Improved modular heat exchanger

Abstract

A plate (19) according to the invention comprises: - a first side (19e) which is coated with an electrically insulating layer (2), wherein an electrical conductor (17) is applied to or embedded in the electrically insulating layer (18); and - a second side (19z) on which elevations (15, 16) are provided. A coolable resistor (W) can be constructed from plate pairs (B) and from corresponding seals (C). It is compact and efficient and individual plate pairs can be easily exchanged.

Description

[0001] DESCRIPTION

[0002] Improved modular heat exchanger

[0003] The present application relates to a plate and pairs of plates that can be connected together to form a coolable resistor. In particular, such a resistor is used for a braking resistor.

[0004] Particularly in the field of drive technology, especially in commercial vehicles, excess braking energy can be converted into braking resistors. The vehicle's kinetic energy is converted into electrical energy, for example, by a generator brake (drive motor in recuperation mode). If this energy cannot be used elsewhere (e.g., stored in a battery), it is converted into a liquid-cooled braking resistor. The resistor acts as a consumer, converting electrical energy into heat. This heat must then be dissipated accordingly to prevent the braking resistor from overheating.

[0005] Document DE 10 2021 202 037.4 discloses a fluid-operated braking resistor constructed from multiple shaped sheets. The shaped sheets have a first side and a second side, and two shaped sheets are connected to each other at the edges by beads, for example, by welding.

[0006] On the other side, an electrically conductive device is provided which is embedded in an insulating layer, which generates the heat - on the other side, the heat is then dissipated, since a flow path is defined here through which a coolant can flow.

[0007] Connecting two formed sheets using beads (especially beads at the edge of the formed sheets, such as circumferential beads) can be problematic, especially if the beads protrude in one direction. The electrically conductive layer can be applied using a screen printing process; in this case, it is important that planar surfaces are present so that the printed areas can be printed evenly.

[0008] Furthermore, the use of protruding beads does not allow for a very compact design, so that when several shaped sheets are stacked on top of each other, considerable space is required.

[0009] It is therefore an object of the present invention to provide shaped sheets with a coolable resistor, in which printing of the shaped sheets is possible without problems and in which the space requirement can be reduced as far as possible.

[0010] The object is achieved by a plate according to claim 1, a pair of plates according to claim 8 and a coolable resistor according to claim 9. Further advantageous embodiments of the present invention are the subject of the dependent claims.

[0011] A plate according to the invention has: a first side which is coated with an electrically insulating layer, wherein an electrical conductor is applied to the electrically insulating layer and is embedded therein. Furthermore, the plate has a second side on which elevations are provided.

[0012] The plate is designed to be part of a coolable resistor or a coolable resistor unit.

[0013] The elevations are embossed into the plate as projections. When two plates are in contact, these projections are in contact with the opposite projection of the plate and are joined, for example, by laser welding. Multiple projections can form contact points during welding.

[0014] This enables the formation of flow channels. The raised portion also contributes to load transfer, which can minimize plate deformation, for example, initiated by coolant pressure. Furthermore, the raised portions increase the degree of turbulence and thus improve heat transfer into the coolant. Numerical simulations have shown that heat transfer can be increased by 15% compared to conventional beads.

[0015] Furthermore, there is no need to divert the flow, which avoids dead spaces and thus improves heat transfer.

[0016] Preferably, a groove is provided on one edge of the first side (more preferably running along the edge), which is adapted to receive the edge portion of a seal. This has the advantage that two first sides of two opposing plates do not need to be cast, as was the case in the prior art, but rather that they can be releasably connected to one another by a seal. The edge of the plates is also used to join the two plates on the second side by laser welding.

[0017] Preferably, the electrical conductor is arranged between elevations (the electrical conductor is arranged on the first side of the plate – the elevations on the second side of the plate are therefore formed as depressions or dents here – however, the term "elevation" has been used consistently). Further preferably, it is arranged in a meandering pattern around elevations (or depressions / dents). This way, the electrical conductor is very close to the elevations (or depressions / dents), a long length of the electrical conductor can be accommodated, and the electrical conductor also has a very large surface area, which further increases heat transfer.

[0018] Preferably, electrical contact surfaces are provided at each end of the electrical conductor, each of which is adapted to be contacted by a spring element. This can be connected to the connection plug through which the electrical current is introduced to the plate. Here, soldering of connection plugs, etc., can be omitted, which minimizes manufacturing costs. The contact surfaces are preferably printed and provided with an additional foil (by means of a soldering process) in order to use the foil as a sacrificial layer with regard to abrasion of the spring contact. A plate according to the invention further preferably has at least one, preferably two openings, wherein (further) elevations are further preferably provided around the openings on the second side of the plate. These elevations serve to stabilize the openings, so that no deformation due to fluid occurs here.Furthermore, a contact pressure is generated for the seals, which further improves the tightness.

