JP2009236470A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger capable of obtaining high heat exchanging efficiency. <P>SOLUTION: The heat exchanger includes a tube 32 for distributing internal fluid, fins 31 thermally connected to the tube 32, provided along an exterior fluid distribution direction AA distributed on the outside of the tube 32, and aligned in parallel in an extension direction BB of the tube 32 at a fin pitch Fp, and a plurality of louvers 313 formed on the fins 31 inclined at an inclination angle Lθ with respect to the distribution direction AA and aligned in parallel in the distribution direction AA at a louver pitch Lp. The relation of the fin pitch Fp and the louver pitch Lp satisfies Lp≤0.7×Fp, and the louver pitch Lp is 0.5(mm)≤Lp≤0.75(mm). The louver pitch Lp, the inclination angle Lθ, and a thickness t of the louver 313 satisfy the relation of 0.164×exp(0.3229×Lp)≤Lp×sinLθ-t≤0.3381×exp(-0.1069×Lp). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat exchanger including a fin thermally connected to a tube and a louver formed on the fin.

  Conventionally, a tube through which an internal fluid flows, a fin that is thermally connected to the tube and increases the heat transfer area between the internal fluid and the external fluid, and formed by cutting and raising the fin from the fin to the external fluid by the leading edge effect There is a heat exchanger having a louver that increases the heat transfer rate of the heat exchanger. In such a heat exchanger, when the flow velocity of the external fluid at the louver tip is reduced due to the influence of the wake of the front louver, the leading edge effect is lowered and the heat exchange performance may be lowered. In Patent Document 1, in order to suppress the decrease in the leading edge effect and improve the heat exchange performance, the louver inclination angle Lθ with respect to the flow direction of the external fluid, the fin pitch Fp, and the louver pitch Lp are expressed by the following equation (1). It is set to satisfy the relationship.

0.2 <Lp / Fp × tanLθ <0.45 (1)
JP-A-2-238297

  In recent years, the louver pitch Lp tends to be finer, while the fin pitch Fp does not tend to be so fine. In such a recent heat exchanger, it has been found that even if fins and louvers are formed so as to satisfy the relationship of Expression (1), the heat exchange performance cannot always be improved.

  For example, in the case of a heat exchanger in which the fin pitch Fp is 1.25 mm and the louver pitch Lp is 0.7 mm, if the louver inclination angle Lθ is in the range of 19.7 ° <Lθ <38.8 °, the fin pitch Fp The louver pitch Lp and the inclination angle Lθ satisfy the relationship of the expression (1).

  However, when the inventors of the present application confirmed by experiment and analysis, even if the inclination angle Lθ is in the above range, the heat exchange performance of the heat exchanger does not necessarily improve, and the range of the inclination angle Lθ in which high heat exchange performance is obtained. Was found to be even narrower than the above range.

  An object of the present invention is to provide a heat exchanger capable of obtaining high heat exchange performance.

  In order to achieve the above object, the present invention employs the following technical means.

According to the first aspect of the present invention, the tube (32) through which the internal fluid flows and the flow direction (AA) of the external fluid that is thermally connected to the tube (32) and flows outside the tube (32) are provided. A fin (31) provided in parallel with the extending direction (BB) of the tube (32) at a predetermined fin pitch Fp and inclined at a predetermined inclination angle Lθ with respect to the flow direction (AA). And a plurality of louvers (313) parallel to the flow direction (AA) at a predetermined louver pitch Lp, the fin pitch Fp and the louver pitch Lp being in a relationship of Lp ≦ 0.7 × Fp, and the louver pitch Lp being The heat exchanger is 0.5 (mm) ≦ Lp ≦ 0.75 (mm), and the louver pitch Lp, the inclination angle Lθ, and the plate thickness t of the louver (313) are:
0.164 × exp (0.3229 × Lp) ≦ Lp × sinLθ−t
≦ 0.3381 × exp (−0.1069 × Lp)
It is a heat exchanger characterized by satisfying this relationship.

  Thereby, even if it is a heat exchanger with which louver pitch Lp was densified with respect to fin pitch Fp, high heat exchange performance is obtained.

  The invention according to claim 2 is characterized in that the fin (31) has a corrugated shape. Thereby, since it becomes easy to arrange a fin (31) in the extending | stretching direction (BB) of a tube (32) with the fin pitch Fp, the manufacturing process of a heat exchanger can be simplified.

  As in the third aspect of the invention, the fin (31) may have a flat plate shape.

