JPH04116391A - Heat transferring tube and method for manufacturing heat transferring tube - Google Patents

Abstract

PURPOSE:To improve the efficiency of gasification and the efficiency of condensation by a method wherein an inner surface of a metallic pipe is provided with some projections, fins and sub-grooves, the opening width of a main groove between each of the projections is narrowed and formed as a tube part. CONSTITUTION:After on an inner surface of metallic pipe 1 some parallel projections 2 and fins 3 are helically formed at a specified angle in respect to its axial direction, some parallel sub-grooves 5 forming a specified angle are formed on them. Each of the projections 2 is deformed from the center line of the sub-groove 5 toward both sides at a part where each of the projections 2 is crossed with the sub-groove 5. With such an arrangement, the opening width of a main groove 4 between each of the projections 2 is narrowed at a part between each of the sub-grooves 5 so as to form a tubular part 6 having a fine opening. As a result, of the heat transferring tube is used at an evaporating part of a heat exchanger, some air bubbles may easily be formed at an inside part, an evaporation of the thermal medium is promoted and the efficiency of gasification is improved. When the tube is used as a condensing tube, even if the surface of the each of the projections is covered by a thin layer of condensed liquid by a surface tension, each of the fin extremity ends is kept at its exposed state and a heat exchanging efficiency with a thermal medium vapor is kept high, resulting in that a condensing efficiency can also be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of Industry-1-1 The present invention relates to a heat transfer tube used as an evaporation tube, condensation tube, heat vibrator, etc. of a heat exchanger, and a method for manufacturing the same.

``Prior art'' Conventionally, saw heat transfer tubes have been known in which many spiral or linear grooves are formed on the inner surface of a tube body made of copper or the like by rolling or drawing. The following effects can be obtained by forming the funnel.

■ When this heat transfer tube is used as a condensing tube, the heat medium vapor flowing inside the condensing tube is made into a turbulent flow by the ridges between the grooves, and the ridges serve as condensation nuclei to increase the condensation effect of the heat medium vapor. enhance and promote liquefaction.

Furthermore, the condensed heat transfer liquid is efficiently flowed in the longitudinal direction of the heat transfer tube due to the surface tension within the grooves, increasing the reflux effect.

■ When used as an evaporator tube, the edges of the evaporator tube become evaporation nuclei for generating bubbles, promoting boiling (7
As a result, the vaporization efficiency of the heat medium liquid supplied into the heat transfer tubes is improved.

In addition, due to the surface forces in the ocean, the heat transfer liquid flows in the longitudinal direction of the heat transfer tube and is uniformly dispersed on the inner surface of the heat transfer tube.

I-Problems to be solved by the invention jBy the way, in order to improve the performance of such a groove I-1 heat exchanger tube, if+
It is thought that it is effective to have the opening [1 width in between and the near side (-) in a tubular shape.

This,]-eel tubular if/? According to, for example, when used as an evaporation tube, air bubbles are generated inside the groove, and these air bubbles act as nuclei and promote the evaporation of the heat medium, further increasing the vaporization efficiency. Since the surface tension within the stone filter 11-1 is improved, the transport efficiency of the heat medium increases, and the overall heat transfer performance is expected to improve. In heat exchanger tubes, the opening width of the groove must be larger than the width of the bottom due to processing constraints, so it is impossible to form iM' into a tubular shape.
At 1J capacity, there was a limit to the improvement of heat transfer performance.

Therefore, the present invention contemplates a transmission method using the following manufacturing method.
He invented a tube. This method (':J, by forming a large number of two types of γt1\ that intersect with each other on the surface of a single plate strip), the width of the IIRJD of the groove formed earlier can be adjusted to Both sides are narrowed to form a tubular part. Next, this metal plate strip is rolled with the liI circle forming surface inside (straightened), and the abutted edges are welded using an electric resistance welding tube method to obtain a heat transfer tube.

In the thus obtained heat transfer tube, the width (the opening U of each first groove formed on the inner surface of the J1 metal tube) is narrowed at the intersection with the second d temple, so that it becomes a narrow tubular shape with a width of 1. Department,
A large number of such tubular portions are formed at intervals in the longitudinal direction of the first groove.

