JPH08338890A - High heat load cooling pipe - Google Patents

Abstract

PURPOSE: To provide a high heat load cooling pipe which has simultaneously the effect of promoting turbulent flow near the cooling pipe wall and of holding bubble nuclei on the wall surface in a high heat load heat removal device for removing heat of high heat load and has high heat transfer performance by arranging circular cooling pipes at the part receiving high heat load. CONSTITUTION: By providing inside of a cooling pipe 3 with a cylindrical coil 8 formed in multiple net with coils 7 wound in reverse directions each other, turbulent flow near the pipe wall is more promoted, the effect of removing bubbles generated from the wall surface, and cooling performance is improved compared with the case of cooling pipe of a single inserted coil. Also, by assembling the coil 7 in net, each coil 7 is supported and therefore, the strength of the coil 7 becomes high and lowering of cooling performance due to deformation of the coil 7 is prevented. Moreover, by fining the intervals of the coils assembled in net and arranging them with contact to the pipe wall, an effect that the contact part between the pipe wall and the coil surface holds bubble nuclei is enhanced, and steam is stably generated from the pipe wall and so high cooling performance is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high heat load heat removal apparatus applied to a plasma facing device such as a diverter used in a nuclear fusion reactor, or a beam dump of a neutral particle beam injection apparatus which is a plasma heating apparatus. Regarding

[0002]

2. Description of the Related Art In future fusion reactor development, 10 (M
The removal of heat from a high heat load device that receives a heat flux of W / m ² or more, for example, a plasma facing device such as a diverter or a beam dump of a neutral particle beam injector is an important issue.

By the way, a high heat load device that receives such a high heat flux is generally composed of a cooling pipe group, and heat is removed by circulating a refrigerant at a high speed. When the refrigerant removes heat from the pipe wall and is heated, and the temperature of the heat receiving surface exceeds the saturation temperature of the refrigerant, boiling starts. The boiling form at this time is nucleate boiling in which bubbles are repeatedly generated and separated from the wall surface. Further, as the heat flux rises, boiling becomes more violent, and finally the film transitions to film boiling in which the tube wall is covered with the vapor phase of the refrigerant and the liquid phase is not supplied to the tube wall.

At this time, the temperature of the pipe wall rises rapidly by 1000 ° C. or more and exceeds the melting point of the material of the pipe wall, so that the cooling pipe melts and fractures. The transition from nucleate boiling to film boiling is called burnout, and the heat flux at that time is called critical heat flux.

As a technique for improving the critical heat flux of a cooling pipe, a heat-removing pipe is constructed by inserting a spiral tape into a right circular pipe-shaped refrigerant pipe, and is removed by using forced convection subcool boiling of water as a refrigerant. Providing heat is suggested. This is to generate a swirling flow in the refrigerant by inserting a spiral tape into the refrigerant pipe.The centrifugal force of the swirling flow removes the bubbles generated from the pipe wall and causes the unheated refrigerant to flow to the pipe wall. It has already been clarified that it has a supply effect, heat transfer is promoted, and the critical heat flux is increased compared to the normal straight flow (Reference: "Heat Transfer Engineering Material Revision 4th Edition", p194, The Japan Society of Mechanical Engineers). , 1986).

Also, in a cooling pipe in which a coil wound in a spiral shape is inserted instead of the spiral tape, the limit heat flux is usually the same due to the effect of promoting turbulent flow near the wall surface of the pipe and removing bubbles generated from the wall surface. It has already been clarified that the flow rate is larger than that of the straight flow (reference: GP Celata et al., Warm).
e und Stoffubertragung, vol.27 (1992), 233. 4 to 6 show the basic structure of such a conventional high heat load heat removal apparatus. As shown in FIGS. 4 to 6, the refrigerant inlet pipe 1 and the refrigerant outlet pipe 2 arranged in parallel with each other at regular intervals are adjacent to each other by a large number of end portions of the cooling pipe 3 having a right circular tube shape as a heat removal pipe. And in multiple steps,
Each is connected for communication. In the illustrated example, the cooling pipe 3
Are stacked in two layers vertically and arranged in parallel at equal intervals. Further, in the configuration example shown in FIG. 4, in order to improve the heat removal performance of the cooling pipe 1, a spiral shape is provided in each cooling pipe 3. Tape 4
Are provided along the axial direction of each cooling pipe 3.

During use, the cooling pipe 3 is arranged in the irradiation area of the neutral particle beam 5 without any gap. The coolant 6 supplied from the coolant inlet pipe 1 to the cooling pipe 3 becomes a swirling flow by the spiral tape 4 and flows in the cooling pipe 3 to cool the heat receiving surface heated by the neutral particle beam 5, It is discharged from the refrigerant outlet pipe 2. At this time, the heat transfer of the refrigerant 6 is promoted by the swirling flow.

