JPH07103677A - Corrugated fin for heat exchanger - Google Patents

Abstract

PURPOSE:To suppress expansions of a temperature boundary layer and a speed boundary layer and improve heat transfer characteristics by forming louvered pieces each having a specific angle to an air flowing direction at an end of a louver in a wavy corrugated fin in which the louver of a specific shape protrudes. CONSTITUTION:An outer louver 2 and an inner louver 3 are louvered by feeding a bandlike aluminum material to molding rollers at a corrugated fin 1 arranged between flat tubes 4 communicating between tanks of a heat exchanger of an air conditioner for a vehicle, and formed in a wave state by another roller. Louvered pieces 5 are formed at ends of the louvers 2, 3 formed at the fin 1 at an upstream side of the air A passing the fin 1. The pieces 5 are formed, for example, in a triangular shape, and each has a specific angle a from the ends of the louvers 2, 3. Thus, an air flow of a rear end side of the piece 5 is disordered to form a longitudinal vortex flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrugated fin for a heat exchanger which constitutes a part of a cooling cycle used in an air conditioner for automobiles.

[0002]

2. Description of the Related Art As a corrugated fin of a conventional heat exchanger, as shown in, for example, Japanese Patent Laid-Open No. 63-163785, a corrugated fin interposed between flat tubes through which a fluid to be heat exchanged flows is provided. It is disclosed that a slit in the shape of is cut and raised. The cut and raised slits are basically formed in parallel with the direction of the air flow passing through the corrugated fins. Similarly, the slit disclosed in Japanese Patent Laid-Open No. 63-164786 is also formed parallel to the air flow direction.

Further, Japanese Utility Model Laid-Open No. 59-98253 discloses a louver formed obliquely with respect to a corrugated fin. Further, in this reference, a tip portion of the corrugated fin is parallel to the air flow direction. There is disclosed a blade-shaped protrusion that is provided so as to protrude. Furthermore, JP-A-62
Japanese Patent Publication No. 175589 discloses that a bent piece is formed parallel to the airflow direction at the airflow upstream end of the louver.

[0004]

As described above, in the conventional corrugated fin, in order to improve the heat exchange rate with the air, the louvers are arranged in parallel or obliquely with respect to the direction of the air flow. , Was the mainstream. However, in the case where the louvers are formed in parallel, as shown in FIG.
As shown in (a) and (b), due to the turbulence of the air flow formed by the louvers on the upstream side, the temperature boundary layer x in the louvers on the wake side becomes as shown by the dashed line in FIG. Since the bulge is thicker than the temperature boundary layer y on the upstream side, the heat transfer characteristics are deteriorated.

Further, when the louver is inclined at a predetermined angle (θ) with respect to the airflow direction, the airflow flows as shown in FIG. 8A, so that the airflow is separated on the louver surface 100. As shown in 9 (a), the velocity boundary layer T is disturbed. As a result, the heat transfer characteristics are deteriorated and the pressure loss may increase.

Therefore, the present invention is to provide a corrugated fin for a heat exchanger which suppresses the bulging of the temperature boundary layer and the velocity boundary layer and improves the heat transfer characteristics in the louver.

[0007]

Therefore, the present invention is
A corrugated fin for a heat exchanger, which is arranged between the heat transfer tubes, is bent and formed in a wave shape, and has a predetermined shape of a louver protruding from the end of the louver, and passes through the corrugated fin for a heat exchanger. Upstream of the airflow,
At least one cut-and-raised piece having a predetermined angle with respect to the air flow direction is formed.

