JPH0926280A - Refrigerant piping with internal surface groove - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat transfer characteristics by forming many grooves in an internal surface in the direction of the flow of a refrigerant, the widths of which have several values. SOLUTION: In the internal surface of a straight pipe 26A constituting a refrigerant piping 26, the number of grooves 31..., 32... is, e.g. 60 in total are formed. Herein, the bottom width B of the groove 31 is set to be 0.33mm for example, and the bottom width (e) of the groove 32 is set to be 0.48mm for example wider than the former. Both grooves 31, 32 are alternately formed. A mixed refrigerant flows spirally with the aid of a capillary phenomenon in the grooves 31, 32 adapted to the physical properties of each refrigerant on the side of an internal wall in the refrigerant piping 26, and hereby the flow of a specific refrigerant is prevented from staying. A high viscosity R134a mainly flows in the wider groove 32 while R32, R125 flow in the narrower groove 31. Accordingly, flow resistance of the R134a is reduced owing to the capillary phenomenon to reduce pressure drop whereby the mixed refrigerant flows smoothly also along the upper part in the refrigerant piping 26 to improve the heat transfer characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner grooved refrigerant pipe having a large number of spiral grooves formed on its inner surface.

[0002]

2. Description of the Related Art Conventionally, air conditioners, refrigerators, refrigerators,
Alternatively, a heat exchanger used for a refrigerating and air-conditioning electric device such as a low-temperature showcase includes a meandering refrigerant pipe and a plurality of fins. In addition, for example, Japanese Patent Publication No. 4-211117 (F
28F1 / 40), a large number of spiral grooves are formed, and the refrigerant flows through these grooves by capillarity so that the refrigerant flows to the upper part of the pipe as well. The refrigerant and the refrigerant pipe are heat-exchanged to improve heat transfer characteristics.

[0003]

When two or more kinds of mixed refrigerants are used as the refrigerant flowing in the refrigerant pipe, the respective refrigerants have different physical properties, particularly viscosity. However, since the width of each groove is the same in the past, if the groove width is set to be narrower in accordance with the low-viscosity refrigerant, the width becomes narrower for the high-viscosity refrigerant, the flow resistance increases, and the pressure loss increases. It gets bigger. As a result, the flow of the highly viscous refrigerant becomes stagnant.

On the contrary, if the groove width is set to be wide in accordance with the highly viscous refrigerant, then the width becomes wide and wide for the low viscous refrigerant, and the capillary phenomenon does not work.

The present invention has been made in order to solve the above-mentioned conventional technical problems. In particular, when two or more kinds of mixed refrigerants are used, the heat transfer characteristics between the refrigerant and the refrigerant pipe are improved and An object of the present invention is to provide a refrigerant pipe capable of suppressing the problem that the mixing ratio of the mixed refrigerant changes.

[0006]

That is, the inner surface grooved refrigerant pipe of the invention of claim 1 is one in which a large number of grooves are formed on the inner surface in the direction in which the refrigerant flows, and the width of each groove is It is formed in any one of a plurality of different widths.

In the refrigerant pipe with an inner groove according to the second aspect of the present invention, a large number of grooves are formed on the inner surface in the direction in which the refrigerant flows,
Refrigerant mixed with at least two kinds flows inside, each groove is formed with a width suitable for the physical properties of any refrigerant, and at least one groove suitable for the physical properties of each refrigerant is formed. It is formed on the inner surface.

In the refrigerant pipe with an inner groove according to a third aspect of the present invention, in each of the above inventions, the groove formed on the inner surface of the refrigerant pipe is formed in a spiral shape in the direction in which the refrigerant flows.

[0009]

According to the refrigerant pipe with internal groove of the invention of claim 1,
Since the width of the groove formed on the inner surface is formed to be one of a plurality of different widths, it is necessary to match the groove width with the characteristics of each refrigerant even when two or more types of mixed refrigerant flow inside. Is possible. Therefore, while preventing an increase in pressure loss due to flow resistance, it is possible to improve the heat transfer characteristics by exchanging heat between the refrigerant and the refrigerant pipe in a wide range on the inner surface of the pipe by the capillary phenomenon. Further, it is possible to suppress the difference in pressure loss due to the flow resistance of each refrigerant due to the capillary phenomenon due to the groove width, and to suppress the fluctuation of the mixing ratio of the mixed refrigerant when the mixed refrigerant flows through the refrigerant pipe. .

