JPH02137609A - Heat exchanger tube for tube condensation and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a heat exchanger tube for inner tube condensation with excellent heat transfer coefficient of condensation heat by forming spiral grooves or grooves met at right angles to the tube axis inside a tube and forming axially grooves which divide into section the above grooves by drawing a plug with projections. CONSTITUTION:Spiral grooves 1 are formed inside the heat exchanger tube 10 using a groove plug and rolling ball. After or in that process, the drawing is performed by the plug 31 with plural projections 32 on its surface. By these projections 32, parallel grooves 2 are formed continuously and axially inside the tube. The above spiral grooves are divided into section by the grooves 2. When a refrigerant is condensed inside the tube using the heat exchanger tube 10 obtained by these processes, the refrigerant vapor is generated turbulant flow by the spiral grooves 1 and the heat transfer efficiency is improved and a liquid film is prevented to form inside the tube by suppressing to comb up the liquefied refrigerant by the above parallel grooves 2. Therefore, the heat exchanger tube 10 for inner tube condensation is increased the heat transfer coefficient of condensation heat particularly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a heat exchanger tube for a heat exchanger, particularly a heat exchanger tube for condensing a refrigerant in the tube to exchange heat, and a method for manufacturing the same.

[Prior art] Heat exchangers in refrigerators, air conditioners, heat pumps, etc. use heat exchanger tubes for condensation within the tubes, which pass refrigerant through the tubes and condense the refrigerant within the tubes to perform the necessary heat exchange. has been done.

Initially, the inner surface of such heat transfer tubes was smooth, but as thermodynamic research progressed, it became clear that the heat transfer coefficient would be better if the inner surface of the tube was not smooth but had a certain unevenness. Recently, as shown in Fig. 3, heat exchanger tube 10
Types in which continuous spiral grooves 1- (or grooves perpendicular to the tube axis, hereinafter the same) are formed on the inner surface of the tube have become mainstream.

As an effect of forming the spiral arm 1- in this way,
For one thing, this increases the surface area of the inner surface of the tube, increasing the heat transfer area.

However, not only that, the existence of spiral irregularities inside the pipes causes the circulating refrigerant to become agitated and turbulent, which improves the heat transfer coefficient. In this case, the chilled liquid flowing inside the tube is scraped up along the drain 1-11-, and the entire inner surface of the tube is wetted with the refrigerant liquid, which can be expected to improve the heat transfer coefficient.

[Problems to be Solved by the Invention] Although the heat exchanger tube with the inner spiral surface has the excellent heat transfer characteristics described above, it is not advantageous in all respects. In particular, when refrigerant is used after being condensed within the pipes, the following problems arise.

In other words, the refrigerant liquid condensed inside the pipe accumulates at the bottom of the pipe due to gravity and flows down the pipe.
．． Due to the presence of 1-21-, the liquefied refrigerant does not flow smoothly, and the above-mentioned scraping phenomenon due to the spiral quenching 1-21- occurs, resulting in the entire inner surface of the tube becoming wet.

When the inner surface of the tube is wetted with liquid in this way, the inner wall surface of the tube does not come into direct contact with the gaseous refrigerant vapor, so there is a risk that the heat transfer coefficient will be significantly reduced. For this reason,
In the case of heat transfer tubes for condensation, it is more important to enable direct contact between the inner wall surface of the tube and the refrigerant vapor over a larger surface area.

The object of the present invention is to provide a novel condensing heat transfer tube and a condensing heat transfer tube capable of greatly suppressing the occurrence of the refrigerant liquid scraping phenomenon and significantly increasing the condensing heat transfer coefficient, in view of the above-mentioned circumstances. This paper attempts to provide a manufacturing method for the same.

[Means for Solving the Problems] A first aspect of the present invention is that the groove of a heat exchanger tube having a spiral break on the inner surface of the tube is divided by another groove, and a second aspect of the present invention is that A pipe having a spiral groove is drawn using a plug having a protrusion on the surface thereof, a groove continuously extending in the axial direction is formed on the inner surface of the tube by the protrusion of the plug, and the spiral groove is divided by the groove. It is in the manufacturing method.

[Function] The spiral grooves on the inner surface of the tube create turbulent flow in the refrigerant vapor, which can improve heat transfer efficiency, while the spiral grooves are separated by grooves extending in the axial direction, which prevents the liquefied refrigerant from being stirred up. , the formation of an unnecessary liquid film on the inner surface of the tube is prevented.

Further, by using a plug with a surface protrusion and pulling it out, it is possible to easily form a groove that divides the spiral groove.

[Example 1 The present invention will be described below with reference to the drawings.

FIG. 1 is a half-cut sectional view showing the inner surface of an embodiment of the heat exchanger tube 10 according to the present invention.

1.1 is a spiral formed on the inner surface of the tube 10, and 2
．． Reference numeral 2 denotes a parallel groove parallel to the tube axis direction that divides the spiral banks 1, 1 as shown in the figure.

