JPH0123717B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat exchange wall formed by joining a thin plate having a large number of through holes to a base material having a large number of grooves on its surface, and a method for manufacturing the same.

Conventionally, as a heat exchange wall of this type, a heat exchange wall as shown in Fig. 1 was used as an attempt to transfer heat from the surface of a pipe or plate to a liquid in contact with the pipe or plate with high efficiency, such as fluorocarbon liquid, liquid nitrogen, liquid oxygen, etc. is proposed.

A number of elongated cavities 2 are provided in the skin zone of the heat exchange wall 1 which is in contact with the liquid, and these cavities 2 communicate with the outside by a number of minute through holes 3. Such a heat exchange wall 1 is generally formed by forming a groove that will become the cavity 2 in the base material of the heat exchange wall 1 by mechanical cutting or plastic working such as knurling, and then from between the side walls 5 of the cavity 2. Many small through holes 3
A perforated plate 4 having a large number of through holes 3 is placed over a base material so that the perforated plate 4 is located directly above the cavity 2, and is manufactured by diffusion bonding or the like.

With a heat exchange wall having such a structure, when the heat exchange wall is heated to a higher temperature than the liquid in contact with the wall, vapor bubbles 6 are generated and grown within the cavity 2 as shown in FIG. 2. When the vapor pressure inside the cavity 2 becomes higher than that outside, some of the vapor bubbles 6 are released from the through hole 3 and separated. The remaining vapor bubbles remain within the cavity 2 and are retained. At this time, a pressure change occurs in the cavity 2, and liquid enters the cavity 2 as shown by the arrow 7 from the through hole 3 from which the vapor bubbles 6 were released and another through hole 3'. The intruding liquid flows into the four corners of the cavity 2 by capillary force, forming a meniscus 8 with an extremely thin liquid film. Evaporation occurs from the thin liquid film of this meniscus 8, and the cavity 2
The steam bubbles 6 inside are grown. In this way, the cycle of growth and release of vapor bubbles and intrusion of liquid is repeated one after another.

However, since the through hole 3 is installed above the cavity 2, the liquid flowing from the through hole 3 into the meniscus 8 at the four corners of the cavity 2 passes through the back surface of the perforated plate 4 and flows into the four corners of the cavity 2. The intruding liquid cannot directly flow into the four corners of the cavity 2. Even if the position of the through-hole 3 is shifted so that it overlaps the side wall 5 of the cavity 2, as long as the perforated plate 4 with pre-drilled holes is joined, the flow path surface of the intruding liquid formed by the through-hole wall and the side wall will be This creates unevenness and makes it impossible to smoothly contact the four corners of the cavity 2. Therefore, when the degree of superheating of the heat exchange wall 1 is high, the flow resistance for the invading liquid is large, so that the replenishment of the liquid in the cavity 2 cannot keep up with the evaporation of the meniscus 8, and eventually the inside of the cavity becomes dry. become. This cannot improve the heat transfer performance of the heat exchange wall.

On the other hand, the heat exchange wall shown in Figure 1 is manufactured by forming grooves in the heat exchange wall base material and then bonding a perforated plate onto the grooves, so the accuracy of the groove pitch and the hole pitch of the perforated plate is not good. However, when bonding them together, there is a drawback that the opening positions are shifted. Furthermore, since the opening of the perforated plate and the joining of the perforated plate are performed in separate steps, productivity is low. In addition, diffusion bonding has traditionally been used to bond the heat exchange wall base material and the perforated plate, but such bonding requires equipment such as a large vacuum heating furnace, which increases production costs. Very large.

The object of the present invention is to remedy the above-mentioned drawbacks and provide an efficient and inexpensive heat exchange wall, as well as an inexpensive method for producing such a heat exchange wall. be.