  The invention according to claim 4 is along the tube (32) through which the internal fluid flows and the flow direction (AA) of the external fluid that is thermally connected to the tube (32) and flows outside the tube (32). A fin (31) provided in parallel with the extending direction (BB) of the tube (32) at a predetermined fin pitch Fp and inclined at a predetermined inclination angle Lθ with respect to the flow direction (AA). And a plurality of louvers (313) parallel to the flow direction (AA) at a predetermined louver pitch Lp, the fin pitch Fp and the louver pitch Lp being in a relationship of Lp ≦ 0.7 × Fp, and the louver pitch Lp being The heat exchanger is 0.5 (mm) ≦ Lp ≦ 0.75 (mm), and the louver pitch Lp, the inclination angle Lθ, and the plate thickness t of the louver (313) are 0.2 (mm) ≦ Lp × sinLθ- It is a heat exchanger characterized by satisfying a relationship of t ≦ 0.3 (mm).

  Thereby, even if it is a heat exchanger with which louver pitch Lp was densified with respect to fin pitch Fp, high heat exchange performance is obtained.

  In addition, the code | symbol in the bracket | parenthesis of each said means has shown an example of the corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an external perspective view showing a configuration of a radiator 1 as a heat exchanger in the present embodiment. FIG. 2 is a front view showing only the fins 31 disposed between the tubes 32 of the radiator 1. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a schematic diagram showing the arrangement relationship of the louvers 313 in adjacent fins 31. The heat exchanger of this embodiment is used in a cooling water circuit that circulates engine cooling water (internal fluid) for cooling a water-cooled engine mounted on a vehicle, and the engine is exchanged with heat (external fluid). This is a radiator for cooling the cooling water.

  As shown in FIG. 1, the radiator 1 is a so-called downflow type (longitudinal flow type) in which engine cooling water flows from above to below in a tube 32 extending in a substantially vertical direction. The radiator 1 includes a core portion 30, an upper tank 10, and a lower tank 20 as a basic configuration.

  The core unit 30 includes fins 31, tubes 32, side plates (inserts) 33 and a core plate 34. These constituent members are formed of an aluminum material or an aluminum alloy material that is lightweight and excellent in corrosion resistance, and are integrally joined by brazing. The fins 31 formed into a waveform from the thin strip material and the tubes 32 having a flat cross-sectional shape are alternately stacked in a substantially horizontal direction. A side plate 33 as a reinforcing member is provided further outside the outermost fin 31. Both end portions of each tube 32 in the extending direction (BB direction) are fitted in tube holes formed in the core plate 34, respectively.

  The upper tank 10 and the lower tank 20 are formed from a high-strength resin material having excellent heat resistance, such as a polyamide material containing glass fibers. Both tanks 10 and 20 have a substantially U-shaped cross-sectional shape, and are formed in a container shape having an opening on the side facing the core plate 34. Both tanks 10 and 20 are mechanically joined to the core portion 30 by caulking. A sealing member (packing) (not shown) is interposed at a joint portion between the tanks 10 and 20 and the core plate 34.

  The upper tank 10 is integrally formed with an inlet pipe 11 projecting across the longitudinal direction, a water injection port 17 for injecting engine cooling water into the interior, and a mounting portion 18 for mounting the radiator 1 to the vehicle. Is formed. The lower tank 20 is integrally formed with an outlet pipe 21 and a mounting portion 22. An engine hose (not shown) is inserted into the inlet pipe 11 and the outlet pipe 21. Engine coolant from the vehicle engine flows into the upper tank 10 and the core part 30 from the inlet pipe 11 and is cooled by heat exchange with air flowing in the AA direction in the core part 30. The cooled engine coolant flows out from the outlet pipe 21 of the lower tank 20 and returns to the engine again.

  As shown in FIG. 2, the fin 31 is a corrugated fin, and a plurality of planar portions 312 formed in a planar shape so as to be substantially parallel to the AA direction and the adjacent planar portions 312 are curvedly connected to each other. And a curved portion 311 joined to a side surface of the tube 32 (not shown in FIG. 2). As shown in FIGS. 3 and 4, the flat portions 312 of the fins 31 are provided in parallel in the BB direction at a predetermined fin pitch (average fin pitch) Fp.

  A plurality of louvers 313 that are arranged in parallel in the AA direction at a predetermined louver pitch Lp are formed on each plane portion 312. The plurality of louvers 313 are turned at the central portion in the AA direction of the flat portion 312 and are inclined in the opposite directions on the upstream side (left side in FIG. 3) and the downstream side (right side in FIG. 3). Each louver 313 is inclined at substantially the same inclination angle Lθ with respect to the AA direction. Most of the louvers 313 are so-called double-cut louvers in which both end portions in the AA direction are cut and raised on opposite sides of the plane portion 312. The louvers 313 located at both ends in the AA direction are so-called one-side louvers in which only one end portion is cut and raised.

