JPS63306399A - Heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat exchange device, and more particularly, to a heat exchange device that increases the heat transfer efficiency between a heating surface in a so-called nucleate boiling region and a boiling liquid.

(Prior Art and Problems) Heat transfer between a heating surface and a boiling liquid is known as an effective means of heat exchange. Often used.

In order to improve the heat transfer efficiency due to the boiling phenomenon, conventionally, by forming as many so-called nucleation points, e.g. cavities, as possible on the heating surface, steam bubbles are generated more easily on the heating surface. It was designed to increase the nucleate boiling of the liquid. Some examples of specific means are as follows.

U.S. Patent Nos. 4,074,753 and 3,990.8
No. 62 proposes coating the heating surface with a net layer, adhering a porous metal sintered body to the heating surface, or wrapping a wire rod around the heating surface if it is tubular.

Also, U.S. Patent Nos. 3,696,861 and 4.15
No. 9.739 proposes machining the heated surface to form cavities that provide multiple nucleation points.

All of the above conventional techniques do nothing but generate more bubbles at the nucleation points of the heating surface, and are certainly effective in improving heat transfer efficiency.

However, the above-mentioned conventional technology has a problem in that the heat transfer efficiency cannot be sufficiently increased when the heating surface is a cylindrical inner circumferential surface such as a tube material or the inner surface of a small-sized heating body having a small shape.

(Purpose) The present invention was made to solve the above problems,
A heat exchange device that can effectively improve heat transfer efficiency by utilizing the stirring action of the bubbles and liquid by the steam bubbles generated on the heating surface, regardless of the shape of the heating surface, to promote heat exchange between the two. The purpose is to provide

(Structure) The present invention is a heat exchange device for exchanging heat between a heating surface and a boiling liquid, in which a heating surface, a covering member covering the heating surface, and the covering member are arranged at a predetermined distance from the heating surface. having a supporting member for supporting, and providing a through hole in the covering member;
It is characterized in that steam bubbles generated by nucleate boiling on the heating surface flow through a passage formed in a space between the heating surface and the covering member and flow out from the through hole.

(Function) Generally, a heater in a heat exchange device using boiling liquid is formed using a material with good heat transfer properties.

If the wall thickness ΔX is of a normal size, the heat transfer coefficient /ΔX in the heated wall is several times larger than the heat transfer coefficient in the heated surface. If the heat transfer coefficient of the heating surface can be increased, the overall heat transfer effect can be enhanced.

According to the present invention, the heat transfer coefficient of the boiling liquid on the heating surface of the heat exchange device can be increased regardless of the size of the heating surface.

That is, a space is formed by coating the heating surface with a metal or non-metallic layer at appropriate intervals, and this space is used as a passage for vapor bubbles to flow, so that the vapor bubbles generated during liquid boiling are brought very close to the heating surface. It can be moved in the same state. The passageway is formed vertically or upwardly inclined, and a through hole is opened in the upper part of the passageway so that air bubbles moving upward along the heating surface are discharged through the through hole.

By limiting the distance between the surface of the covering member and the heating surface to an appropriate size, the liquid and bubbles on the heating surface can be stirred, and the heat transfer efficiency can be effectively increased.

The thickness of the covering member is not particularly limited, but it may have any shape as long as its surface is substantially parallel to and facing the heating surface. This covering member may be either metallic or non-metallic and may be of either permeable or impermeable construction. The covering member having a permeable structure may be a reticulated fabric or cloth, a perforated sheet, or another material having pores. In this case, the diameter or width of the pores is preferably equal to or less than the 1,0-order layer.

The above-mentioned through hole is preferably provided above the steam passageway or on the ceiling, and especially if the passageway is quite long, it is additionally provided below or at the bottom of the passageway. Each through hole is preferably 0,5
They are provided at intervals of cm to 20 cm. This spacing may be approximately equal to or greater than the cross-sectional diameter of the passageway.