To achieve this object, the present invention provides a heat exchange wall formed by bonding a thin plate to a base material having a large number of grooves on the surface, the thin plate having approximately semicircular openings formed on the grooves. The groove is characterized in that a through-hole is formed by integrating a substantially semicircular opening portion facing a substantially semiconical groove formed in the upper part of the side wall of the groove. Another feature of the present invention is that after providing a large number of elongated grooves in a base material that will become a heat exchange wall, a thin plate that will become a skin of the heat exchange wall is installed on the base material, and then A laser beam or an electron beam is irradiated from above to the thin plate above the groove so as to partially catch the side wall of the groove, and by this beam irradiation, a substantially semi-conical groove is formed on the upper side wall of the groove; A substantially semicircular opening facing the semiconical groove and a through hole in which the substantially semicircular opening on the elongated groove are integrated are formed in the thin plate, and the beam irradiation simultaneously causes the base plate to open. The method of manufacturing a heat exchange wall is characterized by also joining materials and thin plates.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

A large number of elongated cavities 11 are formed under the skin 10 of the heat exchange wall 9. A skin 10, which is the ceiling of the cavity 11, is provided with a large number of through holes 12 that are regularly opened along the cavity 11, and the cavity 11 communicates with the outside through the through holes 12. Through hole 12
When viewed from directly above the cavity 11, the opening 12a is approximately semicircular, and the opening 12b is approximately semicircular and faces the approximately semiconical groove 14 formed in the upper part of the cavity side wall 13. are formed together.

A heat exchange wall having such a structure can be easily manufactured as follows.

First, mechanical cutting is performed on the base material of the heat exchange wall 9.
Alternatively, after forming a large number of elongated groove-shaped cavities 11 by plastic processing such as knurling, a thin plate that will become the skin 10 of the heat exchange wall 9 is placed on the heat exchange wall surface, and a laser beam or an electron beam is applied to the side wall of the cavity. Irradiate so that it partially catches on 13. For this reason, the beam allows the skin 1, which forms the ceiling of the cavity 11, to
0 is provided with an approximately semicircular opening 12a, while the skin 10 on the cavity side wall 13 and the cavity side wall 13 are provided with an approximately semicircular opening 12b and an approximately semiconical opening 12b opposite the opening 12b. A shaped groove 14 is drilled. Then, a through hole 12 communicating with the cavity 11 and the outside is formed. At this time, the thin plate of the skin 10 has through holes 12
The peripheral portion of is welded to the cavity side wall. That is,
By laser processing or electron beam processing, it is possible to open holes in the skin and weld the skin in one step.

This manufacturing method can be used not only for flat plates but also for circular tubes. In the case of a circular tube, the heat exchanger tube can be easily manufactured by wrapping a thin plate serving as the skin and applying laser processing or electron beam processing.

When the heat exchange wall constructed in this way is heated to a higher temperature than the liquid in contact with it, the cavity 1
Steam bubbles are generated and filled inside 2. When the pressure of the vapor bubble becomes higher than the pressure of the external liquid, the through hole 1
A part of the steam bubbles is released from 2, and other steam bubbles are retained in the cavity 11 as residual steam bubbles. At this time, a pressure change occurs in the cavity 11, and liquid flows into the cavity 11 from the through hole 12 from which the vapor bubbles were released and another through hole 12. The inflowing liquid is carried to the four corners of the cavity 11 by capillary action, and the liquid film forms an extremely thin meniscus. Since the inlet of the through hole 12 has a smooth conical shape and is directly connected to the corner of the cavity 11, the liquid can easily flow in, and the liquid can be smoothly replenished against evaporation from a thin liquid film. be exposed.

In the embodiment explained in FIGS. 3 and 4, the sizes of the many through holes are made almost uniform, but in the other embodiment shown in FIG. 5, the size of the through hole 12 is changed. This is a case where they are made to differ by a certain interval. If the sizes of the through-holes 12 are different, the flow resistance of the through-holes 12 will be different, so the steam generated in the cavity 11 will always flow to the through-hole 1 with the larger opening.
It releases and leaves from 2'. Further, external liquid flows into the cavity 11 through the small through hole 12''.
If the through-holes 12 are uniform in size, it is difficult to keep the apertures for releasing steam and the apertures for liquid inflow always at fixed locations. However, if the sizes of the through holes 12 are made to vary regularly, the cycle of steam release and liquid inflow can always be stabilized, and the boiling heat transfer performance is improved.