[0008]

Therefore, according to the present invention, the end of the louver formed on the corrugated fin and the upstream side of the airflow passing through the heat exchanger corrugated fin have a predetermined angle with respect to the airflow direction. By forming at least one cut-and-raised piece that has been cut and raised, the air flow of the louver can be formed into a longitudinal vortex, so that the air that has been heat-exchanged with the louver above the louver and below the temperature boundary layer can be formed. In order to mix the air that has not been heat-exchanged by the louver above the temperature boundary layer and to exchange the momentum between the slow air below the velocity boundary layer and the fast air above the velocity boundary layer, It can be achieved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a corrugated fin for heat exchanger (hereinafter, corrugated fin) 1 according to the present invention.
Is a method of feeding a strip-shaped aluminum material to a forming roller to cut and raise the outer louver 2 and the inner louver 3 and forming the corrugated shape by another roller. The corrugated fins 1 are attached to, for example, a heat exchanger of an air conditioner for a vehicle, and are arranged between flat tubes 4 that communicate between tanks of the heat exchanger, and heat flowing in the flat tubes 4 is distributed between the flat tubes 4. Heat is exchanged between the exchange medium and the air (arrow A) passing through the corrugated fins 1.

Outer louvers and inner louvers (hereinafter collectively referred to as louvers) 2, 3 formed on the corrugated fins 1.
The cut-and-raised piece 5 shown in FIGS. 2A and 2B is formed at the end of the air A passing through the corrugated fins 1 on the upstream side. This cut and raised piece 5
2A has a triangular shape as shown in FIG. 2A, and a notch 6a is vertically formed from the tip of the louver so as to form a predetermined angle α from the tips of the louvers 2 and 3, and this notch is further cut. A cut 6b having a predetermined length is vertically inserted from 6a to form an L-shaped cut 6, and as shown in FIG. 2 (b), a slanted line 6c connecting the ends of the cut 6 formed in the L-shape is formed. The folds are formed by bending to one side. The formation of the L-shaped cut 6 and the formation of the cut-and-raised piece 5 by bending are performed at the same time when the louvers 2 and 3 are formed on the corrugated fin 1.

As described above, by forming the cut-and-raised pieces 5 at the upstream tips of the louvers 2 and 3, as shown in FIGS. 3 and 4 (c), the air flow approaching the tips of the louvers 2 and 3. Since a part of A rises along the cut-and-raised piece 5 formed with a predetermined angle α with respect to the airflow direction, the airflow on the downstream side of the cut-and-raised piece 5 is disturbed, and the vertical vortex flow B Will be formed.

A longitudinal vortex flow B generated on the louvers 2 and 3
Is air D near the louvers 2 and 3 (air that has been heat-exchanged by the louvers 2 and 3) D and air that flows away from the louvers 2 and 3 (air that has not been heat-exchanged by the louvers 2 and 3) C. 4 in order to be able to replace
As shown in (d), since the temperature exchange between the air flow and the louver 2, 3 surface 100 can be efficiently performed, the louver surface 1
The temperature gradient of 00 can be increased, and the development of the temperature boundary layer y can be suppressed as compared with the conventional temperature boundary layer x.

Another shape of the cut-and-raised piece 5 shown in FIGS. 5A and 5B is a square-shaped cut-and-raised piece 5, and the cut-and-raised piece 5 has louvers 2 and 3. A notch 6a is cut from the upstream end with a predetermined angle α, and a notch 6b is cut from the end of the notch 6a in parallel with the louvers 2 and 3, and the notch 6 is formed. From the back end of 6, the cut 6a
It is formed by cutting and bending along a diagonal line 6c, which is bent in parallel with.

The cut-and-raised piece 5 shown in FIGS. 6 (a) and 6 (b) is a triangular cut-and-raised piece 5, but the cut 6a extends vertically from the upstream end of the louvers 2 and 3 on the air flow side. The cut-and-raised piece 5 is formed by cutting the cut-and-raised piece 5 by forming a bent diagonal line 6c from the inner end of the cut 6a at a predetermined angle α and bending along the bent diagonal line 6c. It is what is molded.

Further, the cut-and-raised piece 5 shown in FIGS. 7 (a) and 7 (b) is a triangular cut-and-raised piece 5, and the cut 6a is formed from the upstream end of the louvers 2 and 3 in the same manner as described above. It is formed by vertically cutting a predetermined length, and bending sloping lines 6c and 6c 'are formed left and right so as to form a predetermined angle α from the inner end of the cutting 6a, and one side is formed along the bending sloping line 6c. The cut-and-raised piece 5a is folded back upward, and the other cut-and-raised piece 5b is folded back along the bending oblique line 6c 'to form the cut-and-raised piece 5.

