Heat exchanger

Abstract

The disclosure relates to a heat exchanger, for example an indirect air cooler, in which the air, for example compressed charge air for an internal combustion engine, is cooled, for example by a fluid, wherein the heat exchanger is constructed from stacked pairs of plates. The exemplary fluid can be conducted into an inlet region and/or outlet region of the plate pairs in at least one flow path approximately in the direction of the common edge, and further through at least a first duct approximately in cross current with respect to the exemplary air, and passes further through the plate pairs over the largest heat exchange area of the plate pairs approximately in countercurrent with respect to the air, in order to flow through at least one second duct, approximately in cross current with respect to the exemplary air, and back to the outlet.

Claims

1. A heat exchanger comprising: stacked pairs of plates arranged in a housing configured to direct a flow of a first fluid through fins arranged between the stacked pairs of plates in a first fluid direction, each one of the pairs of plates having: an inlet for receiving a second fluid; an outlet for expelling the second fluid; a flow barrier extending in the first fluid direction, the inlet and the outlet both being located between the flow barrier and a first lateral edge of the plates, the first lateral edge extending in the first fluid direction a first duct extending non-parallel with respect to the first lateral edge; a second duct extending non-parallel with respect to the first lateral edge; a heat transfer region bounded by the flow barrier and a second lateral edge of the plates opposite the first lateral edge and extending from the first duct to the second duct, wherein the heat transfer region has a larger heat exchange area than the first duct, the second duct, the inlet, and the outlet; an inlet region extending from the inlet to the first duct and bounded by the flow barrier and the first lateral edge; and an outlet region extending from the second duct to the outlet and bounded by the flow barrier and the first lateral edge, wherein the pairs of plates are configured such that the second fluid is conducted from the inlet, through the first duct in at least partial cross current with respect to the first fluid, further through the heat transfer region in countercurrent with respect to the first fluid, through the second duct in at least partial cross current with respect to the first fluid, and to the outlet.

2. The heat exchanger of claim 1, wherein the first and second ducts are disposed perpendicularly with respect to the first lateral edge.

3. The heat exchanger of claim 1, wherein each of the pairs of plates extends in a plane defining a longitudinal axis, wherein the longitudinal axis is perpendicular to the first lateral edge.

4. The heat exchanger of claim 1, wherein the first and second ducts are formed in inner edge regions of the pairs of plates and are parallel to each other.

5. The heat exchanger of claim 1, wherein the first and second ducts have a lower flow resistance than the heat transfer region.

6. The heat exchanger of claim 1, wherein the inlet region and the outlet region take up not more than 15% of an effective heat exchange area of the pairs of plates.

7. The heat exchanger of claim 6, wherein the inlet region and the outlet region take up between about 4% and about 12% of the effective heat exchange area.

8. The heat exchanger of claim 1, further comprising internal fins arranged in the heat transfer region of the pairs of plates.

9. The heat exchanger of claim 8, wherein the internal fins include corrugations having offset cutouts configured to permit the second fluid to flow alternatingly between the first fluid direction and transverse to the first fluid direction.

10. The heat exchanger of claim 9, wherein the corrugations extend in the first fluid direction, wherein the flow resistance in the first fluid direction is relatively higher than the flow resistance in a direction transverse to the first fluid direction.

11. The heat exchanger of claim 1, wherein the flow barrier is at least partially formed from at least one of a bead or an inserted rod.

12. The heat exchanger of claim 1, wherein the pairs of plates include a cutout disposed between the inlet and the outlet.

13. The heat exchanger of claim 1, wherein the inlet and the outlet include substantially elongated holes formed in the direction of the first lateral edge, the elongated holes abutting the first and second ducts, respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a perspective view of the heat exchanger (illustrated without a housing).

(2) FIG. 2 shows a similarly perspective view with a cover plate on the stack of plate pairs and fins.

(3) FIG. 3 shows a stack made of plates and fins in which the one plate of the upper plate pair has been removed in order to make the interior of this plate pair visible.

(4) FIGS. 4 and 5 show two plates which form a plate pair.

(5) FIG. 6 shows a perspective view of a plate part with an internal fin.

(6) FIG. 7 shows a view of the heat exchanger in a suitable housing.

(7) FIGS. 8 and 9 show modified plate configurations.

