US20070193730A1

US20070193730A1 - Heat exchanger device

Info

Publication number: US20070193730A1
Application number: US11/714,523
Authority: US
Inventors: Tatsuo Ozaki
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2004-09-08
Filing date: 2007-03-06
Publication date: 2007-08-23
Also published as: GB0703282D0; CN101010555A; JP2006078035A; WO2006028253A1; DE112005002177T5; GB2431464A

Abstract

The heat transfer performance of a heat exchanger situated on the downstream side of airflow is improved by utilizing a turbulent flow in a heat exchanger situated on the upstream side of airflow.

At least on fins 12 of a heat exchanger 10 on the upstream side of airflow among a plurality of heat exchanger devices 10, 20 arranged in series in the airflow direction, collision walls 12 c cut and raised in an upright position as a turbulent flow forming means for stirring airflow are provided.

Description

CROSS REFERENCE TO ANY RELATED APPLICATIONS

This is continuation of PCT Application No. PCT/JP2005/016864, filed on Sep. 7, 2005. This application takes priority from Japanese patent Application No. 2004-260740 filed on Sep. 8, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a heat exchanger device in which a plurality of heat exchangers are arranged in series in the airflow direction, suitable as a heat exchanger device in which a refrigerant heat dissipater for vehicle air conditioning and a radiator for cooling vehicle engine are arranged in series.
2. Description of the Related Art
An attempt is made to improve the heat transfer rate of fins of a conventional heat exchanger by providing slit pieces constituting segments arranged in a staggered form with respect to an airflow and by providing a bent part by bending the upstream side of an airflow of the slit piece through about 90 degrees to stir the airflow and restrict the growth of a temperature boundary layer (for example, refer to patent document 1).
[Patent document 1] Japanese Unexamined Patent Publication (Kokai) No. 63-83591
By the way, in the invention described in patent document 1, the slit piece is formed by cutting and raising a portion of the thin plate-shaped fin and the bent part is formed by bending the front end (front edge) side of the cut and raised slit piece through about 90 degrees, and therefore, there are problems with manufacture as described below.
In other words, in the invention described in patent document 1, all of the bent parts are formed by bending the front end side of the slit piece and Continuation of PCT/JP2005/016864 English Translation of Int. Application therefore the bending forces in the same direction act on the thin plate-shaped fin material successively and when the bent part is formed, the fin material deforms in one direction in an unbalanced manner.
In addition, it is necessary to provide the slit pieces regularly at fixed pitch dimensions, however, as described above, in the invention described in patent document 1, the fin material tends to collect in one direction, and therefore, it is difficult to reduce the variation in the pitch dimension between the slit pieces. Then, if the variation in the pitch dimension between the slit pieces becomes greater, the possibility is high that the heat transfer rate is reduced and a desired heat exchange performance cannot be obtained.
In order to solve the above-mentioned problem, the inventors of the present invention have proposed a heat exchanger with an improved heat exchange performance, and with a simple fin shape, in the patent application of Japanese Patent Application No. 2004-62236.
In this earlier application, a fin for increasing the heat exchange area with air flowing around a tube is provided on the outer surface of the tube through which fluid flows and the fin is provided with a flat-shaped plate part and a collision wall formed by cutting and raising in an upright position a portion of the plate part and the collision walls are provided in a plural number symmetrically in the airflow direction.
Accordingly, when the collision walls are formed the bending forces in the directions in which the force on the upstream side and that on the downstream side of airflow cancel out each other act upon a thin plate-shaped fin material. Consequently, when the collision walls are formed, it is possible to prevent in advance the fin material from deforming in one direction in an unbalanced manner and therefore it is possible to keep the variation in the dimension of the collision walls small.
