JPH0921593A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a heat-exchanging performance by effectively passing a fluid between the front and rear parts of respective pins in a heat exchanger using fine pin fins. SOLUTION: Flow deflecting members 2c are provided on the bent parts (connecting surfaces) 2b of fine pin fins 2 connected to a tube 1 and the flow deflecting members 2 are arranged so as to be deviated from those provided in adjacent passages. Accordingly, when air is supplied in the direction of an arrow A, the main flow of the supplied air is liable to pass through the rows of pins 2a. At this time, air flow velocity is increased depending on the air passage squeeze operation of the flow deflecting members 2c in the vicinity of positions where the flow deflecting members 2c are provided and static pressure is lowered. On the contrary, the air flow velocity is decreased in positions where the flow deflecting members 2c are not provided and the static pressure is increased, since the air passage squeeze operation of the flow deflecting members 2c does not operate. Since air flow traversing the rows of pins 2a (passing the front and rear parts of pins 2a) is generated owing to the difference of static pressure, a temperature boundary layer can be divided in the front and rear parts of the pins 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving the performance of a heat exchanger using fine fins, and is suitable for use in automobile air conditioners, household air conditioners and the like.

[0002]

2. Description of the Related Art Conventionally, a heat exchanger using this type of fine fin is disclosed in, for example, JP-A-60-162190. In this prior art, the heat exchanger is used as a cooler. In order to improve the drainability of the dew condensation water in some cases, it is described that the arrangement interval of the fine pins is partially increased.

[0003]

By the way, in this type of heat exchanger, by miniaturizing the pins, the temperature boundary layer is finely divided, and the heat transfer coefficient of the pin tips is improved by the tip effect. It is possible to plan. However, on the other hand, since the pin is miniaturized, the surface area of the pin becomes small, which causes a problem that required performance (heat exchange amount) cannot be secured. Therefore, in order to secure this necessary capability, it is necessary to reduce the arrangement interval between the pins and arrange the pins densely.

However, if the spacing between the pins is reduced, the temperature boundary layer of the downstream pin is continuously formed in the temperature boundary layer of the upstream pin in the flow direction of the fluid (such as air). Therefore, the pin tip effect due to the division of the temperature boundary layer cannot be exhibited, and the heat transfer coefficient is lowered. In addition, since the fluid flows along the row of pins arranged parallel to the fluid flow direction, and almost no fluid flows between the front and rear of each pin, the front and rear surfaces of each pin (the front and rear surfaces in the fluid flow direction) Does not contribute as a heat transfer surface and causes a decrease in heat exchange performance.

The present invention has been made in view of the above points,
In a heat exchanger using fine fins, it is an object to improve the heat exchange performance by allowing the fluid to effectively flow between before and after the fine fin portion such as a pin.

[0006]

In order to achieve the above object, the present invention employs the following technical means. In the invention according to claim 1, a tube (1) having a flat cross section
And fine fins (2) for promoting heat transfer between the tube (1) and the fluid flowing outside the tube (1)
And the fine fins (2) are arranged in rows along the flow direction of the fluid.
And a joining surface (2b) that is bent between the rows of the fine fin portions (2a) and is joined to the tube (1).
And a flow deflector (2c) provided on the joint surface (2b) for deflecting the flow of the fluid to form a flow crossing between the fine fin portions (2a). The flow deflector (2c) formed in (2b) is
The heat exchangers are arranged at positions displaced from each other with respect to the flow of the fluid.

According to a second aspect of the present invention, in the heat exchanger according to the first aspect, the flow deflector (2c) is integrally cut and raised from the joint surface (2b). . According to a third aspect of the invention, in the heat exchanger according to the first or second aspect, the flow deflector (2
c) is characterized in that the flow of the fluid is locally restricted to generate a difference in the static pressure of the fluid at the installation site of the fine fin portion (2a).

According to a fourth aspect of the present invention, in the heat exchanger according to any one of the first to third aspects, the flow deflector (2c) is a triangle whose top is directed upstream in the fluid flow direction. It is characterized in that it is cut and raised from the joint surface (2b) with the base of this triangle as a fulcrum. In the invention according to claim 5, a tube (1) having a flat cross section, the tube (1),
A fine fin (2) for promoting heat transfer with a fluid flowing outside the tube (1), the fine fin (2) being arranged in a row along the flow direction of the fluid. Fine fin portion (2a) and this fine fin portion (2a
The joining surface (2b) formed by bending between the rows of (a) and joined to the tube (1) and the joining surface (2b) provided on the joining surface (2b) to deflect the flow of the fluid and to form the fine fin portion ( Two
a) A flow deflector (2d) forming a transverse flow between the a), the flow deflector (2d) being constituted by a vortex generator for generating a vortex in the fluid flow. .

