Heat exchanger and fabrication method thereof

Abstract

A heat exchanger having an aluminum main body is provided. The aluminum main body has heat exchange medium passages that allow the heat exchange medium to circulate, and fins for heat exchange extending outwards from the surface thereof. A method of fabricating the heat exchanger is also provided. The aluminum main body with heat exchange medium passages is formed by stretching or extrusion. The fins are shaped on the external surface of the aluminum main body through skiving. Since the main body and the fins are integrally formed, no extra combined thermal resistance exists between the fins and the main body, and thus the heat exchanger of the present invention has high heat exchange efficiency. Moreover, the method of fabricating the heat exchanger of the present invention has simple processes, and can ensure consistent product quality, and meanwhile does not use expensive copper tubes, thus reducing the cost effectively.

Description

FIELD OF THE INVENTION

The present invention relates to a heat exchanger and a fabrication method thereof. More particularly, the present invention relates to a heat exchanger serving as an evaporator or a condenser in a refrigeration system and a fabrication method thereof.

BACKGROUND OF THE INVENTION

Heat exchanger is an important component of a refrigerator and an air-conditioner. A heat exchange medium in the heat exchanger absorbs or releases heat through the change of the state, so as to achieve heat transfer. For example, the heat exchanger for the air-conditioner includes an indoor heat exchanger (evaporator) and an outdoor heat exchanger (condenser). The evaporator is a direct refrigeration device in the refrigeration system. Low-pressure liquid refrigerant absorbs heat and evaporates in the evaporator, so as to lower the ambient air temperature. The condenser transfers the heat absorbed by the refrigerant in the evaporator and the compressor into the outdoor air.

The conventional heat exchanger has a structure as shown in FIG. 1, and includes copper tubes and fins. The copper tubes are usually made of copper. The fins are usually made of aluminum sheets of 0.1-0.2 mm thickness. The aluminum mentioned in the present invention refers to pure aluminum and aluminum alloy. The spacing between the fins is 1.5-2.5 mm. The process generally includes fitting the aluminum fins onto the copper tubes and then expanding the copper tubes to fix the fins, or integrating the fins and the copper tubes by welding or riveting. However, in this process, an extra combined thermal resistance exists between the fins and the copper tubes, and the overall rigidity is poor, and the heat transfer performance is undesirable, thus affecting the energy efficiency ratio of the heat exchanger. To increase the heat exchange area, technicians have developed wavy fins and slit fins. However, as this process is complex and dust and dirt are easy to deposit on the fins, this technique is not well developed. Besides, as the price of the copper tubes is rising greatly in recent years, and thus the designers are determined to change the above structure.

In view of the above problems, with the development of the technique, in order to reduce the cost of raw materials, a heat exchanger using hollow aluminum tubes instead of the copper tubes is designed, but a bonding process like expansion or welding is still employed. After a performance test, it is found that as the expandability and compactness of the aluminum tube are unsatisfactory, the refrigerant leakage of the heat exchanger may occur, and obviously, the heat exchange efficiency cannot meet the requirements.

SUMMARY OF THE INVENTION

The present invention is directed to solve the problems that the heat exchanger is high in cost, the process is complex, and the heat exchange efficiency is low in the prior art. Thus, a heat exchanger and a fabrication method thereof are provided to reduce the cost of raw materials, simplify the process, and enhance the heat exchange efficiency.

To achieve the above objective, a technical scheme of a heat exchanger having an aluminum main body is provided. The aluminum main body has heat exchange medium passages that allow a heat exchange medium to circulate, and fins for heat exchange extending outward from the surface of the aluminum main body.

The fins are preferably of a sheet structure and formed on the main body through skiving.

The thickness, height, and spacing of the fins are determined according to a heat exchange amount and a force of the wind resistance.

Further, the heat exchanger is bent into a shape of “S”, “C”, or helix.

A transverse cross-section of the aluminum main body may be of any shape, preferably, rectangular or trapezoidal shaped, and the fins are disposed on two opposite sides of the aluminum main body.

Moreover, the heat exchanger further includes a supporting plate on which the heat exchanger is mounted and fixed, and tube joints for connecting the heat exchange medium passages inside the main body and an external heat exchange medium piping are disposed at both ends of the main body.

The transverse cross-section of the heat exchange medium passages is in a shape of round, triangle, quadrangle, or polygon.

One main body has a plurality of heat exchange medium passages therein.

Meanwhile, the present invention provides a method of fabricating a heat exchanger, which includes the following steps.

A1. An aluminum main body is fabricated. An aluminum tube having heat exchange medium passages that allow a heat exchange medium is formed through stretching or extrusion.

