JPH02165875A - Heat exchanger tube and its manufacture - Google Patents

Abstract

PURPOSE:To improve both characteristics of evaporation and condensation of the heat exchanger tube by forming many notches to cross mutually on fin parts and groove bottoms of inside grooves of the heat exchanger tube form vacancies. CONSTITUTION:The plural fine inside grooves 11 are formed on the inside of the heat exchanger tube 1 and these inside grooves 11 are provided continuously on the tube inside and formed parallel or spirally with respect to the tube axis. Many notches 12 are formed on the inside of the heat exchanger tube 1 and the notches 12 are formed in the mutually different directions and formed parallel or so as to cross mutually on the fin parts 11a and the groove bottoms 11b of the inside grooves 11. Many vacancies are formed on the inside of the heat exchanger tube 1 by these notches 12. By this method, the heat exchanger tube excellent in both evaporating performance and condensing performance and moreover, having little variance on those is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat exchanger tube used in a heat exchanger for refrigerators, air conditioners, etc., and a method for manufacturing the same.

[Conventional technology]

Generally, heat transfer tubes used in heat exchangers for refrigerators and air conditioners exchange heat by flowing a refrigerant liquid such as Freon inside the tube. Grooved heat exchanger tubes are increasingly being used. These internally grooved heat transfer tubes have minute grooves with triangular or trapezoidal cross sections formed inside the tube, parallel to the tube axis or spirally, and have a larger heat transfer area than smooth tubes. It has the advantage of increasing the amount of water and stirring the refrigerant liquid, and the heat transfer performance is greatly improved.

In recent years, there has been a strong demand for higher performance, smaller size and lighter weight, especially for heat exchangers for air conditioners, and with the spread of heat pump air conditioners, there has been an even stronger demand for higher performance for heat exchanger tubes. ing.

[Problem to be solved by the invention]

However, with conventional internally grooved heat exchanger tubes, the number of grooves, lead angle,
Although many improvements have been made to groove depth, groove shape, etc.
There were naturally limits to performance improvement.

On the other hand, in order to meet these demands, a heat exchanger tube in which a porous layer is formed by sintering metal powder on the inner surface of the tube has been developed in place of the conventional heat exchanger tube with internal grooves.

In this heat transfer tube, when evaporating inside the tube, the formed porous layer promotes nucleate boiling, and the heat transfer performance is greatly improved. However, when condensing inside the tube, the condensed refrigerant liquid stays in the porous layer. In some cases, a liquid film was formed on the inner surface of the tube without stirring, and heat transfer performance was not improved.

In addition, this heat transfer tube requires many manufacturing steps, and it is difficult to form a porous layer uniformly when processing long objects, so there are drawbacks such as variations in heat transfer performance. .

An object of the present invention is to provide a heat exchanger tube that has good evaporation performance and condensation performance and less variation in them.

Still another object is to provide a method for manufacturing a heat exchanger tube that can easily process such a heat exchanger tube into a long length.

[Means for Solving the Problems] In order to solve the above problems, the heat exchanger tube according to the present invention has a large number of fine inner grooves formed continuously in a spiral shape or parallel to the tube axis on the inner surface of the tube. The heat exchanger tube has a structure in which a large number of cuts in mutually different directions are formed in the fin portion and the groove bottom of the inner groove so as to be parallel or intersect with each other.

Further, the method for manufacturing a heat exchanger tube according to the present invention includes forming a large number of mutually parallel grooves in parallel or spirally with respect to the tube axis on the inner surface of the tube, and forming other mutually parallel grooves parallel to or intersecting with these grooves. By forming a large number of grooves one or more times,
By forming a large number of protrusions or recesses on the inner surface of the tube, and while crushing these protrusions or recesses, forming an inner groove on the inner surface of the tube parallel to the tube axis or continuously in a spiral shape, the inner surface of the tube can be improved. The structure is such that a large number of parallel or intersecting cuts in different directions are formed in the fin portion of the groove or the bottom of the groove.

[Effect]

Since the heat exchanger tube according to the present invention has voids formed by a large number of cuts, the nucleate boiling during evaporation of the refrigerant liquid can be greatly improved compared to the conventional heat exchanger tube with internal grooves. This results in approximately the same evaporation performance as that of a heat exchanger tube with a porous layer formed thereon.

In addition, when the inside of the pipe is compressed, basically an inner groove is formed, so that the compressed refrigerant liquid is appropriately stirred and does not form a liquid film. This improves condensation performance compared to conventional internally grooved heat exchanger tubes.

