Ebullition cooling device

Abstract

To provide an ebullition cooling device comprising a heat transfer tube that can take measures against dry regions that do not contribute to cooling with a simple configuration, and can suppress increase in pressure loss.SOLUTION: An ebullition cooling device comprises a heat transfer tube having a long flow path through which a refrigerant flows. The heat transfer tube has: a tube body that defines the flow path and includes a heat transfer surface that receives heat from a heating element; and a partition wall provided in the flow path. The partition wall extends in a longitudinal direction of the flow path, and divides the flow path into two or more spaces.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a boiling cooling device. [Background technology]

[0002] 2. Description of the Related Art A boiling cooling device that cools a heat-generating body by utilizing latent heat generated by boiling of a refrigerant is known. As an example of the boiling cooling device, a cooling device having a cylindrical heat transfer tube is known.

[0003] Cooling devices with heat transfer tubes have a much smaller circulation flow rate than general water-cooled cooling devices, with a small Reynolds number of between 100 and 3000. This results in laminar flow inside the heat transfer tube. Therefore, when the refrigerant boils inside the heat transfer tube, the vapor of the two-phase refrigerant tends to accumulate in the upper part of the heat transfer tube, and the liquid phase refrigerant tends to accumulate in the lower part of the heat transfer tube.

[0004] The heat transfer tube described in Patent Document 1 has a twisted partition wall inside to diffuse the liquid-phase refrigerant accumulated in the lower part. For example, the partition wall has a shape twisted at least one turn to the end of the heat transfer tube. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 524593 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the conventional twisted partition wall, depending on the twist angle, there is a risk that a region where steam accumulates inside the heat transfer tube continues to occur. As a result, there is a risk that a large dry region that does not contribute to cooling is formed on the heat transfer surface, which is the inner wall surface of the heat transfer tube. Therefore, the cooling efficiency of the conventional heat transfer tube may not be different from that of a simple tube without a partition wall. In addition, it is very difficult to manufacture a partition wall with a twisted shape. Furthermore, there is a risk that the pressure loss increases in the partition wall with a twisted shape.

[0007] In view of the above, there is a demand for a boiling cooling device equipped with a heat transfer tube that has a simple configuration, can take measures against dry areas that do not contribute to cooling, and can suppress an increase in pressure loss. [Means for solving the problem]

[0008] In order to solve the above problems, a boil cooling device according to a preferred embodiment of the present disclosure includes a heat transfer tube having a long flow path through which a refrigerant flows, the heat transfer tube having a tube body that constitutes the flow path and includes a heat transfer surface that receives heat from a heating element, and a partition wall provided in the flow path, the partition wall extending in the longitudinal direction of the flow path and dividing the flow path into two or more spaces. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a cooling system including a boil cooling device according to a first embodiment. [Diagram 2] 2 is a simplified cross-sectional view of a motor on which the boiling cooling device of FIG. 1 is mounted. [Diagram 3] FIG. 4 is a vertical cross-sectional view of a heat transfer tube of a comparative example. [Figure 4] FIG. 4 is a cross-sectional view of a heat transfer tube of a comparative example. [Diagram 5] FIG. 2 is a vertical cross-sectional view of the heat transfer tube of the first embodiment. [Figure 6] FIG. 2 is a cross-sectional view of the heat transfer tube of the first embodiment. [Figure 7] FIG. 6 is a vertical sectional view of a heat transfer tube according to a second embodiment. [Figure 8]FIG. 6 is a cross-sectional view of a heat transfer tube according to a second embodiment. [Figure 9] FIG. 11 is a cross-sectional view of a heat transfer tube according to a modified example. [Figure 10] FIG. 11 is a vertical sectional view of a heat transfer tube according to a third embodiment. [Figure 11] FIG. 11 is a cross-sectional view of a heat transfer tube according to a third embodiment. [Figure 12] FIG. 11 is a cross-sectional view of a heat transfer tube according to a modified example. [Figure 13] FIG. 11 is a cross-sectional view of a heat transfer tube according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. In the drawings, the dimensions and scale of each part are appropriately different from the actual ones, and some parts are shown diagrammatically to facilitate understanding. In addition, the scope of the present disclosure is not limited to these forms unless otherwise specified in the following description to limit the present disclosure. In addition, "equal" means that it is sufficient to be substantially equal, and includes manufacturing errors, etc.