As a support member that maintains a constant distance between the covering member and the heating surface, for example, (1) small protrusions provided at a predetermined interval on the heating surface or the surface of the covering member, (2) in place of the small protrusions in (1) above. (3) small protrusions formed on a sheet-like covering member by press molding, etc.; 4) A convex strip formed by a press molding method etc. in place of the small protrusions in (3) above, (5) A short columnar or elongated rod-shaped stay member attached to the heating surface or one side of the covering member, or (6) The covering member can be held at an appropriate distance from the heating surface using a stay bolt or the like. The distance between the heating surface and the covering member is preferably 0
．． 05yx-10x*, the diameter or width of the supporting member itself is 0.1 zx to 10+u, and the spacing between each supporting member is substantially 0.2 mm to 300 RR.

(Examples) The present invention will be described with reference to the accompanying drawings showing some examples.

1 to 5, the covering member 2 is shown along the heating surface l.
are covered and held at approximately a predetermined distance by a supporting member 6 of a height located between them. 3 is the heating surface l and the covering member 2
a passage formed from a space defined by one side of the heating surface 3, which is adapted to move the steam bubbles vertically or obliquely upwards close to the heating surface 1. The bubbles that have ascended through the passage 3 are released from the through hole 5. In addition,
The height of the support member 6, i.e. the spacing defining the passageway 3, is generally 0.05RII-10zm, preferably 0.
, l yr! ~5yx, and a towing support member 6 is provided so as to extend substantially in the upward direction of the bubbles, forming a plurality of passages 3.

The through hole 5 is usually provided at the upper end of the passage 3;
If the bubbles are quite long, a large number of through holes 5 are provided at certain intervals in the upward direction of the bubbles, as shown in the figure. Through hole 5
The cross-sectional area may be approximately the same size as the cross-sectional area between the supporting members 6 in the cross section of the passage 3, or may be larger than that.

The opening shape of the through hole 5 may be square, rectangular, polygonal, circular, oval, or oval.

Impermeable or permeable materials can be used as covering members.

When using a permeable material, the diameter of each through hole is l, Oz
tx, and the entire surface of the heating surface l is covered with one coating member 2 or by arranging a large number of strip members 21 in parallel as shown in FIGS. 23, 25, and 33. You may. In the latter case, the abutment or gap 51 of each strip member 21 as shown in FIGS. 31 and 34 functions similarly to the through hole 5.

In addition, a plurality of through holes are provided at the bottom and end of the passage 3, and especially when a permeable member is used, the lowermost end is opened to a sufficient width to allow liquid to circulate across both sides of the covering member 2. Can be done. When gaps 51 and 52 are provided, their through holes or openings can be omitted.

6 to 9 show modified examples of the support means. In the drawing, small protrusions 61 are formed on the covering member 22, and each small protrusion 61
The tip of the heating surface is pressed or adhered to the heating surface via some kind of attachment means. On the contrary, a plurality of small projections 62 may be provided on the heating surface 11, and the tip of each small projection 62 may be pressed against or adhered to the covering member 2.

Furthermore, FIG. 10 shows that a large number of stay members 63 are formed from metal or non-metallic materials, and these stay members 63 are interposed between the heating surface l and the VT cover member 2 by some kind of attachment to the surface of either one. An embodiment is shown in which the two surfaces are made to face each other by being attached via means.

The small protrusions 61, 62 or the stay member 63 can be formed into a spherical, hemispherical, conical, truncated conical, pyramidal, cylindrical, or prismatic shape. In addition, these small protrusions or stay members are, for example, as shown in FIGS. 11, 12, and 13, vertically elongated protrusions 64 extending in the flow direction of bubbles shown by arrows on the covering member 23, or As shown in Figure 14, the heating surface! 2, a vertically elongated convex strip 6 elongated in the same manner as described above.
It can also be set to 5.

