JP2000274983A - Inner surface grooved pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inner surface grooved pipe that is used as a condenser such as a room air conditioner, and has improved condensation performance. SOLUTION: This inner surface grooved pipe is equipped with a first groove machining band 1 where a first groove 2 is formed on the inner surface of a metal or alloy pipe, and a second groove machining band 3 where a second groove 4 that has the same pitch in the pipe circumference direction of the metal or alloy pipe as the first groove 2 and has different helix angle and direction at a region that is different from the first groove machining band 1 on the inner surface of the metal or alloy pipe. In this case, the machining width of the first groove machining band 1 is different from that of the second one 3, one or a plurality of bands is alternately arranged in the circumferential direction of the metal or alloy pipe, at the same time, in the first and second groove machining bands 1 and 3, the helix angle of the groove with wider machining width is set to 45-85 deg., and that of the groove with narrower machining width is set to 8-45 deg..

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 used for a heat exchanger, and more particularly to an inner grooved tube having excellent condensation performance used as a condenser for a room air conditioner or the like.

[0002]

2. Description of the Related Art In Japan, about 80% of air conditioners and the like are of a heat pump type that is used for both cooling and heating.
In the United States and other overseas countries, 40 to 60% of models are exclusively used for cooling. This cooling only model is operated indoors as an evaporator and outdoors as a condenser, and it is necessary to improve the performance of the condenser in order to save energy and improve performance.

In order to improve the performance of a heat exchanger such as an air conditioner, an inner spiral grooved pipe having an inner spiral groove is widely used. Recently, various types of heat transfer tubes processed inside the tubes have been proposed as high performance heat transfer tubes in order to enhance the heat transfer performance (Japanese Patent Laid-Open No. 4-158193).
JP-A-8-121984, JP-A-8-11984
78574 and JP-A-10-206060).

[0004] Among these conventional high-performance heat transfer tubes, in the heat transfer tube described in Japanese Patent Application Laid-Open No. 4-158193, several types of irregularities are formed on the inner surface of the tube with a predetermined width in the tube axis direction. These uneven groups are parallel and alternately located ridges and grooves, and one uneven group and the adjacent uneven group are adjacent to the uneven group, and each element of the groove pitch, the groove dimension, and the lead angle of the groove with respect to the pipe axis. Any one or more of the elements is different. By providing three or more of these irregularities, high heat transfer performance is obtained. This prior art includes:
It describes the effect of increasing the heat transfer performance by disrupting the flow of the refrigerant in the pipe.

In the heat transfer tube described in JP-A-8-121984, a plurality of continuous fins formed so as not to intersect each other in the tube axis direction, and a continuous fin adjacent to the continuous fin. It has discontinuous fins formed discontinuously or in a sawtooth shape along the longitudinal direction so as not to intersect, and grooves formed respectively between the discontinuous fins and the continuous fins.

Further, in Japanese Patent Application Laid-Open No. Hei 8-178574, in a tube with a spiral groove formed on the inner surface, a main groove is formed at 7 ° to 25 ° with respect to the tube axis, and a sub groove is formed. It is configured to be provided in parallel with the tube axis. The heat transfer tube has a main groove formed at 7 ° to 25 ° with respect to the tube axis, and a sub-groove is provided so as to intersect with the main groove. In this configuration, a convex deformed portion is formed when processing the three-dimensional projection left when processing the main groove.

Furthermore, the heat transfer tube described in Japanese Patent Application Laid-Open No. H10-206060 has a configuration in which a plurality of groove groups having different twist directions and twist angles with respect to the tube axis are provided with different processing widths in the circumferential direction of the tube. .

[0008]

However, the above-mentioned high-performance heat transfer tubes (JP-A-4-158193, JP-A-8-121984, JP-A-8-178574, JP-A-10-206060, etc.) ) Is intended for air conditioners and the like that can be used for both cooling and heating, and is provided with a function of improving the performance of both evaporation and condensation. When used as an evaporator and when used as a condenser, for example, a structure that spreads the refrigerant liquid over the entire heat transfer surface is required to improve the evaporation performance, whereas a heat transfer surface is required to improve the condensation performance. The difference is that a structure for collecting the refrigerant liquid in one place is required so that the adhered refrigerant condensate can be easily removed and the heat transfer surface is not covered again by the condensed liquid. That is,
The functions required for the condenser are different.