B1. A heat sink is fabricated. Fins are shaped through skiving on an external surface of the aluminum tube formed in Step A1.

Furthermore, the present invention further includes the following steps after Step B1.

C1. The fins are pushed. The fins are adjusted to form a certain angle with respect to the surface of the main body.

D1. The heat exchanger with fins relieved thereon is bent into a desired shape.

In the heat exchanger of the present invention, as the main body and the fins are integrally formed, the extra combined thermal resistance existing in the conventional heat exchanger is avoided between the fins and the main body. So, the overall thermal resistance is reduced and the heat exchange efficiency is enhanced. In the method of fabricating the heat exchanger of the present invention, as the fins are formed through skiving on the aluminum profile that constitutes the main body, the process is simplified, the consistency of product quality is effectively ensured, and meanwhile the expensive copper tubes are saved, thus greatly lowering the cost. Moreover, the heat exchange medium passages are formed by extruding the aluminum material, so the hermeticity is good, and the leakage of the heat exchange medium can be effectively prevented. Meanwhile, the required heat exchange medium passages can be conveniently formed through extrusion. The heat exchanger can be bent into any desired shape after the fins are shaped. Compared with the prior art in which multiple copper tubes are welded, no welding seams and welding spots are formed, thereby effectively avoiding the fatal defect of the leakage of heat exchange medium in the heat exchanger. Further, the heat exchanger formerly in the strip shape can be bent into any desired shape according to the requirements, and thus the present invention is more convenient and flexible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic three-dimensional structural view of conventional finned copper tubes;

FIG. 2 is a schematic three-dimensional structural view of a heat exchanger according to a first embodiment of the present invention;

FIG. 3 is a schematic three-dimensional structural view of the heat exchanger after being bent according to the first embodiment of the present invention;

FIG. 4 is a schematic assembly view of a heat exchanger with tube joints according to a second embodiment of the present invention;

FIG. 5 is a schematic three-dimensional structural view of the heat exchanger with tube joints according to the second embodiment of the present invention;

FIG. 6 is a schematic three-dimensional structural view of a heat exchanger with tube joints and a supporting plate according to a third embodiment of the present invention;

FIG. 7 is a schematic three-dimensional view of the heat exchanger with supporting plates of another type according to the third embodiment of the present invention;

FIG. 8 is a schematic three-dimensional structural view of a heat exchanger bent into the shape of “C” according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiment 1

As shown in FIG. 2, the heat exchanger 100 of this embodiment includes an aluminum main body 1 and sheet-like fins 3. The aluminum main body 1 has heat exchange medium passages 2 that allow heat exchange medium to circulate.

The aluminum main body 1 of the heat exchanger of this embodiment has four circular passages of the same size, which are heat exchange medium passages 2. The cross-section of the heat exchange medium passages 2 can be in a shape of triangle, rectangle, quadrangle, or polygon, and preferably round or rectangle. As the round shaped cross-section has the smallest flow resistance, and the rectangular-shaped cross-section has the largest area within an aluminum main body 1 of a certain size. Moreover, since the aluminum main body 1 is molded by extrusion or stretching. In theory, it is not difficult to form heat exchange medium passages with a cross-section of any shape. However, the shape of the cross-section, the size, and the number of the heat exchange medium passages are generally determined by the force of the flow resistance of the heat exchange medium and the heat exchange amount.

In this embodiment, the cross-section of the main body 1 is rectangular or trapezoidal shaped. A row of fins 3 are respectively disposed on the upper and lower surfaces of the main body 1. Each of the fins 3 is rectangular shaped and evenly arranged on the upper and lower surfaces of the main body 1. The shape and the size of the fins 3, as well as the thickness, height, and the spacing therebetween, can be adjusted according to the requirements of heat exchange. If the heat exchange amount is great, the heat dissipation area must be enlarged by means of increasing the height of the fins 3 and decreasing the spacing between the fins 3. But, the wind resistance may be increased. Usually, a balance is found to meet the requirements. According to experience, if the wind speed is below 2.5 m/s, the spacing between the fins 3 remains 2.0-3.0 mm. If the wind speed is above 2.5 m/s, the spacing between the fins 3 remains 1.0-2.0 mm.

At first, the heat exchanger of this embodiment is a strip-shaped aluminum profile, and is still strip-shaped after the fins 3 are formed thereon (as shown in FIG. 2). Thereafter, the heat exchanger is bent several times into any desired shape according to requirements. For example, the heat exchanger is bent into the shape of “S”, “C”, or helix, so as to enhance the heat exchange effect without increasing the length of the product. In this embodiment, an “S” shaped heat exchanger 200 is formed as shown in FIG. 3, and a “C” shaped heat exchanger 300 is formed as shown in FIG. 8.

