JP2012083006A - Heat transfer tube, and method and device for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat transfer tube capable of improving heat transfer rate inside the tube while suppressing increase of pressure loss, and to provide a method and device for manufacturing the same.SOLUTION: Helical fins 2 are formed on a tube inner surface 10, and main grooves 3 are formed between the fins 2, 2. A sub groove constitution part 6 is composed of a sub groove edge part 4 composing a peripheral edge part of a sub groove 7 formed at the fin 2 and a main groove side projection 5 projecting to the main groove 3 side on the upstream side of a tube axial direction D1 at an end part of at least an upstream side D2u in a fin forming direction in the sub groove edge part 4. The sub groove constitution part 6 is composed of a base end side sub groove composition part 6A on a base end side in a projecting direction from the tube inner surface 10 and an edge side sub groove composition part 6B on an edge side in the projecting direction. In a sub groove angle α composed by the sub groove constitution part 6, a sub groove angle α formed by the base end side sub groove constitution parts 6A defines a base end side sub groove angle α, and a sub groove angle α formed by the edge side sub groove constitution parts 6B defines an edge side sub groove angle α. The sub groove constitution parts 6 are formed in a shape in which the edge side sub groove angle αbecomes larger than the base end side sub groove angle α.

Description

  The present invention relates to a heat transfer tube used in a heat exchanger such as a refrigerator or an air conditioner, a manufacturing method thereof, and a manufacturing apparatus thereof.

  In general, heat transfer tubes used in air conditioners, refrigerators, etc., perform heat exchange with the fluid flowing outside the tubes by evaporating or condensing the refrigerant in the tubes, which improves the efficiency and energy saving of the heat exchanger. From the viewpoint, an inner grooved tube is often used.

  In such an internally grooved tube, a linear or spiral fin is formed with respect to the tube axis, and a main groove is formed between adjacent fins. By providing these grooves on the inner surface of the tube, the heat transfer area is increased as compared with the smooth tube, and the heat transfer performance can be improved by the stirring action of stirring the refrigerant.

In recent years, there has been a strong demand for higher performance and smaller size and weight especially for heat exchangers for air conditioners, and with the revision of the Energy Saving Law, there has been a further demand for higher performance of heat transfer tubes.
However, in the conventional internally grooved tube, although the number of grooves, the lead angle, the groove shape, and the like have been improved, the performance required as described above is insufficient.

  Therefore, as a heat transfer tube that replaces these conventional internally grooved tubes, for example, Patent Document 1 discloses that the fins are divided by the auxiliary grooves in order to promote the stirring action of the refrigerant among the internal grooved tubes. A heat transfer tube with a so-called cross groove that intersects with the groove is disclosed.

In the heat transfer tube with a cross groove, the fin (12) is divided by a sub-groove, and a plurality of fin constituent portions (12A) protruding spirally from the inner surface of the tube are formed on the inner surface of the tube. It is the structure provided with the protrusion piece (16a) which protrudes in the side of the main groove between the said fins (12) which adjoins at the pipe-axis direction upstream at least in the spiral direction downstream of the said fin structure part (12A). .
In addition, since the protrusion piece (16a) protrudes to the main groove side, it is also called a main groove side protrusion piece.

  According to Patent Document 1, such a heat transfer tube is provided with a protruding piece (16a), so that a part of the refrigerant flowing between the fins (12) collides with the protruding piece (16a), and the tube It is disclosed that three-dimensional unsteady flow, that is, turbulent flow, can be effectively generated and the heat transfer coefficient in the tube can be improved because it is lifted inward in the radial direction.

However, in the configuration of the heat transfer tube in Patent Document 1, when further improving the heat transfer coefficient in the tube, a larger number of sub-grooves are formed in the fin (12), whereby the fin (12) It is conceivable to form more protruding pieces (16a).
This is because it can be considered that the more the number of protruding pieces (16a) formed on the fin (12) increases, the more the turbulent flow of the refrigerant can be expected.

However, when the number of the projecting pieces (16a) formed on the fin (12) on the inner surface of the pipe is simply increased, there arises a problem that the pressure loss increases and the heat transfer coefficient in the pipe decreases.
For this reason, the structure of the conventional heat transfer tube with a cross groove like the heat transfer tube disclosed in Patent Document 1 has a limit in improving the heat transfer coefficient in the tube.

  Further, in order to increase the number of protruding pieces (16a) formed on the fin (12) on the inner surface of the pipe, it is necessary to form a large number of sub-grooves on the fin (12). When installing in the aluminum fin of the heat exchanger, it is not possible to secure the strength of the fin that can withstand the mechanical expansion by inserting the expansion plug into the heat transfer tube, and it is difficult to expand the heat transfer tube mechanically. In order to improve the heat transfer coefficient in the tube, the number of protruding pieces (16a) may be increased simply because the formation of the narrow pitch makes it difficult to manufacture the heat transfer tube due to the performance limitation of the processing apparatus. could not.

JP 2009-162389 A

  Then, this invention aims at provision of the heat exchanger tube which can aim at the improvement of the heat transfer coefficient in a pipe | tube, suppressing the increase in pressure loss, its manufacturing method, and its manufacturing apparatus.

In the present invention, a spiral fin having a predetermined angle with respect to the tube axis direction is formed on the inner surface of the tube, a main groove is formed between the adjacent fins, and a concave sub-groove formed in the fin. A sub-groove edge portion constituting the peripheral portion of the main groove side, and a main groove-side protruding piece projecting at the upstream end portion in the fin forming direction at the sub-groove edge portion toward the main groove side on the upstream side in the tube axis direction A heat transfer tube comprising a sub-groove constituting portion, wherein the base end side in the projecting direction from the inner surface of the sub-groove constituent portion is defined as a base-side sub-groove constituent portion, and the tip end side in the projecting direction is The sub-groove angle formed by the base-side sub-groove constituent portion among the sub-groove angles formed by the sub-groove constituent portions opposed to both sides in the fin forming direction in the sub-groove is defined as the front-end side sub-groove constituent portion. with the minor groove angle alpha _1, the sub-groove angle between the distal-side sub grooves component, the distal end side auxiliary groove angle _2, and the sub-groove arrangement portion, and forming than the proximal-side sub groove angle alpha ₁ in the front end side auxiliary groove angle alpha ₂ increases shape.

  With this configuration, it is possible to provide a heat transfer tube capable of improving the heat transfer coefficient in the tube while suppressing an increase in pressure loss.

Specifically, as described above, the sub-groove arrangement portion having a tube inner surface, by than the proximal-side sub groove angle alpha ₁ is formed in the distal-side sub groove angle alpha ₂ increases shape, wherein Compared to a conventional heat transfer tube in which a sub-groove component having a shape in which the base-side sub-groove angle α ₁ and the distal-side sub-groove angle α ₂ are substantially the same size is formed on the inner surface of the tube, It is possible to actively promote turbulent flow of refrigerant including
Therefore, it is possible to improve the heat transfer coefficient in the tube while suppressing an increase in pressure loss.

Here, the sub-groove constituting portion is formed in a shape in which the distal-end-side sub-groove angle α ₂ is larger than the proximal-end side sub-groove angle α _1. As it progresses to the tip side secondary groove constituting part, even if it is a shape that gradually warps outward on the opposite side with respect to the secondary groove, it bends stepwise and bends outward on the opposite side with respect to the secondary groove. A shape may be sufficient and the shape is not limited.

Further, the distal-side sub groove angle alpha ₂ is larger shape than the proximal-side sub groove angle alpha ₁ is tangent angle of the entire opposing portion facing separating the minor groove in the proximal-side sub grooves constituting unit However, the shape is not limited to a shape that is larger than the tangential angle of the entire facing portion facing the sub-groove in the tip side sub-groove constituting portion.

Specifically, the the proximal-side sub groove angle alpha ₁ wherein the distal end side auxiliary groove angle alpha ₂ is larger shape than, for example, the counter portion facing at a sub-groove in the proximal-side sub grooves constituting unit A shape in which at least a part of the tangent angle is larger than at least a part of the tangent angle at the opposing part facing the sub-groove in the tip side sub-groove constituting part is also included.

An embodiment of the present invention, the base end side auxiliary groove angle alpha ₁ is in the range of 90 ° from 10 °, the distal end side auxiliary groove angle alpha ₂ may be in the range of 170 ° from 30 °.

As described above, the base-side sub-groove angle α is also included in the configuration in which the sub-groove component is formed in a shape in which the distal-side sub-groove angle α ₂ is larger than the base-end side sub-groove angle α _{1. by 1} and said distal end side auxiliary groove angle alpha ₂ is formed to have a relationship described above, while suppressing an increase in pressure loss, it is possible to further improve the tube heat transfer coefficient.

Furthermore, each of the base end side sub-groove constituent portion and the tip end side sub-groove constituent portion can be endured without being damaged even if pressure due to the collision of the refrigerant continues to be applied. A sub-groove having a suitable shape in which the angle balance between the base-side sub-groove angle α ₁ and the tip-side sub-groove angle α ₂ is balanced from the strength surface and the processed surface, such as the groove constituting portion is not broken. It can be a component.

  As an aspect of the present invention, the main groove-side protruding piece can be formed at a protruding angle within a range of 5 ° to 90 ° with respect to the fin from the sub-groove edge in a plan view with respect to the fin. .