On the other hand, in the case of the heat transfer tube described in Japanese Patent Application Laid-Open No. 4-158193, when spiral grooves having the same angle are arranged, the refrigerant liquid tends to spread, and the condensation performance is reduced. On the other hand, when the spiral groove having the opposite angle is simply provided, there is a problem that the flow of the refrigerant liquid is obstructed and the pressure loss increases.

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 a continuous groove, and when used as a condenser. In the method, the condensed liquid tends to generate a swirling flow along the groove. As a result, there is a problem that it is difficult to secure a dry heat transfer surface required for the condensation, and the condensation performance is reduced. In Japanese Patent Application Laid-Open No. 8-178574, in the case of an intersecting groove structure, a warp or the like during processing is likely to be generated in the vicinity of a groove intersection, and this warp or the like hinders the separation of the condensate and lowers the performance. There is a point.

Further, in the heat transfer tube described in Japanese Patent Application Laid-Open No. H10-206060, there is a problem that the swirling flow of the condensed liquid is likely to occur under the condition that the refrigerant flow rate is large, and the performance under high load operation is deteriorated. is there.

That is, each of the conventional techniques has advantages and disadvantages, and in particular, there is a problem in improving the condensation performance.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an inner grooved pipe having excellent condensation performance used as a condenser for a room air conditioner or the like.

[0014]

According to the present invention, there is provided a tube with an inner surface having a first groove formed on an inner surface of a metal or alloy tube.
And the pitch of the first groove and the metal or alloy pipe in the pipe circumferential direction are the same in a region different from the first groove processing zone on the inner surface of the metal or alloy pipe, and the torsion angle and A second grooved band in which a second groove having a different twisting direction is formed, wherein the first grooved band and the second grooved band have different processing widths to form the metal or One or more are alternately arranged in the circumferential direction of the alloy pipe, and among the first and second grooved bands, the torsion angle of the groove having the larger processing width is 45 to 85 °, and the processing width is The twist angle of the narrow groove is 8 to 45 °.

In this case, the first and second grooved bands are
Of these, the processing width of the wider groove processing zone is W₁age,
The processing width of the narrower groove processing band is W_TwoWhen
Said W ₁And the W_TwoAnd the ratio W₁/ W_TwoIs from 1.1 to 3.0
Preferably, there is.

It is preferable that a smooth region is formed between the first grooved band and the second grooved band.

The inner grooved pipe is formed by rolling the first grooved band and the second grooved band on the surface of a plate-shaped strip made of metal or alloy by rolling. Can be formed by welding while rolling in the circumferential direction.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing the inner surface of a tube with an inner groove developed according to an embodiment of the present invention.

In this embodiment, a plurality of first grooved bands 1 and a plurality of second grooved bands 3 are formed alternately. A smooth region 5 is formed between the first grooved band 1 and the second grooved band 3.

In the first grooved band 1, a first groove 2 extending in a direction inclined with respect to the tube axis direction has a pitch p in the tube axis direction.
Are formed. The second grooved band 3 has a second groove 4 formed at an angle equal to the first groove 2 with respect to the tube axis direction and inclined in a direction opposite to the first groove 2 in the tube axis direction. Groove 2
Are formed at the same pitch p. Nothing is formed in the smooth region 5, and the first grooved band 1 and the second grooved band 3 are separated so that they are not arranged continuously. The processing width of the first grooved band 1 is W ₁ , the processing width of the second grooved band 3 is W ₂ , and the processing width of the smooth region is W ₃ .

Next, the operation of the inner grooved pipe configured as described above will be described. When this inner grooved tube is used as a condenser, refrigerant gas is supplied into the inner grooved tube. The refrigerant gas contacts the heat transfer surface, is cooled and liquefied, and is discharged in the pipe axis direction.