As a result, it is possible to improve productivity (to increase the production speed) of the fins with a simple shape while improving the heat exchange efficiency by increasing the heat transfer rate between the fin and air by utilizing the turbulent flow effect by the collision walls.
By the way, the above-mentioned earlier application relates to the improvement of the heat transfer performance in a single heat exchanger.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to improve, in a heat exchanger device in which a plurality of heat exchangers are arranged in series in the airflow direction, the heat transfer performance of a heat exchanger situated on the downstream side of airflow by utilizing a turbulent flow forming structure of a heat exchanger situated on the upstream side of airflow.
In order to attain the above-mentioned object, a first aspect of the present invention is a heat exchanger device in which a plurality of heat exchangers (10, 20) are arranged in series in the airflow direction, characterized in that the plurality of heat exchangers (10, 20) comprise tubes (11, 12) through which fluids flow, respectively, and fins (12, 22) provided on an outer surface of the tubes (11, 21) for increasing heat exchanging area with air flowing around the tubes (11, 21), and the fins (12) of the heat exchanger (10) on an upstream side of airflow among the plurality of heat exchangers (10, 20) are provided with turbulent flow forming means (12 c, 12 g) for stirring the airflow.
According to this, a turbulent flow is formed by stirring airflow at the fins (12) of the heat exchanger (10) on the upstream side of airflow, and therefore, it is possible to improve the heat exchange performance of the heat exchanger (10) on the upstream side of airflow by improving the heat transfer rate thereof. In addition, by making the influence of the turbulent flow formation on the upstream side of airflow exert also on the heat exchanger (20) on the downstream side of airflow, it is possible to realize the improvement of the heat exchange performance of the heat exchanger (20) on the downstream side of airflow by the turbulent flow formation also therein.
In a second aspect of the present invention according to the heat exchanger device of the first aspect, the fins (22) of the heat exchanger (20) on a downstream side of the airflow among the plurality of the heat exchangers (10, 20) are also provided with turbulent flow forming means (22 c, 22 g) for stirring the airflow.
According to this, in addition to the effect of the first aspect, the turbulent flow forming action of the heat exchanger (20) on the downstream side of airflow itself is added in the fins (22) thereof and, therefore, it is possible to further improve the heat exchange performance of the heat exchanger (20) on the downstream side of airflow.
In a third aspect of the present invention according to the heat exchanger device of the first or second aspect, a distance (L) between the plurality of the heat exchangers (10, 20) is equal to or less than 20 mm.
According to an experiment by the inventors of the present invention, it has been found that by setting the distance (L) to 20 mm or less as illustrated in FIG. 7 to be described later, it is possible to effectively improve the heat exchange performance of the heat exchanger (20) on the downstream side of airflow by effectively making the influence of the turbulent flow formation on the upstream side of airflow exert on the heat exchanger (20) on the downstream side of airflow.
In a fourth embodiment of the present invention according to any one of the heat exchanger devices of the first to third aspects, the fins (12, 22) have right-angled collision walls (12 c, 22 c) formed by cutting and raising in an upright position a portion of flat-shaped plate parts (12 a, 22 a), the right-angled collision walls (12 c, 22 c) are provided in a plural number symmetrically in the airflow direction, and the right-angled collision walls (12 c, 22 c) constitute the turbulent flow forming means.
In this manner, the turbulent flow forming means is specifically constructed by the collision walls formed by cutting and raising in an upright position the fin plate part.