Therefore, air bubbles are likely to form inside these tubular parts.
The bubbles act as a core and promote the evaporation of the heat medium, increasing the evaporation efficiency. Furthermore, since the surface tension within the tubular portion is improved, the transport efficiency of the heat medium is increased, and the overall heat transfer performance is improved.

However, although heat transfer tubes have an excellent evaporation promoting effect when used as evaporation tubes as described in 1.1, when used with condensation tubes instead of evaporation tubes, production = 1 stroke. The condensation efficiency (liquefaction efficiency) of the heat medium is relatively low, and
P Lack of advantage over heat exchanger tubes with pure spiral grooves1
．． It turned out that it was.

The Ministry of Invention and others investigated the cause and found that the heat transfer tube was used as a condensing tube, and the heat medium condensed due to the excellent surface tension of the intersecting grooves formed throughout the inner surface. The condensate generated by this process spreads into the container on the inner surface of the heat exchanger tube, and the entire inner surface of the heat exchanger tube is covered with a thin liquid film. For this reason,
It was found that the contact area between the metal surface and the heat medium vapor decreases, the heat transfer efficiency from the heat medium vapor to the metal surface decreases significantly, and the condensation efficiency of the heat medium vapor decreases1. Means for Accomplishing 1 The present invention has been made to solve the problems set forth in -.
On the inner circumferential surface of the metal tube, there are a number of parallel protrusions extending in a direction oblique to the axis of the metal tube and having a rectangular cross section (1) γf standing up from the inner surface of the metal tube ( 7. A number of fins extending parallel to the protrusions, and a number of 12 rows intersecting the protrusions and fins at a constant angle (sub) 1! r
are formed, and each protrusion is deformed from the center line of each sub-groove to both sides at the intersection of each protrusion and each sub-groove, thereby creating an opening in the upper groove between each protrusion. The width is narrowed and each part is tubular.

Note that it is desirable that the tip of the fin No. 11 has an acute-angled cross section.

Further, the protruding teeth of the fins from the inner surface of the metal tube may also be small.

- On the other hand, the manufacturing method of the present invention includes a number of parallel protrusions having a rectangular cross section and fins parallel to these protrusions and narrower than the protrusions on the surface of the metal plate strip 10A having a constant width. By rolling and forming a large number of parallel sub-grooves that intersect these protrusions and fins at a certain angle, the tip of each protrusion is moved away from the center line of the sub-groove at the part where it intersects with these sub-grooves. After deforming to both sides and relatively narrowing the width of the subcontract ν between each protrusion at these deformed parts, the plate material is shaped into a tubular shape with this ii+1' forming surface facing inward. It is characterized by the fact that it is rolled up and placed onboard an ERW ship, and the heat exchanger tube is formed with a 4-inch diameter.

Mmm. It is preferable that the sub-grooves have a cross section shaped like a letter 3.
, Yoso, the slight intersection of the two ridges and the sub'ri has a degree of ffJ of 20 to 6
It is desirable that the angle is 0°.

(-Function-1) In the vine heat exchanger tube according to the present invention, a large number of tubular portions whose opening width is narrower than the inner width of the main groove 114 are formed at intervals in the longitudinal direction of each main groove. When this heat transfer tube is used in the evaporation part of a heat exchanger etc. (1), bubbles are likely to be generated inside each tubular part, and these bubbles become the evaporation part and promote the evaporation of the heat medium. The vaporization effect (is greatly increased).

In addition, according to this heat transfer tube, the heat medium liquid flowing into each #:, ii'lt is quickly transported along the main groove by capillary phenomenon into the tubular part (J). The transport efficiency of the heat medium is also improved compared to the case of a heat exchanger tube with simple grooves formed therein.

On the other hand, when this heat transfer tube is used as a condensing tube of a heat exchanger, the grooves between each protrusion are filled with liquid due to two series of surface tensions, and the surface of each protrusion is filled with condensate. Even if the heat transfer tube is covered with a thin layer of water, the tip of each fin that rises from the inner surface of the heat transfer tube can drain easily.
Therefore, the metal surface is kept exposed at the tips of these fins, and the heat exchange rate with the heat medium vapor is maintained high, resulting in a higher condensation efficiency than the conventional simple W/7 (ζj heat transfer tube). can also be significantly increased.

