Plate heat exchanger

Abstract

Plate heat exchanger (1) with - a plate (2) for transferring heat energy to a heat transfer medium, in particular a cooling or refrigerant, - a flow channel bounded at least on one side by the plate (2) for channeling a flow of the heat transfer medium along the plate (2) in a predetermined flow direction (3) and - a multitude of knobs (4) projecting from the plate (2) into the flow channel for distributing the heat transfer medium within the flow channel, - wherein at least two adjacent knobs (4) are connected to each other and to a channel boundary (9) in such a way that they form a flow barrier (5, 6) running transversely to the flow direction (3) to block the flow direction (3), - where the plate (2) - a nozzle area (7) with a specified nozzle area width (E), - a cooling area (8) adjacent to the nozzle area (7) with a predetermined cooling area width and - comprising a main flow area arranged in the cooling area (8) in a straight line extension of the nozzle area (7) according to the flow direction (3), - wherein the knobs (4) in the cooling area (8) are arranged in a plurality of rows running transversely to the flow direction (3) such that each pair of successive rows in the flow direction (3) has a predetermined row spacing, - wherein the studs (4) in the cooling area (8) are arranged in a grid formed by the rows such that within a row two adjacent studs (4) have a predetermined stud spacing (B), - wherein a channel boundary (9) at least partially circumferentially surrounds the plate (2) and limits the flow channel, wherein the grid has an orthogonal boundary distance (A) to the channel boundary (9) along the flow direction (3) and a lateral boundary distance (C) to the channel boundary (9) transversely to the flow direction (3), characterized in that - that the nozzle area (7) is off-center and an internal stud (4) adjacent to the cooling area (8) in the off-center nozzle area (7) is connected to the channel boundary (9) over a length which is at least 5 percent and at most 50 percent of the nozzle area width (E), - that a first flow barrier (5) in the cooling area (8) extends over at least 5 percent and at most 60 percent of the cooling area width and projects into the main flow area by a distance (D) which is less than 75 percent of the nozzle area width (E).

Description

[0001] The invention relates to a plate heat exchanger according to the preamble of claim 1. The invention further relates to an electric motor vehicle with such a plate heat exchanger according to the preamble of claim 4.

[0002] An electric vehicle, electric car (E-car), or electric mobility vehicle (E-mobility vehicle) is, according to common understanding, a motor vehicle that is at least partially powered by an electric motor and can draw the electrical energy required for its propulsion from an internal energy storage system. A critical aspect of the development of electric vehicles is this energy storage system, since, unlike rail vehicles, electric vehicles cannot remain connected to a stationary power grid while driving. Only with high-performance energy storage systems with high energy density can electric vehicles achieve ranges comparable to those of combustion engine-powered vehicles. With current technology, ranges of up to 250 km and more are achievable in this way.

[0003] In this context, the term "electric vehicle" explicitly includes hybrid electric vehicles, also known as hybrid electric vehicles (HEVs), hybrid vehicles, or hybrid cars. This encompasses motor vehicles powered by at least one electric motor and another energy converter, and which can draw the energy required for their operation from a fuel tank in addition to the aforementioned electrical energy storage.

[0004] The high energy density and performance of the energy storage devices used in electric vehicles often result in considerable heating during operation, so electric vehicles of this type are typically equipped with suitable air or liquid cooling.

[0005] A plate heat exchanger according to the preamble of claim 1 is known from US 2006 / 0249281A1. Further plate heat exchangers are described in US 5810077A, JP 2011-232020A, DE 69422207T2, and US 6267177B1. Furthermore, a method for charging an electric vehicle connected to an electrical power supply is known from DE 102011079415A1.

[0006] DE 199 61 826 A1 proposes an evaporator for use in the automotive industry, which has first connection areas or points with an identical shape and a random or irregular orientation, wherein second connection areas with a larger cross-section than the first connection areas are provided adjacent to at least one fluid inlet. One plate of the evaporator includes openings at its ends for supplying refrigerant, as well as channels to allow the fluid to flow from one end of the plate to the other. The plots or connection areas, which are elongated and essentially identical in shape, are distributed in such a way that their orientations are random or arbitrary. The connection areas have a cross-section, which is exemplified as being between 5 mm. 2 and 15 mm 2 , particularly preferably of equal to 6 mm 2Adjacent to the openings, i.e., in a flow direction change area, are connection areas, e.g., in the case of two, with larger dimensions than the connection areas, for example, between 20 mm. 2 and 35 mm 2 , particularly preferably of equal to 21 mm 2 , arranged.