The shapes shown in FIGS. 5 to 7 described above can also achieve the same effects as those described above.

In a heat exchanger of the type in which the louvers shown in FIG. 8 (a) are inclined with respect to the air flow direction, the air flows of the louvers 2'and 3'as shown in FIG. 8 (b). By forming the cut-and-raised piece 5 ′ at the upstream end, the vertical vortex flow B ′ can be formed on the surfaces of the louvers 2 ′ and 3 ′. This longitudinal vortex B ′ allows the exchange of momentum between the air flow and the vicinity of the louver surface, so that the velocity boundary layer S becomes close to the surface 100 as shown in FIG. The velocity gradient is increased and the separation of the airflow can be prevented even at an excessive louver angle θ. Further, by preventing the air flow separation, the pressure loss on the louver surface can be suppressed.

Even in the heat exchanger in which the louvers 2'and 3'are formed obliquely with respect to the air flow direction, the cut-and-raised pieces disclosed in FIGS. 5 to 7 can be used, and the same effect as described above can be obtained. Is something that can be raised.

[0020]

As described above, according to the present invention, at least one cut-and-raised piece having a predetermined angle with respect to the air flow direction is formed at the air flow upstream end of the louver formed on the corrugated fin. By doing so, a longitudinal vortex can be formed on the louver surface, so that the temperature of the airflow and the louver surface can be exchanged, the development of the louver temperature boundary layer can be suppressed, and the heat transfer performance can be improved. You can

Further, in the louver formed so as to be inclined with respect to the air flow direction, since a vertical vortex is formed, separation of the air flow on the louver can be prevented, so that heat transfer performance can be improved. In addition, it is possible to suppress an increase in pressure loss.

[Brief description of drawings]

FIG. 1 is a perspective view showing a part of a heat exchanger according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a cut-and-raised piece of an embodiment according to the present invention, FIG. 2A is a diagram illustrating a cut, and FIG.
Is a perspective view.

FIG. 3 is a perspective view illustrating a vertical vortex flow.

FIG. 4 (a) is a diagram illustrating an air flow that flows over a louver formed in parallel with a conventional air flow, FIG. 4 (b) is a characteristic diagram showing a temperature boundary layer thereof, and FIG. FIG. 4 is a diagram illustrating an airflow flowing over a louver having a cut-and-raised piece according to an embodiment of the present invention, and FIG. 6D is a characteristic diagram showing a temperature boundary layer thereof.

FIG. 5 is an explanatory view illustrating a cut-and-raised piece of another embodiment according to the present invention, in which (a) is a view illustrating a cut.
(B) is a perspective view.

FIG. 6 is an explanatory view illustrating a cut-and-raised piece of another embodiment according to the present invention, in which (a) is a view illustrating a cut.
(B) is a perspective view.

FIG. 7 is an explanatory diagram illustrating a cut-and-raised piece of another embodiment according to the present invention, in which (a) is a diagram illustrating a cut.
(B) is a perspective view.

FIG. 8 (a) is a diagram showing a conventional air flow in a louver formed obliquely to the air flow direction,
(B) is the figure which showed the flow of the airflow when the cut-and-raised piece of the Example which concerns on this invention is formed.

9A is a characteristic diagram showing a conventional velocity boundary layer, and FIG. 9B is a characteristic diagram when a cut-and-raised piece is formed.

[Explanation of symbols]

 1 Corrugated fin 2 Outer louver 3 Inner louver 4 Flat tube 5,5 'Cut and raised piece

Claims (1)

[Claims] 1. A corrugated fin for a heat exchanger, which is arranged between heat transfer tubes, is bent in a wavy shape, and is provided with a louver of a predetermined shape in a protruding manner. A corrugated fin for a heat exchanger, characterized in that at least one cut-and-raised piece having a predetermined angle with respect to the airflow direction is formed on the upstream side of the airflow passing through the corrugated fin.