KR100606332B1 - Flat tube for heat exchanger for use in air conditioning or refrigeration systems - Google Patents

Abstract

The present invention relates to a flat tube for a heat exchanger of an air conditioner, wherein a refrigerant inlet is formed and a plurality of first and second headers connected to both sides and the first and second headers are connected to each other so that the refrigerant introduced into the header passes. Air-conditioning is provided through the heat dissipation fins so as to easily exchange heat in the space between the plurality of flat tubes arranged at a predetermined interval along the longitudinal direction of the first and second header, the flow path of the first tube and the adjacent flat tube In the heat exchanger of the device, at least one micro-projection band 42a is formed on the inner wall surface of the flow path 42 of the flat tube 40 in the longitudinal direction of the flat tube to disturb the refrigerant to promote heat exchange. The cross section of the flow passage 42 is generally rectangular in cross section, and the cross section of the micro protrusion 42a has an arc cross section, and the cross section area Ae of the fine protrusion belt is 1.4 to the cross section of the flow passage At. 2 Since it is .9%, it has the effect of increasing the efficiency of the system by improving the pressure loss while increasing the heat transfer performance.

Description

Flat tube for heat exchanger for use in air conditioning or refrigeration systems

1 is an exploded perspective view showing a heat exchanger of an air conditioner to which a conventional flat tube is applied;

2 is a detailed cross-sectional view of the flat tube of FIG.

Figure 3 is a perspective view showing another example of a conventional flat tube,

4 is a perspective view showing one embodiment of a flat tube of the present invention;

5 is a detailed view of the cross-sectional shape of the flow path of FIG. 4;

6 is a cross-sectional view showing various embodiments of the flat tube of the present invention;

7 is a graph showing a comparison of the heat dissipation of a heat exchanger to which a conventional flat tube is applied and a heat exchanger to which a flat tube of the present invention is applied;

8 is a graph showing a comparison of the pressure drop between the heat exchanger to which the conventional flat tube is applied and the heat exchanger to which the flat tube of the present invention is applied.

<Description of the symbols for the main parts of the drawings>

40: flat tube 42: euro

42a: fine protrusion band

The present invention relates to a flat tube for a heat exchanger of an air conditioner.

In the heat exchanger of the air conditioner, particularly in the heat exchanger applied to the vehicle condenser, a flat tube is generally used to increase the heat transfer of the refrigerant.

1 is an exploded perspective view showing a condenser to which a conventional flat tube is applied, which is disclosed in US Pat. No. 4,998,580. As shown in the drawing, the slots 4 are formed in the opposite directions of the two headers 1 and 2, and the slots 4 have flat tubes 10 into which both ends 6 and 8 are fitted. Installed at predetermined intervals along the longitudinal direction, the cap 12 is welded to the upper end of the header 1, the connector 14 is welded to the lower end of the header 2, the pipe 16 is connected, Cap 18 is welded to the lower end of the other header 2, the connector 20 is connected to the upper end of the other header (2). The corrugated fins 22 are installed between the flat tubes 10 to increase the heat exchange rate, and reinforcement members 24 and 26 are installed at the upper and lower sides of the condenser to increase the rigidity of the condenser.

As shown in FIG. 2, a plurality of flow paths P1 and P2 are formed by welding the spacer 28 curved in a sinusoidal shape in the flat tube 10.

On the other hand, as another example of the conventional flat tube as shown in Figure 3, there is also disclosed a flat tube 30 of an extruded tube extruded to form a plurality of passages (P3) therein.

However, in the heat exchanger having a pleat fin and a flat tube, the performance of the heat exchanger is determined by the degree of heat transfer acceleration on the side of the pleat fin and the degree of heat transfer acceleration on the side of the flat tube. The heat transfer acceleration degree and flow characteristics of the refrigerant are determined by the heat transfer area and the geometry of the formed hole 32.

In general, as the number of holes formed in the flat tube, that is, the number of flow paths increases, the heat transfer area increases, thereby facilitating heat transfer. However, as the number of holes (euro) increases, the pressure loss also increases. Increasing the pressure loss will increase the compressor load of the refrigeration system, resulting in increased vehicle fuel economy and reduced efficiency of the refrigeration system. Therefore, the heat transfer performance is increased compared to the conventional flat tube is required to develop a flat tube that can minimize the pressure loss.