According to a sixth aspect of the invention, in the heat exchanger according to the fifth aspect, the vortex generator has the joint surface (2).
It is composed of two cut-and-raised pieces (2e, 2e) integrally cut and raised from b) with a predetermined cut-and-raised angle (β).
2e) is characterized in that the flow paths between them are diagonally arranged with a predetermined deflection angle (α) in a direction in which the interval gradually narrows toward the downstream side of the fluid.

The reference numerals in parentheses of the above-mentioned means indicate the correspondence with the concrete means described in the embodiments described later.

[0011]

According to the inventions of claims 1 to 4,
By arranging the flow deflectors at positions deviated from each other with respect to the fluid flow, it is possible to effectively form a fluid flow that crosses the row of fine fin portions such as pins (passes through the fine fin portions). The temperature boundary layer before and after the fine fin portion can be divided.

That is, as in the prior art, an air flow is formed along the rows of fine fins, and the entire row of fine fins (pin row) is buried in one continuous temperature boundary layer. By eliminating the phenomenon, the tip effect of each fine fin portion can be effectively exhibited, the heat transfer coefficient can be greatly improved, and the effective heat transfer area can be increased. Therefore, the heat exchange performance can be effectively improved in the heat exchanger using the fine fins.

In addition to the above, according to the invention of claim 2,
Since the flow deflector is integrally cut and raised from the joining surface of the fine fins, the flow deflector can be easily manufactured at low cost. Further, in the invention according to claims 5 and 6, since the flow deflector is composed of a vortex generator that generates a vortex in the fluid flow, this vortex generates a velocity component in a direction perpendicular to the fluid flow, A fluid flow can be effectively formed across a row of fine fins (pins).

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. (First Embodiment) FIG. 1 is a perspective view of an essential part of a heat exchanger according to the first embodiment, and a case where the heat exchanger of this embodiment is applied to a refrigerant condenser of an automobile air conditioner will be described.

The heat exchange section of the heat exchanger is composed of the tube 1 and the fine fins 2. The tube 1 is composed of an aluminum multi-hole flat tube manufactured by extrusion molding. In the tube 1, a large number of refrigerant passage holes 1 a formed in parallel are provided.
The fine fin 2 is composed of a fine pin fin in which a large number of fine pins (fine fin portions) 2a are integrally formed by roller-molding an aluminum clad material (plate thickness is, for example, about 0.1 mm) clad with a brazing material. There is. here,
In this example, the cross-sectional shape of the pin 2a is set to a rectangular shape as shown in FIG. 2, and the rectangular size of the pin 2a is, for example, about 0.1 mm on a side. Also, the pin 2a
Form a pin row (see FIG. 2) parallel to the flow direction A of the heat exchange fluid, air. The distance (pitch) between the pins 2a is, for example, about 0.2 mm.
The height of a is, for example, about 8 mm.

The fine fins 2 are bent many times in the direction perpendicular to the air flow direction A (longitudinal direction of the tube 1) at both ends of the fine pins 2a for brazing to the tube 1, and The bent portion 2b is formed as a flat surface portion having a predetermined width dimension (for example, about 16 mm) and constitutes a joint surface to be brazed to the flat surface of the tube 1.

In this example, as shown in FIG. 1, the fine fins 2 are bent so as to have a triangular bent cross section when viewed from the air flow direction A. Therefore, at the cross-sectional position adjacent to the brazing bent portion 2b, two rows of pin rows and the bent portion 2b are alternately formed as shown in FIG. On the other hand, in the bent portion 2b, the flow deflector 2c
Is cut and raised integrally. This flow deflector 2
In the present example, c is formed into an isosceles triangle with its top facing upstream in the air flow direction A, and the flow deflector 2c is cut and raised with the bottom of this isosceles triangle as a fulcrum. The formation position of the flow deflectors 2c is set so that the flow deflectors 2c of the adjacent flow paths are displaced from each other (the position of the staggered arrangement) as shown in FIG.