FIG. 15 shows an embodiment in which a plurality of vertically elongated convex strips 66 are provided on the heating surface 1 or the covering member 2 so that the surfaces of the harmful heating surface 1 and the covering member 2 are opposed to each other with a predetermined interval. Vertical convex strip 66
is formed into a round bar with a predetermined diameter, a square bar with a predetermined width and thickness, or a bar with various other cross-sectional shapes, and these are attached to the heating surface by some attachment means! Alternatively, it can be attached to the covering member 2 to function in the same manner as the above-mentioned protruding strip 64. In particular, when the heating surface l is the outer circumferential surface of a cylindrical body, the covering member 2 may be wrapped around this outer circumferential surface or
When is the inner circumferential surface of the cylindrical body, it may be wound around the outer circumferential surface of the covering member 2 facing the heating surface l. As is clear from this, the protruding stripes 66 are not limited to being made of a flexible material, and may be made of rope, string, cotton thread, etc., for example.

When a metal sheet is used as the covering member 2, the small protrusions 61 and the protrusions 64 can be formed as shown in FIGS. 16 to 18 and 19 to 21. That is, the protrusions 67 and the protrusions 68 can be formed on the covering member 24, 25 made of a thin strip material by a press working method or the like. In short, by bringing the tips of these protrusions or convex stripes into pressure contact with the heating surface I! A passage 3 is formed between both surfaces of the covering member 2 so that the flow of bubbles is directed as shown by the arrow in FIG. The diameter of the protrusion 67 and the width of the protrusion 68 are set to be 10IIR or less. Further, these protrusions may be formed in a curved wave shape, trapezoid, or chevron shape with appropriate spacing. Convex strip body 68
In this case, a plurality of protrusions 68 having a certain length may be arranged in a chain or in a continuous manner.

A stay tube 69 is used as a modification of the support member 6, and as shown in FIG.
Insert 9 and bolt 69 to these! It can also be fixed by screwing it on. In this case, the length of the stay tube 69 is preferably 0.05 mm or more! It is considered to be the OR shoulder.

The support member 6 includes protrusions 61, 62, 67, and protrusions 64.
．． 65.68, regardless of the form of the stay member 63, the convex strip 66, or the stay tube 69, the heating surface 1
The distance between and the covering member 2 is 0.05jIx~lo on the entire surface
zm, preferably 0.1 to 5 cm. Moreover, these supporting members 6 have a thickness of 0.2 mm to 3 mm.
00 am, preferably 0.5 RM to 50 RR, and each support member 6 has a diameter or width of 0 am,
lmm~! Ou1 preferably 0, 3 II! x~
3ffj+.

In the heat exchange device of the present invention, the heating surface 1 covered with the covering member 2 may have any shape. In other words, as long as the periphery forms a closed container surrounded by walls, the area of the heating surface of a small heat exchanger is small, the inner peripheral surface of a cylindrical shape, or the outer peripheral surface of a cylindrical body. Good too. Further, these can be applied to evaporators of refrigeration equipment and air conditioning equipment, and the like.

In the embodiment shown in FIGS. 23 and 24, the inner circumferential surface 13 of the tubular body 4 arranged almost horizontally is used as the heating surface, and the tubular covering member 26 having a smaller diameter than the tubular body 4 is attached to the inner circumferential surface. 13 via a plurality of supporting members 6 arranged at intervals in the axial and circumferential directions, and the outer peripheral surface of the covering member 26 and the inner peripheral surface 13 maintain a predetermined distance. As the support member 6 in this embodiment, any of the various embodiments described above can be applied. The covering member 26 is provided with a through hole 5 for vapor outflow. Note that the tubular body 4 may extend vertically or inclined at a desired angle. With this configuration, the liquid in the tube body 4 is heated, and the bubbles generated on the heating surface I3 are quickly separated from there and passed through the space between the heating surface I3 and the inner circumferential surface 13 of the tube body 4. 3 moves upward, enters the passage 3 from the space through the through hole 5, and quickly mixes with the steam bubbles flowing through the passage 3, thereby enhancing the heat transfer effect.

In the embodiment shown in FIGS. 25 to 27, the inner peripheral surface of the tube 4 is arranged almost horizontally! 3 is a heating surface, and a covering member 27 is inserted to cover the heating surface. A crack groove 52 is provided along the longitudinal axis in the upper part of the covering member 27, and the crack groove 52 functions similarly to the through hole described above. On the other hand, a plurality of through holes 5 are provided discontinuously in the lower part or bottom of the covering member 27. The support members 6 are arranged at predetermined intervals in the axial and circumferential directions, as in the above embodiment. The gap 52 functions to swing the steam bubbles in the axial direction after rising.

