JPH0724522A - Heat-transfer tube for absorber and production therefor - Google Patents

Abstract

PURPOSE:To drastically improve the heat exchanger efficiency of a heat-transfer tube by forming many fine grooves extending in the longitudinal direction of the tube on the outer peripheral surface of the tube in the root parts of curved grooves. CONSTITUTION:Plural crest parts 12 and plural root parts 14 are formed alternately and curvedly in the peripheral direction of the heat-transfer tube 10 for an absorber. Plural lines of curved grooves 15 extending in the longitudinal direction of the tube are formed by those crest parts 12 and root parts 14. Many fine grooves 16 extending in the direction of the tube axis along the root parts 14 are formed in the root part of each curved groove 15. The fine grooves are formed by the groove depth and pitch smaller than those of each curved groove 15. The root parts 14 and the crest parts 12 are formed alternately in the die hole to form the heat-transfer tube 10 and a split die where irregular lines are formed on the crest parts is used. In this way, the heat transfer tube having an excellent heat exchanger efficiency can be manufactured easily.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heat transfer tube for an absorber which is installed in an absorber such as an absorption refrigerator or an absorption heat pump, and a manufacturing method thereof, and a heat transfer tube for an absorber having particularly excellent heat exchange efficiency, The present invention relates to a method capable of easily and continuously producing such a heat transfer tube for an absorber.

[0002]

BACKGROUND ART Generally, a smooth tube having a circular cross-section with a smooth inner and outer surface is adopted as a heat transfer tube used in an absorber such as the absorption refrigerator or the absorption heat pump. However, since the smooth tube has low heat transfer performance, it has been difficult to meet the demand for higher performance and smaller size of the absorber. Also,
In such a smooth pipe, the width of the absorbing liquid that flows down the pipe outer circumferential surface in the pipe circumferential direction becomes narrower as it goes downward due to surface tension, so a wet area where an effective heat exchange action is exhibited is secured. In addition to being difficult to be done, there is also a problem that a thirst surface is likely to occur on the outer surface of the tube, and LiBr and the like in the absorption liquid precipitates at this thirst surface, and the water vapor absorption rate of the absorption liquid, and consequently the heat transfer performance, deteriorate. .

Therefore, the applicant of the present invention previously filed Japanese Patent Application No. 63-63.
-330709 (Japanese Patent Laid-Open No. 2-176378) and the like, a plurality of peaks and troughs extending in the longitudinal direction on the outer surface of the tube are alternately formed with a cross-sectional shape curved in the circumferential direction of the tube. We proposed a heat transfer tube for an absorber that has a plurality of curved grooves extending in the same direction.

In a heat transfer tube having such a curved groove, when it is used by arranging in a horizontal direction, when the absorbing liquid dropped or sprinkled on the outer surface of the tube flows down in the pipe circumferential direction, the inclination angle changes, etc. As a result, the disturbing phenomenon can be effectively induced in the absorbing liquid, and the high concentration portion of the absorbing liquid is well exposed to the outer surface, so that the absorbing action of water vapor, that is, the heat transfer performance is improved. In addition, since the absorbing liquid stays in the curved groove and is guided in the pipe longitudinal direction, the wetted area can be expanded and the dry surface can be reduced.

However, even with a heat transfer tube having a curved groove formed of such peaks and valleys, the required improvement in heat transfer performance and expansion of the wetted area may not be sufficiently achieved. Therefore, further improvement of heat transfer performance and expansion of wetted area were required.

Further, the heat transfer tube having the curved groove as described above is generally formed by plastically deforming the tube wall of the tubular material in the drawing process, but in the drawing process using a general die, the curve is formed. Since the groove is formed continuously over the entire length of the tubular material, it is extremely difficult to partially form the curved groove.

That is, both ends of the heat transfer tube of the absorber are connected to the flow port of the cooling medium provided in the tube plate of the absorber, and the baffle plate is attached to and supported by the intermediate portion thereof. Since it is attached to the absorber, it is desirable to provide smooth tubular portions without curved grooves at predetermined positions on both ends and the intermediate portion of the heat transfer tube, but with conventional drawing processing, curved groove formation is performed. It was extremely difficult to alternately form the portions and the unformed portions in the tube axis direction.