[0011] 1. First embodiment 1-1. Cooling system 100 equipped with boiling cooling device 1 Fig. 1 is a schematic diagram of a cooling system 100 including a boil cooling device 1 according to a first embodiment. Fig. 2 is a simplified cross-sectional view of a motor 9 on which the boil cooling device 1 of Fig. 1 is mounted.

[0012] For convenience, the following description will be given using the Z axis as appropriate. One direction along the Z axis is the Z1 direction, and the opposite direction to the Z1 direction is the Z2 direction. Typically, the Z axis is a vertical line, the Z1 direction corresponds to the vertical upward direction, and the Z2 direction corresponds to the vertical downward direction. The direction of the Z axis in real space is determined according to the installation posture of the boiling cooling device 1. The Z axis may be inclined within a range of 45° or less with respect to the vertical line. In the following, the term "upper" simply refers to a position in a direction along the vertical line, and includes both the vertical upward direction and the vertical diagonally upward direction as a concept. Similarly, the term "lower" simply refers to a position in a direction along the vertical line, and includes both the vertical downward direction and the vertical diagonally downward direction as a concept.

[0013] 1 includes a boiling cooling device 1, a heat exchanger 7, and a liquid delivery pump 8. The boiling cooling device 1 is mounted on, for example, a motor 9. The boiling cooling device 1 may be mounted on something other than the motor 9, and may be mounted on other equipment or electronic components that generate heat when driven or energized, etc., as long as cooling is required.

[0014] As shown in FIG. 2, the motor 9 has a stator 91, a rotor 92, and a shaft 93. The stator 91 is a cylindrical stator. The stator 91 generates a force for rotating the rotor 92. The stator 91 is provided with a winding 911. For example, the stator 91 is made of an iron core, and the winding 911 is made of copper wire. The winding 911 is an example of a "heat generating element." The boiling cooling device 1 is disposed on the stator 91.

[0015] The rotor 92 is a motor configured to be rotatable around a central axis of rotation O9. The rotor 92 is made of, for example, a silicon steel plate. The rotor 92 is provided with, for example, a permanent magnet 921. The shaft 93 is a long output shaft extending in the front and rear directions of the page. The shaft 93 penetrates the center of the rotor 92 and is made of, for example, iron.

[0016] In such a motor 9, energy is imparted by a rotating magnetic field generated by windings 911 of a stator 91, and a rotor 92 rotates around a central axis of rotation O9 as indicated by an arrow A0.

[0017] The configuration of the motor 9 is merely an example, and the boil cooling device 1 may be provided on a motor having a different configuration.

[0018] The boiling cooling device 1 cools the winding 911, which serves as a "heat generating element," by utilizing heat transport due to latent heat accompanying the boiling of the refrigerant. The boiling cooling device 1 has two heat transport pipe sections 10 through which the refrigerant flows. The two heat transport pipe sections 10 are provided symmetrically in FIG. 2. One heat transport pipe section 10 is located on the right side in FIG. 2, and the other heat transport pipe section 10 is located on the left side in FIG. 2. The two heat transport pipe sections 10 are embedded in the stator 91, for example, but do not have to be embedded in the stator 91.

[0019] As shown in Fig. 1, the heat transport pipe section 10 has an inlet 101 through which the refrigerant flows in, and an outlet 102 through which the refrigerant flows out. The heat transport pipe section 10 includes a plurality of heat transfer pipes 3 and a plurality of connecting pipes 2. Each heat transfer pipe 3 is a long, straight circular pipe. Each connecting pipe 2 connects two adjacent heat transfer pipes 3. The heat transfer pipes 3 and the connecting pipes 2 form the heat transport pipe section 10 into a long pipe.

[0020] 2, the heat transfer tubes 3 are spaced apart from one another and aligned along the circumferential direction of the stator 91. In the example of FIG. 2, each of the two heat transport tube sections 10 has nine heat transfer tubes 3. In the example of FIG. 2, the inlet 101 of the heat transport tube section 10 is located at the lowest part of the heat transport tube section 10, and the outlet 102 is located at the highest part of the heat transport tube section 10.

[0021] Each of the plurality of heat transfer tubes 3 and the plurality of connecting tubes 2 is preferably made of a material having excellent thermal conductivity, for example, a metal material such as copper, aluminum, or an alloy of any of these.

