COOLER

Description

[0001] The invention relates to a cooler having the features in the preamble of claim 1.

[0002] Coolers operating as liquid-to-air heat exchangers are state of the art; see, for example, DE 10 2014 001 703 A1. To achieve the cooling capacities required for their respective applications, air-to-liquid coolers are typically operated as active coolers with cooling fans that generate the airflow necessary for effective heat exchange within the flow chambers. To avoid the setup and energy costs associated with the use of fans, it is known (see DE 10 2011 107 013 A1) to utilize the wind flow around the nacelle or tower to generate the cooling air in coolers designed to dissipate the waste heat generated by wind turbines to the environment.As shown in the aforementioned document, in an effort to achieve a sufficiently high flow velocity in the flow spaces, the respective heat exchanger on the wind turbine is arranged at a point where the airflow is accelerated by the displacement effect resulting from the geometry of the wind turbine.

[0003] This solution is not optimal insofar as the requirement to position the heat exchanger in a specific location restricts the freedom in designing the geometry of the nacelle and / or tower. Furthermore, despite the specific positioning of the cooler, the effectiveness of the heat exchange leaves something to be desired, so an additional fan may be necessary as an active flow enhancer.

[0004] DE 21 63 951 B2 discloses a heat exchanger of this type with a disturbance element arranged inside a tube through which fluid flows. This disturbance element consists of a thin metal strip with protruding tabs arranged in rows and bent from openings. The bent ends of these tabs rest against the inner wall of the tube, each tab being provided with a window. Additionally, transverse recesses are provided in the metal strip between the openings. This is intended to improve the turbulence of the fluid and thereby ensure good heat transfer.However, due to the impedance introduced by the aforementioned disruptive element, pressure losses occur in any case, even if they are described as small, and the residence time of the fluid to be cooled in the heat exchanger is longer, which reduces the throughput of fluid to be cooled and thus worsens the overall energy balance of the heat exchanger.

[0005] WO 03 / 076860 A1 discloses a further cooler in the form of a heat exchanger with the features in the preamble of claim 1, particularly for motor vehicles, comprising flat tubes through which a first fluid can flow internally, which can be supplied with a second fluid externally, which are arranged substantially transversely to the flow direction of the second fluid and parallel to each other and spaced apart from each other, thereby forming flow paths for the second fluid penetrating the heat exchanger, wherein cooling fins are arranged in the flow paths, each extending between adjacent flat tubes, wherein the cooling fins are several corrugated fins arranged one behind the other in the flow direction of the second fluid, which are laterally offset from each other. The flat tubes are provided with flow guide elements for flow guidance and are connected at their ends to manifolds or collector pipes in a fluid-carrying manner.The corrugated fins each form a single layer of a series of meandering fins, which, arranged one behind the other and viewed transversely to the flow direction of the flat tubes, are offset from each other and have gill-like slots in the fin walls for improved heat transfer of the second fluid, which also contributes to increasing the stability of the heat exchanger.

[0006] Further coolers are derived from DE 20 2011 000 831 U1, US 2012 / 0024510 A1, US 2013 / 0068438 A1, US 2009 / 0020260 A1, US 2014 / 0318753 A1, JP 2010-025462 A and WO 2018 / 100738 A1.

[0007] Based on this state of the art, the invention aims to provide a cooler of the aforementioned type that has a high efficiency, is inherently stable and cost-effective to implement.

[0008] According to the invention, this problem is solved by a cooler which has all the features of claim 1.

[0009] According to the characterizing feature of claim 1, it is provided that the fin rows and the channels extend between two media-carrying main beams, which form the fluid connections with the channels and span a rectangular end face as a cooling surface, that the individual cooling elements are formed in a stacked construction with the channels running parallel to each other, and that each individual cooling element has a composite with two layers of the meandering fins, that the two layers of a cooling element are separated by a partition wall, which each runs in a horizontal plane, and that the channel walls of each channel have a material thickness equal to the wall thickness of a respective fin.

[0010] Because each flow space is free of obstacles and allows laminar flow of the liquid medium through the associated channel in one flow direction, a high throughput of the liquid medium to be cooled is achieved, resulting in energy-efficient operation with high cooling capacity.

