Heat Exchanger

Abstract

 Disclosed is a heat exchanger having a corrugated fin (5) on which a plurality of louvers (12, 14) are arranged in an air-flow direction (D), wherein a length A in the air-flow direction (D) of each of a windward flat portion (11) and a leeward flat portion (15) is set in a range of 0.5 mm to 1.1 mm, a length B of an intermediate flat portion (13) is set in a range of 0.5 mm to 1.7 mm, an inclination angle of each of the windward louvers (12) and the leeward louvers (14) is set in a range of 23 degrees to 26 degrees, and a length of a chord (5b) of a circular arc portion forming a turning part (5a) of the corrugated fin (5) is set at a length of 1.2 mm or more. By optimizing all of these factors, the efficiency for heat exchange of the heat exchanger may be greatly improved.

Description

[0001] The present invention relates to a heat exchanger having a corrugated fin on which a plurality of louvers are arranged in an air-flow direction, and specifically, to a heat exchanger suitable as a heat exchanger used in a refrigeration system of an air conditioning system for a vehicle.

[0002] In a conventional heat exchanger, for example, a stacking type heat exchanger in which tubes and corrugated fins are stacked alternately, a structure is known wherein a plurality of louvers are arranged in an air-flow direction on each corrugated fin, thereby improving the efficiency for heat exchange (for example, Japanese Utility Model Laid-Open 55-167087).

[0003] In such a heat exchanger, a structure is also known wherein a windward flat portion, a group of windward louvers each inclined relative to the air-flow direction, an intermediate flat portion, a group of leeward louvers each inclined in a direction opposite to the inclined direction of the windward louvers, and a leeward flat portion are formed on the corrugated fin in this order from the upstream side of the air-flow direction. Further, each louver is usually formed by cutting and raising a part of the corrugated fin.

[0004] In such a heat exchanger, the efficiency for heat exchange greatly changes by the shape of the corrugated fin, and the positions, the inclination angles, etc. of the group of windward louvers and the group of leeward louvers. For example, the efficiency for heat exchange changes by the inclination angles of the windward louvers and the leeward louvers, the lengths in the air-flow direction of the windward flat portion and the leeward flat portion, etc.

[0005] Although a proposal for optimizing the inclination angles and shapes of the windward louvers and the leeward louvers has been done (for example, JP-A-2005-140454), there is a room for further improvement.

[0006] Accordingly, it would be desirable to provide a heat exchanger which can further optimize a shape of a corrugated fin in the heat exchanger, an inclination angle of louvers provided on the corrugated fin, etc., thereby further improving the efficiency for heat exchange of the heat exchanger.

[0007] A heat exchanger according to the present invention has a corrugated fin on which a plurality of louvers are arranged in an air-flow direction, and is characterized in that a windward flat portion, a group of windward louvers each inclined relative to the air-flow direction, an intermediate flat portion, a group of leeward louvers each inclined in a direction opposite to the inclined direction of the windward louvers, and a leeward flat portion are formed on the corrugated fin in this order from the upstream side of the air-flow direction, and

(a) a length in the air-flow direction of each of the windward flat portion and the leeward flat portion is set in a range of 0.5 mm to 1.1 mm,

(b) a length in the air-flow direction of the intermediate flat portion is set in a range of 0.5 mm to 1.7 mm,

(c) an inclination angle of each of the windward louvers and the leeward louvers relative to the air-flow direction is set in a range of 23 degrees to 26 degrees, and

(d) a length of a chord of a circular arc portion forming a turning part of the corrugated fin is set at a length of 1.2 mm or more.

[0008] In a more desirable embodiment of this heat exchanger, it is preferred that the length in the air-flow direction of each of the windward flat portion and the leeward flat portion is set in a range of 0.7 mm to 0.9 mm. Further, it is preferred that the length in the air-flow direction of the intermediate flat portion is set in a range of 0.9 mm to 1.3 mm. Further, it is preferred that the inclination angle of each of the windward louvers and the leeward louvers relative to the air-flow direction is set in a range of 23.5 degrees to 25 degrees, and in a most desirable embodiment, it is set at 24 degrees.