According to the inner surface grooved refrigerant pipe of the invention of claim 2, in which the refrigerant in which at least two kinds or more are mixed flows in the inside, the groove formed on the inner surface has a width adapted to the physical properties of any refrigerant. Since at least one groove that matches the physical properties of each refrigerant is formed on the inner surface, the refrigerant is prevented from increasing in pressure loss due to flow resistance, and the refrigerant is spread over a wide range on the inner surface of the pipe due to the capillary phenomenon. It is possible to improve the heat transfer characteristics by exchanging heat between the refrigerant pipe and the refrigerant pipe. Further, it is possible to suppress the difference in pressure loss due to the flow resistance of each refrigerant due to the capillary phenomenon due to the groove width, and to suppress the fluctuation of the mixing ratio of the mixed refrigerant when the mixed refrigerant flows through the refrigerant pipe.

According to the refrigerant pipe with an inner groove of the third aspect of the present invention, in addition to the above respective inventions, the groove is formed in a spiral shape in the direction in which the refrigerant flows. The thermal characteristics can be improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a refrigerant circuit diagram of an air conditioner AC as an embodiment to which the present invention is applied. In FIG. 1, the air conditioner AC includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3,
A refrigeration cycle is configured by connecting the capillary tube 4, the screen-containing modulator 5, the indoor heat exchanger 6, and the accumulator 7 as a decompressor with a refrigerant pipe, and a mixed refrigerant containing an HFC-based refrigerant and It is configured by enclosing a refrigerant and an oil that is compatible. Further, the outdoor heat exchanger 3 and the indoor heat exchanger 6
Are blown by the blowers 41 and 42, respectively.

Here, the refrigerant and oil sealed in the refrigerant circuit differ in evaporation temperature, that is, depending on the application. For example, high temperature equipment such as the air conditioner AC of this embodiment is
An HFC-based mixed refrigerant containing R134a as a refrigerant, for example, a mixed refrigerant of three kinds of R134a, R32, and R125 (refrigerant composition is, for example, R134a is 52% by weight and R32 is 2% by weight).
3% by weight, R125 is 25% by weight), and the oil is a polyol ester oil or an alkylbenzene oil.

The characteristics of each of the refrigerants are as follows. That is, R134a has a boiling point of −26 ° C. and a viscosity of 0.2.
The boiling point of 04 mPa · S, R32 is −53 ° C., and the viscosity is 0.1.
The boiling point of 140 mPa · S and R125 is −48.3 ° C., and the viscosity thereof is 0.145 mPa · S.

The outdoor heat exchanger 3 has a plurality of fins 23, ... Arranged at predetermined intervals as shown in FIG.
And a meandering refrigerant pipe 26 that penetrates through the fins 23.

The fin 23 has a thickness of 100 .mu.m.
It consists of a 120-micron aluminum (including aluminum alloy) thin plate, on the surface of which an acid-based solution (chromic acid,
By immersing the thin aluminum plate in chromate, dichromate, chromic acid / phosphoric acid, phosphoric acid, etc., a rust preventive layer having a thickness of about 2 microns is formed. Further, a black hydrophilic film having a thickness of 5 to 10 microns is formed by coating on the outside of the rust preventive layer. This hydrophilic film is formed in order to make it difficult for water droplets, which become ventilation resistance, to form on the surface of the fins 23, but by making it black, the reflectance of light is reduced and the heat radiation characteristics are improved. ing.

A hole for inserting a pipe is formed in advance in such a fin 23, and the fin 23 is sequentially inserted into a plurality of straight pipes 26A constituting the refrigerant pipe 26 at predetermined intervals. Then, the straight pipe 26A is expanded by applying pressure from the inside, and then the bend pipe 26B is welded to connect the straight pipes 26A. This constitutes the meandering refrigerant pipe 26,
The heat exchanger 3 is completed.

Here, FIG. 3 shows a sectional view of a straight pipe 26A (similar to the bend pipe 26B) constituting the refrigerant pipe 26, and FIG. 4 shows a partially enlarged sectional view thereof. For example, a total of 60 grooves 31, ..., 32 ... Are formed on the inner surface of the straight pipe 26A. Here, the bottom width B of the groove 31 is 0.3, for example.
3 mm, the bottom width e of the groove 32 is wider than that, for example 0.4
It is set to 8 mm, and both grooves 31, 32 are formed alternately.

