JPH08247343A - Heating pipe and manufacture thereof - Google Patents

Abstract

PURPOSE: To enhance heat transfer efficiency of a heat transfer pipe and improve its heat exchanging quantity and heat transfer quantity by providing many dimples on the tube inner peripheral surface of the heating pipe. CONSTITUTION: A number of dimple (recess) 10 are provided on the tube internal peripheral surface of a heat transfer pipe 5 in a heat exchanger, etc. Each dimple 10 has a diameter d of about 0.1 to 0.5mm#, a depth h of about 0.1 to 0.5mm, a pitch p of about (1 to 3)d. For the purpose of manufacturing such a heat transfer pipe 5, a flat plate is placed on the lower mold, and lowered by the actuator of the upper mold on whose bottom surface projections 13 are formed and by thus pressing the flat plate, many dimples are formed on the surface of the plate. Then, this plate is set on a bender, etc., the plate is subjected to slow bending work so that the dimples may be placed inside and mutually opposite surfaces on both ends in the inner peripheral direction of the cylindrically processed plate are seam welded by a welding torch and thus the processes are completed. By means of this sort of heat transfer pipe 5, its heat transfer efficiency can be extremely improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer tube and a method for manufacturing the heat transfer tube.

[0002]

2. Description of the Related Art Conventionally, there are various types of heat exchangers, one of which is shown in FIG. 7, for example.

In FIG. 7, reference numeral 1 denotes a vertical cylindrical cylinder 5 having a primary fluid inlet 3 for introducing the primary fluid 2 in the lower portion and a primary fluid outlet 4 for letting out the primary fluid 2 in the upper portion. A large number of heat transfer tubes 6 housed in the case 1 so as to extend in the vertical direction are provided on the upper side of the case 1 to transfer the secondary fluid 7 to the heat transfer tube 5.
A secondary fluid inflow portion for feeding to the secondary fluid outflow portion 8 is a secondary fluid outflow portion for outflowing the secondary fluid 7 flowing down in the heat transfer tube 5.

In the above heat exchanger, the primary fluid inlet 3
The primary fluid 2 that has flowed into the body 1 from the ascends in the body 1 and flows out of the body 1 from the primary fluid outlet 4 and the secondary fluid 7 that has flowed into the heat transfer tube 5 from the secondary fluid inlet 6 is transferred. It flows down in the heat pipe 5 and flows out to the secondary fluid outflow portion 8.

Thus, when the primary fluid 2 rises in the body 1 and the secondary fluid 7 flows down in the heat transfer tube 5, heat is generated between the primary fluid 2 and the secondary fluid 7 through the wall of the heat transfer tube 5. The exchange takes place, heating one fluid 2 or 7 and cooling the other fluid 7 or 2.

[0006]

In the above heat exchanger, as shown in FIG. 8, since the inner peripheral surface of the heat transfer tube 5 in contact with the secondary fluid 7 is flat, the fluid resistance of this portion is large, Therefore, the flow velocity of the secondary fluid 7 is significantly reduced at the contact portion with the inner peripheral surface of the heat transfer tube 5 as shown by the flow velocity distribution 9, and there is a problem that the heat transfer efficiency of the heat transfer tube 5 is low.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat transfer tube having high heat transfer efficiency and a method for manufacturing the heat transfer tube.

[0008]

The heat transfer tube of the present invention is provided with a large number of dimples on the inner peripheral surface of the tube.

Further, according to the method of manufacturing a heat transfer tube of the present invention, a plate having a large number of dimples formed on its surface is pressed into a cylindrical shape so that the timples are on the inside, and both ends in the circumferential direction of the cylindrical processed plate. The mating surfaces are seam welded.

[0010]

In the heat transfer tube of the present invention, when the fluid flows in the heat transfer tube, the flow of the fluid easily separates from the inner peripheral surface of the heat transfer tube, so that the flow velocity of the fluid at the inner peripheral surface of the tube increases and the heat exchange amount increases. Further, when heating the heat transfer tube, bubbles are likely to be generated, and it can be expected that the phase change is promoted. Since the heat transfer form changes from convective heat transfer to boiling heat transfer, the amount of transferred heat increases.