Since the main groove side protruding piece is formed with the above-described configuration, the flow of the refrigerant flowing through the main groove is not excessively hindered by the main groove side protruding piece, and a part of the refrigerant is protruded from the main groove side. It can be made to collide with the piece and be guided from the main groove side protruding piece to the sub groove side. Therefore, the heat transfer tube can improve the heat transfer coefficient by a larger refrigerant stirring action.
Furthermore, since the refrigerant flow rate in the tube axis direction increases in the heat transfer tube, an increase in pressure loss can be suppressed.

  Moreover, as an aspect of the present invention, the ratio of the main groove side protruding piece to the interval between the main grooves can be set in a range of 0.1 to 0.9.

Thus, by forming the main groove side protruding piece with a protruding length of a ratio of 0.1 or more with respect to the interval between the fins, a part of the refrigerant flowing through the main groove is part of the main groove. It is possible to promote the turbulent flow including the inner side in the pipe radial direction by colliding with the side protruding piece, and to further improve the heat transfer coefficient by the larger refrigerant stirring action.
Furthermore, the flow of the refrigerant from the main groove side protruding piece to the sub groove side can be guided, and the flow rate of the refrigerant in the tube axis direction increases, so that an increase in pressure loss can be prevented.

  The main groove side protruding piece is formed with a protruding length having a ratio of 0.9 or less with respect to the interval between the fins, without excessively hindering the flow of the refrigerant flowing through the main groove, The effect of pressure loss due to the formation of the main groove side protruding piece can be mitigated.

  As an aspect of the present invention, the sub-grooves can be formed with 4 to 60 strips per pipe circumference.

  In this way, by forming the sub-grooves with the number of strips of 4 or more per pipe circumference, the interval in the fin forming direction between adjacent sub-grooves formed in the fins does not become too large, and sufficient refrigerant stirring action is obtained. be able to.

  On the other hand, by forming the sub-grooves with the number of strips of 60 or less per tube circumference, a fin strength that can withstand the mechanical tube expansion by inserting the tube expansion plug into the heat transfer tube when assembling into the aluminum fin of the heat exchanger is ensured. can do.

Further, according to the present invention, the inner surface of the tube is crushed by a main groove forming plug having an inner surface fin forming groove on the outer periphery while the element tube is pulled out from the upstream side to the downstream side, so By forming fins on the inner surface of the pipe, a main groove forming step for forming a main groove between the adjacent fins, and a secondary groove forming blade that intersects the fin at a predetermined crossing angle on the outer periphery are provided. By forming the sub-groove in the fin with the groove-forming plug, the sub-groove edge portion at the peripheral edge portion of the sub-groove, and at least the upstream end portion of the sub-groove edge portion in the fin forming direction And a sub-groove forming step of forming a sub-groove constituting portion formed of a main groove-side protruding piece protruding toward the main groove side on the upstream side in the axial direction, wherein the sub-groove forming step includes: The outer diameter of the auxiliary groove forming plug including the auxiliary groove forming blade is D _SP , when the outer diameter of the main groove forming plug is D _GP and the groove depth of the main groove forming plug is H _GP ,
(D _GP -2 × H _GP ) <D _SP <D _GP
The sub-groove formation plug is used, and the sub-groove formation plug is arranged between the sub-groove formation plug and the sub-groove formation pressing tool that is disposed outside the element tube and presses the element tube toward the sub-groove formation plug. After the subgroove formation first step of forming the first subgroove with only the plug and the subgroove formation first step, by pressing the element tube toward the subgroove formation plug with the subgroove formation pressing tool, The first sub-groove is further cut with the sub-groove forming blade and formed as the sub-groove, and a second sub-groove formation step is performed. In the first sub-groove formation step, the first sub-groove is formed into a blank tube. The sub-groove forming blade overlaps with the fin in the pipe diameter direction while being pulled out.

According to the heat transfer tube manufacturing method described above, in the sub-groove forming step, the base-side sub-groove is obtained by performing a two-step process of the sub-groove forming first step and the sub-groove forming second step. It is possible to form a heat transfer tube in which the sub-groove constituting portion in which the tip side sub-groove angle α ₂ is larger than the angle α ₁ is formed on the inner surface of the tube.

  Therefore, with the above-described configuration, it is possible to provide a method for manufacturing a heat transfer tube that can improve the heat transfer coefficient in the tube while suppressing an increase in pressure loss.

Further, as an aspect of the present invention, a notch ratio Z indicating a notch depth of the fin in the first step of forming the sub-groove that forms the first sub-groove by notching the fin with respect to the height of the fin. _SP

としたとき、前記副溝形成第１工程での前記切り欠き率Ｚ_ＳＰを０．１以上とすることができる。

When a, the notch rate Z _SP in the sub-groove formed first step can be 0.1 or more.

  With the above-described heat transfer tube manufacturing method, a heat transfer tube having an excellent in-tube heat transfer coefficient can be reliably and efficiently manufactured.

Specifically, the depth of the first sub-groove can be 0.1 or more with respect to the height of the fin, and by cutting such a first sub-groove in the sub-groove formation second step, wherein the minor groove arrangement portion can be reliably configured than the proximal-side sub groove angle alpha ₁ becomes the distal-side sub groove angle alpha ₂ increases shape.

In an embodiment of the present invention, the notch rate Z _SP in the sub-groove formed first step can be 0.6 or less.

  With the above-described configuration, it is possible to prevent the fin from being cut out too much, so that the first sub-groove is further cut in the sub-groove formation second step in the sub-groove formation second step than the first sub-groove in the fin. You can secure a bill.

Therefore, by further cutting the first sub-groove in the sub-groove formation second step, the sub-groove component portion has the tip-side sub-groove angle α ₂ larger than the base-side sub-groove angle α _1. It can be reliably configured to have a shape.

  In addition, since it is possible to prevent the fin from being cut out too much, the inner surface of the pipe is not damaged, and when the fin is cut out, the load on the auxiliary groove forming blade of the auxiliary groove forming plug is not excessively applied. The durability of the auxiliary groove forming plug can be improved without damaging the auxiliary groove forming blade of the auxiliary groove forming plug, which is generally expensive.

The present invention also includes a drawing means for drawing the raw pipe from the upstream side to the downstream side, and an inner surface fin forming groove on the outer periphery, crushing the inner surface of the pipe, and forming a spiral at a predetermined angle with respect to the pipe axis direction on the inner surface of the pipe. A main groove forming means having a main groove forming plug for forming a main groove between adjacent fins by forming a fin, and a secondary groove forming blade that intersects the fin at a predetermined crossing angle A sub-groove forming plug provided on the outer periphery, and a sub-groove forming pressing tool for pressing the raw tube toward the sub-groove forming plug, and forming the sub-groove in the fin. A main groove side projecting piece projecting to the main groove side on the upstream side in the tube axis direction is provided at the sub groove edge portion at the peripheral edge portion of the sub groove, and at least the upstream end portion in the fin forming direction at the sub groove edge portion. A heat transfer tube manufacturing apparatus comprising a sub-groove forming means for forming the sub-groove constituting portion provided A is, the sub-groove forming plugs, the outer diameter D _SP of the sub-groove formed plugs containing minor groove forming _blade, D _GP an outer diameter of the main groove forming _plug, groove depth of the main groove forming plug when was the _{H GP} is,
(D _GP -2 × H _GP ) <D _SP <D _GP
The sub-groove forming means forms the first sub-groove only by the sub-groove forming plug of the sub-groove forming plug and the sub-groove forming pressing tool on the upstream side of the sub-groove forming means. A first sub-groove is formed by pressing the element tube toward the sub-groove forming plug with the sub-groove forming pressing tool on the downstream side of the sub-groove first region in the sub-groove forming portion. A groove is further cut to form a sub-grooving second region to be formed as the sub-groove, and the sub-groove forming plug is disposed across the sub-groove first region and the sub-groove processing second region, The groove forming pressing tool is disposed only in the second sub-grooving region, out of the first sub-groove region and the second sub-groove region.

According to the heat transfer tube manufacturing apparatus described above, the sub-groove forming means forms the sub-groove in the fin by dividing the sub-groove processing first region and the sub-groove processing second region into two stages of regions. by, it is possible to manufacture the heat transfer tubes constitute than the proximal-side sub groove angle alpha ₁ becomes the distal-side sub groove angle alpha ₂ is larger shape wherein the minor groove arrangement portion in the tube surface.

  Therefore, with the above-described configuration, it is possible to provide a manufacturing apparatus that can manufacture a heat transfer tube that can improve the heat transfer coefficient in the tube while suppressing an increase in pressure loss.

  Here, the notch of the fin when forming the first sub-groove includes crushing the fin, and the first sub-groove when forming the sub-groove is the sub-groove forming blade. Further cutting in step includes further crushing the first sub-groove with the sub-groove forming blade.

  The heat transfer tube can be formed of a material having excellent thermal conductivity, such as copper, aluminum, or an alloy thereof.

  In addition, the range described using the character “kara” in the claims and the specification of the present invention includes a numerical value described before the symbol and a numerical value described after the symbol.

  According to the present invention, it is possible to provide a heat transfer tube, a manufacturing method thereof, and a manufacturing apparatus thereof capable of improving the heat transfer coefficient in the tube while suppressing an increase in pressure loss.