[0007] EP 1 308 687 A1 discloses the flow channel in a disk of a heat exchanger, through which a fluid flows and which is designed to facilitate heat exchange between an external environment and the fluid, which is formed by at least two plates connected to define a circulation line, the cross-section of which is a flow cross-section for the fluid, wherein the circulation line has an inlet opening for the fluid and an outlet opening for the fluid, and wherein the pipe has a means for the partial closure of the circulation line, which is designed to keep the flow cross-section of the line between the inlet opening and the outlet opening substantially constant.

[0008] Finally, DE 41 42 177 A1 proposes providing a plate heat exchanger with channels through which fluid flows in co-current or counter-current flow. These channels are formed, on the one hand, by individual plates connected to form pairs and, on the other hand, by the plate pairs assembled to form a plate stack. To distribute the media entering through the inlet cross-sections across the full channel width within a short axial inlet area, the individual plates are provided with guide vane-like projections that extend into the respective flow channel from at least one side. To improve heat exchange performance, the individual plates can be provided with profiles extending from the inlet area across the entire channel width and length, preferably consisting of a plurality of individual nubs, to generate turbulence in the channels.

[0009] A problematic aspect of such plate heat exchangers is the uniform distribution of the coolant within the plates. This can lead to the formation of poorly circulated areas, for example, in the corners of the plates, which significantly impairs the temperature homogeneity of the entire heat exchanger. Reducing the channel width is insufficient to solve this problem, as it can usually only be achieved at the cost of a pressure drop caused by the meandering shape of the channels. However, optimally designing the inlet and outlet areas of a plate heat exchanger with wide flow channels requires extensive fluid mechanics calculations, which, given their complexity, increase the development time and costs.

[0010] The invention is therefore based on the objective of providing a plate heat exchanger with a standardized studded field, which is characterized by a more uniform distribution of the coolant and a correspondingly homogeneous temperature distribution.

[0011] These problems are solved by a plate heat exchanger having the features of claim 1 and an electric motor vehicle having the features of claim 4.

[0012] The invention is therefore based on the fundamental idea of ​​selectively connecting individual protruding knobs within the flow channel of a plate heat exchanger to achieve a more uniform distribution of the heat transfer fluid. Specifically, two knobs located next to each other in the flow direction are combined to form a flow barrier oriented transversely to the flow direction. This barrier blocks the flow in that section of the flow channel and forces the heat transfer fluid to take a lateral detour. "Transverse" in this context does not exclusively mean perpendicular to the flow direction.

[0013] A particular advantage of this approach lies in its universal applicability for flow optimization with a wide variety of channel geometries. On the one hand, the invention can be used to improve plate heat exchangers of the type with a U-shaped flow channel, as discussed in the previously cited DE 199 61 826 A1 and EP 1 308 687 A1. On the other hand, plate heat exchangers such as that of DE 41 42 177 A1, which are based on an I- or Z-shaped flow channel with a central connection nozzle, can also be subjected to optimization of their stud geometry in accordance with the invention.

[0014] The homogenization of the flow achieved by means of one embodiment of the invention may, in these cases, begin not only in the main flow area of ​​the plate heat exchanger—which serves, for example, for cooling—but already in its upstream connection nozzle area. Thus, the off-center nozzle position, for example in U-type plate heat exchangers, can be adequately accommodated by connecting an inner nub of the nozzle area adjacent to the cooling area to a channel boundary surrounding the plate to block the flow direction. With a central nozzle position, as is characteristic, for example, of I-type devices, two central nubs of the nozzle area adjacent to the cooling area can serve as the starting and ending points of a corresponding flow barrier.