[0022] In the boil cooling device 1, the refrigerant flows in from the inlet 101, as shown by the arrow A1 in Fig. 1. The refrigerant then flows through the heat transport pipe section 10, as shown by the arrow A2 in Fig. 2. During this flow, the liquid-phase refrigerant, which is a liquid refrigerant, receives heat from the winding 911, which is a "heat generating element," and vaporizes to generate a gas-phase refrigerant. Then, the gas-phase refrigerant flows out from the outlet 102, as shown by the arrow A3 in Fig. 1.

[0023] The refrigerant is a medium that is liquid at room temperature, and includes, for example, water such as pure water, or a mixture of water and alcohol. The alcohol is, for example, ethanol or methanol. The type of refrigerant may be a type other than the above types. In addition, it is preferable that a surfactant is added to the refrigerant. The surfactant may be a nonionic surfactant or an ionic surfactant such as an anionic surfactant or a cationic surfactant. Specific examples of the surfactant include a fluorine-based surfactant, a silicone-based surfactant, and a hydrocarbon-based surfactant. When the refrigerant is water, it is preferable to use a hydrocarbon-based surfactant that has excellent solubility.

[0024] The heat exchanger 7 shown in FIG. 1 is connected to the boiling cooling device 1 via a vapor pipe 61. The heat exchanger 7 cools the gas-phase refrigerant supplied from the boiling cooling device 1 via the vapor pipe 61 by heat exchange with an external fluid. The external fluid is not particularly limited and may be a liquid or a gas. The heat exchanger 7 changes the gas-phase refrigerant into a liquid-phase refrigerant.

[0025] The liquid feed pump 8 adjusts the flow rate of the liquid-phase refrigerant supplied to the boil cooling device 1 via a liquid pipe 62. The structure of the liquid feed pump 8 is not particularly limited, and may be, for example, a plunger pump or a diaphragm pump. The liquid feed pump 8 is connected to the boil cooling device 1 via a liquid pipe 63.

[0026] 1-2. Comparative example heat transfer tube 3x Fig. 3 is a longitudinal sectional view of a heat transfer tube 3x of a comparative example. Fig. 4 is a transverse sectional view of a heat transfer tube 3x of a comparative example. The heat transfer tube 3x of the comparative example shown in Figs. 3 and 4 has a simple cylindrical shape. The inner wall surface of the heat transfer tube 3x is a heat transfer surface 30x that receives heat from a heating element. A refrigerant flows in the heat transfer tube 3x in the direction of an arrow A2.

[0027] When the refrigerant near the heat transfer surface 30x is overheated to a temperature equal to or higher than the boiling point, a plurality of bubbles B are generated on the heat transfer surface 30x. The generated bubbles B are buoyant and move vertically upward from the heat transfer surface 30x. Therefore, the bubbles B tend to accumulate in the vertically upward portion of the heat transfer tube 3x, and the bubbles B tend to merge with each other in the vertically upward portion. As a result, large merged bubbles B0 are formed in the vertically upward portion of the heat transfer surface 30x. When the heat transfer surface 30x is covered with the large merged bubbles B0, a large dry region Sx is formed on the heat transfer surface 30x.

[0028] The dry region Sx is a region of the heat transfer surface 30x that does not contact the refrigerant and does not contribute to heat transfer. Since the dry region Sx does not contribute to heat transfer, the boiling heat transfer performance decreases as the dry region Sx becomes larger. The heat transfer tube 3 of this embodiment is configured to suppress the expansion of the dry region Sx and suppress the decrease in cooling performance.

[0029] 1-3. Heat transfer tube 3 of this embodiment FIG. 5 is a longitudinal sectional view of the heat transfer tube 3 of the first embodiment. FIG. 6 is a transverse sectional view of the heat transfer tube 3 of the first embodiment. As shown in FIG. 5 and FIG. 6, the heat transfer tube 3 of this embodiment has a tube body 31 and a partition wall 32. The tube body 31 is cylindrical. The inner wall surface of the heat transfer tube 3 is a heat transfer surface 30. The heat transfer surface 30 is cylindrical. The heat transfer surface 30 receives heat from the winding 911, which is a heating element. The heat transfer surface 30 constitutes a long flow path S1 through which the refrigerant flows. The flow path S1 is long and cylindrical. In this embodiment, the longitudinal direction of the flow path S1 intersects with the vertical direction and is parallel to the horizontal direction. In the flow path S1, the refrigerant flows in the direction of the arrow A2.

