Heat exchanger and heat exchanger arrangement with multiple heat exchangers

Abstract

Heat exchanger (10) with at least one plate (12) which can be attached to a battery module of an electric vehicle, wherein numerous at least partially parallel channels (14) for the evaporation of coolant are formed in a plane parallel to the plate (12) and are branched from at least one common inlet (16) and / or outlet (22), wherein at least one intermediate channel (20) which begins at a branch is branched again, and more than two intermediate channels (20) begin at at least one branch, characterized in that at least one flow guide element (26) is provided in at least one branch and that at least one flow guide element (26) is formed over the entire clear height of an inlet channel (18).

Description

Technical area

[0001] The invention relates to a heat exchanger with at least one plate which can be attached to a battery module of an electric vehicle as an object to be cooled, and to a heat exchanger arrangement with a plurality of heat exchangers. State of the art

[0002] Electric and hybrid vehicles have recently become increasingly popular in order to reduce fossil fuel consumption. However, the batteries of such vehicles require cooling under certain operating conditions. Temperature differences between individual battery cells must be kept as small as possible. Furthermore, the pressure loss within a cooler or dedicated heat exchanger should be kept as low as possible. At the same time, the overall stability of the heat exchanger must be kept in mind.

[0003] In heat exchangers for refrigerants and coolants, dimples are used as flow guidance and distribution elements to optimize flow. At the same time, this increases turbulence, which leads to an increase in the heat transfer coefficient from the fluid to a solid, such as a heat exchanger plate or a battery housing. In a heat exchanger for refrigerants, it is also important to note that heat absorption is particularly efficient during refrigerant evaporation, but there is no need to generate turbulence. With this approach, however, the heat exchanger must still be optimized with regard to heat transfer and packing density.

[0004] US 9 134 072 B2 relates to a heat exchanger designed for two fluids, in which the flow channels are multiply branched and intertwined. Further heat exchangers are also known from EP 2 149 771 A1, DE 11 2015 003 530 T5, EP 1 387 424 A2, and DE 10 2009 016 577 A1. Description of the invention

[0005] Against this background, the object of the invention is to create an optimized heat exchanger for heat transfer between a fluid and a solid body.

[0006] This object is achieved by the heat exchanger according to claim 1. Preferred embodiments are described in the subclaims

[0007] Accordingly, it has at least one plate, which is typically attachable to an object to be cooled, such as a rechargeable battery or a battery. Although the following partially refers to an object to be cooled, a rechargeable battery, or a battery in general, the heat exchanger according to the invention is particularly designed for use as a battery cooler and as a contact evaporator for coolants and, to this extent, can be attached in its entirety, preferably by means of its plate, to a battery module of an electric vehicle.

[0008] Here, numerous, at least partially parallel channels for the evaporation of refrigerant are formed in a plane parallel to the plate and branched from at least one common inlet and / or outlet. The parallel design to the plate essentially means that at least one boundary, visible in a cross-sectional view of the channel, is parallel to the plate surface and typically coincides with it. The opposite boundary, and thus the "height" of the channels above the plate plane, can also lie in the same plane for all channels. However, this is not necessarily required.

[0009] The channels typically become increasingly narrower downstream of any branching points (in a direction parallel to the plate plane), allowing a uniform flow velocity to be maintained. The opposite applies (increasing width) downstream of any channel junctions. The structure with multiple branches can be described as meander-like, tree-like, or vein-like. In this respect, the invention is based on the principles of bionics. The narrowing or widening applies to the channels in the flow direction before and after branches or junctions. The channels themselves preferably have a constant cross-sectional area throughout their course.

[0010] Furthermore, the channels can be designed with simple measures to withstand the necessary pressures and to achieve a low overall pressure loss. In particular, the heat exchanger according to the invention is designed for evaporation of the refrigerant, which can correspond to a refrigerant used in vehicle air conditioning systems. By designing the heat exchanger with a plate, it can be constructed in various sizes and / or in a modular manner and can be easily adapted to a wide variety of battery arrangements and requirements with regard to cooling capacity, acceptable pressure losses, etc. Furthermore, the heat exchanger according to the invention achieves a high packing density with low weight. Finally, a further advantage of the channel structure according to the invention is greater process reliability during the soldering process used to manufacture the plate.

[0011] Although it is conceivable in certain applications that each channel is branched only once, it offers advantages for the possible applications of the heat exchanger according to the invention if at least one channel, which in turn begins at a branch, is branched again.

[0012] In initial simulations, it has also been shown to be advantageous if at least one branch with more than two channels, in particular three or four channels, is provided.

[0013] Particularly in such a case, it has also proven advantageous to provide at least one flow guide element in at least one branch in order to improve the fluid flow in the direction of the channels emanating from the branch.