On the other hand, according to the method for manufacturing a heat exchanger tube according to the present invention, the above-mentioned heat exchanger tube, which has been difficult to manufacture in the past, can be easily manufactured. Furthermore, by continuously performing the two steps of rolling and electric resistance welding, long heat exchanger tubes can be manufactured continuously and efficiently, making it suitable for mass production and reducing manufacturing costs.

"Example" Next, 1. With reference to FIG. 15, an embodiment of the heat exchanger tube according to the present invention will be described in detail.

As shown in FIGS. 1 and 2, the heat transfer tube of this embodiment has a spiral shape formed at a constant angle to U7 in the axial direction of the metal tube 1 on the inner surface of the metal tube I having a circular cross section. After forming a large number of parallel protrusions 2 and fins 3 in ski rows, a large number of parallel sub-grooves 5 forming a constant angle with these protrusions 2 and fins 3 are formed on the edges of the protrusions 2 and fins 3. 3. The intervals between the protrusions 2 are all equal as shown in Figure 1, and three or one fin is formed for each of the plurality of protrusions 2 (three in the figure). .

As shown in FIGS. 2 to 7, each protrusion 2 and sub i? 4' and 5, each protrusion 2 is deformed from the center line of the sub-groove 5 to both sides.

As a result, the opening width of the main groove 4 between each of the protrusions 2 is narrowed in the portion between each side 5, forming a tubular portion 6 having a narrow opening.

The metal tube 1 is formed from conventionally used +1i materials such as copper, copper alloy, and aluminum, and its wall thickness, diameter, etc. are determined depending on the application. Further, on the inner surface of one circumferential portion of the metal tube I, a flat band-shaped welded portion IA extending in the axial direction is formed.

The cross-sectional shape of the protrusion 2 is rectangular before being deformed by the sub-groove 5, as shown in FIG. But -7, protrusion 2
The upper groove 4 formed between them has a U-shaped cross section (the cross-sectional angle of the bottom portion is close to a right angle).

In this way, the closer the U-shape is, the easier it is to narrow the opening width of the main groove 4 and form it into a tubular shape.

The inner width W1 of the main 7144 is 40 to 140% of the depth T11,
If it is less than 3.40%, which is preferably 80 to 120,
The main groove 4 is likely to collapse when forming the sub-groove 5, and machining is also difficult. It is impossible for humans to narrow the opening width of the tubular portion 6 by more than 140%.

In addition, the interval P1 between the main grooves 4 is 1.5 to 3 times the inner width W1,
Desirably it is 18 to 22 times. If it is less than 15 times, the protrusions 2 will fall down when the sub-grooves 5 are formed, making it difficult to form the tubular portions 6. If it is larger than 3 times (J main W + ¥4) the formation density becomes smaller and the effect of improving heat transfer performance is reduced.

Specifically, in the case of a normal heat exchanger tube, the depth I (l
= 0, 2~0, 3t+x, inner width W+, = 0.2
-0, 5 m7I, P I-0, 4~], 5m7
I. The appropriate cross-sectional angle of the bottom is about 75° or more.

The cross-sectional shape of the fin 3 before deformation is an acute isosceles triangular shape, and the width is narrower than the protrusion 2, and the tips i and Vj are pointed, and the 3° fin 3 stands upright from the inner surface of the metal tube 1. Height before deformation T-(211, height 'i-11 of protrusion 2 50
It is desirable that it be about ~90%.If it is less than 4.50%, liquid drainage will deteriorate, resulting in a decrease in condensation efficiency, and if it is more than 90%, it will be difficult to manufacture. Further, it is desirable that the bottom width of the fin 3 has a width of L11 so that the fin 3 is not damaged when it is deformed by R5.

Specifically, in the case of a normal heat exchanger tube, the height is I-1201~
In addition, the distance W3 from the protrusion 2 is determined by the inner width W of the main 'ti+'j 4 in order to improve the drainage of condensate from the fin 3. I hope it's bigger than + (7).