[0009] Further, the length of the chord of the circular arc portion forming the turning part of the corrugated fin is set at a length of 1.2 mm or more. Although a dead air area retaining passing air or forming a vortex flow is likely to be formed near the turning part of the corrugated fin, if the length of the chord of the circular arc portion forming the turning part of the corrugated fin is less than 1.2 mm, the air-flow resistance may increase and the dead air area may increase.

[0010] In the heat exchanger according to the present invention, it is preferred that each of the group of windward louvers and the group of leeward louvers is formed by cutting and raising a part of the corrugated fin.

[0011] Although the type of the heat exchanger according to the present invention is not particularly limited, for example, the heat exchanger is formed as a stacking type heat exchanger in which tubes and corrugated fins are stacked alternately.

[0012] Further, the heat exchanger according to the present invention is suitable as a heat exchanger provided in a refrigeration system of an air conditioning system for a vehicle. In particular, the heat exchanger according to the present invention is suitable as a heat exchanger for heat radiation.

[0013] In the heat exchanger according to the present invention, because the lengths of the windward flat portion and the leeward flat portion, the length of the intermediate flat portion, the inclination angles of the windward louvers and the leeward louvers, and the length of the chord of the circular arc portion forming the turning part of the corrugated fin, are all optimized, the efficiency for heat exchange of the heat exchanger may be greatly improved.

[0014] Further features and advantages of the present invention will be understood from the following detailed description of the preferred embodiments of the present invention with reference to the accompanying figures, of which:

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

Fig. 2 is an enlarged sectional view of a louver portion provided on a corrugated fin of the heat exchanger depicted in Fig. 1.

Fig. 3 is an enlarged elevational view of portion C of the heat exchanger depicted in Fig. 1.

Fig. 4 is a graph showing a relationship between a heat flux and an air-flow resistance and a length A of a windward flat portion and a leeward flat portion.

Fig. 5 is a graph showing a relationship between a heat flux and an air-flow resistance and a length B of an intermediate flat portion.

Fig. 6 is a graph showing a relationship between a heat flux and an air-flow resistance and an inclination angle of louvers.

Fig. 7 is a graph showing a relationship between a heat flux and an air-flow resistance and a length of a chord of a circular arc portion forming a turning part of a corrugated fin.

[0015] Hereinafter, the desirable embodiments of the heat exchanger according to the present invention will be explained referring to figures.

[0016] Fig. I depicts a heat exchanger according to an embodiment of the present invention. In this embodiment, the heat exchanger is formed as a stacking type heat exchanger 1 in which tubes 4 and corrugated fins 5 are stacked alternately. Heat exchanger 1 has a pair of headers 2 and 3, and a plurality of tubes 4 are disposed between headers 2 and 3. Corrugated fins 5 are disposed between adjacent tubes 4, on the uppermost tube 4 and under the lowermost tube 4, respectively. Side plates 6 are provided on the uppermost corrugated fin 5 and under the lowermost corrugated fin 5, respectively. An inlet pipe 7 is provided on one header 3, and an outlet pipe 8 is provided on the other header 2. In Fig. 1, the direction shown by arrow D is an air-flow direction.

[0017] As depicted in Fig. 2, on corrugated fin 5, a windward flat portion 11, a group of windward louvers 12 each inclined relative to air-flow direction D, an intermediate flat portion 13, a group of leeward louvers 14 each inclined in a direction opposite to the inclined direction of windward louvers 12, and a leeward flat portion 15 are formed in this order from the upstream side of air-flow direction D.

[0018] A length A in air-flow direction D of each of windward flat portion 11 and leeward flat portion 15 is set in a range of 0.5 mm to 1.1 mm, and in this embodiment, set within a range of 0.7 mm to 0.9 mm. A length B in air-flow direction D of intermediate flat portion 13 is set in a range of 0.5 mm to 1.7 mm, and in this embodiment, set within a range of 0.9 mm to 1.3 mm. An inclination angle α of each of windward louvers 12 and leeward louvers 14 relative to air-flow direction D is set in a range of 23 degrees to 26 degrees, and in this embodiment, set at 24 degrees.