[0019] The elevations are preferably point-shaped, cylindrical, or hemispherical, making them easy to emboss into the plate. Furthermore, this allows for the formation of a transient wake zone, which ensures heat dissipation in the wake area. Contours with a sharp edge, on the other hand, would create larger, stationary wake zones, which would prevent heat dissipation.

[0020] A plate pair comprises two plates in which the second sides of two plates are arranged opposite each other. The edges of the second sides of two plates are tightly connected to each other, preferably by a weld.

[0021] The raised portions on the other side of two plates are also connected (e.g., welded, i.e., spot weld, weld seam), thus creating smaller flow channels. The incoming coolant is distributed evenly within the gap between the two plates, enabling homogeneous heat dissipation.

[0022] This allows for the formation of a stable unit, as the internal pressure forces can be dissipated by the inflow of the fluid, thus resulting in minimal deformation. This minimizes the stress on the electrically insulating layer. Furthermore, the flow cross-section of the flow channels remains unchanged and does not bulge. The large heat exchanger surfaces are largely made possible by the plate-based design. However, the plate structure can be susceptible to deformation due to the internal pressure of the coolant. Load transfer is ensured by the elevations and their connection to the opposing plate. Preferably, a plurality of coolable resistor units and seals are provided, and one seal is always arranged between two coolable resistor units (the coolable resistor units and seal are stacked one on top of the other).A cover plate is provided as the outer boundary of each coolable resistor (a first side of a plate is in contact with the cover plate, but in this case is not provided with an electrical conductor), with all plate pairs and the connection plates being connected to one another with a fixing element. This fixing element is preferably a screw. This fixing element allows all coolable resistor units and all seals to be pressed together, resulting in a compact and, above all, leak-proof design. At the same time, however, the fixing element can be removed again if, for example, a plate pair (a coolable resistor unit) needs to be replaced due to a defect or a leak.

[0023] This makes it very easy to stack any number of plate pairs on top of each other; the number can be varied depending on the power requirements of the coolable resistor. The seals prevent liquid from penetrating parts with electrical conductors. The raised portions in the plates also serve to transfer the load of the seals, particularly those arranged around openings. Plastic deformation of the sheet metal structure can thus be prevented. The seal preferably has an edge section that can engage with the grooves on two opposite first sides of the plates of the plate pairs. This would ensure a particularly efficient sealing effect.

[0024] The coolable resistor preferably has at least one inlet and one outlet, each provided in a cover plate. A hydraulic connection is also preferably provided here. All openings are then arranged one below the other and form a first collecting area, and all second openings are also arranged one below the other and form a second collecting area. The inlet and the outlet are either connected to the first collecting area (or a section thereof) or to the second collecting area (or a section thereof), or are divided between both collecting areas - i.e., the first collecting area is connected to the inlet and the second collecting area to the outlet, or vice versa. The collecting areas can be divided into several sections by closed plates.

[0025] Further preferably, at least one of the first openings below the second opening of a coolable resistance unit is closed, while fluid can still flow from the inlet to the outlet. This makes it possible to connect a certain number of coolable resistance units in parallel or series, depending on the specific requirements. This can be arranged very flexibly without requiring major modifications to the individual elements – all that is required is to close some of the first openings and some of the second openings of the coolable resistance units in the overall system.

[0026] The closed first and second openings serve to connect some of the existing coolable resistance units in parallel and others in series, thus directing the cooling fluid accordingly. Both collection areas can thus be subdivided. This allows a certain number of coolable resistance units to be connected in parallel or in series, depending on the specific requirements. Furthermore, the variable arrangement of the connections also allows for a gradual increase in flow velocity (by reducing the number of plates in the parallel-connected segments), which serves to improve heat transfer and compensate for the preheating of the coolant.

[0027] The connection of the coolable resistance elements is deliberately designed for parallel connection in order to:

[0028] - Minimize the individual currents at the spring contacts

[0029] - To make the specific load per plate dependent on the coolant temperature. The plates that are fluidically aligned with the inlet are subjected to greater load (due to the lower coolant temperature, which causes a lower conductor temperature, which in turn results in a lower resistance value). The relatively lower resistance value at the inlet compared to the outlet leads to a higher current flow, which is expressed as I 2 is included in the power calculation. Or the last coolable resistance element on the flow side is subjected to lower power

[0030] In the following, embodiments of the present invention are explained in more detail with reference to the accompanying figures.

