US20130327512A1

US20130327512A1 - Heat exchanger

Info

Publication number: US20130327512A1
Application number: US13/985,959
Authority: US
Inventors: Friedrich Brotz; Volker Kurz
Original assignee: Behr GmbH and Co KG
Current assignee: Mahle Behr GmbH and Co KG
Priority date: 2011-02-22
Filing date: 2012-02-22
Publication date: 2013-12-12
Also published as: DE202011003054U1; EP2678629B1; EP2678629A1; WO2012113836A1

Abstract

The invention relates to a heat exchanger comprising a block, which has fins and pipes and which is arranged between two reservoirs, wherein each fin comprises several fin sections and each fin section is approximately V-shaped and the two flanks forming a fin section each have several air slits, which extend perpendicularly to the flow direction of a medium flowing through the fin section, wherein the two flanks of the fin section are connected by means of a first connecting surface and/or the flanks of two consecutive fin sections across from each other are connected by means of a second connecting surface, wherein the first connecting surface and/or the second connecting surface has a fin section cross-section variation element, which is directed into the intermediate space between the flanks forming a fin section and/or the flanks of two consecutive fin sections that are across from each other.

Description

The invention relates to a heat exchanger comprising a block which has fins and tubes and is arranged between two reservoirs, wherein each fin comprises a plurality of fin arches and each fin arch is of approximately V-like design and the flanks forming a fin arch each have a plurality of air slits which extend transversely with respect to the flow direction of a medium flowing through the fin arch.
Customary heat exchangers comprise an inlet box and an outlet box which are designated below as reservoirs, wherein a block is arranged between the two reservoirs, in which block there are situated tubes which connect the two reservoirs to one another. Here, the heat exchanger is arranged in front of the combustion engine. A coolant flows through the two reservoirs and the tubes and is heated by heat given off by the combustion engine. The fins formed between the tubes are traversed by an airflow which absorbs the heat given off by the coolant and removes it from the region of the heat exchanger. The coolant thus cooled is fed back to the combustion engine.
U.S. Pat. No. 6,968,891 B2 discloses a V-like fin arch which is formed by two opposite flanks, wherein each flank has a plurality of air slits which are formed transversely with respect to a flow direction of a medium which is guided through the intermediate space between the flanks. The air slits here have the task of swirling the medium so as to thereby allow a better heat exchange. In the case of V-shaped fin arches, the problem exists that the flow through the wide region of the V-shaped cross section takes place at high speed, with the result that these flows of the medium can also be designated as jets. For this reason, this part of the airflow does not participate in the cross exchange which is caused by the air slits which are present in the flanks of the fin arch.
According to U.S. 2007/0012430 A1, a heat exchanger is known which has fins which are formed from a plurality of fin arches which have a rectangular cross section. The two flanks forming the respective fin arches here have air slits for swirling the medium flowing through the fin arches, wherein the flanks are connected to one another in a meander-like manner via a respective connecting surface which has projections which are formed transversely with respect to the flow direction of the air. These projections improve the stability of the fin arch during production, in particular during bending, and the formation of a stable rectangular cross section of the fin arches is thus made possible.
U.S. 2009/0173480 A1 discloses a heat exchanger which has a fin which is arranged in thermal contact with a tube. The fin comprises various fin arches with a rectangular cross section. The connection between the flanks of a fin arch here comprises a plurality of elevations which are directed in the direction of the interior space between the flanks of the fin arch and interrupt the flow of the medium. Consequently, the flow is disturbed and it can no longer shoot through unimpeded, but a cross exchange is forced, thereby leading to a better heat transfer.
Owing to the parallel setting of the flanks of the fin arch and the creation of a rectangular cross section of the fin arch, the jets are indeed reduced but cannot be completely prevented since the air slits do not extend into the bending radius of the fin arch since the fin otherwise become too unstable and the air slits would buckle during production.
The object on which the invention is based is to specify a fin which has stably formed V-like fin arches and in which there are avoided regions having a high speed of the medium flowing through the fin arches in the flow direction, which regions cannot participate in the cross exchange of the air slits.