[0015] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0016] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0017] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0018] They show, each schematically Fig. 1 the partial top view of a plate heat exchanger with off-center nozzle according to a non-inventive embodiment, Fig. 2 a more detailed top view of a plate heat exchanger with an off-center nozzle according to an embodiment of the invention, Fig. 3 one of the Fig. 2 corresponding top view of a plate heat exchanger with central nozzle according to a non-inventive embodiment, Fig. 4 a more comprehensive top view of the plate heat exchanger with off-center nozzle according to the embodiment according to the invention Fig. 2, Fig. 5 one of the Fig. 4. Corresponding top view of the plate heat exchanger with central nozzle according to the non-inventive embodiment of the invention and Fig. 6 one the Fig. 4 and Fig. 5 corresponding top view of a plate heat exchanger with central nozzle according to a non-inventive embodiment of the invention.

[0019] The top view of the Fig. Figure 1 illustrates a plate heat exchanger 1 whose flow barriers are arranged outside the shown section. In this respect, it serves Fig. 1 merely explains the basic geometry of a plate heat exchanger 1 underlying the inventive approach, the flow path of which corresponds to the common U-type design. Comparable plate heat exchangers (PHEs) are also referred to in thermal engineering, depending on the application, as plate heat exchangers (PWTs) or plate coolers (PCs), but generally share the same operating principle.

[0020] How Fig. As can be seen in Figure 1, a plate 2 of the plate heat exchanger 1 comprises a plurality of regularly distributed studs 4, of which, for the sake of clarity, only one stud 4 is marked with a reference numeral. The studs 4 are distributed across a nozzle area 7 – serving for connecting the plate heat exchanger 1 to a corresponding cooling or refrigerant circuit – and an adjacent cooling area 8 of the plate 2, with a clear majority of the studs 4 being located in the latter area 8. The studs 4 of the illustrated embodiment, which are designed as convex protrusions of the plate 2, have – irrespective of the possibility of alternative, e.g., oval or teardrop-shaped configurations – the spatial geometric form of spherical caps of a height that is essentially perpendicular to the base plane of the plate 2 and thus to the coplanar plane of consideration of the plate 2. Fig. 1 is listed.

[0021] Due to their shape and orientation, the studs 4 project a considerable portion of their height into the flow channel of the plate heat exchanger 1 – formed by the plate 2 and laterally by a channel boundary 9 surrounding it – and, through their specific profile, cause turbulent flow, which is significantly enhanced by the matrix-like arrangement of the studs 4 shown. As well as a second, in Fig. As can be seen in the embodiment of a plate heat exchanger 1 shown in Figure 2, the studs 4 in the cooling zone are arranged in a plurality of rows – running transversely to the flow direction 3 of the heat transfer medium along the plate 2 – such that two successive rows of studs 4 are approximately equidistant. Within a row, the studs 4 are also distributed essentially equidistantly across the width of the flow channel at a predetermined stud spacing B. Schematically, the rows of the grid structure formed by the studs 4 alternate in pairs such that two rows arranged one behind the other in the flow direction 3 are offset from each other by half the aforementioned stud spacing B. In an alternative embodiment, in Fig. In the embodiment not shown, a different offset of the rows of studs may be chosen instead, without leaving the scope of the invention.

[0022] A basic dimension underlying the flow obstruction according to the invention is the width E of the element in the embodiment of the Fig. 2. Internal nozzle area. Within the nozzle area itself, a stud 4, located internally at its transition to the cooling area, is connected to the channel boundary 9 over a length that is between 5 percent and 50 percent of the nozzle area width E. Also within the cooling area, a first flow barrier 5 projects into the main flow of the nozzle area by a distance D, satisfying the mathematical equation 0 < D < 0.75 · E. The total length of the first flow barrier 5 is determined by the geometry of the cooling area and specifically corresponds to between 5 percent and 60 percent of its width. The flow barriers can also be positioned (additionally) in the second or third row of studs, perpendicular to the flow direction.

[0023] A second flow barrier 6 is located centrally in the resulting inner flow channel of the cooling area and at a predetermined lateral boundary distance C from the channel boundary 9, perpendicular to the flow direction 3. The grid formed by the knobs 4 also has an orthogonal boundary distance A along the flow direction 3, for which the relationship 0.5 · (B + C) < A < 2 · (B + C) applies. Corresponding flow barriers may also be arranged in a Fig. 2. The deflection area of ​​plate 2, not shown, is provided.