The partial expansion expansion perspective view which shows the heat exchanger tube of this embodiment. Sectional drawing which shows the structure of the subgroove structure part of this embodiment. The longitudinal cross-sectional view (a) which showed typically the heat exchanger tube of this embodiment, and the enlarged view (b) which showed typically the ridgeline part of a fin. Explanatory drawing which showed the manufacturing apparatus of the heat exchanger tube of this embodiment in the cross section. Explanatory drawing which showed the principal part of the manufacturing apparatus of the heat exchanger tube of this embodiment in cross section. Sectional drawing which shows the shape of the manufacture process of the heat exchanger tube of this embodiment. Schematic of the experimental apparatus used for the performance evaluation of the heat exchanger tube of this embodiment. Sectional drawing which shows the structure of the subgroove structure part of the conventional heat exchanger tube.

An embodiment of the present invention will be described below with reference to the drawings.
The heat transfer tube 1 in the present embodiment is formed as shown in FIGS. 1 to 3.

  1 (a) and 1 (b) are partially enlarged perspective views schematically showing the shape of the tube inner surface 10 of the heat transfer tube 1, and FIG. 2 (a) is a view of A in FIG. 1 (b). A cross-sectional view taken along line A, that is, the sub-groove constituting portion 6 that connects the second main groove-side protruding piece 5b and the third main groove-side protruding piece 5c across the sub-groove 7 described later, and the sub-groove constituting portion 6 FIG. 2B is a cross-sectional view of a part of the heat transfer tube 1 including fins 2 for two pitches on both sides in the AA line tube cross-sectional direction, and FIG. It is an enlarged view.

  FIG. 3A is a longitudinal sectional view of a part of the heat transfer tube 1 of the present embodiment, and FIG. 3B is an enlarged plan view of a part including the vicinity of the fin 2. . However, in FIG. 3A and FIG. 3B, the ridge line between the fin 2 and the sub-groove constituting portion 6 and the pipe inner surface 10 is schematically shown.

In the heat transfer tube 1, a spiral fin 2 having a predetermined angle with respect to the tube axis direction D <b> 1 is formed on the tube inner surface 10, a main groove 3 is formed between the fins 2, 2, and a sub-groove edge 4. And the main groove side protruding piece 5 are provided on the inner surface 10 of the pipe. The sub-groove edge 4 constitutes a peripheral portion of the concave sub-groove 7 formed in the fin 2. The main groove-side protruding piece 5 is configured to protrude from the sub-groove edge 4 on the side of the main groove 3 between the fins 2 and 2 adjacent to each other on the upstream side D1u in the tube axis direction.
The sub-groove constituting portion 6 is composed of a proximal-side sub-groove constituting portion 6A on the proximal end side in the protruding direction D3u from the pipe inner surface 10 and a distal-side sub-groove constituting portion 6B on the distal end side in the protruding direction D3u. (See FIG. 1 (b)).

Here, as shown in FIGS. 2 (a) and 2 (b), the base-side sub-groove of the sub-groove angle α formed by the sub-groove constituting portion 6 that faces the both sides of the fin forming direction D2 with the sub-groove 7 therebetween. the minor groove angle alpha formed by the configuration unit 6A, with a base end side auxiliary groove angle alpha _1, the sub-groove angle alpha formed by the distal end side auxiliary groove arrangement portion 6B, and the distal end side auxiliary groove angle alpha _2.

In this case, the sub groove arrangement portion 6 is formed at the distal end side auxiliary groove angle alpha ₂ is larger shape than the proximal end side auxiliary groove angle alpha _1.

The base end side auxiliary groove configuration section 6A, the base end side auxiliary groove angle alpha _1, is formed by 30 ° in the range of 10 ° to 90 °, the distal end side auxiliary groove arrangement portion 6B, the distal collateral groove angle alpha ₂ is formed of 110 ° in the range of 170 ° from 30 °.

  As shown in FIGS. 3A and 3B, the main groove-side protruding piece 5 is 5 with respect to the fin 2 on the side of the main groove 3 from the sub-groove edge 4 when the fin 2 is viewed in plan. It is formed with a projection angle β of 12 °, which is in the range of ° to 90 °.

The main groove-side protruding piece 5 has a ratio of 0.3 which is within a range of 0.1 to 0.9 with respect to the interval between the fins 2 and 2, that is, the width (W ₂ ) of the main groove 3. The projecting length (W ₁ ) is formed (see FIG. 1A).

  The sub-grooves 7 are formed in the spiral fin 2 with 32 strips in the range of 4 to 60 per tube circumference. The term “per tube circumference” means that it is one line of the spiral fin 2.

  Specifically, the heat transfer tube 1 of the present embodiment has an outer diameter of 7.0 mm, and the spiral fin 2 is formed at an angle (θ) of 30 ° with respect to the tube axis direction D1. Furthermore, the number of fins per tube circumference is 48, the tube inner surface fin height (main groove depth) is 0.25 mm, and the cross-sectional shape of the fin 2 is formed in a substantially trapezoidal shape. Further, the sub-groove 7 is formed with a sub-groove forming blade 28a described later having a height of 0.25 mm.

  The sub-groove constituting portion 6 forms sub-grooves 7 at substantially equal intervals along the fin forming direction D2 with respect to the fins 2, so that the sub-groove constituting portions 6 at substantially equal intervals along the fin forming direction D2 with respect to the fins 2. Forming.

  As shown in FIGS. 3A and 3B, the main groove side protruding piece 5 includes a first main groove side protruding piece 5a, a second main groove side protruding piece 5b, a third main groove side protruding piece 5c, and And 4th main groove side protrusion piece 5d (refer FIG.3 (b)).

The 1st main groove side protrusion piece 5a is the structure protruded from the upstream edge part 4u of the fin formation direction D2 in the sub groove edge part 4 to the main groove 3 of the pipe-axis direction upstream D1u.
The 2nd main groove side protrusion piece 5b is the structure protruded from the upstream edge part 4u of the fin formation direction D2 in the sub groove edge part 4 to the main groove 3 of the pipe-axis direction downstream D1d.
The 3rd main groove side protrusion piece 5c is the structure protruded from the downstream edge part 4d of the fin formation direction D2 in the sub groove edge part 4 to the main groove 3 of the pipe-axis direction upstream D1u.
The 4th main groove side protrusion piece 5d is the structure protruded from the downstream edge part 4d of the fin formation direction D2 in the sub groove edge part 4 to the main groove 3 of the pipe-axis direction downstream D1d.
The sub-groove constituting portion 6 is formed in a cross-sectional shape as shown in FIGS.
Specifically, the sub groove arrangement portion 6, as described above, than the proximal-side sub groove angle alpha ₁ is formed in the distal-side sub groove angle alpha ₂ increases shape. In other words, the sub-groove constituting portion 6 forms the base end-side sub-groove constituting portion 6A in a V shape in a sectional view, and the tip-side sub-groove constituting portion 6B is replaced with the tip portion of the base-end-side sub-groove constituting portion 6A. It is formed in the shape bent in the direction which spreads outside from.

  In other words, the second main groove side protruding piece 5b and the third main groove side protruding piece 5c are directed from the pipe inner surface 10 toward the pipe inner space H, that is, as shown in FIGS. 2 (a) and 2 (b). However, as it advances toward the tip with respect to the base in the protruding direction D3u, it is warped outward in the tube axis direction D1, which is opposite to the sub-groove 7, and is formed in a shape in which the distance between them is increased. ing.

Incidentally, the base-side sub groove angle alpha ₁ formed by the said base end side auxiliary groove configuration section 6A, FIG. 2 (a), (b) during the second main groove side protruding piece 5b and the third main groove side projecting piece 5c The sub-groove angle α formed between the base ends of the second main groove-side protruding piece 5b and the third main groove-side protruding piece 5c is shown.

On the other hand, the distal end side auxiliary groove angle alpha ₂ formed by the distal end side auxiliary groove arrangement portion 6B is FIG. 2 (a), the in (b), and a second main groove side protruding piece 5b and the third main groove side projecting piece 5c Of the sub-groove angles α formed, sub-groove angles α formed on the respective leading ends of the second main groove-side protruding piece 5b and the third main groove-side protruding piece 5c are shown.

Then, the manufacturing apparatus 11 which manufactures the heat exchanger tube 1 mentioned above as an internally grooved pipe is demonstrated using FIG. 4, FIG.
FIG. 4 is a schematic view showing a cross section of the manufacturing apparatus 11 for the heat transfer tube 1 in the present embodiment, and FIG. 5 is an enlarged view of the main groove forming plug 25 showing the X part and the Y part in an enlarged manner. It is explanatory drawing of the subgroove formation plug.

  The manufacturing apparatus 11 arranges the reduced diameter portion 13, the main groove processing portion 14, and the sub-groove processing portion 15 in this order along the drawing direction (X direction in FIG. 4), that is, from the upstream side to the downstream side in the drawing direction. Further, a drawing device 16 is provided on the further downstream side, and the inner tube 1a is continuously processed by these configurations to manufacture an internally grooved tube.

  When the extraction device 16 pulls out the raw tube 1a, the manufacturing apparatus 11 continuously processes the raw tube 1a by the plug body 20 disposed inside the tube and the tube placement jig 21 disposed outside the tube. Manufactures grooved tubes.