According to the invention, the object is achieved in that the two flanks of the fin arch are connected via a first connecting surface and/or the opposite flanks of two successive fin arches are connected via a second connecting surface, wherein the first and/or the second connecting surfaces have a fin arch cross section variation element which is directed into the intermediate space between the flanks forming a fin arch and/or the opposite flanks of two successive fin arches. This has the advantage that an improvement of the flow through the fin is achieved, with the result that the cooling power of the heat exchanger is improved. In addition to maintaining a stable construction of the fin having V-like fin arches, the cross section of the fin arch is varied in terms of depth or width such that all the cross-sectional regions in the flow direction of the medium which extend parallel to the flanks of the fin arch can reliably participate in the cross exchange through the air slits.
Advantageously, each connecting surface is situated opposite an open region which is formed by the two flanks which are connected by the connecting surface, wherein the extent of the open region between the two flanks is smaller than the extent of the connecting surface between the two flanks. Such a design of the V-shaped fin arch allows the introduction of different forms of the fin arch cross section variation element into the intermediate space between the two flanks. The open region between the flanks of two successive fin arches here depends on the number of fin arches.
In one refinement, the fin arch cross section variation element is designed as a convexity which is directed into the intermediate space between the flanks and which extends approximately parallel to the longitudinal extent of the flanks. This has the advantage that the cross section of the fin arch is varied in terms of width, with the result that all the flow ducts have the same cross section. Thus, cross-sectional shapes with large cross sections are eliminated, which prevents the formation of a jet. As a result, a better cross exchange takes place, with the result that the heat exchange is likewise improved.
The use of a convexity as fin arch cross section variation element allows a simple production of the fin arch cross section variation element.
Alternatively, the fin arch cross section variation element is designed as a web which is directed into the intermediate space between the flanks and which extends approximately parallel to the longitudinal extent of the flanks. This refinement also represents a cross-sectional change of the fin arch in terms of width and allows the uniform formation of all the flow ducts having one and the same cross-sectional shape which are formed by the flanks, with the result that the formation of jets is eliminated.
Advantageously, the fin arch cross section variation element extends to approximately half the height of the intermediate space between the flanks. As a result, a particularly symmetrical configuration of the fin combined with a simple production is obtained.
In a variant, the first and/or second connecting surface having the fin arch cross section variation element is of convex design, wherein the convexity regions which enclose the fin arch cross section variation element move in an opposite direction to the fin arch cross section variation element. Owing to the fact that an additional convexity or a web is introduced in the width of the V-like shape of the fin arch, the flow within the flow ducts thus formed is made uniform.
In another embodiment, the fin arch cross section variation element is designed as a flap-like air-guiding element. This has the advantage that a cross section variation occurs as a result of the flap-like air-guiding element which projects flat into the intermediate space between the two flanks. This cross section variation directed into the depth of the fin arch has the consequence that the flow of the medium which moves along the first or second connecting surface is directed downwardly into the region of the air slits and thus can participate in the cross exchange of the flow of the medium within the flow duct formed by the flanks.
In one refinement, the flap-like air-guiding element is folded toward the intermediate space between the two flanks. As a result of this folding, the airflow is influenced in the depth of the intermediate space.
Advantageously, an angle of the folding of the flap-like air-guiding element to the connecting surface depends on the depth of the respective fin arch. Thus, the angle of the folding can be determined depending on the application of the heat exchanger so that the heat exchanger allows a reliable heat exchange during each operating state.
In particular, the flap-like air-guiding element is stamped out of the connecting surface, thereby allowing a particularly simple production of the air-guiding element.

The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures illustrated in the drawing, in which:

FIG. 1 shows an illustration of a heat exchanger

FIG. 2 shows an assembly of fin and tube of the heat exchanger according to FIG. 1

FIG. 3 shows a configuration of a fin for depthwise flow engagement

FIG. 4 shows a configuration of a fin for widthwise flow engagement.

