Heat exchanger and method for manufacturing the heat exchanger

Abstract

Heat exchanger (10) with at least two heat exchanger layers (12, 14, 16), each of which has several tubes (20) arranged side by side, wherein the heat exchanger layers (12, 14, 16) are stacked on top of each other and are firmly connected to one another, wherein at least one positioning element (30, 32) is arranged between the heat exchanger layers (12, 14, 16), which has a receiving recess (301, 302, 321, 322) for each tube (20) for positioning the tubes (20) of the heat exchanger layers (12, 14, 16) relative to each other and is fluid-tightly connected to the heat exchanger layers (12, 14, 16), characterized in that the tubes (20) of a heat exchanger layer (12, 14, 16) are connected by a thread (22) to form a heat exchanger mat, wherein the positioning element (30, 32, 34, 36) and the thread (22) connecting the tubes (20) overlap in the longitudinal direction of the tubes (20).

Description

[0001] The invention relates to a heat exchanger, in particular a microchannel bundle heat exchanger. The invention also relates to a method for manufacturing a heat exchanger.

[0002] Such heat exchangers, in particular microchannel bundle heat exchangers, are generally known from the prior art and are used, for example, in motor vehicles for cooling charge air in a turbocharged internal combustion engine. These heat exchangers typically have several stacked heat exchanger layers or mats, each heat exchanger layer comprising a plurality of adjacent tubes, particularly plastic tubes. The individual heat exchanger layers are usually bonded together in such a way that a flow channel exists between them.During operation, a first fluid flows through the tubes of the heat exchanger layers, while a second fluid flows through the flow channel formed between the heat exchanger layers. The first fluid flows through the tubes in a first flow direction, and the second fluid flows through the flow channel in a second flow direction, perpendicular to the first flow direction. Such a heat exchanger is disclosed, for example, in DE 10 2020 105 454 A1.

[0003] From DE 10 2019 133 563 A1, a heat exchanger is known which has several heat exchanger layers, each of which has several tubes arranged side by side. The heat exchanger layers are stacked on top of each other and firmly connected to one another, such that at least one positioning element is arranged between the heat exchanger layers, which has a receiving recess for each tube for positioning the tubes of the heat exchanger layers relative to each other and is fluid-tightly connected to the heat exchanger layers.

[0004] From US 2008 / 0 135 219 A1, a heat exchanger with several hollow tubes is known, wherein the hollow tubes are braided, twisted or interlaced into a cord using commercially available winding and braiding equipment.

[0005] From DE 698 22 648 T2 a heat exchanger for a medical application is known which has several hollow tubes, wherein the hollow tubes are positioned relative to each other and connected to each other via a thread.

[0006] A problem with this type of heat exchanger design is that the heat exchanger layers are typically positioned and bonded manually by a worker, resulting in relatively high manufacturing costs and relatively low reproducibility. Furthermore, the spacing between the heat exchanger layers, and therefore the flow cross-section of the flow channel between them, varies depending on the mounting of the heat exchanger layers and thus their relative positions.

[0007] The object of the invention is to provide a heat exchanger and a method for manufacturing a heat exchanger in which the reproducibility in the manufacture of the heat exchangers can be increased and the manufacturing effort reduced.

[0008] The heat exchanger comprises at least two heat exchanger layers, each having several tubes arranged side by side, the heat exchanger layers being stacked relative to each other and rigidly connected. Preferably, the heat exchanger is arranged in a housing.

[0009] The tubes are preferably made of a plastic, in particular polyetheretherketone (PEEK), polyetherketoneketone (PEKK), or polyimide. The polyimide can be, for example, polysuccinimide (PSI), polybismaleimide (PBMI), polyoxadiazobenzimidazole (PBO), polyimidesulfone (PISO), polymethacrylimide (PMI), or another plastic with an imide group. During manufacturing, the tubes are extruded, for example. Extrusion is particularly recommended when the tubes are made of PEEK or PEKK. Alternatively, the tubes can also be dip-formed. This manufacturing process is particularly recommended when the tubes are made of polyimide. Alternatively, the tubes can also be made of another suitable material. For example, the tubes can be made of a metallic material, in particular stainless steel, titanium, or aluminum, which exhibit particularly high stability.

[0010] At least one positioning element is arranged between the heat exchanger layers. This positioning element has a receiving recess for each tube, used to position the tubes of the heat exchanger layers relative to one another, and is fluid-tightly connected to the heat exchanger layers. Preferably, two positioning elements are arranged between two adjacent heat exchanger layers, with the two positioning elements fluid-tightly defining a flow channel oriented transversely to the longitudinal axis of the tubes. During operation of the heat exchanger, the tubes are filled with a first fluid, and the flow channel with a second fluid.

[0011] The tubes of a heat exchanger layer are connected by a thread to form a heat exchanger mat. The thread can be, for example, a wire, a glass fiber, or a soluble or meltable polymer fiber. The thread allows the heat exchanger layers to be joined together to form a fabric. The positioning element and the thread connecting the tubes overlap in the longitudinal direction of the tubes. This creates a fluid-tight connection between the positioning element and the heat exchanger layers in the area of ​​the thread. Preferably, the groove-like adhesive channel and the thread connecting the tubes overlap in such a way that the thread partially engages in the groove-like adhesive channel, thereby pre-positioning the positioning element in the longitudinal direction of the tubes.

[0012] The positioning element is preferably made of a plastic and forms a template for manufacturing the heat exchanger. Each receiving recess has a semicircular cross-section, with the radius of the receiving recesses essentially corresponding to the radius of the tubes. The receiving recesses are arranged side by side such that a web with a predefined width is positioned between each adjacent receiving recess. The receiving recesses are located on both opposite sides of the positioning element. A web with a predefined width is provided between the receiving recesses formed on the opposite sides of the positioning element, thereby defining the distance between the heat exchanger layers and thus the flow cross-section of the flow channel.

[0013] During the manufacturing of the heat exchanger, the tubes of one of the heat exchanger layers are first inserted into the receiving recesses on one side of the positioning element and fluid-tightly connected to the positioning element. Subsequently, the tubes of the other heat exchanger layer are inserted into the receiving recesses on the other side and fluid-tightly connected to the positioning element. Alternatively, all tubes are first inserted into the receiving recesses and then fluid-tightly connected to the positioning element. In particular, two positioning elements, spaced apart longitudinally along the tubes, are positioned between the heat exchanger layers and fluid-tightly connected to the heat exchanger layers.

[0014] The fluid-tight connection between the positioning element and the tubes of the heat exchanger layers is achieved through a material-bonded connection, in particular by adhesive bonding. The adhesive can be applied to the positioning element before the tubes are inserted into the receiving recesses, or it can be applied after the tubes have been inserted. Alternatively, the positioning element itself can serve to create the material-bonded connection.

[0015] This allows for a simple and cost-effective way to create a fluid-tight connection between the positioning element and the heat exchanger layers. The adhesive bonds form such a fluid-tight connection between the positioning element and the heat exchanger layers that the flow channel between the tubes can be reliably established.

[0016] The at least one positioning element allows the heat exchanger elements to be positioned relative to each other in a predefined manner and then firmly connected. This gives the flow channel between the heat exchanger layers a predefined flow cross-section. In this way, the reproducibility of heat exchanger manufacturing can be increased, as the heat exchanger layers and the positioning element simply need to be sandwiched together, and the positioning of the components relative to each other is achieved through the positive fit between the positioning element and the tubes of the heat exchanger layers. Furthermore, the manufacturing process is simplified by eliminating the need for manual positioning of the heat exchanger layers relative to each other.

[0017] Preferably, an end-side positioning element is arranged on at least one of the heat exchanger layers on a side facing away from the positioning element, wherein the end-side positioning element has the receiving recess only on one side. The end-side positioning element thus forms the end of the heat exchanger. Preferably, an end-side positioning element is arranged at each end of the heat exchanger. Preferably, the heat exchanger is supported against a housing via the end-side positioning element.

[0018] Preferably, the positioning element has at least one adhesive channel extending along the adjacent tubes and featuring an adhesive injection opening. The heat exchanger layers are first inserted into the receiving recesses, and then the adhesive is injected through the injection opening into the adhesive channel. The adhesive channel extends transversely to the longitudinal axis of the tubes, from one end of the heat exchanger layers to the opposite end, ensuring that each tube is bonded to the positioning element. This allows the heat exchanger layers and the positioning element to be pre-assembled and then permanently fixed together.

[0019] Preferably, the positioning element arranged between two heat exchanger layers has a groove-like adhesive channel on each of its two sides facing one of the heat exchanger layers, enabling reliable bonding of both heat exchanger layers to the positioning element. In a preferred embodiment, the adhesive inlet opening is connected to one of the adhesive channels, with an opening for connecting the two adhesive channels provided in an intermediate wall. This allows both adhesive channels to be filled with adhesive via a common inlet opening, thus simplifying the manufacturing of the heat exchanger.

[0020] Preferably, the adhesive inlet opening is arranged at one end of the positioning element, thereby improving accessibility to the adhesive inlet opening and simplifying the manufacture of the heat exchanger.

[0021] In an alternative embodiment, the positioning element is at least partially made of a material that melts upon exposure to heat, in particular a thermoplastic material, and is designed such that, upon solidification of the material, the heat exchanger layers are bonded to the positioning element. Here, the tubes of the heat exchanger layers are inserted into the receiving recesses, and then at least the positioning element is heated, causing it to melt. The subsequent solidification of the positioning element creates a bond between the positioning element and the tubes of the heat exchanger layers. This simplifies the manufacturing of the heat exchanger by eliminating the need for a separate adhesive.

[0022] The problem is also solved by a method for manufacturing a heat exchanger according to any one of claims 1 to 9. For the individual steps of the method and its advantages, reference is made to the preceding paragraphs.

[0023] An embodiment of the invention is explained in more detail with reference to the drawings. Fig. Figure 1 schematically shows a heat exchanger in a top view. Fig. Figure 2 schematically shows the heat exchanger made of Fig. 1 in a cross-section, and Fig. Figure 3 shows a positioning element of the heat exchanger. Fig. 1 and Fig. 2 in perspective view.

[0024] The Fig. 1 and Fig. Figure 2 shows a heat exchanger 10, in particular a microchannel bundle heat exchanger. Such a heat exchanger 10 can be used in a wide variety of applications in a motor vehicle and is designed as a cross-flow heat exchanger.

[0025] The heat exchanger 10 comprises several heat exchanger layers 12, 14, 16 with a plurality of tubes 20, whereby only four tubes 20 per heat exchanger layer 12, 14, 16 are shown here as an example. In particular, in a microchannel bundle heat exchanger, the number of tubes 20 per heat exchanger layer 12, 14, 16 and the number of heat exchanger layers 12, 14, 16 are significantly higher than four.

[0026] The tubes 20 of the respective heat exchanger layers 12, 14, 16 are arranged side by side and each connected by a thread 22, in Fig. The two heat exchanger layers, shown in dashed lines, are connected at two points spaced apart from each other in the longitudinal direction of the tubes 20 to form a heat exchanger layer. At each of these points, a positioning element 30, 32 is arranged between two adjacent heat exchanger layers 12, 14, 16. An end-side positioning element 34, 36 is also arranged on each of the outer heat exchanger layers 12, 16, located on the side of the heat exchanger layers 12, 16 opposite the positioning element 30, 32.

[0027] The positioning elements 30, 32 arranged between two adjacent heat exchanger layers 12, 14, 16 have, as shown in Fig. Figure 2 shows several receiving recesses 301, 302, 321, 322 with a semicircular cross-section on both opposite sides, in each of which a tube 20 is positioned, wherein the tubes 20 of the heat exchanger layer 12 are arranged in the receiving bores 301, the tubes 20 of the heat exchanger layer 14 are arranged in the receiving recesses 302, the tubes 20 of the heat exchanger layer 14 are arranged in the receiving recesses 321 and the tubes 20 of the heat exchanger layer 16 are arranged in the receiving recesses 322. The end-side positioning elements 34, 36 also have several receiving recesses 341, 361 with a semicircular cross-section, wherein the tubes 20 of the heat exchanger layer 16 are arranged in the receiving recesses 341 and the tubes 20 of the heat exchanger layer 12 are arranged in the receiving recesses 361. The positioning elements 30, 32 each have an intermediate wall 305, 325 and the positioning elements 34, 36 each have an outer wall 343, 363.

[0028] The positioning elements 30, 32, 34, 36 are bonded to one or two heat exchanger layers 12, 14, 16, respectively. For this purpose, each positioning element 30, 32, 34, 36 has at least one adhesive channel 303, 304, 323, 324, 342, 362. The end-mounted positioning elements 34, 36 each have a single adhesive channel 342, 362, which extends transversely to the longitudinal direction of the tubes 20 and over all tubes 20. The positioning elements 30, 32 arranged between two adjacent heat exchanger layers 12, 14, 16 each have two adhesive channels 303, 304, 323, 324. One such positioning element 30 is in Fig. Figure 3, however, shows a configuration for more than four tubes 20, wherein the positioning element 32 is identically designed. The positioning element 30 has an adhesive inlet opening 307, which is fluidically connected to the adhesive channel 303 and, via the opening 306 connecting the two adhesive channels 303, 304, to the adhesive channel 304. When adhesive is inserted via the adhesive inlet opening 307, the adhesive flows into both adhesive channels 303, 304.

[0029] The end-side positioning elements 34, 36 are similarly constructed, with only receiving recesses 341, 361 being provided on one side and only one adhesive channel 342, 362 being provided, which is also filled with adhesive via an adhesive introduction opening.

[0030] During the manufacture of the heat exchanger 10, the tubes 20 of the heat exchanger layers 12, 14, 16, which are connected to each other by the thread 22, are inserted into the receiving recesses 301, 302, 321, 322, 341, 361, thereby positioning the heat exchanger layers 12, 14, 16 relative to each other. Adhesive is then filled into the adhesive channels 303, 304, 323, 324, 342, 362 via the respective adhesive inlet openings 307. Because the adhesive channels 303, 304, 323, 324, 342, 362 are adjacent to the tubes 20 of the corresponding heat exchanger layers 12, 14, 16, a material-bonded, fluid-tight connection exists between the positioning elements 30, 32, 34, 36 and the heat exchanger layers 12, 14, 16 after the adhesive has solidified. Alternatively, the adhesive channels 303, 304, 323, 324, 342, 362 could be omitted, with adhesive being applied to the positioning elements 30, 32, 34, 36 at the corresponding locations before the heat exchanger layers 12, 14, 16 are mounted.Another alternative is that the positioning elements 30, 32, 34, 36 are used as such for a material-bonded connection, wherein after the mounting of the heat exchanger layers 12, 14, 16 on the positioning elements 30, 32, 34, 36 the positioning elements 30, 32, 34, 36 are heated until they melt, wherein after solidification the tubes 20 of the heat exchanger layers 12, 14, 16 are materially bonded to the positioning elements 12, 14, 16.

[0031] The positioning elements 30, 32, 34, 36 are, as in Fig.As shown in Figure 1, two positions 30, 32, 34, 36 are provided at points spaced apart from each other in the longitudinal direction of the tubes 20, i.e., at the locations of the threads 22, thereby defining a flow channel 18 through the positioning elements 30, 32, 34, 36. This channel runs transversely to the longitudinal axis of the tubes 20 of the heat exchanger layers 12, 14, 16 and thus carries flow in a direction S2 transverse to the longitudinal axis of the tubes 20. The heat exchanger layers 12, 14, 16 are aligned with each other such that all tubes 20 carry flow in a common direction S1.

[0032] During operation of the heat exchanger 10, the pipes 20 are filled with a first fluid in the flow direction S1, and the flow channel 18 is filled with a second fluid in the flow direction S2. Heat transfer takes place between the two fluids.

Claims

[1] Heat exchanger (10) with at least two heat exchanger layers (12, 14, 16), each of which has several tubes (20) arranged next to each other, wherein the heat exchanger layers (12, 14, 16) are stacked on top of each other and are firmly connected to each other, wherein at least one positioning element (30, 32) is arranged between the heat exchanger layers (12, 14, 16), which has a receiving recess (301, 302, 321, 322) for each tube (20) for positioning the tubes (20) of the heat exchanger layers (12, 14, 16) relative to each other and is fluid-tightly connected to the heat exchanger layers (12, 14, 16), characterized by , that the tubes (20) of a heat exchanger layer (12, 14, 16) are connected by a thread (22) to form a heat exchanger mat, wherein the positioning element (30, 32, 34, 36) and the thread (22) connecting the tubes (20) overlap in the longitudinal direction of the tubes (20). [2] Heat exchanger (10) according to claim 1, characterized by, that between two adjacent heat exchanger layers (12, 14, 16) two positioning elements (30, 32) are arranged, wherein the two positioning elements (30, 32) fluid-tightly define a flow channel (18) oriented transversely to the longitudinal axis of the tubes (20). [3] Heat exchanger (10) according to claim 1 or 2, characterized by , that on a side facing away from the positioning element (30, 32) at least one of the heat exchanger layers (12, 16) an end-side positioning element (34, 36) is arranged, wherein the end-side positioning element (34, 36) has the receiving recesses (341, 361) exclusively on one side. [4] Heat exchanger (10) according to any one of the preceding claims, characterized by , that the positioning element (30, 32, 34, 36) is materially bonded to the heat exchanger layers (12, 14, 16). [5] Heat exchanger (10) according to claim 4, characterized by, that the positioning element (30, 32, 34, 36) has at least one adhesive channel (303, 304, 323, 324, 342, 362) which extends along the adjacent tubes (20) and has an adhesive inlet opening (307). [6] Heat exchanger (10) according to claim 5, characterized by , that the positioning element (30, 32) arranged between two heat exchanger layers (12, 14, 16) has a groove-like adhesive channel (303, 304, 323, 324) on both sides of the positioning element (30, 32) facing one of the heat exchanger layers (12, 14, 16). [7] Heat exchanger (10) according to claim 6, characterized by , that the adhesive inlet opening (307) is connected to one of the adhesive channels (303, 304; 323, 324), wherein an opening (306) for a connection between the two adhesive channels (303, 304; 323, 324) is provided in an intermediate wall (305, 325). [8] Heat exchanger (10) according to any one of claims 4 to 7, characterized by, that the adhesive inlet opening (307) is located at one end of the positioning element (30, 32, 34, 36). [9] Heat exchanger (10) according to claim 4, characterized by , that the positioning element (30, 32, 34, 36) is made at least partially from a material that melts when exposed to temperature and is designed such that when the material solidifies, the heat exchanger layers (12, 14, 16) are bonded to the positioning element (30, 32, 34, 36). [10] Method for manufacturing a heat exchanger (10) according to any one of claims 1 to 9.

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