  In the radiator 1 of the present embodiment, the louver pitch Lp is finer than the fin pitch Fp, and the louver pitch Lp and the fin pitch Fp have a relationship of Lp ≦ 0.7 × Fp. Further, the louver pitch Lp is set to 0.5 mm or more, which is considered to be a cutting limit of the louver, which is narrower than 0.75 mm, which is narrower than the louver pitch (0.8 mm) in the conventional general heat exchanger. (0.5 (mm) ≦ Lp ≦ 0.75 (mm)).

  Here, in the heat exchanger in which the louver pitch Lp is finer than the fin pitch Fp, even if the fin 31 and the louver 313 are formed so as to satisfy the relationship of the expression (1), the heat exchange performance is not necessarily improved. explain.

  First, the first reason will be described. In Formula (1), the range of the clearance ratio (Lp / Fp × tanLθ) calculated based on the fin pitch Fp, the louver pitch Lp, and the inclination angle Lθ is defined. However, when the louver pitch Lp is made finer with respect to the fin pitch Fp and the ratio of the louver pitch Lp to the fin pitch Fp (Lp / Fp) becomes smaller, the range of the inclination angle Lθ satisfying the expression (1) becomes larger than necessary. End up. Therefore, the range of the inclination angle Lθ actually required for improving the heat exchange performance cannot be defined.

  Next, the second reason will be described with reference to FIG. FIG. 5 is a diagram corresponding to FIG. 4, and is a schematic diagram showing an arrangement relationship of louvers 413 in a conventional radiator having a relatively large louver pitch Lp. As shown in FIG. 5, when the louver pitch Lp is relatively larger than the fin pitch Fp (Lp≈Fp), the distance Ld between the upstream louver 413a and the downstream louver 413b is relatively short. Therefore, the influence of the louver 413a is relatively large in the vicinity of the front edge portion 414 of the louver 413b. For this reason, depending on the arrangement relationship of the louvers 413a and 413b, the flow rate of the external fluid (air) at the front edge portion 414 of the louver 413b is lowered due to the influence of the wake of the louver 413a, and the leading edge effect is lowered. Therefore, it is necessary to suppress the deterioration of the leading edge effect by forming the fins and the louvers so as to satisfy the relationship of the expression (1).

  On the other hand, in the radiator 1 of the present embodiment in which the louver pitch Lp is finer than the fin pitch Fp, as shown in FIG. 4, the distance Ld between the upstream louver 313a and the downstream louver 313b is compared. Therefore, the influence of the louver 313a is not so much in the vicinity of the front edge 314 of the louver 313b. For this reason, regardless of the arrangement relationship of the louvers 313a and 313b, the flow velocity distribution at the front edge portion 314 of the louver 313b is made uniform, so that the front edge effect is not significantly reduced. That is, even if the relationship of the formula (1) for suppressing the decrease in the leading edge effect is satisfied, the heat exchange performance is not always improved.

  For these two reasons, in a radiator in which the louver pitch Lp is finer than the fin pitch Fp, even if the fin 31 and the louver 313 are formed so as to satisfy the relationship of the expression (1), the heat exchange performance is not necessarily improved. It is thought not to. Therefore, the inventor of the present application examined a new index that replaces the conventional index.

  If the fin pitch Fp is fixed, the heat exchange performance of the heat exchanger is positively correlated with the flow rate of the external fluid passing between the louvers 313. The flow rate of the external fluid passing between the louvers 313 depends on the louver clearance Lc (Lc = Lp × sinLθ−t) obtained based on the louver pitch Lp, the inclination angle Lθ, and the plate thickness t of the louver 313 (fin 31). Change.

  FIG. 6 is a schematic diagram showing an arrangement relationship of the louvers 313 when the louver clearance Lc is relatively small. As shown in FIG. 6, in the heat exchanger in which the louver pitch Lp is made fine, when the louver clearance Lc is reduced, the influence of the velocity boundary layer 315 formed near the surface of the louver 313 cannot be ignored. When the thickness of the boundary layer 315 is δ, the substantial gap Lc0 between the louvers 313 through which the external fluid passes is the difference between the louver clearance Lc and the sum 2δ of the thicknesses of the boundary layers 315 on both sides (Lc0 = Lc− 2δ). That is, the substantial gap Lc0 between the louvers 313 is further narrower than the louver clearance Lc. Therefore, when the louver clearance Lc is narrowed, the flow rate of the external fluid passing between the louvers 313 is significantly reduced, and most of the external fluid passes between the fins 31. Therefore, the heat exchange performance of the heat exchanger is degraded.