Here, by providing the right-angled collision walls (12 c, 22 c) in a plural number symmetrically in the airflow direction, the bending forces in the directions in which the force on the upstream side and that on the downstream side of airflow cancel out each other act upon the thin plate-shaped fin material when the right-angled collision walls are formed. Consequently, when the collision walls are formed, it is possible to prevent in advance the fin material from deforming in one direction in an unbalanced manner and, therefore, it is possible to keep small the variation in the dimension of the collision walls.
In a fifth aspect of the present invention according to any one of the heat exchanger devices of the first to third aspects, the fins (12, 22) have V-shaped collision walls (12 g, 22 g) formed by cutting and raising into a V-shaped section a portion of the flat-shaped plate parts (12 a, 22 a), the V-shaped collision walls (12 g, 22 g) are provided such that the direction of the formation of the V-shaped section is reversed by turns in the airflow direction, and the V-shaped collision walls (12 g, 22 g) constitute the turbulent flow forming means.
In this manner, it may also be possible to construct the turbulent flow forming means specifically by the V-shaped collision walls formed by cutting and raising into the V-shaped section the fin flat part.
Then, by providing the V-shaped collision walls such that the direction of the formation of the V-shaped section is reversed by turns in the airflow direction, the bending stresses at the time of the cutting and raising formation of the fin material are cancelled out and it is possible to avoid a residual stress from occurring in one particular direction in the fin.
Consequently, when the V-shaped collision walls (12 g, 22 g) are formed, it is possible to prevent in advance the fin material from deforming in one direction in an unbalanced manner and, therefore, it is possible to keep the variation in the dimension of the V-shaped collision walls (12 g, 22 g) small.
In a sixth aspect of the present invention according to any one of the heat exchanger devices of the first to fifth aspects, the heat exchanger on the upstream side of the airflow among the plurality of the heat exchangers (10, 20) is a refrigerant heat dissipater for vehicle air conditioning (10) and the heat exchanger on a downstream side of the airflow is a radiator for cooling vehicle engine (20).
According to this, it is possible to effectively improve the heat exchange performance (heat dissipation performance) of the radiator (20) on the downstream side of airflow by the turbulent flow formation of airflow in the refrigerant heat dissipater (10) on the upstream side of airflow.
By the way, the symbols in the parentheses attached to each means described above indicate a correspondence with a specific means in the embodiments to be described later.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic sectional view showing a state in which a heat exchanger device according to a first embodiment of the present invention is mounted on a vehicle.
FIG. 1B is a partial section of a core part of the heat exchanger device in FIG. 1A.
FIG. 2 is a front view of a heat exchanger according to the first embodiment.
FIG. 3A is a partial perspective view of a core part of the heat exchanger according to the first embodiment of the present invention.
FIG. 3B is a sectional view taken along A-A line in FIG. 3A.
FIG. 4 is a sectional view showing another embodiment of collision walls of fins according to the first embodiment.
FIG. 5 is an enlarged sectional view of the fin part for explaining the definition of a cutting and raising height H and a pitch dimension P of an L-shaped section part.
FIG. 6 is an explanatory diagram of airflow in various heat exchanger devices in which a refrigerant heat dissipater and a radiator are arranged in series.
FIG. 7 is a graph of the heat dissipation performance ratio of a radiator.
FIG. 8 is a graph of a total airflow resistance ratio of the refrigerant heat dissipater and the radiator.
FIG. 9A is a partial perspective view of a core part of a heat exchanger according to a third embodiment of the present invention.
FIG. 9B is a sectional view taken along B-B line in FIG. 9A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