At this time, two kinds of first and second grooves 2, 4 having the same pitch p in the circumferential direction of the pipe on the inner surface of the inner grooved pipe and having different twist angles and twist directions with respect to the pipe axis are respectively connected to the pipe axis. In the case of inner grooved pipes provided with a plurality of sets alternately with different processing widths in the circumferential direction, if the torsion angle with respect to the pipe axis of the groove provided in the part with a wider processing width in the pipe circumferential direction is set to 45 ° or more, liquefaction The refrigerant liquid thus collected is easily collected along the groove in the vertical direction of the cross section of the tube, and the heat transfer surface is maintained in a dry state, so that the condensation performance is improved.

On the other hand, the torsion angle of the groove with respect to the pipe axis is 90.
Condensation performance reaches the maximum value in the vicinity of °, but in the range where the torsion angle of the groove is more than 85 ° and up to 90 °, the pitch of increase and decrease of the average wall thickness in the axial direction of the pipe becomes fine, and the bending strength decreases. Breakage is likely to occur during hairpin bending. Therefore, the torsion angle of the groove in the portion where the machining width is large in the circumferential direction of the pipe is set to 45 to 85 °.

[0024] Further, by changing the twisting direction of the groove of the grooved band of the portion where the grooved width in the circumferential direction of the tube is small with respect to the tube axis, the collected refrigerant liquid is discharged in the tube axis direction. In addition, since the swirling flow is suppressed and the heat transfer surface can be prevented from being covered with the refrigerant liquid again, high condensation performance can be maintained.

Further, the torsion angle of the groove of the groove in the portion where the groove width in the circumferential direction of the pipe is narrow is 8 to 45 ° with respect to the pipe axis.
By keeping the temperature in the range, the discharge performance of the refrigerant liquid in the pipe axis direction is improved, and high condensation performance can be maintained. Further, by forming the smooth region 5 between the first grooved band 1 and the second grooved band 3 in the circumferential direction of the pipe, the dischargeability of the refrigerant liquid is further improved and the performance is improved. Can be planned.

It should be noted, is less than the first grooving band 1 width W ₁ and the value of the ratio W ₁ / W ₂ of the width W ₂ of the second groove processing zone 3 is 1.0 to 1.1, the condensation Although the performance is improved, the flow of the refrigerant is obstructed by the groove having the reverse twist angle direction, and the pressure loss is reduced. On the other hand, the value of W ₁ / W ₂ is 3.0
When the pressure exceeds the above range, a swirling flow of the refrigerant liquid easily occurs, the condensed liquid easily spreads over the entire heat transfer surface, and the heat transfer surface is covered and the contact with the refrigerant gas is hindered. For this reason, the condensation performance decreases. Therefore, the value of W ₁ / W ₂ is preferably set to 1.1 to 3.0.

[0027]

EXAMPLES Hereinafter, examples of the inner grooved tube falling within the scope of the present invention will be described in detail by comparing the condensation performance with a comparative example.

First, a groove is formed on one surface of a copper plate by roll rolling, and while this grooved grooved surface is rounded inward, the ends of the plate width are butted and high frequency welded to form an outer diameter of 7.0 mm. An inner grooved tube was manufactured.

The grooves were rolled with a groove depth of 0.2 mm, a groove pitch in the circumferential direction of the tube of 0.41 mm, and a groove having a different twist angle and a different twist direction with respect to the tube axis by changing the processing width in the circumferential direction of the tube. .

This inner grooved tube is disposed inside a double-tube heat exchanger having a length of 3000 mm, and a refrigerant (R) is inserted into the inner grooved tube.
-410A) was inserted thereinto, water was passed through 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 comparative example, a conventional inner grooved tube having a diameter of 7 mm (groove depth 0.2 mm, groove pitch in the circumferential direction of the tube 0.41 mm, twist angle 18 °) was used. The heat transfer performance ratio shown below is based on the evaporation and condensation performance of the comparative example at a refrigerant flow rate of 20 kg / h.

