JPH04356689A - Heat radiation pipe for natural convection type heat exchanger and fabrication thereof - Google Patents

Abstract

PURPOSE:To provide a heat radiation pipe and a method of fabrication thereof, the heat radiation pipe being used for a natural convection type heat exchanger, the heat radiation pipe further having a satisfactory heat exchange efficiency and being strong and permitting a longitudinal external heat transfer fin to be formed even with metals not suited to protrusion molding other than an aluminum alloy. CONSTITUTION:A heat radiation pipe is divided radially into several parts. Each divided longitudinal member 1 includes heat radiation pieces 11 protruded radially and integrally therewith on opposite side ends of a pipewall 9 serving as a primary heat transfer surface. The heat radiation pieces 11 are both fixedly mounted to an adjacent longitudinal member 1. Hereby, the adjacent heat radiation pieces 11 are coupled. With this coupling, an external heat transfer fin 4 is formed by collecting and joining those heat radiation pieces around the primary heat transfer pipe 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat radiation tube for a natural convection heat exchanger in which the flow between an internal fluid and an external fluid to be heat exchanged is driven only by the difference in temperature or specific gravity of the fluids.

0002

2. Description of the Related Art This type of heat dissipation tube is used, for example, by being vertically attached to the outside of a casing surrounding a heat dissipating body and connected to the casing at both upper and lower ends. The flow of the fluid will be explained with reference to FIG. 8, which illustrates an example.

[0003] This figure shows a gas-gas type heat exchanger in a transformer.
2 is installed inside the casing 30, and the heat sink P is installed vertically outside the casing 30. However, inside the casing 30, an upward current of insulating gas is generated due to the heat radiation of the transformer 32, so that the heat sink P is insulated. Gas flows in from the upper end port 34,
In the heat dissipation pipe P, it descends due to cooling by outside air, and the lower end port 36
into the casing 30 and is thus automatically circulated due to temperature changes. In addition, on the outside of the heat dissipation tube P, the air is heated, thereby generating an upward air current, and the convection phenomenon of this air also promotes heat exchange.

[0004] Conventional heat dissipation tubes of this type include:
External heat transfer fins are provided protrudingly. There are two types of external heat transfer fins: vertical and horizontal. In the case of the vertical type, extruded aluminum is used (for example, Utility Model No. 63-13427
No. 4), external heat transfer fins are integrally formed in the longitudinal direction by extrusion. Further, in the case of a horizontal type, the external heat transfer fins are formed in a flange shape and are arranged in upper and lower stages in a flange-like shape made of iron alloy, which is not suitable for extrusion molding. In the case of an extruded profile, the internal heat transfer fins as well as the external heat transfer fins are also formed vertically.

[0005]

[Problems to be Solved by the Invention] As mentioned above, in a heat dissipation tube that utilizes natural convection of fluid, there must be no obstruction to convection on the outside, so the external heat transfer fins are horizontal in the form of flanges. It is preferable to have a vertical shape. However, conventionally, vertical external heat transfer fins have not been provided except for those made of extruded aluminum sections due to molding considerations.

[0006] When the heat dissipation tube is made of aluminum, the heat exchange performance is good due to its thermal conductivity, but if the fluid on the heat dissipation side is natural outside air, it may be difficult to use in areas prone to salt damage, such as near the coast. There are restrictions that prevent it from being used. Also, even if it is installed in a normal location, joints made of metals with different ionization tendencies are used, and there is a problem that the connection parts will corrode. This is desirable.

[0007] In view of the above-mentioned circumstances, this invention
Even if it is a metal other than aluminum alloy that is not suitable for extrusion molding,
The object of the present invention is to provide a heat dissipation tube for a natural convection heat exchanger that can form vertical external heat transfer fins, has good heat exchange efficiency, and is durable, and a method for manufacturing the same.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention divides a heat dissipation tube into several parts in the diametrical direction, and each of the divided vertical members has two parts on both sides of the tube wall, which serve as primary heat transfer surfaces. A heat dissipation piece that serves as an external secondary heat transfer surface is integrally provided at the end to protrude in the radial direction, and is connected to an adjacent vertical member by aligning and fixing the heat dissipation pieces, and this connection radiates heat around the primary heat transfer tube. A heat dissipation tube for a natural convection heat exchanger is constructed, which is characterized by vertical external heat transfer fins formed by combining pieces.

In addition, internal heat transfer fins may be provided between adjacent vertical members so as to protrude toward the center of the primary heat transfer tube, and the internal heat transfer fins may be inserted between the vertical members and fixed together.

[0010] Furthermore, each internal heat transfer fin is made of a plate material,
The plate material may be sandwiched between adjacent external heat transfer fins.

Furthermore, the internal heat transfer fins may be divided into upper and lower steps, and may be bent or twisted stepwise from side to side.

Alternatively, the internal heat transfer fins, which are divided into upper and lower stages, may pass through the center of the tube and be sandwiched between opposing vertical members and fixed integrally.