FIG. 1A to FIG. 5 and FIG. 6(a) show a first embodiment of the present invention and the present embodiment relates to a heat exchanger device for a vehicle in which a refrigerant heat dissipater for vehicle air conditioning and a radiator for cooling vehicle engine are arranged in series.
FIG. 1A is a diagram showing the heat exchanger device for a vehicle according to the present embodiment which is mounted on a vehicle, and FIG. 1B is a partial sectional view of a core part of the heat exchanger device for a vehicle. A refrigerant heat dissipater for vehicle air conditioning 10 and a radiator for cooling vehicle engine 20 are arranged in series with respect to a direction “a” of airflow (cooling air).
The mounting structure of the heat exchanger is explained specifically. There is formed an engine compartment 31 below a vehicle hood (bonnet) 30 and grill openings 32 a and 32 b are open in the most front part in the engine compartment 31. The refrigerant heat dissipater 10 and the radiator 20 are arranged in series at the portion immediately after the grill openings 32 a and 32 b. Here, the refrigerant heat dissipater 10 is arranged on the upstream side of airflow and the radiator 20 is arranged on the downstream side (on the rear side of the vehicle) of the refrigerant heat dissipater 10.
On the downstream side of the radiator 20, a cooling fan 22 composed of axial fans is arranged via a shroud 21. This cooling fan 22 is an electrically driven fan that rotates and drives an axial fan by an electric motor 22 a.
On the downstream side (on the rear side of the vehicle) of the cooling fan 22, an engine (internal combustion engine) 33 for vehicle traveling is mounted. This vehicle engine 33 is of a water-cooled type and the cooling water of the vehicle engine 33 is cooled by being circulated through the radiator 20 by a water pump, not shown.
In addition, the refrigerant heat dissipater 10 is connected to the compressor discharge side of a vehicle air conditioning refrigeration cycle, not shown, and cools the refrigerant by dissipating the heat of the compressor discharge refrigerant (high pressure side refrigerant) to airflow. In a refrigeration cycle using a normal CFC (freon)™ refrigerant, the refrigerant discharge pressure of the compressor is less than the critical pressure of the refrigerant and therefore the refrigerant dissipates heat while condensing in the refrigerant heat dissipater 10. In contrast to this, in a refrigeration cycle using a refrigerant such as carbon dioxide (CO2) etc., the refrigerant discharge pressure of the compressor becomes equal to or greater than the critical pressure of the refrigerant and therefore the refrigerant dissipates heat in a supercritical state without condensing in the refrigerant heat dissipater 10.
The reason that the radiator 20 is arranged on the downstream side of the refrigerant heat dissipater 10 is to preserve temperature differences from air both in the refrigerant heat dissipater 10 and in the radiator 20. In other words, in the constant operation state of the vehicle engine 33, the temperature of the engine cooling water in the radiator 20 becomes higher than the refrigerant temperature in the refrigerant heat dissipater 10 and, therefore, it is advantageous to arrange the radiator 20 on the downstream side of the refrigerant heat dissipater 10 in order to preserve the temperature differences from air both in the refrigerant heat dissipater 10 and in the radiator 20.
FIG. 2 illustrates a specific configuration of the refrigerant heat dissipater 10, wherein a plurality of tubes 11 through which refrigerant flows are arranged in parallel with predetermined spacing and fins 12 are provided between the plurality of the tubes 11. This fin 12 is joined to the outer surface of the tube 11 to promote heat exchange between refrigerant and air by increasing the heat transfer area with air.
On both the ends in the lengthwise direction of the tube 11, header tanks 13 and 14 are provided. The header tanks 13 and 14 extend in the direction perpendicular to the lengthwise direction of the tube 11 and are communicated with the refrigerant path in each tube 11. Then, on both the ends in the lamination direction of tubes and fins (in the vertical direction in FIG. 2) of a core part composed of the tubes 11, the fins 12, etc., side plates 15 and 16 constituting a reinforced member are arranged.