[0008]

The present invention has been made in view of the circumstances as described above, and the problem to be solved by the present invention is that the disturbing action or the like on the absorbing liquid flowing down the outer peripheral surface of the pipe is more effective. Another object of the present invention is to provide a heat transfer tube for an absorber in which the heat transfer performance is further improved.

Further, the present invention also provides a heat transfer tube for an absorber, in which the absorbing liquid flowing down the outer peripheral surface of the tube is advantageously spread in the longitudinal direction of the tube, and the wetted area is further expanded.
To aim.

Further, according to the present invention, when the absorber heat transfer tube having the curved groove extending in the longitudinal direction of the tube, which has improved heat transfer performance and expanded wetted area, is manufactured by the drawing process, the curved groove is used. It is another object of the present invention to provide a method for manufacturing a heat transfer tube for an absorber, which is capable of alternately forming the formed portion and the unformed portion in the tube axis direction.

Further, according to the present invention, when a heat transfer tube for an absorber having a curved groove extending in the longitudinal direction of the tube, which has improved heat transfer performance and expanded wetted area, is manufactured by a drawing process, the curved groove is used. It is also possible to provide a method for manufacturing a heat transfer tube for an absorber, which can continuously form a formed portion and an unformed portion, and can also continuously perform drawing using a coiled continuous pipe material as a raw material. To aim.

[0012]

In order to solve such a problem, according to the present invention, a heat transfer tube for an absorber, in which an absorbing liquid is brought into contact with an outer peripheral surface of a tube and a cooling medium is circulated in the tube, The peaks and troughs of the cross-sectional shape are alternately provided in the pipe circumferential direction to form a plurality of curved grooves extending in the pipe longitudinal direction, and along the troughs on the pipe outer peripheral surface of the troughs of the curved grooves. The heat transfer tube for an absorber having a large number of fine grooves extending in the longitudinal direction of the tube is featured.

Further, according to the present invention, peaks and valleys having a curved cross-sectional shape are alternately provided in the pipe circumferential direction to form a plurality of curved grooves extending in the longitudinal direction of the pipe, and the pipes at the valleys of the curved grooves are formed. When manufacturing a heat transfer tube for an absorber, in which a large number of fine grooves extending in the tube longitudinal direction along the valley are formed on the outer peripheral surface,
It is divided in the circumferential direction so that it can be opened and closed by advancing and retracting in the direction perpendicular to the central axis, and valleys and peaks with a curved cross-section are formed alternately in the circumferential direction on the inner surface of the die hole. On the surface of, by using a dividing die in which a large number of fine uneven lines extending along the mountain portion are formed, a predetermined tubular material is subjected to a drawing process, and by opening and closing the dividing die at the time of the drawing process, The absorber transmission for forming the curved groove forming portion where the curved groove and the fine groove are formed on the outer peripheral surface of the tube and the curved groove unformed portion where the curved groove and the fine groove are not formed alternately in the pipe axis direction. The method of manufacturing the heat tube is also a feature thereof.

[0014]

In the heat transfer tube for the absorber having the structure according to the present invention, since the bottom of the curved groove is made uneven by the fine grooves, it is possible to prevent the absorption liquid flowing down in the pipe circumferential direction. The disturbing effect of the curved groove is more effectively exerted.

Further, in such a heat transfer tube for an absorber,
In addition to the expansion action in the pipe axis direction due to the retention in the curved groove, the absorption liquid flowing down in the pipe circumferential direction also has the expansion action in the pipe axis direction due to the capillary effect of the fine grooves. Affected.

Therefore, in the heat transfer tube for an absorber having the structure according to the present invention, the water vapor generated by exposing the outer surface of the portion having a high concentration of the absorbing liquid due to the disturbing action of the curved groove and the fine groove. The heat exchange efficiency of the heat transfer tube is dramatically improved by synergistically exerting the effect of improving the absorption effect and the effect of increasing the wetted area of the heat transfer tube due to the expansion effect of the curved groove and the fine groove. .

