Cross flow heat exchanger

Abstract

The invention relates to a cross flow heat exchanger with a panel-and-slat design, consisting of a plurality of individual components (12, 14, 16) which together form a stack (10), with at least: - a first component (12) which permits a fluid passage of a medium in one direction, - a second component (14) which permits a fluid passage of this or another medium in another direction, - a third component (16) which, arranged between the first (12) and the second (14) component, creates a fixed bond between them, and - fluid-conducting channels (18) which engage through the end of the stack (10) at least in some portions and of which at least one channel portion (20) is used to supply and another channel portion (20) is used to discharge the medium for the first component (12).

Description

[0001] Cross-flow heat exchanger

[0002] The invention relates to a cross-flow heat exchanger in plate and strip construction, consisting of a plurality of individual components which form a stacked assembly.

[0003] A cross-flow heat exchanger directs the material flows in such a way that their directions intersect. These heat exchangers are essentially something between a countercurrent and a cocurrent heat exchanger. Cross-flow heat exchangers, for example, can be used to heat a fluid flow to a specific, fixed temperature.

[0004] Heat exchangers of this type, also called finned coolers, are state of the art, see DE 20 208 748 U1 . Using air as the cooling medium, such heat exchangers are often used to cool hydraulic fluids for the working hydraulics of mechanical systems, such as construction machinery or the like, for hydrostatic travel drives or as oil coolers for heavily loaded gearboxes, particularly in wind turbines. During operation of such systems, the heat exchangers are exposed not only to mechanical loads but also, to a particularly high degree, to thermal loads due to the high operating temperature of the fluids to be cooled. This is particularly the case when intermittent operation results in individual temperature jumps, which, due to material expansion, leads to severe stresses in the package of components that are usually joined by brazing to form a rigid block.The result is stress cracks, particularly in the area of ​​the soldered seams, with the risk of failure of the heat exchanger and thus endangering the associated connected system.

[0005] In order to effectively counteract such stress cracks, a cross-flow heat exchanger has already been proposed in DE 10 2010 046 913 A1, in particular for fluid cooling devices, with a package of plane-parallel plates, wherein flow areas for a hot medium and for a cooling medium are formed alternately between pairs of superimposed plates, which are each laterally delimited by profile strips that keep the plates at a distance and form soldering surfaces that lie against the plates, wherein the profile strips extend at the flow areas of one medium and the other medium along edges of the plates that abut one another at an angle, and wherein at least the profile strips of the flow areas of the cooling medium have a base body, two legs extending from the base body along the soldering surfaces, and between these a recess that is open to the adjacent flow area,which is delimited by flat wall sections, at least in the area adjacent to its inner end section. Because, in this known solution, the recess has flat wall sections starting from the inner end section, an at least approximately linear change in the flexural strength can be achieved over the length of the profile legs, so that optimal bending behavior of the legs is achieved by selecting the length and / or inclination of these flat wall sections relative to the brazing surface plane. In addition to stress cracks due to thermal stress, the service life is determined by changing operating pressures. In order to supply the stacked assembly with the medium to be cooled, box-shaped chambers are brazed on from the outside, which serve as inflow and outflow chambers for the flowable medium.Typically in the form of hydraulic oil to be cooled from a hydraulic circuit connected to the heat exchanger. A corresponding inflow chamber and an outflow chamber for the stacked assembly of a cross-flow heat exchanger are shown in DE 102 30 042 A1.

[0006] Based on this prior art, the invention seeks to improve known heat exchangers, particularly by enabling cost-effective production. This objective is achieved by a cross-flow heat exchanger having the features of patent claim 1 in its entirety.

[0007] The cross-flow heat exchanger according to the invention consists of a plurality of individual components which form a stacked assembly with one another, with at least a first component which enables a fluid passage of a medium in one direction, a second component which enables a fluid passage of this or another medium in a further direction, a third component which is arranged between the first and the second component and creates a fixed connection between them, and fluid-carrying channels which at least partially pass through the stacked assembly at the end and of which at least one channel section serves to supply and another channel section to remove the medium for the first component.