The plug body 20 includes a floating plug 23, a main groove forming plug 25, a sub groove forming plug 28, and a first connecting rod 27 and a second connecting rod 31 that connect them in series.
The outside-tube arrangement jig 21 includes a reduced diameter die 22, a rolled ball 26, a rolled ball holder 30, and a secondary groove forming die 29.

Hereinafter, the structure of each part mentioned above is demonstrated.
The diameter-reduced portion 13 is a portion for reducing the diameter of the passing raw tube 1 a, and includes a diameter-reduced die 22 and a floating plug 23. The diameter-reducing die 22 is formed in a cylindrical shape having a die hole 22a that opens in a divergent shape toward the upstream side D1u and penetrates in the tube axis direction D1, and the raw tube 1a is inserted into the die hole 22a. It arrange | positions on the outer side of the raw tube 1a.

  Further, the floating plug 23 is disposed inside the raw tube 1a, and a part of the outer peripheral surface in the axial direction is formed in a conical shape. Thereby, the floating plug 23 is engaged with the reduced diameter die 22 through the raw tube 1a so as to be rotatable around the tube axis.

  The main groove processing portion 14 includes a main groove forming plug 25, a plurality of rolling balls 26, and a rolling ball holder 30.

  The main groove forming plug 25 squeezes the tube inner surface 10 to form a spiral fin 2 having a predetermined angle with respect to the tube axis direction D1 on the tube inner surface 10, thereby forming a main groove between adjacent fins 2. A spiral inner fin forming groove 25a for forming the groove 3 is provided on the outer periphery.

  The main groove forming plug 25 is configured with a lead angle of 40 ° in the right twist direction with respect to the tube axis direction D1.

  A plurality of rolling balls 26 are arranged on the outside of the raw tube 1a so as to be able to roll while pressing the raw tube 1a, that is, to be rotatable and revolve around the tube axis.

  The rolling ball holder 30 is a jig for holding the rolling ball 26, and includes an upstream rolling ball holder 30U disposed on the upstream side and a downstream rolling ball holder 30D disposed on the downstream side. It consists of and.

  The upstream rolling ball holder 30U is configured in a cylindrical shape having a communication hole 30a that communicates in the drawing direction X and opens toward the downstream side in the drawing direction X. The downstream side rolled ball holder 30D is a cylindrical member having an L-shaped cross section.

  A first connecting rod 27 is disposed as a first connecting means between the reduced diameter portion 13 and the main groove processing portion 14, and the first connecting rod 27 includes the main groove forming plug 25 and the floating plug 23. Are independently pivotably connected.

The sub groove processing portion 15 includes a sub groove forming plug 28 and a sub groove forming die 29.
The upstream side D1u in the sub-grooving section 15 is defined as a sub-groove processing first area Z1, and the downstream side of the sub-groove processing first area Z1 in the sub-groove processing section 15 is defined as a sub-groove processing second area Z2. .

  The sub-grooving first region Z1 is a region in which the first sub-groove 7A (see FIG. 6) is formed only by the sub-groove forming plug 28 out of the sub-groove forming plug 28 and the sub-groove forming die 29. The second groove processing region Z2 is a region in which the first sub-groove 7A is formed as the sub-groove 7 by pressing the raw tube 1a toward the sub-groove forming plug 28 with the sub-groove forming die 29.

  That is, the sub-groove forming plug 28 is arranged over both the sub-groove processing first region Z1 and the sub-groove processing second region Z2, and the sub-groove forming die 29 is connected to the sub-groove processing first region Z1. It arrange | positions only in the subgroove process 2nd area | region Z2 among the subgroove process 2nd area | region Z2.

  The sub-groove forming plug 28 includes a spiral sub-groove forming blade 28 a that intersects the fin 2 at a predetermined crossing angle on the outer periphery.

  As shown in FIG. 5, the sub-groove forming plug 28 is arranged so that the fin 2 protruding from the inner surface 10 of the pipe and the sub-groove forming plug 28 overlap in the pipe radial direction inside the raw tube 1a (in FIG. 5). , See enlarged view of portion Y).

Specifically, the sub-grooves formed plug 28, the outer diameter of the sub-groove forming plug 28 that includes a minor groove forming blade 28a _{D SP,} the outer diameter of the main groove forming plug 25 including the inner surface fin forming grooves 25a _{D GP,} main grooves when the groove depth of the forming plug 25 (inner surface fin height) was H _GP,
(D _GP -2 × H _GP ) <D _SP <D _GP
It is configured to satisfy the range of

More specifically, the notch ratio Z _SP indicating the notch depth of the fin 2 in the first step of forming the sub-groove that forms the first sub-groove 7A by notching the fin 2 with respect to the fin height,

としたとき、前記副溝形成第１工程での前記切り欠き率Ｚ_ＳＰが０．１から０．６の範囲内となるよう設定している。

In this case, the notch ratio Z _{SP in} the first sub-groove forming step is set to be in the range of 0.1 to 0.6.

In this embodiment, the outer diameter of the minor groove forming plug 28, except for the minor groove forming blade 28a as well as composed of 7.25 mm, an outer diameter _{D SP} of the sub-grooves formed plug 28, including the minor groove forming blade 28a 7 .75mm.

  The minor groove forming blade 28a (notched blade) is configured with a lead angle of 30 ° in the right twist direction with respect to the tube axis direction D1. Further, the auxiliary groove forming blade 28a is formed with a height of 0.25 mm and an apex angle of 30 °, and the apex portion is formed flat.

  The sub-groove forming die 29 is arranged outside the base tube 1a as a sub-groove forming pressing tool for pressing the base tube 1a toward the sub-groove forming plug 28.

  A second connecting rod 31 is arranged as a second connecting means between the main groove processing portion 14 and the sub groove processing portion 15, and the second connecting rod 31 is composed of the main groove forming plug 25 and the sub groove forming plug. 28 are connected to each other in a rotatable manner.

  The above-described drawing device 16 includes a winding drum 32 and a winding motor M1, and the inner grooved tube 11 is wound around the winding drum 32 while being pulled by the rotation of the motor M1.

  In addition, the said manufacturing apparatus 11 may be equipped with the diameter adjustment die between the subgroove processing part 15 and the drawing apparatus 16 (not shown). The sizing die is for smoothening, for example, distortion of the tube surface caused by pressing of the rolling ball 26 in the groove processing portion 14 when the heat transfer tube passes through the die hole penetrating in the tube axis direction D1. This is a die for adjusting the diameter.

The heat transfer tube 1 of this embodiment is manufactured by the following manufacturing method using the manufacturing apparatus 11 described above.
The heat transfer tube 1 is manufactured by continuously performing the diameter reducing step, the main groove forming step, and the sub-groove forming step on the raw tube 1a while the raw tube 1a is drawn from the upstream side to the downstream side by the drawing device 16. .

  The diameter reducing step is a step of reducing the diameter of the raw tube 1 a by the first diameter reducing die 22 and the floating plug 23 in the diameter reducing portion 13.

  In the main groove forming step, the pipe inner surface 10 is crushed by the main groove forming plug 25 provided with the inner surface fin forming groove 25a on the outer periphery in the main groove processing portion 14, and the pipe inner surface 10 is crushed at a predetermined angle with respect to the pipe axis direction D1. This is a step of forming the main groove 3 between the adjacent fins 2 and 2 by forming the spiral fin 2.

  In the sub-groove forming step, the sub-groove 7 is formed in the fin 2 by the sub-groove forming plug 28 in the sub-groove processing portion 15, so that the sub-groove edge 4 and the at least first main groove at the peripheral portion of the sub-groove 7 This is a step of forming the sub-groove constituting portion 6 constituted by the side protruding pieces 5a.

In the sub-groove forming step, the sub-groove forming first step and the sub-groove forming second step are continuously performed.
In the first sub-groove formation step, the first sub-groove 7 </ b> A is formed by only the sub-groove formation plug 28 out of the sub-groove formation plug 28 and the sub-groove formation die 29.

Specifically, in the minor groove forming the first step, 4, and, as shown in FIG. 5, as described above in the minor groove machining first region Z _1,
(D _GP -2 × H _GP ) <D _SP <D _GP
Only the sub-groove forming plug 28 satisfying the above-mentioned range is processed, and the sub-groove forming die 29 pulls the raw pipe 1a without pressing the sub-tube 1a toward the sub-groove forming plug 28 side.

  The sub-groove forming plug 28 is arranged so that the fin 2 protruding from the inner surface 10 of the pipe and the sub-groove forming plug 28 overlap in the pipe radial direction inside the raw tube 1a (in FIG. 5, an enlargement of the Y portion). As shown in FIGS. 6 (a) and 6 (b), the sub-groove forming blade 28a cuts out the fin 2 to form the first sub-groove 7A in the fin 2 by pulling out the raw tube 1a. Such a first sub-groove constituting portion 6 </ b> A is formed in the fin 2.

As a result, the first sub-groove 7A is notched so that the notch ratio Z _SP indicating the notch depth of the fin 2 satisfies the range of 0.1 to 0.6.

At this time, as shown in FIG. 6B, the first sub-groove constituting portion 6 has a base-side sub-groove angle α ₁ and a tip-side sub-groove angle α ₂ that are substantially the same size. The side protrusion piece 5b and the third main groove side protrusion piece 5c form a V-shape in a sectional view.