[0013] Further, in the present invention, a plurality of vertical members are formed by longitudinally elongated heat transfer plates, and when forming the vertical members, a primary heat transfer surface forming a part of a certain circle at the center of the width is formed by press molding. By forming an arc-shaped tube wall and bending both ends in the radial direction of the circle, heat dissipation pieces that serve as secondary heat transfer surfaces are provided protruding from both ends, and the heat dissipation pieces of adjacent vertical members are aligned. A method for manufacturing a heat dissipation tube for a natural convection heat exchanger is constructed, which is characterized by sequentially connecting vertical members by fixing them together.

[0014]

[Function] Regarding the use of the above heat dissipation tube, the internal fluid descends inside the primary heat transfer tube, and the heat received from the fluid in the primary heat transfer tube is directly discharged to the external fluid, as well as the heat dissipation piece integrated with it. conducted directly without connection to the external fluid. Further, since the external heat transfer fins are vertical and do not impede the convection of the external fluid, heat exchange is performed efficiently.

Since the external heat transfer fin is a combination of two heat dissipating pieces that are integrated with the tube wall, it acts as a strong rib and resists internal pressure, so it is effective for heat exchange. The tube walls can be made thinner to increase efficiency.

Regarding manufacturing, the vertical members can be easily assembled by forming the same shape from metal plates such as iron alloys which are not suitable for extrusion molding, and welding them one after another.

[0017] When the internal heat transfer fins are provided in a protruding manner, the heat receiving area increases accordingly, so that the heat exchange efficiency becomes even better.

[0018] Furthermore, if the tube is sandwiched between external heat transfer fins, the effect of preventing deformation and breakage of the tube due to internal pressure will be increased.

[0019] Furthermore, if the internal heat transfer fins are bent or twisted stepwise to the left and right, this will prevent the development of a fluid film within the pipe, resulting in good heat transfer efficiency. Become.

Furthermore, by attaching the internal heat transfer fins to each of the vertical fins divided into several parts in stages, the internal pressure strength can be dramatically improved.

[0021]

[Embodiment] FIGS. 1 to 3 show a first embodiment, in which a heat dissipation pipe P includes ten vertical members 1, 1...
It consists of a combination of ten plate members 3, 3, .

Next, the structure will be specifically explained according to the manufacturing method. For the vertical member 1 and the plate material 3, band-shaped heat transfer plates made of iron alloy are used, respectively. As for the vertical member 1, as shown in FIG. 2, the center of the width is used as a tube wall 9 which becomes a primary heat transfer surface, and by bending both ends to widen outward, both ends become secondary heat transfer surfaces. heat dissipation piece 11,
11 is formed. However, this heat dissipation piece 11 is not formed at both the upper and lower ends (FIG. 3).

The tube wall 9 is curved into an arc shape following the circular shape of the primary heat exchanger tube 2. However, at the protruding portion of the heat dissipating piece 11, the width is made narrower by the thickness of the plate material 3, and at the other upper and lower ends, the width is formed by dividing the primary heat exchanger tube 2 into 10 equal parts.

The heat dissipating piece 11 is formed in a radial direction with respect to the circle of the primary heat exchanger tube 2, and has a stepped portion 13 that increases outwardly at the center of the protruding width in order to sandwich the plate material 3 in half from the base end. , the step is formed to be half the thickness of the plate material 3.

When assembling, the adjacent vertical members 1,
1, the plate material 3 is sandwiched between the heat dissipating pieces 11, 11, and resistance welding is performed in this state to join the three pieces together. While repeating this process, the entire assembly is assembled, and the seams 15 at both upper and lower ends are sealed by welding.

The assembly is now complete, and a large number of pipe walls 9, 9
A primary heat exchanger tube 2 is formed by connecting the , .
External heat transfer fins 4 are formed in the radial direction, and the plate material 3
is sandwiched and fixed between the two heat dissipating pieces 11, 11, and a part of it is directed toward the center of the primary heat exchanger tube 2 by the internal heat transfer fin 6.
,6,... Further, both upper and lower ends serve as connection ports 19, 19 with the joint 17 (see FIG. 8).

FIG. 4 shows a second embodiment, in which the heat dissipation tube P has thin auxiliary internal heat transfer fins 12, 12 welded to both sides of the protruding base end of each internal heat transfer fin 6. The auxiliary internal heat transfer fins 12, 12 are bent and protruded so as to be separated from each other in the protruding direction, and are intermittent at different levels vertically so as to be able to cross each other.

The other points are the same as those of the above embodiment, and by providing the auxiliary internal heat transfer fins 12 in this manner, the internal heat transfer efficiency is further improved.

FIGS. 5 and 6 show a third embodiment. This heat sink P is basically the same as the first embodiment, and each vertical member is divided into eight equal parts. 1,1,...
A channel-shaped member 21 is provided at the center of the width of the outer surface of each tube wall 9.
By welding, a pair of auxiliary external heat transfer fins 14, 14 are respectively provided in a protruding manner.