[0008] Because the fluid-carrying channels mentioned are essentially an integral part of the stacked assembly, formed from the individual components, they do not need to be designed as inlet or outlet chambers from the outside, placed laterally on the stacked assembly and firmly connected to it, in particular by soldering or welding, as demonstrated in the prior art. This significantly simplifies the manufacture of the heat exchanger and helps save manufacturing costs. Furthermore, the free cross-sections of the fluid-carrying channels can be reduced within the internal routing, thus avoiding flow losses during operation, particularly due to turbulence within the media flow.Since the cross-flow heat exchanger according to the invention requires fewer solder joints or soldering surfaces for its construction due to the integral fluid flow, the associated thermal input is correspondingly reduced, thus preventing the introduction of excessive thermal stresses and effectively counteracting the risk of stress cracks occurring within the solder joints of the rigid heat exchanger block. This enables long-term operation of the cross-flow heat exchanger according to the invention.

[0009] The components mentioned in the stack can be designed as identical parts, which benefits functional reliability. The components can also be designed as identical parts in the form of a modular system, so that heat exchangers of different sizes can be constructed and implemented cost-effectively using only a few, different components. It goes without saying that in a larger stack sequence, the third component is arranged alternately between the first and second components and subsequently between the second and first components, and so on. In the stack sequence, a third component is therefore always incorporated on the top and bottom of a first or second component.In a preferred embodiment of the cross-flow heat exchanger according to the invention, the first component is enclosed on its outer circumference by a frame whose overall height corresponds to the overall height of at least one flow guide channel, which extends in a fluid-conducting manner between two adjacent channel sections, which are at least partially enclosed by this edge. The frame can be formed as a single piece, for example, as a stamped part, or the frame can be composed of individual strip-shaped frame parts, which are available in different lengths for constructing different heat exchanger sizes, which benefits the basic design of the heat exchanger as a modular system.Preferably, the strip-shaped frame parts adjoin one another in a horizontal installation position in such a way that a corner area is left free in each case, wherein the components adjacent to the frame parts in the stack assembly preferably have a contour recess following the respective corner area. The corner areas left free in this way can serve to accommodate assembly rods as an assembly aid, whereby a type of box-shaped auxiliary assembly frame is created which, when loaded with the components in a predeterminable sequence from the free upper side, forms the stack assembly, which then, by means of appropriate heat input, leads to firm connections between the components and thus to the entire block-like heat exchanger. Independently of this, it is also possible to provide the left-free corner areas in the stack assembly for the introduction of a weld seam in order to obtain the stack assembly as a heat exchanger block.

[0010] In any case, it is advantageous if the third component is formed from a flat plate with recesses at the ends the size of the adjacent channel sections and is coated with solderable materials. Thermal heat input then melts the solder of the plate, which is applied flatly on both opposite sides, forming strong connections with the adjacent components and forming the stacked assembly.

[0011] In a further preferred embodiment of the cross-flow heat exchanger according to the invention, the components arranged at the top and bottom in the stacking sequence are each formed from a flat end plate, at least one of which has the inlet and / or outlet for one medium, which is formed from a separate connecting piece that is placed on one side of the end plate and firmly connected to it. In this way, the connecting pieces can also be standardized and attached or soldered to the end plates of the stack as an additional component.

[0012] In a preferred embodiment of the cross-flow heat exchanger according to the invention, the free cross-sections for the individual channel sections are rectangular, preferably square. These channel sections can be manufactured simply and cost-effectively and, due to their direct integration into the stacked assembly, require little installation space, which benefits the space-saving design of the heat exchanger.

[0013] In a further preferred embodiment of the cross-flow heat exchanger according to the invention, when multiple flow guide channels are used for one medium, these are each formed from a longitudinal channel extending from a channel section at one end to the opposite channel section at the other end. In this way, maximum heat transfer is achieved between the media guide of one component and the second component, which are preferably separated from each other in a media-tight manner by the heat-conducting third, plate-like component. To improve heat transfer in this regard, the second component is provided with at least one baffle, which, through its shape, both enlarges the heat transfer surface and controls the flow for better heat transfer. A typical design is corrugated in a zigzag shape.The baffle opens into the open air at the free end faces of the heat exchanger and runs transversely or crosswise to the longitudinal channels of the respective first components. The baffle of the second component serves primarily to guide the air flow, which is preferably passed through by a motor-driven fan at high flow velocity.