By the way, in the present embodiment, all of the tube 11, the fin 12, the header tanks 13 and 14 and the side plates 15 and 16 are formed from aluminum alloy, which is excellent in thermal conductivity, and these metal members 11 to 16 are joined together into one unit by brazing.
As shown in FIG. 1B and FIG. 3A or FIG. 3B, the tube 11 of the refrigerant heat dissipater 10 is a flat-shaped porous tube formed by extrusion work or drawing work, in which a plurality of refrigerant path holes 11 a are formed in parallel. The flat shape of the tube 11 is in parallel to the airflow direction “a”.
In addition, as shown in FIG. 3A or FIG. 3B, the fin 12 is a corrugated fin formed by being bent into a wavy shape so as to have a bent part 12 b that is curved so as to connect a flat-shaped plate part 12 a and its neighboring plate part 12 a. In the present embodiment, the wavy corrugated fin 12 is formed by applying a roller forming method to a thin plate metal material. The bent part 12 b of the fin 12 comes into contact with and is brazed to the flat-shaped part (plane part) of the tube 11 as shown in FIG. 3A or FIG. 3B.
Then, on the plate part 12 a of the fin 12, a plurality of collision walls 12 c having a shape into which a portion of the plate part 12 a is cut and raised in an upright position are provided. Here, cutting and raising in an upright position specifically means to cut and raise a portion of the plate part 12 a so as to be right angles with respect to the surface of the plate part 12 a, however, the cut and raised angle of the collision wall 12 c may be near 90 degrees, which are increased or decreased by a minute angle from 90 degrees.
Air flowing along the fin 12, that is, the surface of the plate part 12 a is caused to collide with the collision walls 12 to stir the airflow along the surface of the plate part 12 a, increasing the heat transfer rate between the fin 12 and the air.
Here, the plate part connected to the root part of the collision wall 12 c among the plate part 12 a of the fin 12 is referred to as a slit piece 12 d. The slit piece 12 d and the collision wall 12 c form an L-shaped section. Then, the L-shaped sections are arranged so as to be in a symmetrical relationship with respect to a virtual plane M perpendicular to the plate part 12 a between the upstream side of airflow and the downstream side of airflow.
Specifically, when the plate part 12 a is bisected into the upstream side and the downstream side in the airflow direction by the virtual plane M, the number of collision walls 12 c on the upstream side is equal to the number of collision walls 12 c on the downstream side, and on the upstream side of airflow, the downstream side of airflow of the slit piece 12 s is cut and raised in an upright position, while on the downstream side of airflow, the upstream side of airflow of the slit piece 12 d is cut and raised in an upright position.
By the way, the basic configuration of the refrigerant heat dissipater for vehicle air conditioning 10 may be the same as that of the radiator for cooling vehicle engine 20 and, therefore, symbols of the constituent members of the radiator for cooling vehicle engine 20 are written in the parentheses attached to the symbols of the corresponding members of the refrigerant heat dissipater 10 in FIG. 2, FIG. 3A, and FIG. 3B, and the specific explanation of the radiator for cooling vehicle engine 20 is omitted.
However, the pressure of the engine cooling water circulating through the radiator for cooling vehicle engine 20 is much lower than the refrigerant pressure in the refrigerant heat dissipater for vehicle air conditioning 10 and, therefore, it is not necessary to increase the pressure resistant strength of the tube 21 of the radiator 20 as is required for the tube 11 of the refrigerant heat dissipater 10. Because of this, the tube 21 of the radiator 20 has a simple flat-shaped section forming only one cooling water path as shown in FIG. 1B.
In the present embodiment, also on the fins 22 of the radiator 20 situated on the downstream side of airflow, collision walls 22 c and slit pieces 22 d are formed that constitute L-shaped sections similarly to the fin 12 of the refrigerant heat dissipater 10 as shown in FIG. 3A or FIG. 3B.