On the other hand, the sub-groove 5 is formed to have a V-shaped cross section.

The interval P2 between the sub-grooves 5 may be equal to that of the upper groove 4, as shown in FIG. 11, but does not necessarily have to be equal to the main if+¥4.

The width W4 of the minor groove 5 is 10 to 90 of the width W2 of the main groove 4.
%, preferably i:j: 50-70% 3,
If it is less than 10%, the width W2 of the main groove 4 can be sufficiently narrowed to 1゛, and if it is less than 90%, the opening of the main groove 4
iN [There is a risk that one copy may be closed.

In addition, the depth D of the sub-groove 5 is the height of the protrusion 2 ((50~
100%, preferably il, 180-100%. If it is less than 50%, the opening width of the main groove 4 may be sufficiently narrowed, but if it is less than 100%, there is a risk that the main groove 4 may close and become 12.

Specifically, in the case of a normal heat exchanger tube, the depth of the sub-groove 5 I) ~
0. I5~0, 3 vtm, interval 1) 2 = 0
, 4~15Z m, V-shaped cross-sectional angle 1; I: 4.5~
Approximately 90' is suitable.

Note that the intersection angle α between the main 'tR4 and the minor groove 5 is 20 to 60.
°, especially preferably 30 to 40 °, preferably 1 ° to 20 °
Outside the 60° range, it becomes difficult to form the tubular portion 6. Further, it is desirable that the main groove 4 is within 30° relative to the axial direction of the metal tube 1. As a result, the flow of the heat medium liquid in the axial direction of the metal tube 1 becomes worse.

By forming the sub'rM 5 as described in -1-1, the minimum width [] of the tubular portion 6 is 75% of the inner width W1 of the main groove 4.
% or less. 75%, the bubble generation effect is reduced, and the heat transfer performance improvement effect is reduced compared to the conventional grooved heat transfer tube.

Next, a method for manufacturing this heat exchanger tube will be explained. First, as shown in FIG.
The ridge 2 and the fin 3 are connected by the 10th rule R1, and the 20th
- The sub-grooves 5 are sequentially formed by the rule R2.

On the outer circumferential surface of the tenth rule R1, as shown in FIG.
, V iM I for forming OA and fin 3
A large number of IAs are formed parallel to each other at a constant angle inclination in the circumferential direction of the node I'21.
As shown in FIG. 11, protrusions 2 and fins 3 are formed on the surface of the plate material 1 from r, ″3, with the protrusions 2 and fins 3 being formed at an angle with respect to the longitudinal direction. A large number of protrusions I2 having a V-shaped cross section are formed parallel to each other on the surface as shown in FIG. The main groove 4 is formed in the plate strip 1 in the opposite direction to the groove R1, as shown in Fig. 11.
A large number of parallel sub-grooves 5 having a V-shaped cross section are formed, intersecting the fins 3 at a constant angle α.

In addition, between the protrusions 12 of the second [7-ru I (2), the first
0 In Figure - It may be curved as shown by the dotted chain line 14 4
．． By doing this, when forming the minor groove, the main i
The side wall portion of i't4 deforms smoothly, increasing the effect of narrowing the width of the opening t1 of the main 'rtI\4. Further, a flat part (with a narrow width) may be formed at the tip of each protruding part I2 as shown in Hakama No. 13.

After the rolling is completed, the plate strip 1 is introduced into the electric resistance welding machine with the grooved surface facing the inner surface (J), and the plate strip 1 is passed through the forming roll 1111 in multiple stages (7). Finally, both side edges of the strip material 1 are welded to form a round tube in the width direction.

``1j sewing device δ1 may be one that is commonly used.''] 8) The hem stitching conditions may also be the same as those for normal processing. After that, the welded part on the outer circumferential surface of the pipe is shaped as necessary, and the
Roll it up into a knot shape or cut it to a predetermined length to obtain a long heat exchanger tube.