[0014] In addition to cooling hydraulic oil, it is also possible to cool water-glycol mixtures or other liquids and gases, such as water as an operating medium or charge air of a compressor.

[0015] Overall, the cross-flow heat exchanger according to the invention creates a structure that essentially allows the production of a plate and strip-based cross-flow heat exchanger as a whole with only a single soldering process, which has no equivalent in the prior art.

[0016] In the following, the cross-flow heat exchanger according to the invention is explained in more detail using two exemplary embodiments according to the drawing. In this case, the following are schematic and not to scale representations:

[0017] Figure 1 is a partial perspective view of a half heat exchanger according to a first embodiment;

[0018] Figure 2 is an exploded view, a view corresponding to Figure 1 of components of the heat exchanger; Figure 3 is an exploded view, a perspective

[0019] Side view of another embodiment of a cross-flow heat exchanger with fluid guidance as shown by the arrow;

[0020] Figure 4 is a plan view of a component of the heat exchanger according to Figure 3 in the form of a heat exchanger plate; and

[0021] Figure 5 shows a perspective side view of the heat exchanger as a whole, composed of the components shown in Figures 3 and 4.

[0022] The cross-flow heat exchanger according to the invention consists of a plurality of individual components that form a stacked assembly, designated as a whole by 10, with first components 12 that allow fluid passage of a medium in a predeterminable direction. Furthermore, second components 14 are present, each of which allows fluid passage of this or another medium in a further predeterminable direction. Third components 16, arranged between the respective first component 12 and the second component 14, establish a solid assembly among the aforementioned components 12, 14, 16.

[0023] Furthermore, as can be seen in particular from Figure 2, all components 12, 14, 16 have fluid-carrying channels 18 that extend through the stack assembly 10 at the ends. These channels 18 are only shown for the front half of the heat exchanger; a corresponding channel layout is also provided for the second half of the heat exchanger at the other end. In this respect, the front channel sections 20, formed from the front fluid-carrying channel 18, serve to supply the medium or fluid, and the other channel sections not shown at the other end of the heat exchanger serve to remove the medium. According to the illustration in Figure 2, the fluid-carrying channels 18 have a rectangular opening cross-section, and in the stack assembly 10, the free channel sections 20 formed in this way are arranged one above the other in a media-carrying arrangement.

[0024] As can be further seen from Figure 2, the first component 12 is enclosed on its outer circumference by a frame 22, the overall height of which corresponds to the overall height of a plurality of flow guide channels 24, which extend in a fluid-conducting manner between two adjacent channel sections 20, which are at least partially enclosed by this frame 22. To form the individual flow guide channels 24, channel-like longitudinal guides 26 are introduced, which, at a distance from one another, each accommodate a flow guide channel 24 between them.In this respect, the flow guide channels 24 run in a horizontal orientation and the hot medium supplied via the front channel 18, for example in the form of hydraulic medium, passes via the front channel section 20 of the first component 12, via the flow guide channels 24 running parallel to one another, to the rear channel section 20 (not shown in detail) and thus to the fluid-carrying channel 18, which then discharges the cooled medium in the form of hydraulic oil from the heat exchanger.

[0025] 1 and 2, the frame 22 is composed of individual, strip-shaped frame parts 28 which, adjacent to one another, leave a corner region 30 free. The components 14, 16 in the stack assembly 10 which are adjacent to the frame parts 28 also have a contour recess 32 following the respective corner region 30 in the manner of this corner region 30. As can be seen from Figure 1, the corner regions 30 and the subsequent contour recesses 32 arranged one above the other in the stacking sequence form an engagement point for a rod-like assembly aid along which the individual components 12, 14, 16 can be stacked, or as shown in Figure 1, if necessary after the assembly aid has been removed or omitted, the contours left free serve to create a weld seam 34 extending over the entire stacking sequence (see Figure 1).Otherwise, the components 12, 14, 16 lying one above the other in the stack assembly 10 are thermally treated in a corresponding assembly receptacle (not shown) and the soldering media arranged on both sides of the third component 16 as coating material bond to the respective overlying component 14 and an underlying component 12, as shown in Figure 2.