[0031] Fig. 1 shows a first side of a plate for a coolable resistance element according to a first embodiment of the present invention.

[0032] Fig. 2 shows a second side of a plate for a coolable resistance element according to a first embodiment of the present invention.

[0033] Fig. 3 shows a seal adapted to be arranged between two pairs of plates.

[0034] Fig. 4 shows a pair of plates (coolable resistance element).

[0035] Fig. 5 shows a seal between the two pairs of plates in cross-sectional view.

[0036] Fig. 6 shows a seal between the two pairs of plates in cross-sectional view, showing in particular the spring contact of the conductors.

[0037] Fig. 7 shows an isometric view of two pairs of plates between which a seal is arranged.

[0038] Fig. 8 shows a cross-sectional view through a coolable resistor according to the invention.

[0039] Fig. 9 shows an external view of a coolable resistor.

[0040] Fig. 1 shows the first side 19e of a plate 19. This plate 19 has a generally hexagonal shape (essentially consisting of two triangles and a rectangle), with an elongated part and a shorter part. A first opening 25a and a second opening 25b are provided at each end of the elongated part. These openings are at least partially surrounded by a plurality of second elevations 16, which, however, extend toward the second side 19z (not shown here)—i.e., the rear side. On the first side 19e, the second elevations 16 therefore have the shape of embossed depressions. A groove 23 is provided at the edge of the plate 19, in which a seal (not shown here) can be arranged. Furthermore, a plurality of first elevations 15 are distributed over the surface (in particular, the rectangular, elongated part) of the first side 19e, which also extend toward the second side 19z (not shown here) of the plate 19.On the first side 19e, the first elevations 15 therefore also have the shape of depressions. An electrical conductor 17 extends between the first elevations 15. This is arranged on an electrically insulating layer 18 that was previously applied to the first side 19e of the plate 19 - and is printed, for example, by a screen printing process. The electrical conductor 17 also has two electrical contact surfaces 13 on the first surface 19e. The electrical conductor 17 is arranged in a meandering shape around the first elevations 15. The electrical conductor 17 thus has the largest possible surface area. Arrows 21 also indicate the flow direction of a fluid, which serves for cooling, but which flows on the second side 19z (not shown here) of the plate 19.Here, it is clearly visible that the flow direction of the fluid is orthogonal to the main direction of the electrical conductor 17 (the direction in which the electrical conductor 17 primarily extends). At both outermost points (the apex of the triangles of the hexagon), receiving sections 26 are provided, here in the form of semicircular recesses. These serve to clamp several plates 19 using a fixing element 7 (not shown here), for example, a screw.

[0041] This allows the coolant to move from zones with thermal stress to zones without. This greatly minimizes the thermodynamically swept contact length and prevents overheating.

[0042] Fig. 2 shows a second side 19z of the plate 19 - i.e. the back of the first side

[0043] 19e (not shown here) – this is the side where the coolant flows. The first opening 25a and the second opening 25b are visible again, as are the first elevations 15 and the second elevations 16.

[0044] At the edge of the plate, a connecting area 27 is provided, where two plates 19 can be welded together (with opposing second sides 19z). The first elevations 15 are distributed across the cross-section of the plate, and several second elevations 16 are located around the first opening 25a and the second opening 25b. The first elevations 15 and second elevations 16 are each point-shaped or hemispherical. The receiving sections 26 can also be seen here in Fig. 2.

[0045] Fig. 3 shows a sealing element C which essentially follows the hexagonal cross-section of a plate 19 (not shown). The sealing element C consists of an outer section C1 which essentially follows the hexagonal shape of the plate, and two inner sections C2 which extend inwards from the outer corners of the hexagon and have a round shape. The outer section C1 is intended to seal the outer edge between two plates 19 (not shown here), and the inner sections C2 are intended to seal a first opening 25a and a second opening 25b (not shown here), respectively. Spring contacts 12 are arranged inwards on one long side of the sealing element C. These spring contacts extend upwards and downwards and are therefore suitable for contacting two electrical contact surfaces 13 (not shown here) which are arranged above and below the sealing element C.An electrical connection 11 is provided on the other side of the spring contact 12. The combination of electrical connection 11 and spring contact 12 can be molded into the sealing element C, but can also simply be pushed through it.