In addition, when the tube body is quite long, the insertion work into the tube body can be facilitated by dividing the covering member 26, 27 into several parts in the axial direction.

In the embodiment shown in FIGS. 31 and 32, the inner circumferential surface 14 of the horizontally arranged pipe body 4 is used as a heating surface, and a plurality of covering members 28 are attached to support members 6 and 6 so as to cover the heating surface. Formed with support through.

A groove 52 is formed in the upper part of each covering member 28 along the vertical axis. These covering members 28 are arranged in a row along the longitudinal axis of the tubular body 4 with a gap 5I between them. As the support member 6, any of the embodiments described above may be applied. In short, these supporting members may be appropriately arranged in the axial and circumferential directions. The slot 52 has the same function as the through hole described above, and the through hole 5 is provided only in the lower part or bottom of the covering member 28. Although the tubular body 4 is arranged horizontally in this embodiment, it is not limited thereto, and may be arranged vertically or inclined at a desired angle. The gaps 51 between the respective covering members 28 also function as through holes. The size of this gap 51 is selected as appropriate, as long as it can facilitate attachment of the covering member 28 to the tube body 4.

In the embodiment shown in FIGS. 33 and 34, the outer circumferential surface 14 of the vertically disposed tube 4 is used as a heating surface. A cylindrical covering member 29 of Im is held via the supporting member 6 with a desired gap 51 in the vertical axis direction so as to cover the outer circumferential surface 14 . Each support member 6 can be the same as described above, and is appropriately arranged in the axial and circumferential directions of the tube body 4. Note that in this embodiment, the through hole is omitted, and the function of the through hole is performed by the gap 51. Further, the tube body 4 is not limited to being vertical, but can be inclined at a desired angle.

FIGS. 28 and 29 show yet another modification. The tubular body 4 is arranged horizontally, and its outer peripheral surface 14 is covered with a cylindrical covering member 20 as a heating surface. Through holes are provided in the upper and lower parts of the cylindrical covering member 20, respectively. The passage 3 is formed by winding a supporting member 6 made of a metal or non-metallic material such as a string, rope, single wire, or rod in a spiral or loop shape around the tube body 4 .

The embodiment shown in FIG. 30 shows the outer circumferential surface of the horizontally arranged tube body 4! 4 is a heating surface, and the heating surface is covered with a covering member 22 or 24 at a predetermined interval. The covering member 22 or 24 has a small protrusion 61 as shown in FIG. 7 or a protrusion 67 as shown in FIG. 17 formed by, for example, a press method. These small projections 61 or projections 67 are arranged regularly in the axial and circumferential direction of the covering member 22 or 24. Note that the tubular body 4 is not limited to being horizontal, but may be arranged vertically or inclined at a desired angle.

(Effects) The effects of the heat exchange device having the above configuration will be explained together with a comparative test example with a conventional device.

In the comparative test, the device of the present invention and the conventional device were operated under the same conditions, and the heat transfer coefficient h1 was calculated according to the formula below.
I compared it with. The test was conducted using water at atmospheric pressure and under conditions where the heat flux in both devices was the same.

In the formula, T1 and T are the maximum temperatures of the heating surfaces of the conventional device (hereinafter referred to as a comparative example) and the device of the present invention (hereinafter referred to as an example), respectively.

The first comparative example tested was closed at both ends and had an outer diameter of 381 mm.
A steel pipe body having a wall thickness of 1R1 and a length of 7u1 and a length of 200aut is arranged horizontally in a water tank.

The copper tube body was heated in the atmosphere with an electric heater, and the surface temperature of the steel tube body was measured every minute using an alumel-chromel thermocouple for 5 minutes after the temperature of the steel tube body stopped rising. This was used as comparative data.