[0026] Instead of a plurality of flow guide channels 24, it is also possible to omit the rod-like longitudinal guides 26, allowing free fluid passage from the front channel section 20 to the rear channel section 20 along a single flow channel across the entire cross-section defined by the frame 22. Each frame 22 consists of four strips 36 or longitudinal bars, the overall lengths of which are essentially freely definable and which are adapted to the size of the heat exchanger to be realized.

[0027] As further shown in the figures, the second component 14 has a preferably zigzag-shaped baffle 38, which opens into the open air at the free end faces of the heat exchanger and which, with its free, triangular opening cross-sections, runs transversely to the longitudinal channels 24 of the respective first component 12. This baffle 38 generally serves to guide the flow of cooling air; however, it is also conceivable to pass another gaseous or liquid cooling medium through it if necessary.

[0028] To complete the heat exchanger, it is further provided that the fourth component 40, which is arranged at the top and bottom in the stacking sequence, is each formed from a flat end plate, the upper one of which has the inlet and the lower one the outlet (not shown) for one medium, for example in the form of hydraulic medium. The respective inlet 42 or outlet 44 is formed from a separate cylindrical connecting piece 46, which is placed on one free side of the end plate and firmly connected to it via an annular weld seam 48. Instead of a weld seam 48, a soldered seam could also be provided, but this is so visually inconspicuous that it would no longer be recognizable in the drawing. Thus, in Figure 3, when soldered seam connections are used, the individual connection points are no longer recognizable.For attaching the corresponding connecting piece 46, a cylindrical through-opening 50 is provided in the plate-shaped fourth component 40, which is positioned in fluid-conducting alignment with the underlying front channel section 20 of the second component 14. A solder layer is applied to the underside of the upper, fourth component 40 and to the top side of the lower, fourth component 40; when heated, this solder layer forms a connection with the underlying or overlying second component 14.

[0029] The second embodiment according to Figures 3 to 5 will only be explained insofar as it differs significantly from the preceding embodiment, the same components being numbered with the same reference numerals and the statements made in this regard also applying to the modified embodiment.

[0030] In the solution according to Figure 3, the first component 12 arranged above the second component 14 is closed at the bottom, with respect to its front channel section 20, by a closure plate 52, which is preferably a component of the third component 16, wherein the closure plate 52 then covers the associated front channel section 20 of the second component 14. In this way, according to the arrow, the flow is deflected at a right angle by the closure plate 52 and flows through the individual flow guide channels 24 in a parallel orientation. At the end of the flow guide channels 24, the first and second components 12, 14 then flow through the rear channel sections 20, with the media flow subsequently deflected at a right angle by the closure plate 52 between the underlying first component 12 and second component 14.Now in the opposite flow direction, the flow guide channels 24 within the first component 12 are again flowed through from right to left as viewed in Figure 3, and at the end, via associated channel sections 20 of the fluid-carrying channel 18 formed in this way, the cooled medium passes through the outlet 44 from the heat exchanger, which is shown in the assembled state in Figure 5. While the individual channel sections 20 in the embodiment according to Figures 1 and 2 are essentially rectangular, they are essentially square in the solution according to Figures 3 to 5. In particular, the box height for the channel sections 20 of the second component 14 is such that they lie flush with the zigzag-shaped configuration of the guide plate 38.

