plate section 45 Pair of heat transfer plates

Claims

1. a flexible channel plate portion including a plurality of internal flow paths aligned in a width direction; a pair of flexible heat transfer plate portions located on both sides of the channel plate portion in the width direction; Equipped with The width of each of the heat transfer plate portions is equal to or greater than the width of the region occupied by the plurality of internal flow paths of the channel plate portion. cryotube.

2. The pair of heat transfer plate portions have a solid structure. The freezing tube of claim 1 .

3. The thickness of the pair of heat transfer plate portions is equal to or greater than the thickness of the channel plate portion. The freezing tube according to claim 1 or 2.

4. a heat insulating material covering one surface in a thickness direction of the channel plate portion and the pair of heat transfer plate portions, The freezing tube according to claim 1 or 2.

5. a step of placing the freezing pipe according to claim 1 or 2 on the surface of soil to be frozen; freezing the soil by supplying a heat medium to the freezing pipe; Equipped with Soil freezing methods.

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