In the sub-groove formed second step, by pressing the blank tube 1a to the minor groove formed plug 28 side by side grooves formed die 29 in the minor groove machining a second region Z _2, a first auxiliary groove 7A, the minor groove formed blade Further cut by 28a to form the sub-groove 7.

  At this time, by cutting the first sub-groove 7A with the sub-groove forming blade 28a, the first sub-groove constituting portion 6A having a V-shaped cross-sectional view may be the sub-groove constituting portion 6 having the above-described configuration. it can.

That is, as shown in FIGS. 2A and 2B, the sub-groove constituting portion 6 including the second main groove-side protruding piece 5b and the third main groove-side protruding piece 5c is protruded from the pipe inner surface 10 in the protruding direction D3u. While projecting, bent warp outward a minor groove 7 taken to proceed to the distal end with respect to each base opposite side, a shape widened distance therebetween, the distal end side vice than base end side auxiliary groove angle alpha ₁ groove angle alpha ₂ is larger shape.

The heat transfer tube 1 described above can obtain various actions and effects as follows.
In the heat transfer tube 1 described above, the sub-groove constituting portion 6 provided on the tube inner surface 10 is formed in a shape in which the distal-side sub-groove angle α ₂ is larger than the proximal-side sub-groove angle α _1, thereby FIG. As shown in (a) and (b), the sub-groove constituting portion 101 having a shape in which the base-side sub-groove angle α ₁ and the tip-side sub-groove angle α ₂ are substantially the same size is formed on the pipe inner surface 10. Compared with the conventional heat transfer tube 100, it is possible to promote turbulent flow including the inside of the refrigerant in the radial direction of the tube.
Therefore, the heat transfer tube 1 can improve the heat transfer coefficient in the tube while suppressing an increase in pressure loss.
8A corresponds to FIG. 2A, and shows a cross-sectional view of the conventional heat transfer tube 100, and FIG. 8B shows an enlarged view of a portion X in FIG. 8A. Yes.

Specifically, in a conventional heat transfer tube in which a sub-groove constituting portion having a shape in which the base-side sub-groove angle α ₁ and the tip-side sub-groove angle α ₂ are substantially the same size is formed on the tube inner surface 10, 8 (a) and 8 (b), there is a heat transfer tube 100 in which the sub-groove constituting portion 101 including the main groove-side protruding piece 102 is formed on the tube inner surface 10.

  Such a conventional heat transfer tube 100 is provided with the main groove side protruding piece 102, so that a part of the refrigerant flowing between the fins 2 and 2 collides with the main groove side protruding piece 5, and the tube radial direction. By being lifted inward, a three-dimensional unsteady flow can be effectively generated.

  Therefore, in the conventional heat transfer tube 100, there is also a tube in which the number of the main groove side protruding pieces 102 is increased on the tube inner surface 10 for the purpose of improving the effect of providing the main groove side protruding pieces 102 on the tube inner surface 10. .

However, when the number of sub-groove constituent portions 101, in particular, the main groove-side protruding pieces 102, is simply increased in the fin 2 on the tube inner surface 10, the pressure loss increases, and conversely, the heat transfer coefficient in the tube decreases. Problems arise.
For this reason, the configuration of the conventional heat transfer tube 100 has a limit in improving the heat transfer coefficient in the tube beyond a predetermined level.

  Furthermore, in order to increase the number of the main groove side protruding pieces 102 on the pipe inner surface 10, it is necessary to form the auxiliary grooves 103 in the fins 2 accordingly, and it becomes impossible to secure the strength of the fins 2 that can withstand mechanical expansion. Another problem is that it is difficult to form the sub-grooves 103 in the fin 2 at a narrow pitch due to the limitation on the performance of the processing apparatus, and the number of the main groove-side protruding pieces 102 cannot be simply increased. It was.

On the other hand, the heat transfer tube 1 of the present embodiment pays attention to the shape rather than the number of the sub-groove constituting portions 6, and the sub-groove constituting portion 101 provided on the inner surface of the conventional heat transfer tube 100 has the base end side sub-groove. Whereas the angle α ₁ and the distal side secondary groove angle α ₂ have substantially the same size (see FIG. 8 (b)), the secondary groove constituting portion 6 is changed to the proximal side secondary groove angle α _1. tip collateral groove angle alpha ₂ is formed in larger shape than (see Figure 2 (b)). Thereby, when a part of the refrigerant flowing between the fins 2 and 2 collides with the sub-groove constituting portion 6, particularly the main groove-side protruding piece 5, a more complicated refrigerant turbulent effect can be obtained.

Furthermore, it is possible to derive a large amount of refrigerant by larger the distal end side auxiliary groove arrangement portion 6B of the front end side auxiliary groove angle alpha ₂ to the minor groove 7, the refrigerant flows easily into the tube axis direction D1, the pressure loss The impact can also be mitigated.

  Therefore, the heat transfer tube 1 of the present embodiment can further improve the heat transfer coefficient in the tube of the conventional heat transfer tube 100, which is the limit only by forming a large number of sub-grooves 7 (, 103) in the fin 2. Therefore, an excellent in-tube heat transfer coefficient can be obtained without being adversely affected by forming a large number of sub-grooves 7 (, 103) in 2 and restrictions on processing.

As described above, the sub-groove constituting portion 6 has the base-side sub-groove angle α ₁ in the configuration in which the tip-side sub-groove angle α ₂ is larger than the base-side sub-groove angle α ₁ . from 10 ° and 30 ° in the range of 90 °, it is formed so as to be distal side 110 ° the minor groove angle alpha ₂ in the range of 170 ° from 30 °.
Thereby, the heat transfer coefficient in a pipe | tube can be improved, suppressing the increase in pressure loss.

Further, the sub-groove constituting portion 6 has durability so that the proximal-side sub-groove constituting portion 6A and the distal-end-side sub-groove constituting portion 6B are not damaged even if pressure due to the collision of the refrigerant continues to be applied. It can be, also, like the sub groove forming portion 6 is prevented from breaking during processing, strength plane, from the processed surface, the angle balance between the proximal end side auxiliary groove angle alpha ₁ and the distal end side auxiliary groove angle alpha ₂ It can be configured in a suitable shape.

  Further, the heat transfer tube 1 has the main groove side protruding piece 5 formed with a protruding angle (β) of 12 ° which is within a range of 5 ° to 90 ° with respect to the fin 2, and thus flows through the main groove 3. Since a part of the refrigerant can collide with the main groove-side protruding piece 5 and flow into the sub-groove 7 from the main groove-side protruding piece 5 without excessively obstructing the flow of the refrigerant, a larger refrigerant stirring action Thus, the heat transfer rate can be improved.

  Furthermore, the heat transfer tube 1 can prevent an increase in pressure loss because the refrigerant flow rate in the tube axis direction D1 increases.

Further, by forming the main groove side protruding piece 5 with a protruding length (W ₁ ) of 0.3 which is a ratio of 0.1 or more with respect to the interval (W ₂ ) between the fins 2 and 2. In addition, a part of the refrigerant flowing through the main groove 3 can collide with the main groove side protruding piece 5 to promote turbulent flow including the inner side in the pipe radial direction, and the heat transfer coefficient can be improved by a larger refrigerant stirring action. be able to. Furthermore, since the refrigerant can flow from the main groove side protruding piece 5 into the sub groove 7 and the refrigerant flow rate in the tube axis direction D1 increases, an increase in pressure loss can be prevented.

The main groove-side protruding piece 5 is formed with a protruding length (W ₁ ) having a ratio of 0.3 which is 0.9 or less with respect to the interval (W ₂ ) between the fins 2 and 2. Therefore, the influence of the pressure loss due to the formation of the main groove-side protruding piece 5 can be reduced.

  By forming the sub-groove 7 with 32 which is a number of 4 to 60 per pipe circumference, the interval in the fin forming direction D2 between the adjacent sub-grooves 7 formed in the fin 2 does not become too large, and sufficient refrigerant stirring is performed. While the effect can be obtained, it is possible to ensure the fin strength that can withstand the mechanical expansion.

According to the manufacturing method of the heat transfer tube 1 described above, in the sub-groove forming step, the base-side sub-groove angle α is obtained by performing a two-step process including a sub-groove forming first step and a sub-groove forming second step. ₁ can also be the distal end side auxiliary groove angle alpha ₂ to form the sub-groove arrangement portion 6 serving as a larger shape to inner surface 10 from the heat transfer tubes 1 serving as the above-mentioned excellent tube heat transfer coefficient, reliably, and Can be manufactured efficiently.

Specifically, in the first step of forming the sub-groove, the first sub-groove 7 </ b> A can be formed only by the sub-groove forming plug 28 without pressing the element tube 1 a toward the sub-groove forming plug 28 by the sub-groove forming die 29. it can.
In the second sub-groove formation step, the first sub-groove 7A formed in the fin 2 in the sub-groove formation first step is cut while pressing the element tube 1a toward the sub-groove formation plug 28 by the sub-groove forming die 29. This is a step of forming the sub-groove 7. For this reason, compared with the case where the subgroove 7 is newly formed in a single process on the fin 2 in which the first subgroove 7A is not formed, the load that presses the raw tube 1a by the subgroove forming die 29 The sub-groove 7 can be formed in the fin 2 with a significant relaxation.