[0014] For such a flow guide element, it is preferred that it extends over the entire clear height of the flow channel to be branched. In other words, the flow channel is blocked over its entire height above the plate surface, so that the refrigerant encountering such a flow guide element is directed particularly reliably towards the flow channels downstream of the branch. The turbulence generated by the flow guide element supports this. Furthermore, such an interruption of the flow channel, or in other words a connection between the plate plane and the boundary of the flow channels in a plane spaced from the plate plane, supports the strength of the entire heat exchanger, so that it can withstand the loads occurring even at a refrigerant pressure of up to 20 bar.This effect is based on the fact that an area in the region of a branching, especially with more than two channels, can be reduced in size and stabilized.

[0015] In initial simulations, a flow guide element that is essentially round when viewed in a direction perpendicular to the plate plane has also proven to be advantageous.

[0016] As already mentioned, it offers advantages for design and manufacturability if all ducts have the same clear height above the panel plane. In other words, viewed in cross-section, the boundary remote from the panel plane lies in a common plane. In combination with this, the previously mentioned measure of varying the ducts in terms of their width across the panel plane is preferred.

[0017] In the case of two or more inlets and / or outlets, it is currently preferred that the channels connected to a common inlet or outlet be at least partially symmetrical to other channels connected to a different inlet or outlet. This ensures a particularly clear and efficient arrangement of the channels.

[0018] For the durability of the heat exchanger according to the invention, it is advantageous if the plate can withstand a pressure of at least 20 bar, preferably at least 60 bar. This is the bursting pressure of the plate and defines the safety margin between normal operation and bursting (failure).

[0019] It also offers advantages if at least two, preferably several, channels are locally connected along their course between the inlet and outlet to create a bypass and enable mixing between the individual channels. The connection of at least two parallel channels can be achieved by a suitable transverse punching or bead. Mixing between the fluid flows of at least two channels offers advantages in that the coolant in individual channels can have different temperatures and / or states of aggregation. In this respect, mixing ensures homogenization and improved cooling, for example, of a battery.

[0020] The same effect, namely an improvement in the thermal management of a battery, can be achieved by arranging the inlet and outlet in such a way that adjacent channels flow countercurrently. In other words, at least one channel with already superheated refrigerant is located next to a channel with evaporating refrigerant, so that heat transfer also occurs between two channels arranged in this way.

[0021] The subject of the application is also a heat exchanger arrangement with a plurality of heat exchangers in one of the previously described embodiments, which are connected in parallel and / or in series to one another and / or lie in a common plane or in parallel planes. Short description of the drawings

[0022] Preferred embodiments of the invention are explained in more detail below with reference to the figures. They show: Fig. 1 a plan view of a heat exchanger according to the invention; Fig. 2 a plan view of a section of a to the in Fig. 1 shown heat exchanger similar heat exchanger; Fig. 3 a plan view of a second embodiment of the heat exchanger according to the invention; and Fig. 4 a heat exchanger arrangement according to the invention. Detailed description of preferred embodiments of the invention

[0023] In Fig. Figure 1 shows the heat exchanger 10 according to the invention in a plan view of its plate 12, on which numerous channels 14 run largely parallel to one another. They originate from a common inlet 16, which is followed by an inlet channel 18. In the embodiment shown, this channel branches into four intermediate channels 20, and each of these intermediate channels 20 branches into two channels 14, which are not further branched but extend largely parallel to one another across the entire plate, including in the area of ​​deflections of, for example, 90° or 180°, before they merge upstream of an outlet 22, essentially corresponding to the situation at the inlet 16. In the embodiment shown, two channels 14 each merge to form an intermediate channel 20, and four intermediate channels 20 merge to form the outlet channel 24 leading to the outlet 22.

[0024] As shown in the illustration by Fig. 1, the numerous channels 14 can cover essentially the entire plate surface, so that no significant temperature differences are to be expected for several battery or accumulator cells that are arranged adjacent to one another in such a way that the plate 12 can be attached to several such cells.

[0025] In the embodiment shown, the inlet 16 and outlet 22 are located relatively close to each other and, in particular, approximately in the middle of one side of the plate. Furthermore, a preferred measure is shown, according to which the individual channels 14 are arranged over large areas to an axis of symmetry running transversely across the plate, in Fig. 1 from left to right, are symmetrical to each other. In addition, Fig. 1 in the form of the connection 28, the preferred measure is shown, according to which several, in the case shown all parallel channels are connected to each other in order to enable a mixing of the fluid flows. Finally, in Fig. 1 it is particularly clear that adjacent channels are flowed through in countercurrent. Utilizing the space available on the plate 12 shown, the refrigerant flows from the bottom right to the top right in the parallel channels on the outside of the plate, and after reversing by 180° in the top right area according to Fig. 1, it flows back in the inner area of ​​the plate, resulting in the countercurrent described above and the advantages mentioned. It should be noted that this applies equally, but to a somewhat lesser extent, to the embodiment of Fig. 3 applies. It should also be mentioned that the heat exchanger of Fig. 1 could also flow in the opposite direction, meaning first through the inside and then through the outside. This would have the advantage of keeping the comparatively cold coolant in the inner area and thus in the comparatively hot area of ​​a battery to be cooled.