In this embodiment, the heat exchange medium passage 2 in the main body may be one, or two, three, or even more arranged in parallel according to the requirements of heat exchange.

As the main body is generally an aluminum profile molded by stretching (or extrusion), the heat exchanger of this embodiment is formed through the following processes. First, a mould is designed according to the requirements, and an aluminum profile with an appropriate cross-section is formed through stretching or extrusion. Heat exchange medium passages 2 that allow heat exchange medium to circulate are formed inside the aluminum profile. In this embodiment, four round heat exchange medium passages 2 of the same diameter are formed. Moreover, at least one external surface of the aluminum profile is designed to be a surface for the fins 3 to be processed thereon. In this embodiment, two opposite wider surfaces of the aluminum profile are designed into the surfaces for the fins 3 to be processed thereon. A plurality of fins 3 will be formed thereon later.

In the method of fabricating the heat exchanger according to this embodiment, the skiving process is adopted for fabricating the heat sink, and the fabricating method includes the following steps.

A1. The aluminum main body 1 is fabricated. An aluminum tube having heat exchange medium passages 2 that allow the heat exchange medium to circulate is formed through stretching or extrusion. The shape of the cross-section and the number of the heat exchange medium passages 2 in the main body 1 are determined according to the size of the heat exchanger, the requirement of heat exchange capacity, and the flow rate and resistance of the heat exchange medium. The heat exchange medium passages 2 may be designed into a plurality of passages with round, rectangular, or other different shaped cross-section.

B1. The heat sink is fabricated. The fins 3 are shaped through skiving on the external surface of the aluminum tube formed in Step A1.

According to the above fabrication process, the fins 3 are formed piece by piece or at a batch on the two processing surfaces of the aluminum main body 1 (for example, aluminum tube) by a skiving lathe, so the fins 3 and the main body 1 of the heat exchanger are a whole body, instead of being bonded by welding, expansion, or riveting, and even by using any adhesives. Therefore, no extra combined thermal resistance exists between the fins and the main body, thus enhancing the overall heat exchange efficiency of the heat exchanger. Meanwhile, the skiving process can greatly maintain the consistency of the fins 3, thus facilitating automatic production, and improving the processing efficiency while reducing the processing cost.

In this embodiment, the fins 3 are relieved piece by piece or at a batch. A batch of fins 3 instead of one piece of fin 3 can be relieved within an operating cycle by the following two methods. In one method, several main bodies to be relieved are fixed in parallel, and a skiving cutter that matches the width of the main bodies to be relieved is selected. The driving force of the skiving cutter is adjusted, so as to relieve multiple fins 3 in an operating cycle. That is to say, a piece of the fin 3 is relieved on each main body to be relieved, thus greatly enhancing the skiving efficiency. In another method, there are several processing surfaces to be relieved on the main body 1 to be relieved. Similarly, a proper skiving cutter is selected and the driving force of the skiving cutter is adjusted, so as to relieve a batch of fins 3 in an operating cycle. That is to say, one piece of the fin 3 is relieved on each processing surface. Definitely, the processing surfaces to be processed must meet certain requirements, for example, arranged in parallel and coplanar.

C1. The fins are pushed. The fins 3 are pushed to form a certain angle with respect to the surface of the main body 1. If the angle between the newly relieved fins 3 and the main body 1 does not meet the requirement, a process of pushing the fins may be added to achieve the desired angle. Fins are pushed through a special equipment and process, and may also be carried out during the skiving process. In this embodiment, a push plate fixed at the front of the skiving cutter is adopted to push the fins relieved in the previous operating cycle during the skiving process. The angle of the push plate is designed to be adjustable, so as to push the fins to a desired angle.

D1. The heat exchanger with the fins 3 relieved thereon are bent into a desired shape. The heat exchanger with the fins relieved thereon generally is strip-shaped. As the aluminum material is bendable, the strip-shaped heat exchanger with the fins 3 relieved thereon is bent into any desired shape, for example, the shape of “C”, “S”, or helix according to the requirements.

Embodiment 2

As shown in FIG. 4, the difference between this embodiment and the first embodiment is described as follows. In order to facilitate the connection between the heat exchange medium passages 2 in the main body 1 and the external heat exchange media, tube joints 4 are disposed at both ends of the heat exchanger, and the assembly thereof is shown in FIG. 5. The tube joints 4 may be screwed into the main body 1, or may be connected to the main body 1 through common methods like welding.