Identical features are denoted by identical reference signs.
FIG. 1 illustrates a heat exchanger 1, in particular a coolant cooler, which comprises a block 2 which is arranged between two reservoirs 3, 4 designed as water boxes. Each reservoir 3, 4 here has a base 5, 6 to which the block 2, which is closed off by a side part 7, is connected. The block 2 comprises a plurality of tubes 8 and a plurality of fins 9, where tube 8 and fin 9 are always arranged alternately with respect to one another. The reservoir 4 here has a connecting piece 11 into which a cooling medium derived from the combustion engine (not shown further) and heated thereby flows, which cooling medium is passed through the tubes 8 of the block 2 to the second reservoir 3. Through the block 2, in particular the fins 9, there is passed a gaseous medium, preferably air, which absorbs the heat of the cooling medium flowing through the tubes 8 and removes the heat from the heat exchanger 1. In this way, the cooling medium is cooled. The second reservoir 3 of the heat exchanger 1 into which the cooled cooling medium flows comprises a further connecting piece 10 through which the cooling medium is discharged from the heat exchanger 1 and fed back to the combustion engine.
FIG. 2 illustrates in more detail an assembly consisting of the fin 9 and the tube 8, from which it can be seen that the fin 9 comprises a plurality of V-shaped fin arches 9 a. The alternating arrangement of tubes 8 and fins 9 allows a high efficiency of the heat exchanger 1 during heat dissipation.
FIG. 3 illustrates a V-like fin 9 in which a fin arch 9 a comprises two flanks 12, 13, wherein each flank 12, 13 has a plurality of air slits 14 which are formed transversely with respect to the flow direction of the medium flowing through the fin arch 9 a. The flow direction of the medium through the fin arches 9 a here is provided in the X direction.
The two flanks 12, 13 of the fin arch 9 a are at an acute angle to one another, being spaced apart from one another at the underside by an open region Y. At the upper side, the flanks 12, 13 of the fin arch 9 a are connected to one another by a connecting surface 15. The flanks 13 are adjoined by a second connecting surface 16. The flanks 12, 13 and the connecting surfaces 15, 16 here form the fin arch 9 a. The connecting surface 15, 16 connecting the flanks 12 and 13 is of planar design and has a substantially wider extent than the open region Y with which the flanks 12 and 13 are situated opposite one another at their foot or head side.
A plurality of flap-like air-guiding plates 17 are formed behind one another in the longitudinal extent of the connecting surface 15 or 16, of which only two air-guiding plates 17 situated behind one another are represented in each case in FIG. 3. The flap-like air-guiding plate 17 here is stamped out of the connecting surface 15 or 16, wherein three sides of the flap-like air-guiding plates 17 are detached from the connecting surface 15 or 16, whereas the fourth side of the air-guiding plate 17 continues to be connected to the connecting surface 15 or 16 and forms a bending edge 17 a. Along this bending edge 17 a which is arranged transversely with respect to the longitudinal extent of the flank 12, 13, the freely movable end of the air-guiding plate 17 is directed downwardly into the intermediate space 20 between the flanks 12, 13 of the fin arch 9 a in such a way that it is transverse with respect to the flow direction of the medium flowing through and thus causes swirling. As a result of this positioning, the medium flowing past the air-guiding plates 17 is deflected downwardly into the region of the air slits 14 and can thus participate in the cross exchange of the heat. The free end of the air-guiding plate 17 has an angle α of folding with respect to the connecting surface 15. This angle α of folding and the spacings and lengths of the flap-like air-guiding plates 17 depend on the depth of the fins 9 and the critical operating state of each application of the heat exchanger 1, whereas the open region Y depends on the fin density.
Owing to the improvement of the cross exchange, the heat transfer from the cooling medium flowing in the tube 8 to the gaseous medium flowing through the fins 9 is improved, which increases the efficiency of the heat exchanger 1. Owing to the flap-like air-guiding plates 17, the cross section of the fin arch 9 a is varied depthwise, with the result that the formation of jets is eliminated.
FIG. 4 illustrates a second exemplary embodiment of the fin 9, wherein a fin arch 9 a likewise comprises two flanks 12 and 13 inclined at an acute angle with respect to one another, wherein the flanks 12, 13 have an open region Y at their foot and/or head side. This open region Y is opposite the connecting surface 15, 16, which is wider by a multiple than the open region Y. As already explained in connection with FIG. 3, the flank 13 is also in this case adjoined by a second connecting surface 16, wherein the fin arch 9 a is likewise formed by the flanks 12, 13 and the first connecting surface 15 and the second connecting surface 16.
In order to influence the cross section of the fin arch 9 a in its width, each connecting surface 15 or 16 has a respective convexity 18, 19 which extends in the direction of the intermediate space 20 between the flanks 12, 13. Here, the convexities 18 or 19 are formed along the entire longitudinal extent of the fin arch 9 a. The convexity 18, 19 has a radius R_I, whereas further convexities 21, 22 and 23, 24 of the connecting surfaces 15, 16 have the radius R_A. The further convexities 21, 22 and 23, 24 enclose the convexity 18 or 19 and are formed in the opposite direction to the convexities 18, 19. The spacing between the outer contours of the convexity 18, 19 and the outer contours of the further convexities 21, 22 or 23, 24 is designated as H. Here, the convexity 18, 19 which has a width of Z>0, is incorporated in the width of the V-shape. Owing to this convexity 18, 19 there results an engagement in the width of the cross section of the fin arch 9 a and accordingly a flow engagement in which all the flow ducts have the same cross-sectional shape, with the result that the formation of the jet is eliminated, since the flow rate of the medium within all fin arches 9 a is made uniform. The height H of the convexity 18, 19 here depends on the fin height and the application of the heat exchanger 1. The radii R_Aor R_Idepend on the fin density and on the fin height. The fin 9 illustrated in FIG. 4 also has air slits (not represented in more detail) on the flanks 12, 13. The flanks of the convexity can also contain air slits.
In a form which is not represented further, the convexity 18, 19 can also be replaced by a web (Z=0), which has the same influence on the cross section of the fin 9 and thus also on the flow behavior of the medium flowing through the fin arches.
In addition to increasing the cooling power, the heat exchanger 1 according to the invention also has the advantage that its overall depth or its fin density can be reduced while maintaining the same cooling power.