  FIG. 7 is a schematic diagram showing an arrangement relationship of the louvers 313 when the louver clearance Lc is relatively large. As shown in FIG. 7, in order to increase the louver clearance Lc in a heat exchanger with a finer louver pitch Lp, it is necessary to increase the inclination angle Lθ of the louver 313. However, when the inclination angle Lθ is increased, the pressure loss increases because the flow path of the external fluid is greatly bent. Therefore, the flow rate of the external fluid that passes between the fins 312 decreases, and the heat exchange performance of the heat exchanger decreases.

  As described above, in the heat exchanger in which the louver pitch Lp is refined, the heat exchange performance is deteriorated even if the louver clearance Lc is too small or too large. Therefore, it can be seen that the louver clearance Lc has a range in which high heat exchange performance can be obtained.

  In addition, as already described, since the heat exchanger having a finer louver pitch Lp has little influence on the performance of the fin pitch Fp, the range of the louver clearance Lc for obtaining high heat exchange performance depends on the fin pitch Fp. do not do.

  This inventor calculated | required the range of the louver clearance Lc in which high heat exchange performance is obtained based on an experimental result. FIG. 8 is a graph showing the relationship between louver clearance Lc and heat exchange performance in four types of radiators having different louver pitches Lp. The horizontal axis of the graph represents the louver clearance Lc (mm), and the vertical axis represents the heat exchange performance as a performance ratio (%). Curve C0 in the graph shows the relationship between louver clearance Lc and heat exchange performance in a conventional radiator having a louver pitch Lp of 0.8 mm, and curves C1 to C3 show louver pitch Lp of 0.75 mm, 0.7 mm, and The relationship between the louver clearance Lc and the heat exchange performance in a radiator of 0.5 mm is shown. Here, all the radiators have a fin pitch Fp of 1.25 mm and satisfy the relationship of Lp ≦ 0.7 × Fp. The plate thickness t of the louver 313 was 0.05 mm, and the width of the fin 31 in the AA direction was 16 mm. The performance ratio was based on the highest heat exchange performance (100%) obtained with a conventional radiator (Lp = 0.8 (mm)).

  As shown in FIG. 8, although the heat exchange performance tends to be higher as the louver pitch Lp is narrower, it has been found that the range of the louver clearance Lc with which high heat exchange performance is obtained is not significantly changed in any radiator. . In particular, in a radiator having a louver pitch Lp of 0.5 mm or more and 0.75 mm or less, the louver clearance Lc is represented by a line L1 (Lc = 0.164 × exp (0.3229 × Lp)) and a line L2 (0.3381 × exp). It was confirmed that a performance ratio of at least 100% or more can be obtained within the range defined by (−0.1069 × Lp). In addition, it was confirmed that high heat exchange performance was obtained with any radiator as long as the louver clearance Lc was in the range of 0.2 mm to 0.3 mm. Furthermore, if the louver clearance Lc is in the range of 0.25 mm or more and 0.26 mm or less, it was confirmed that the highest heat exchange performance was obtained in each radiator.

  FIG. 9A is a graph showing the relationship between the louver clearance Lc and the heat exchange performance in a radiator having a fin pitch Fp of 1.25 mm and a louver pitch Lp of 0.7 mm. FIG. 9B is a graph showing the relationship between the louver clearance Lc and the heat exchange performance in a radiator having a fin pitch Fp of 1.75 mm and a louver pitch Lp of 0.7 mm. The horizontal and vertical axes of both graphs are the same as in FIG. 8, and the criteria for the performance ratio are the same as in FIG. As shown in FIGS. 9 (a) and 9 (b), it was confirmed that even if the fin pitch Fp is different, the range of the louver clearance Lc with which high heat exchange performance can be obtained does not change much. This is considered to be due to the second reason described above.

  Therefore, in the radiator in which the louver pitch Lp is in the relationship of Lp ≦ 0.7 × Fp and the louver pitch Lp is 0.5 mm or more and 0.75 mm or less, the louver clearance Lc satisfies the following expression (2). If it does, it turned out that it is not dependent on fin pitch Fp and the heat exchange performance more than before is obtained.