The first embodiment is constructed by covering a steel pipe body 4 similar to the steel pipe body described above with a covering member 24 formed by molding protrusions 67 as shown in FIGS. 16 to 18 using copper foil using a press molding method. It is something. The same measurements as in the first comparative example were carried out for this first example, and test data was collected. Note that the covering member 24 has a thickness of approximately 0.0 mm. 102RR, each protrusion has a diameter of about 4 mm, a height of about 1 x m, and is formed at a center distance of 10 x z from each other, and has a width of about 211 mm at the upper and lower parts of the covering member 24, respectively, as shown in FIG. A through hole 5 is provided.

The results of the above test are shown in Table 1.

Table 1 Heat flux (K W/foot 45 30 15 7.
5 First comparative example T, (°C) 110.5 108.5
106,5 104.5 First example T, ('C)
105.5 104.5 102.5 101.5h,
/h, 1,91 2.13 2.4
0 3.00 Next, about 2J of plastic twisted yarn having a thickness of about 1.2 II as disclosed in U.S. Pat. No. 4,074,753 was applied to the steel pipe body of the first comparative example.
A conventional type device formed by winding with IjI intervals was used as a second comparative example, and the above test was conducted using this second comparative example, and measurement data ('r, -t) was collected.

On the other hand, the outer periphery of a thread-wound pipe similar to the thread-wound pipe of the second comparative example was made to a thickness of about 0. Coated with copper foil of 102
2 was provided to form a second embodiment.

Using this second example, tests similar to those described above were conducted and measurement data ('r tz) was collected.

The above test results are shown in Table 2.

Table 2 Heat flux (KW/m”) 45 3G 15
7.5 Second Comparative Example T,! ('C) 106.5 10
4.5 103.0 102.0 Second example T*-t(
°C) 105.5 103.5 102.0 101.
3hl-,'/h, 1.62 1,8
9 2.00 2.25he-t/hl
2.10 2.43 3.00 3.4 Here, hl- and hl-2 represent the heat transfer coefficients of the second comparative example and the second example, respectively.

As is clear from Tables 1 and 2, the heat exchange device (first and second embodiments) according to the present invention is different from the conventional type device (
It can be seen that the efficiency is higher than that of the first and second comparative examples).

Furthermore, the present invention is not only applicable to any device using a conventional flat heating surface, but also can effectively enhance the nucleation point promotion effect by using the various modifications described above.

[Brief explanation of the drawing]

FIGS. 1 to 5 each show various embodiments of the heat exchange device of the present invention, and FIG. 6 is a sectional view of a main part of each embodiment, and FIG. 6 is a plan view of a covering member forming a support member applicable to the present invention. Fig. 7 is a sectional view taken along the line ■-■ in Fig. 6, Fig. 8 is a sectional view of the assembly of the covering member and heating surface shown in Fig. 6, and Fig. 9 shows a support member formed on the heating surface. 10 is a sectional view of an embodiment in which a stay member as a support member is formed on a flat heating surface or a covering member, and FIG. 11 is a plane view of a covering member in which a modified example of the supporting member is formed. Figure 12 is a sectional view taken along the line ■-■ of Figure ti, Figure 13 is a cross-sectional view of Figure 1.
14 is a sectional view of an assembly of a heating surface and a covering member on which a supporting member similar to the supporting member of FIG. 11 is formed; 15th The figure is a sectional view of a modification using a vertically long rod-shaped body as a support member, FIG. 16 is a plan view of a covering member forming another modification of the support member, and FIG. 17 is a A cross-sectional view taken along the line X, Figure +8 is a cross-sectional view of the assembly of the covering member and heating surface shown in Figure 16, and Figure 19 is a plan view of the covering member forming yet another modification of the support member. 20 is a sectional view taken along line xx-xX in FIG. 19, FIG. 21 is a sectional view of the assembly of the covering member and heating surface in FIG. 19, and FIG. 22 is a schematic diagram of another modification of the support member. 23 is a longitudinal sectional view of a modified example of the present invention in which a covering member is attached to a tube whose inner peripheral surface is a heating surface; FIG. 24 is a longitudinal sectional view of a modified example of the present invention;
25 is a longitudinal sectional view of another modification of the present invention, FIG. 26 is a sectional view taken along the xxvt-xxvt line of FIG. 25, and FIG. 27 is a sectional view taken along the line XX of FIG. 28 is a cross-sectional view of another modification of the present invention in which a covering member is attached to the outer periphery of a tube whose outer periphery is the heating surface; 29 is a sectional view taken along line XX FIG. 30 is a cross-sectional view of yet another modification of the present invention in which a covering member is attached to the outer circumference of a tube whose outer circumferential surface is the heating surface, and FIG. 31 is a cross-sectional view of the above-mentioned A cross-sectional view of still another modification of the present invention to which a modification of the covering member attached to the tube body is applied; FIG. 32 is a cross-sectional view taken along the line XXl-XXX1I of FIG. 31;
Fig. 33 is a cross-sectional view of yet another modification of the present invention, in which a covering member is attached to the outside of the upright tube whose outer peripheral surface is the heating surface; Fig. 34 is Fig. 33 (17) XXXIV-XXXrV line FIG. 1...Heating surface, 2...Coating member, 3...Steam bubble passage, 5...Through hole, 6...Supporting member, 13...Inner peripheral surface, 14...Outer periphery Surface, 20.22.24.26.27.28.29... Covering member, 51... Gap, 52... Division groove, 6I, 62... Small protrusion, 63... Stay member, 64
... Convex strip body, 66... Longitudinal convex strip body, 67... Protrusion, 68... Convex strip body, 69... Stay pipe, 691... Stay bolt.