By the way, the L-shaped sections formed by the slit pieces 12 d and the collision walls 12 c are not limited to the shape shown in FIG. 3A and FIG. 3B and in contrast to this, as shown in FIG. 4, it may also be possible to form the collision walls 12 c and 22 c on the upstream side of airflow of the slit pieces 12 d and 22 d in the upstream side region of airflow of the fins 12 and 22 and on the other hand, to form the collision walls 12 c and 22 c on the downstream side of airflow of the slit pieces 12 d and 22 d in the downstream side region of airflow.
What is required is to symmetrically arrange the collision walls 12 c and 22 d in the upstream side region of airflow of the fins 12 and 22 and the collision walls 12 c and 22 c in the downstream side region of airflow.
Next, specific examples of the dimensions of the fins 12 and 12 are explained. The fins 12 and 22 are, as described above, corrugated fins formed by connecting the neighboring plate parts 12 a and 22 a by the bent parts 12 b and 22 b and by being bent into a wavy shape, and the fin pitch Pf of the corrugated fins 12 and 22 is twice the distance between the neighboring plate parts 12 a and 22 a, as shown in FIG. 3B, and the fin pitch Pf is, for example, 2.5 mm.
A plate thickness t (refer to FIG. 5) of the corrugated fins 12 and 22 is, for example, 0.05 mm, a height H (refer to FIG. 5) of the collision walls 12 c and 22 c is, for example, 0.3 mm, and a pitch P of the L-shaped section part is, for example, 0.5 mm.
In addition, a distance L (refer to FIG. 1B and FIG. 6) between the two heat exchangers 10 and 20 before and after in the airflow direction is preferably set to a short distance equal to or less than 20 mm and more specifically, it is preferable that the distance L=about 5 mm.
Next, the function and effect of the present embodiment are explained. FIG. 6(a) shows the airflow in the refrigerant heat dissipater 10 situated on the upstream side of airflow and the airflow in the radiator 20 situated on the downstream side of airflow in the present embodiment. By the way, the arranging configuration of the collision walls 12 c and 22 c and the slit pieces 12 d and 22 d on the fins 12 and 22 in FIG. 6(a) is the same as that in FIG. 4.
In the upstream side region of airflow in the refrigerant heat dissipater 10, as the collision wall 12 c has minute dimensions, the air that has entered passes through while maintaining an approximately laminar flow state, however, as the airflow approaches the downstream side, the stirring effect of the airflow by the collision wall 12 c increases in magnitude gradually. Because of this, in the downstream side region of airflow of the refrigerant heat dissipater 10, the airflow enters a turbulent flow state as shown in FIG. 6(a) and the heat transfer rate on the air side can be improved.
Here, since the distance L between the two heat exchangers 10 and 20 before and after in the airflow direction is set to a short distance equal to or less than 20 mm, it is possible to form a turbulent flow state of airflow also in the upstream side region of the radiator 20 by exerting the influence of the turbulent flow state in the downstream side region of airflow of the refrigerant heat dissipater 10 on the upstream side region of airflow of the radiator 20. An a part in FIG. 6(a) shows an influenced range of the turbulent flow state in the refrigerant heat dissipater 10.
From the above, it is possible to form the turbulent flow state both in the upstream side region and in the downstream side region of airflow in the fin 22 on the radiator 20 side, and therefore, it is possible to effectively improve the heat dissipation performance on the radiator 20 side.
In the present embodiment, the collision walls 12 c and 22 c on the upstream side and the collision walls 12 c and 22 c on the downstream side are provided so as to be symmetric with each other in the airflow direction, and therefore, the bending forces, the directions of which are set to cancel each other, act on the thin plate-shaped fin material at the time of the fin formation process.
Consequently, it is possible to prevent in advance the fin material from deforming in one direction in an unbalanced manner when the collision walls 12 c and 22 c are formed and to keep small the variation in the dimensions of the slit pieces 12 d and 22 d and the collision walls 12 c and 22 c.
As a result, it is possible to improve the productivity of the fins 12 and 22 with a simple shape while improving the heat exchange efficiency by increasing the heat transfer rate between air and the fins 12 and 22 using the turbulent flow effect by the collision walls 12 c and 22 c.