According to the heat exchanger tube consisting of two legs, each main groove 4 is intermittently spaced in the longitudinal direction (the opening [-] width is 'Ifi').
; is formed with a large number of tubular portions 6 that are relatively narrow compared to the inner width W+ of the heat exchanger tube as shown in FIG. Compared to the case of a heat exchanger tube with a smooth inner surface or the case of a heat exchanger tube as shown in FIG. 17, each tubular part 6 is
When air bubbles are generated inside the liquid, these air bubbles act as nuclei and promote evaporation, and the vaporization efficiency of the heat transfer liquid (for example, L) is greatly increased.

Furthermore, since the tubular portions 6 are disposed intermittently, the heat medium liquid that has flowed into each main groove 4 is subjected to surface tension from the inward direction of the tubular portion 6, and is caused to flow along the main groove 4 due to the capillary phenomenon. Please transport it promptly. Therefore, the transport efficiency of the heat transfer liquid is Qi
Compared to the case of pure grooved heat exchanger tubes, the

On the other hand, when this heat transfer tube is used as a condensing tube of a heat exchanger (7), as shown in Fig. Even if the strip 2 is covered with a thin JI!i of condensed liquid (7), the tip of each fin 3 that stands up from the inner surface of the heat transfer tube protrudes from the surface of the liquid because it drains easily. Therefore, the tip of each fin 3 Since the J metal surface is kept exposed and the heat exchange rate with the heat medium vapor is maintained high, the condensation efficiency is also significantly higher than that of the conventional marked line heat exchanger tube. It is possible to increase it.

In addition, the inner area of the heat exchanger tube is larger than that of an Ilt pure groove (-=I) heat exchanger tube, and the edges of the protrusions 2 and fins 3 are sharp, so the activity is high. This also promotes condensation of heat medium vapor and increases liquefaction efficiency3.
Furthermore, in the above manufacturing method, by consecutively performing the two steps of rolling and electric resistance welding, a long and small diameter heat exchanger tube can be efficiently obtained, mass production is possible, and manufacturing costs are reduced. What benefits can you have?

In the embodiment 1'', the shape of the heat exchanger tube was circular in cross section, but the present invention is limited to a circular cross section, but it is also possible to implement the tube in an elliptical cross section, a flat tubular shape, etc.

Further, in the above embodiment, the plate material I having the width of one heat exchanger tube was used, but instead, after forming the protrusions 2, fins 3, and sub-grooves 5 on a sufficiently wide plate material +4, In the slitter (
1. Cut the strips into narrow strips using J and apply electric resistance welding to these strips to form heat exchanger tubes. But that's fine.

In that case, productivity can be greatly improved.

In addition, cooling fins are provided on the outer peripheral surface of the heat transfer tube of the present invention.
](-), make insertion holes in each cooling fin, pass the heat transfer tubes through these holes, and then insert a plaque inside the heat transfer tube to enlarge the outer diameter of the heat transfer tube. All you have to do is fix the cooling fins to the heat tube.

In this case, as shown in FIG. 20, if the amount of protrusion of the fins 3 from the inner surface of the metal tube l is made slightly smaller than the amount of protrusion of the protrusions 2, the fins do not need to come into contact with the tube expansion plaque.

In addition, the expansion h1 of the heat transfer tube by plaque is preferably 10% or more of the outer diameter of the pA tube. < iJ: It is desirable to set it to 7% or more F1). If the tube expansion exceeds 10%, the tubular portion 6 may close and the evaporation efficiency may decrease.

By carrying out such pipe expansion processing, as shown in FIG.
The width of the tubular portion 6 of the main groove 4 is further narrowed, making it possible to make the tubular portion 6 more similar to a tubular shape, promoting the above-mentioned bubble formation effect and improving evaporation efficiency.

It can be planned.

"Effects of the Invention" As explained above, in the heat exchanger tube according to the present invention, there are many tubular portions in which the opening width is narrower than the inner width of the upper groove, with gaps in the longitudinal direction of each city. Therefore, when heat exchanger tubes are used in the evaporation section of a heat exchanger, air bubbles are generated inside each tubular section, and these bubbles become the evaporation section and cause the heat medium to evaporate. It promotes evaporation and greatly increases vaporization efficiency.