[0046] Furthermore, in the area of ​​the two inner sections C2, a protruding section C3 is present - this serves to ensure that this area can be pressed particularly firmly and elastically deformed, which leads to a better seal in the area of ​​the first and second openings 25a and 25b (not shown here), which carry liquid accordingly.

[0047] Fig. 4 shows a cross section along the line A of Fig. 1 , here the interior

[0048] 20 when two plates 19 are arranged next to one another (two first sides 19e are opposite one another here). This creates a region 20 through which liquid can flow. Furthermore, welding contact points 14 are shown here; in other words, the first elevations 15 (not shown here) of two second surfaces 19z of the plates 19 are welded together. To prevent one-sided bending due to printing, the two plates 19 are first welded together and then alternately printed with the electrical conductor 17 (not shown in Fig. 4). Due to the alternating pressure, the stresses equalize and the plates 19 remain flat.

[0049] Fig. 5 primarily shows the sealing element C. Here, it is shown that an outer section C1 of the sealing element C engages with the groove 23 shown in Fig. 1 on the first side 19e of the plate 19. Furthermore, the sealing region 22 is shown, which in particular seals a first collection region 9a or second collection region 9b through which coolant (e.g., liquid) flows. This is essentially sealed by the inner section C2 of the sealing element C. The forces acting on the sealing element C are indicated by the reference symbol F.

[0050] Fig. 6 shows two plate pairs B (consisting of two plates 19), between which a sealing element C is arranged. It can again be seen that forces F act on the plate pairs B. In the sealing element C, spring contacts 12 are shown for electrically contacting the electrical contact surfaces 13 of the plate pairs B. Furthermore, an electrical connection 11 is provided here, which is electrically connected to the spring contacts 12. Furthermore, welding contact points 14 are shown here; here, the first elevations 15 (not shown here) of two second surfaces 19z of the plates 19 are welded together.

[0051] By pressing two pairs of plates B and a seal C together, a tight connection is created such that no liquid can flow along the second surfaces 19z (not shown here) in the area of ​​the electrical conductor 17 (not shown here). Fig. 7 shows an isometric view of two pairs of plates B, between which a seal C is located. Furthermore, the electrical connections 11 are shown here, which are connected to the spring contacts 12 (only partially shown here). A sealing element C is arranged between two pairs of plates B - in a stacked arrangement. The first side 19e of a plate can be seen at the top - with a meander-shaped electrical conductor 17 and electrical contact surface 13. The first opening 25 and the second opening 25b are also visible.

[0052] Fig. 8 shows a resistance device A (a liquid-cooled resistor). This contains several coolable resistance elements B (not all labeled in detail here). A pair of plates is therefore a coolable resistance element, as it is the smallest unit of a coolable resistor. A closure plate 6 is provided at the top and bottom. An inlet 5 is provided at the top of the upper closure plate 6, and an outlet 5' is provided at the bottom of the lower closure plate 6. Furthermore, it is shown that a hydraulic connection 8 is present in the inlet 5 and the outlet 5', which is provided in the quick-connect system. Furthermore, the flow pattern is clearly visible, as closed plates 10 are provided at regular intervals at openings on the left side, as well as on the right side. A first collection area 9a is provided on the left (this is divided into three sections 9a', 9a", and 9a'") by closed plates 10.When coolant enters the first section 9a' through the inlet 5, it flows through several coolable resistance elements B in parallel. A collection area 9b (divided into sections 9b', 9b") is provided in the right-hand area. Here, too, a closed plate 10 is provided for subdivision. The coolant then reaches section 9b' of the second collection area 9b. Here, a certain number of coolable resistance elements B can again flow through in parallel until the first collection area 9a (now section 9a") is reached. Here, a closed plate 10 is again provided at a certain distance, so that the fluid is again deflected to the right (until it reaches section 9b" of the second collection area 9b) - from there, it is deflected again to the left until it reaches section 9a'" of the first collection area 9a, so that it can flow out through the outlet 5'.By providing closed plates 10, any number of parallel or almost parallel flowing plate pairs B can be provided, so that the resistance device A can be variably adjusted to specific cooling capacities.

[0053] Fig. 9 shows an isometric view of a resistance device A. It also shows a terminal box 4, to which dampers 2 for mounting and connecting cables 1 are provided. Hydraulic connections 8 are also shown.

[0054] The present invention is not limited to the above-mentioned embodiments.

[0055] The geometry of the plates 19 can be arbitrary; it does not have to be hexagonal. Furthermore, flow channels can be implemented in a variety of ways; connections or openings are not necessarily required on two opposite sides of the hexagon.