[0030] 5 and 6, the partition wall 32 is provided inside the heat transfer tube 3, i.e., in the flow path S1. The partition wall 32 extends in the longitudinal direction of the flow path S1 and divides the flow path S1 into two or more spaces. In this embodiment, the flow path S1 is divided by the partition wall 32 into three spaces S11, S12, and S13. Each of the spaces S11, S12, and S13 is a space that extends in the longitudinal direction of the flow path S1.

[0031] The partition wall 32 has three walls 321, 322, and 323. Each of the three walls 321, 322, and 323 is a flat plate extending in the longitudinal direction of the flow path S1. Each of the three walls 321, 322, and 323 extends inward from the heat transfer surface 30 and is connected to each other. The connection portion of the three walls 321, 322, and 323 overlaps with the center line O1 along the longitudinal direction of the flow path S1. The wall portion 321 and the wall portion 322 are located vertically below the center line O1. The connection portion of the wall portion 321 and the wall portion 322 is located at the vertically uppermost position of the wall portion 321 and the wall portion 322. The angle between the wall portion 321 and the wall portion 323 is 180° or less. The wall portion 321 and the wall portion 322 intersect with the vertical direction and the horizontal direction. Furthermore, wall portion 323 is located vertically above the connection portion of the three walls 321, 322, and 323. Wall portion 323 is disposed along the vertical direction.

[0032] A space S11 is defined by the wall portion 321, each wall portion 322, and a portion of the heat transfer surface 30. A space S12 is defined by the wall portion 321, each wall portion 323, and a portion of the heat transfer surface 30. A space S13 is defined by the wall portion 322, each wall portion 323, and a portion of the heat transfer surface 30. The volumes of the spaces S11, S12, and S13 are equal to one another.

[0033] The walls 321, 322, and 323 may be formed integrally with the pipe body 31, or may be formed separately and connected with a bonding material, etc. Each of the walls 321, 322, and 323 may be formed integrally with the pipe body 31, or may be formed separately and connected with a bonding material, etc.

[0034] As described above, the partition wall 32 extends in the longitudinal direction of the flow path S1 and divides the flow path S1 into three spaces S11, S12, and S13, which are "two or more spaces." Therefore, by providing the partition wall 32, the amount of bubbles B that come into contact with the heat transfer surface 30 can be reduced compared to a case in which the partition wall 32 is not provided. Therefore, the dry area Sx on the heat transfer surface 30 can be reduced. This makes it possible to improve the cooling performance.

[0035] By providing the partition wall 32, the bubbles B generated vertically below the partition wall 32 are held by the partition wall 32. Specifically, when the bubbles B generated vertically below the walls 321 and 322, i.e., in the space S11, leave the heat transfer surface 30 and rise vertically upward due to buoyancy, they come into contact with the walls 321 and 322 and stay there. Therefore, the bubbles B that stay at the walls 321 and 322 do not move vertically upward from the walls 321 and 322. Therefore, the bubbles B that stay at the walls 321 and 322 do not come into contact with the heat transfer surface 30. That is, although the bubbles B in the space S11 form a combined bubble B0, they do not contribute to the formation of the dry region Sx on the heat transfer surface 30. In this way, by providing the walls 321 and 322, the amount of the bubbles B that come into contact with the vertically upper portion of the heat transfer surface 30 can be reduced. This reduces the amount of bubbles B that contribute to the formation of the dry region Sx, thereby preventing the combined bubbles B0 from becoming larger, and thus preventing the dry region Sx from expanding.

[0036] Furthermore, the air bubbles B in the spaces S12 and S13 rise due to buoyancy and come into contact with the heat transfer surface 30. As a result, the air bubbles B contribute to the formation of the dry region Sx. However, in the spaces S12 and S13, the amount of the air bubbles B that contribute to the formation of the dry region Sx is reduced by the volume of the space S13 from the flow path S1. Because the volume of the space S11 is 1 / 3 of the volume of the flow path S1, the amount of the air bubbles B that contribute to the formation of the dry region Sx is reduced by this reduction in volume. Therefore, the amount of the air bubbles B that come into contact with the heat transfer surface 30 can be reduced.

[0037] Furthermore, the partition walls 32 extend in the longitudinal direction of the flow path S1. The partition walls 32 do not need to have a twisted shape as in the past. Thus, the configuration of the partition walls 32 is simple. Therefore, according to this embodiment, a measure for the dry region Sx that does not contribute to cooling can be taken with a simple configuration. Furthermore, since the partition walls 32 extend in the longitudinal direction of the flow path S1, the flow of the refrigerant in the flow path S1 is prevented from being blocked by the partition walls 32. Therefore, an increase in pressure loss in the flow path S1 due to the provision of the partition walls 32 can be prevented.