[0026] In Fig. 2 shows the area with the branches between the inlet channel 18 and the individual channels 14, which in this case corresponds to the situation at the outlet 22, but with this shape could also be provided in the area of ​​the inlet 16. In the area of ​​the inlet, a flow guide element 26 is particularly important, which is located at the branching point of the inlet channel 18 onto the three intermediate channels 20 and ensures a favorable distribution to the intermediate channels 20. In the case shown, the flow guide element 26 is essentially circular in plan view and completely interrupts the flow channel. In other words, the upper boundary of the flow channels (facing towards the viewer) is aligned with the upper boundary (facing away from the viewer, cf. Fig. 1) Plate 12 is connected, creating a flow-blocking "dimple." In the illustrated case, this flow guide element is provided between the second and third intermediate channels 20, so that, as mentioned, a favorable distribution among all three intermediate channels 20 is achieved.

[0027] In Fig. 3 shows an alternative embodiment of the heat exchanger 10 according to the invention, in which two inlets 16 and two outlets 22 are provided. In this case, the flow channels that emanate from the inlet 16 merge to the edge (according to Fig. 3 the right edge) of plate 12, where they are again combined. From there, a connection can be made to the Fig. 3 return flow channels are present, which can be seen below, the inlet 16 of which is in Fig. 3 is located at the bottom right. Alternatively, the heat exchanger shown can be connected with its outlet 22 to other heat exchangers of an arrangement, as described in more detail below. Two of the Fig. The heat exchangers shown in Figure 3 can be provided essentially symmetrically about a transverse axis of symmetry. Furthermore, the number of return channels can be greater (e.g., eight) than the number of inlet channels (e.g., six), particularly in a heat exchanger located directly at the inlet and outlet of a heat exchanger arrangement.

[0028] This is for example in Fig. 4 where the heat exchanger of Fig. 3 is provided as the first, left heat exchanger 10.1. As in Fig. 4, the heat exchanger 10.1 is connected to a further heat exchanger 10.2, which is arranged according to the Fig. 1, so that the refrigerant flows first through the heat exchanger 10.1, then through the heat exchanger 10.2, and from there back through the heat exchanger 10.1 to the outlet 22. By the in Fig. 4, several distributed batteries can be cooled. Finally, several arrangements according to or similar Fig. 4, for example with a mirror-inverted heat exchanger according to 10.1, another heat exchanger parallel below or above 10.2, or the arrangement of Fig. 4 mirrored once more.

Claims

[1] Heat exchanger (10) with at least one plate (12) which can be attached to a battery module of an electric vehicle, wherein numerous at least partially parallel channels (14) for the evaporation of coolant are formed in a plane parallel to the plate (12) and are branched from at least one common inlet (16) and / or outlet (22), wherein at least one intermediate channel (20) which begins at a branch is branched again, and more than two intermediate channels (20) begin at at least one branch, characterized by , that at least one flow guide element (26) is provided in at least one branch and that at least one flow guide element (26) is formed over the entire clear height of an inlet channel (18). [2] Heat exchanger (10) according to claim 1, characterized by , that at least one flow guide element (26) in a plan view of the plate plane is round is trained. [3] Heat exchanger (10) according to one of the preceding claims, characterized by that all channels (14, 18, 20) have the same clear height. [4] Heat exchanger (10) according to one of the preceding claims, characterized by that in the case of two or more inlets (16) and / or outlets (22), channels (14) connected to the same inlet (16) or outlet (22) are at least partially symmetrical to other channels (14) connected to a different inlet (16) or outlet (22). [5] Heat exchanger (10) according to one of the preceding claims, characterized by that the plate can withstand a pressure of at least 20 bar, preferably at least 60 bar. [6] Heat exchanger (10) according to one of the preceding claims, characterized by that at least two parallel channels (14) are locally connected to each other. [7] Heat exchanger (10) according to one of the preceding claims, characterized bythat the inlet (16) and outlet (22) are arranged in such a way that adjacently arranged channels (14) are flowed through in countercurrent. [8] Heat exchanger arrangement with several heat exchangers (10) according to one of the preceding claims.

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