Further, in the method for manufacturing a heat transfer tube for an absorber according to the present invention, when the tubular material is drawn,
A plurality of curved grooves extending in the pipe longitudinal direction are formed by the valleys and ridges formed on the inner surface of the die hole, and a large number of grooves extending along the curved grooves are formed by the uneven lines formed on the surface of the ridges. Fine grooves are formed simultaneously with the curved grooves.

Moreover, in the method of manufacturing the heat transfer tube for an absorber, the inner surface of the die hole is brought into contact with the outer peripheral surface of the tubular material by closing the split die during the drawing process, so that the inner surface of the die hole is brought into contact with the inner surface of the die hole. The formed troughs, peaks, and uneven lines form curved grooves and fine grooves on the outer peripheral surface of the tubular material, while opening the split die separates the inner surface of the die hole from the outer peripheral surface of the tubular material. As a result, the curved groove and the fine groove are not formed.

Therefore, in the method of manufacturing a heat transfer tube for an absorber according to the present invention, the curved groove and the fine groove are simultaneously formed by the drawing process using the same die, which is disclosed in the above-mentioned Japanese Patent Laid-Open No. 2-176378. It is possible to easily manufacture a heat transfer tube having a curved groove and a fine groove and having excellent heat exchange efficiency without basically modifying a conventional heat transfer tube manufacturing line having a curved groove.

Moreover, in the method of manufacturing the heat transfer tube for the absorber, the split dies are opened / closed during the drawing process to thereby form the curved groove forming portion in which the curved grooves and the fine grooves are formed without interrupting the drawing process. The curved groove and the curved groove non-formed portion in which the fine groove is not formed can be continuously formed alternately at arbitrary intervals in the tube axis direction.

Further, in the method of manufacturing the heat transfer tube for the absorber, since the curved groove forming portion and the non-forming groove portion can be continuously formed, the curved groove processing is continuously performed using the coiled continuous pipe material as a raw material. It is also possible to carry out the process in a targeted manner, whereby a significant improvement in the processing efficiency is achieved as compared with the case where the pipe material is processed one by one.

[0022]

EXAMPLES Examples of the present invention will now be described in detail with reference to the drawings in order to clarify the present invention more specifically.

First, FIG. 1 shows a sectional view of a heat transfer tube 10 for an absorber which is an embodiment of the present invention, and FIG. 2 shows a side view thereof. In the heat transfer tube 10, peak portions 12 and valley portions 14 are alternately arranged in the circumferential direction of the tube.
A plurality of curves are formed. And those Yamabe 12
The valleys 14 form a plurality of curved grooves 15 extending in the pipe longitudinal direction.

In this embodiment, 12 peaks 12 and 12 valleys are formed at substantially equal intervals in the circumferential direction, so that the 12 curved grooves 15 are parallel to the tube axis direction. And is formed linearly.

By the way, the depth of the curved groove 15: d '
The specific dimensions such as the pitch and the pitch: p ′ are not particularly limited, but if the depth of the curved groove 15: d ′ or the ratio of the depth to the pitch: d ′ / p ′ is too small, An effective disturbing effect is less likely to be exerted on the absorbing liquid flowing down the outer peripheral surface of the pipe, and the depth of the curved groove 15 is d'or the ratio of the depth to the pitch is d '/ p'. Big,
The cross-sectional area of the pipeline decreases and the head loss increases.

Therefore, in order to obtain effective heat transfer performance,
The depth of the curved groove 15: d ′ is 0.1 mm to 1.0 mm
And the ratio of the depth of the curved groove 15 to the pitch:
It is desirable that d '/ p' be 0.01 to 0.5.

Further, on the outer peripheral surface of the heat transfer tube 10,
As shown in FIG. 3, a large number of fine grooves 16 extending in the tube axis direction along the valleys 14 are formed at the bottom of each curved groove 15. These fine grooves 16 are formed with a groove depth: d and a pitch: p smaller than the curved groove 15 formed by the peaks 12 and the valleys 14.