In addition, according to this heat transfer tube, the heat medium liquid that has flowed into each main groove is caused by the capillary phenomenon within the tubular portion to the main dI
Since it is quickly transported by '/I+'f, j, lG
Compared to the case of a heat exchanger tube with pure grooves formed therein, the heat medium transport efficiency is improved by 6.

-, this heat transfer tube is used with the condensing tube of the heat exchanger and 7 (
, the upper groove between each protrusion is filled with liquid due to the above-mentioned surface I horsepower, and the surface of each protrusion is covered with a thin layer of condensate (9, heat transfer tube). The tip of each fin that stands up from the inner surface protrudes from the surface of the condensate because it drains well.1-2 Therefore, at the tips of these fins, the metal surface is kept in a state of being produced, and there is no contact with the heat medium vapor. High heat exchange rate
1), it is possible to greatly increase the condensing efficiency>p compared to the conventional pure gold heat exchanger tube.

On the other hand, according to the method for manufacturing a heat exchanger tube according to the present invention, it is possible to produce a heat exchanger tube as described in 1if7, which was previously difficult to manufacture. 3. Heat exchanger tubes can be manufactured easily. In addition, by continuously performing the rolling process and the electric resistance welding process, long heat exchanger tubes can be manufactured continuously and efficiently, making it suitable for mass production and reducing manufacturing costs. It has the advantage of being able to

[Brief explanation of the drawing]

Fig. 1 is a diagram of an embodiment of the heat exchanger tube according to the present invention, Fig. 2 is an enlarged view of the inner surface of the heat exchanger tube, and Figs. 3 to 7 are In-ITJ to ■-■l lines. Viewed line diagram Cross section diagram (
An explanatory diagram showing the manufacturing method of J-shaped heat transfer tubes, Fig. 9 is similar to Fig. 10-
FIG. 10 is an explanatory diagram showing a cross section of the 20-ru tube, and FIGS. 16 figures 1. Fig. 19 is an explanatory diagram showing the effect of the present invention, and Fig. 20 is an enlarged cross-sectional view showing the state in which the heat exchanger tube is expanded in diameter. 1. Metal tube, 1△ welded part, 2. Protrusion , 3 fin, 4
Main groove, 5 Minor groove, 6 Tubular part, R1 10th line, R2 20th line, I7 Condensate.

Claims (6)

[Claims] (1) On the inner circumferential surface of the metal tube, a large number of parallel protrusions extending in a direction oblique to the axis of the metal tube and having a substantially rectangular cross section, and erecting from the inner surface of the metal tube, Fins extending parallel to the protrusions and a large number of parallel sub-grooves intersecting the protrusions and the fins at a certain angle are formed, and each protrusion is formed at the intersection of each protrusion and each sub-groove. is deformed from the center line of each sub-groove to both sides, thereby narrowing the opening width of the main groove between each of the protrusions to form a tubular portion. (2) The heat exchanger tube according to claim 1, wherein the tip of the fin is formed to have an acutely pointed cross section. (3) The amount of protrusion of the fins from the inner surface of the metal tube is:
The heat exchanger tube according to claim 1 or 2, characterized in that the amount of protrusion is smaller than the amount of protrusion of the protrusion. (4) A large number of parallel protrusions with a rectangular cross section and fins parallel to these protrusions and narrower than the protrusions are formed by rolling on the surface of a metal plate strip of a constant width, and these protrusions and fins are formed by rolling. By rolling a large number of parallel sub-grooves that intersect with the sub-grooves at a certain angle, the tip of each protrusion is deformed from the center line of the sub-groove to both sides at the portions that intersect with these sub-grooves. After relatively narrowing the opening width of the main groove at these deformed parts, with the groove forming surface facing inward, the plate material is rolled into a tubular shape and subjected to electric resistance welding to form a heat exchanger tube. A method for manufacturing a heat exchanger tube, characterized in that: (5) The method for manufacturing a heat exchanger tube according to claim 4, wherein the sub-groove is formed to have a V-shaped cross section. (6) The method for manufacturing a heat exchanger tube according to claim 4 or 5, wherein the intersecting angle between the protrusions and the sub-grooves is 20 to 60 degrees.