[0011] Furthermore, the height of each fin, viewed transversely to the flow direction of the liquid medium, is at least the same as the free flow cross-section of the flow space of the adjacent channel, viewed parallel to the extent of the respective fin, and the fact that in each position a plurality of fin rows of several fins are arranged one behind the other, each offset from the other in the flow direction of the channel, results in a very high airflow compared to single-layer systems due to the stacked layers of the respective cooling element arranged directly above one another, resulting in a high efficiency, so that the cooler according to the invention can be used as a passive heat exchanger utilizing the surrounding airflow with particular advantage in wind turbines, for example according to DE 10 2012 017 462 A1, according to the feature embodiment of claim 13.Without weakening the walls through additional cooling elements, such as gill-like slots, this achieves undisturbed flow guidance with high heat exchange, which can also be implemented in a particularly inherently stable and cost-effective manner.

[0012] The fins of successive floors of the stacked flow chambers, exposed to airflow, are each associated with a specific

[0013] The cooling media channel is in thermal contact. This enables significantly increased heat dissipation from the liquid medium being cooled, so that the cooler according to the invention is characterized by high cooling capacity even at limited flow velocities of the cooling air and can therefore be used with particular advantage and in freely selectable orientations on wind turbines. Fins with a correspondingly large fin height enable a high throughput of cooling air with a correspondingly high heat transfer between the fins of the cooler and the cooling air.

[0014] In a preferred embodiment, it is provided that at least a part of the fins of each layer extend one another in a rib-like manner, forming a wave shape between two opposing deflection points in the manner of connecting ribs, and that in a common plane adjoining the adjacently arranged channels of a cooling element, deflection points of two adjacent layers are aligned congruently towards each other.

[0015] Identical fin components, viewed from the outside in a vertical plane when the cooler is in place, simplify manufacturing, as the same sheet metal shape can always be used for the entire cooler. Sheet metal, preferably made of highly thermally conductive aluminum, can be used as the material. In an advantageous embodiment of the cooler according to the invention, a partition wall runs parallel to the flow direction of the liquid medium in the channels within each plane. This partition wall, which is arranged horizontally during operation of the cooler, increases the stability of the fin positions within the overall assembly and simultaneously enhances heat transfer.

[0016] Advantageously, each partition wall has the same material thickness as the fins that form the wave shape. Using uniform sheet metal thicknesses simplifies manufacturing and reduces costs.

[0017] Advantageously, the fin height of a single, fin-like element is preferably three to six times, and particularly preferably five times, the height of the flow space for the channel carrying the liquid to be cooled. A multiple of this fin height also means a multiple of the air-cooled surface area of ​​the fins relative to the volume of the medium to be cooled in the respective channel. This results in a high throughput of cooling air and a high heat transfer per individual cooling element, from which the cooler is assembled in a stacked configuration. In this respect, an optimum ratio of the medium to be cooled to the cooling medium (air) is achieved.

[0018] Furthermore, the offset is advantageously chosen such that an additional row of fins, arranged between two parallel, mutually unoffset rows of fins, is offset by a predetermined axial distance, parallel to the respective channel, in the direction of flow, relative to the adjacent fins of the two neighboring rows of fins. This offset creates a kind of air divider for the cooling air, resulting in improved, more uniform flow and thus particularly effective heat transfer. The fin offset is also visible in a front view of the cooler, where the offset row projects forward or is set back from the adjacent rows of fins by the aforementioned axial distance, as seen in the direction of fluid flow.

[0019] Advantageously, the arrangement can be such that the offset is between 3 mm and 8 mm, preferably between 4 mm and 6 mm, and particularly preferably between 5 mm and 5.9 mm. Higher offset values ​​are also preferred for fins that have a greater height or length between the adjacent channels.

[0020] In advantageous embodiments, the height of a single fin, viewed transversely to the flow direction of a channel, is between 5 mm and 15 mm, preferably 12 mm, wherein the total depth of the cooler with several rows of fins arranged one behind the other in a horizontal plane is between 60 mm and 90 mm, preferably between 63 mm and 82 mm.

[0021] In particularly preferred embodiments, the thickness or wall thickness of the fins formed from sheet metal is 0.15 mm to 0.4 mm, preferably 0.2 mm, and the thickness of a sheet metal plate serving as a partition between the fin rows is 0.2 mm to 0.8 mm, preferably 0.4 mm. Advantageously, aluminum is used as the sheet metal material for both the fins and the respective channel.

[0022] In particularly advantageous embodiments, the meandering shape of the respective fin rows features fins running parallel to one another, and two adjacent fins of the fin rows are integrally connected to each other via the deflection points or connecting webs, which run parallel to the channels and their boundary walls in the direction of flow. Due to the parallel orientation of the connecting webs at the deflection points, they are in full contact with the boundary walls of the channels, thus forming extensive contact surfaces for heat conduction from the fins to the respective channel. Thermal stresses occurring during operation due to thermally induced expansion are compensated for via these deflection points of the meandering fins.