[0031] As can be seen in particular from Figure 4, the frame 22 for the first component 12 is again constructed from individual segments, now with two opposing longitudinal bars or ledges 36, to which the frame-shaped channel sections 20 adjoin at the ends, once on the right side to form a continuous fluid-carrying channel 18; once on the left side closed by the end plate 52. However, it is also possible to produce the frame-shaped enclosure for the channel sections 20 and the two longitudinal bars or ledges 36 as shown in Figure 4 by means of a single frame 22 in a single piece (not shown) using a die-casting or injection-molding process.In all representations of the stack assembly 10, for the sake of simplicity, the third components 16 are not explicitly shown due to the thin-walled plate design; nevertheless, they always run between the first and second components 12, 14 and between the second and the subsequent first component 14, 12 in order to create a secure brazed connection between the individual plates of the heat exchanger. With the heat exchanger solution according to the invention, a wide variety of heat exchanger designs can be achieved in the sense of a modular system, as shown by way of example in DE 10 2014 001 703 A1. The cross-flow heat exchanger as a whole can preferably be manufactured in a single brazing process cut, whereby a fluid-tight connection is created between individual strips 36 and the frames 22 using the same brazing process as used in the manufacture of the heat exchanger.

Claims

Patent claims 1. Cross-flow heat exchanger in plate and strip construction, consisting of a plurality of individual components (12, 14, 16) which form a stack (10) with one another, with at least a first component (12) which enables a fluid passage of a medium in one direction, a second component (14) which enables a fluid passage of this or another medium in a further direction, a third component (16) which is arranged between the first (12) and the second (14) component and creates a fixed connection between them, and fluid-carrying channels (18) which at least partially pass through the stack (10) at the end and of which at least one channel section (20) serves to supply the medium for the first component (12) and another channel section (20) serves to remove the medium.

2. Cross-flow heat exchanger according to claim 1, characterized in that the first component (12) is enclosed on the outer circumference by a frame (22), the overall height of which corresponds to the overall height of at least one flow guide channel (24) which extends in a fluid-conducting manner between two channel sections (20) adjacent to said channel sections, which are at least partially enclosed by said frame (22).

3. Cross-flow heat exchanger according to claim 1 or 2, characterized in that the frame (22) is formed in one piece throughout, or is composed of individual strip-shaped frame parts (28) which, when adjacent to one another, leave a corner region (30) free.

4. Cross-flow heat exchanger according to one of the preceding claims, characterized in that the components (14, 16) adjacent to the frame parts (28) in the stack assembly (10) have a contour recess (32) following the respective corner region (30).

5. Cross-flow heat exchanger according to one of the preceding claims, characterized in that the corner regions (30) and contour recesses (32) arranged one above the other in the stacking sequence form an engagement possibility for a rod-like assembly aid and / or serve to introduce a weld seam (34).

6. Cross-flow heat exchanger according to one of the preceding claims, characterized in that the third component (16) is formed from a flat plate which has recesses in the size of the adjacent channel sections (20) and which is coated with solderable materials.

7. Cross-flow heat exchanger according to one of the preceding claims, characterized in that the fourth component (40) arranged at the top and bottom in the stacking sequence is each formed from a flat end plate, at least one of which has the inlet (42) and / or outlet (44) for the one medium, which is formed from a separate connecting piece (46) which is placed on one side of the end plate and is firmly connected to it.

8. Cross-flow heat exchanger according to one of the preceding claims, characterized in that the free cross sections for the individual channel sections (20) are rectangular, preferably square.

9. Cross-flow heat exchanger according to one of the preceding claims, characterized in that when using a plurality of flow guide channels (24) for the one medium, these are each formed from a longitudinal channel which extends from a channel section (20) at one end to the opposite channel section (20) at the other end.

10. Cross-flow heat exchanger according to one of the preceding claims, characterized in that the second component (14) has at least one guide plate (38) which opens into the open at the free end faces of the heat exchanger and which runs transversely to the flow guide channels (24) of the respective first component (12).

11. Cross-flow heat exchanger according to one of the preceding claims, characterized in that it can be manufactured in a single brazing process step.

12. Cross-flow heat exchanger according to one of the preceding claims, characterized in that a fluid-tight connection is created between individual strips (36) and the frames (22) by the same brazing process as used in the manufacture of the heat exchanger.

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