Conventionally, U.S. Patent No. 4,998,580 limited the hydraulic diameters of the flow paths P1 and P2 to only a small range to limit heat transfer, but there was a problem in that the pressure loss increased and ultimately the efficiency of the system was limited.

Accordingly, the present invention has been made to meet the above requirements and to solve the problems, and an object of the present invention is to provide a flat tube for a heat exchanger of an air conditioner to increase the efficiency of the system by improving the pressure loss while increasing the heat transfer performance. have.

The flat tube for the heat exchanger of the air conditioner according to the present invention for achieving the above object, the refrigerant inlet is formed and connected to the first header, the second header and the first header, which are erected on both sides, and flowed into the header. A plurality of flat tubes are extruded to form a plurality of flow paths to allow the refrigerant to pass therethrough, and are arranged at predetermined intervals along the length direction of the first and second headers, and the spaces between adjacent flat tubes are easily connected with air. In a heat exchanger for an air conditioner having heat radiating fins interposed therebetween, at least one micro-projection band is formed along the longitudinal direction of the flat tube to disturb the refrigerant to promote heat exchange on the inner wall of the flat tube. The cross section of the cross section is generally rectangular cross-section, the cross section of the micro-projection strip is arc cross-sectional shape, the cross-sectional area (Ae) of the micro-projection strip of the flow path cross section (At) It is characterized by being 1.4 to 2.9%.

The height He of the fine protrusion band is preferably 9.7 to 29.1% of the height of the flow path (Ht: the protrusion direction of the fine protrusion band).

The width We of the fine protrusion band is preferably 10.7 to 26.7% of the width Wt of the flow path.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Flat tube of the present invention, the refrigerant inlet is formed, the first and second headers are formed on both sides, the first and second headers connecting the first, the second header is extruded so that a plurality of flow paths are formed to pass through the refrigerant introduced into the header And a plurality of flat tubes arranged at predetermined intervals along the length direction of the first and second headers, and the heat exchanger for an air conditioner having heat radiating fins interposed therebetween so as to easily exchange heat with air in an adjacent space between the flat tubes. (See Figure 1)

Figure 4 is a perspective view showing a flat tube according to an embodiment of the present invention, Figure 5 is a detailed view of the cross-sectional shape of the flow path of FIG. As shown, the flat tube 40 of the present invention is formed by extrusion processing, in which a plurality of (7) flow paths 42 through which the refrigerant passes are adjacent in the width direction of the extruded tube 40. It is formed along the longitudinal direction, the inner wall surface of the flow path 42 of the flat tube 40 fine each one in the upper and lower sides along the longitudinal direction of the flat tube 40 so as to disturb the refrigerant to promote heat exchange. A protruding band 42a is formed. The cross section of the flow passage 42 is generally rectangular in cross section, and the cross section of the fine protrusion strip 42a has an arc cross section. The micro protrusions 42a formed in the flow passage 42 may be formed in various numbers at various positions as shown in FIGS.

 The cross-sectional area Ae of the micro-projection band is 1.4 to 2.9% of the channel cross-sectional area At, and the height He of the micro-projection band is 9.7 to the height of the channel (Ht: protruding direction of the micro-projection band). 29.1%, and the width We of the fine protrusion band is preferably 10.7 to 26.7% of the width Wt of the flow path.

Hereinafter, a flat tube without a conventional micro-projection band and a heat exchanger to which the flat tube of the present invention is applied will be described as a graph together with test data.

The test conditions are as follows.

Operating Refrigerant: R134a

Air velocity (m / s): 1, 2, 3, 4, 5

Refrigerant Inlet Pressure: 16.7 kg / ㎠

Refrigerant superheat: 20 ℃

Refrigerant supercooling: 4 ℃

Air inlet temperature: 35 ℃

In this test, the conventional flat tube used a flat tube having eight flow paths in which no micro projection band was formed.