  Accordingly, the sub-groove forming process can greatly reduce the load applied to the raw tube 1a by going through the two-stage process of the sub-groove forming first process and the sub-groove forming second process. The raw tube 1a can be smoothly pulled out, and the heat transfer tube 1 can be manufactured reliably and efficiently without disconnection during the drawing.

In the method of manufacturing the heat transfer tube 1, the notch ratio Z _SP indicating the notch depth of the fin 2 in the first step of forming the sub-groove that forms the sub-groove 7 by notching the fin 2 with respect to the fin height. The

としたとき、副溝形成第１工程での前記切り欠き率Ｚ_ＳＰを０．１以上としたため、第１副溝７Ａの深さを前記フィン２の高さに対して０．１以上とすることができる。

When the order of the notch factor Z _SP in the minor groove forming the first step was 0.1 or more and 0.1 or more the depth of the first sub-grooves 7A relative to the height of the fin 2 be able to.

Thus, by cutting such a first auxiliary groove 7A in the sub-grooves formed second step, the sub groove arrangement portion 6, increases the tip-side sub groove angle alpha ₂ than the base end side auxiliary groove angle alpha ₁ It can be reliably configured to have a shape.

In the manufacturing method of the heat transfer tube 1, as described above, by the notch ratio Z _SP in the minor groove forming the first step and 0.6 or less, it is possible to prevent the excessive notched fins 2 Further, a cutting margin can be secured in order to further cut the first sub-groove 7A in the sub-groove formation second step on the base side of the fin 2 than the first sub-groove 7A.

Therefore, by by the sub-grooves formed second step cuts the first sub-grooves 7A, the minor groove arrangement portion 6, the front end side auxiliary groove angle alpha ₂ is larger shape than the proximal end side auxiliary groove angle alpha ₁ It can be configured reliably.

  Further, since it is possible to prevent the fin 2 from being cut out too much, the inner surface 10 of the pipe is not damaged, and when the fin 2 is cut out, the sub groove forming blade 28a of the sub groove forming plug 28 is overloaded. The secondary groove forming blade 28a of the secondary groove forming plug 28, which is generally expensive, is not damaged, and the durability can be improved.

  Although the heat transfer tube 1 according to the embodiment of the present invention has been described in detail above, a performance verification experiment conducted for verifying the performance of the heat transfer tube of the present invention will be described.

In this experiment, two types of heat transfer tubes of Examples 1 and 2 were prepared as the heat transfer tubes of the present invention, and two types of heat transfer tubes of Conventional Examples 1 and 2 were formed as the conventional heat transfer tubes 100, respectively.
The heat transfer tubes of Examples 1 and 2 and the heat transfer tubes of Conventional Examples 1 and 2 are manufactured in a shape having an outer diameter, fins, number of sub-grooves, and sub-groove constituent parts as shown in Table 1.

詳しくは、従来例１の伝熱管は、管内面１０のフィン２に副溝７が形成されていない。すなわち、副溝７によって副溝構成部６も管内面１０に形成されていない伝熱管である。
従来例２の伝熱管は、図８（ａ），（ｂ）に示すように、管内面１０のフィン２に副溝１０３が形成され、副溝縁部と主溝側突出片１０２とで構成した副溝構成部１０１を管内面１０に備えている伝熱管１００であり、副溝構成部１０１は、基端側副溝角度α_１と先端側副溝角度α_２とを略同じ大きさで形成している。

Specifically, in the heat transfer tube of Conventional Example 1, the secondary groove 7 is not formed in the fin 2 on the tube inner surface 10. That is, the secondary groove 7 is a heat transfer tube in which the secondary groove constituting portion 6 is not formed on the tube inner surface 10.
As shown in FIGS. 8A and 8B, the heat transfer tube of Conventional Example 2 includes a sub-groove 103 formed in the fin 2 on the inner surface 10 of the tube, and includes a sub-groove edge and a main groove-side protruding piece 102. minor groove arrangement portion 101 that is a heat transfer tube 100 is provided on the inner surface 10, the minor groove arrangement portion 101, a proximal end side auxiliary groove angle alpha ₁ and the distal end side auxiliary groove angle alpha ₂ substantially the same size Forming.

On the other hand, as shown in FIGS. 2A and 2B, the heat transfer tubes of Examples 1 and 2 each have a sub-groove configuration constituted by the sub-groove edge 4 and the main groove-side protruding piece 5. comprising a unit (6) to the inner surface 10, are formed at the distal end side auxiliary groove angle alpha ₂ is larger shape than the proximal end side auxiliary groove angle alpha _1.

Specifically, the heat transfer tube of the first embodiment, a 30 ° a base end side auxiliary groove angle alpha ₁ in the range from 10 ° to 90 °, the distal end side auxiliary groove angle alpha ₂ is 170 ° from the 30 ° It is 110 degrees which is in the range. Heat transfer tube of Example 2 is 30 ° a base end side auxiliary groove angle alpha ₁ in the range from 10 ° to 90 °, the distal end side auxiliary groove angle alpha ₂ is within the range of 170 ° from the 30 ° 130 °.

  The heat transfer tubes of Examples 1 and 2 are respectively produced by the same manufacturing method as the heat transfer tube of the above-described embodiment. In particular, the heat transfer tubes of Example 1 are also apparent from the shapes of the respective parts shown in Table 1. As is apparent, a heat transfer tube having the same shape as the heat transfer tube 1 of the above-described embodiment is used.

  Moreover, the heat transfer tube of the prior art example 1 is created using the manufacturing apparatus 11 provided with the main groove forming plug 25 having a shape as shown in Table 2, and the heat transfer tube of the first and second embodiments and the prior art example 2 The heat transfer tubes were produced using a manufacturing apparatus provided with a main groove forming plug 25 having a shape shown in Table 2 and a sub groove forming plug 28 having a shape shown in Table 3, respectively.

  That is, as shown in Table 2, the main groove forming plug 25 uses the same form for each of the heat transfer tubes of Examples 1 and 2 and the heat transfer tubes of Conventional Examples 1 and 2, and Table 3 As shown, the sub-groove forming plugs 28 were manufactured in different forms, and appropriate heat transfer tubes were produced.

Note that the outer diameter D _SP of the sub groove forming plugs 28 in Table 3 shows the outer diameter including the height of the sub-groove forming blades 28a, minor groove formed with the radial direction of the ends of the sub groove forming plugs 28 The distance between the straight lines connecting the tops of the blades 28a so as to pass through the center of the auxiliary groove forming plug 28 is shown.

In this experiment, a condensation experiment for verifying the condensation performance in the tube of the heat transfer tube is performed using the in-tube condensation performance measuring device 42A as shown in FIG. 7A, and an evaporation experiment for verifying the evaporation performance is performed in FIG. This was performed using an in-tube evaporation performance measuring device 42B as shown in FIG.
FIGS. 7A and 7B are schematic views of the in-pipe condensing performance measuring device 42A and the in-pipe evaporating performance measuring device 42B, respectively. In any of the devices 42A and 42B, the whole is similar to a general air conditioner. Is constituted by a refrigeration cycle.

  Specifically, in the condensation experiment, each of the heat transfer tubes of Examples 1 and 2 and the heat transfer tubes of Conventional Examples 1 and 2 was incorporated as a test tube 44 in the condenser as shown in FIG. In this case, the heat transfer tube of the conventional example 1 is used as a comparison target of the heat transfer tubes of the first and second examples and the heat transfer tube of the conventional example 2, and the heat transfer tubes of the first and second examples with respect to the heat transfer tube 1 of the conventional example 1. Condensation performance was verified by measuring the ratio of heat transfer coefficient (heat transfer coefficient ratio) and the ratio of pressure loss (pressure loss ratio) to the heat transfer tubes 1 of Example 1 and Conventional Example 2.

  In the evaporation experiment, each of the heat transfer tubes 1 of Examples 1 and 2 and the heat transfer tubes 1 of Conventional Examples 1 and 2 were incorporated as test tubes 44 in the evaporator as shown in FIG. In this case, the heat transfer tube 1 of the conventional example 1 is used as a comparison object of the heat transfer tubes of the first and second embodiments and the heat transfer tube of the conventional example 2, and the heat transfer tubes of the first and second embodiments with respect to the heat transfer tube of the conventional example 1. And, the evaporation performance was verified by measuring the ratio of the heat transfer coefficient (heat transfer coefficient ratio) and the ratio of pressure loss (pressure loss ratio) to each of the heat transfer tubes of Conventional Example 2.

As shown in FIGS. 7A and 7B, the test sections in the in-tube condensing performance measuring device 42A and the in-tube evaporating performance measuring device 42B are constituted by a double-tube heat exchanger, and are provided in the test tube 44. An effective length of the test tube 44 is obtained by flowing heat exchange water (hereinafter referred to as “heat exchange water”) in a direction opposite to the refrigerant flow in the annular portion 45 constituting the outer shell. Heat was exchanged with the thickness set to 4 m.
Note that low-temperature water is flowed as heat exchange water in the condensation experiment, and high-temperature water is flowed as heat exchange water in the evaporation experiment.

  Further, as shown in FIGS. 7A and 7B, a thermometer, a pressure gauge, and a flow meter are arranged at each predetermined portion of the test section. 7A and 7B, T is a thermometer, P is a pressure gauge, and G is a flow meter.