FIG. 2 is a graph showing the relationship between the groove twist angle and the heat transfer performance, with the vertical axis representing the heat transfer performance ratio and the horizontal axis representing the groove twist angle of the grooved band.

As shown in FIG. 2, it was found that the heat transfer performance had a maximum value when the twist angle was 80 to 100 °. However, when the twist angle is in the range of more than 85 ° to 95 °, in a hairpin bending process with a bend radius of 1.2 times the pipe diameter ratio, the breakage rate is high, and it has been found that application of an air conditioner or the like is not practical. .

FIG. 3 shows the heat transfer performance ratio on the vertical axis and the first ratio on the horizontal axis.
FIG. 8 is a graph showing the condensation heat transfer property, taking the ratio W ₁ / W ₂ of the processing width of the grooved band to the processing width of the second grooved band.

In the range falling within the range of the present invention, the maximum value was obtained, and it was found that the condensation performance was superior to that of the comparative example. On the other hand, W1 out of the scope of the present invention
When / W2 is less than 1.0, the condensation heat transfer performance is low, and W1 / W
In the region where 2 exceeds 3.0, the condensation heat transfer performance was reduced.

[0035]

As described in detail above, in the present invention,
A first groove processing band in which a first groove is formed on the inner surface of a metal or alloy pipe, and a pitch in the circumferential direction of the first groove and the metal or alloy pipe which is the same and a twist angle and a twist direction are different; Second
One or a plurality of the second grooving bands on which grooves are formed are alternately arranged, and the torsion angle of the groove having a wider processing width among the first and second grooving bands is 45 to 85 °. By setting the torsion angle of the groove having a narrower processing width to 8 to 45 °, an inner grooved tube having excellent condensation performance can be formed. Further, this is suitable as a condenser for a room air conditioner or the like, and an energy-saving and high-performance condenser can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an inner surface of a tube with an inner groove developed according to an embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the groove torsion angle and the heat transfer performance, with the vertical axis representing the heat transfer performance ratio and the horizontal axis representing the groove twist angle of the grooved band.

FIG. 3 shows the heat transfer performance ratio on the vertical axis, and the ratio W ₁ / W ₂ of the processing width of the first groove processing zone to the processing width of the second groove processing band on the horizontal axis.
FIG. 3 is a graph showing condensation heat transfer properties.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1; 1st groove processing band 2; 1st groove 3; 2nd groove processing band 4; 2nd groove 5;

 ──────────────────────────────────────────────────の Continuing on the front page (72) Nobuaki Hinako 65, Hirasawa, Hadano City, Kanagawa Prefecture Inside the Hadano Plant, Kobe Steel Co., Ltd. Inside

Claims (4)

[Claims] 1. A first grooved band in which a first groove is formed on an inner surface of a metal or alloy tube, and the first grooved band on a different surface of the inner surface of the metal or alloy tube from the first grooved band. A first groove and a second groove processing zone in which a second groove having the same pitch in the circumferential direction of the metal or alloy pipe but having a different twist angle and a different twist direction is formed. One or more grooves are alternately arranged in the circumferential direction of the metal or alloy pipe with different processing widths of the groove processing band and the second groove processing band, and the first and second groove processing bands are formed. An inner grooved pipe characterized in that the torsion angle of the groove having the larger processing width is 45 to 85 ° and the torsion angle of the groove having the smaller processing width is 8 to 45 °. 2. A processing width of a groove processing band having a larger processing width among the first and second groove processing bands is W ₁ , and a processing width of a groove processing band having a smaller processing width is W _2. when the, inner grooved tube according to claim 1, wherein the ratio W ₁ / W ₂ of the W ₁ and the W ₂ is 1.1 to 3.0. 3. The inner grooved pipe according to claim 1, wherein a smooth region is formed between the first grooved band and the second grooved band. 4. The first grooved band and the second grooved band are formed by rolling on the surface of a plate-shaped strip made of metal or alloy, and the strip is rolled in the circumferential direction. The inner grooved pipe according to any one of claims 1 to 3, wherein the pipe is formed by welding.