[0008]

In the cooling method utilizing the boiling phenomenon, the higher the foaming point density generated from the wall surface and the greater the effect of removing the generated bubbles from the wall surface, the higher the effect of promoting heat transfer. The heat transfer enhancing effect of the cooling pipe having the spiral tape or the spiral coil inserted therein is due to the bubble removing effect by promoting the turbulent flow near the pipe wall.

On the other hand, if the foaming point density on the inner wall surface of the pipe is increased,
The number of bubbles generated from the heat transfer surface is increased, and the cooling performance is improved. Bubbles are repeatedly generated from the bubbling point on the heat transfer surface, but if the bubble radius starts from zero every time, a large degree of wall superheat is required for bubble generation and cooling performance deteriorates. For this reason, it is necessary to hold a certain amount of bubble nuclei at the foaming point on the heat transfer surface, and bubbles that have grown from the bubble nuclei are repeatedly desorbed to maintain a stable boiling state.

A cooling pipe having a spiral coil inserted therein has a great effect of removing generated bubbles, but since the effect of forming and retaining bubble nuclei on the heat transfer surface is the same as that of a normal straight pipe, the cooling capacity of the refrigerant is reduced. Cannot be sufficiently drawn out, and an excessively large refrigerant flow rate is required.

Further, in a cooling pipe having a spiral coil inserted therein, the cooling performance is improved as the wire diameter of the coil is larger and the winding pitch of the coil is smaller, but contrary to this, the flow resistance, that is, the resistance acting on the coil. Power increases.

The coil has sufficient cooling performance when it is held at a predetermined winding pitch. If the flow resistance increases and the coil elastically or plastically deforms in the cooling pipe to increase the winding pitch, the cooling performance increases. It is highly possible that the cooling pipe will burn out. When the coil is fixed on the downstream side, the flow of the refrigerant causes the coil to be compressed at the fixed portion to generate a large resistance, which makes it difficult for the refrigerant to flow, and thus there is a risk of burnout.

The present invention has been made in view of such circumstances, and a first object thereof is to have both an effect of promoting turbulent flow in the vicinity of the tube wall of the cooling tube and an effect of retaining bubble nuclei on the wall surface, which is high. An object is to provide a high heat load cooling pipe having heat transfer performance.

It is a second object of the present invention to provide a high-heat-load heat removal cooling pipe in which stable cooling performance can be obtained in a cooling pipe in which a spiral coil is inserted without the coil being deformed by the flow resistance of the refrigerant.

[0015]

In order to achieve the above-mentioned object, the high heat load cooling pipe according to claim 1 is constructed by assembling a plurality of coils whose winding directions are opposite to each other in a cylindrical shape, along the inner wall surface of the cooling pipe. It is characterized by being arranged as.

According to the second aspect of the present invention, a spiral coil having a wire diameter larger than that of the coil assembled in the cylindrical shape in which the high heat load cooling pipe according to the first aspect is inserted is inserted. It is a feature.

The invention according to claim 3 is characterized in that a spiral tape is inserted inside the coil assembled in a cylindrical shape into which the high heat load cooling pipe according to claim 1 is inserted. The high heat load cooling pipe according to claim 4 is provided in the cooling pipe.
The present invention is characterized in that two or more spiral coils are arranged at equal intervals along the axial direction.

In the high heat load cooling pipe according to the present invention, a spiral coil is arranged in the cooling pipe along the axial direction, and one or more wires are attached to the spiral coil parallel to the axial direction. It is a feature.

[0019]

According to the constitutions of claims 1 to 3,
By inserting a coil in which a number of coils with opposite winding directions are assembled into a cylindrical shape, turbulent flow near the tube wall is promoted and bubbles generated from the wall surface are more promoted than in the case of a cooling tube with one coil inserted. The removal effect is enhanced and the cooling performance is improved. Further, since the strength of the coil is increased by forming the coil in a net shape, it is possible to prevent the cooling performance from being deteriorated due to the deformation of the coil.

Also, by making the spacing between the coils assembled in a mesh shape sufficiently small and closely arranging the coils on the inner wall surface of the tube, the contact portion between the wall surface of the tube and the mesh coil surface has the effect of holding the bubble nucleus, Since the steam is stably generated from the wall, the cooling performance is improved.

Further, in the invention described in claims 2 and 3, a spiral coil or a spiral tape is further provided inside the mesh-shaped coil, and the spiral coil or the spiral tape is generated from the contact portion between the tube wall and the mesh-shaped coil. The effect of removing vapor bubbles from the wall surface is enhanced, and the cooling performance is improved.