DETAILED DESCRIPTION

(8) In the perspective illustration (FIG. 1) of the heat exchanger, which is an indirect air cooler in the exemplary embodiment, the inlet 4 and the outlet 5 are located at the right-hand edges of metallic plates 1, which therefore represent the common edges E here. The inlet 4 is arranged at the end remote from the air inflow side AAir of the heat exchanger. The outlet 5 is, on the other hand, located closer to the inflow side of the charge air which is indicated by three block arrows. The inlet and outlet connectors have the reference symbols 40 and 50. The inlet and outlet cross sections have a circular shape in these embodiments. Instead of charge air, a mixture of charge air and exhaust gas or pure exhaust of an internal combustion engine (not shown) can also be present.

(9) An advantage of the disclosure worth mentioning is that the inlet 4 and the outlet 5 can be located on opposite edges which would then constitute the common edges E, without changing the throughflow, as a result of which structural restrictions can be coped with better than hitherto. In the exemplary embodiment shown, these edges E are the lateral edges of the plates 1. Two parallel longitudinal edges of the plates 1 are located approximately perpendicularly on the lateral edges, wherein the terms are used merely to differentiate between the edges, but do not in any case mean that the longitudinal edges, as shown in the exemplary embodiment, are longer than the lateral edges. The edges can all have the same length. The lateral edges can also be longer than the longitudinal edges. The fact that the edges in the exemplary embodiment shown are straight and therefore approximately rectangular plates 1 are present is also not an important precondition for solving the stated problem. The edges can also be arcuate or embodied in some other way which deviates from a straight line.

(10) In the exemplary embodiment shown, the plates 1 have a cutout 8 at the common edge E which is the right-hand lateral edge in FIG. 1. The depth of the cutout 8 is somewhat smaller than the depth of the inlet and outlet region 10. The position of the inlets and outlets 4, 5 is situated approximately in the center between the central longitudinal axis 15 of the plates 1 and their longitudinal edges. The inlet-side flow paths 11 extend from the inlets to the first ducts 12, which are arranged in the inner edge region of the one longitudinal edge in the plate pairs 1a, 1b. In the inner edge region of the other longitudinal edge there is the at least one second duct 13 which leads to the outlet-side flow path 11 and further to the outlet 5.

(11) In the exemplary embodiment shown, the ducts 12, 13 have the same cross section throughout. The ducts 12, 13 have a low flow resistance, that is to say at least a partial cross section of the ducts 12, 13 does not have flow impediments or the like. Since, as mentioned, approximately rectangular plates are present in the exemplary embodiment shown, the flow paths 11 and the ducts 12, 13 are also located approximately perpendicularly with respect to one another.

(12) In embodiments (not shown), the inlets and outlets 4, 5 are also arranged at a common edge E but in the vicinity of the corners of the plates 1 here, with the result that the lengths of the flow paths 11 becomes virtually zero. In other words, fluid can enter virtually directly into the first ducts 12 and virtually directly enter the outlets 5 from the second ducts 13. There would also be no reason, for example, not to arrange the inlets 4 in the corners and merely to position the outlets 5 approximately as shown, or vice versa. As a result, only significantly pronounced outlet-side flow paths 11 would be present while the length of the inlet-side flow paths 11 would approach zero, that is to say would be virtually invisible. The designer therefore has multiple options available for adapting the heat exchanger to restrictions forced on him by the installation location, without having to accept a loss of power.

(13) The flow paths 11 are preferably implemented by construction of beads in the plates 1 forming the pairs, as is apparent from the illustrations according to FIGS. 4 and 5. Instead of beads, rods which are inserted and soldered (or braised or welded) in the plate pairs can also be provided. In the exemplary embodiment shown, the beads or the rods form the flow barriers 6 mentioned above. These figures show plan views of the two plates 1 which form a plate pair 1a, 1b, with an internal fin 14 which is inserted therein, but is not illustrated in detail here.

(14) The plate 1b shown in FIG. 5 is rotated through 180 about its longitudinal axis 15 and is positioned on the plate 1a in FIG. 4. The two beads come to bear one against the other in the plate pair 1a, 1b and are connected later. They accordingly have a height which is approximately half as large as the distance between the two plates 1 which form the plate pair 1a, 1b. The height of the internal fin 14 must correspond to this distance. In addition, the plates 1a and 1b come to bear one against the other with their edges and are connected to one another in a sealed fashion. In the exemplary embodiment they are bent-over edges.

(15) Various other edge configurations are known from the prior art. These can alternatively be provided.