Furthermore, the method for manufacturing a heat exchanger tube according to the present invention basically requires only repeating the grooving process multiple times during the manufacture of conventional internally grooved heat exchanger tubes, and uses substantially the same equipment to process long objects. can now be manufactured without any variation.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings and the like.

FIG. 1 is a diagram showing an embodiment of a heat exchanger tube according to the present invention, in which FIG. 1A is an expanded view of the inner surface of the heat exchanger tube, and FIG. 1B is an enlarged view of a part of the heat exchanger tube. FIG.

The heat exchanger tube 1 has a plurality of fine inner grooves 11 formed on its inner surface. This inner surface groove 11 is provided continuously on the inner surface of the tube, and is formed parallel to the tube axis or in a spiral shape.

A large number of cuts 12 are formed on the inner surface of the heat exchanger tube l. The cuts 12 are formed in mutually different directions, and are formed in the fin part 1a of the inner groove 11 and the groove bottom 11b so as to be parallel to each other or to cross each other. This cut 12 forms a large number of holes on the inner surface of the heat exchanger tube l.

FIG. 2 is a diagram for explaining an embodiment of the method for manufacturing a heat exchanger tube according to the present invention.

The heat exchanger tube 1 is manufactured using a manufacturing device 12 using a raw tube 10 such as a steel tube.
It can be manufactured by

The manufacturing apparatus 2 includes a diameter-reducing die 21 arranged outside the raw pipe 10 to reduce the diameter of the raw pipe 10, a floating plug 22 provided inside the raw pipe 10 facing the diameter-reducing die 21, and a floating The plug 22 has first to third grooved plugs 24 to 26 held at fixed positions inside the raw pipe 10 by a connecting rod 23, and first to third grooved plugs 24 to 26 outside the raw pipe 10. The first to third rolling rollers 27 to 29 are arranged at opposing positions and perform a diameter reduction process on the raw pipe 10 while rotating.
It is composed of.

First, the first grooved plug 24, the first rolling roller 27, the second grooved plug 25, and the second rolling roller 28 form a large number of fine approximately quadrangular pyramidal or saw blade-shaped projections in the raw pipe 10. Next, the third grooved plug 26 and the third rolling roller 29
Thus, the inner groove 11 is formed.

Here, when forming the inner groove 11 using the third grooved plug 26, the inner groove 11 is formed by crushing the substantially square pyramid or saw blade-shaped protrusions formed in the previous step. Mainly to form.

Therefore, the fin portion 11 formed by the inner groove 11
Parallel or intersecting notches 12 are formed in the shape of substantially square pyramidal or saw blade-shaped protrusions crushed in a and the groove bottom llb, and a large number of holes are formed therein.

In this embodiment, the first grooved plug 24 has 90 grooves.
, a plug with a lead angle of 28 degrees (right-handed twist) and a groove depth of 0.15 mm is used, and the second grooved plug 25 has a number of grooves of 80, a lead angle of 20 degrees (left-handed twist), and a groove depth of O, 10 mm. The third grooved plug 26 had a groove count of 60, a lead angle of 18 degrees (right-handed twist), and a groove depth of 0.20 mm.As a result of grooving using a steel pipe as the base pipe 10, the number of grooves was 60, lead angle 18 degrees (right-handed twist), groove depth 0.20 m
An inner groove 11 of m was obtained. Thereafter, the heat exchanger tube 1 having an outer diameter of 9.53 mm was obtained by passing through a dry die (not shown). As shown in FIG. 1, a large number of cuts 12 were formed on the inner surface of the obtained heat exchanger tube 1 so as to intersect with the fin portion 11a and the groove bottom portion 11b of the inner groove 11.

FIG. 3 and FIG. 4 are diagrams respectively showing the evaporation performance and condensation performance within the tube of an example of the heat exchanger tube according to the present invention.

The heat transfer of the produced heat exchanger tube 1 was measured using a double tube heat exchanger. The characteristics (A) of the internally grooved heat exchanger tube according to the present invention are as follows:
As shown in Figures 3 and 4, compared to the characteristics (B) of the conventional internally grooved heat exchanger tube, the tube evaporation performance is approximately 100%, and the tube li! The compression performance improved by about 70%.

The conventional internally grooved heat exchanger tube used in this heat transfer measurement had an outer diameter of φ9.53 mm and a groove count of 60. Lead angle 18 degrees, groove depth 0
．． A 20 mm one was used.

FIG. 5 is a diagram for explaining another embodiment of the method for manufacturing a heat exchanger tube according to the present invention.

The manufacturing apparatus shown in FIG. 2 shows an example of rolling the raw tube 10, but in this embodiment, the heat exchanger tube 3 is manufactured by the manufacturing apparatus 4 using the strip plate 30.