In this embodiment, five fine grooves 16 are formed on the outer peripheral surface of each valley 14.

Here, in the fine groove 16, if the groove depth: d is too shallow, it is difficult to effectively obtain the desired effect of increasing the wetted area, and if it is too deep, the coefficient of friction during processing becomes small. It becomes large and difficult to process. Therefore, it is desirable that the depth d of the fine groove 16 be set so as to satisfy the following (formula 1). 0.02mm ≤ d ≤ 0.2mm (Equation 1)

Further, if the circumferential pitch: p of the fine grooves 16 is too small, it is difficult to effectively obtain the desired effect of increasing the wetted area, and if it is too large, the effect of providing the fine grooves is small. Become. Therefore, it is desirable to set the pitch p of the fine grooves 16 so as to satisfy the following (formula 2). 0.1 mm ≤ p ≤ 1.0 mm (Equation 2)

The cross-sectional shape of the fine groove 16 is not particularly limited, but in the present embodiment, an upward arc-shaped portion and a downward arc-shaped portion having substantially the same radius of curvature are circumferentially formed. Is formed in a corrugated plate shape continuously.

The width in the tube circumferential direction of the portion where the fine grooves 16 are formed on the outer peripheral surface of the heat transfer tube 10 is not particularly limited, but generally, the outer peripheral surface of the mountain portion 12 is a smooth surface.
The width in the pipe circumferential direction and the width in the pipe circumferential direction of the valley portion 14 in which the fine grooves 16 are formed on the outer peripheral surface are set to be substantially the same.

In the heat transfer tube 10 having such a structure, the curved groove 15 allows the absorbing liquid to flow down in the circumferential direction of the pipe to be retained therein, so that a predetermined liquid depth is formed in the curved groove 15. , Is advantageously guided and expanded in the axial direction of the tube.

The absorbing liquid is spread in the axial direction of the pipe by the staying action of the curved groove 15 and then is made to flow down in the circumferential direction of the pipe. Since the inclination angle at is changed by the curved groove 15, effective disturbance and convection phenomenon are caused to the absorbing liquid flowing down in the pipe circumferential direction, and the portion where the concentration of the absorbing liquid is high is the outer surface. The water vapor is effectively exposed to the water, and the absorption effect of water vapor is improved.

Moreover, the heat transfer tube 10 has a curved groove 1
5, a large number of fine grooves 16 extending in the tube axis direction
Is formed so that the absorbing liquid flowing down the outer peripheral surface of the pipe flows down the fine grooves 16 in the circumferential direction of the pipe, and at that time, the absorption liquid entering the fine grooves 16 is absorbed. The liquid is guided and spread in the tube axis direction by the fine grooves 16. That is, the fine groove 16 is
Since it is formed with a small groove width, the fine groove 1
The absorbing liquid that has entered the microscopic groove 6 is caused by the action of capillarity based on the surface tension (surface force or interfacial force).
The inside of 6 is guided in the tube axis direction.

Therefore, in the heat transfer tube 10 having the curved grooves 15 and the fine grooves 16 as described above, the absorbing liquid flowing down the outer peripheral surface of the tube by the curved grooves 15 and the fine grooves 16 in the tube axial direction. Since it is advantageously spread, a wetted area where a heat exchange action is exhibited can be sufficiently secured, and a dry surface on the outer surface of the tube can be prevented, so that LiB can be prevented.
The decrease in the water vapor absorption rate due to the precipitation of r can be effectively eliminated. The expansion action of the absorbing liquid in the pipe axial direction by the curved groove 15 is effective mainly in the region where the liquid film thickness is relatively large in the upper portion of the heat transfer pipe, and the expansion action of the absorbing liquid in the pipe axial direction by the fine grooves 16 is effective. Is considered to be effective mainly in the region where the liquid film thickness is relatively small below the heat transfer tube.