(16) The inlet and outlet openings 4, 5 of the plate pair 1a, 1b are provided with collars 41, 51 which protrude upward at the upper plate 1a and downward at the lower plate 1b. The connection to the adjacent plate pairs 1a, 1b takes place at these collars. Sealing rings which are located between the plate pairs and connect the latter are also an alternative to such collars 41, 51. In embodiments which are not shown just one of the plates 1 has a bead whose height has to be correspondingly larger, that is to say which should correspond to the height of the internal fin 14. Of course, the entire stack, that is to say the plate pairs and the fins 2 located therebetween are connected to one another, preferably connected metallically, for example soldered (or braised or welded) in a soldering (or braising or welding) oven. The soldered-in (or braised-in or welded-in) internal fin 14 through which the fluid flows is located within each plate pair 1a, 1b.

(17) Since the aforementioned internal fin 14 can have a smaller dimension than the plate 1 in which it is inserted owing to construction of the ducts 12, 13, the position of the internal fin 14 is indeterminate, which is disadvantageous. A correct position of the internal fin 14 the plate 1 can be implemented by virtue of the fact that inwardly protruding knobs or similar shaped elements 16 are formed in the corners of the plates 1 and serve as a stop for the internal fin 14. As a result, the preassembly of the heat exchanger improves. With this measure it is also possible to prevent an undesired bypass for the fluid, or at least largely suppress it.

(18) In FIGS. 3, 4 and 5, the inlet and outlet region which has already been mentioned is provided with the reference symbol 10. It makes up approximately 12% of the entire heat exchanging area here. Since this region for exchanging heat cannot contribute very much, the aim is to make it as small as possible. In FIG. 3, two arrows indicate that the corrugated internal fin 14 is preferably inserted into the plate pair 1a, 1b in such a way that when there is a flow through them in the longitudinal direction a significantly lower pressure loss dp occurs than when there is a throughflow in the lateral direction. The fluid is forced by the special design to take the path in the lateral direction and accordingly to flow though the plate pairs 1a, 1b in countercurrent with respect to the AAir.

(19) FIG. 6 shows, in a section, a perspective view of the corrugated internal fin 14 which is located in the plate 1. Some details of the corrugated internal fin 14 can be seen. The direction in which the corrugation runs in the heat exchanger is the lateral direction thereof, that is to say the direction of the significantly higher pressure loss dp. In the corrugation edges 17 there are breakthroughs or cutouts 18 offset alternately to the left and to the right when viewed in the direction of said corrugation edge 17. The width of the ducts 12, 13 is determined by the distal end of the flow barrier 6 and the longitudinal edge of the plate. As is also shown by FIG. 6, a narrow strip of the duct 12 is completely free.

(20) In embodiments according to the disclosure (not shown) the entire duct 12, 13 is of free design. In other embodiments (not shown) the longitudinal edge of the internal fin 14 extends directly to the longitudinal edge of the plates 1, with the result that the entire duct cross section is occupied by a section of the internal fin 14. The function of the ducts 12, 13 is retained because the aforementioned section points in the direction of the low pressure loss dp which corresponds to the direction of the duct. There is also the possibility of covering the cross section of the one duct completely with part of the internal fin 14 and leaving the other duct completely free.

(21) As is also the case in known heat exchangers, the compressed charge air AAir to be cooled flows through an opening into a housing 3 in which the aforementioned stack made of plate pairs 1a, 1b and fins 2 (not illustrated in more detail) are located (FIG. 7). The housing 3 can be the intake manifold of an internal combustion engine. According to the proposal, the charge air then flows through the corrugated fins 2 in countercurrent with respect to the fluid flowing in the plate pairs, and in the process it is cooled extremely efficiently. The direction of flow of the charge air is, also according to the proposal, provided in the direction of the common edge E at which the inlet 4 and the outlet 5 for the fluid are located, or in the exemplary embodiment in the direction of the lateral edges of the plates 1. As a result, the cooled charge air leaves the heat exchanger through another opening in the housing 3 in order to be available for charging the internal combustion engine (not shown). The protruding edge 9.1, of the cover plate 9 which can be seen in FIG. 2 and which terminates the stack and is connected metallically thereto, for example, can be used in a known fashion to attach the plate stack in the housing 3 and therefore serves as a closure of an assembly opening in the housing 3.

(22) FIG. 8 shows a plate 1 with elongate holes as inlets and outlets 4, 5. The flow paths 11 have been virtually integrated into the elongate holes since there to a certain extent a flow guide is formed in the direction of the common edge E, as is also the case with the flow paths of the other exemplary embodiments. In embodiments which are not shown, the inlets and outlet 4, 5 have other different hole shapes. These may also include hole shapes which are configured asymmetrically. FIG. 9 in turn shows round plate holes 4, 5 but modified flow barriers 6.