[0023] In a preferred embodiment of the cooler, 20 to 48, preferably 25 to 63, and particularly preferably 54 channels form the effective cooling surface. The large number of channels enables a favorable ratio of channel surface area to the volume of the medium to be cooled and particularly effective cooling, especially in conjunction with the other geometric design of the cooler.

[0024] A further object of the invention according to claim 13 is a wind turbine in which at least one cooler according to one of claims 1 to 12 is spatially assigned to a nacelle of the turbine, for the purpose of free flow through the flow chambers without fan drive, solely by means of the blade airflow and / or other purely wind-driven ambient air. The cooler according to the invention enables a significantly increased heat dissipation from the liquid medium to be cooled, so that it is characterized by high cooling capacity, even at limited flow velocities of the cooling air, and can therefore be used with particular advantage and in a freely selectable position on the nacelle of wind turbines, facing the environment.

[0025] The invention is explained in detail below with reference to an embodiment illustrated in the drawing. The drawing shows: Fig. 1 is a highly schematically simplified and abbreviated perspective oblique view of the end region of a wind turbine adjacent to the nacelle, which is equipped with two coolers according to the invention; Fig. 2 is a perspective oblique view of an embodiment of the cooler according to the invention; Figs. 3 and 4 are front and top views, respectively, of the embodiment of the cooler; Fig. 5 is a representation of the cooler drawn at approximately two times the size of a practical embodiment. Fig. 3The partial area of ​​the embodiment designated V; Fig. 6 is an end view of a section of two successive rows of fins in the direction of airflow; Figs. 7 and 8 are oblique perspective views and top views, respectively, of three rows of fins successive in the direction of airflow; and Fig. 9 is a perspective view of a part of a channel for the medium to be cooled that is not connected to a main spar, in a frontal end view, with the wall thicknesses shown larger for better illustration.

[0026] The Fig. 1Figure 1 shows a highly simplified representation of a wind turbine 2, specifically the nacelle 4, which is rotatably mounted on a tower 6 that is only indicated. Of a rotor located on the front 8 of the nacelle 4, only a hub 10 with the blade roots 12 of rotor blades (which are otherwise not shown) is visible. On the upper surface 14 of the nacelle 4, two coolers 18 are arranged side by side according to the embodiment of the invention, such that their end faces 16 are exposed to the wind flow running along the nacelle surface 14. Further details of the coolers 18 are shown in the figures. Figs. 2 to 9 removable.

[0027] As the Fig. 2 and 3As shown, the front face 16 of the cooler 18, exposed to the wind flow, has a square outline. On both sides of the front face 16, main beams 20, forming a supporting structure, are attached. Each beam has the form of a rib-like hollow box with an arbitrarily shaped cross-section (square in the illustrated embodiment) and each forms a collection chamber for the liquid medium to be cooled. This medium can be a water-glycol mixture heated by waste heat generated during the operation of the wind turbine, which is to be dissipated into the ambient air. Connections 22 are arranged on the beams 20 for the inlet and outlet of the medium, forming a passage to the interior of the respective collection chamber. While in Figs. 2 to 4The connections shown at the upper ends of the spars 20 indicate that when the coolers 18 are attached to the top 14 of the gondola 4, the connections 22 are expediently provided on the underside facing the top 14 of the gondola.

[0028] In the embodiment shown in the drawing, the side length of the square outline, and thus the depth of the cooler measured perpendicular to the plane of the end face 16, is 63 mm. The drawing plane of Fig. 3 The measured height and spacing of the beams 20 are dimensioned such that the end faces 16 form a rectangular end face 16 exposed to the ambient wind, serving as a cooling surface. Boundary walls 24 run between the beams 20, which are Fig. 2 and 3 are only partially numbered and are formed from thin, flat aluminum plates whose width corresponds to the side length of the square outline of the spars 20, see. Fig. 4The boundary walls 24 are, see. Fig. 5 and 9The walls 24 are grouped in pairs, with the walls running parallel to each other at equal intervals and forming a channel 25 between them, formed by a front wall 23 and a rear wall 23', for the medium to be cooled, particularly in the form of a liquid. The pairs of boundary walls 24, running parallel to each other at equal intervals, each define a complex of two flow chambers 26 and 28 separated by a further plate serving as a partition (27). These chambers are open to ambient air flow from the end face 16, which forms the cooling surface. The channels 25 formed between the boundary walls 24 are connected at their ends to the collection chamber inside the beams 20 and are filled with the liquid medium to be cooled during operation. In the present example, the width of the channels 25, measured transversely to the longitudinal direction of the channel, is 3 mm.