Therefore, in the heat transfer tube 10, therefore, the effect of improving the absorbing action of water vapor due to the disturbing action exerted on the absorbing liquid by the curved groove 15 and the absorbing liquid by the curved groove 15 and the fine groove 16 are exerted. The effect of increasing the wetting area based on the expanding action in the tube axis direction is synergistically exerted, whereby the heat exchange efficiency is dramatically improved.

Moreover, the outer surface of the curved groove 15 at the valley portion is
Since it is made uneven by the fine grooves 16, it can exert a more effective disturbing action on the absorbing liquid flowing down the outer surface of the tube and can also contribute to the extension of the contact time with the outer surface of the tube. As a result, the absorption amount of water vapor supplied from the evaporator can be further increased.

By the way, using a JIS H3300 copper tube, a heat transfer tube 10 of the structure of this embodiment having specifications such as dimensions as shown in the following [Table 1] was manufactured, and the effective length (heat transfer tube (Except for the cylindrical part provided at both ends in the axial direction of the tube to be attached to the absorber): 500 mm, set horizontally in the experimental absorber at 35 mm pitch in 5 rows, and set the heat transfer tube 10 The cooling water as the cooling medium is circulated from the lower one in 5 passes, while the LiBr aqueous solution as the absorbing liquid to which 250 ppm of octyl alcohol is added is passed through the dropping hole of the diameter: 2 mm to the tube of the uppermost heat transfer tube 10. The external heat transfer coefficient was determined for the heat transfer tube 10 having such a structure by dropping onto the outer surface. The other main conditions for such an experiment are shown in [Table 2] below.

[0040]

[Table 1]

[0041]

[Table 2]

For comparison with the heat transfer tube 10 of this embodiment, a smooth tube having a circular cross section having neither curved grooves nor fine grooves,
The same experiment was carried out for a curved groove tube in which only curved grooves having peaks and valleys were formed in the tube wall portion and no fine groove was formed, and the external heat transfer coefficient was obtained. The results are shown in FIG. 4 together with the results for the heat transfer tube 10 of the present embodiment.
Shown in.

In such an experiment, it was confirmed that in the heat transfer tube 10 having the structure of the present embodiment, the absorbing liquid flowing down the outer surface of the tube is more likely to spread in the axial direction than the smooth tube or the curved groove tube. It was In addition, from the results shown in FIG.
The heat transfer tube 10 of this example is about 40% higher than the smooth tube (Comparative Example 1) and 10% higher than the curved groove tube (Comparative Example 2).
It is acknowledged that a high outside heat transfer coefficient can be exerted.

An embodiment of the manufacturing method of the heat transfer tube 10 according to the present invention will be described below.

FIG. 5 shows a schematic structure of a drawing apparatus used for manufacturing the heat transfer tube 10. The drawing apparatus includes a support die 18, a grooved die 20, and a correction die 22, and these three types of dies 1 are provided.
8, 20, 22 are separated from each other by a predetermined distance in the axial direction,
They are arranged on a straight line. Further, the first support plug 26 is located inside the die hole of the support die 18, and the second support plug 30 is located inside the die hole of the grooved die 20. The first support plug 26 and the second support plug 30 are connected to each other by the connecting rod 3
Connected by two.

When manufacturing the heat transfer tube 10 as described above by using the drawing apparatus as described above, first, the raw pipe material 34 made of a soft copper pipe is prepared, and the raw pipe material 34 is One support plug 26 and support die 1
8, the first drawing process is performed. As a result, the raw pipe material 34 is processed into a ½H quality pipe (hereinafter, simply referred to as a pipe material) 36 as a tubular material. As the raw pipe material 34, a continuous tubular body wound in a coil shape or the like can be adopted.

By the way, this first drawing process is performed by the first belt feeder 38 arranged in front of the support die 18.
By applying a pulling force to the pipe member 36. As shown in FIG. 6, the first belt feeder 38 includes a pair of infinite belts 40, 40 positioned on both sides of the pipe member 36, and a support core 42 disposed behind each of the endless belts 40, 40. And is driven in the tube axial direction by a core moving device such as a motor (not shown). The tube member 36 is sandwiched between the pair of infinite belts 40, 40 and pulled in the axial direction. There is.