Claims (17)

[Claims] (1) A heating surface, a covering member that covers the heating surface, and a supporting member that supports the covering member at a predetermined distance from the heating surface, and at least one through hole is provided in the covering member, and the heating surface is heated. A heating surface and boiling device characterized in that vapor bubbles generated by nucleate boiling of a liquid on the surface flow through a passage formed in a space between the heating surface and a covering member and flow out from a through hole. A heat exchange device that exchanges heat between liquids. (2) Claim 1, wherein the covering member is an impermeable metal member, an impermeable non-metal member, or a permeable metal member or a permeable non-metal member provided with a plurality of holes with a diameter of 1.0 mm or less. The device described. (3) The distance between the surface of the covering member and the heating surface is 0.05 mm to 10 mm.
2. A device according to claim 1, supported substantially parallel with a spacing of 0 mm. (4) The device according to claim 1, wherein the through hole is formed in the upper part of the steam bubble passage. (5) Multiple through holes 0.5 cm above the steam bubble passage
2. A device according to claim 1, formed with a spacing of ~20 cm. (6) Claim 1, wherein the covering member is a thin layer sheet.
Apparatus described in section. (7) Claim 1 in which a plurality of covering members are arranged
Equipment described in Section. (8) The device according to claim 1, wherein the through hole has a size approximately equal to the cross-sectional area of the steam bubble passage. (9) The device according to claim 1, wherein the through hole is slightly larger in cross-sectional area than the steam bubble passage. (10) Each support member is formed with a height of 0.05 mm to 10 mm, a width of 0.1 mm to 10 mm, and
．． 2. The device according to claim 1, wherein the device is arranged with a spacing of 2 mm to 300 mm. (11) The apparatus according to claim 10, wherein each support member is a stay member disposed between the heating surface and the covering member. (12) The device according to claim 10, wherein each support member is a protrusion that protrudes from either the opposing heating surface or the surface of the covering member and comes into contact with the opposing surface. (13) The device according to claim 10, wherein the tip of each protrusion is integrally connected to the opposing surface. (14) Claim 10, wherein each support member is formed in a vertically elongated shape and arranged at intervals in the horizontal direction;
The apparatus according to any one of clauses 12 and 13. (15) The device according to claim 1, wherein the support member is a rod-shaped member disposed between the heating surface and the covering member. (16) The device according to claim 15, wherein the rod-shaped member is formed from a flexible material. (17) The device according to claim 1, wherein the support member is a stay bolt that supports the heating surface so as to cover the covering member at a predetermined interval.