Although FIG. 1 shows a state in which two stages of tubes 1 are arranged vertically and fine fins 2 are provided between them, the actual heat exchanger structure is a large number of stages vertically. The tubes 1 are arranged, and the fine fins 2 are arranged between the tubes 1. Then, the brazing material clad to the fine fins 2 is melted in a heating furnace, and the tube 1 and the fine fins 2 are integrally brazed.

Here, as the heat exchanger structure, a plurality of tubes 1 cut into a predetermined length are arranged in parallel in the vertical direction of FIG. 1, and both ends thereof are communicated with a header tank, respectively. A so-called multi-flow type is preferable, but a heat exchanger structure such as a so-called serpent type in which the tube 1 is bent and formed in a meandering shape in multiple steps in the vertical direction of FIG. 1 can also be adopted.

Next, the operation of the heat exchanger according to the first embodiment having the above structure will be described. When air is blown in the direction of arrow A by a blower (not shown), the main flow of blown air tends to flow between the rows of pins 2a. At this time, the flow deflector 2c is provided on the bent portion 2b of the fine fin 2, and the flow deflector 2c is located at a position (a staggered arrangement) offset from that of the adjacent flow passage. Since it is arranged, in the vicinity of the arrangement position of the flow deflector 2c,
Due to the action of the flow deflector 2c to throttle the air flow path, the air flow velocity becomes faster and the static pressure becomes lower. On the contrary, the flow deflector 2c
At a position where is not provided (a portion apart from the flow deflector 2c), the air flow restricting action of the flow deflector 2c does not occur, so the air flow velocity becomes slow and the static pressure becomes high.

As a result, as shown by the arrow B in FIG. 2, from the position where the flow deflector 2c is not installed and the static pressure is high to the position where the flow deflector 2c is installed and the static pressure is low. Air flows toward. This flow causes a flow of air across the row of pins 2a (passes in front of and behind the pins 2a), thus disrupting the thermal boundary layer in front of and behind the pins 2a. That is, in the prior art, the air flow C is formed along the row of pins as shown in FIG. 3, and the entire pin is buried in one continuous temperature boundary layer. However, according to the first embodiment, FIG.
By eliminating the flow phenomenon shown in Fig. 2, the tip effect of each pin 2a can be effectively exhibited, and the heat transfer coefficient can be greatly improved, and
The effective heat transfer area can be increased.

In particular, the root of the pin 2a tends to reach a high temperature due to heat conduction from the high-temperature refrigerant flowing in the tube 1, but the flow deflector 2c is formed in the bent portion 2b of the fine fin 2. Since it is close to the root of the pin 2a, the effect of promoting heat transfer by the air flow deflection of the flow deflector 2c is great. The flow deflector 2c shown in FIGS.
Is formed in a triangular shape, but even in a rectangular shape,
An air flow restricting action is generated to generate a static pressure difference in the air flow path, and an air flow can be generated across the row of pins 2a. Therefore, in the first embodiment, the shape of the flow deflector 2c is not limited to the triangular shape. (Second Embodiment) FIGS. 4 to 7 show a second embodiment.
The difference from the first embodiment will be described below. In this embodiment, the fine fins 2 are bent and formed in a rectangular shape as shown in FIG. The flow deflector 2d of the present example locally restricts the flow of air to form a vortex generator that generates a vortex. Specifically, the flow deflector 2d that forms the vortex generator is bent. It is composed of two cut-and-raised pieces 2e and 2e which are integrally cut and raised from the portion (bonding surface) 2b at a predetermined cut-and-raised angle β (see FIGS. 5 and 6). The two cut-and-raised pieces 2e, 2e are obliquely arranged with a predetermined deflection angle α in a direction in which the flow path between them is gradually narrowed toward the downstream side of air. Of the two cut-and-raised pieces 2e, 2e, only the one on the left side of FIG. 4 is shown in FIGS.

In the second embodiment, as shown in FIGS. 4 and 7, the flow deflector 2d is provided only at one position on the air inlet side of the fine fin 2, but the air flow direction A of the fine fin 2 is A.
If the flow path length is long, the deflectors 2d may be provided at a plurality of locations in the air flow direction A. Next, the operation of the heat exchanger according to the second embodiment having the above structure will be described. The air blown in the direction of arrow A by a blower (not shown) is as follows.
An attempt is made to pass through "a flow deflector (vortex generator) 2d composed of two cut-and-raised pieces 2e, 2e" provided on the air inlet side of the fine fin 2. At this time, since the two cut-and-raised pieces 2e, 2e are cut and raised diagonally from the bent portion (joint surface) 2b with a predetermined deflection angle α and a cut-and-raised angle β, the diagonal cut-and-raised shape is formed. Along with this, an air flow is generated, and a vortex flow (swirl flow) shown in FIG. 6 is formed at a portion immediately after the flow deflector 2d.