Next, the second support plug 30 and the grooved die 2 are attached to the pipe material 36 obtained by the first drawing process.
When 0, the second drawing process is performed. The second drawing process is performed by applying a drawing force to the pipe material 36 by the second belt feeder 44 arranged in front of the grooved die 20. In addition, the second belt feeder 44
The same structure as that of the first belt feeder 38 can be adopted.

At this point, the second belt feeder 44
The pressing force (clamping force) exerted on the pipe material 36 by the
0 to 55 kg / cm ² is desirable. Pushing force, pressing force is 40 kg / c
If it is less than m ² , the drawing force is weak and the drawing process becomes difficult. If the pressing force exceeds 55 kg / cm ² , the frictional force between the infinite belt and the supporting core and the load of the core moving device are increased. This is because the pipe material 36 may be deformed in addition to becoming large.

Further, as shown in FIGS. 7 and 8, the grooved die 20 is divided into three substantially equal parts in the circumferential direction, and the pipe material 3 is divided by a hydraulic cylinder (not shown) or the like.
It is possible to move back and forth in a direction perpendicular to the tube axis of No. 6.
That is, the grooved die 20 is moved toward and away from the pipe material 36 so as to come into contact with and separate from the outer peripheral surface of the pipe material 36.

Furthermore, on the inner surface of the die hole of the grooved die 20, as shown in FIG. 9, valleys 46 and peaks 48 having a curved cross-sectional shape are alternately formed in the circumferential direction. . These troughs 46 and troughs 48 are the troughs 12 and troughs 1 to be formed in the target heat transfer tube 10, respectively.
4 are formed at the same circumferential pitch.

In this embodiment, the depth of the trough portion 46 in the grooved die 20 is set to be larger than the depth d of the curved groove 15 to be formed in the heat transfer tube 10 by a predetermined amount. The second drawing process is performed stably with a small drawing force.

Further, on the outer peripheral surface of the second support plug 30 which is positioned in the die hole of the grooved die 20 and defines the inner peripheral surface shape of the pipe material 36 in the second drawing process,
The valley portion 46 formed on the inner surface of the die hole of the grooved die 20.
The peaks and valleys corresponding to the peaks 48 are alternately formed in the circumferential direction.

Furthermore, as shown in FIG. 9, on the surface of the ridges 12 formed on the grooved die 20, a large number of fine ridges 50 extending along the ridges 12 are formed.
Are formed. These concavo-convex stripes 50 are formed at the same circumferential pitch in the fine grooves 16 to be formed in the target heat transfer tube 10.

In the present embodiment, although not clearly shown in the drawing, the depth of the recess in the uneven strip 50 is
Similar to the valley portion 46, the fine groove 1 to be formed in the heat transfer tube 10.
Depth of 6: set to be larger than d by a predetermined amount,
The second drawing process is performed stably with a small drawing force.

Therefore, as shown in FIG. 7 and FIG. 9, such a grooved die 20 is brought into contact with the outer peripheral surface of the pipe material 36 and subjected to the second drawing process, whereby the second support is formed. The curved groove 15 is formed on the outer peripheral surface of the pipe member 36 in cooperation with the plug 30.
The fine groove 16 and the fine groove 16 are formed at the same time. On the other hand, as shown in FIG. 8, by separating the grooved die 20 from the outer peripheral surface of the pipe material 36, the pipe material 36 is in an unprocessed state. .

At the time of the second drawing process, by opening and closing the grooved die 20, as shown in FIG. 10, the curved groove forming portion 52 in which the curved groove 15 and the fine groove 16 are formed, The curved groove 15 and the fine groove 16
The curved groove non-formation portions 54 in which the grooves are not formed are alternately formed in the tube axis direction with appropriate lengths. Thereby, the grooved tube 56 is obtained.

After that, the grooved pipe 56 obtained by the second drawing process is subjected to the diameter reduction process for correcting the pipe diameter by the correction die 22. Although not shown, a belt feeder similar to the first belt feeder 38 is arranged in front of the correction die 22 so that a pulling force is exerted on the pipe material.