In the present test, the flat tube of the present invention includes a flat tube having seven flow paths having two fine protrusion bands (hereinafter referred to as 'type 1 of the present invention'), and six flow paths having two fine protrusion bands. An excitation flat tube (hereinafter referred to as 'type 2 of the present invention') and a flat tube having six flow paths having four fine protrusion bands (hereinafter referred to as 'type of the present invention') were used. In addition, the cross-sectional area, height, and width of the micro-projection band of the flat tube of the present invention were specified in the flat tube as shown in Table 1 in this test.

TABLE 1

Specification Ae / At We / Wt He / Ht Invention type 1 0.017 0.107 0.029 Invention type 2 0.144 0.267 0.177 Invention type 3 0.029 0.291 0.097

7 is a graph showing a heat dissipation amount of a heat exchanger to which a conventional flat tube is applied and a heat exchanger to which a flat tube of the present invention is applied. However, the present invention has almost no difference between the conventional and the present invention. Considering that there are eight and six or seven flow paths of the flat tube of the present invention, it can be seen that the heat dissipation amount is remarkably improved.

As shown in FIG. 8, the heat exchanger to which the flat tube of the present invention is applied has a significant decrease in passage resistance compared to the heat exchanger to which the flat tube is applied.

Reducing the number of flow paths in a flat tube generally reduces the pressure loss but also reduces the heat transfer performance. In the present invention, the heat transfer performance generated by reducing the number of flow paths and reducing the number of flow paths of a conventional flat tube is reduced. The deficiency is recovered by forming a fine protrusion band in the flow path.

The flat tube is accompanied by a process of phase change of the refrigerant condensation and evaporation depending on the conditions of use. In this case, it is well known that the liquid film has a high thermal resistance and thus suppresses heat transfer compared to the gas phase. The flat tube used in the prior art does not have a separate device for evenly distributing such a liquid film, and in particular, the liquid film is thickly distributed in a small dry area (condensation completion area) with a large influence of gravity, so that heat transfer is not performed well.

However, the micro-projection band formed in the present invention evenly distributes the liquid film distribution having a large thermal resistance, thereby reducing the thickness of the liquid film and increasing the turbulence of the flow to promote heat transfer. This thin and evenly distributed liquid film distribution, as well as the reduction in the number of flow paths (a decrease in the flow velocity due to the increase of the cross-sectional area), may contribute to the reduction of the pressure drop. However, if the size of the microprotrusion band is too large, it does not have a great effect on reducing the pressure drop but may lead to an increase in the pressure drop. Therefore, a flat tube having an appropriately sized microprotrusion band for the flow path should be used. .

The present invention is not limited to the above embodiment and can be modified in various ways.

By the flat tube for heat exchanger of the air conditioner according to the present invention, the pressure loss is reduced while securing heat transfer performance equal to or higher than that of the conventional flat tube, thereby reducing the compressor load of the cold air system and reducing the fuel consumption of the automobile and refrigeration system. There is an effect that can effectively increase the efficiency of.

Claims (3)

 The first and second headers formed on both sides of the refrigerant outlet, and the first and second headers connected to the first and second headers are extruded to form a plurality of flow paths through which the refrigerant introduced into the header passes. In the heat exchanger for air conditioning equipment having a plurality of flat tubes arranged at predetermined intervals along the longitudinal direction of the header and the heat dissipation fin is interposed so as to easily exchange heat in the space between the adjacent flat tube, At least one micro-projection strip is formed along the longitudinal direction of the flat tube in the inner wall surface of the channel of the flat tube to promote the heat exchange by disturbing the refrigerant, and the cross section of the channel is generally rectangular cross-section, and the micro-projection is The cross section of the strip is circular cross section, The cross-sectional area (Ae) of the fine protrusion band is 1.4 ~ 2.9% of the flow path cross-sectional area (At) flat tube for the heat exchanger of the air conditioning equipment. The method of claim 1,  The height (He) of the fine protrusion band is 9.7 ~ 29.1% of the height of the flow path (Ht: protruding direction of the fine protrusion band) flat tube for the heat exchanger of the air conditioning equipment. The method of claim 1,  The width (We) of the fine protrusion band is 10.7 ~ 26.7% of the width (Wt) of the flow path flat tube for the heat exchanger of the air conditioning equipment.

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