[0038] As described above, the partition wall 32 divides the flow path S1 into three spaces S11, S12, and S13 having the same volume. By making the volumes of the three spaces S11, S12, and S13 equal to each other, it is possible to suppress an increase in pressure loss in the flow path S1 compared to when the volumes are different. Note that the volumes of the three spaces S11, S12, and S13 may be different from each other.

[0039] The partition wall 32 has a flat plate shape extending in the longitudinal direction. Specifically, each of the multiple wall portions 321, 322, and 323 of the partition wall 32 has a flat plate shape extending in the longitudinal direction. The flat plate shape makes it easier to form the partition wall 32 and can suppress an increase in pressure loss compared to when the partition wall 32 has a curved shape.

[0040] As described above, each of the multiple wall portions 321, 322, and 323 extends from the heat transfer surface 30 toward the inside of the flow path S1 when viewed in the longitudinal direction, and is connected to one another. The connection portion of the multiple wall portions 321, 322, and 323 is located on the center line O1. Since the partition wall 32 has such a configuration, the flow path S1 can be divided into multiple spaces S11, S12, and S13 with a simple configuration. Furthermore, it is easy to make the volumes of the three spaces S11, S12, and S13 equal. Therefore, it is easy to suppress an increase in pressure loss in the flow path S1.

[0041] One wall portion 323 of the multiple wall portions 321, 322, and 323 is disposed along the vertical direction. Furthermore, the wall portion 323 is disposed vertically above the connection portion of the walls 321, 322, and 323. By providing such wall portion 323, a meniscus M is formed by surface tension at the connection portion between the heat transfer surface 30 and the wall portion 323, compared to a case where the wall portion 323 is not provided. Therefore, the expansion of the dry region Sx is suppressed. Therefore, the deterioration of the cooling performance can be suppressed.

[0042] As described above, the remaining wall portions 321 and 323 among the multiple wall portions 321, 322, and 323 are disposed vertically below the connection portion of the wall portions 321, 322, and 323. Therefore, the air bubbles B in the space S11 tend to remain at the wall portions 321 and 322 and are unlikely to come into contact with the heat transfer surface 30. The air bubbles B that remain at the wall portions 321 and 322 do not move vertically above the wall portions 321 and 322 and do not contribute to the formation of the dry region Sx. Therefore, the expansion of the dry region Sx on the heat transfer surface 30 can be suppressed.

[0043] The material of the partition wall 32 is not particularly limited, but is preferably a material having a lower thermal conductivity than the tube body 31 .

[0044] Moreover, the number of the "wall portions" is preferably 3 or less. In this embodiment, the partition wall 32 has three walls 321, 322, and 323. By having the number of the "wall portions" be 3 or less, an increase in pressure loss is more easily suppressed than when the number is 4 or more.

[0045] According to the heat transfer tube 3 of the boil cooling device 1 described above, with a simple configuration, it is possible to take measures against the dry region that does not contribute to cooling, and also to suppress an increase in pressure loss.

[0046] 2. Second embodiment A second embodiment will be described below. In the following exemplary embodiments, for elements whose actions and functions are similar to those of the first embodiment, the reference numerals used in the description of the first embodiment will be used and detailed descriptions of each will be omitted as appropriate.

[0047] Fig. 7 is a longitudinal sectional view of a heat transfer tube 3A of the second embodiment. Fig. 8 is a transverse sectional view of the heat transfer tube 3A of the second embodiment. The heat transfer tube 3A shown in Figs. 7 and 8 has a partition wall 33. The flow path S1 is divided into two spaces S14 and S15 by the partition wall 33. Each of the spaces S14 and S15 is a space extending in the longitudinal direction of the flow path S1.

[0048] The partition wall 33 has a flat plate shape and is arranged along a horizontal direction intersecting with the vertical direction. From another perspective, the partition wall 33 is arranged along the arrow A2, which is the direction in which the refrigerant flows. The partition wall 33 is connected to the heat transfer surface 30. As shown in FIG. 8, when viewed in the longitudinal direction of the flow path S1, the left and right sides of the partition wall 33 are each connected to the heat transfer surface 30. The partition wall 33 overlaps with the center line O1 of the flow path S1.