In the invention according to claim 4, two or more spiral coils are arranged at equal intervals along the axial direction, so that a single spiral coil is formed,
The winding pitch of each coil can be increased. The flow resistance of the refrigerant acting on the spiral coil is smaller when the winding direction of the coil is as parallel as possible to the axial flow, so that the flow resistance acting on the coil is smaller than that when the spiral coil is composed of one coil. The size of the coil is reduced, and the risk that the coil is deformed and the cooling performance is deteriorated is reduced.

Further, the cooling performance becomes higher as the winding pitch of the coil is smaller, but when one spiral coil having a small winding pitch is inserted by arranging two or more spiral coils at equal intervals. It has the same turbulent flow promoting effect as above, and high cooling performance can be obtained.

In the invention according to claim 5, a spiral coil is arranged in the cooling pipe along the axial direction, and at least one wire-shaped wire is attached to the spiral coil in parallel with the axial direction, and the spiral coil is attached at regular intervals. By fixing the contact portion with the spiral coil by, the strength of the spiral coil can be increased, and the risk that the coil is deformed and the cooling performance is reduced is reduced.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic configuration of an embodiment of the invention described in claim 1. In this embodiment, a large number of coils 7 whose winding directions are opposite to each other are assembled in a net shape to form a cylindrical coil 8 and the cylindrical coil 8 is arranged in the cooling pipe 3.

The effect of removing bubbles generated from the wall surface by promoting turbulent flow in the vicinity of the tube wall by arranging a plurality of coils whose winding directions are opposite to each other in a net shape is more promoted than in the case of a cooling tube in which one coil is inserted. And the cooling performance is improved. In addition, by assembling the coils in a net shape, the strength of the coils is increased because they support each other, so that it is possible to prevent the cooling performance from being deteriorated due to the deformation of the coils.

By inserting a large number of spiral coils into the cooling pipe, the flow resistance of the refrigerant increases, but the strength of the coil is increased by assembling the coils, so that the coil wire diameter can be reduced and its effect is small. . Further, since the effect on the cooling performance becomes greater as the turbulent flow promotion in the cooling pipe is performed as close to the wall surface as possible, the cooling performance is improved as the wire diameter of the coil 7 used for the cylindrical coil 8 is smaller.

Furthermore, the coil 7 assembled in the mesh shape shown in FIG.
Since the space between the pipe wall and the pipe wall is closely attached, the contact area between the pipe wall and the mesh-shaped coil surface has the effect of retaining bubble nuclei, so that stable steam is generated from the pipe wall. However, high cooling performance can be obtained.

In the second aspect of the present invention, a spiral coil is further arranged inside the cylindrical coil 8 shown in FIG.
At this time, the vapor bubbles generated from the contact portion between the tube wall and the cylindrical coil 8 are more effectively separated from the wall surface by the spiral coil disposed inside, and the cooling performance is improved. The coil disposed inside is for the purpose of facilitating bubble separation from the cylindrical coil 8, and the larger the coil wire diameter, the greater the effect, and at least the wire thicker than the coil 7 forming the cylindrical coil 8. It is necessary to use a coil of diameter.

Further, the invention of claim 3 is one in which a spiral tape is disposed inside the cylindrical coil as a mechanism for promoting bubble separation from the cylindrical coil, and the effect of this embodiment is as described above. Is the same as.

FIG. 2 shows an embodiment of the invention described in claim 4. The present embodiment is characterized in that two or more spiral coils are arranged at equal intervals along the axial direction.
In the embodiment shown in (2), the two spiral coils 9a and 9b are arranged at equal intervals along the axial direction.

By arranging the two spiral coils at equal intervals along the axial direction, the winding pitch of each coil can be increased as compared with the case where one spiral coil is formed. . Even if the winding pitch of one coil is doubled, the turbulent flow of the refrigerant flow in the vicinity of the heat receiving surface is promoted by the effect of the two coils, and the effect of bubble separation from the pipe wall is increased. Since the mixing of the separated bubbles and the subicle liquid is promoted, high heat removal performance can be obtained.

Since the flow resistance of the refrigerant acting on the spiral coil is smaller when the winding direction of the coil is as parallel as possible to the axial flow, it works on the coil more than when the spiral coil is composed of one coil. The flow resistance is reduced, and there is no risk that the coil will deform and the cooling performance will decrease.

Further, the cooling performance becomes higher as the coil winding pitch becomes smaller. However, by disposing two or more spiral coils at equal intervals, it is possible to insert one spiral cosule having a small winding pitch. Has a similar turbulence promoting effect,
High cooling performance can be obtained.

FIG. 3 shows an embodiment of the invention described in claim 3, in which a spiral coil 7 is arranged in the cooling pipe along the axial direction, and two spiral coils are arranged in parallel with the spiral coil in the axial direction. Wire
10 was attached, and the contact portion with the spiral coil was fixed at regular intervals. The wire 10 can increase the strength of the spiral coil and reduce the risk that the coil is deformed and the cooling performance is deteriorated.