Second Embodiment

FIG. 6(b) shows a second embodiment, wherein the configuration of the fin 12 of the refrigerant heat dissipater 10 situated on the upstream side of airflow is the same as that of the first embodiment and the configuration of the fin 22, in opposition thereto, of the radiator 20 situated on the downstream side of airflow is the same as that of the prior art shown in FIG. 6(c).
In other words, on the fin 22 of the radiator 20 in the second embodiment, the collision wall 22 c as in the first embodiment is not formed but a slant louver 22 f is formed, which is formed by cutting and raising in a slant position through predetermined angles as in the prior art shown in FIG. 6(c). The cutting and raising direction of the slant louvers 22 f on the upstream side of the airflow is opposite to that on the downstream side of the airflow.
According to the second embodiment, the fin 22 itself of the radiator 20 does not comprise a forming means, however, it is possible to exert the influence of the turbulent flow state in the downstream side region of airflow of the refrigerant heat dissipater 10 also on the upstream side region of airflow of the radiator 20. As a result, it is possible to form a turbulent flow state of airflow also in the upstream side region of the radiator 20 as shown in the α part of FIG. 6(b).
Due to this, it is possible to improve the heat transfer rate by the formation of turbulent airflow also on the radiator side 20, and therefore, it is possible to improve the heat dissipation performance on the radiator side 20.
By the way, the prior art shown in FIG. 6(c) is a typical one, that has been commercialized, in which the slant louvers 12 f and 22 f formed by cutting and raising in a slant position through predetermined angles are formed both on the fin 12 of the refrigerant heat dissipater 10 and on the fin 22 of the radiator 20. In this prior art, air passes through between the louvers 12 f (22 f) in a laminar flow state, and therefore, it is not possible to improve the heat dissipation performance by the formation of turbulent flow by the collision walls 12 c and 22 c as in the first and second embodiments.
In addition, FIG. 6(d) shows a comparative example of the present invention, in which the collision wall 22 c is cut and raised in an upright position only on the fin 22 of the radiator 20 on the leeward side (downstream side in an airflow direction). In this comparative example, it is not possible to form the turbulent flow state of airflow in the fin 12 of the refrigerant heat dissipater 10 on the windward side (upstream side in an airflow direction), and therefore, it is not possible to improve the heat dissipation performance of the radiator 20 on the leeward side by utilizing the turbulent flow state of airflow in the refrigerant heat dissipater 10 on the windward side.
Next, the effect of the first embodiment is specifically explained based on the experiment result shown in FIG. 7 and FIG. 8. As the condition of the experiment shown in FIG. 7 and FIG. 8, the dimension example of each part of the fins 12 and 22 in the first embodiment is the same as the above-described dimensions. In other words, the fin plate thickness t=0.05 mm, the fin pitch Pf=2.5 mm, the height of the collision walls 12 c and 22 c H=0.3 mm, and the pitch P of the L-shaped section part=0.5 mm.
Then, it is assumed that the air temperature at the inlet is 25° C. (room temperature), the cooling water temperature at the inlet of the radiator 20 is 80° C., the flow velocity of the cooling air is 4 m/s, and the flow rate of cooling water for circulating to the radiator 20 is 40 L/min, and a state is set in which there is no heat dissipation by the refrigerant heat dissipater 10 on the windward side, and then, the heat dissipation performance (KW) of the radiator 20 according to the first embodiment and the heat dissipation performance (KW) of the radiator 20 according to the prior art shown in FIG. 6(c) are measured and the ratio (%) of the heat dissipation performance of the radiator 20 according to the first embodiment with respect to the heat dissipation performance of the radiator 20 according to the prior art, which is assumed to be 100%, is shown in FIG. 7.
By the way, it is needless to say that the body of the core part of the radiator 20 according to the first embodiment and that of the radiator 20 according to the prior art are set to the same dimensions.
With the radiator 20 according to the first embodiment, if the distance L is reduced to about 20 mm, it is possible to improve the heat dissipation performance to about 102% compared to the prior art.
Then, it has been confirmed that if the distance L is reduced to about 5 mm, it is possible to improve the heat dissipation performance of the radiator 20 to about 104% compared to the prior art.
Next, FIG. 8 shows the influence of the airflow resistance according to the first embodiment. The total airflow resistance (Pa) of the refrigerant heat dissipater 10 and the radiator 20 according to the first embodiment and the total airflow resistance (Pa) of the refrigerant heat dissipater 10 and the radiator 20 according to the prior art are measured and the ratio (%) of the total airflow resistance according to the first embodiment with respect to the total airflow resistance according to the prior art, which is assumed to be 100%, is shown in FIG. 8.
According to the first embodiment, if the distance L is reduced to 20 mm or less, the airflow resistance increases because a turbulent flow is formed in the airflow in the radiator 20 on the leeward side by the formation of a turbulent flow in the airflow in the refrigerant heat dissipater 10 on the windward side, however, the degree of the increase is very small compared to the prior art and therefore there is almost no practical problem.
By the way, although the heat dissipation performance ratio in the case of the second embodiment is not shown schematically in FIG. 7, the fin 22 of the radiator 20 does not comprise the turbulent flow forming means in the second embodiment, and therefore, the rate of improvement in the heat dissipation performance of the radiator 20 becomes smaller than the first embodiment, however, according to the experiment by the inventors of the present invention, it has been confirmed that it is possible to improve the heat dissipation performance of the radiator 20 to about 102% compared to that of the prior art also in the second embodiment if the distance L is reduced to about 5 mm.
By the way, according to an experiment by the inventors of the present invention, as the dimension range of the fins 12 and 22 having the right- angled collision walls 12 c and 22 c are preferably that the fin plate thickness t=0.01 to 0.1 mm, the height H of the collision walls 12 c and 22 c=0.1 to 0.5 mm, the pitch P of the L-shaped section part is in the range between about 1.5 times to five times of the height H from the standpoint of the improvement in heat exchanger performance, the fin formability, the fin strength, etc.