[0029] The cooler 18 shown in the figures is formed from individual cooling elements 1 in a stacked construction with the channels 25 running parallel to each other. Each individual cooling element 1 has a composite with two layers 3, 5 of the meandering fins 34, wherein the two layers 3, 5 of a cooling element 1 are separated by the partition 27, which runs in a horizontal plane E.

[0030] How especially the Fig. 9 As shown, the respective channel 25, with a rectangular, in particular square, cross-section, is bounded on the top and bottom by walls 24, as well as by a front wall 23 and a rear wall 23'. The channel 25 thus forms a kind of flow space 29, which, if kept free of obstructions, allows laminar flow of the liquid medium to be cooled through the channel 25 in one direction.

[0031] The vertical height H1 of each fin 34, viewed perpendicular to the flow direction of the liquid medium, has at least the same height H2 as the free flow cross-section of the flow space 29 of the adjacent channel 25, viewed parallel to the extent of the respective fin 34 in its vertical orientation. In each position 3, 5, there is again a plurality of fin rows 36 of several fins 34, which are arranged one behind the other in a horizontal direction (see figure). Figs. 7 and 8 ), and each seen in the direction of flow through channel 25, an offset P (see. Fig. 6 ) to each other. Viewed horizontally towards the front face of the cooler 18, this axial offset P of the fin rows 36 arranged one behind the other can be seen.

[0032] How the Figs. 5 to 9As can be seen, fins 34 are located in the flow chambers 26 and 28 for the transfer of heat from the liquid medium flowing through the channels 25 to the air flowing through the flow chambers 26 and 28, the surfaces of which are exposed to the flowing cooling air. As is most clearly seen, Figs. 7 and 8As shown in the figures, the fins 34, only partially numbered, are arranged in the fin rows 36, with the fin rows 36 extending in a direction parallel to the plane of the front face 16 and arranged one behind the other in the direction of flow. The identically shaped fins 34 are each formed by sheet metal parts made of aluminum sheet with a rectangular outline, the sheet thickness of which is 0.2 mm in the present embodiment. The fins 34 run in a direction parallel to the direction of airflow and perpendicular to the longitudinal direction of the channels 25 and have a height H1 that corresponds to the height of the associated flow chamber 26 or 28. In the present example, the height of the flow chambers 26 and 28, and accordingly the height H1 of the fins 34, is 10.3 mm.At the ends adjacent to the boundary walls 24, the fins 34 are connected by connecting webs (not all of which are numbered in the figures) that extend integrally through the sheet metal material and form deflection points 38. These connecting webs lie flush against the facing boundary wall 24 and are fixed thereto by gluing or welding. Due to the flush contact of the deflection points 38, each fin 34 is in good thermally conductive contact with a channel 25. This also applies to the connection of the fins 34 to the plate spanning a partition wall 27, which in each case runs in a horizontal direction.

[0033] As the Figs. 7 and 8As shown, the rows 36 of fins 34 are arranged one behind the other without gaps in the direction of airflow with the flow spaces 26, with successive rows of fins 36 being alternately shifted by half the width of the connecting webs or deflection points 38 to one side and the other in the longitudinal direction of the channels 25 and thus axially, viewed in the direction of flow through them. As shown in Fig. 8As indicated by the dashed line 40, zigzag flow paths are formed for the airflow through the flow chambers 26 by means of the flow division. The width of the fins 34, measured in the direction of flow, and their depth, in this example, correspond to the height H1 of the fins 34, whereby the number of fin rows 36, measured in the direction of flow, is selected such that the depth of the present embodiment of the cooler is 63 mm. The width of the connecting webs 38, measured in the longitudinal direction of the channels 29, is selected such that the Fig. 6 The offset of the fins 34, designated by P, is 5 mm in the present embodiment.

[0034] The arrangement of the fin rows 36 provided in the invention and their geometric design with contact surfaces formed via the connecting webs 38 as deflection points on the boundary walls 24 enables particularly effective heat coupling for heat transfer from the heated medium in the channels 25 to the fins 34, which are exposed to airflow over large surface areas. Furthermore, because the fin rows 36 of each flow chamber are in heat exchange with both the air-conducting channels 26 and the channels 28, the coolers according to the invention provide a cooling capacity that allows the coolers 18 to be used for dissipating the waste heat generated during operation without the need for auxiliary, motor-driven fans, regardless of their mounting position on the nacelle 4 of a wind turbine. This has no equivalent in the prior art.

Claims

1. Cooler, with individual cooling elements (1) in a stacked construction with channels (25) running in parallel with one another, each of which delimits a flow chamber (29) for the liquid medium to be cooled to flow through, between which channels at least two layers (3, 5) of individual fin rows (36) of meandering fins (34) extend, which, with one another, in each case delimit a further flow chamber (26, 28) for air to flow through, wherein the respective one flow chamber (29) permits the liquid medium to flow in a laminar manner through the assignable channel (25) in one throughflow direction without any obstacles, in that the height (H1) of each fin (34), viewed across the throughflow direction of the liquid medium, is at least the same height (H2) as the free throughflow cross-section of the flow chamber (29) of the adjacently arranged channel (25), viewed parallel to the extension of the respective fin (34), and in each layer (3, 5) a plurality of fin rows (36) of a plurality of fins (34) are arranged one behind the other, each having an offset (P) to one another when viewed in the throughflow direction of the channel (25), wherein the flow chamber (29) of each channel (25) has a free opening cross-section, which is delimited by exclusively rectangular, peripheral channel walls (23, 23', 24), wherein the fin rows (36) and the channels (25) extend between two media-conveying main spars (20), which form the fluid connections with the channels (25) and span a rectangular end face (16) as a cooler surface, wherein the individual cooling elements (1) are formed in a stacked construction with the channels (25) running in parallel with one another, characterised in that each individual cooling element (1) comprises a composite with two layers (3, 5) of the meandering fins (34), that the two layers (3, 5) of a cooling element (1) are separated by a separating wall (27), which in each case runs in a horizontal plane (E), and in that the channel walls (23, 23', 24) of each channel (25) have a material thickness in the wall thickness of each fin (34).

2. Cooler according to claim 1, wherein at least some of the fins (34) of each layer (3, 5), abutting one another, extend in a web-like manner in each case, forming a wave form between two opposite deflection points (38) and in that, in a common plane (E) abutting the adjacently arranged channels (25) of a cooling element (1), deflection points (38) of two adjacent layers (3, 5) lying on said plane face one another congruently.

3. Cooler according to claim 2, wherein, in the respective plane (E), the separating wall (27) runs in parallel with the flow direction of the liquid medium in the channels (25).

4. Cooler according to claim 3, wherein the respective separating wall (27) has the same material thickness as the fins (34) forming the wave form.

5. Cooler according to any of the preceding claims, wherein the height (H1) of an individual, web-like fin (34) is preferably three to six times, more preferably five times, the height (H2) of the flow chamber (29) for a channel (25).

6. Cooler according to any of the preceding claims, wherein the offset (P) is selected such that a further fin row (36), with its respective fin (34), arranged between two fin rows (36) running parallel with one another without any offset, runs, offset by a pre-definable axial distance, in parallel with the respective channel (25), viewed in the flow direction thereof, with respect to the adjacent fins (34) of the two abutting fin rows (36).

7. Cooler according to any of the preceding claims, wherein the offset (P) is between 3 mm and 8 mm, preferably between 4 mm to 6 mm, more preferably between 5 mm and 5.9 mm.

8. Cooler according to any of the preceding claims, wherein the height (H1) of an individual fin (34), viewed across the throughflow direction of a channel (25), is between 5 mm and 15 mm, preferably 12 mm, and in that the overall depth of each cooling element (1) with a plurality of fin rows (36) arranged one behind the other is between 60 mm and 90 mm, preferably 63 mm and 82 mm, deep.

9. Cooler according to any of the preceding claims, wherein the wall thickness of the fins (34) formed from sheet material is 0.15 mm to 0.4 mm, preferably 0,2 mm, and the wall thickness of the plate consisting of sheet material as a separating wall (27) between the fin rows (36) is 0.2 m to 0.8 mm, preferably 0.4 mm.

10. Cooler according to any of the preceding claims, wherein the meandering form of the respective fin row (36) comprises web-like fins (34) running in parallel with one another and in that two adjacent fins (34) of the fin rows (36) are in each case integrally connected to one another via the deflection points (38) in the form of connecting webs, which run in parallel with the channels (25) with their delimiting walls (24), in the throughflow direction thereof.

11. Cooler according to any of the preceding claims, wherein 20 to 48, preferably 25 to 63, more preferably 54, channels (25) form the effective cooler surface.

12. Wind turbine, comprising at least one cooler according to any of the preceding claims and a spatially assigned nacelle (4) of the turbine, for the purpose of generating a fan-free throughflow through the flow chambers (26, 28) by means of the blade air flow and / or the wind-driven ambient air.