The height H of the crest 35 for partitioning the grooves 31 and 32 is 0.3 mm, the apex angle θ is 30 degrees, and the tip curvature r.
Is 0.05 mm, and the twist angle when the grooves 31 and 32 are spirally arranged is, for example, 18 degrees. The outer diameter OD of the straight pipe 26A is, for example, 10 mm, and the bottom wall thickness TF is 0.27 mm.
It is.

Since the indoor heat exchanger 6 has the same structure as the outdoor heat exchanger 3 shown in FIG. 2, its explanation is omitted.

In the cooling operation of the air conditioner AC having the above configuration, as shown by the solid line arrow in FIG. 1, the compressor 1, the four-way valve 2, the outdoor heat exchanger 3, the capillary tube 4, the screen-containing modulator 5 are shown. The mixed refrigerant flows in the order of the indoor heat exchanger 6 and the accumulator 7. In this case, the compressor 1
A high-temperature and high-pressure gas refrigerant (mixed refrigerant) is discharged from the inside, flows into the outdoor heat exchanger 3, radiates heat, and is condensed. Then, after being decompressed by the capillary tube 4, it flows into the indoor heat exchanger 6 and evaporates. Therefore, the outdoor heat exchanger 3 becomes a condenser, and the indoor heat exchanger 6 becomes a cooler.

Outside air is ventilated through the outdoor heat exchanger 3 by a blower 41 at a wind speed of 1 m / s, and warm air that has been heated by exchanging heat with the outdoor heat exchanger 3 is diffused outside the refrigerator. . The cool air that has exchanged heat with the indoor heat exchanger 6 and is cooled is supplied to the room by the blower 42.

Here, the mixed refrigerant that has flowed into the outdoor heat exchanger 3 and the indoor heat exchanger 6 is capillarity inside the grooves 31 and 32 on the inner wall side of the refrigerant pipe 26, which are adapted to the physical properties of the respective refrigerants. Therefore, the flow of the specific refrigerant is prevented from being stagnant and the flow of the specific refrigerant does not become stagnant. As mentioned above, R32 and R
Since the viscosity of 125 is low and the viscosity of R134a is high, R134a having a high viscosity flows mainly in the wider groove 32 and R32 and R125 mainly flow in the narrower groove 31 because of its ease of flow. become.

Therefore, due to the capillary phenomenon, the flow resistance of R134a is substantially lowered and the pressure loss is reduced, and the mixed refrigerant smoothly flows into the upper portion of the refrigerant pipe 26 (the straight pipe 26A and the bend pipe 26B). Also, R32 and R125
Also, due to the capillary phenomenon, the upper portion of the refrigerant pipe 26 also flows through the groove 31 without any trouble.

That is, since each refrigerant flows smoothly through the grooves 31 and 32 having a width suitable for its characteristics (particularly, viscosity), the refrigerant and the refrigerant pipe 26 are spread over a wide area on the inner surface of the refrigerant pipe 26. Heat is exchanged and heat transfer characteristics are improved. Therefore, in this case, the heat dissipation characteristics (condensation performance) can be further improved in the outdoor heat exchanger 3, and the heat absorption characteristics (cooling characteristics) can also be improved in the indoor heat exchanger 6 to improve the air conditioner AC. It is possible to improve the cooling capacity.

When the refrigerant pipes having different groove widths are also used as the refrigerant pipes connecting the devices in the refrigeration cycle, the pressure loss of each refrigerant of the mixed refrigerants circulating in the refrigeration cycle is substantially the same. Can be configured to.
Therefore, it is possible to suppress the problem that a specific refrigerant is accumulated in a part of the refrigeration cycle due to the difference in pressure loss of each refrigerant and the mixing ratio of the mixed refrigerant circulating in the refrigeration cycle changes.

On the other hand, during the heating operation, as shown by the broken line arrow in FIG. 1, the compressor 1, the four-way valve 2, the indoor heat exchanger 6, the screen-containing modulator 5, the capillary tube 4, the outdoor heat exchanger 3, The mixed refrigerant flows in the order of the accumulator 7. In this case, the high-temperature and high-pressure gas refrigerant (mixed refrigerant) discharged from the compressor 1 flows into the indoor heat exchanger 6, radiates heat, and is condensed. Then, after being decompressed by the capillary tube 4, it flows into the outdoor heat exchanger 3 and evaporates.
Therefore, the outdoor heat exchanger 3 becomes a cooler, and the indoor heat exchanger 6 becomes a condenser.