0.164 × exp (0.3229 × Lp) ≦ Lc
≦ 0.3381 × exp (−0.1069 × Lp)
However, Lc = Lp × sinLθ−t (2)
Here, the above conditions are those for the radiator 1 with the fin 31 having a width of 16 mm in the AA direction. However, the inventors of the present application have studied that if the radiator has a width of the fin 31 of 30 mm or less, the formula (2 ), It has been found that the heat exchange performance higher than that of the conventional one can be obtained.

  As described above, according to the present embodiment, high heat exchange performance can be obtained even with the radiator 1 in which the louver pitch Lp is finer than the fin pitch Fp.

  In the present embodiment, the radiator 1 has a configuration in which flat tubes 32 and corrugated fins 31 are laminated. As a result, by joining the tubes 32 and the fins 31, the fins 31 (planar portions 312) can be easily arranged in parallel in the BB direction with a substantially constant fin pitch Fp, thereby simplifying the manufacturing process of the radiator 1. it can.

(Other embodiments)
In the said embodiment, although the heat exchanger provided with the corrugated fin 31 was mentioned as an example, it is applicable also to the heat exchanger provided with the flat plate-shaped plate fin.

  Moreover, in the said embodiment, although the heat exchanger provided with the core part 30 made from aluminum or aluminum alloy was mentioned as an example, it applies also to the heat exchanger with which the core part was formed with other materials, such as copper and stainless steel. it can.

  Furthermore, in the said embodiment, although the downflow type heat exchanger was mentioned as an example, it is applicable also to a crossflow type heat exchanger.

It is an external appearance perspective view which shows the structure of a radiator as a heat exchanger in 1st Embodiment. It is a front view which shows only the fin arrange | positioned between the tubes of a radiator. It is the III-III sectional view taken on the line of FIG. It is a schematic diagram which shows the arrangement | positioning relationship of the louver in an adjacent fin. FIG. 6 is a schematic diagram showing a louver arrangement relationship in a conventional radiator having a relatively large louver pitch Lp. It is a schematic diagram which shows the arrangement | positioning relationship of a louver in case the louver clearance Lc is comparatively small. It is a schematic diagram which shows the arrangement | positioning relationship of a louver in case the louver clearance Lc is comparatively large. It is a graph which shows the relationship between the louver clearance Lc and the heat exchange performance in the radiator from which louver pitch Lp differs. It is a graph which shows the relationship between the louver clearance Lc and heat exchange performance in the radiator from which fin pitch Fp differs.

Explanation of symbols

1 Radiator (heat exchanger)
30 Core part 31 Fin 32 Tubes 313, 313a, 313b Louver 314 Front edge part 315 Boundary layer

Claims (4)

A tube (32) for circulating an internal fluid;
An extension direction of the tube (32) at a predetermined fin pitch Fp provided along a flow direction (AA) of an external fluid that is thermally connected to the tube (32) and flows outside the tube (32). A fin (31) in parallel with (BB);
A plurality of louvers (313) formed on the fin (31) and inclined at a predetermined inclination angle Lθ with respect to the flow direction (AA), and arranged in parallel with the flow direction (AA) at a predetermined louver pitch Lp. ,
The fin pitch Fp and the louver pitch Lp are in a relationship of Lp ≦ 0.7 × Fp, and the louver pitch Lp is 0.5 (mm) ≦ Lp ≦ 0.75 (mm),
The louver pitch Lp, the inclination angle Lθ, and the plate thickness t of the louver (313) are:
0.164 × exp (0.3229 × Lp) ≦ Lp × sinLθ−t
≦ 0.3381 × exp (−0.1069 × Lp)
A heat exchanger characterized by satisfying the relationship of   The heat exchanger according to claim 1, wherein the fin (31) has a corrugated shape.   The heat exchanger according to claim 1, wherein the fin (31) has a flat plate shape. A tube (32) for circulating an internal fluid;
An extension direction of the tube (32) at a predetermined fin pitch Fp provided along a flow direction (AA) of an external fluid that is thermally connected to the tube (32) and flows outside the tube (32). A fin (31) in parallel with (BB);
A plurality of louvers (313) formed on the fin (31) and inclined at a predetermined inclination angle Lθ with respect to the flow direction (AA), and arranged in parallel with the flow direction (AA) at a predetermined louver pitch Lp. ,
The fin pitch Fp and the louver pitch Lp are in a relationship of Lp ≦ 0.7 × Fp, and the louver pitch Lp is 0.5 (mm) ≦ Lp ≦ 0.75 (mm),
The louver pitch Lp, the inclination angle Lθ, and the plate thickness t of the louver (313) satisfy a relationship of 0.2 (mm) ≦ Lp × sin Lθ−t ≦ 0.3 (mm). vessel.

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