[0049] A space S14 is defined by the partition wall 33 and the lower parts of the heat transfer surfaces 30. A space S15 is defined by the partition wall 33 and the upper parts of the heat transfer surfaces 30. The volumes of the spaces S14 and S15 are equal to each other.

[0050] The partition wall 33 in this embodiment extends in the longitudinal direction of the flow path S1 and divides the flow path S1 into two spaces S14 and S15, which are "two or more spaces." Therefore, by providing the partition wall 33, the amount of bubbles B that come into contact with the heat transfer surface 30 can be reduced compared to when the partition wall 33 is not provided. Therefore, the dry area Sx on the heat transfer surface 30 can be reduced. This makes it possible to improve the cooling performance.

[0051] Moreover, the partition 33 is disposed along a horizontal direction intersecting the vertical direction. Therefore, the bubbles B generated below the partition 33 are held by the partition 33. Therefore, the bubbles B that remain at the partition 33 do not move vertically upward from the partition 33. Therefore, although the bubbles B that remain at the partition 33 form a combined bubble B0, they are unlikely to contribute to the formation of a large dry region Sx. Since the volume of the space S14 is half the volume of the flow path S1, the amount of the bubbles B that contribute to the formation of the dry region Sx is reduced by the amount of this reduction in volume. Therefore, by providing the partition 33, the amount of the bubbles B that contribute to the formation of the dry region Sx can be reduced compared to the case where the partition 33 is not provided. Therefore, the combined bubbles B0 can be prevented from becoming large, and the expansion of the dry region Sx can be prevented.

[0052] Moreover, the configuration of the partition wall 33 is simpler than the configuration of the partition wall 32 of the first embodiment. According to this embodiment, it is possible to suppress an increase in pressure loss in the flow path S1 compared to the first embodiment.

[0053] Fig. 9 is a longitudinal sectional view of a heat transfer tube 3Aa of a modified example. A partition wall 33a of the heat transfer tube 3Aa of Fig. 9 has a flat plate portion 331 along the horizontal direction and two bent portions 332 and 333. The flat plate portion 331 overlaps the center line O1. The two bent portions 332 and 333 are located on both sides of the flat plate portion 331 when viewed in the longitudinal direction and are located vertically above the flat plate portion 331. The two bent portions 332 and 333 are formed by bending the partition wall 33a along the longitudinal direction. The two bent portions 332 and 333 are closer to the heat transfer surface 30 than the center line O1 of the flow path S1.

[0054] Since the partition wall 33a has the bent portions 332 and 333, the expansion of the dry region Sx can be suppressed compared to the partition wall 33 in Fig. 8. At the connection portion between each of the bent portions 332 and 333 and the heat transfer surface 30, a meniscus M is formed by surface tension. This suppresses the expansion of the dry region Sx. As a result, the deterioration of the cooling performance can be suppressed.

[0055] 3. Third embodiment A third embodiment will be described. In the following exemplary embodiments, for elements whose actions and functions are similar to those of the first embodiment, the reference numerals used in the description of the first embodiment will be used and detailed descriptions of each will be omitted as appropriate.

[0056] Fig. 10 is a longitudinal sectional view of a heat transfer tube 3B of the third embodiment. Fig. 11 is a transverse sectional view of the heat transfer tube 3B of the third embodiment. The heat transfer tube 3B shown in Figs. 10 and 11 has a partition wall 34. The flow path S1 is divided into three spaces S16, S17, and S18 by the partition wall 34. Each of the spaces S16, S17, and S18 is a space extending in the longitudinal direction of the flow path S1.

[0057] The partition wall 34 has three walls 341, 342, and 343. Each of the three walls 341, 342, and 343 is a flat plate extending in the longitudinal direction of the flow path S1. Each of the three walls 341, 342, and 343 extends inward from the heat transfer surface 30 and is connected to one another.

[0058] The connection portion of the three wall portions 341, 342, and 343 does not overlap with the center line O1 of the flow path S1. The connection portion is located vertically above the center line O1. The wall portions 342 and 343 are arranged along the horizontal direction. The wall portion 341 is arranged along the vertical direction. The angle between the wall portion 341 and the wall portion 342 is 90°. The angle between the wall portion 341 and the wall portion 343 is 90°.