The band plate 30 has a first grooved roller 41 having a spiral groove.
A third grooved roller 43 forms a large number of fine substantially quadrangular pyramidal or saw blade-shaped protrusions on one side of the strip plate 30 by the flat roller 44, the second grooved roller 42, and the flat roller 45. and the flat roller 46, the inner groove 31
form.

At this time, when the third grooved roller 43 forms the inner groove 31, the inner groove 31 is formed by crushing the substantially square pyramid or saw blade-shaped protrusions formed in the previous process. .

Next, it is formed into a tubular shape by a group of forming rollers 47a to 47h, and then high-frequency induction welding is performed using an induction coil for four days, and then the squeeze roll 49a is formed.

49b, the heat exchanger tube 3 was manufactured. The obtained heat exchanger tube 3 has a large number of cuts 3 in the inner groove 31, as shown in FIG.
2 was formed.

Various modifications can be made without being limited to the embodiments described above.

In the embodiment described here, the substantially square pyramid or saw blade-shaped protrusions are formed by grooving twice, but it is also possible to form inner grooves in the second grooving. good.

Furthermore, the shape of the inside of the pipe after the second groove machining may be any shape, and when grooving mainly forms internal grooves, the protrusions or grooves formed after the second groove machining are pressed. All you have to do is destroy it, and
The shape of each groove (losing streak, lead angle) from the first and second groove machining.

By appropriately selecting the groove depth, etc., parallel or intersecting cuts may be made on the inner surface of the tube as shown in FIG. 1, and these may form a large number of holes.

In addition, in this embodiment, an example was explained in which the inner groove was formed by grooving three times, but the number of grooving is not limited to three times.
It may be four, five or more times, and the internal groove may be machined to form multiple intersecting cuts during the final groove machining.

Note that after the strip plate is pipe-processed using the roller groups 47a to 47h shown in FIG. 5, the groove may be processed using the manufacturing apparatus 2 shown in FIG. 2.

〔Effect of the invention〕

As explained in detail above, according to the present invention, a large number of intersecting cuts are made in the fin portion and the groove bottom of the inner groove of the heat exchanger tube to form holes, thereby improving both the evaporation and am characteristics. I was able to improve it significantly. Therefore, it can be suitably used as a heat pump type heat exchanger tube.

In addition, since the manufacturing method is almost the same as that of conventional internally grooved heat exchanger tubes, long products can be easily processed, etc.
It is extremely useful industrially.

[Brief explanation of the drawing]

FIG. F is a diagram showing an embodiment of the heat exchanger tube according to the present invention, FIG. 1A is an expanded view of the inner surface of the heat exchanger tube, and FIG. 1B is an enlarged view of a part of the heat exchanger tube. FIG. FIG. 2 is a diagram for explaining an embodiment of the method for manufacturing a heat exchanger tube according to the present invention. FIG. 3 and FIG. 4 are diagrams respectively showing the evaporation performance in the tube and the condensation performance in the tube of an example of the heat exchanger tube according to the present invention. FIG. 5 is a diagram for explaining another embodiment of the method for manufacturing a heat exchanger tube according to the present invention. 1... Heat exchanger tube 11... Inner groove 11a... Fin portion 11b... Groove bottom 12
... Cutting depth 2 ... Manufacturing equipment 21 ... Diameter reducing die 22 ... Floating plug 23 ... Connecting rods 24 to 26 ... First to third grooved plugs 27 to 29 ...
・First to third transfer rollers 3...Heat transfer tube 31...Inner groove 32...Notch 4...
・Manufacturing devices 41 to 43...first to third grooved rollers 44 to 46...
・Flat rollers 47a to 47h... Forming roller group 48... Induction coil 1A Fig. 11t) Fig. B

Claims (2)

[Claims] (1) In a heat exchanger tube having a large number of fine inner grooves formed parallel to the tube axis on the inner surface of the tube or continuously in a spiral shape, the grooves are parallel to or intersect with the fins or groove bottoms of the inner grooves. A heat exchanger tube characterized in that a large number of cuts are formed in mutually different directions. (2) A large number of mutually parallel grooves are formed parallel to or spirally with respect to the tube axis on the inner surface of the tube, and many other mutually parallel grooves that are parallel to or intersect with these grooves are formed one or more times. By forming a large number of protrusions or recesses on the inner surface of the tube, and while crushing those protrusions or recesses, forming an inner groove on the inner surface of the tube parallel to the tube axis or continuously in a spiral shape. A method for manufacturing a heat exchanger tube, comprising forming a large number of parallel or intersecting cuts in mutually different directions in the fin portions and groove bottoms of the internal grooves.