  Subsequently, as the experimental conditions at the refrigerant inlet and outlet of the test tube 44, in the condensation experiment, the refrigerant inlet superheat degree, the refrigerant outlet supercooling degree, and in the evaporation experiment, the refrigerant inlet dryness, the refrigerant outlet superheat degree, respectively. Settings were made as shown in Table 4.

これら凝縮実験、蒸発実験における実験条件は、いずれも空調機の熱交換器入口条件と同一となるように、水温を調節した後に測定を行った。
さらにまた、供試管４４の入口と出口における冷媒平均飽和温度は、表４に示すように凝縮実験では４８℃に設定するとともに、蒸発実験では５℃に設定した。

Measurement was performed after adjusting the water temperature so that the experimental conditions in these condensation experiments and evaporation experiments were the same as the heat exchanger inlet conditions of the air conditioner.
Furthermore, as shown in Table 4, the average refrigerant saturation temperature at the inlet and outlet of the test tube 44 was set to 48 ° C. in the condensation experiment and 5 ° C. in the evaporation experiment.

As the refrigerant, R410A is used as an alternative chlorofluorocarbon, and since this R410A is a mixed refrigerant, the refrigerant is collected at the refrigerant sampling section (see FIGS. 7A and 7B) installed at the compressor outlet during the experiment. The sample was collected and experimented while measuring the refrigerant composition ratio by gas chromatography.
The analysis result of gas chromatography is reflected in ts1 and ts2 described later by calculation.

The pressure loss ratio and the heat transfer coefficient ratio αi in the test tube 44 showing the condensation performance and the evaporation performance are obtained as follows.
First, the pressure loss ratio in the tube is obtained as the pressure difference between the inlet and outlet of the test tube 44. The heat transfer coefficient ratio αi in the tube is calculated using the equations (1) to (4) based on the measured values in this experiment.

ここで、数式（１）中のＱは、交換熱量（ｋＷ）、Ａは、供試管外表面積（ｍ２）、ｔｍは、対数平均温度（℃）、αｏは、管外熱伝達率（ｋＷ／ｍ^２Ｋ）を示す。

Here, in Equation (1), Q is the amount of exchange heat (kW), A is the external surface area (m2) of the test tube, tm is the logarithmic average temperature (° C.), αo is the external heat transfer coefficient (kW / m ² K).

  In Equation (2), G is a flow rate of heat exchange water (kg / s), Cp is a specific heat (kJ / kgK) of heat exchange water, tw1 is an inlet temperature (° C.) of heat exchange water, and tw2 is Shows the outlet temperature (° C) of water for heat exchange.

  In Formula (3), ts1 indicates the refrigerant inlet saturation temperature (° C.), and ts2 indicates the refrigerant outlet saturation temperature (° C.).

  In Equation (4), k represents the thermal conductivity (kw / mK) of heat exchange water, and De represents the annular portion equivalent diameter (m). D represents the shell inner diameter (m), d represents the test tube outer diameter (m), Re represents the Reynolds number (−) of the heat exchange water, and Pr represents the Prandtl number (−) of the heat exchange water.

  That is, based on measured values such as temperature and setting parameters, Q is calculated from Formula (2), tm at the time of condensation and evaporation is calculated from Formula (3), and αo is calculated from Formula (4). By substituting in (1), the heat transfer coefficient ratio αi can be calculated.

  The evaluation results of the condensation performance and evaporation performance thus obtained are shown in Table 5.

表５の実験結果より明らかなように、フィン２に副溝７を形成していない従来例１の伝熱管に対して、フィン２に副溝７，１０３を形成したいわゆるクロス溝付の伝熱管とも称される実施例１，２の伝熱管、及び、従来例２の伝熱管の方が加工負荷の値が高くなった。これは、伝熱管の製造装置に副溝加工部を配置したためであると考えられる。

As is clear from the experimental results in Table 5, a heat transfer tube with a so-called cross groove in which the sub-grooves 7 and 103 are formed in the fin 2 in contrast to the heat transfer tube of the conventional example 1 in which the sub-groove 7 is not formed in the fin 2. The heat transfer tubes of Examples 1 and 2, which are also called, and the heat transfer tube of Conventional Example 2 have higher processing load values. This is considered to be because the sub-grooving portion was arranged in the heat transfer tube manufacturing apparatus.

  However, focusing on the heat transfer tubes of Examples 1 and 2 and the heat transfer tubes of Conventional Example 2, the values of the heat transfer tubes of Examples 1 and 2 are smaller than the heat transfer tubes of Conventional Example 2 with respect to the processing load. became. In particular, the processing load of the heat transfer tube of Example 2 was significantly smaller than the processing load of the heat transfer tube of Conventional Example 2.

  Thereby, the effectiveness of the manufacturing method which performs the subgroove formation process mentioned above in two steps, a subgroove formation 1st process and a subgroove formation 2nd process, was able to be verified.

  Further, as is clear from the experimental results in Table 5, in any of the heat transfer tubes of Examples 1 and 2 and the heat transfer tube of Conventional Example 2, the condensation performance and the evaporation performance of the heat transfer tube of Conventional Example 1 The heat transfer coefficient ratio for each of them has improved significantly.

  Accordingly, the sub-grooves 7 and 103 are formed in the fin 2 of the pipe inner surface 10, and the sub-groove constituting parts 6 and 101 constituted by the sub-groove edge 4 and the main groove side protruding pieces 5 and 102 are formed on the pipe inner surface 10. As an effect of the provision of the refrigerant, a part of the refrigerant flowing through the main groove 3 collides with the first projecting piece 5a and is scooped up in the pipe radial direction. It was confirmed that turbulent flow can be promoted.

  In particular, when comparing the heat transfer tubes of Examples 1 and 2 with the heat transfer tubes of Conventional Example 2, the values of the heat transfer tubes of Examples 1 and 2 are generally the same as those of Conventional Example 2 in terms of condensation performance and evaporation performance. The result was an improvement over the value of the heat tube.

  Specifically, when the heat transfer tube of Example 1 and the heat transfer tube of Conventional Example 2 are compared, as shown in Table 5, with respect to the pressure loss ratio, the condensation performance of the heat transfer tube of Conventional Example 2 is “99.3” and the evaporation performance. Was “99.4”, while the condensation performance of the heat transfer tube of Example 1 was “99.4” and the evaporation performance was “99.5”. On the other hand, regarding the heat transfer coefficient ratio, the condensation performance of the heat transfer tube of Conventional Example 2 is “108.4” and the evaporation performance is “110.7”, whereas the condensation performance of the heat transfer tube of Example 1 is “ 109.5 ”and the evaporation performance was“ 111.3 ”.

  As is clear from these results, the heat transfer tube of Example 1 was slightly higher in pressure loss ratio on the order of 0.1 than the heat transfer tube of Conventional Example 2, but for the heat transfer coefficient ratio, It was significantly higher on the order of 1.0 or more.

  Further, when comparing the heat transfer tube of Example 2 and the heat transfer tube of Conventional Example 2, as shown in Table 5, regarding the pressure loss ratio, the condensation performance of the heat transfer tube of Conventional Example 2 is “99.3” and the evaporation performance is In contrast to “99.4”, the condensation performance of the heat transfer tube of Example 2 was “100.2” and the evaporation performance was “101.3”. On the other hand, regarding the heat transfer coefficient ratio, the condensation performance of the heat transfer tube of Conventional Example 2 is “108.4” and the evaporation performance is “110.7”, whereas the condensation performance of the heat transfer tube of Example 1 is “ 111.2 "and the evaporation performance was" 113.5 ".

  As is clear from these results, the heat transfer tube of Example 2 has a higher pressure loss ratio than the heat transfer tube of Conventional Example 2, but the heat transfer coefficient ratio is higher than the increase in the pressure loss ratio. Significantly higher value.

From this, the number of sub-grooves 7, the length of the main groove side protruding piece 5 with respect to the main groove width (W ₁ / W ₂ ), and the angle (β) formed by the main groove side protruding piece 5 with respect to the fin 2 are the same. On the condition, like the heat transfer tube of the conventional example 2, the sub-groove constituting portion is formed in a shape in which the base-side sub-groove angle α ₁ and the tip-side sub-groove angle α ₂ are substantially the same size. Thus, as in the heat transfer tubes of Examples 1 and 2, the condensing performance and the evaporation performance are further improved by forming the tip side sub groove angle α ₂ larger than the base end side sub groove angle α ₁ . I was able to prove that

Specifically, the heat transfer tube of Conventional Example 2 has 32 sub-grooves, and the sub-grooves 7 are densely formed with a relatively narrow pitch with respect to the fins 2 in the fin forming direction D2.
In the case of such a configuration, in order to improve the condensation performance and the evaporation performance, when the number of the auxiliary grooves 7 formed in the fin 2 is simply further increased, the pressure loss ratio becomes large, and conversely, the heat transfer coefficient in the pipe It has already been demonstrated that the ratio drops. That is, in the configuration of the heat transfer tube of Conventional Example 2, there is a limit to further improve the condensation performance and the evaporation performance.

On the other hand, like the heat transfer tubes of Examples 1 and 2, by forming the sub-groove constituting portion 6 in a shape in which the front-end side sub-groove angle α ₂ is larger than the base-end side sub-groove angle α ₁ , It was proved that both the condensation performance and the evaporation performance can be further improved.