That is, in the grooved tube 56 obtained by performing the first and second drawing processes, a dimensional difference may occur in the outer diameter between the curved groove forming portion 52 and the curved groove non-forming portion 54. In addition, in general, the diameter of the curved groove unformed portion 54 is set to be slightly larger than the standard in consideration of the reduction in diameter by the second drawing process. Therefore, in order to match the diameter of the curved groove-unformed portion 54 with the attachment hole of the tube sheet or the attachment hole of the baffle plate, diameter reduction processing is performed.

The grooved tube 5 thus obtained
6 is then cut to the appropriate length. Thereby,
A desired heat transfer tube 10 is formed as shown in FIGS. 1, 2 and 10.

Therefore, in the method of manufacturing the heat transfer tube for the absorber as described above, since the curved groove 15 and the fine groove 16 are simultaneously formed by the second drawing process using one grooved die 20, As described above, without basically modifying the conventional heat transfer tube production line having only the curved groove disclosed in Japanese Patent Laid-Open No. 2-176378,
The heat transfer tube 10 including the curved groove 15 and the fine groove 16 can be easily manufactured.

Further, as a result, the heat transfer tube 10 provided with the curved grooves 15 and the fine grooves 16 has a manufacturing speed and a manufacturing cost substantially equal to those of the conventional heat transfer tube having only the curved grooves.
Can be manufactured.

Moreover, in the method of manufacturing the heat transfer tube for an absorber, the curved groove forming portion 52 and the curved groove non-forming portion 54 are formed by opening and closing the split die during the drawing process without interrupting the drawing process. It can be easily and continuously formed alternately at arbitrary intervals in the tube axis direction.

Further, in such a manufacturing method, since the curved groove forming portion 52 and the non-forming portion 54 can be continuously formed, it is possible to adopt a coiled continuous pipe as the raw pipe material. As a result, the processing efficiency can be significantly improved as compared with the case where the pipes are processed one by one.

Further, in this embodiment, the first belt feeder 38 and the second belt feeder 44 are adopted as the belt feeders that exert the pulling force on the pipe, which are necessary for the first and second pulling processes. Since the pulling-out force is divided and exerted by the two belt feeders 38 and 44, the breakage of the pipe material can be effectively prevented, and the thin-walled heat transfer tube can be manufactured. It also has advantages.

The embodiments of the present invention have been described in detail above, but these are literal examples and the present invention should not be construed as being limited to such specific examples.

For example, the heat transfer tube 10 shown in the above embodiment.
In the above, the curved groove 15 and the fine groove 16 were formed as straight grooves extending parallel to the pipe axis direction. However, the curved groove 15 and the fine groove 16 are inclined at a predetermined angle with respect to the pipe axis, and It is also possible to form it as a spiral groove extending in the direction.

Further, the heat transfer tube 1 having such a spiral groove
0 can be manufactured, for example, by forming a lead angle on the troughs 46, the peaks 48 and the uneven ridges 50 in the grooved die 20 and rotating the grooved die 20 around the axis during the drawing process. .

Further, the fine groove 16 formed at the bottom of the curved groove 15 is not limited to the arc-shaped cross-sectional shape as illustrated, but a saw-tooth-shaped cross-sectional shape or the like can be adopted. is there.

Further, in the above-described embodiment, the diameter reducing process is performed in order to finish the outer diameter of the curved groove unformed portion 54 in the heat transfer tube 10, but such a diameter reducing process is not always necessary.

Further, in the second drawing process, there may be no space in the valley portion 46 and the recessed portion of the inner surface of the die hole of the grooved die 20, and the pipe material 36 may be filled in the die hole. It is possible.

Further, in the above-described embodiment, the first belt feeder 38 which gives the pulling force in the first pulling process and the second belt feeder 44 which gives the pulling force in the second pulling process are used. , Second belt feeder 4
It is also possible to give a pulling force at the time of the first and second drawing processes only by using No. 4.