[0036]

According to the present invention as set forth in claims 1 to 3, a cooling pipe having one coil inserted therein is formed by inserting a coil in which a plurality of coils having opposite winding directions are assembled into a cylindrical shape. In some cases, turbulent flow near the pipe wall is promoted,
The effect of removing bubbles generated from the wall surface is enhanced, and the cooling performance is improved. Further, since the strength of the coil is increased by forming the coil in a net shape, it is possible to prevent the cooling performance from being deteriorated due to the deformation of the coil.

Further, by making the intervals of the coils assembled in a mesh shape sufficiently small and closely disposing the coils on the inner wall surface of the tube, the contact portion between the wall surface of the tube and the mesh surface of the coil has an effect of holding bubble nuclei. Since the steam is stably generated from the wall, the cooling performance is improved.

According to the second and third aspects of the present invention, a mechanism for removing vapor bubbles generated from the contact portion between the pipe wall and the mesh-shaped coil from the wall surface is provided inside the mesh-shaped coil. As a result, the effect of removing bubbles is enhanced and the cooling performance is improved.

In the invention according to claim 4, two or more spiral coils are arranged at equal intervals along the axial direction, so that the spiral coil is constituted by one coil.
The winding pitch of each coil can be increased. The flow resistance of the refrigerant acting on the spiral coil is smaller when the winding direction of the coil is as parallel as possible to the axial flow, so that the flow resistance acting on the coil is smaller than that when the spiral coil is composed of one coil. The size of the coil is reduced, and the risk that the coil is deformed and the cooling performance is deteriorated is reduced.

Further, the cooling performance becomes higher as the winding pitch of the coil is smaller, but when one spiral coil having a small winding pitch is inserted by arranging two or more spiral coils at equal intervals. It has the same turbulent flow promoting effect as above, and high cooling performance can be obtained.

According to the invention of claim 5, a spiral coil is arranged along the axial direction in the cooling pipe, and at least one wire-shaped wire is attached to the spiral coil parallel to the axial direction, and the spiral coil is spirally arranged at regular intervals. By fixing the contact part with the coil,
The strength of the spiral coil can be increased, and there is less risk that the coil will deform and cooling performance will deteriorate.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment corresponding to claim 1 of the present invention.

FIG. 2 is a configuration diagram showing an embodiment corresponding to claim 4 of the present invention.

FIG. 3 is a configuration diagram showing an embodiment corresponding to claim 5 of the present invention.

FIG. 4 is a front view showing the basic configuration of a conventional high heat load heat removal device.

5 is a top view of FIG.

FIG. 6 is a side view of FIG. 4;

[Explanation of Codes] 1 ... Refrigerant inlet pipe 2 ... Refrigerant outlet pipe 3 ... Cooling pipe 4 ... Spiral tape 5 ... Neutral particle beam 6 ... Refrigerant 7 ... Spiral coil 8 ... Cylindrical coil 9 ... Spiral coil 10 ... wire

Claims (5)

[Claims] 1. A cooling pipe in which a circular tubular cooling pipe is arranged in a portion that receives a high heat load, and a spiral coil is arranged in the cooling pipe along an axial direction, and a plurality of coils having mutually opposite winding directions are provided. A high heat load cooling pipe characterized by being assembled in a cylindrical shape and arranged along the inner wall surface in the cooling pipe. 2. A cooling pipe, in which a circular cooling pipe is arranged at a portion subjected to a high heat load, and a spiral coil is arranged along the axial direction in the cooling pipe, a plurality of coils having mutually opposite winding directions are provided. A high heat load cooling pipe, characterized in that it is assembled in a cylindrical shape, and further, a spiral coil having a wire diameter larger than that of the coil is inserted inside the cylindrically assembled coil. 3. A cooling pipe, in which a circular cooling pipe is arranged in a portion which receives a high heat load, and a spiral coil is arranged along the axial direction in the cooling pipe, a plurality of coils having mutually opposite winding directions are provided. A high heat load cooling tube characterized by being assembled in a cylindrical shape and further having a spiral tape inserted inside a coil assembled in a cylindrical shape. 4. A cooling pipe in which a circular tubular cooling pipe is arranged at a portion subjected to a high heat load, and a spiral coil is arranged along the axial direction in the cooling pipe, and two or more spiral coils are axially arranged. A high heat load cooling pipe, wherein the cooling pipes are arranged in the cooling pipe at equal intervals. 5. A cooling pipe in which a circular cooling pipe is arranged in a portion that receives a high heat load, and a spiral coil is arranged in the cooling pipe along the axial direction, and at least in parallel to the spiral coil in the axial direction. A high heat load cooling tube with a single wire-shaped wire attached.