Embodiment 3

As shown in FIG. 6, in this embodiment, based on the second embodiment, a supporting plate 5 is disposed on one side of the heat exchanger. The supporting plate 5 is added, such that the heat exchanger may be mounted and fixed thereon conveniently, and the overall mounting size of the heat exchanger is ensured.

FIG. 7 is a schematic three-dimensional structural view of a heat exchanger with tube joints 4 and supporting plates 5. The difference between FIG. 7 and FIG. 6 is that the supporting plates 5 are two pieces of supporting plates of another structure. The two supporting plates 5 are disposed on both ends of the heat exchanger, such that the heat exchanger can be mounted and fixed thereon easily, and the overall mounting size of the heat exchanger can be ensured. The overall effect of the heat exchanger is also enhanced as the fins 3 at the center of the heat exchanger are not shielded.

Embodiment 4

As shown in FIG. 7, for the heat exchanger of this embodiment, after the fins 3 are relieved, the strip-shaped heat exchanger is bent into the shape of “C” as shown in FIG. 7 according to the requirement, so as to enhance its flexibility. Definitely, the heat exchanger may be bent into other different shapes according to requirements. In this embodiment, tube joints 4 are also disposed at both sides of the heat exchanger, so as to facilitate the connection to the external heat exchange medium passage.

In the present invention, as the heat exchange fins and the heat exchange medium passages are integrally formed, the copper tubes are omitted. Since the copper tubes take a large proportion in the cost of a conventional heat exchanger, the present invention can reduce the cost of raw materials. Besides, the aluminum tube that forms the main body is formed by extrusion, which enlarges and completely seals the heat exchange medium passages, thus avoiding the severe problem of the leakage of heat exchange medium in the conventional heat exchanger. Compared with the prior art, as the copper tubes are replaced by the integral structure, the process of fitting the fins and then expanding the tubes is avoided, and as the fins and the main body of the heat exchanger are a whole body, the heat exchange efficiency is enhanced and the process is simplified. Further, the heat exchanger can be bent into any desired shape after the fins are relieved. Thus, compared with the prior art in which several copper tubes are welded in order to form a desired shape, the present invention does not have any welding seam or welding spot, thereby avoiding the fatal defect of the leakage of the condensing agent in the conventional heat exchanger.

The heat exchanger provided by the present invention can be widely applied, not only to the conventional products like refrigerators and air-conditioners, but also to large-scale central air-conditioners with water-cooling media and water tank heat exchangers used in auto industry.

Though the present invention has been disclosed above by the preferred embodiments, they are not intended to limit the present invention. Those of ordinary skill in the art can make some modifications and variations without departing from the spirit and scope of the present invention. Therefore, the protecting range of the present invention falls in the appended claims.

Claims

1. A heat exchanger, comprising:

an aluminum main body having heat exchange medium passages that allow a heat exchange medium to circulate; and

fins for heat exchange which extending outward from a surface of said aluminum main body.

2. The heat exchanger of claim 1, wherein the fins are of a sheet structure and formed through skiving technics.

3. The heat exchanger of claim 2, wherein a thickness, height, and spacing of the fins are determined by a quantity of heat exchange and a force of wind resistance.

4. The heat exchanger of claim 2, wherein the heat exchanger is bent into a shape of “S”, “C”, or helix.

5. The heat exchanger of claim 4, wherein a transverse cross-section of said aluminum main body is rectangular or trapezoidal shaped, and said fins are disposed on two opposite sides of said aluminum main body.

6. The heat exchanger of claim 5, wherein said heat exchanger further comprises a supporting plate on which said heat exchanger is mounted and fixed, and tube joints disposing at both ends of said main body for connecting the heat exchange medium passages inside said main body and an external heat exchange medium piping.

7. The heat exchanger of claim 6, wherein the transverse cross-section of said heat exchange medium passages is in a shape of round, triangle, quadrangle, or polygon.

8. The heat exchanger of claim 7, wherein plurality of heat exchange medium passages disposing in said main body.

9. A method of fabricating the heat exchanger, comprising the following step:

A1. fabricating a aluminum main body: forming the aluminum main body having heat exchange medium passages that allow a heat exchange medium to circulate through stretching or extrusion;

B1. fabricating the heat sink: shaping fins through skiving technics on an external surface of said aluminum main body formed in Step A1.

10. The method of claim 9, further comprising the following steps after Step B1:

C1. pushing said fins: adjusting said fins to form a certain angle with respect to a surface of said main body;

D1. bending said heat exchanger with fins relieved thereon into a desired shape.