[0056] LIST OF REFERENCE SYMBOLS

[0057] A resistance device

[0058] B Pair of plates I Coolable resistance element

[0059] C Sealing element (with contacts)

[0060] C1 outer section

[0061] C2 inner section

[0062] C3 protruding section

[0063] F contact pressure

[0064] 1 connection cable (with EMC shield)

[0065] 2 dampers

[0066] 3 Contact protection

[0067] 4 junction box

[0068] 5 Entrance

[0069] 5' outlet

[0070] 6 End plate

[0071] 7 Fixing element / screw

[0072] 8 Hydraulic connection (Quick Connect)

[0073] 9a first collection area

[0074] 9a', 9a", 9a'" section

[0075] 9b second collection area

[0076] 9b', 9b" section

[0077] 10 closed plate

[0078] 11 electrical connection

[0079] 12 spring contact

[0080] 13 electrical contact surface

[0081] 14 Welding contact point

[0082] 15 first survey

[0083] 16 second survey

[0084] 17 electrical conductor 18 electrically insulating layer

[0085] 19 single plates

[0086] 19e first side of the single plate

[0087] 19z second side of the single plate 20 liquid flow area / interior area

[0088] 21 Flow direction

[0089] 22 Sealing area

[0090] 23 Groove (for indexing the seal)

[0091] 24 bead 25a first opening

[0092] 25b second opening

[0093] 26 Recording section

[0094] 27 Connection area

Claims

PATENT CLAIMS 1. Plate (19), comprising: a first side (19e) coated with an electrically insulating layer (2), wherein an electrical conductor (17) is applied to the electrically insulating layer (18) or embedded therein, and a second side (19z) on which elevations (15, 16) are provided.

2. Plate (19) according to claim 1, wherein on the first side (19e) at the edge a groove (23) is provided which is adapted to receive the edge portion (C1) of a seal (C), 3. Plate (19) according to claim 1 or 2, wherein the electrical conductor (17) is arranged between the regions in which elevations (15, 16) are provided, and preferably in a meandering manner around the regions in which elevations (15, 16) are provided.

4. Plate (19) according to one of the preceding claims, wherein electrical contact surfaces (13) are provided at the ends of the electrical conductor (17), which are adapted to be contacted by a spring element (12) which is preferably provided in a seal (C).

5. Plate (19) according to one of the preceding claims, which further comprises at least one, preferably two, openings (25a, 25b), wherein elevations (16) are preferably provided around the opening(s) (25a, 25b) on the second side (19z) of the plate (19).

6. Plate (19) according to one of the preceding claims, wherein the elevations (15, 16) are point-shaped, cylindrical or hemispherical.

7. Pair of plates (B) consisting of two plates (19) according to one of the preceding claims, wherein the respective second side (19e, 19e) of the two plates (19, 19) are arranged opposite each other, wherein the edges of the second side (19e) of the two plates (19, 19) are tightly connected to one another, preferably by a weld.

8. Pair of plates (B) according to claim 7, wherein the elevations (15, 16) are each connected to one another, preferably by a weld spot or a weld seam.

9. Coolable resistor (W), comprising at least two plate pairs (B) according to claim 8, wherein a seal (C) is provided between two stacked plate pairs (B), the outer side of which represents the first side (19e) of the plates (9), wherein an end plate (6) is provided as the outer boundary, wherein all plate pairs (B) and the two connection plates (6) are connected to one another by a fixing element (7), wherein the fixing element (7) is preferably a screw.

10. Coolable resistor (W) according to claim 9, when dependent on claim 2, wherein the edge portion (C1) of the seal (C) engages with the grooves (23) of two opposite first sides (19e) of plates (19) of the plate pairs (B).

11. Coolable resistor (W) according to claim 9 or 10, further comprising at least one inlet (5) and outlet (5'), which are each provided in a cover plate (6), wherein all first openings (25a) are arranged one below the other and form a first collecting area (9a), and all second openings (25b) are arranged one below the other and form a second collecting area (9b), wherein the inlet (5) and the outlet (5') are connected either to the first collecting area (9a) or to a section (9a 1 , 9a", 9a'") thereof or the second collection area (9b) or a section (9b 1 , 9b") thereof, or are divided between both collection areas (9a, 9b).

12. Coolable resistor (W) according to claim 11, wherein at least one of the first openings (25a) and / or second openings (25b) is closed, whereby liquid can flow from the inlet (5) to the outlet (5').

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