FIG. 6 is an experimental example showing the effect of the present invention.
A comparison of the boiling performance of a heat transfer wall manufactured by the method of the present invention and a conventional heat transfer wall (using the refrigerant Freon R11) is shown. The horizontal axis shows the superheat degree ΔT (°C) of the heat transfer wall surface from the saturation temperature of the refrigerant liquid, and the vertical axis shows the heat flux q (W/cm ² ). In Figure 6,
Each curve A, B, C has a cavity pitch of 0.55 mm and a depth of 0.4
mm, through-hole pitch 0.7 mm, skin thickness 0.05 mm, etc. are the same. Curve A corresponds to the structure shown in FIG. 1, where the size of the through hole is 0.1 mm.
Curve B is for the structure of the present invention shown in FIG. 3, and the diameter of the upper part of the through hole is approximately 0.1 mm. Curve C shows the structure of another embodiment of the invention shown in FIG. 5, in which the diameter of the large aperture is approximately 0.15 mm and the diameter of the small aperture is approximately 0.1 mm.
It is. As is clear from this figure, when the heat flux increases, the degree of superheating of curve B becomes smaller than that of curve A when the heat flux is the same. Furthermore, curve C has a smaller degree of superheat than curves A and B. Thus, it is clear that the heat exchange wall of the present invention has higher heat transfer performance than the conventional heat exchange wall.

Incidentally, particles scattered by laser beam processing and electron beam processing adhere to the inner wall surface of the cavity, so that the wettability of the liquid film and the spreading property of the liquid film are improved, and furthermore, the boiling heat conductivity is improved.

As described above, according to the heat exchange wall of the present invention, a substantially semiconical groove is formed in the upper part of the side wall of the cavity (groove), and a through hole having a substantially semicircular opening facing the groove is formed. Since the holes are formed in a thin plate, the flow path surface for the liquid that enters the cavity is smooth, making it easier for the liquid to flow into the cavity, making it possible to smoothly replenish the liquid against evaporation from the thin liquid film inside the cavity. It will be done. As a result, there is an effect that boiling heat transfer performance can be improved.

Further, according to the method of manufacturing a heat exchange wall of the present invention, a laser beam or an electron beam is irradiated from above the thin plate to the thin plate above the groove so that a part of the thin plate is caught on the side wall of the groove. A substantially semi-conical groove is formed in the upper part of the side wall, and a through hole having a substantially semi-circular opening facing the semi-conical groove is formed in the thin plate, and at the same time, the beam irradiation is performed to form a substantially semi-conical groove in the base material. Since it is also bonded to a thin plate, the heat exchange wall with high boiling heat transfer performance described above can be easily produced. That is, the beam irradiation has the advantage that the processing of the through hole and the semi-conical groove and the joining of the base material and the thin plate can be performed in one step.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of a conventional heat exchange wall, FIG. 2 is a perspective view of the heat exchange wall of FIG. 1, and FIG. 3 is a perspective view of the heat exchange wall of the present invention. FIG. 4 is a partially cutaway perspective view of one embodiment, FIG. 4 is a front view with the skin of a portion of the heat exchange wall of FIG. 3 removed, and FIG. 5 is a partial view showing another embodiment of the heat exchange wall of the present invention. FIG. 6 is a cross-sectional perspective view showing the boiling heat transfer performance of the heat exchange wall of the present invention and the conventional heat exchange wall. 9... Heat exchange wall, 11... Cavity, 12... Through hole, 13... Cavity side wall, 14... Conical groove.

Claims (1)

[Scope of Claims] 1. A heat exchange wall formed by joining a thin plate to a base material having a large number of grooves on its surface, the thin plate having approximately semicircular openings formed on the grooves and the grooves. A heat exchange wall characterized in that a through hole is formed in which a substantially semicircular opening portion opposing a substantially semiconical groove formed in an upper part of a side wall is integrated. 2. The method according to claim 1, characterized in that the sizes of the through holes provided in the thin plate bonded to the base material are made to vary regularly along the grooves provided on the surface of the base material. heat exchange wall. 3 After providing a large number of long and narrow grooves in the base material that will become the heat exchange wall, a thin plate that will become the skin of the heat exchange wall is installed on the base material, and then a laser beam or an electron beam is applied to the base material from above the thin plate. The thin plate above the groove is irradiated so as to be partially caught on the side wall of the groove, and this beam irradiation creates a substantially semi-conical groove in the upper side wall of the groove and a semi-conical groove in the thin plate. A through hole is formed in which the opposing substantially semicircular openings and the substantially semicircular opening on the elongated groove are integrated, and the base material and the thin plate are simultaneously joined by the beam irradiation. A method of manufacturing a heat exchange wall characterized by: