CHILLER WITH TWO SUBSTANTIALLY PARALLEL PLATES

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

[0001]This is a U.S. national phase patent application of PCT/KR 2023/020271 filed Dec. 9, 2023, which claims the benefit of and priority to German Patent Application No. 10 2023 210 867.4, filed on Nov. 2, 2023, and German Patent Application No. 10 2023 200 472.0 filed Jan. 23, 2023, the entire contents of each of which are incorporated herein by reference for all purposes.

TECHNICAL FIELD

[0002]The invention relates to a chiller with two substantially parallel plates.

BACKGROUND ART

[0003]From DE 10 2021 210 826 A1, for example, a chiller having three substantially parallel plates is known, the outer two of which are essentially flat. The middle plate defines flow channels for coolant or refrigerant and is mechanically joined, usually soldered, to the first-mentioned plates.

[0004]JP H 11-287580 A describes a similar chiller around which air flows.

[0005]Finally, DE 11 2021 004 917 T5 relates to a heat exchanger between two liquids, wherein each liquid is divided into a plurality of flow channels or flow spaces within the heat exchanger.

SUMMARY

[0006]Against this background, the invention is based on the problem of creating a chiller that is compact and/or provides improved heat transfer.

[0007]The solution to this problem is shown and described herein.

[0008]This comprises two substantially parallel plates which are formed and connected to one another, in particular soldered, in such a way that at least one flow channel formed in the one plate is interrupted, and this plate has at least one barrier such that a fluid flow, in particular refrigerant flow, is deflected into a flow channel formed in the other plate.

[0009]In other words, the flow channels are formed in sections and alternate between one plate and the other. With regard to the flat areas between any flow channels, the plates are parallel with and joined to one another. To ensure the described deflection from a flow channel in one plate to a flow channel in the other plate, the flow channels formed in the respective plate overlap. The aforementioned barriers, which essentially form the end of a flow channel section formed in a plate, thus act as guiding elements for deflection and as turbulators to improve heat transfer. At the same time, the chiller or in general the heat exchanger can be kept compact. As described in more detail below, the plates can also be joined together in such a way that they withstand particularly high stresses due to internal pressure.

[0010]If a space between two plates is usually defined as a plane, a conventional fluid flow, in particular a refrigerant flow, can be described as two-dimensional. In contrast, the flow formed in the heat exchanger according to the invention is three-dimensional in that the fluid, in particular refrigerant, flows at least in sections in a depression, channel or elevation of a first plate, bounded by an adjacent flat area of the second plate, and in another section in an elevation, depression or channel of the second plate, bounded by an adjacent flat area of the first plate.

[0011]Put another way, if a layout of the one or more flow channels is marked with different colors denoting a flow in a depression or similar of the one plate on the one hand, and of the other plate on the other hand, this will appear as different colors in the course of the flow channel. A second fluid, for example a coolant, which gives off heat to the refrigerant flowing alternately in the plates, flows in the remaining plate gaps, which are bounded by a circumferential lateral web. In this case, both a direct current and a counter-current, as well as a cross-counter-current, can be formed in the heat exchanger.

[0012]Furthermore, the chiller typically has substantially flat outer plates on the outer sides, which preferably have inlets and outlets for a fluid that gives off heat to a refrigerant, for example. This essentially provides a means of connection to the fluid system of a vehicle. In principle, a connection can be disposed on both sides of the chiller and on each of the two outer plates.

[0013]For the sake of completeness, it should be mentioned that the at least four plates, including the outer plates, are mechanically connected to each other in a suitable manner, in particular soldered, so as to create a chiller with high strength overall. This concerns resistance both to internal pressure and to external mechanical stress.

[0014]The chiller can also be connected to the cooling system of a vehicle. Furthermore, the chiller according to the invention has low pressure loss and, as mentioned, high strength. Depending on the requirements, the outer and/or any intermediate or separating plates can be fully in line with the plates in which flow channels are formed, or offset inwards on at least one side.

[0015]In the area of overlap between two cooling channel sections in two different plates, this results in a flow channel height that is twice as great as the depth of the depression formed in one plate. The same applies to the flow space for fluid in the remaining plate gaps, with the exception of the flow spaces for fluid adjacent to the outer plates.

[0016]It should also be mentioned that, for the refrigerant inlets and outlets, i.e. in the plate gaps described, for a plate thickness of 0.6 mm, for example, a diameter of 4.0 to 4.4 mm is preferred, and for a plate thickness of 0.4 mm a diameter of 2.8 to 3.2 mm is preferred.

[0017]The chiller according to the invention is particularly pressure-stable due to the fact that a separate inlet and preferably also a separate outlet is assigned to at least two flow channels, preferably to each flow channel in the respective plate, in other words, the fluid flow, in particular refrigerant flow, is already divided into a plurality of channels outside the plates where stability can be ensured more easily.

[0018]Advantageously, therefore, heat is efficiently transferred to a second, liquid fluid by forming a closed flow space for a second fluid, for example a coolant, between the plates.

[0019]Currently preferred areas of application for the chiller according to the invention are coolant chillers and direct refrigerant evaporators.

[0020]Preferred further developments are described herein.

[0021]The design according to the invention can advantageously be realized by a single type of plate with flow channels, which is alternately rotated through 180° and installed in the heat exchanger. This means that only a single type of flow pattern, for example U-shaped or meandering, or multiple U-shaped patterns, can be realized inside the heat exchanger. Together with the outer plates as a further plate type, two types of plate are therefore sufficient. Since it could offer advantages in certain applications to provide a second type of flow pattern in such a heat exchanger, this too can be efficiently realized in an advantageous manner by using a maximum of two different types of plate with flow channels.

[0022]As previously mentioned, the flow channels according to the invention can be realized by interconnecting one and the same type of plate, one of which is rotated through 180°, for example.

[0023]At the same time, the thickness of at least one plate can be advantageously reduced to 0.6 mm or less without unduly reducing the strength. The plate thicknesses may differ depending on the manufacturing process and the respective requirements. A minimum thickness of 0.4 mm is currently preferred, and initial simulations and tests have shown depths of 0.65 to 0.8 mm to be advantageous for a flow channel formed in a plate. This results in a total height or depth of 1.3 to 1.6 mm in the area of overlaps of two flow channel sections where two plates lie one on top of the other. Such dimensions are currently regarded as the optimum in terms of a robust soldering process, pressure loss, heat transfer performance, and strength.

[0024]With regard to the flow geometry, initial simulations have shown that a meandering flow and/or where appropriate a multiple, in particular triple U-shape and/or a rectilinear flow are advantageous. The meanders can be comparatively complex and thus specially adapted to the requirements. A U-shape essentially has sections connected at right angles.

[0025]With regard to the mechanical internal pressure resistance of the chiller, it is currently preferred that it should withstand an internal pressure corresponding to the maximum operating pressure of refrigerant R744 in order to form a particularly stable chiller. Such a value can be achieved in particular by minimizing free spanned areas between the plates by connecting the plates to each other at numerous points and/or in parallel with numerous flow channels. Internal pressure resistance can then be ensured despite plate thicknesses of 0.6 mm or less.

[0026]Heat transfer can also be improved in an advantageous way by turbulators which are preferably disposed outside the flow channels, in other words, in the coolant flow space. The turbulators may be formed by notches, which may be round or oval, and a plurality of such turbulators may be provided in series substantially parallel to the flow channels. The turbulators are preferably provided in one piece in the plates, in the form of said notches or punchings and/or bends. The maximum height of such turbulators can correspond to the height of the flow space, so that, in other words, they adjoin the upper boundary of a flow space.

[0027]In the interest of efficient heat transfer, it is also preferred that the second fluid is guided through a plate gap in a V-shape and/or in an arc. As already indicated above, it may be advantageous to provide a different flow in different areas of a heat exchanger so that in a first group of plates the flow channels are formed in a first shape, for example rectilinearly, and in a second group of plates the flow channels are formed in a second shape, for example a U-shape.

[0028]In particular, this can improve performance and at the same time make it possible to form any connections or as many connections as possible on a single side of the heat exchanger.

[0029]Finally, for the stable connection of the plate it has proven advantageous to join them together, in particular to solder them, in the area of inlets and outlets and/or on the outer edge. Furthermore, alternatively or additionally, at least one stiffening plate and/or, on at least one outer edge, at least in sections or in places, a fold can be provided. A stiffening plate can be provided in particular in the area of the refrigerant inlet and outlet, and/or a tie rod can be configured such that it is inserted through additional holes formed with a collar and soldered to each plate. This distributes tensile force from the top plate to a plurality of plates, down to all plates including the bottom plate. Such a tie rod can be round, oval or rectangular or have any other shape. Furthermore, a plurality of such tie rods can be provided. Alternatively or additionally, the plate stack forming the heat exchanger can be enclosed by a strip, for example of aluminum, which can be soldered to the plate stack, particularly in an area subject to the greatest mechanical stress. Finally, one or more C-shaped brackets can be provided on the outside of the plate stack to hold the plate stack together. At least one such bracket can contain one or more connections; in any case, at least one such bracket is preferably provided in the area of the connections because these areas are critical with regard to the pressure stresses that occur.

[0030]With a view to favorable properties, it is further preferred that all inlets and outlets for the first fluid have a diameter of 4.0 to 4.4 mm, in particular with a plate thickness of approximately 0.6 mm, or a diameter of 2.8 to 3.2 mm, in particular with a plate thickness of approximately 0.4 mm.

[0031]It is also advantageous for the stability of the plate stack if all inlets and outlets for the first fluid are surrounded by an elevation or depression formed from the plate material.

[0032]This applies equally to the preferred measure whereby the elevation or depression adjoins an elevation or depression that forms a flow channel. All elevations and depressions can be configured efficiently, and the said structures favor the flow to and within the channels.

[0033]The manufacture and connection of the plates is particularly easy if all the elevations or depressions are the same height or depth.

[0034]This also applies to the preferred measure whereby sections of flow channels formed in different plates are at least partially of the same length. This also improves the flow pattern.

[0035]Particularly good properties are also expected if, in each plate, a flow channel adjoins each inlet and outlet, so that, in other words, the fluid flow is not deflected immediately after entering a neighboring plate.

DESCRIPTION OF DRAWINGS

[0036]The invention is explained in more detail below with reference to exemplary embodiments. The following are shown:

[0037]FIG. 1: The basic structure of the chiller according to the invention.

[0038]FIG. 2: Plan view of a first type of plate in the chiller shown in FIG. 1.

[0039]FIG. 3: Plan view of a second type of plate in the chiller shown in FIG. 1.

[0040]FIG. 4: Part of a further embodiment of a chiller according to the invention.

[0041]FIG. 5: Part of a further embodiment of a chiller according to the invention.

[0042]FIG. 6: Part of a further embodiment of a chiller according to the invention.

[0043]FIG. 7: Part of a further embodiment of a chiller according to the invention.

[0044]FIGS. 8-12: The plates used in the embodiments of FIGS. 4-7.

[0045]FIG. 13: Detail of the chiller according to the invention.

[0046]FIG. 14: A further embodiment of a plate used in the chiller.

[0047]FIG. 15: The plate shown in FIG. 14 rotated through 180°.

[0048]FIGS. 16-18: Sections through two plate pairs containing volumes as per FIGS. 14 and 15, with FIG. 16 showing a cross-section perpendicular to a flow channel, and FIGS. 17 and 18 showing cross-sections parallel to a flow channel.

[0049]FIG. 19: Section through two plate pairs together with outer plates.

[0050]FIGS. 20-22: The flow in the first, the second and in both plates combined.

[0051]FIG. 23: A further embodiment of a plate.

[0052]FIG. 24: A first section through a plate stack with a plurality of the plates shown in FIG. 23.

[0053]FIG. 25: A second section through the plate stack with a plurality of the plates shown in FIG. 23.

DESCRIPTION OF AN EMBODIMENT

[0054]As can be seen from FIG. 1, the chiller 10 according to the invention comprises numerous plates, which are described in more detail below. All plates are typically essentially rectangular, and the outer plates 14 are essentially flat, at least on their outer sides. The intermediate plates 12 have structures described in more detail below to form flow channels. In the case shown, the top outer plate in the figure also has inlets and outlets 16-22, which are also described in more detail below and can be adapted to customer requirements.

[0055]Specifically, in the case shown, the top outer plate 14 has an inlet 16 and an outlet 18, for example for coolant which is to be cooled by the chiller 10 according to the invention. As indicated by the arrows A and B, in the orientation shown, the coolant flows essentially from top to bottom through all the plate gaps described in more detail below, and upwards from the bottom of the chiller 10 to the outlet 18. Specifically, the coolant is distributed through the passages 36 formed in all plates to all the plate gaps where it flows in a U-shape, essentially from front left to rear right, from there to the front right and finally to the front left, in order to pass through the passages 36, which again can be seen, to the outlet 18. FIGS. 2 and 3 show interrupted flow channels 34 for the refrigerant, which are described in more detail below. The coolant essentially flows between them, in particular in a U-shape as a result of the central boundary 58. The inlet 16 and outlet 18 are essentially cylindrical with a tapered section approximately in the middle and can be soldered to the outer plate 14.

[0056]The same applies to the block 24 to be seen, which has an inlet 20 and an outlet 22 for a refrigerant. The block 24 can be formed by milling, for example, in view of the higher pressure load in this area.

[0057]Numerous openings 26 can be seen in the right-hand area of the outer plate 14, through which the refrigerant enters numerous flow channels, which are described in more detail below. On the basis of FIG. 1, it is explained that the refrigerant initially flows to the front left following the arrows C in the left-hand area of the plate stack 28 which can be seen. As can be seen from the vertical arrow C, this takes place in parallel throughout the entire plate stack 28. For the sake of clarity, only the two lowest plates of this plate stack 28 are shown separated from one another. The part of the plate stack 28 that can be seen above them consists of identical plates which are, however, shown stacked.

[0058]The same applies to the lower plate stack 30, which is separated from the upper plate stack 28 by a separating or intermediate plate 32. For the upper plate stack 28, a rectilinear flow was described following the arrows C pointing from rear right to front left. In contrast, a U-shaped flow is formed in the lower plate stack 30 such that the refrigerant flows in parallel in all flow channels of this plate stack 30, first from front left to rear right following arrows D, then from rear left to rear right following arrows E, and then from rear right to front left following arrows F. From here the refrigerant flows upwards, now into the right-hand part of the upper plate stack 28 and here, again flowing in parallel in all flow channels following the arrows G, from front left to rear right, thus rectilinearly, and from there following the arrow H to its outlet 22.

[0059]Since the coolant entering through the inlet 16 flows in the upper plate stack in its left-hand area from front left to rear right, it runs in counterflow to the refrigerant. A parallel, U-shaped flow is created in the lower plate stack. A counterflow is also formed in the right-hand part of the upper plate stack 28. This extends the flow paths in an advantageous way and improves heat transfer. This applies in particular to the counterflow in the right-hand area of the upper plate stack 28, which is especially advantageous for cooling the coolant that subsequently leaves the chiller 10. At the same time, in the case of the chiller 10 shown in FIG. 1, all inlets and outlets 16, 18, 20 and 22 can advantageously be disposed on one side, which offers advantages for connecting the chiller to the cooling system of a vehicle, for example.

[0060]As shown in FIG. 2, the plates 12 of the upper plate stack 28 have, on the one hand, openings 26 for refrigerant and, on the other hand, interrupted flow channels 34 and passages 36, described in more detail below, for example four to six parallel flow channels 34 and passages 36 for refrigerant on the one hand and coolant on the other. The plate shown in FIG. 2 is configured for a rectilinear flow, at the top from right to left and at the bottom from left to right in the case shown, with regard to the refrigerant. Furthermore, in the example given, turbulators 38 are shown in the upper area between the flow channels, which are described in more detail below. As can be seen in FIG. 2, in this case they are elongated in the refrigerant's flow direction and in series with the flow channels 34 for the refrigerant.

[0061]The same applies to the plate 40 of the lower plate stack 30 shown in FIG. 3. As can be seen in the right-hand area in particular, the refrigerant is deflected in its flow channels 34, resulting in an overall U-shaped flow.

[0062]In the alternative embodiment shown in FIG. 4, the flow is essentially triple U-shaped, as explained in more detail below. Here, the middle U is upside down and its two legs coincide with the inner legs of the outer U. In this case the refrigerant inlet 20 and outlet 22 are separated, and the refrigerant first flows into the individual flow channels following arrow C, then, as described, in a triple U-or meandering pattern following arrow D to the right and from there to the outlet 22. The coolant inlet and outlet can again be seen as essentially cylindrical and can be used both in parallel with and in counterflow to the refrigerant.

[0063]FIG. 5 essentially shows a duplication of the flow shown in FIG. 4, whereby the flow in the two upper plates is essentially from left to right, and in the two lower plates from right to left, after the flow from the second plate has been guided into the third plate from above. The return flow to the outlet 22 after a further plate pair, for example as shown in FIG. 4 below, is indicated by the arrow H.

[0064]FIG. 6 shows how a refrigerant inlet 20 and outlet 22 can be advantageously disposed on one side of the chiller, namely by using a lower group 42 (cf. FIG. 8) of openings in a top plate for the inlet, with the refrigerant flowing from left to right in the upper plate pair shown in FIG. 7, from right to left in the middle plate pair and again from left to right in the bottom plate pair shown in FIG. 7. The overall resulting return flow after flowing through the plate pair shown in FIG. 6 below to the outlet 22 is indicated by the arrow H. For the concepts shown in FIGS. 4-7, it is emphasized that they advantageously allow all inlets and outlets 16-22 to be disposed on one side. This makes it easier to integrate the chiller into the cooling system of a vehicle, for example, without the need for external deflection of the refrigerant, for example. A combination of FIGS. 4 and 5 allows an odd number of deflections, and a combination of FIGS. 6 and 7 allows an even number of deflections.

[0065]As can be seen in more detail in FIG. 8, the top plate in each plate pair according to FIG. 7 corresponds to the first plate type shown in FIG. 8. The second plate type shown in FIG. 9 forms the bottom plate of the top and bottom plate pair, and the plate type shown in FIG. 10 forms the bottom plate of the middle plate pair. Arrows I in FIGS. 8 to 12, 14 and 15 show the essentially inverted V-shaped flow of the second fluid in the flow space between two plates from one passage 36 to the other in the orientation shown. The flow space extends on all sides as far as the outer boundary 60. The second fluid, typically a coolant, in particular water, is cooled and gives off heat to the refrigerant, which in this case flows in counterflow and essentially in a triple U-shape from top left to top right according to the figure, so that it evaporates. Heat is ideally transferred evenly along the respective flow path.

[0066]The remaining plate types shown in FIGS. 11 and 12 correspond to the plates shown in the lower part of FIGS. 4 and 6, with the plate type shown in FIG. 12 forming the upper plate.

[0067]Moreover, the two upper plate pairs in FIG. 7 correspond to the plate pairs shown in FIG. 5, and in the lower part of FIG. 4 the plate type in FIG. 11 is the upper plate and the plate type in FIG. 12 is the lower plate. As can be seen in FIGS. 8-12, different openings 26 are closed off in different plate types in order to realize the flow paths described above using the plates shown. Groups of openings, such as the group 42 indicated in FIG. 8, form collector areas that can be used advantageously for heat transfer. For all plate types, it can be seen that their respective flow channels for the refrigerant are interrupted, and the way in which the resulting chiller works is described in more detail below. The coolant flows from one passage 36 to the other in an essentially inverted V-shape or arc due to the respective central boundary 58.