Since the deflection angles α of the two cut-and-raised pieces 2e, 2e constituting the flow deflector 2d are directed in opposite directions, as shown in FIG. 4, the swirling direction of the swirling flow is It goes in the opposite direction. That is, two vortex flows whose turning directions are opposite to each other are formed immediately after the two cut-and-raised pieces 2e, 2e. Since these two vortex flows each have a velocity component in the lateral direction (direction perpendicular to the A direction) with respect to the air flow direction A, they cross the row of the pins 2a (passes in front of and behind the pin 2a).
An air flow (refer to part B in FIG. 7) is generated, and the temperature boundary layer before and after the pin 2a can be divided. Therefore, similarly to the first embodiment, the tip effect of each pin 2a can be effectively exhibited, the heat transfer coefficient can be greatly improved, and the effective heat transfer area can be increased.

In the above first and second embodiments, the case where the present invention is applied to the refrigerant condenser has been described, but the present invention is not limited to the refrigerant condenser, and the refrigerant evaporator and further the tube 1 are described. It is also applicable to a radiator for automobiles, a heater core for heating, etc., in which water flows as a heat exchange fluid, and is widely applied to heat exchangers in general. Further, the fine fin of the present invention is not limited to the illustrated pin-shaped one,
For example, it may be a slit fin formed by cutting a slit, or an offset fin in which the slit fins are alternately raised.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a heat exchanger showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a form of air flow in the first embodiment.

FIG. 3 is an explanatory diagram illustrating a form of an air flow in the related art.

FIG. 4 is a perspective view of a main part of a heat exchanger showing a second embodiment of the present invention.

FIG. 5 is an enlarged perspective view of a vortex generator in the second embodiment.

FIG. 6 is an enlarged perspective view showing how vortices are generated by the vortex generator in the second embodiment.

FIG. 7 is an explanatory diagram illustrating the form of air flow in the second embodiment.

[Explanation of symbols]

1 ... Tube, 2 ... Fine fin, 2a ... Pin (fine fin portion), 2b ... Bent portion (joint surface), 2c, 2d ... Flow deflector, 2e ... Cut and raised piece.

Claims (6)

[Claims] 1. A tube having a flat cross section, a fine fin for promoting heat transfer between the tube and a fluid flowing outside the tube, the fine fin including The fine fin portions arranged in a row along the flow direction, the joint surface that is bent between the rows of the fine fin portions, and is joined to the tube, and the flow surface of the fluid that is provided on the joint surface. And a flow deflector that forms a flow that crosses between the fine fins, and the flow deflectors formed on the adjoining joint surfaces are located at positions displaced from each other with respect to the fluid flow. A heat exchanger characterized by being arranged. 2. The heat exchanger according to claim 1, wherein the flow deflector is integrally cut and raised from the joint surface. 3. The flow deflector is configured to locally throttle the flow of the fluid to generate a difference in static pressure of the fluid at the installation site of the fine fin portion. The heat exchanger according to Item 1 or 2. 4. The flow deflector is formed in a triangle with its top facing toward the upstream side in the fluid flow direction, and is cut and raised from the joint surface with the base of this triangle as a fulcrum. The heat exchanger according to any one of claims 1 to 3. 5. A tube having a flat cross section, a fine fin for promoting heat transfer between the tube and a fluid flowing outside the tube, the fine fin including The fine fin portions arranged in a row along the flow direction, the joint surface that is bent between the rows of the fine fin portions, and is joined to the tube, and the flow surface of the fluid that is provided on the joint surface. And a flow deflector that deflects the light to form a flow that crosses between the fine fin portions, and the flow deflector is configured by a vortex generator that generates a vortex in the fluid flow. The heat exchanger according to claim 1 or 2. 6. The vortex generator is composed of two cut-and-raised pieces integrally cut and raised from the joint surface with a predetermined cut-and-raised angle, and the two cut-and-raised pieces are located between the cut-and-raised pieces. The heat exchanger according to claim 5, wherein the flow passages are arranged obliquely to each other with a predetermined deflection angle in a direction in which a distance between the flow passages gradually decreases toward a downstream side.