Furthermore, if the outer diameter of the second support plug 30 used in the second drawing process is tapered in the axial direction, the grooved die 20 of the second support plug 30 will be described.
By adjusting the arrangement position with respect to the axial direction, it is possible to change the wall thickness, the inner diameter, and the like of the obtained heat transfer tube 10 without replacing the grooved die 20.

Further, the heat transfer tube manufacturing method according to the present invention is characterized by the second drawing method in the above-mentioned embodiment, and the first and second drawing processes and the diameter reducing process are performed at the same time. Sequential application is not essential.

Further, in the above-described embodiment, the second support plug 30 which defines the inner peripheral surface of the pipe material 36 is used in the second drawing process, but the curved groove 15 and the fine groove 16 to be formed are formed. Depending on the size and the material of the pipe material 36, the second support plug 30 may not be needed.

Although not listed one by one, the present invention
Based on the knowledge of those skilled in the art, it can be implemented in various modified, modified, and improved modes, and
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[Brief description of drawings]

1 is a cross-sectional view showing an embodiment of a heat transfer tube for an absorber having a structure according to the present invention.

FIG. 2 is a side view of the heat transfer tube shown in FIG.

3 is an enlarged cross-sectional view of a main part of the heat transfer tube shown in FIG.

FIG. 4 is a graph showing a result of measuring a heat transmission rate in the heat transfer tube having the structure of the present embodiment as shown in FIG. 1, together with a comparative example.

5 is a schematic configuration diagram showing an example of a drawing apparatus used for manufacturing the absorber heat transfer tube shown in FIG. 1 according to the method of the present invention.

6 is a cross-sectional explanatory view showing a belt feeder used in the drawing processing apparatus shown in FIG.

7 is a cross-sectional explanatory view for explaining the structure and operation of the grooved die used in the drawing apparatus shown in FIG.

8 is a cross-sectional explanatory diagram for explaining another operating state of the grooved die shown in FIG. 7. FIG.

9 is an enlarged cross-sectional view of a main part showing a processing state of a pipe material by the grooved die shown in FIG.

10 is a side view showing a heat transfer tube manufactured by the drawing apparatus shown in FIG.

[Explanation of symbols]

 10 Heat Transfer Tube 12 Mountain Part 14 Valley Part 15 Curved Groove 16 Fine Groove 20 Groove Die 36 Tubing Material 46 Tubular Part 48 Valley Part 50 Crest 50 Uneven Line 52 Curved Groove Formation Part 54 No Curved Groove Formation Part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Yoshii, 2-18 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Masahiro Furukawa 2-chome, Keihan Hon-dori, Moriguchi, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A heat transfer tube for an absorber, wherein an absorbing liquid is brought into contact with an outer peripheral surface of a pipe while a cooling medium is allowed to flow in the pipe, wherein peaks and troughs having a curved cross-section are alternately provided in a pipe circumferential direction. hand,
An absorption characterized by forming a plurality of curved grooves extending in the pipe longitudinal direction, and forming a large number of fine grooves extending in the pipe longitudinal direction along the valleys on the outer peripheral surface of the pipe at the valleys of the curved grooves. Heat transfer tube. 2. A plurality of curved grooves extending in the pipe longitudinal direction are formed by alternately providing peaks and valleys having a curved cross-sectional shape in the pipe circumferential direction, and at the outer peripheral surface of the valley of the curved grooves, When manufacturing a heat transfer tube for an absorber in which a large number of fine grooves extending in the tube longitudinal direction are formed along the valley, it is divided in the circumferential direction and can be opened and closed by advancing and retracting in the direction perpendicular to the central axis. At the same time, valleys and ridges having a curved cross-sectional shape are alternately formed on the inner surface of the die hole in the circumferential direction, and a large number of fine uneven lines extending along the ridges are formed on the surface of the ridges. Using a split die, a predetermined tubular material is subjected to a drawing process, and by opening and closing the split die at the time of the drawing process, the curved groove and the fine groove are formed on the outer peripheral surface of the pipe, and a curved groove forming portion thereof. Unformed curved groove without curved groove and fine groove Preparative method of absorbing dexterity heat transfer tube and forming alternately in the tube axis direction.