Claims

1. A heat exchanger comprising a block which has fins and tubes and is arranged between two reservoirs, wherein each fin comprises a plurality of fin arches and each fin arch is of approximately V-like design and the two flanks forming a fin arch each have a plurality of air slits which extend transversely with respect to the flow direction of a medium flowing through the fin arch, wherein the two flanks of the fin arch are connected via a first connecting surface and/or the opposite flanks of two successive fin arches are connected via a second connecting surface, wherein the first and/or the second connecting surface have a fin arch cross section variation element which is directed into the intermediate space between the flanks forming a fin arch and/or the opposite flanks of two successive fin arches.

2. A heat exchanger comprising a block which has fins and tubes and is arranged between two reservoirs, wherein each fin comprises a plurality of fin arches and each fin arch is of approximately V-like design and the two flanks forming a fin arch, each have a plurality of air slits which extend transversely with respect to the flow direction of a medium flowing through the fin arch, wherein the two flanks of the fin arch are connected via a first connecting surface and/or the opposite flanks of two successive fin arches are connected via a second connecting surface and wherein each connecting surface is opposite an open region which is formed by the two flanks which are connected by the connecting surface, wherein the extent of the open region between the two flanks is smaller than the extent of the connecting surface between the two flanks.

3. The heat exchanger as claimed in claim 1, wherein the fin arch cross section variation element is designed as a convexity which is directed into the intermediate space between the flanks and which extends approximately parallel to the longitudinal extent of the flanks.

4. The heat exchanger as claimed in claim 1, wherein the fin arch cross section variation element is designed as a web which is directed into the intermediate space between the flanks and which extends approximately parallel to the longitudinal extent of the flanks.

5. The heat exchanger as claimed in claim 3, wherein the fin arch cross section variation element extends to approximately half the height of the intermediate space between the flanks.

6. The heat exchanger as claimed in claim 3, wherein the first and/or second connecting surface having the fin arch cross section variation element is of convex design, wherein the convexity regions which enclose the fin arch cross section variation element move in an opposite direction to the fin arch cross section variation element.

7. The heat exchanger as claimed in claim 1, wherein the fin arch cross section variation element is designed as a flap-like air-guiding element.

8. The heat exchanger as claimed in claim 7, characterized in that wherein the flap-like air-guiding element is folded toward the intermediate space between the two flanks.

9. The heat exchanger as claimed in claim 7, wherein an angle of folding of the flap-like air-guiding element to the connecting surface depends on the depth of the fin arch.

10. The heat exchanger as claimed in claim 7, wherein the flap-like air-guiding element is stamped out of the connecting surface.