[0019] Further, as depicted in Fig. 3, a length of a chord 5b of a circular arc portion forming a turning part 5a of corrugated fin 5 is set at a length of 1.2 mm or more.

Example 1:

[0020] The relationships between a heat flux (W/m²) and the length A (mm) in air-flow direction D of each of windward flat portion 11 and leeward flat portion 15 and between an air-flow resistance (Pa) and the length A were determined. The result is shown in Fig. 4. An optimum range of length A is a range in which the heat flux is great and the air-flow resistance is small. As is evident from Fig. 4, the optimum range of length A was 0.5 mm or more and 1.1 mm or less, preferably 0.7 mm or more and 0.9 mm or less.

Example 2:

[0021] The relationships between a heat flux (W/m²) and the length B (mm) in air-flow direction D of intermediate flat portion 13 and between an air-flow resistance (Pa) and the length B were determined. The result is shown in Fig. 5. An optimum range of length B is a range in which the heat flux is great and the air-flow resistance is small. As is evident from Fig. 5, the optimum range of length B was 0.5 mm or more and 1.7 mm or less, preferably 0.9 mm or more and 1.3 mm or less.

Example 3:

[0022] The relationships between a heat flux (W/m²) and the inclination angle α of each of windward louvers 12 and leeward louvers 14 relative to air-flow direction D and between an air-flow resistance (Pa) and the inclination angle α were determined. The result is shown in Fig. 6. An optimum range of inclination angle α is a range in which the heat flux is great and the air-flow resistance is small. As is evident from Fig. 6, the optimum range of inclination angle α was 23 degrees or more and 26 degrees or less, preferably 23.5 degrees or more and 25 degrees or less, and the most preferable inclination angle α was 24 degrees.

Example 4:

[0023] The relationships between a heat flux (W/m²) and the length (mm) of chord 5b of the circular arc portion forming turning part 5a of corrugated fin 5 and between an air-flow resistance (Pa) and the length of chord 5b were determined. The result is depicted in Fig. 7. As shown in Fig. 7, when the length of chord 5b was less than 1.2 mm, the heat flux decreased greatly and the air-flow resistance increased like a quadratic curve. Therefore, it is understood that the length of chord 5b is preferred to be 1.2 mm or more.

[0024] Thus, the optimum ranges of the respective factors in the present invention were all confirmed by the above-described experiments according to Examples 1 to 4.

[0025] The structure of the heat exchanger according to the present invention may be applied to a heat exchanger having a corrugated fin arranged with a plurality of louvers in an air-flow direction, and in particular, it is suitable as a heat exchanger provided in a refrigeration system of an air conditioning system for a vehicle.

Claims

1. A heat exchanger having a corrugated fin on which a plurality of louvers are arranged in an air-flow direction, characterized in that a windward flat portion, a group of windward louvers each inclined relative to said air-flow direction, an intermediate flat portion, a group of leeward louvers each inclined in a direction opposite to the inclined direction of said windward louvers, and a leeward flat portion are formed on said corrugated fin in this order from the upstream side of said air-flow direction, and

(a) a length in said air-flow direction of each of said windward flat portion and said leeward flat portion is set in a range of 0.5 mm to 1.1 mm,

(b) a length in said air-flow direction of said intermediate flat portion is set in a range of 0.5 mm to 1.7 mm,

(c) an inclination angle of each of said windward louvers and said leeward louvers relative to said air-flow direction is set in a range of 23 degrees to 26 degrees, and

(d) a length of a chord of a circular arc portion forming a turning part of said corrugated fin is set at a length of 1.2 mm or more.

2. The heat exchanger according to claim 1, wherein each of said group of windward louvers and said group of leeward louvers is formed by cutting and raising a part of said corrugated fin.

3. The heat exchanger according to claim 1 or 2, wherein said heat exchanger is formed as a stacking type heat exchanger in which tubes and corrugated fins are stacked alternately.

4. The heat exchanger according to any preceding claim, wherein said heat exchanger is a heat exchanger provided in a refrigeration system of an air conditioning system for a vehicle.

5. The heat exchanger according to any preceding claim, wherein said heat exchanger is a heat exchanger for heat radiation.

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