The indoor heat exchanger 6 is ventilated by the blower 42 as described above, and the warm air after heat exchange with the indoor heat exchanger 6 is circulated in the room. In addition, the heat transfer characteristics of the heat exchangers 3 and 6 are improved, and the heat dissipation characteristics (heating performance) of the indoor heat exchanger 6 can be further improved and the outdoor heat exchanger 3 also absorbs heat. It is possible to improve the characteristics and improve the heating capacity of the air conditioner AC.

During the defrosting operation, the compressor 1, the four-way valve 2, the indoor heat exchanger 6, as shown by the solid arrow with dots in FIG.
The mixed refrigerant flows in the order of the screen-containing modulator 5, the capillary tube 4, the outdoor heat exchanger 3, the four-way valve 2, and the accumulator 7, and the compressor 1, the solenoid valve 33,
The outdoor heat exchanger 3 and the mixed refrigerant flow, and the outdoor heat exchanger 3
Defrosting is performed.

Further, in the embodiment, a mixed refrigerant of three kinds is used, and
Although the groove having the width of the kind is formed on the inner surface of the refrigerant pipe, two kinds or another kind of another kind of refrigerant may be combined. However, even in that case, a groove having a width that matches the characteristics (especially viscosity) of each refrigerant is formed. Further, although the air conditioner has been described as an example in the embodiment, the present invention is not limited to this, and the present invention is also effective for a refrigerator, a low temperature showcase, and the like.

[0031]

As described in detail above, according to the invention of claim 1, since the width of the groove formed on the inner surface is formed to be any one of a plurality of different widths, the inside is made of two or more kinds. Even when the mixed refrigerant flows, the groove width can be matched to the characteristics of each refrigerant. Therefore, while preventing an increase in pressure loss due to flow resistance, it is possible to improve the heat transfer characteristics by exchanging heat between the refrigerant and the refrigerant pipe in a wide range on the inner surface of the pipe by the capillary phenomenon. Further, it is possible to suppress the difference in pressure loss due to the flow resistance of each refrigerant due to the capillary phenomenon due to the groove width, and to suppress the fluctuation of the mixing ratio of the mixed refrigerant when the mixed refrigerant flows through the refrigerant pipe. .

According to the second aspect of the present invention, in a refrigerant in which at least two kinds or more are mixed, the groove formed on the inner surface is formed with a width adapted to the physical properties of any refrigerant, and Since at least one groove suitable for the physical properties of each refrigerant is formed on the inner surface, the refrigerant and the refrigerant pipe are heated in a wide range of the inner surface of the pipe by the capillary phenomenon while preventing an increase in pressure loss due to flow resistance. It becomes possible to exchange the heat transfer characteristics and improve the heat transfer characteristics.
Further, it is possible to suppress the difference in pressure loss due to the flow resistance of each refrigerant due to the capillary phenomenon due to the groove width, and to suppress the fluctuation of the mixing ratio of the mixed refrigerant when the mixed refrigerant flows through the refrigerant pipe.

According to the invention of claim 3, in addition to each of the above inventions, the groove is formed in a spiral shape in the direction of flow of the refrigerant, so that the heat transfer characteristics between the refrigerant and the refrigerant pipe are improved. You will be able to.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram of an air conditioner as an embodiment of the present invention.

FIG. 2 is a front view of an outdoor heat exchanger as an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a refrigerant pipe (straight pipe or bend pipe).

FIG. 4 is a partially enlarged sectional view of a refrigerant pipe (straight pipe or bend pipe).

[Explanation of symbols]

 AC air conditioner 1 Compressor 3 Outdoor heat exchanger 6 Indoor heat exchanger (heat exchanger) 23 Fins 26 Refrigerant pipe 26A Straight pipe 26B Bend pipe 31, 32 groove

 ─────────────────────────────────────────────────── --Continued front page (72) Inventor Takashi Kawanabe 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A refrigerant pipe having a large number of grooves formed on the inner surface thereof in the direction of flow of the refrigerant, wherein the width of each groove is one of a plurality of different widths. Refrigerant piping. 2. In an inner grooved refrigerant pipe in which a large number of grooves are formed on the inner surface in the direction of flow of the refrigerant, and a refrigerant mixed with at least two kinds or more flows in the inside, each of the grooves is An internal grooved refrigerant pipe, characterized in that it is formed with a width suitable for the physical properties, and at least one groove suitable for the physical properties of each refrigerant is formed on the inner surface. 3. The refrigerant pipe with internal groove according to claim 1 or 2, wherein the groove formed on the inner surface of the refrigerant pipe is formed in a spiral shape in the direction in which the refrigerant flows.