[0024] Fig. Figure 3 illustrates a third embodiment of the plate heat exchanger 1, which differs from that of the Fig. 2 differs from the other design variant by the central position of the nozzle area of ​​its plate 2, as is used, for example, in an I-shaped flow. In this design variant, the connection of an internal stud to the channel boundary 9 is replaced by that of the studs 4 arranged centrally at the transition between the nozzle and cooling area, so that the integrally designed stud 11 obstructs the flow direction 3 over a width of between 5 percent and 50 percent of the nozzle area width E.

[0025] As the Fig. 4 and Fig. As shown in Figure 5, based on a more comprehensive overview of the second and third embodiments of the plate heat exchanger 1, further flow barriers corresponding to the first flow barrier 5 and the second flow barrier 6 are also provided in an axially symmetric arrangement in an outflow area of ​​the respective plate 2.

[0026] Fig. Figure 6 finally clarifies that in an alternative, fourth embodiment of a plate heat exchanger 1, the nozzle area may also be completely free of nubs. Notwithstanding this, in the present embodiment, the cooling area covered with nubs 4 also comprises the first flow barrier 5, the second flow barrier 6, and their respective axially symmetrically arranged counterparts according to an analogous scheme.

[0027] As the Fig. 4, Fig. 5 and Fig.As indicated in Figure 6, the respective plate heat exchanger 1 can be advantageously used in the context of a generic electric vehicle 10 in order to dissipate the heat released during energy conversion by means of a cooling or refrigerant flowing through the plate heat exchanger 1 - which is preferably arranged in the immediate vicinity of the energy storage device for battery cooling - and thus prevent overheating of the electric vehicle 10.

Claims

[1] Plate heat exchanger (1) with - a plate (2) for transferring heat energy to a heat transfer medium, in particular a cooling or refrigerant, - a flow channel bounded at least on one side by the plate (2) for channeling a flow of the heat transfer medium along the plate (2) in a predetermined flow direction (3) and - a multitude of knobs (4) projecting from the plate (2) into the flow channel for distributing the heat transfer medium within the flow channel, - wherein at least two adjacent knobs (4) are connected to each other and to a channel boundary (9) in such a way that they form a flow barrier (5, 6) running transversely to the flow direction (3) to block the flow direction (3), - where the plate (2) - a nozzle area (7) with a specified nozzle area width (E), - a cooling area (8) adjacent to the nozzle area (7) with a predetermined cooling area width and - comprising a main flow area arranged in the cooling area (8) in a straight line extension of the nozzle area (7) according to the flow direction (3), - wherein the knobs (4) in the cooling area (8) are arranged in a plurality of rows running transversely to the flow direction (3) such that each pair of successive rows in the flow direction (3) has a predetermined row spacing, - wherein the studs (4) in the cooling area (8) are arranged in a grid formed by the rows such that within a row each two adjacent studs (4) have a predetermined stud spacing (B), -whereby a channel boundary (9) which at least partially surrounds the plate (2) limits the flow channel, wherein the grid has an orthogonal boundary distance (A) to the channel boundary (9) along the flow direction (3) and a lateral boundary distance (C) to the channel boundary (9) transversely to the flow direction (3), characterized by , - that the nozzle area (7) is off-center and an internal stud (4) adjacent to the cooling area (8) in the off-center nozzle area (7) is connected to the channel boundary (9) over a length which is at least 5 percent and at most 50 percent of the nozzle area width (E), - that a first flow barrier (5) in the cooling area (8) extends over at least 5 percent and at most 60 percent of the cooling area width and projects into the main flow area by a distance (D) which is less than 75 percent of the nozzle area width (E). [2] Plate heat exchanger (1) according to claim 1, characterized by , that the two consecutive rows are offset from each other by half the stud spacing (B). [3] Plate heat exchanger (1) according to claim 1 or 2, characterized by , that a second flow barrier (6) is arranged in the main flow area such that the orthogonal boundary distance (A) is at least 50 percent and at most 200 percent of the sum of the stud spacing (B) and the lateral boundary distance (C). [4] Electric motor vehicle (10) with - an electrical energy storage device for storing electrical energy, - an electric motor for converting electrical energy into kinetic energy, releasing heat and - a heat transfer medium, in particular a cooling or refrigerant, for removing the heat energy, characterized bya plate heat exchanger (1) adjacent to the energy storage unit and through which the heat transfer medium flows, according to one of claims 1 to 3 for cooling the energy storage unit.

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