[0059] Space S16 is defined by wall portion 341, each wall portion 342, and a portion of heat transfer surface 30. Space S17 is defined by wall portion 341, each wall portion 343, and a portion of heat transfer surface 30. Space S18 is defined by wall portion 342, each wall portion 343, and a portion of heat transfer surface 30. Spaces S16, S17, and S18 have the same volume.

[0060] The partition wall 34 in this embodiment extends in the longitudinal direction of the flow path S1 and divides the flow path S1 into three spaces S16, S17, and S18, which are "two or more spaces." Therefore, by providing the partition wall 34, the amount of bubbles B that contact the heat transfer surface 30 can be reduced compared to a case where the partition wall 34 is not provided. Therefore, the dry area Sx on the heat transfer surface 30 can be reduced. Therefore, the cooling performance can be improved.

[0061] In this embodiment, the air bubbles B in the spaces S16 and S17 are less likely to contribute to the formation of the dry region Sx. The volume of the spaces S16 and S17 is ⅔ of the volume of the flow path S1, and the amount of the air bubbles B that contribute to the formation of the dry region Sx is reduced by the amount of the reduction in volume. Therefore, the expansion of the dry region Sx can be suppressed compared to the first embodiment.

[0062] The volume of the space S18 may be smaller than the volumes of the spaces S16 and S17. In this case, the amount of the air bubbles B in the space S18 can be further reduced.

[0063] Fig. 12 is a cross-sectional view of a modified heat transfer tube 3Ba. As shown in Fig. 12, the partition wall 34a of the heat transfer tube 3Ba has a wall portion 342a and a wall portion 343a instead of the wall portion 342 and the wall portion 343. The wall portion 342a and the wall portion 343a cross each other in the horizontal direction and the vertical direction. All of the wall portion 341, the wall portion 342a, and the wall portion 343a are located vertically below the connection portion of the wall portion 341, the wall portion 342a, and the wall portion 343a. The connection portion is located vertically above the center line O1.

[0064] All of the wall portion 341, the wall portion 342a, and the wall portion 343a are located vertically below the connection portion of the wall portion 341, the wall portion 342a, and the wall portion 343a. Therefore, in the heat transfer tube 3Ba, the combined bubbles B0 are less likely to contact the heat transfer surface 30 in the spaces S16 and S17 compared to the heat transfer tube 3B of FIG. 11. In addition, in the heat transfer tube 3Ba, as in the heat transfer tube 3B of FIG. 11, the volume of the spaces S16 and S17 is 2 / 3 of the volume of the flow path S1, so the amount of bubbles B that contribute to the formation of the dry region Sx is reduced by the amount of this reduction in volume. For this reason, according to the heat transfer tube 3a of FIG. 12, the dry region Sx on the heat transfer surface 30 can be particularly small while reducing the pressure loss. Therefore, it is possible to improve the cooling performance.

[0065] 4. Fourth embodiment A fourth embodiment will be described. In the following exemplary embodiments, the elements having the same actions and functions as those in the first embodiment will be designated by the same reference numerals as those in the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0066] Fig. 13 is a cross-sectional view of a heat transfer tube 3C of the fourth embodiment. The heat transfer tube 3C shown in Fig. 13 has a partition wall 35. The flow path S1 is divided into four spaces S01, S02, S03, and S04 by the partition wall 35. Each of the spaces S01, S02, S03, and S04 is a space extending in the longitudinal direction of the flow path S1.

[0067] The partition wall 35 has four wall portions 351, 352, 353, and 354. Each of the four wall portions 351, 352, 353, and 354 is a flat plate extending in the longitudinal direction of the flow path S1. Each of the four wall portions 351, 352, 353, and 354 extends inward from the heat transfer surface 30 and is connected to each other. Each of the four wall portions 351, 352, 353, and 354 intersects with the vertical direction and the horizontal direction.

[0068] A space S01 is formed by the wall portion 351, each wall portion 352, and a portion of the heat transfer surface 30. A space S02 is formed by the wall portion 351, each wall portion 353, and a portion of the heat transfer surface 30. A space S03 is formed by the wall portion 352, each wall portion 354, and a portion of the heat transfer surface 30. A space S04 is formed by the wall portion 353, each wall portion 354, and a portion of the heat transfer surface 30. The volumes of the spaces S01, S02, S03, and S04 are equal to each other.