FIG. 7 shows a fourth embodiment, in which the heat dissipation tube P is formed with auxiliary internal heat transfer fins 12 as in the second embodiment, but in addition, internal heat transfer fins 12 are formed. By making vertical cuts in the tip of the heat fin 6,
The left tip fin 6a, the straight tip fin 6b, and the right tip fin 6c are formed in a stepwise manner. Twisting each of the tip fins further inhibits the development of a boundary layer of the internal fluid. The same holds true even if the auxiliary internal heat transfer fins 12 are twisted.

[0031]

[Effects of the Invention] As explained above, the present invention has succeeded in forming vertical external heat transfer fins even from metals such as iron alloys that are not suitable for extrusion molding, and according to the heat dissipation tube, The heat received by the primary heat transfer tube from the internal fluid is
It is directly conducted to the heat dissipation piece that is integrated with it without any connection, and due to its heat conduction efficiency, heat dissipation from the external heat transfer fins is very good, and this also goes hand in hand with the fact that the external heat transfer fins do not interfere with the convection of the external fluid. Therefore, heat exchange is performed efficiently. Furthermore, since the external heat transfer fins effectively function as ribs, it is possible to prevent the tube from being deformed or damaged due to internal pressure, and it is expected that the heat exchange efficiency will be improved by forming the tube wall thinner.

Regarding manufacturing, it is possible to easily assemble the vertical members by forming them into the same shape and welding them one after another.
It is suitable for mass production and can be provided at low cost.

[0033] When the internal heat transfer fins are provided protrudingly, the heat receiving area increases accordingly, and the harmonization of the internal and external secondary heat transfer areas further improves the heat exchange efficiency.

If the internal heat transfer fins are sandwiched between the external heat transfer fins, the heat exchange efficiency will be further improved by integrating the inner and outer secondary heat transfer fins, and the deformation of the tube due to internal pressure will be improved. , the damage prevention effect becomes greater.

[0035] Furthermore, if the internal heat transfer fins are bent or twisted stepwise from side to side, this will cause turbulence in the fluid within the pipe and prevent the development of a boundary layer or film. , the heat conduction efficiency is very good.

Furthermore, by attaching the internal heat transfer fins to each of the vertical fins divided into several parts in stages, the internal pressure strength can be dramatically improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a heat dissipation tube showing a first embodiment of the present invention.

FIG. 2 is a perspective explanatory view of the embodiment showing an assembly procedure.

FIG. 3 is a front view of the upper end of the embodiment.

FIG. 4 is a cross-sectional front view of the second embodiment.

FIG. 5 is a cross-sectional front view of the third embodiment.

FIG. 6 is a front view of the upper end of the embodiment.

FIG. 7 is a cross-sectional view of the fourth embodiment.

FIG. 8 is an explanatory diagram showing how the heat dissipation tube of the present invention is used.

[Explanation of symbols] P Heat radiation tube for natural convection heat exchanger 1 Vertical member 2 Primary heat exchanger tube 3 Plate material 4 External heat transfer fins 6 Internal heat transfer fins 9 Pipe wall 11 Heat dissipation piece

Claims (6)

[Claims] Claim 1: A heat dissipation tube is divided into several parts in the diametrical direction, and each divided vertical member is provided with heat dissipation pieces that serve as external secondary heat transfer surfaces at both ends of the tube wall that serves as the primary heat transfer surface in the radial direction. They are integrally protruded and connected to adjacent vertical members by aligning and fixing heat dissipating pieces, and through this connection, external heat transfer fins are vertically formed by combining the heat dissipating pieces around the primary heat transfer tube. Features: Heat radiation tubes for natural convection heat exchangers. [Claim 2] An internal heat transfer fin is provided between each adjacent vertical member to protrude toward the center of the primary heat transfer tube, and the internal heat transfer fin is inserted between the vertical members and fixed integrally. A heat radiation tube for a natural convection heat exchanger according to claim 1. 3. The natural convection heating system according to claim 2, wherein each internal heat transfer fin is made of a plate material, and the plate material is sandwiched between adjacent external heat transfer fins. Heat dissipation tube for exchanger. 4. Natural convection type heat according to claim 2 or 3, characterized in that the internal heat transfer fins are divided into upper and lower stages, and are bent or twisted left and right in stages. Heat dissipation tube for exchanger. 5. The internal heat transfer fins, which are divided into upper and lower stages, pass through the center of the tube and are sandwiched between opposing vertical members and are fixed integrally. A heat radiation tube for a natural convection heat exchanger according to items 2 to 4. 6. A plurality of vertical members are formed by longitudinally elongated heat transfer plates, and when forming the vertical members, an arc-shaped plate is formed by press molding to form a primary heat transfer surface forming a part of a certain circle at the center of the width. A tube wall is formed, both ends of which are bent in the radial direction of the circle, and heat dissipation pieces that serve as secondary heat transfer surfaces are protruded from both ends,
A method for manufacturing a heat radiation tube for a natural convection heat exchanger, characterized in that vertical members are successively connected by aligning and fixing heat radiation pieces of adjacent vertical members.