In the correspondence between the configuration of the present invention and the above-described embodiment,
The sub-groove forming pressing tool corresponds to the rolling ball 26, and similarly,
The extraction means corresponds to the extraction device 16,
The main groove forming means corresponds to the main groove processing portion 14,
The sub-groove forming means corresponds to the sub-groove processing portion 15, but the present invention is not limited to the above-described embodiment, and can be configured in various embodiments.

  For example, the sub-groove constituting portion 6 has, as the main groove-side protruding piece 5, at least the upstream end portion in the fin forming direction D2 of the sub-groove edge portion 4 and the fin 2 adjacent on the upstream side in the tube axis direction D1. If it is the structure provided with the 1st main groove side protrusion piece 5a which protrudes in the main groove 3 between, the 1st main groove side protrusion piece 5a, the 2nd main groove side protrusion piece 5b, the 3rd main groove side protrusion piece 5c In addition to the configuration including all of the fourth main groove side protruding pieces 5d, in addition to the first main groove side protruding pieces 5a, the second main groove side protruding pieces 5b and the third main groove side protruding pieces 5c are provided. Further, it may be configured to include at least one of the fourth main groove side protruding pieces 5d.

  Further, the heat transfer tube manufacturing apparatus 11 is not limited to using the sub-groove forming die 29 as the sub-groove forming pressing tool in the sub-groove processing section 15. For example, a plurality of rolling balls as in the main groove processing section 14 are used. The configuration of the sub-groove forming pressing tool such as 26 or a rolling roller is not particularly limited, but the cross-section of the heat transfer tube 1 can be maintained in a circular shape by processing the sub-groove using the sub-groove forming die 29 described above. preferable.

  Similarly, the main groove processing portion 14 is not limited to using the rolling ball 26, and may be rolled using other configurations such as a main groove forming die and a rolling roller.

  Thus, the present invention is not limited to the above-described embodiments, and can be configured in various embodiments.

DESCRIPTION OF SYMBOLS 1 ... Heat-transfer tube 1a ... Elementary tube 2 ... Fin 3 ... Main groove 4 ... Sub-groove edge part 5 ... Main groove side protrusion piece 6 ... Sub groove structure part 6A ... Base end side sub groove structure part 6B ... Tip side sub groove structure Part 7 ... Sub-groove 7A ... First sub-groove 10 ... Pipe inner surface 11 ... Heat transfer tube manufacturing device 13 ... Reduced diameter portion 14 ... Main groove processed portion 15 ... Sub-groove processed portion 16 ... Drawing device 22 ... Reduced diameter die 23 ... Floating plug 25 ... Main groove forming plug 25a ... Inner fin forming groove 26 ... Rolling ball 28 ... Sub groove forming plug 28a ... Sub groove forming blade 29 ... Sub groove forming die α ... Sub groove angle α ₁ ... Base end side sub groove outer diameter D _{GP ...} inner surface fin-forming groove of the sub-groove forming plugs containing angle alpha _{2 ...} front end side auxiliary groove angle Z 1 _... minor groove machining first region Z 2 _... sub-groove processed second region D _{SP ...} minor groove forming blade Outer diameter of main groove forming plug including H _HGP ... Depth of main groove forming plug Z _SP ... Notch ratio

Claims (9)

On the inner surface of the tube, a spiral fin having a predetermined angle with respect to the tube axis direction is formed, and a main groove is formed between the adjacent fins,
A sub-groove edge that constitutes a peripheral portion of the concave sub-groove formed in the fin;
A heat transfer tube provided with a sub-groove constituting portion constituted by a main groove side projecting piece projecting toward the main groove side on the upstream side in the tube axis direction at least at the upstream end portion in the fin forming direction at the sub groove edge. Because
The projecting direction proximal end side from the inner surface of the tube among the minor groove constituting portions is set as a proximal end side minor groove constituting portion, and the projecting direction distal end side is designated as a distal end side subsidiary groove constituting portion,
The minor groove angle between the proximal-side sub grooves component of the sub-groove angle between the sub-groove arrangement portion facing on both sides of the fin-forming direction in the minor groove, while the base end side auxiliary groove angle alpha ₁ ,
The minor groove angle between the distal-side sub grooves constituting unit, a front end side auxiliary groove angle alpha _2,
The sub-groove component part,
Heat transfer tubes than the proximal-side sub groove angle alpha ₁ was formed in the distal-side sub groove angle alpha ₂ increases shape. _{2. The} heat transfer tube according to claim 1, wherein the base-end side sub-groove angle α ₁ is in a range of 10 ° to 90 °, and the tip-side sub-groove angle α ₂ is in a range of 30 ° to 170 °. The main groove side protruding piece,
3. The heat transfer tube according to claim 1, wherein the heat transfer tube is formed at a projecting angle within a range of 5 ° to 90 ° with respect to the fin from the sub-groove edge in a plan view with respect to the fin. The heat transfer tube according to any one of claims 1 to 3, wherein a ratio of the main groove side protruding piece to a distance between the main grooves is set in a range of 0.1 to 0.9. The minor groove,
The heat transfer tube according to any one of claims 1 to 4, wherein the heat transfer tube is formed with 4 to 60 strips per tube circumference. While the base tube is drawn from the upstream side to the downstream side, the inner surface of the tube is crushed by the main groove forming plug provided with the inner surface fin forming groove on the outer periphery, and the spiral fin of a predetermined angle with respect to the tube axis direction is formed on the inner surface of the tube. Forming a main groove between the adjacent fins by forming, and
By forming the sub-groove in the fin with a sub-groove forming plug provided on the outer periphery with a sub-groove forming blade that intersects the fin at a predetermined crossing angle, a sub-groove edge included in the peripheral portion of the sub-groove And a sub-groove constituting portion composed of a main groove-side protruding piece projecting toward the main groove on the upstream side in the tube axis direction is formed at least on the upstream end in the fin forming direction at the edge of the sub-groove. A heat transfer tube manufacturing method for performing a sub-groove forming step,
The sub-groove forming step includes
Wherein the outer diameter D _SP of the sub-groove formed plugs containing minor groove forming _blade, said main outer diameter of the groove forming plugs D _GP, when the groove depth of the main groove formed plug was H _GP,
(D _GP -2 × H _GP ) <D _SP <D _GP
Using the auxiliary groove forming plug satisfying the range of
Of the sub-groove forming plug and a sub-groove forming pressing tool that is disposed outside the base tube and presses the base tube toward the sub-groove forming plug, the sub-groove that forms the first sub-groove with only the sub-groove forming plug. Forming first step;
After the first step of forming the sub-groove, the first sub-groove is further cut by the sub-groove forming blade by pressing the element tube toward the sub-groove forming plug with the sub-groove forming pressing tool. Performing a secondary groove forming second step to form as a groove,
In the sub-groove forming first step, the first sub-groove is formed on the fin by the sub-groove forming blade that overlaps the fin in the pipe radial direction while pulling out the raw pipe. .
Manufacturing method of heat transfer tube. A notch ratio Z _SP indicating a notch depth of the fin in the first step of forming the sub-groove to cut the fin to form the first sub-groove with respect to the height of the fin,

When a method for producing a heat exchanger tube according to claim 6, wherein the notch ratio Z _SP in the sub groove forming the first step 0.1 or more. Method of manufacturing a heat exchanger tube according to claim 7, wherein 0.6 the notch ratio Z _SP in the minor groove formed first step or less. A drawing means for drawing the base pipe from the upstream side to the downstream side;
An inner surface fin forming groove is provided on the outer periphery, and the inner surface of the tube is crushed to form a spiral fin having a predetermined angle with respect to the tube axis direction on the inner surface of the tube, thereby forming a main groove between the adjacent fins. A main groove forming means provided with a main groove forming plug;
A sub-groove forming plug provided on the outer periphery with a sub-groove forming blade that intersects the fin at a predetermined crossing angle, and a sub-groove forming pressing tool that is provided on the outer side of the raw tube and presses the raw tube toward the sub-groove forming plug. And forming a sub-groove in the fin, so that the sub-groove edge at the peripheral edge of the sub-groove, and at least the upstream end of the fin formation direction at the sub-groove edge, in the tube axis direction A heat transfer tube manufacturing apparatus configured with sub-groove forming means for forming a sub-groove constituting portion provided with a main groove-side protruding piece projecting to the upstream main groove side,
Wherein the minor groove forming plugs, the outer diameter D _SP of the sub-groove formed plugs containing minor groove forming _blade, the main groove forming the outer diameter of the plug D _GP, the groove depth of the main groove forming plugs H _GP When
(D _GP -2 × H _GP ) <D _SP <D _GP
Configured to meet the scope of
The upstream side in the sub-groove forming means is a sub-groove processing first region that forms the first sub-groove only by the sub-groove forming plug out of the sub-groove forming plug and the sub-groove forming pressing tool,
The downstream side of the secondary groove processing first region in the secondary groove forming portion,
The primary tube is pressed to the secondary groove forming plug side by the secondary groove forming pressing tool to further cut the first secondary groove and form a secondary groove processing second region to be cut and formed as the secondary groove,
The minor groove forming plug,
Arranged across the sub-grooving first region and the sub-grooving second region,
The auxiliary groove forming pressing tool,
A heat transfer tube manufacturing apparatus disposed only in the second subgrooving region, out of the first subgroove region and the second subgroove region.

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