JP2000283680A - Pipe with grooved inside face and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe having a grooved inside face and a method of manufacturing of the pipe suitable as a heat transfer pipe of a condenser and an evaporator capable of attaining a high condensing performance and a high evaporating performance even in a zone having a less flow rate of refrigerant. SOLUTION: Helically grooved belts 1 having a helical groove in an inside surface of a metallic pipe or an alloy pipe and cross-grooved belts 2 having a group of cross-grooves formed by crossing a plurality of grooves at the inside surface of the metallic pipe or the alloy pipe are arranged in regions that are different from each other. One or a plurality of the helically-grooved belts 1 and the cross-grooved belts 2 are arranged alternately in a circumferential direction of the metallic pipe or the alloy pipe. When the width of the helically grooved belts 1 in the circumferentical direction of the pipe is set as W1 and the width of the cross-grooved belts 2 is set as W2, the ratio W1/W2 of W1 and W2 is 1.1 to 3.0. In addition, it is also possible to set this ratio of W1/W2 to 0.3 to 0.9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner grooved tube suitable for a heat exchanger for a condenser or an evaporator used in a heat exchanger of a room air conditioner or the like, and a method for manufacturing the same. The present invention relates to an inner grooved tube which exhibits high condensation performance and high evaporation performance, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, in a heat exchanger such as an air conditioner, an internally grooved tube having a plurality of spiral grooves on the inner surface of the tube has been used as a heat transfer tube in order to enhance heat exchange performance.

[0003] The heat exchange of an air conditioner or the like utilizes latent heat when evaporating a refrigerant liquid or condensing refrigerant gas. To improve the evaporation performance, the refrigerant liquid is spread over the entire heat transfer tube and transferred. A structure in which evaporation occurs on the entire hot surface is required. On the other hand, in order to improve the condensing performance, a structure in which the refrigerant liquid condensed on the heat transfer surface can be easily removed and the liquid is easily collected in one place so that the heat transfer surface is not covered again by the removed liquid. preferable.

Recently, in air conditioners and the like, it is required to improve heat transfer performance (evaporation performance and condensation performance) in order to save energy. A heat transfer tube that exhibits high heat transfer performance even in an area with a small amount of heat is indispensable.

Conventionally, the following heat transfer tubes have been proposed as inner grooved tubes in which the inner surface of the tube is processed to improve the heat transfer performance.

In the heat transfer tube described in Japanese Patent Application Laid-Open No. 4-158193, a plurality of types of spiral grooves are provided, and these spiral grooves are formed between adjacent spiral grooves in the direction of the tube axis. At least one or more of the pitch, the groove size, the groove shape, and the torsion angle of the groove group with respect to the pipe axis direction are different from each other.

In the heat transfer tube described in JP-A-8-121984, a plurality of continuous fins are formed so as not to cross each other in the tube axis direction, and the continuous fins are adjacent to the continuous fins and intersect with the continuous fins. Discontinuous or sawtooth-shaped discontinuous fins along the longitudinal direction and grooves formed between the discontinuous fins and the continuous fins are provided so as to prevent the fins from being disturbed.

Further, in the heat transfer tube having an inner cross groove described in Japanese Patent Application Laid-Open No. 8-178574, a main groove is formed on the inner surface of the tube with an inclination of 7 ° to 25 ° with respect to the tube axis, and a sub groove is formed. The flow of the refrigerant is guided in the direction of the sub-groove by being provided parallel to the pipe axis or by providing burrs on the three-dimensional protrusions left between the main groove and the sub-groove.

Furthermore, in the heat transfer tube with an inner surface groove described in Japanese Patent Application Laid-Open No. Hei 10-206060, the first and second heat transfer tubes having the same groove pitch in the circumferential direction of the tube and different twist angles and twist directions with respect to the tube axial direction. A second groove group is provided, and the first and second groove processing regions in which the first and second groove groups are formed are arranged in a plurality of sets in circumferential directions with different widths. , A straight groove region extending in the pipe axis direction is arranged.

[0010]

However, the above-mentioned conventional heat transfer tubes have the following problems. First, in the heat transfer tube described in Japanese Patent Application Laid-Open No. 4-158193, the flow of the refrigerant liquid is not hindered, but the pressure loss cannot be sufficiently reduced at the time of evaporation. Since the liquid discharge performance is not sufficient, the contact between the heat transfer surface and the refrigerant gas is reduced, and the condensation performance is reduced. In addition, if spiral grooves having the same twist angle with respect to the tube axis direction are provided on the entire inner surface of the tube, condensate tends to spread over the entire heat transfer surface during condensation, and the heat transfer surface is covered with the condensate. However, there is a problem that the condensation performance is reduced.

Further, in the heat transfer tubes described in JP-A-8-121984 and JP-A-8-178574, the heat transfer surface is designed on the basis of the continuous groove.
When used as a condenser, the refrigerant gas condensate is likely to produce a swirling flow along the groove. As a result, it becomes difficult to secure a dry heat transfer surface necessary for the condensation, and the condensation performance is reduced. Therefore, there is a disadvantage that it is not preferable for a heat pump type air conditioner that requires evaporation performance and condensation performance.

Further, in the heat transfer tube described in Japanese Patent Application Laid-Open No. H10-206060, when the flow rate of the refrigerant is small, the swirling flow of the refrigerant is obstructed by the grooves in the opposite direction, and the evaporation performance is reduced. There is a point.

As described above, each of the conventional techniques has advantages and disadvantages, and there is a problem in that it is not possible to ensure excellent performance in both the evaporation performance and the condensation performance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and can provide high condensation performance and high evaporation performance even in a region where the flow rate of refrigerant is small. It is an object of the present invention to provide an inner grooved pipe suitable as the above and a method for manufacturing the same.

[0015]

According to the present invention, there is provided an inner grooved pipe having a spiral groove formed on an inner surface of a metal or alloy pipe and a spiral groove formed on the inner surface of the metal or alloy pipe. A cross-groove processing band in which a cross-groove group formed by intersecting a plurality of grooves arranged in a region different from the processing band, and wherein the spiral groove processing band and the cross-groove processing band are the metal or alloy. One or more are alternately arranged in the inner peripheral direction of the pipe, and the processing width of the spiral groove processing band in the inner peripheral direction is W ₁ ,
When the processing width of the intersecting grooved zone was W _2, W ₁ and W ₂
The ratio W ₁ / W ₂ is 0.3 to 0.9 or 1.1 to 3.
It is characterized by being 0.

In the present invention, when the inner grooved tube of the present invention is used as an evaporator, when a refrigerant liquid is supplied into the inner grooved tube, a plurality of groove groups are mutually formed in the cross groove processing zone. Since the intersecting intersecting groove group is formed, the intersecting groove portion where the respective grooves intersect becomes a boiling nucleus, and the evaporation of the refrigerant liquid is promoted, so that the evaporation performance can be improved.

On the other hand, when the inner grooved tube is used as a condenser, when a refrigerant gas is supplied into the inner grooved tube, the refrigerant gas comes into contact with the heat transfer surface and is cooled and condensed. This condensed refrigerant liquid (refrigerant gas condensate) tends to generate a swirl flow along the grooves formed in the region with a wide processing width, but the refrigerant gas condensate in the early stage of liquefaction has a small inertia of the flow. ,
The flow of the swirling flow is suppressed by a groove group formed in a region having a narrow processing width and inclined in a direction opposite to the groove group. For this reason,
The refrigerant gas condensate tends to collect at the lower part of the inner grooved pipe due to gravity, so that the entire heat transfer surface is not covered with the refrigerant gas condensate, and the heat transfer surface is always in the upper part of the inner grooved pipe. To maintain continuous condensation in contact with the refrigerant gas,
High condensation performance can be obtained.

When W ₁ / W ₂ is less than 0.3, the flow of the swirling flow of the refrigerant is promoted, so that the evaporation performance is improved. When the heat transfer surface is covered with the refrigerant gas, the contact between the heat transfer surface and the refrigerant gas is hindered. On the other hand, when W ₁ / W ₂ is more than 0.9 and not more than 1.0, the condensation performance is improved, but the evaporation performance due to the suppression of the swirling flow of the refrigerant by the spiral grooves in the spiral groove processing zone. Is reduced.

Further, when W ₁ / W ₂ is less than 1.1, the condensation performance is improved, but the effect of suppressing the swirling flow of the refrigerant due to the cross groove portion of the narrow cross groove processing zone is increased, and the evaporation performance is reduced. Occurs. On the other hand, when W ₁ / W ₂ exceeds 3.0,
Although the swirling flow of the refrigerant is promoted and the evaporation performance is improved,
Condensate liquefied during condensation tends to spread over the entire heat transfer surface of the inner grooved tube, and the condensate covers the heat transfer surface of the inner grooved tube, preventing contact between the refrigerant gas and the heat transfer surface and condensing performance. descend. Therefore, W ₁ / W _{2 is set} to 0.3 to 0.9 or W ₁ / W ₂
Is set to 1.1 to 3.0, high performance can be obtained in both the evaporation performance and the condensation performance.

Further, among one groove group and another groove group that intersect the cross groove group formed in the cross groove processing zone, the one groove group is a pipe shaft of the metal or alloy pipe. Is preferably formed in a direction opposite to the spiral groove, and the groove bottom width of the one groove group is wider than the groove bottom width of the other groove group. In this case, the one groove group may be formed such that the groove bottom is continuous in the longitudinal direction, and the other groove group may be formed such that the groove bottom is discontinuous in the longitudinal direction. As described above, by making the continuity of one groove group stronger than that of the other groove groups, the refrigerant liquid generates a swirling flow along the one groove group having a stronger continuity than the other groove groups, and the inside of the pipe is formed. Spread over the entire surface. For this reason, the evaporation performance of the inner grooved tube can be further improved.

[0021] The method for manufacturing an inner grooved pipe according to the present invention is characterized in that the surface of a band-shaped strip made of a metal or an alloy is rolled,
The cross groove processing band and the spiral groove processing band are formed under the conditions according to claim 1, and the strip material is rounded with the surface on which the cross groove processing band and the spiral groove processing band are formed inside. It is characterized in that the butted ends are welded.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an inner grooved pipe according to an embodiment of the present invention and a method for manufacturing the same will be specifically described with reference to the accompanying drawings. FIG. 1 is a schematic view showing a state in which the inner surface of an inner grooved tube according to a first embodiment of the present invention is developed in a circumferential direction of the tube.

In the inner grooved pipe of this embodiment, metal or metal is used.
Forms a spiral groove group 6 continuous in the pipe axis direction on the inner surface of the alloy pipe
Spiral groove processing zone 1 is arranged. This spiral groove processing
A plurality of grooves adjacent to the band 1 and formed of grooves extending in the pipe axis direction
Intersecting groove processing zone 2 forming an intersecting groove group which intersected group 3
Are located. That is, spiral groove processing in metal or alloy pipe
Three bands 1 and three cross-grooved bands 2 are alternately arranged.
You. The pipe circumference of the spiral groove processing zone 1 and the cross groove processing zone 2
The processing width in the direction is W₁, W_TwoAnd W ₁Is W_TwoYo
Bigger.

An inner grooved pipe having such a groove shape is as follows.
A As shown in FIG. 1 one surface of the strip-shaped elongated member made of metal or alloy, processed width processing width and helical grooves band 1 of W ₁ is W ₂
The groove shape is transferred by rolling so that the cross groove processing bands 2 are alternately arranged, and the groove is curved into a tubular shape with the groove forming surface of the material inward, and the material is abutted while being rounded in the pipe circumferential direction. It can be manufactured by welding the ends.

Next, the operation of the inner grooved pipe having the above-described structure will be described. When this inner grooved tube is used as an evaporator, first, a refrigerant liquid is supplied into the inner grooved tube. The different grooved zones of the pipe circumferential direction of the processing width continuous with the tube axis direction to the tube with the inner surface groove is provided, placing grooves each different shapes, refrigerant liquid wide working width of the pipe circumferential direction and W ₁ helix The flow along the groove of the grooved band 1 is likely to occur. Therefore, the pipe circumferential direction of the processing width W ₁ and a broad helical grooving band 1
By forming a spiral groove on the inner surface, a swirling flow of the refrigerant is generated in the inner grooved pipe. Therefore, the refrigerant liquid spreads over the entire inner grooved pipe, and high evaporation performance can be obtained.

Further, by forming a groove group 3 having a plurality of grooves intersecting in the cross groove processing band 2 having a processing width in the pipe circumferential direction narrower than W ₂ , the cross groove portions 4 of the respective grooves are formed. It becomes a boiling nucleus, and evaporation is promoted, so that the evaporation performance of the inner grooved tube can be enhanced.

By the way, when the flow rate of the refrigerant is small, the flow velocity of the refrigerant is low, so that the swirling flow of the refrigerant liquid is unlikely to occur.
Since the crossing grooves 4 of the grooves serve as boiling nuclei to promote evaporation of the refrigerant liquid, high evaporation performance can be ensured even in a region where the refrigerant flow rate is small.

On the other hand, when the inner grooved tube is used as a condenser, the refrigerant gas is supplied to the inner grooved tube. This refrigerant gas contacts the heat transfer surface and is cooled and condensed (liquefied). The condensed refrigerant liquid (refrigerant gas condensate) is processing width of the tube circumferential direction along the groove of W ₁ and a broad helical grooving band 1,
To about to fail the swirl flow, but this time, the refrigerant liquid for the inertia of the flow is small, the processing width is narrow and W ₂ intersect groove processing zone 2
The swirling flow is suppressed by the intersecting groove portion 4 formed in the ridge. For this reason, the condensed refrigerant liquid tends to condense on the lower surface of the heat transfer tube due to gravity, and the entire heat transfer surface is not covered with the condensed refrigerant liquid. Maintain continuous condensation on contact. For this reason, high condensation performance can be obtained.

When W ₁ / W ₂ is less than 1.1 with respect to each processing width of the groove forming area, the condensing performance is improved, but the refrigerant is swirled by the cross grooves 4 of the narrow cross groove processing zone 2. The effect of suppressing the flow is increased, and the evaporation performance is reduced. On the other hand, if W ₁ / W ₂ exceeds 3.0, the swirling flow of the refrigerant is promoted and the evaporation performance is improved, but the condensed liquid liquefied at the time of condensation tends to spread over the entire heat transfer surface of the inner grooved tube. In addition, the condensed liquid covers the heat transfer surface of the inner grooved tube, so that contact between the refrigerant gas and the heat transfer surface is hindered, and condensing performance is reduced. Therefore, W ₁ / W ₂ is set to 1.1 to 3.0.

In this embodiment, the cross groove machining zone 2 is formed by forming a cross groove group in which a plurality of groove groups 3 formed of grooves continuous in the pipe axis direction are intersected. However, the present invention is not limited to this. Among the cross groove groups formed in the cross groove processing band 2, one groove group 3 has a twist with respect to the pipe axis, and this twist is formed in the spiral groove processing band 1. The spiral groove may be formed in the opposite direction. Also, this one groove group 3 is formed such that the groove bottom width of the groove group 3 in the tube axis cross section is wider than the other groove groups 5 in comparison with the other groove groups 5 of the cross groove processing band 2. May be. This makes it easier for the refrigerant and the like to flow.

In this embodiment, three spiral groove machining zones 1 and three cross groove machining zones 2 are alternately arranged. However, the present invention is not particularly limited to this.
For the respective pieces of processing width of the spiral grooving band 1 and crossing grooves band _2, W ₁ / W 2 is alternately to one or more arranged on the inner surface of the metal or alloy tube within the 1.1 to 3.0 be able to.

Next, a second embodiment of the present invention will be described. FIG. 2 is a schematic view showing a state in which the inner surface of an inner grooved pipe according to a second embodiment of the present invention is developed in the circumferential direction of the pipe, and FIG.
FIG. 3 is a perspective view showing a groove shape on the surface of the cross groove processing band 2 in FIG. 2. In FIG. 2, the same components as those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 2, in the inner grooved tube of the present embodiment, the cross grooved band 2 and the spiral grooved band 1 are alternately formed on the inner surface of the metal or alloy tube in the circumferential direction of the tube. They are arranged three by three. The processing width W ₂ of the cross groove processing band 2 in the pipe circumferential direction is larger than the processing width W ₁ of the spiral groove processing band 1 in the pipe circumferential direction.

In the spiral groove machining zone 1, a spiral groove group 6 composed of a plurality of spiral grooves extending at a predetermined twist angle with respect to the tube axis direction is formed. On the other hand, in the intersecting groove processing zone 2, a plurality of groove groups formed of spiral grooves are formed so that the twist angles with respect to the tube axis direction are different from each other, and cross each other. Among the plurality of groove groups in the cross groove processing band 2, the groove group 3 having strong groove continuity has a twist direction with respect to the tube axis direction, which is the twist direction of the spiral groove group 6 formed in the spiral groove processing band 1. Are formed in the opposite direction.

As shown in FIG. 3, in the intersecting groove processing zone 2, groove groups 3 and 5 composed of a plurality of spirally extending grooves are formed so as to intersect with each other. In the strong groove group 3, the groove bottom surface 11 is continuous in the longitudinal direction of the groove, and in the groove group 5 with weak continuity, the groove bottom surface 12 is discontinuous in the longitudinal direction of the groove. Groove group 3 with strong continuity
The width D ₁ of the groove bottom is wider than the width D ₂ of the groove bottom of the groove group 5 having weak continuity (D ₁ > D ₂ ). However, the refrigerant and the like are easier to flow than in the groove group 5 where the continuity is weak.

An inner grooved tube having such a groove shape is as follows.
On one surface of a strip-shaped elongated member made of a metal or alloy, as shown in FIG. 2, the processing width processing width cross groove processing zone 2 of W ₂ is W ₁
The groove shape is transferred by rolling so that the spiral groove processing strips 1 are alternately arranged, and the groove is curved into a tubular shape with the groove forming surface of the material inside, and the material is joined while being rounded in the pipe circumferential direction. It can be manufactured by welding the ends.

In the inner grooved pipe of the present embodiment having the above-described structure, when used as an evaporator, first,
The coolant liquid is supplied into the inner grooved pipe. Cross groove machining zone 2 in which grooves having mutually different shapes are formed on the inner surface of the inner grooved pipe.
And the spiral groove processing bands 1 are alternately arranged in the circumferential direction of the pipe, and since the width of the cross groove processing band 2 is wider than the width of the spiral groove processing band 1, the flow of the refrigerant liquid is caused by the cross groove processing band 2. Strongly influenced by

At this time, one groove group 3 of the plurality of groove groups constituting the cross groove machining zone 2 is formed with a twist with respect to the tube axis and is formed with strong continuity. Therefore, the coolant liquid generates a swirling flow along the groove group 3 and spreads over the entire inner surface of the pipe. For this reason, the evaporation performance of the inner grooved tube is improved.

Further, in the cross groove processing zone 2, since a plurality of cross groove groups intersect with each other, an intersecting groove portion 4 where each groove intersects serves as a boiling nucleus, thereby promoting the evaporation of the refrigerant liquid. Therefore, the evaporation performance of the inner surface grooved tube can be further improved.

By the way, when the flow rate of the refrigerant is small, the flow velocity of the refrigerant is slow, so that the swirling flow of the refrigerant liquid is hardly generated.
Since the crossing grooves 4 of the grooves serve as boiling nuclei to promote evaporation of the refrigerant liquid, high evaporation performance can be ensured even in a region where the refrigerant flow rate is small.

On the other hand, when the inner grooved tube is used as a condenser, the refrigerant gas is supplied into the inner grooved tube. This refrigerant gas comes into contact with the heat transfer surface and is cooled and condensed (liquefied). The condensed refrigerant liquid (refrigerant gas condensate) tends to generate a swirling flow along the groove group 3 formed in the cross groove machining zone 2, and at this time, the refrigerant gas condensate has a small inertia of the flow. Therefore, the flow of the swirling flow is suppressed by the spiral groove group 6 whose twisting direction is opposite to that of the groove group 3 formed in the spiral groove processing band 1 and formed in the cross groove processing band 2.

Therefore, the refrigerant gas condensate tends to collect on the lower surface side of the inner grooved tube due to gravity, so that the entire heat transfer surface is not covered with the refrigerant gas condensate, and the upper surface of the inner grooved tube is not covered. On the side, the heat transfer surface is always in contact with the refrigerant gas to maintain continuous condensation. For this reason, high condensation performance can be obtained.

Incidentally, the ratio between the width W ₂ and the width W ₁ of the spiral groove processing zone 1 of the cross groove processing zone 2, i.e., when W ₁ / W ₂ is in exceed 0.9 1.0, condensed Although the performance is improved, the evaporation performance is reduced due to the suppression of the swirling flow of the refrigerant by the spiral groove group 6 of the spiral groove processing zone 1.

On the other hand, if W ₁ / W ₂ is less than 0.3, the flow of the swirling flow of the refrigerant is promoted, so that the evaporation performance is improved. The heat transfer surface covers the heat transfer surface, and the contact between the heat transfer surface and the refrigerant gas is hindered.

Therefore, W ₁ / W ₂ is 0.3 to 0.9 in order to obtain high performance in both evaporation performance and condensation performance.

Further, when two types of groove groups are formed which are twisted in opposite directions to the pipe axis and are formed with a wide groove bottom width,
Since the pressure loss increases, it is preferable to make the respective twist angles different.

Further, in this embodiment, three cross groove processing bands 2 and three spiral groove processing bands 1 are alternately arranged. However, the present invention is not particularly limited to this.
Regarding the respective processing widths of the cross groove processing band 2 and the spiral groove processing band 1, one or more are arranged alternately on the inner surface of the metal or alloy pipe within a range of W ₁ / W ₂ of 0.3 to 0.9. be able to.

[0048]

EXAMPLES Hereinafter, the results of manufacturing an inner grooved pipe according to an embodiment of the present invention and comparing the characteristics of the pipe with the inner grooved pipe of a comparative example will be specifically described.

As a material for the inner grooved pipe of the examples and comparative examples, a phosphorous deoxidized copper (JIS H3) having a thickness of 0.45 mm was used.
100 C1220) A strip-shaped strip material slit to a predetermined width by a coil was used. The grooving process on this strip is performed by arranging a smooth roll on the lower side and passing the strip through a rolling mill having a groove forming roll of a predetermined shape on the upper side, and transferring the uneven shape of the upper roll to the strip. Was performed. In order to form the spiral groove and the cross groove of the present invention on the same strip, a tandem type rolling mill having two rolling mills in one line may be used, or a rolling having only one set of rolls. In the case of using the apparatus, for example, a spiral groove is first formed by rolling and rolled up, and then a second rolling performed by rearranging the upper roll forms a spiral groove in a direction opposite to that of the first time. Intersecting grooves may be formed at positions. In this example and the comparative example, a grooved strip was manufactured by using a tandem rolling mill in which two rolling mills were continuously arranged.

As described above, a tandem rolling mill in which two rolling mills are continuously arranged is used, and the groove depth is 0.2 mm and the groove pitch in the circumferential direction of the pipe is 0.41 mm in the first rolling mill. A primary groove group having a twist angle of 15 ° in the right-hand screw direction with respect to the pipe axis was roll-formed on the entire surface on one side except for 1 mm at both ends of the strip. The fins (protrusions) had an apex angle of 25 ° and a groove bottom thickness (minimum thickness) of 0.25 mm.

The strip which has been groove-rolled by the first-stage rolling mill is subsequently led to the second-stage rolling mill, where the groove depth is 0.2 mm.
A secondary groove group having a circumferential groove pitch of 0.41 mm in the circumferential direction of the pipe and a twist angle of 30 ° in the left-hand thread direction with respect to the pipe axis (having a different twist angle and twist direction from the primary groove group) At three places in the thickness direction (corresponding to the circumferential direction of the tube), rolling was performed with a predetermined working width at predetermined intervals. It should be noted that, in the portion that is not subjected to the reduction in the secondary rolling, the groove in the primary rolling remains as it is. That is, a grooved copper plate in which spiral grooved bands formed by primary rolling and cross grooved bands formed by secondary rolling are alternately arranged in the plate width direction is obtained. In the second-stage rolling mill, the ratio between the processing width of the spiral groove processing band and the processing width of the cross groove processing band was changed by incorporating a groove forming upper roll having a different width.

With the grooved surface of the grooved material turned inward as described above, the width of the grooved material is rounded, the ends of the width of the plate are abutted, and high-frequency welding is performed. An inner grooved tube having a diameter of 7.0 mm was formed.

The thus formed inner grooved pipe is connected to a double-pipe heat exchanger having a length of 3000 mm (hereinafter referred to as an outer pipe).
The refrigerant (R-410A) is placed inside the inner grooved pipe.
Was supplied, and water was supplied to the annular portion between the inner grooved tube and the outer tube to perform heat exchange, and the heat transfer performance was measured.

As a standard material for comparing the heat transfer performance with that of the present embodiment, an internally grooved pipe having an outer diameter of 7.0 mm (groove depth: 0.2 mm, Circumferential groove pitch of pipe: 0.41 mm, twist angle to pipe axis: 18 ° (right-hand screw direction), fin apex angle: 20 °, groove bottom wall thickness: 0.25 mm), and its heat transfer performance Was measured, and the performance of the internally grooved tubes of the examples and comparative examples was expressed as a ratio to the heat transfer performance of this standard material.

FIG. 4 shows the heat transfer performance ratio on the vertical axis, the processing width (W ₁ ) of the cross groove processing band in which the cross groove group is formed on the horizontal axis, and the processing of the spiral groove processing band in which the spiral groove group is formed. FIG. 4 is a graph showing the relationship between the ratio (W ₁ / W ₂ ) and the heat transfer performance ratio by taking the ratio (W ₁ / W ₂ ) to the width (W ₂ ). In the figure, ▲ indicates the evaporation performance ratio, and ● indicates the condensation performance ratio.

The ratio (evaporation performance ratio and condensation performance ratio) between the heat transfer performance of the inner grooved tube of this embodiment and the heat transfer performance of the inner grooved tube of the standard material when the refrigerant flow rate is 20 kg / hour is as follows. It is shown in Table 1 and FIG.

[0057]

[Table 1]

As shown in Table 1 and FIG. 4, W ₁ / W ₂ is 1
, The heat transfer performance was equivalent to that of the standard material. W ₁
As / W ₂ becomes smaller or larger than 1, the heat transfer performance (evaporation performance and condensation performance) sharply increases, and W ₁ / W ₂ becomes 0.3 to 0.9 and W ₁ / W _2. W ₂ is 1.1
In the range from 3.0 to 3.0, the heat transfer performance was significantly improved by 20% or more compared to the standard material. In the region of less than W ₁ / W ₂ is 0.3, the condensation performance is lowered, W ₁
In the region where / W ₂ exceeds 3.0, the evaporation performance was reduced. The evaporation performance is particularly excellent in the region where W ₁ / W ₂ is 0.3 to 0.9, while the condensation performance is particularly excellent in the region where W ₁ / W ₂ is 1.1 to 3.0. It was excellent.

[0059]

As described above in detail, according to the present invention, W
_{Since 1} / W ₂ is 0.3 to 0.9 or 1.1 to 3.0, both the evaporation performance and the condensation performance are excellent, and by using the inner grooved tube of the present invention, Even when the flow rate of the refrigerant is small, the performance of the heat exchanger is extremely excellent, and the energy saving effect of an air conditioner or the like is significantly improved. In addition, a heat exchanger with an excellent evaporation performance ratio of W ₁ / W ₂ of 0.3 to 0.9 is used for the heat exchanger in which the indoor cooling performance is particularly important, and a heat exchanger in which the indoor heating performance is particularly important. By using a heat transfer tube having an excellent condensation performance ratio of W ₁ / W ₂ of 1.1 to 3.0 as the exchanger, the heat exchanger performance can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state in which an inner surface of an inner grooved tube according to a first embodiment of the present invention is developed in a circumferential direction of the tube.

FIG. 2 is a schematic view showing a state in which the inner surface of an inner grooved pipe according to a second embodiment of the present invention is developed in a circumferential direction of the pipe.

FIG. 3 is a perspective view showing a groove shape on the surface of the cross groove processing band of FIG. 2;

FIG. 4 shows the heat transfer performance ratio on the vertical axis, the processing width (W ₁ ) of the cross groove processing band in which the cross groove group is formed on the horizontal axis, and the processing width of the spiral groove processing band in which the spiral groove group is formed ( Ratio to W ₂ ) (W ₁ / W ₂ )
FIG. 3 is a graph showing the relationship between the ratio (W ₁ / W ₂ ) and the heat transfer performance ratio.

[Explanation of symbols]

 1; spiral groove processing band 2: cross groove processing band 3, 5; groove group 4: cross groove portion 6; spiral groove group 11, 12; groove bottom surface

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyonori Koseki 65, Hirasawa, Hadano City, Kanagawa Prefecture Inside the Hadano Plant, Kobe Steel Co., Ltd. (72) Inventor Nobuaki Hinako 65, Hirasawa, Hadano City, Kanagawa Prefecture Hadano Plant, Kobe Steel Corporation F-term (reference) 4E028 EA07

Claims (4)

[Claims] 1. A helical groove processing band in which a helical groove is formed on an inner surface of a metal or alloy pipe, and a plurality of grooves arranged in a different region from the helical groove processing band on the inner surface of the metal or alloy tube. And a plurality of crossed groove processing bands in which a set of crossed groove groups are formed, wherein one or a plurality of the spiral groove processing bands and the cross groove processing bands are alternately arranged in the inner circumferential direction of the metal or alloy pipe. together, the processing width of the helical groove machining zone in the inner peripheral direction is W _1, the intersecting when the working width of the grooved zone and the W _2, W ₁ and W: W and W _{2 1} / W ₂ is 0 0.3 to 0.9 or 1.1 to 3.0. 2. One of a group of grooves forming a group of cross grooves formed in the cross groove processing zone and another group of grooves intersecting with the group of grooves, the one group of grooves is a tube axis of the metal or alloy pipe. The twist direction with respect to is formed in the opposite direction to the spiral groove, and the groove bottom width of the one groove group is formed wider than the groove bottom width of the other groove group. 2. The inner grooved pipe according to 1. 3. The groove group according to claim 1, wherein the bottom of the groove is formed continuously in the longitudinal direction, and the bottom of the other groove is formed intermittently in the longitudinal direction. The inner grooved pipe according to claim 2. 4. The method for producing an inner grooved pipe according to claim 1, wherein the cross-grooved band and the cross-grooved band are formed by rolling on the surface of a strip-shaped member made of a metal or an alloy. An inner grooved pipe, wherein a spiral grooved band is formed, and a butt end thereof is welded while rolling the strip with the surface on which the cross grooved band and the spiral grooved band are formed inside. Manufacturing method.