[0068]FIG. 13 shows first how the block 24 with the refrigerant inlet 20 and/or outlet 22 is connected to the outer plate 14, how the latter is connected to an intermediate plate 12, and how a plurality of intermediate plates 12 are connected to one another. This is advantageously achieved by soldering, and it is emphasized that the resulting circumferential and double soldering of the plates in the indicated areas 44 ensures particular strength. As indicated by the folded edges 46, the strength can optionally be further increased by lateral folds. The double circumferential soldering in the indicated areas 44 provides additional protection against corrosion, as it is applied outside, according to FIG. 13 to the left of the soldering sufficient for the functioning of the chiller in the area of the mutually aligned bulges of the plates 12. Corrosion in the areas 44 cannot lead to any leakage of refrigerant or fluid, since the aforementioned soldering necessary for the functioning of the chiller is applied further towards the inside than these areas 44.

[0069]The same applies to the measure indicated in FIG. 14, whereby local dimples 48, which can be soldered together continuously for all plates, can be provided in one or more corners of the plates 12.

[0070]FIG. 15 illustrates the plate shown in FIG. 14 rotated through 180° about a vertical axis parallel to the plane of the plate according to the figure, which consequently also has interrupted flow channels. However, if the plate shown in FIG. 14 is soldered in this orientation to the plate shown in FIG. 15, likewise in the shown orientation, the overall result is continuous flow channels that are only formed in one of the two plates in some areas. Here, the refrigerant can flow from one plate into the other in the area where the flow channels of both plates overlap. The ends of the flow channel sections form barriers for deflection into the other plate.

[0071]FIG. 16 shows, by way of example based on the cross-section, that the refrigerant initially flows only in the upper plate 50 after entering the second opening 26 from the left. In the further course, however, the flow channel 34 formed therein ends, and the refrigerant enters a flow channel 34 formed in the lower plate 54 in the form of a depression in the area of the overlap. In the case shown, each flow channel 34 is assigned an opening 26 which is formed in further plates 50, 54 and in this respect acts as a distributor on the flow channels 34 of multiple plate pairs 50, 54.

[0072]This overlap is shown in FIG. 16 by way of example for the second flow channel 34 from the right and the flow channel 34 furthest to the left. In this area, the refrigerant thus flows in the channels of both plates 50, 54. For the flow channel 34 disposed furthest to the right, it can be seen that in this area the refrigerant flows only in a channel 34 formed in the lower plate 54, while the limited flow channel 34 formed in the upper plate 50 can be seen above it.

[0073]As can also be seen in FIG. 17, in the case shown the refrigerant alternates, starting from a flow only in the upper plate 50 in the area of the overlap 52, passing into the flow channel of the lower plate 54, and from there in the area of a further overlap 52 back into the flow channel in the upper plate 50.

[0074]This can also be seen in FIG. 18 which is labeled with identical reference numbers. The flow of coolant to be cooled, which can be seen in the remaining plate gaps 56, is also indicated here.

[0075]FIG. 19 also shows an example of how an arrangement of two plate pairs, each with an upper plate 50 and a lower plate 54, can be closed off by the essentially flat outer plates 14, with further flow spaces 56 for coolant adjacent to the outer plates 14. In the cross-section shown, the flow channel 34 located furthest to the left is located only in the respective upper plate 50, the second flow channel 34 from the left only in the lower plate 54, and the third from the left in both plates 50, 54.

[0076]FIG. 20 shows the interrupted areas in which refrigerant flows in this upper plate 50, corresponding to the flow channels of the upper plate 50 shown in FIG. 14.

[0077]FIG. 21 shows the same for the flow in the lower plate 54 corresponding to the flow channels seen in FIG. 15, and FIG. 22 shows the resulting overall flow alternating between the two plates via the different hatching of the flow channel in different plates.

[0078]FIG. 23 shows, by way of example, for a plate with the described triple U-shaped flow, how turbulators 38 can also be formed in series and parallel with the flow channels 34.

[0079]Finally, as can be seen in FIGS. 24 and 25, showing cross-sections perpendicular to each other, the turbulators 38 can extend over the entire height of the flow gap and consequently adjoin the respective upper plate or an outer plate 14. As the right-hand area of FIG. 25 also shows, the turbulators 38 can extend in both directions and can be punched out of the plate material in such a way that, with two connected plates, a single plate thickness results in the area of the turbulators 38, while in other areas, and in particular between flow channels 34, a double plate thickness is present.

[0080]The invention relates to a chiller with two substantially parallel plates.