According to the method of manufacturing the heat transfer tube of the present invention, the heat transfer tube can be easily manufactured.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 6 show an embodiment of the present invention.

In the embodiment of the present invention, as shown in FIG. 1, a large number of dimples (indentations) are formed on the inner peripheral surface of the heat transfer tube 5.
10 is provided. As shown in FIG. 2, the dimple 10 has a diameter d≈0.1 to 0.5 mmφ and a depth h≈0.1 to 0.5 m.
m, pitch p≈ (1 to 3) d.

When manufacturing the heat transfer tube 5, as shown in FIG. 3, a flat plate 12 is placed on a fixed lower mold 11 and an upper mold 14 having projections 13 formed on the lower surface thereof. Is lowered by an actuator and the plate 12 is pressed.

Thus, a large number of dimples 10 are formed on the upper surface of the plate 12 by pressing, as shown in FIG.

Then, as shown in FIG. 5, the plate 12 is gradually bent by a bender or the like so that the dimples 10 are located inside, and when the plate 12 is formed into a cylindrical shape, the opposing surfaces at both ends in the circumferential direction are processed. As shown in FIG. 6, seam welding is performed by the welding torch 15. When the seam welding is completed,
The tube for the heat transfer tube 5 is completed.

The heat transfer tube 5 of the heat exchanger shown in FIG.
When used for the heat transfer tube 5, the secondary fluid 7 flowing down in the heat transfer tube 5 is easily separated from the inner peripheral surface of the heat transfer tube 5 due to the dimples 10. Therefore, the flow velocity of the fluid on the inner peripheral surface of the heat transfer tube 5 is as shown in FIG.
Flow rate distribution 9 increases, the heat exchange efficiency improves, and the amount of heat exchanged increases.

Further, the heat transfer tube 5 is connected to the primary fluid 2 or the secondary fluid 7.
When heated by, the inner peripheral surface of the heat transfer tube 5 is dimple 10
This facilitates the generation of bubbles, which can be expected to accelerate the phase change, and when the phase change is promoted, the heat transfer form changes from convective heat transfer to boiling heat transfer, which improves heat exchange efficiency and increases the amount of heat transferred. Will increase.

Further, the heat transfer tube 5 can be manufactured easily and quickly through simple steps.

The heat transfer tube 5 of the present invention can be used not only for ordinary heat exchangers but also for all heat exchangers such as evaporators and condensers, and the diameter, depth and pitch of dimples can be transferred. It goes without saying that the diameter varies depending on the diameter of the heat tube, and that various changes can be made without departing from the scope of the present invention.

[0022]

According to the heat transfer tube and the method for manufacturing the heat transfer tube of the present invention, in the case of claim 1, the heat transfer efficiency is increased and the exchange heat quantity and the transfer heat quantity can be improved. In the case of 2, it is possible to produce various excellent effects such that the heat transfer tube can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a heat transfer tube of the present invention.

FIG. 2 is a detailed view of a dimple portion of the heat transfer tube of FIG.

FIG. 3 is a front view showing a state in which a plate is pressed to form dimples in the method for manufacturing a heat transfer tube of the present invention.

FIG. 4 is a perspective view showing a state of a plate on which dimples are formed by pressing in the method for manufacturing a heat transfer tube of the present invention.

FIG. 5 is a perspective view showing a state in an intermediate stage of processing a plate into a cylindrical shape in the method for manufacturing a heat transfer tube of the present invention.

FIG. 6 is a perspective view showing a state in which a tube processed into a cylindrical shape is seam welded in the method for manufacturing a heat transfer tube of the present invention.

FIG. 7 is a vertical sectional view of an example of a general heat exchanger.

8 is a vertical cross-sectional view of a heat transfer tube used in the heat exchanger of FIG.

[Explanation of symbols]

 5 Heat transfer tube 10 Dimple 12 Plate

Claims (2)

[Claims] 1. A heat transfer tube having a large number of dimples provided on the inner peripheral surface of the tube. 2. A plate having a large number of dimples formed on its surface by pressing is processed into a cylindrical shape so that the dimples are on the inner side, and seam welding is performed on the circumferentially opposite ends of the cylindrically processed plate. And a method for manufacturing a heat transfer tube.