[0069] The partition 35 has a simple structure. Also, the air bubbles B in the space S01 are unlikely to contribute to the formation of the dry region Sx. Because the volume of the space S01 is 1 / 4 of the volume of the flow path S1, the amount of the air bubbles B that contribute to the formation of the dry region Sx is reduced by the amount of the reduction in the volume. Therefore, the expansion of the dry region Sx can be suppressed.

[0070] Furthermore, a meniscus M is formed by surface tension at the connection between each of the walls 353 and 354 and the heat transfer surface 30. Therefore, in the spaces S02 and S03, the expansion of the dry region Sx on the heat transfer surface 30 is suppressed compared to the space S04. Therefore, the deterioration of the cooling performance can be suppressed.

[0071] 5. Variations The above-described embodiments may be modified in various ways, for example as described below. In addition, the modifications may be combined as appropriate.

[0072] The partition wall may be formed, for example, only by a flat plate member extending along the vertical direction. Even in this case, the meniscus is formed, so that the expansion of the dry region Sx can be suppressed compared to the case where the partition wall is not provided.

[0073] The "heat transfer tube" may have a shape other than a cylinder, and may be an ellipse or a polygon, for example.

[0074] Although the present disclosure has been described above based on the illustrated embodiments, the present disclosure is not limited thereto. In addition, the configurations of the components of the present disclosure can be replaced with any configuration that exhibits the same functions as those of the above-described embodiments, and any configuration can be added. [Explanation of symbols]

[0075] 1...boiling cooling device, 2...connecting tube, 3...heat transfer tube, 3A...heat transfer tube, 3Aa...heat transfer tube, 3B...heat transfer tube, 3Ba...heat transfer tube, 3C...heat transfer tube, 3x...heat transfer tube, 7...heat exchanger, 8...liquid transfer pump, 9...motor, 10...heat transport tube section, 30...heat transfer surface, 30x...heat transfer surface, 31...tube body, 32...partition wall, 33...partition wall, 33a...partition wall, 34...partition wall, 34a...partition wall, 35...partition wall, 61...steam tube, 62...liquid tube, 63...liquid tube, 91...stator, 92...rotor, 93...shaft, 100...cooling system, 101...inlet, 102...outlet, 321...wall, 322...wall, 3 23...wall portion, 332...bent portion, 331...flat portion, 341...wall portion, 342...wall portion, 342a:wall portion, 343...wall portion, 343a:wall portion, 351...wall portion, 352...wall portion, 353...wall portion, 354...wall portion, 911...winding, 921...permanent magnet, B...bubble, B0...combined bubbles, M...meniscus, O1...center line, O9...rotation center axis, S01...space, S02...space, S03...space, S04...space, S1...flow path, S11...space, S12...space, S13...space, S14...space, S15...space, S16...space, S17...space, S18...space, Sx...dry area.

Claims

1. A heat transfer tube having a long flow path through which a refrigerant flows, The heat transfer tube is A pipe body that configures the flow path and includes a heat transfer surface that receives heat from a heating element; A partition wall is provided in the flow path, The partition wall extends in a longitudinal direction of the flow channel and divides the flow channel into two or more spaces. A boiling cooling device characterized by:

2. The partition wall has a flat plate shape extending in the longitudinal direction. The boiling cooling device according to claim 1.

3. The longitudinal direction intersects with the vertical direction, The partition walls are arranged along a direction intersecting the vertical direction. The boiling cooling device according to claim 2.

4. The partition wall has a bent portion bent along the longitudinal direction, The bent portion is closer to the heat transfer surface than a center line along the longitudinal direction of the flow path. The boiling cooling device according to claim 3.

5. The partition divides the flow path into two or more spaces having equal volumes. The boiling cooling device according to claim 1.

6. The partition wall has a plurality of wall portions, Each of the plurality of wall portions extends from the heat transfer surface toward the inside of the flow path when viewed in the longitudinal direction and is connected to each other. The boiling cooling device according to claim 1.

7. The number of the walls is three or less. The boiling cooling device according to claim 6.

8. The longitudinal direction intersects with the vertical direction, One wall portion of the plurality of wall portions is disposed along the vertical direction, The one wall portion is disposed vertically above a connection portion of the plurality of wall portions. The boiling cooling device according to claim 6.

9. The remaining wall portions of the plurality of wall portions are disposed vertically below the connection portion of the plurality of wall portions. The boiling cooling device according to claim 8.

10. The longitudinal direction intersects with the vertical direction, The plurality of wall portions are disposed vertically below a connection portion of the plurality of wall portions. The boiling cooling device according to claim 6.

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