Third Embodiment

In the first embodiment, as the turbulent flow forming means in the refrigerant heat dissipater 10 and the radiator 20, the collision walls 12 c and 22 c are formed in an upright position from the plate parts 12 a and 22 a of the fins 12 and 22 and in the second embodiment, as the turbulent flow forming means in the refrigerant heat dissipater 10, the collision wall (collision part) 12 c is formed in an upright position from the plate part 12 a of the fin 12, however, in a third embodiment, as the turbulent flow forming means, collision walls having a V-shaped section are formed on the fins 12 and 22.
In other words, FIG. 9A and FIG. 9B show a configuration of fins 12, 22 according to the third embodiment, in which V-shaped collision walls 12 g (22 g) the V-shaped sectional part of which extends in the direction perpendicular to the airflow direction a are formed on the plate parts 12 a and 22 a of the fins 12 and 22. The V-shaped collision wall 12 g (22 g), which forms a turbulent flow by the collision and stirring of airflow, can be formed by the cutting and raising formation by a roller forming machine etc.
The geometry of the V-shaped collision wall 12 g (22 g) is stated specifically below. The V-shaped collision walls 12 g (22 g) are formed so that the direction of the formation of the V-shaped section is reversed vertically by turns in the airflow direction Here, the top part of the V-shaped section is situated near the plate parts 12 a and 22 a and the fork end parts of the V-shaped section are situated on the side departing from the plate parts 12 a and 22 a.
Such V-shaped collision walls 12 g (22 g) are arranged in a staggered manner with respect to the plate parts 12 a, 22 a (in other words, the fin material surface S before the cutting and raising formation) so as to sandwich the plate parts 12 a, 22 a.
According to the third embodiment, the airflow collides with the V-shaped collision walls 12 g (22 g) and is stirred, and then a turbulent flow of airflow is formed and, therefore, it is possible to improve the heat transfer rate of the fins 12 and 22 by the formation of the turbulent flow.
Then, by forming the V-shaped collision walls 12 g on the fin 12 of the refrigerant heat dissipater 10 on the windward side and by forming a turbulent flow of airflow in the downstream region of the fin 12, it is possible to form a turbulent flow of airflow in the upstream region of the fin 22 of the radiator 20 on the leeward side. Due to this, it is possible to effectively improve the heat dissipation performance of the radiator 20 on the leeward side also in the third embodiment as in the first and second embodiments.
In addition, also in the third embodiment, as shown in FIG. 9B, the V-shaped collision walls 12 g and 22 g on the upstream part and those on the downstream part are formed symmetrically with each other with respect to the virtual plane M in the airflow direction “a”. Then, the direction of the formation of the V-shaped section is reversed vertically by turns in the airflow direction “a” and, therefore, the bending forces produced at the time of the cutting-and raising formation of the fin material are cancelled out and the residual stress in the specific one direction can be prevented from remaining in the fin.
Consequently, when the V-shaped collision walls 12 g and 22 g are formed, it is possible to prevent in advance the fin material from deforming to one side and, therefore, it is possible to keep small the variation in the dimension of the V-shaped collision walls 12 g and 22 g.
In addition, the individual sections themselves of the V-shaped collision walls 12 g and 22 g are symmetric in the V-shape, and therefore, the number of V-shaped collision walls 12 g and 22 g may be odd or even.

Other Embodiments

In the embodiments described above, the heat exchanger device for vehicle in which the refrigerant heat dissipater 10 and the radiator 10 are arranged in series is explained, however, the present invention can be applied widely to various purposes, not limited to those for vehicle, provided the heat exchanger device is one in which a plurality of heat exchangers are arranged in series in the airflow direction.

Claims

1. A heat exchanger device in which a plurality of heat exchangers are arranged in series in an airflow direction, wherein:

the plurality of heat exchangers comprise tubes through which fluids flow, respectively, and fins provided on an outer surface of the tubes for increasing heat exchanging area with air flowing around the tubes; and

the fins of the heat exchanger on an upstream side of airflow among the plurality of heat exchangers are provided with turbulent flow forming means for stirring the airflow.

2. The heat exchanger device as set forth in claim 1, wherein the fins of the heat exchanger on a downstream side of the airflow among the plurality of heat exchangers are also provided with turbulent flow forming means for stirring the airflow.

3. The heat exchanger device as set forth in claim 1, wherein a distance between the plurality of heat exchangers is equal to or less than 20 mm.

4. The heat exchanger device as set forth in claim 1, wherein:

the fins have right-angled collision walls formed by cutting and raising in an upright position a portion of flat-shaped plate parts;

the right-angled collision walls are provided in a plural number symmetrically in the airflow direction; and

the right-angled collision walls constitute the turbulent flow forming means.

5. The heat exchanger device as set forth in claim 1, wherein:

the fins have V-shaped collision walls formed by cutting and raising into a V-shaped section a portion of the flat-shaped plate parts;

the V-shaped collision walls are provided such that a direction of formation of the V-shaped section is reversed by turns in the airflow direction; and

the V-shaped collision walls constitute the turbulent flow forming means.

6. The heat exchanger device as set forth in claim 1, wherein the heat exchanger on the upstream side of the airflow among the plurality of the heat exchangers is a refrigerant heat dissipater for vehicle air conditioning and the heat exchanger on a downstream side of the airflow is a radiator for cooling vehicle engine.