Unlike the conventional example shown in FIG. 3, in the present invention, the spiral eraser 1
, 1 are separated by the parallel grooves 2, 2, even if the condensed refrigerant liquid is scraped up, the scraped up will not be scraped up beyond the parallel grooves 2, 2. It can be stopped within a limited range.

FIG. 4 is an explanatory longitudinal cross-sectional view showing how the heat exchanger tube 10 according to the present invention configured as described above is being manufactured.

10A is a material tube, which is first pulled out between the tie 20 and the floating plug 21 and reduced in diameter.

A plug 23 is connected to the floating plug 21 via a rod 22, and spiral plugs 1, 1 are formed on the inner surface by rolled balls 24, 24 rotating at high speed around the groove plug 23.

A protrusion plug 26 having protrusions 26a, 26a on the outer periphery is further connected to the groove plug 23 via a rod 25, and the tube in which the helical shafts 1, 1 are formed is connected to the protrusion plug 26 and the die 27. It is drawn between

In this drawing process, the protrusions 26a, 26a further form parallel grooves 2, 2 on the inner surface of the tube having the helical groove 1.1, thereby dividing the helical fit, 1.

By doing the above, the heat exchanger tube 10 according to the present invention shown in FIG. 1 can be manufactured continuously in one process.

FIG. 5 is an explanatory longitudinal cross-sectional view showing how the heat exchanger tube 1o is manufactured by yet another method.

In this method, the spiral arms 1, 1 are formed in separate processes, and the spiral grooved pipes, which are not processed separately, are connected to the tie 3.
0 and a floating plug 31 by drawing.

A projection 32° 32 is provided on the surface of the floating plug 31, and the projection 3 is removed when the floating plug 31 is pultruded.
2.32 forms continuous parallel grooves 2.2 on the inner surface of the tube, thereby dividing the helical strands 1.1 to produce the heat exchanger tube 10 according to the present invention.

If the parallel grooves 2, 2 are formed using the floating plugs 21 or 31 as described above, an additional feature can be exhibited in that the depth of the parallel grooves can be averaged and stabilized.

That is, the protrusion 26a forming the parallel grooves 2,2.

26a or 32. If you try to go deep into the clearing 1, 1 from 32, the plug will be pushed back by the deformation resistance and move to the side where the amount of deformation is shallow, and the plug will be automatically adjusted so that the same depth of clearing is achieved throughout. This is because a so-called self-centering effect can be expected.

In the illustrated example, four protrusions of the plug are provided at 90° intervals in the circumferential direction, but it goes without saying that this arrangement is more convenient when viewed from above the self-centering ring. However, it is not always necessary to be limited to such an arrangement.

FIG. 2 shows an example in which the protrusions 32 and 32 of the plug 31 in FIG. 5 (the same applies to the plug 26 in FIG. 4) are provided centrally below the heat exchanger tube 10 to be manufactured. .

In this way, the parallel groove 2 that divides the spiral arm 1.1
, 2 are formed in a concentrated manner below the tube 10, the condensed refrigerant liquid will flow smoothly through this clear liquid in the direction of the tube axis with little resistance, and the above-mentioned scraping phenomenon will be reduced accordingly. .

Although the above description has been made assuming that the grooves dividing the spiral groove 1.1 are formed parallel to the tube axis, they do not necessarily have to be parallel. For example, there is no problem in dividing the helical groove with another helical groove by rotating a plug with a protrusion in the tube in the opposite direction to the direction in which the helical strand is formed.

[Effects of the Invention] As described above, according to the heat exchanger tube according to the present invention, the condensation heat transfer coefficient of the refrigerant can be significantly improved, and the size of the heat exchanger and, in turn, the size of the refrigerant device can be reduced. It has great industrial value, as it can reduce equipment costs and running costs.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a half-cut sectional view showing an embodiment of the heat exchanger tube according to the present invention, Fig. 2 is an explanatory drawing showing an example of the arrangement of the protrusions of the plug, and Fig. 3 is a conventional FIGS. 4 and 5 are half-cut cross-sectional views showing a heat exchanger tube, and are joint cross-sectional explanatory views showing a 2 m method for manufacturing a heat exchanger tube according to the present invention. 1.1-: spiral groove, 2: parallel groove, to, io: heat exchanger tube, 26.31: plug with protrusion, 26a, 32: protrusion.

Claims (2)

[Claims] (1) A heat exchanger tube for condensing inside a tube, which is formed by dividing the groove of a heat exchanger tube having a spiral groove or a groove perpendicular to the tube axis on the inner surface of the tube with a groove formed separately from the groove. (2) forming the groove of a heat transfer tube having a spiral groove or a groove perpendicular to the tube axis on the inner surface of the tube in advance or in the same process, and drawing the tube using a plug having a protrusion on the surface; A method of manufacturing a heat exchanger tube for condensing inside a tube, in which a groove continuously extending in the axial direction is formed on the inner surface of the tube by the protrusion of the plug, and the groove divides the spiral groove or orthogonal groove.